IPCS INCHEM Home


    INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY


    ENVIRONMENTAL HEALTH CRITERIA 162





    BROMINATED DIPHENYL ETHERS





    This report contains the collective views of an international group of
    experts and does not necessarily represent the decisions or the stated
    policy of the United Nations Environment Programme, the International
    Labour Organisation, or the World Health Organization.

    First draft prepared by Dr G.J. van Esch, Bilthoven, Netherlands

    Published under the joint sponsorship of
    the United Nations Environment Programme,
    the International Labour Organisation,
    and the World Health Organization

    World Health Organization
    Geneva, 1994

        The International Programme on Chemical Safety (IPCS) is a joint
    venture of the United Nations Environment Programme, the International
    Labour Organisation, and the World Health Organization. The main
    objective of the IPCS is to carry out and disseminate evaluations of
    the effects of chemicals on human health and the quality of the
    environment. Supporting activities include the development of
    epidemiological, experimental laboratory, and risk-assessment methods
    that could produce internationally comparable results, and the
    development of manpower in the field of toxicology. Other activities
    carried out by the IPCS include the development of know-how for coping
    with chemical accidents, coordination of laboratory testing and
    epidemiological studies, and promotion of research on the mechanisms
    of the biological action of chemicals.

    WHO Library Cataloguing in Publication Data

    Brominated diphenylethers.

    (Environmental health criteria; 162)

    1.Phenyl ethers -- adverse effects      2.Environmental exposure
    3.Occupational exposure                 I.Series

    ISBN 92 4 157162 4         (NLM Classification: QD 341.E7)
    ISSN 0250-863X

        The World Health Organization welcomes requests for permission to
    reproduce or translate its publications, in part or in full.
    Applications and enquiries should be addressed to the Office of
    Publications, World Health Organization, Geneva, Switzerland, which
    will be glad to provide the latest information on any changes made to
    the text, plans for new editions, and reprints and translations
    already available.

    (c) World Health Organization 1994

        Publications of the World Health Organization enjoy copyright
    protection in accordance with the provisions of Protocol 2 of the
    Universal Copyright Convention. All rights reserved.

        The designations employed and the presentation of the material in
    this publication do not imply the expression of any opinion whatsoever
    on the part of the Secretariat of the World Health Organization
    concerning the legal status of any country, territory, city or area or
    of its authorities, or concerning the delimitation of its frontiers or
    boundaries.

        The mention of specific companies or of certain manufacturers'
    products does not imply that they are endorsed or recommended by the
    World Health Organization in preference to others of a similar nature
    that are not mentioned. Errors and omissions excepted, the names of
    proprietary products are distinguished by initial capital letters.

    CONTENTS

    GLOSSARY

    BROMINATED DIPHENYL ETHERS -- GENERAL INTRODUCTION

    1. GENERAL REMARKS

    2. GENERAL INFORMATION ON BROMINATED DIPHENYL ETHERS
         2.1. Analytical methods
         2.2. Production levels and processes
         2.3. Resins, polymers and substrates in which PBDE are used

    3. FORMATION OF BROMINATED DIBENZOFURANS DIPHENYL ETHERS
         3.1. General
         3.2. Additional data on pyrolysis of non-specified PBDE and/or
               polymers containing non-specified PBDE

    4. WORKPLACE EXPOSURE STUDIES
         4.1. Exposure to PBDE
         4.2. Exposure to PBDF/PBDD

    5. EXPOSURE OF THE GENERAL POPULATION
         5.1. General population
         5.2. Possible exposure to PBDE and PBDF/PBDD
               5.2.1. Television sets
               5.2.2. Fire tests and fire accidents

    6. ENVIRONMENTAL POLLUTION BY PBDE
         6.1. Ultimate fate following use
         6.2. Air
         6.3. Soil
         6.4. Water
         6.5. Sediments and sewage sludge
         6.6. Aquatic vertebrates
         6.7. Aquatic mammals
         6.8. Terrestrial vertebrates
               6.8.1. Birds
               6.8.2. Humans

    DECABROMODIPHENYL ETHER

    1. SUMMARY, EVALUATION, CONCLUSIONS, AND RECOMMENDATIONS
         1.1. Summary and evaluation
               1.1.1. Identity, physical and chemical properties
               1.1.2. Production and uses
               1.1.3. Environmental transport, distribution, and
                       transformation
               1.1.4. Environmental levels and human exposure
               1.1.5. Kinetics and metabolism in labortory animals and
                       humans
               1.1.6. Effects on laboratory mammals and  in vitro test
                       systems
               1.1.7. Effects on humans
               1.1.8. Effects on other organisms in the laboratory and
                       field
         1.2. Conclusions
               1.2.1. DeBDE
               1.2.2. Breakdown products
         1.3. Recommendations
               1.3.1. General
               1.3.2. Further studies

    2. IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, ANALYTICAL METHODS
         2.1. Identity
               2.1.1. Pure substance
               2.1.2. Technical product

         2.2. Physical and chemical properties
         2.3. Analytical methods

    3. SOURCES OF HUMAN AND ENVIRONMENTALEXPOSURE
         3.1. Natural occurrence
         3.2. Anthropogenic sources
               3.2.1. Production levels and processes
               3.2.2. Uses

    4. ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION
         4.1. Transport and distribution between media
               4.1.1. Extraction from polymers
         4.2. Biotransformation
         4.3. Abiotic degradation
               4.3.1. Photodegradation
               4.3.2. Pyrolysis
               4.3.3. Combustion of DeBDE and polymers containing DeBDE
                       4.3.3.1   Pyrolysis studies
                       4.3.3.2   Workplace exposure studies

         4.4. Ultimate fate following use
               4.4.1. General
               4.4.2. Exposure of the general population
         4.5. Fire accident
         4.6. Simulated fire conditions
         4.7. Bioaccumulation

    5. ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE
         5.1. Environmental levels
               5.1.1. Air
               5.1.2. Water
               5.1.3. Aquatic sediments
               5.1.4. Aquatic and terrestrial organisms
         5.2. Exposure of humans
               5.2.1. Occurrence of DeBDE in human tissues
               5.2.2. Occupational exposure

    6. KINETICS AND METABOLISM IN LABORATORY ANIMALS AND HUMANS
         6.1. Absorption and elimination
         6.2. Distribution
         6.3. Retention and turnover

    7. EFFECTS ON LABORATORY MAMMALS AND  IN VITRO TEST SYSTEMS
         7.1. Single exposure
               7.1.1. Oral: Rat
               7.1.2. Dermal: Rabbit
               7.1.3. Inhalation: Rat
         7.2. Short-term exposure
               7.2.1. Oral
                       7.2.1.1   Mouse
                       7.2.1.2   Rat
               7.2.2. Inhalation
                       7.2.2.1   Rat
         7.3. Long-term exposure
               7.3.1. Oral
                       7.3.1.1   Mouse
                       7.3.1.2   Rat
         7.4. Skin and eye irritation; sensitization
               7.4.1. Skin irritation
               7.4.2. Eye irritation
               7.4.3. Sensitization
               7.4.4. Chloracnegenic activity
         7.5. Reproductive toxicity, embryotoxicity, and teratogenicity
               7.5.1. Reproductive toxicity
               7.5.2. Teratogenicity
         7.6. Mutagenicity and related end-points
               7.6.1. Mutation
               7.6.2. Chromosomal effects
         7.7. Carcinogenicity
               7.7.1. Oral
                       7.7.1.1   Mouse
                       7.7.1.2   Rat

         7.8. Other special studies
               7.8.1. Liver
               7.8.2. Miscellaneous
               7.8.3. Toxicity of soot, char, and other waste products
                       from combustion of DeBDE-containing polymers
                       7.8.3.1   Acute oral toxicity
                       7.8.3.2   Skin irritation and comedogenicity
                       7.8.3.3   Eye irritation

    8. EFFECTS ON HUMANS
         8.1. General population exposure
         8.2. Occupational exposure
               8.2.1. Skin sensitization
               8.2.2. Neurotoxicity
               8.2.3. Epidemiological studies

    9. EFFECTS ON OTHER ORGANISMS IN THE LABORATORY AND FIELD

    10. PREVIOUS EVALUATIONS BY INTERNATIONAL BODIES

    NONABROMODIPHENYL ETHER

    1. SUMMARY, EVALUATION, CONCLUSIONS AND RECOMMENDATIONS
         1.1. Summary and evaluation
         1.2. Recommendations

    2. IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, ANALYTICAL METHODS
         2.1. Identity
         2.2. Physical and chemical properties
         2.3. Analytical methods

    3. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE
         3.1. Natural occurrence
         3.2. Anthropogenic sources
               3.2.1. Production levels and processes
               3.2.2. Uses

    OCTABROMODIPHENYL ETHER

    1. SUMMARY, EVALUATION, CONCLUSIONS AND RECOMMENDATIONS
         1.1. Summary and evaluation
               1.1.1. Identity, physical and chemical properties
               1.1.2. Production and uses
               1.1.3. Environmental transport, distribution, and
                       transformation
               1.1.4. Environmental levels and human exposure
               1.1.5. Kinetics and metabolism in laboratory animals and
                       humans
               1.1.6. Effects on laboratory mammals and  in vitro test
                       systems
               1.1.7. Effects on humans
               1.1.8. Effects on other organisms in the laboratory and
                       field
         1.2. Conclusions
               1.2.1. OBDE
               1.2.2. Breakdown products

        1.3. Recommendations
               1.3.1. General
               1.3.2. Further studies

    2. IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, ANALYTICAL METHODS
         2.1. Identity
               2.1.1. Technical product
         2.3. Physical and chemical properties
         2.3. Analytical methods

    3. SOURCES OF HUMAN AND ENVIRONMENTALEXPOSURE
         3.1. Natural occurrence
         3.2. Anthropogenic sources
               3.2.1. Production levels and processes
               3.2.2. Uses

    4. ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION
         4.1. Biotransformation
         4.2. Abiotic degradation
               4.2.1. Pyrolysis of octabromodiphenyl ether
               4.2.2. Pyrolysis studies with polymers containing
                       octabromodiphenyl ether
               4.2.3. Behaviour of octabromodiphenyl ether during
                       processing
         4.3. Bioaccumulation
         4.4. Ultimate fate following use

    5. ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE
         5.1. Environmental levels
               5.1.1. Water
               5.1.2. Aquatic sediments
               5.1.3. Aquatic and terrestrial organisms
         5.2. Exposure of the general population
         5.3. Occupational exposure during manufacture, formulation or
               use

    6. EFFECTS ON LABORATORY MAMMALS AND  IN VITRO TEST SYSTEMS
         6.1. Single exposure
               6.1.1. Oral: Rat
               6.1.2. Dermal: Rabbit
               6.1.3. Inhalation: Rat
         6.2. Short-term exposure
               6.2.1. Oral: Rat
               6.2.2. Inhalation: Rat
         6.3. Long-term exposure
         6.4. Skin and eye irritation; sensitization
               6.4.1. Skin irritation
               6.4.2. Eye irritation

         6.5. Teratogenicity, reproductive toxicity,
               and embryotoxicity
               6.5.1. Teratogenicity
                       6.5.1.1   Oral: Rat
                       6.5.1.2   Oral: Rabbit
         6.6. Mutagenicity and related end-points
               6.6.1. DNA damage
               6.6.2. Mutation
               6.6.3. Chromosomal effects
         6.7. Carcinogenicity
         6.8. Other special studies
               6.8.1. Liver
         6.9. Appraisal

    HEPTABROMODIPHENYL ETHER

    1. SUMMARY, EVALUATION, CONCLUSIONS AND RECOMMENDATIONS

    2. IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, AND ANALYTICAL
         METHODS
         2.1. Identity
         2.2. Physical and chemical properties
         2.3. Analytical methods

    3. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE
         3.1. Natural occurrence
         3.2. Anthropogenic sources
               3.2.1. Production levels and processes

    4. ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION

    5. ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE

    6. EFFECTS ON LABORATORY MAMMALS AND  IN VITRO TEST SYSTEMS
         6.1. Single exposure
         6.2. Skin and eye irritation; sensitization

    HEXABROMODIPHENYL ETHER

    1. SUMMARY, EVALUATION, CONCLUSIONS AND RECOMMENDATIONS

    2. IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, ANALYTICAL METHODS
         2.1. Identity
               2.1.1. Technical product
         2.2. Physical and chemical properties
         2.3. Analytical methods

    3. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE
         3.1. Natural occurrence
         3.2. Anthropogenic sources
         3.3. Uses

    4. ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION

    5. ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE
         5.1. Levels in the environment
               5.1.1. Water
               5.1.2. Aquatic sediments
               5.1.3. Aquatic and terrestrial organisms
         5.2. General population exposure

    6. KINETICS AND METABOLISM IN LABORATORY ANIMALS AND HUMANS

    PENTABROMODIPHENYL ETHER

    1. SUMMARY, EVALUATION, CONCLUSIONS AND RECOMMENDATIONS
         1.1. Summary and evaluation
               1.1.1. Identity, physical and chemical properties
               1.1.2. Production and uses
               1.1.3. Environmental transport, distribution and
                       transformation
               1.1.4. Environmental levels and human exposure
               1.1.5. Kinetics and metabolism in laboratory animals and
                       humans
               1.1.6. Effects on laboratory mammals and  in vitro test
                       systems
               1.1.7. Effects on humans
               1.1.8. Effects on other organisms in the laboratory and
                       field
         1.2. Conclusions
               1.2.1. PeBDE
               1.2.2. Breakdown products
         1.3. Recommendations
               1.3.1. General
               1.3.2. Further studies

    2. IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, ANALYTICAL METHODS
         2.1. Identity
               2.1.1. Technical product
         2.2. Physical and chemical properties
         2.3. Analytical methods

    3. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE
         3.1. Natural occurrence
         3.2. Anthropogenic sources
               3.2.1. Production levels and processes
               3.2.2. Uses

    4. ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION
         4.1. Pyrolysis
         4.2. Workplace exposure studies
         4.3. Bioaccumulation
         4.4. Ultimate fate following use

    5. ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE
         5.1. Levels in the environment
               5.1.1. Sediment and sewage sludge
               5.1.2. Fish and shellfish
               5.1.3. Aquatic mammals
               5.1.4. Terrestrial mammals
               5.1.5. Birds
         5.2. General population

    6. KINETICS AND METABOLISM IN LABORATORY ANIMALS AND HUMANS

    7. EFFECTS ON LABORATORY MAMMALS AND  IN VITRO TEST SYSTEMS
         7.1. Single exposures
               7.1.1. Oral
               7.1.2. Dermal
               7.1.3. Inhalation
         7.2. Short-term exposure
         7.3. Long-term exposure
         7.4. Skin and eye irritation; sensitization
               7.4.1. Skin irritation
               7.4.2. Eye irritation
         7.5. Reproductive toxicity, embryotoxicity and teratogenicity
         7.6. Mutagenicity and related end-points
         7.7. Carcinogenicity
         7.8. Other special studies

    TETRABROMODIPHENYL ETHER

    1. SUMMARY, EVALUATION, CONCLUSIONS AND RECOMMENDATIONS
         1.1. Summary and evaluation
               1.1.1. Identity, physical and chemical properties
               1.1.2. Production and uses
               1.1.3. Environmental transport, distribution, and
                       transformation
               1.1.4. Environmental levels and human exposure
               1.1.5. Effects on laboratory mammals and  in vitro test
                       systems
               1.1.6. Kinetics and metabolism in laboratory animals and
                       humans
               1.1.7. Effects on humans
               1.1.8. Effects on other organisms in the laboratory and
                       field
         1.2. Conclusions
               1.2.1. TeBDE
               1.2.2. Breakdown products
         1.3. Recommendations
               1.3.1. General
               1.3.2. Further studies

    2. IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, ANALYTICAL METHODS
         2.1. Identity
         2.2. Physical and chemical properties
         2.3. Analytical methods

    3. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE
         3.1. Natural occurrence
         3.2. Anthropogenic sources
               3.2.1. Production levels and processes
               3.2.2. Uses

    4. ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION
         4.1. Pyrolysis
         4.2. Ultimate fate following use

    5. ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE
         5.1. Environmental levels
               5.1.1. Soil and sediment
               5.1.2. Fish and shellfish
               5.1.3. Birds
               5.1.4. Aquatic mammals
               5.1.5. Terrestrial mammals
         5.2. General population exposure

    6. KINETICS AND METABOLISM IN LABORATORY ANIMALS AND HUMANS

    TRIBROMODIPHENYL ETHER

    1. SUMMARY, EVALUATION, CONCLUSIONS AND RECOMMENDATIONS
         1.1. Summary and evaluation
         1.2. Recommendations

    2. IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, ANALYTICAL METHODS
         2.1. Identity
         2.2. Physical and chemical properties
         2.3. Analytical methods

    3. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE

    4. ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE
         4.1. Environmental levels
               4.1.1. Birds

    DIBROMODIPHENYL ETHER

    1. SUMMARY, EVALUATION, CONCLUSIONS AND RECOMMENDATIONS
         1.1. Summary and evaluation
         1.2. Recommendations

    2. IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, ANALYTICAL METHODS
         2.1. Identity
         2.2. Physical and chemical properties
         2.3. Analytical methods

    3. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE
         3.1. Natural occurrence
         3.2. Anthropogenic sources
               3.2.1. Production levels and processes

    4. ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION

    5. ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE
         5.1. Environmental levels
               5.1.1. Water
               5.1.2. Soil/sediment
               5.1.3. Birds
         5.2. General population exposure

    6. EFFECTS ON LABORATORY MAMMALS AND  IN VITRO TEST SYSTEMS
         6.1. Single exposure
         6.2. Other special studies
               6.2.1. Liver

    MONOBROMODIPHENYL ETHER

    1. SUMMARY, EVALUATION, CONCLUSIONS AND RECOMMENDATIONS
         1.1. Summary and evaluation
               1.1.1. Physical and chemical properties
               1.1.2. Production and uses
               1.1.3. Environmental transport, distribution, and
                       transformation
               1.1.4. Environmental levels and human exposure
               1.1.5. Kinetics and metabolism in laboratory animals and
                       humans
               1.1.6. Effects on laboratory mammals and  in vitro test
                       systems
               1.1.7. Effects on humans
               1.1.8. Effects on other organisms in the laboratory and
                       field
         1.2. Conclusions and recommendations

    2. IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, ANALYTICAL METHODS
         2.1. Identity
         2.2. Physical and chemical properties
         2.3. Analytical methods

    3. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE
         3.1. Natural occurrence
         3.2. Anthropogenic sources
               3.2.1. Production levels and processes
               3.2.2. Uses

    4. ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION
         4.1. Transport and distribution between media
         4.2. Biotransformation
               4.2.1. Biodegradation

    5. ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE
         5.1. Environmental levels
               5.1.1. Water
               5.1.2. Soil/Sediment
               5.1.3. Aquatic organisms

    6. EFFECTS ON LABORATORY MAMMALS AND  IN VITRO TEST SYSTEMS
         6.1. Reproductive toxicity, embryotoxicity,
               teratogenicity
         6.2. Carcinogenicity

    7. EFFECTS ON OTHER ORGANISMS IN THE LABORATORY AND FIELD

    REFERENCES

    RESUME ET EVALUATION, CONCLUSIONS ET RECOMMANDATIONS

    RESUMEN, EVALUACION, CONCLUSIONES Y RECOMENDACIONES

    

    GLOSSARY

    PBDE        polybrominated diphenyl ethers
    MBDE        monobromodiphenyl ethers
    DiBDE       dibromodiphenyl ethers
    TrBDE       tribromodiphenyl ethers
    TeBDE       tetrabromodiphenyl ethers
    PeBDE       pentabromodiphenyl ethers
    HxBDE       hexabromodiphenyl ethers
    HpBDE       heptabromodiphenyl ethers
    OBDE        octabromodiphenyl ethers
    NBDE        nonabromodiphenyl ethers
    DeBDE       decabromodiphenyl ethers

    PBDF        polybrominated dibenzofurans
    TeBDF       tetrabromodibenzofurans
    PeBDF       pentabromodibenzofurans
    HxBDF       hexabromodibenzofurans
    HpBDF       heptabromodibenzofurans

    PBDD        polybrominated dibenzodioxins
    TeBDD       tetrabromodibenzodioxins
    PeBDD       pentabromodibenzodioxins
    HxBDD       hexabromodibenzodioxins
    HpBDD       heptabromodibenzodioxins

    PBBz        polybrominated benzenes
    PBP         polybrominated phenols
    PBN         polybrominated naphthalenes
    PBB         polybrominated biphenyls
    PCB         polychlorinated biphenyls
    THP         Tetrakis(hydroxymethyl)phosphonium salts

    ABS         acrylonitrile-butadiene-styrene
    BASF        Badische Anilin und Soda Fabrik
    BFRIP       Brominated Flame Retardant Industry Panel
    BOD         biochemical oxygen demand
    CEFIC       Conseil Européen de l'Industrie Chimique (European
                Chemical Industry Council)
    DTA         differential thermal analysis
    EBFRIP      European Brominated Flame Retardant Industry Panel
    EEC         European Economic Community
    ER          epoxy resin
    FY          Fiscal Year
    GC/ECD      gas chromatography/electron capture detector
    GC/MS       gas chromatography/mass spectrometry
    HIPS        high impact polystyrene
    HPLC        high pressure liquid chromatography
    HRGC/MS     high resolution gas chromatography/mass spectrometry

    IG          ignition loss
    NCI         negative chemical ionization
    NHATS       National Human Adipose Tissue Survey
    NIOSH       National Institute of Occupational Safety and Health
    PA          polyamide
    PAN         polyacrylonitrile
    PBT         polybutylene terephthalate
    PE          polyethylene
    PET         polyethylene terephthalate
    PP          polypropylene

    PR          phenolic resin
    PS          polystyrene
    PUR         polyurethane
    PVC         polyvinylchloride
    SIM         selective ion monitoring
    TGA         thermal gravimetric analysis
    UPE         unsaturated (Thermoset) polyesters
    US          EPA United States Environmental Protection Agency
    US          NTP United States National Toxicology Program
    XPE         cross-linked polyethylene

    WHO TASK GROUP ON ENVIRONMENTAL HEALTH CRITERIA FOR BROMINATED
    DIPHENYL ETHERS

     Members

    Dr L.A. Albert, Consultores Ambientales Asociados, S.C., Xalapa,
    Veracruz, Mexico  (Vice-Chairman)

    Dr S. Dobson, Institute of Terrestrial Ecology, Monks Wood
    Experimental Station, Cambridgeshire, United Kingdom

    Professor   B. Jansson, Institute of Applied Environmental Research,
    Stockholm   University, Solna, Sweden

    Dr J. Kielhorn, Fraunhofer Institute for Toxicology and Aerosol
    Research, Hanover, Germany

    Dr M. Luotamo, Finnish Institute of Occupational Health, Helsinki,
    Finland

    Professor Wai-On Phoon, Worksafe Australia, and University of Sydney,
    Sydney, Australia  (Chairman)

    Mr J. Rea, Department of Environment, London, United Kingdom

    Dr S. Sleight, Department of Pathology, Michigan State University,
    East Lansing, USA

     Observers

    Dr M.L. Hardy, Health and Environment, Ethyl Corporation, Baton Rouge,
    USA

    Dr D.L. McAllister, Quality Assurance and Research Services,

    Great Lakes Chemical Corporation, West Lafayette, Indiana, USA

     Secretariat

    Dr K.W. Jager, International Programme on Chemical Safety, World
    Health Organization, Geneva, Switzerland  (Secretary)

    Dr G.J. van Esch, Bilthoven, The Netherlands  (Rapporteur)

    NOTE TO READERS OF THE CRITERIA DOCUMENTS

        Every effort has been made to present information in the criteria
    documents as accurately as possible without unduly delaying their
    publication. In the interest of all users of the environmental health
    criteria documents, readers are kindly requested to communicate any
    errors that may have occurred to the Director of the International
    Programme on Chemical Safety, World Health Organization, Geneva,
    Switzerland, in order that they may be included in corrigenda, which
    will appear in subsequent volumes.

                                     * * *

        A detailed data profile and a legal file can be obtained from the
    International Register of Potentially Toxic Chemicals, Case Postale
    356, 1219 Chatelaine, Geneva, Switzerland (Telephone No. 9799111).

                                     * * *

        This publication was made possible by grant number 5 U01
    ES02617-14 from the National Institute of Environmental Health
    Sciences, National Institutes of Health, USA.

    NOTE: The proprietary information contained in this document cannot
    replace documentation for registration purposes, because the latter
    has to be closely linked to the source, the manufacturing route, and
    the purity/impurities of the substance to be registered. The data
    should be used in accordance with paragraphs 82-84 and recommendations
    paragraph 90 of the Second FAO Government Consultation (1982).

    ENVIRONMENTAL HEALTH CRITERIA FOR BROMINATED DIPHENYL ETHERS

        A WHO Task Group on Environmental Health Criteria for Brominated
    Diphenyl Ethers met at the World Health Organization, Geneva, from
    28 June to 2 July 1993. Dr K.W. Jager, of the IPCS, welcomed the
    participants on behalf of Dr M. Mercier, Director IPCS, and the three
    cooperating organizations (UNEP/ILO/WHO). The Group reviewed and
    revised the draft criteria monograph and made an evaluation of the
    risks for human health and the environment from exposure to brominated
    diphenyl ethers.

        The first draft of the monograph was prepared by Dr G.J. van Esch
    of the Netherlands, who also prepared the second draft, incorporating
    comments received following circulation of the first draft to the IPCS
    contact points for Environmental Health Criteria monographs.

        Dr K.W. Jager of the IPCS Central Unit was responsible for the
    scientific content of the monograph, and Mrs M.O. Head of Oxford,
    England, for the editing.

        The fact that industry made proprietary toxicological information
    available to the IPCS and the Task Group on the products under
    discussion is gratefully acknowledged. This allowed the Task Group to
    make its evaluation on a more complete data base.

        The efforts of all who helped in the preparation and finalization
    of the document are gratefully acknowledged.

    BROMINATED DIPHENYL ETHERS GENERAL INTRODUCTION

    1.  GENERAL REMARKS

        This Environmental Health Criteria monograph on brominated
    diphenyl ethers has been prepared as part of an overview on the impact
    of a number of flame retardants on human health and the environment.
    The group of polybrominated diphenyl ethers (PBDE) has been selected
    as a priority because of the recent interest in these substances. Only
    products based on penta-, octa-, and decabromodiphenyl ethers are of
    commercial interest.

        The general chemical formula of brominated diphenyl ethers is:

    CHEMICAL STRUCTURE 1

        Polybrominated diphenyl ethers (PBDE) have a large number of
    congeners, depending on the number and position of the bromine atoms
    on the two phenyl rings. The total number of possible congeners is
    209, and the numbers of isomers for mono-, di-, tri- up to
    decabromodiphenyl ethers are: 3, 12, 24, 42, 46, 42, 24, 12, 3, and 1,
    respectively.

        The commercial PBDE are produced by the bromination of diphenyl
    oxide under certain conditions, which result in products containing
    mixtures of brominated diphenyl ethers (see the individual PBDE). The
    compositions of commercial DeBDE, OBDE, and PeBDE are given in
    Table 1.

        No, or virtually no, data are available on dibromo-, tribromo-,
    hexabromo-, heptabromo-, and nonabromodiphenyl ether (DiBDE, TrBDE,
    HxBDE, HpBDE, and NBDE, respectively). Flame retardants containing
    predominantly penta-, octa- and decabromodiphenyl ethers are
    commercially produced (with tetrabromodiphenyl ether as a major
    component of "pentabromo-diphenyl ether", which is a mixture).

        The commercial PBDE are rather stable compounds with boiling
    points ranging between 310 and 425 °C and with low vapour pressures,
    e.g., 3.85 up to 13.3 Pa at 20-25 °C; they are lipophilic substances.
    Their solubility in water is very poor, especially that of the higher
    brominated diphenyl ethers, and the  n-octanol/water partition
    coefficients (log Pow) range between 4.28 and 9.9.

        Polybrominated diphenyl ethers have not been reported to occur
    naturally in the environment, but other types of brominated diphenyl
    ethers have been found in marine organisms (Carte & Faulkner, 1981;
    Faulkner, 1990).

        The presence in the environment of some of the brominated diphenyl
    ethers has been documented, the highest concentration being 1 g/kg
    sediment in streams or ponds in the vicinity of a manufacturing
    facility.

        Data on environmental fate, although limited to MBDE, DiBDE, and
    DeBDE, suggest that biodegradation is not an important degradation
    pathway for the PBDE, but that photodegradation may play a significant
    role.


        Table 1.  Composition of commercial brominated diphenyl ethers
                                                                                                            

    Product                                         Composition
                                                                                                            

               PBDEa    TrBDE     TeBDE       PeBDE        HxBDE     HpBDE     OBDE      NBDE      DeBDE
                                                                                                            

    DeBDE                                                                               0.3-3%    97-98%
    OBDE                                                  10-12%    43-44%    31-35%     9-11%     0-1%
    PeBDE               0-1%      24-38%      50-62%       4-8%
    TeBDEb     7.6%      --       41-41.7%    44.4-45%     6-7%
                                                                                                            

    a  Unknown structure.
    b  No longer commercially produced. Analysis of one single sample.

    

        Many reports have appeared in the literature describing the
    behaviour of brominated flame retardants under pyrolytic conditions.
    In general, these reports have indicated that maximum concentrations
    of PBDF and/or PBDD were observed at temperatures of 400-800 °C and
    that the 2,3,7,8-substituted compounds were seen only in very low
    concentrations.

        Processing of the polymers under abusive or extreme conditions
    produced higher levels of PBDF, but the concentrations were
    significantly lower than the values previously reported from
    laboratory pyrolysis studies. 2,3,7,8-Brominated isomers were only
    found at low levels in a sample abusively processed. The
    2,3,7,8-brominated isomers, which are of concern for toxicological and
    regulatory reasons, were not detected under normal processing
    conditions. The results of the laboratory pyrolysis experiments with
    PBDE, showed that PBDF and/or PBDD were formed in various
    concentrations, depending on the type of PBDE, the polymer matrix, the
    specific processing conditions (temperature, presence of oxygen, etc.)
    and equipment used, and the presence of Sb2O3. Behaviour of PBDE is
    strongly dependent upon the polymer matrix and upon the specific
    processing conditions mentioned above, thus laboratory pyrolysis
    experiments can hardly be used as reliable models to predict behaviour
    in commercial moulding operations.

    2.  GENERAL INFORMATION ON BROMONATED DIPHENYL ETHERS

    2.1  Analytical methods

        Several methods to determine residues of PBDE in various media
    (air, sewage sludge, sediment, human adipose tissue, marine organisms,
    fish, and feed) as well as in commercial products have been reported.
    For details, see Table 2.

        In general, sample extraction and clean-up techniques for the
    analysis of PBDE residues in biological samples are similar to those
    developed for PBB (see EHC 152:  Polybrominated biphenyls), though
    the chromatographic conditions have to be modified in view of the long
    retention times of the highly brominated PBDE. Temperature programming
    and the use of capillary columns have been found to be very useful for
    the separation of the different congeners of PBDE. Recovery for the
    different PBDE is generally higher than 80%. Most methods are based on
    extraction with organic solvents, such as hexane/acetone,
    hexane/diphenyl ether, acetone, etc, purification of the extracts by
    gel permeation or adsorption chromatography, and determination mainly
    by gas chromatography, either with electron capture detection (ECD),
    or, coupled with mass spectrometry (MS). A multi-residue method has
    also been developed that includes a multi-step separation enabling the
    determination of several polychlorinated and polybrominated pollutants
    in biological samples (Jansson et al., 1991).


        Table 2.  Analytical methods for PBDE
                                                                                                                                

    Sample                    Extraction and clean-up                       Separation and      Limit of        Reference
                                                                               detection      determination
                                                                                                                                

    Sewage            extract with chloroform; evaporate and dissolve        GC/MS            0.06 mg/kg        Kaart & Kokk
                      residue in ethanol                                                                        (1987)

    Sediment          extract with acetone; clean-up on Florisil             NAA;             < 5 µg/kg         Watanabe et al.
                                                                             GC/EC            < 5 µg/kg         (1987b)

    Fish              extract with acetone-hexane + hexane-ethyl ether;      GC/EC;           limit of          Andersson &
                      treatment with sulfuric acid or clean-up on alumina;   GC/MS            detection         Blomkvist
                      chromatography on silica gel                                            0.1 mg/kg fat     (1981)

    Animal tissues    homogenize; extract with n-hexane-acetone;             GC/MS (NCl)      10 ng/kg          Jansson et al.
    (Multi-residue    treatment with sulfuric acid; gel permeation                                              (1991)
    method)           chromatography; chromatography or silica gel;
                      chromatography or activated charcoal

    Rat liver         extract with tetrahydrofuran                           HPLC                               Rogers & Hill
                                                                                                                (1980)
                                                                                                                                

    Table 2 (continued)
                                                                                                                                

    Sample                    Extraction and clean-up                       Separation and      Limit of        Reference
                                                                               detection      determination
                                                                                                                                

    Fish              extract freeze-dried powdered sample with pet. ether;  GC/MS            < 5 µg/kg fat     Kruger (1988)
                      gel permeation chromatography; clean-up on Florisil;   (NCl/SIM)
                      elute with hexane

    Cow's milk        centrifuge; gel permeation chromatography; clean-up    GC/MS            < 2.5 µg/kg fat   Kruger (1988)
                      on Florisil; elute with hexane                         (NCl/SIM)

    Human milk        extract with potassium oxalate/ethanol/diethyl         GC/MS            < 0.6 µg/kg fat   Kruger (1988)
                      ether/pentane; gel permeation chromatography;          (NCl/SIM)
                      clean-up on Florisil; elute with hexane

    Human adipose     extract with methylene chloride; evaporate; clean-up   HRGC/HRMSa       limit of          Cramer et al.
    tissue            on silica gel followed by clean-up on alumina and on                    detection         (1990a,b)
                      a carbon/silica gel column                                              0.73-120 ng/kg
                                                                                              (different
                                                                                              congeners)

    Commercial PBDE   homogenize and dissolve in tetrachloromethane for      HPLC; GC/MS;        --             deKok et al.
                      HPLC and GC/MS or n-hexane for TLC/UV                  TLC/UV                             (1979)
                                                                                                                                

    a  High resolution gas chromatography/high resolution mass spectrometry.

    

    2.2  Production levels and processes

        According to the information given by the European Brominated
    Flame Retardant Industry Panel (EBFRIP), eight manufacturers are
    currently producing polybrominated diphenyl ethers. They are: Dead Sea
    Bromines/Eurobrome (The Netherlands); Atochem (France); Ethyl
    Corporation (USA); Great Lakes Chemical Corporation (USA); Tosoh
    (Japan); Matsunaga (Japan); Nippo (Japan); Great Lakes Chemical Ltd
    (United Kingdom).

        The annual global consumption of PBDE is 40 000 tonnes (30 000
    tonnes of DeBDE; 6000 tonnes OBDE and 4000 tonnes PeBDE) (Arias,
    1992).

        It has been reported that the use of brominated flame retardants
    in Japan increased from 2500 tonnes in 1975 to 22 100 tonnes in 1987
    (Watanabe & Tatsukawa, 1990).

        The production and import figures for the European Economic
    Community (EEC) are given in Table 3.

    Table 3.  Production and import quantities of PBDE in metric
              tonnes in the EECa
                                                                    

                   1986        1987      1988        1989
                                                                    

    Production     4276        3624      4066        3843
    Import         4310        3492      4955        7103
    Total          8586        7116      9021      10 946
                                                                    

    aFrom:  EBFRIP (1990).

        Data on the usage of PBDE are available for some individual
    European countries. Germany uses 3000-5000 tonnes/year, Sweden
    1400-2000 tonnes/year, and The Netherlands 3300-3700 tonnes/year
    (OECD, 1991; van Zorge, 1992), but Pijnenburg & Everts (1991) and
    Pijnenburg et al. (1992) reported a level of 2500 tonnes PBDE for the
    last country. In the United Kingdom, up to 2000 tonnes per year are
    used (UK DOE, 1993).

        Because of the significant reduction in the fire hazard for the
    public achieved by the use of PBDE in a wide range of applications,
    particularly in the furniture industry, and electrical/computer
    components and housing, the consumption of PBDE has significantly
    increased over the last years (EBFRIP, 1990).

    2.3  Resins, polymers, and substrates in which PBDE are used

        The major uses of the polybrominated diphenyl ethers in descending
    order of importance are: high-impact polystyrene, ABS, flexible
    polyurethane foam, textile coatings (not clothing), wire and cable
    insulation, electrical/electronic connectors and other interior parts.
    These applications account for at least 80-90% of the consumption of
    brominated diphenyl ethers in the USA.

        Brominated diphenyl ethers are used as additive flame retardants.
    Additive flame retardants are incorporated into the plastic matrix
    like other additives, such as plasticizers. The ideal additive is
    inexpensive, colourless, easily blended, compatible, heat and light
    stable, efficient, permanent, and has no deleterious effect on the
    properties of the base polymer. The most important limitations are
    incompatibilities that affect the physical properties of the polymers
    and the tendency for additives to be fugitive. These additive flame
    retardants are much more prone to leaching or escape from the finished
    polymer product than the reactive flame retardants (Hutzinger et al.,
    1976; Hutzinger & Thoma, 1987; Larsen, 1980).

        The uses of penta-, octa-, and decabromodiphenyl ethers in the
    different resins, polymers, and substrates are shown in Table 4. The
    principal applications of these PBDE-containing substances are shown
    in Table 5.

        PBDE are used in the different resins, polymers, and substrates at
    levels ranging from 5 up to 30%. The quantities used for each
    application are not publicly available. In consumer products, resins
    containing PBDE are typically used in interior parts, minimizing the
    potential for exposure of the public. The incorporation of the PBDE
    into the polymer matrix further reduces the possibilities of exposure
    (EBFRIP, 1990).

        Table 4.  Use of penta- (PeBDE), octa- (OBDE), and decabromodiphenyl ethers
              (DeBDE) in resins, polymers, and substratesa
                                                                                   

    Resins/polymers/substrates      DeBDE         OBDE           PeBDE
                                                                                   

    ABS                                            X
    Epoxy-resins                      X
    Phenolic resins                   X                            X
    PAN                               X
    PA                                X            X
    PBT                               X            X
    PE/XPE                            X
    PET                               X
    PP                                X
    PS, HIPS                          X            X
    PVC                               X                            X
    PUR                                                            X
    UPE                               X                            X
    Rubber                            X                            X
    Paints/lacquers                   X                            X
    Textiles                          X                            X
                                                                                   

    aFrom:  EBFRIP (1990); UK Department of Environment (1992).

    Table 5.  The various applications of resins in which PBDE are used are listed belowa
                                                                                             

    Polymer       Principal applications       Examples of final products
                                                                                             

    ABS           Moulded parts                TV-sets/business machines,
                                               computer housings, household
                                               appliances (hairdryer, curler),
                                               automotive parts, electronics,
                                               telecommunications

    EPOXY         Circuit boards,              Computers, ship interiors,
                  protective coatings          electronic parts

    PAINTS/       Coatings                     Marine and industry lacquers
    LACQUERS                                   for protection of containers

    PHENOLICS     Printed circuit boards       Paper laminates/glass prepregs
                                               for printed circuit boards

    PAN           Panels, electrical           Lighting panels for elevators
                  components                   and rooms, housing of electrical
                                               appliances

    PA            Electrical connectors,       Computers, connectors,
                  automative interior          housing in electrical industry,
                  parts                        board, electrical connectors,
                                               automotive industry,
                                               transportation

    PBT           Electrical connectors        Switches, fuse, switch box,
                  and components               computer housings, switchboard
                                               electrical connectors,
                                               stereos, business machines,
                                               military electronics

    PE/XPE        Cross-linked wire and        Major application: power cable
                  cable, foam tubing,          with cross-linked low density
                  weather protection           PE; also used for conduit for
                  and moisture barriers        building with high density PE;
                                               Final uses: portable apparatus
                                               building control, instrument,
                                               shipboard, automotive, marine
                                               appliances, insulation of heating
                                               tubes

    PET           Electrical                   Boxes, relays, coils, bobbins
                  components
                                                                                             

    Table 5.  (cont'd).
                                                                                             

    Polymer       Principal applications       Examples of final products
                                                                                             

    PP            Conduits, electronic         TV and electronic devices, such
                  devices                      as yoke, housings, circuit board
                                               hangers, conduits; Final uses:
                                               electro-mechanical parts TV,
                                               hot waste water pipes,
                                               underground junction boxes

    PS, HIPS      TV cabinets and back         TV back panels, computer
                  covers, electrical           covers and housings of
                  appliance housings           electrical appliances, office
                                               machines, smoke detectors

    PVC           Cable sheets                 Wire end cables, floor mats,
                                               industrial sheets

    PUR           Cushioning materials,        Furniture, sound insulation
                  packaging, padding           panels, wood imitations,
                                               transportation

    RUBBER        Transportation               Conveyor belts, foamed pipes
                                               for insulation

    TEXTILES      Coatings                     Back coatings, impregnation:
                                               carpets, automotive seating,
                                               furniture in homes and official
                                               buildings, aircraft, undergrounds,
                                               tents, trains, and military
                                               safety clothing

    UPE           Circuit boards,              Electrical equipment, coatings
                  coatings                     for chemical processing plants
                                               mouldings, military and marine
                                               applications: construction
                                               panels
                                                                                             

    aFrom:  EBFRIP (1990).

    
    3.  FORMATION OF BROMINATED DIBENZOFURANS AND DIBENZODIOXINS FROM
        POLYBROMINATED DIPHENYL ETHERS

    3.1  General

        Polybrominated dibenzofurans (PBDF) and polybrominated
    dibenzodioxins (PBDD) can be formed from polybrominated diphenyl
    ethers, polybrominated phenols, and polybrominated biphenyls under
    different conditions, including heating (combustion). Laboratory
    experiments have also demonstrated the formation of PBDF and PBDD
    during the pyrolysis of certain other brominated flame retardants (see
    the EHC on  Brominated flame retardants, in preparation). As
    discussed in EHC 88:  Polychlorinated dibenzo-para-dioxins and
     dibenzofurans, there are hundreds of possible congeners of
    halogenated dibenzofurans and dibenzo-dioxins. However, only congeners
    with substituents in the 2,3,7,8-positions are of toxicological
    significance. In many reports, only the total levels of PBDF and PBDD
    are given, without regard to substitution pattern; such totals are of
    limited value in the estimation of possible risk.

        Hutzinger & co-workers investigated the pyrolysis of brominated
    flame retardants and flame retardant polymer systems and several
    publications have appeared. In general, the results reported showed
    that brominated dibenzofurans were observed at 700-800 °C and that the
    2,3,7,8-substituted compounds were seen in only low concentrations, if
    at all (Thoma et al., 1987a,b; Thoma & Hutzinger, 1987; Dumler et al.,
    1989).

        Shortly after the initial reports of Buser and Hutzinger, BFRIP
    and German chemical companies (Bayer, BASF, and Hoechst) and American
    industries independently reported the results of combustion and
    pyrolysis experiments with flame retarded polymers (BFRIP, 1990).

        Recently, brominated aromatic compounds have also attracted
    attention, since reports have appeared about emissions of PBDD and
    PBDF and other brominated and mixed halogenated aromatic compounds in
    accidental fires and from the combustion of waste (see section 4 of
    both DeBDE and OBDE).

        For more information on these pyrolysis experiments, see the
    different sections relating to the individual brominated diphenyl
    ethers, e.g., PeBDE, OBDE, and DeBDE.

        As an example, the formation of PBDF and PBDD from
    decabromodiphenyl ether is illustrated in Fig. 1.

    FIGURE 1

    3.2  Additional data on the pyrolysis of non-specified PBDE and/or
         polymers containing non-specified PBDE

        The earliest published work on the pyrolysis of brominated flame
    retardants was that of Buser, whose first paper appeared in 1986
    (Buser, 1986). Buser pyrolysed three technical PBDE mixtures with
    different degrees of bromination from commercial sources (pentabromo-,
    71% bromine; octabromo-, 79% bromine (predominantly hexa- to
    nonabrominated PBDE) and decabromo-, 83% bromine, 97% DeBDE) at
    510-630 °C in small quartz vials. The vials were placed in a heated
    oven for about one minute, and the contents analysed.

    A range of PBDD and PBDF was found with a total yield of up to 10%.
    HRGG/MS analysis revealed the formation of reasonably simple mixtures
    of reaction products with often one or two main PBDF- and
    PBDD-isomers. Debromination reactions lead to lower brominated PBDF
    and PBDD congeners. In general, the higher brominated PBDE lead to
    higher brominated PBDF and PBDD. Most likely, the PBDF and PBDD are
    formed in intramolecular cyclization reactions involving the attack by
    oxygen on the diphenyl ether system (Fig. 1) (Buser, 1986; Bieniek et
    al., 1989).

        The next report to appear in the literature was also in 1986 from
    the laboratory of Hutzinger. Hutzinger's group pyrolysed penta- and
    decabromodiphenyl ethers at 700, 800, and 900 °C, in a quartz tube
    oven, for about 10 min. They did not provide any isomer-specific
    results, but they reported the formation of PBDF and PBDD. Hutzinger
    continued to investigate the pyrolysis of brominated flame retardants
    and brominated flame retardant polymer systems, and several
    publications appeared (Thoma et al., 1987a,b; Thoma & Hutzinger, 1987;
    Dumler et al., 1989a). In general, the results reported in these
    publications were consistent with those of earlier work in that
    maximum concentrations of PBDF were observed at 700-800 °C and
    2,3,7,8-substituted compounds were seen only in very low
    concentrations, if at all.

        Shortly after the initial reports of Buser and Hutzinger, BFRIP
    and German chemical companies (Bayer, BASF and Hoechst) independently
    reported the results of combustion and pyrolysis experiments with
    flame retarded polymers.

        In the German work, pyrolysis studies were conducted with
    high-impact polystyrene/DeBDE, polypropylene/DeBDE, and ABS/OBDE
    (Neupert et al., 1989) (see also individual flame retardants). In all
    of these studies, the pyrolysis residues were analysed for the
    presence of PBDD and PBDF. While brominated PBDF were identified, only
    very small quantities of 2,3,7,8-TeBDF were observed (see Table 6)
    (BFRIP, 1990).

    Table 6.  Analytical results from the pyrolysis products of ABS/OBDE
              (Bayer)a
                                                                         

    Compound                             Concentration
                                                                         

                               Test 1 (ppm)         Test 2 (ppm)
                                                                         

    Brominated                    NDb                  NDb
    dibenzodioxins

    Brominated
    dibenzofurans:

    MBDF                          115                   60
    DiBDF                      10 000                 7500
    TrBDF                        8000                 2500
    TeBDF                        2000                 2500
    2,3,7,8-TeBDF                 < 0.1                < 8
    PeBDF                        1700                 2000
    HxBDF                         530                  470
    HpBDF                         < 1.4                 32
    OBDF                          < 3                  < 2.5
                                                                         

    aFrom:  BFRIP(1990).
    bND = Not detectable.

        Other brominated pyrolysis products of PBDE may be formed by
    cleavage and oxidation, including PBBz, phenol, and some naphthalenes.
    PBDF, however, may also be formed from small reactive species
    generated during PBDE cleavage (Umweltbundesamt, 1989; Buser, 1986)
    (see also the individual brominated diphenyl ethers).

        Striebich et al. (1991) examined gas phase oxidative and pyrolysis
    thermal decomposition of a 1:1 percentage weight mixture of two
    commercial polybrominated diphenyl ether products (tri- through
    deca-bromination). The gas phase material was quantitatively
    transported to a quartz thermal reactor and subjected to a series of
    controlled time/temperature exposures (300-800 °C for 2.0 seconds) in
    either air or a nitrogen atmosphere. Thermal decomposition products
    were identified. Isomers with higher levels of bromination were
    generally more stable than lower brominated diphenyl ethers, under
    both oxidative and pyrolytic conditions. Table 7 shows the approximate
    yields of products from brominated diphenyl ethers. At 800 °C, all
    products were decomposed to HBr or non-detectable products, in both
    air and nitrogen. Neither PBDF/PBDD nor any parent material could be
    detected at this temperature.

    Table 7.  Thermal decomposition products from a mixture of two
              commercial PBDE (1:1 w/w)a
                                                                         

    Product                                  Maximum yield (%)

                                     Nitrogen (650 °C)     Air (625 °C)
                                                                         

    Dibromobenzenes                       0.35                 NDc
    Tribromobenzenes                      0.64                0.92
    Tetrabromobenzenes                    0.43                0.95
    Unknown (pentabromobenzenes?)         0.04                0.24
    Brominated alkanes, alkenes,          1.40                0.77
    and other PICsb

    DiBDF                                 0.03                 NDc
    TrDBF                                 0.03                0.03
    TeBDF                                 0.03                0.03
    DiBDD                                  NDc                0.04
    TrBDD                                  NDc                0.04
    TeBDD                                  NDc                0.01
                                                                         

    aFrom:  Striebich et al. (1991).
    bPICs = Products of incomplete combustion.
    cND = Not detectable.

    4.  WORKPLACE EXPOSURE STUDIES

    4.1  Exposure to PBDE

        Inhalation exposure to brominated diphenyl ethers is expected to
    be low, since the vapour pressure of these chemicals is in the range
    of 10-7 mmHg. Particulates in the respirable range are expected to be
    formed during the grinding of solids. As inhalation of dust is
    possible, the use of dust respirators and gloves/goggles is
    recommended in areas of potential exposure.

        Dermal exposure may occur during filtration, drying,
    drumming/bagging, size reduction, and maintenance (US EPA, 1986).

        Exposure to these compounds can also take place during processing
    (incorporation into various polymers) and the use of the polymer blend
    to fabricate the final articles. After processing, the resin is
    generally in the form of pellets rather than powder. Exposure is
    expected to be low at fabrication sites because of the low vapour
    pressure and of ventilation controls (US EPA, 1986).

    4.2  Exposure to PBDF/PBDD

        Workers may be exposed to PBDF/PBDD during the production and
    processing of plastics containing PBDE as flame retardants and of
    products made from them. In addition, workers and the general
    population may be exposed to PBDF/PBDD when products, particularly
    from the electrical, electronic, and computer industries, emit
    PBDF/PBDD during normal operations (see section 4 of both DeBDE and
    OBDE).

        The PBDF/PBDD contents of component parts taken from 6 electrical
    appliances (including printers, TV sets, and computer terminals) as
    well as two casings were determined. PBDF/PBDD were detected in 16 of
    the materials; mainly higher brominated PBDF at concentrations of
    between 0.007 and 4.2 mg/kg (sum of MBDF to HxBDF/MBDD to HxBDD) were
    found (Hamm & Theisen. 1992).

        Determination of PBDE and PBDF concentrations in air and dust
    samples were made in offices having a large number of TV or computer
    monitors in operation: the police traffic control office in Hamburg
    (47 monitors; room 100 m2, 6 m high, 23 °C) and three rooms of a
    television company with monitors (20 °C).

        In the police traffic control office, air samples were taken for 3
    days at a level of 1.5 m above the floor, a total of 84 m3 air being
    drawn, and analysed. Dust samples were taken from the monitors from a
    total surface of 3 × 10 m (39 g).

        In the first room of a television company (50 m2), where 58
    monitors were in use, a total of 129 m3 air was taken over 5 days. In
    the second room (40 m2),where 38 monitors were in use, 126 m3 air
    was taken, while in the third room (30 m2), where 42 monitors were in
    use, 145 m3 air was taken. Dust samples were also collected once a
    day from all rooms using a vacuum cleaner.

        The concentrations in air of the police station and the television
    company ranged between 0.29 and 1.27 pg PBDF/m3 and 97 pg PBDE/m3.
    Indoor dust contained PBDF at low ppb and PBDE at high ppb levels.
    2,3,7,8-substituted PBDF were not detected (limit of determination
    between 0.3 and 0.1 µg/m3) (Ball et al., 1992).

    5.  EXPOSURE OF THE GENERAL POPULATION

    5.1  General population

        Limited information is available on the exposure of the general
    population to brominated diphenyl ethers. Uptake of TeBDE and PeBDE
    may occur in humans via the foodchain, e.g., by consuming fish. In
    Germany, PBDE has been detected in human and cow's milk at levels of
    2.6 and 3 µg/kg fat, respectively (Kruger, 1988).

        Remmers et al. (1990) found evidence of the occurrence of
    polychlorinated diphenyl ethers (PCDE) and PBDE in human adipose
    tissue specimens from the USA, during the analysis of these tissues
    for dioxins and furans. The results showed the presence of HxBDE/HxCDE
    through to DeBDE/DeCDE in the tissues analysed.

        The presence of brominated diphenyl ethers was indicated in all of
    the 47 samples analysed (Cramer et al., 1990a,b). The human samples
    were composites derived from all parts of the USA and covering ages
    ranging from birth to > 45 years. Additional work is needed to
    confirm the presence of these compounds, which have been found
    provisionally in the following frequencies and concentrations; HxBDE
    (72%; nd-1000 ng/kg); HpBDE (100%; 1-2000 ng/kg) and OBDE (60%;
    nd-8000 ng/kg). DeBDE was found in only a few samples at
    concentrations of 0.4-0.7 ng/kg.

    Exposure may also mainly occur through skin contact (flame retardants
    in polymers used in textiles), but also via inhalation (release of
    flame retardants from the polymer matrix) (US EPA, 1986).

    5.2  Possible exposure to PBDE and PBDF/PBDD

    5.2.1  Television sets

        Studies were carried out to determine whether PBDF escape from TV
    sets. Four air samples (2 parallel to each other) were taken over 3
    days in a closed room (volume 26.8 m3), where a new TV set was
    operating for 17 h/day. The surface temperature of the TV set (back
    panel) was 38-40 °C. One sampling was performed above the TV set,
    while the others were carried out in the centre of the room (2.2 m
    from the TV set). The levels in the centre of the room of tri-,
    tetra-, penta-, and hexabromo-dibenzofurans were 25, 2.7, 0.5, and
    0.1 µg/m3, respectively (levels in outdoor air ranged from < 0.05 to
    0.16 µg/m3). Above the TV set, the concentrations of the 4 PBDF were
    143, 11, 0.5, and < 0.1 µg/m3. Hepta- and octabromodibenzofuran, and
    poly-brominated dibenzodioxins were not found (limits of determination
    0.1 and 0.2 µg/m3, respectively) (Bruckmann et al., 1990).

        An investigation was conducted to determine the emissions of PBDE
    and PBDF from plastics in two TV sets, one colour and one monochrome,
    two computer monitors, and three printers, under conditions of use.
    Analytical methods were refined to obtain a reliable determination of
    PBDF. Each appliance was placed, under conditions of use, in a test
    chamber. The volume of the steel chamber was 1.17 m3 (1.5 × 1.07 ×
    0.82m). For three days, pure air was continuously drawn through the
    chambers at a rate of 1.5 m3/h; the emitted compounds were absorbed

    on a sampler for the subsequent extraction and determination of PBDE
    and PBDF with 4 or more bromines. PBDF concentrations were found to
    vary between not detected (limit of detection 3-10 pg) and 1799 pg per
    appliance tested and PBDE concentrations, between 0.4 and
    889 ng/appliance; 2,3,7,8 isomers (1070 µg/appliance) were detected
    only from the colour TV set (Ball et al., 1991).

        Three new television sets were placed in a 1.81 m3 test chamber.
    Two of the cabinets were made from polystyrene, which was flame
    retarded with 11.5% DeBDE. The third television set was made of
    high-impact polystyrene, treated with DeBDE/Sb2O3 as a flame
    retardant. PBDF and PBDD concentrations were determined in air
    collected over 3 days while the two television sets were operating and
    during one day when the third TV set was operating. The concentrations
    of TeBDD, PeBDD, TeBDF, and PeBDF ranged between 0.09 and 1.52 µg/m3
    (Ranken et al., 1990).

    5.2.2  Fire tests and fire accidents

        Six appliances and 2 casings were burned in a fire test room
    (floor area 21 m2, volume 48 m3), which was kept closed during the
    fire tests and slowly ventilated after extinguishing the fires (worst
    case conditions). After the fire test, samples of combustion residues
    and smoke condensate were taken. Smoke was collected in 5 tests. The
    combustion residues showed the presence of PBDF and PBDD in
    concentrations ranging between 1 and 1930 mg/kg and from the casing
    components almost 1%. Smoke condensate from contaminated surfaces
    contained levels of between 6 and 1610 µg monobromo- up to
    hexabromodibenzofuran/dibenzodioxin per m2. Smoke contained
    11-1700 µg monobromo- up to hexabromo- dibenzofuran/dibenzodioxin per
    m3 (see Table 8) (Hamm & Theisen, 1992).

        Residues and smoke condensates resulting from actual fire
    accidents with 9 TV sets were examined. PBDF/PBDD concentrations in
    the residues were mainly in the µg/kg range, one value being
    107 mg/kg. Close to the fire site, the PBDF/PBDD area contamination
    concentrations were between 0.1 and 13.1 µg/m3 (see Table 9) (Hamm &
    Theisen, 1992).

        It was concluded that the levels of PBDF/PBDD produced in real
    fires are much lower than those produced under fire-test conditions.


        Table 8.  PBDF/D concentrations in original components of electrical appliances and in samples from fire tests with these
              appliances or with their casingsa
                                                                                                                                

    Object of investigation                      Original components                        Fire test samples
                                                                                                                                

                                            Casings       Printed circuit     Combustion          Smoke            Smoke
                                                              boards           residues        condensate
                                                                                                                                
                                        Total mono- to    Total mono- to    Total mono- to   Total mono- to    Total mono-to
                                        hexaBDF/D µg/g    hexaBDF/D µg/g       hexaBDF/D        hexaBDF/D        hexaBDF/D
                                             (ppm)             (ppm)          µg/g (ppm)          µg/m2            µg/m3
                                                                                                                                

    Casing of electrical appliance 1       0.63              -b                  8700              177                -b
    Casing of electrical appliance 2       0.64              -b                  7750             1610                -b
    Electrical appliance 3                 -c                1.77                 468              106               456
    Electrical appliance 4                 0.06              3.44                  43              260               355
    Electrical appliance 5                 0.81              1.98                  18              396              1700
    Electrical appliance 6                 4.20              0.35                1930              234              1350
    Etectrlcal appliance 7                 -c                0.13                   1                6                11
    Electrical appliance 8                 1.26              0.007                 24              323                -b
                                                                                                                                

    aFrom: Hamm & Thiesen (1992).
    b = Not determined.
    c = Not detectable.

    

    Table 9.  PBDF/D-concentrations in residues and smoke condensates from
              real fire accidents with television setsa
                                                                         

    Fire accident    Combustion               Smoke condensates
    (Case number)     residues
                                                                         

                                    Close to fire site       At some
                                                          distance from
                                                            fire site
                                                                         

                   Total mono- to     Total mono- to     Total mono- to
                      hexaBDF/D          hexaBDF/D          hexaBDF/D
                     µg/g (ppm)            µg/m2              µg/m2
                                                                         

    I                  0.235              10.7                0.665
    II                 0.004               0.134              0.102
    III                0.209              13.1                0.382
    IV                 0.009              NDb                 NDb
    V                  0.001               4.82               1.39
    VI                 0.017               0.759              0.425
    VII                0.001               0.021              0.008
    VIII               0.001              10.5                5.37
    IX               107                   7.47               0.847
                                                                         

    aFrom:  Hamm & Thiesen (1992).
    bND = Not detectable.

    6.  ENVIRONMENTAL POLLUTION BY PBDE

    6.1  Ultimate fate following use

        Products containing PBDE are disposed of in the normal domestic
    waste stream (landfill and incineration).

        No studies are available on the fate of PBDE-containing products
    in landfills, but there is concern that the PBDE may eventually leach
    out. Bearing in mind that PBDE, at least the congeners with more than
    3 bromine atoms, are persistent in the environment, the introduction
    of such chemicals into widespread products may be a considerable
    long-term diffuse source of emissions of these compounds to the
    environment. This type of source is difficult to control and the
    unnecessary use of persistent organic compounds should be avoided.

        Formation of PBDF and/or PBDD as a result of landfill fires is
    also a possibility, though no data are available on the scale of this
    source. The results of pyrolysis experiments showed that PBDE can form
    PBDF and PBDD (in much smaller quantities) under a wide range of
    heating conditions (see General Introduction sections 3.1 and 3.2). If
    chlorine is present, mixed halogenated furans/dioxins can also be
    generated (Oberg et al., 1987; Zier et al., 1991). Unless sufficiently
    high temperatures and long residence times are maintained, PBDF/PBDD
    can be generated during the incineration of products containing PBDE.
    They can also result from poorly-controlled combustion gas cooling.
    Modern, properly operated municipal waste incineration (MWI) should
    not emit significant quantities of PBDF/PBDD, regardless of the
    composition of the municipal waste.

        Lahl et al. (1991) reported increases in dibenzofuran and
    dibenzodioxin levels in filter dust, when products containing PBDE
    were added to the feed-stock. Riggs et al. (1990) reported PBDF
    generation when a flame retarded resin was burnt under simulated MWI
    conditions. However, Oberg et al. (1987) reported no increased
    emissions of dibenzodioxins when the bromine content of an
    incineration feed-stock was increased. Monobromodichloro-dibenzofuran
    levels were slightly increased. Oberg & Bergström (1990) conducted
    further experiments with a hazardous waste incinerator, to study the
    relationship between bromine levels in municipal waste and incinerator
    dibenzodioxin and dibenzofuran emissions. They concluded that no
    unacceptable environmental risks were associated with the incineration
    of brominated compounds in plants with good combustion conditions
    equipped with efficient flue gas cleaning. They further noted that
    only 0.0125% of the feed to Swedish MWIs was brominated waste.

    6.2  Air

        Watanabe et al. (1992) reported on the presence of PBDE in the air
    in Taiwan and Japan. The concentrations in the air samples collected
    in Taiwan from a recycling plant in January 1991 were, in general,
    higher than those in Japan; 3 samples were analysed in Taiwan, and 5
    in Japan. Tribromo-, tetrabromo-, pentabromo-, and hexabromodiphenyl
    ethers were present in the following mean concentrations: Taiwan, 32,
    52, 23, and 31 µg/m3, and, Japan, 7.1, 21, 8.9, and 21 µg/m3,
    respectively.

    6.3  Soil

        Two ash and two soil samples were collected in Taiwan from a
    recycling plant in January 1991 and analysed for the presence of PBDE.
    Tri-, tetra-, penta-, hexa-, and decabromodiphenyl ethers were present
    in ash in the following concentrations 20-20, 130, 78-110, 47-54, and
    510-2500 µg/kg, respectively; the concentrations in soil were 38-40,
    75-104, 41-84, 20-23 and 260-330 µg/kg, respectively. Hepta- and
    octabromodiphenyl ether were not found (Watanabe et al., undated).

    6.4  Water

        Marine, estuarine, and river water samples were analysed for the
    presence of the different PBDE. Except for monobromo-diphenyl ether,
    levels of all the higher brominated PBDE were below the detection
    limit. MBDE was mainly found in the surroundings of manufacturing
    plants in the USA (US EPA, 1986).

    6.5  Sediments and sewage sludge

        In Japan, Spain, Sweden, and the USA, studies were carried out to
    determine the presence of the different PBDE in marine, estuarine, or
    river sediment. PBDE were mainly found in river sediment. In general,
    the levels were below 100 µg/kg dry weight, except in rivers in the
    vicinity of manufacturing plants. In these cases, the concentrations
    were much higher. In a river in Sweden, concentrations of 11.5 mg
    DeBDE, 0.8 mg TeBDE, and 2.8 mg PeBDE/kg dry weight were found. In the
    USA, at a manufacturing plant, as much as 1 g DeBDE/kg was found
    (Zweidinger et al., 1978; DeCarlo, 1979; Environment Agency Japan,
    1983, 1989, 1991; Watanabe et al., 1986, 1987b; Fernandez et al.,
    1992).

        The upper layers in a laminated sediment core from the Baltic Sea
    (Bornholm Deep) contained higher levels of TeBDE and PeBDE than the
    deeper layers, indicating an increasing burden of these compounds
    (Nylund et al., 1992).

        A series of samples of sewage sludges from municipal waste water
    treatment plants in Germany were analysed for poly-halogenated
    compounds, such as halogenated diphenyl ethers. Tribromo- to
    heptabromodiphenyl ethers were found at relatively high concentrations
    (Hagenmaier et al., 1991). Sewage sludge was analysed in Sweden for
    the presence of TeBDE and PeBDE. Concentrations of 15 and 19 µg/kg,
    respectively, were found (Sellström et al., 1990a,b).

    6.6  Aquatic vertebrates

        The presence of PBDE depends mainly on the degree of bromination.
    DeBDE, OBDE, and HxBDE were not found in mussel and fish samples
    collected in Japan. No data are available for HpBDE. However, PeBDE
    was found in mussel and fish species in concentrations of < 3 µg/kg
    wet weight in Japan. Concentrations of 22 µg 2,2',4,4',5-PeBDE/kg wet
    weight were found in cod liver collected in the North Sea, and
    concentrations of up to 64 µg/kg on a fat basis were found in fish
    collected in Sweden. The concentrations were much higher in fish
    collected in the vicinity of industrial areas, e.g., up to 9.4 mg/kg
    on a fat basis (Jansson et al., in press). Levels for TeBDE, mainly
    2,2',4,4'-TeBDE, were comparable but generally higher. Mussels and

    fish in Japan contained up to 14.6 µg/kg wet weight, cod liver
    collected in the North Sea, 360 µg/kg, and eel from the Netherlands,
    up to 1700 µg/kg fat. Different species of fish collected in Sweden
    contained up to 88 mg/kg fat (Andersson & Blomkvist, 1981; Watanabe,
    1987; Watanabe et al., 1987b; De Boer, 1989, 1990). An increasing
    trend was observed in PeBDE and TeBDE levels in freshwater fish in
    Sweden. Only limited data are available concerning lower brominated
    PBDE (Jansson et al., in press).

        Thirty-five samples of 18 freshwater fish collected in German
    rivers, and 17 samples collected from the Baltic Sea and the North Sea
    contained 18.2-983.6 and 0.6-119.9 µg PBDE/kg fat (determined as
    Bromkal 70-SDE), respectively (Kruger, 1988).

    6.7  Aquatic mammals

        Three bottle-nose dolphins  (Tursiops truncatus), collected
    during the 1987/88 mass mortality event along the central and south
    Atlantic coast of the USA, were analysed for brominated diphenyl
    ethers. The concentrations of PBDE were 200, 220, and 180 µg/kg lipid
    (Kuehl et al., 1991).

        Limited data are available on the presence of PBDE in aquatic
    mammals. 2,2'4,4'5-PeBDE was found in ringed and grey seals, collected
    in Sweden, in concentrations of 1.7 and 40 µg/kg fat, respectively.
    TeBDE, mainly 2,2',4,4'-TeBDE, was also found in the blubber of these
    2 species in concentrations of 47 and 650 µg/kg fat, respectively
    (Jansson et al., in press). Seals collected at Spitzbergen contained
    approximately 10 µg PBDE/kg fat, determined as Bromkal 75DE (Kruger,
    1988).

    6.8  Terrestrial vertebrates

        Pooled samples of rabbits, moose, and reindeer, collected in
    Sweden, contained PeBDE and TeBDE in concentrations of <0.3, 0.64,
    and 0.26 µg 2,2',4,4',5-PeBDE/kg and <2, 0.82, and 0.18 µg
    2,2',4,4'-TeBDE/kg lipid, respectively (Jansson et al., in press).

        Four samples of cow's milk were analysed in Germany for the
    presence of PBDE. The average concentration was 3.572 µg/kg fat (range
    2.536-4.539 µg/kg) determined as Bromkal 70-5DE. The main component
    was HxBDE (Kruger, 1988).

    6.8.1  Birds

        Limited data are available on the presence of PBDE in birds. In
    Sweden, 2,2',4,4',5-PeBDE was found in the muscle tissue of osprey, in
    newborn starlings, and in guillemot eggs in concentrations of 140,
    2.3-4.2, and 24-260 µg/kg lipid, respectively. A trend towards
    increasing concentrations of PeBDE and TeBDE in guillemot eggs from
    the Baltic Sea was observed. 2,2',4,4'-TeBDE was found in the muscle
    tissue of osprey in concentrations of up to 1800 µg/kg. Guillemots
    collected from the Baltic Sea, the North Sea, and Spitzbergen
    contained 370, 80, and 130 µg/kg on a fat basis, respectively (Jansson
    et al., 1987, 1993).

        In the USA, indications were found that dibromodiphenyl ether was
    present in the eggs of fish-eating birds, but it was not quantified
    (Stafford, 1983).

    6.8.2  Humans

        In Germany, 25 samples of breast milk were analysed for the
    presence of PBDE. The ages of the women ranged between 24 and 36 years
    and most of them were breast-feeding their first or second child. The
    samples contained 0.6-11.1 µg PBDE/kg fat, determined as Bromkal
    70-5DE. The main component was HxBDE. One sample from a Chinese woman
    showed 7.7 µg PBDE/kg fat; a sample from another woman, exposed
    occupationally to hydraulic fluids and transformer oils, contained
    50 µg PBDE/kg fat. This last value was excluded from the given range
    and average. (Kruger, 1988).

    DECABROMODIPHENYL ETHER

    1.  SUMMARY, EVALUATION, CONCLUSIONS, AND RECOMMENDATIONS

    1.1  Summary and evaluation

    1.1.1  Identity, physical and chemical properties

    Typically, commercial DeBDE has a purity of 97-98%, with 0.3-3.0% of
    nona- and/or octabrominated diphenyl ethers. Nonabromodiphenyl ether
    (NBDE) is the major impurity. In contrast to the other polybrominated
    diphenyl ethers there is only one isomer of DeBDE.

    The melting point of DeBDE is approximately 300 °C and decomposition
    occurs above 400 °C. Solubility in water is 20-30 µg/litre and the log
    of the  n-octanol/water partition coefficient is greater than 5.
    Vapour pressure is < 10-6 mmHg at 20 °C.

    1.1.2  Production and uses

    Among the brominated diphenyl ethers (mono- to deca-),
    deca-bromodiphenyl ether is the most important commercial product with
    regard to production and use.

        Commercial DeBDE has been produced in increasing degrees of purity
    since the late 1970s. The global production of DeBDE is approximately
    30 000 tonnes/year. It is used as an additive flame retardant in many
    plastics, especially high-impact polystyrene, and in the treatment of
    textiles used in soft furnishing, automobile fabrics, and tents.

    1.1.3  Environmental transport, distribution, and transformation

        Photodegradation of DeBDE occurs in organic solvents under
    ultraviolet radiation (UVR) or sunlight; lower brominated diphenyl
    ethers and brominated dibenzofurans are formed. Photodegradation also
    occurs, to a lesser extent, in water with sunlight; however, lower
    brominated diphenyl ethers and brominated dibenzofurans have not been
    found.

        Levels of DeBDE extracted from polymers are close to, or below,
    the limit of detection, depending on the polymer type and extraction
    solvent.

        Because of its extremely low water solubility and vapour pressure,
    DeBDE is likely to be transported primarily by adsorption to
    particulate matter. It is persistent and likely to accumulate in
    sediment and soil.

        No data are available on its bioavailability from sediment and
    soil. A study on rainbow trout did not show any bioaccumulation in
    flesh, skin, or viscera, over 48 h. DeBDE is unlikely to bioaccumulate
    because of its high relative molecular mass.

        Products containing commercial DeBDE will eventually be disposed
    of by landfill or incineration. DeBDE may eventually leach from
    landfills. Polybrominated dibenzofurans (PBDF) and mixed
    halogen-dibenzofurans and -dibenzodioxins may result from landfill
    fires and inefficient incineration. Products containing commercial
    DeBDE may contribute to these emissions.

        Pyrolysis of both commercial DeBDE itself and polymers (HIPS, PBT,
    industrial polypropylene) containing DeBDE, in the presence of oxygen,
    produced PBDF, polybrominated dibenzodioxins (PBDD) being found to a
    lesser extent. The maximum formation' of PBDF occurs at 400-500 °C,
    but it can occur at temperatures up to 800 °C, and Sb2O3 plays a
    catalytic role in the formation of PBDF and PBDD.

        The formation, and amounts found, of PBDF and PBDD depend on
    temperature, oxygen content, and length of pyrolysis. In the absence
    of oxygen, mainly polybromobenzenes and polybromonaphthalenes are
    formed.

    1.1.4  Environmental levels and human exposure

        DeBDE has been identified in air in the vicinity of manufacturing
    plants at concentrations of up to 25 µg/m3. DeBDE was not detected in
    water samples collected in Japan in the period 1977-91. However, it
    was detected in river and estuarine sediment, collected in Japan in
    the same period, at concentrations of up to approximately 12 mg/kg dry
    weight. DeBDE (up to 1 g/kg) was also found in the USA in river
    sediment close to one manufacturing plant. DeBDE was not detected in
    fish samples collected in Japan, but, in one mussel sample, a level
    just above the level of detection was found. DeBDE was not detected in
    human adipose tissue samples collected in Japan, but, in the USA,
    DeBDE was found in 3 out of 5 samples of human adipose tissue.

        Human exposure to DeBDE can occur in the course of manufacture and
    formulation into polymers. Exposure of the general population to DeBDE
    is insignificant.

        Determination of occupational exposure to the breakdown products
    of DeBDE during manufacture, formulation, or use, showed that air
    samples close to the extruder head contained high concentrations of
    PBDF. Lower levels were found in the air of the workroom. PBDF was
    also found in wipe samples. The application of good engineering
    techniques has been shown to reduce occupational exposure to PBDF.

        Exposure of, the general population to PBDF impurities in flame
    retarded polymers is unlikely to be of significance.

    1.1.5  Kinetics and metabolism in laboratory animals and humans

        DeBDE is poorly absorbed from the gastrointestinal tract and is
    rapidly excreted following injection.

        The results of metabolic studies on the rat, using 14C labelled
    DeBDE, indicated a half-life for the disappearance from the body of
    less than 24 h and that the principal route of elimination following
    oral ingestion was via the faeces. No appreciable 14C activity (less
    than 1%) was found in either urine or expired air.

        Rats fed 0.1 mg/kg body weight per day, for up to two years,
    showed no accumulation of DeBDE in serum, kidneys, muscle, or testes,
    as estimated from total bromine determination. Bromine accumulation in
    the liver plateaued at 30 days and was cleared within 10 days
    following treatment. After 180 days of treatment, the bromine level in
    the liver of treated rats was no greater than that in control rats.
    Adipose tissue accumulated low levels of total bromine, which remained
    after 90 days of clean diet; the nature of the retained "bromine" is
    not known. Since DeBDE accounted for only 77% of the commercial
    mixture used, "bromine" could have been derived from NBDE or OBDE.

    1.1.6  Effects on laboratory mammals and  in vitro test systems

        The acute toxicity of DeBDE for laboratory animals is low. The
    substance is not an irritant to the skin or eyes of rabbits. It is not
    chloracnegenic on the skin of rabbits and is not a human skin
    sensitizer.

        The combustion products of flame retarded polystyrene containing
    DeBDE and Sb203 were tested for acute toxicity and comedogenicity.
    The rat oral LD50 of the soot and char was >2000 mg/kg body weight.

        In short-term toxicity studies on rats and mice, DeBDE (purity
    >97%) at dietary levels of 100 g/kg (4 weeks) or 50 g/kg (13 weeks;
    equivalent to 2500 mg/kg body weight for the rat) did not induce
    adverse effects. A one-generation reproduction study on rats showed no
    adverse effects with dose levels of 100 mg/kg body weight. DeBDE did
    not cause any teratogenic effects in the fetuses of rats administered
    a dose level of 100 mg/kg body weight. With 1000 mg/kg body weight,
    malformations, such as delayed ossification, were seen. DeBDE was not
    shown to be mutagenic in a number of tests.

        In a carcinogenicity study on rats and mice, DeBDE (purity 94-99%)
    was administered at dietary levels of up to 50 g/kg. An increase in
    the incidence of adenomas (but not carcinomas) was found in the livers
    of male rats receiving 25 g/kg and female rats receiving 50 g

    DeBDE/kg. In male mice, increased incidences of hepatocellular
    adenomas and/or carcinomas (combined) were found at 25 g/kg and an
    increase in thyroid follicular cell adenomas/ carcinomas (combined) at
    both dose levels. Female mice did not show any increase in tumour
    incidence. There was equivocal evidence for carcinogenicity in male
    and female rats and male mice only at dose levels of 25-50 g DeBDE/kg
    diet. As the results of all mutagenicity tests have been negative, it
    can be concluded that DeBDE is not a genotoxic carcinogen. IARC (1990)
    concluded that there was limited evidence for the carcinogenicity of
    DeBDE in experimental animals. The very high dose levels, lack of
    genotoxicity, and minimal evidence for carcinogenicity indicate that
    DeBDE, at the present exposure levels, does not present a carcinogenic
    risk for humans.

    1.1.7  Effects on humans

        No evidence for skin sensitization was found in 200 human subjects
    exposed to DeBDE in a sensitization test.

        A morbidity study of extruder personnel blending
    polybutyl-eneterephthalate containing DeBDE, with consequently
    potential exposure to PBDD and PBDF for 13 years, did not reveal any
    deleterious effects, even though 2,3,7,8-TeBDF and -TeBDD were
    detected in the blood. Results of immunological studies showed that
    the immune system of the exposed persons was not adversely affected in
    13 years.

    1.1.8  Effects on other organisms in the laboratory and field

        The EC50s for the growth of 3 marine unicellular algae were
    greater than 1 mg DeBDE/litre. No further information is available on
    the effects of DeBDE on other organisms in the laboratory and field.

    1.2  Conclusions

    1.2.1  DeBDE

        DeBDE is widely used incorporated in polymers as an additive flame
    retardant. Contact of the general population is with products made
    from these polymers. Exposure is very low since the DeBDE is not
    readily extracted from polymers. The acute toxicity of DeBDE is very
    low and there is minimal absorption from the gastrointestinal tract.
    Thus, risk to the general population from DeBDE is considered to be
    insignificant.

        Occupational exposure is to DeBDE in particulate form. The control
    of dust during manufacture and use will adequately reduce the risk for
    workers.

        DeBDE is persistent and binds to particulate matter in the
    environment; it is likely to accumulate in sediment. It is unlikely to
    bioaccumulate. Current evidence suggests that environmental
    photodegradation in water does not lead to the formation of lower
    brominated diphenylethers or brominated dibenzofurans, but little is
    known about degradation in other media.

        There is minimal information on the toxicity of DeBDE for
    organisms in the environment.

    1.2.2  Breakdown products

        Formation of PBDF and, to some extent, PBDD may occur when DeBDE,
    or products containing it, are heated to 300-800 °C. The possible
    hazards associated with this have to be addressed.

        Properly controlled incineration does not lead to the emission of
    significant quantities of brominated dioxins and -furans. Any
    uncontrolled combustion of products containing DeBDE can lead to an
    unquantified generation of PBDF/PBDD. The significance of this for
    both humans and the environment will be addressed in a future
    Environmental Health Criteria on PBDF/PBDD.

        PBDF have been found in the blood of workers involved in the
    production of plastics containing DeBDE. No adverse health effects
    have been associated with this exposure. Good engineering controls can
    prevent worker exposure to PBDF.

    1.3  Recommendations

    1.3.1  General

    *   Workers involved in the manufacture of DeBDE and products
        containing the compound should be protected from exposure through
        the application of appropriate industrial hygiene measures, the
        monitoring of occupational exposure, and engineering controls.

    *   Environmental exposure should be minimized through the appropriate
        treatment of effluents and emissions in industries using the
        compound or products. Disposal of industrial wastes and consumer
        products should be controlled, to minimize environmental
        contamination with this persistent material and its breakdown
        products.

    *   Manufacturers should minimize levels of impurities in commercial
        DeBDE products, using the best available techniques. A purity of
        97% or higher is recommended.

    *   Incineration should only be carried out in properly constituted
        incinerators, running at consistently optimal conditions. Burning
        by any other means may lead to the production of PBDF and/or PBDD.

    1.3.2  Further studies

    *   Further studies on the bioavailability and toxicity of
        sediment-bound DeBDE should be performed on relevant organisms.

    *   Continued monitoring of environmental levels is required.

    *   The generation of PBDF under real fire conditions should be
        further investigated.

    *   Environmental biodegradation, and photodegradation in compartments
        other than water, should be further studied.

    *   Investigation into possible methods and consequences of recycling
        of DeBDE-containing polymers should be made.

    *   Analytical methods for DeBDE in various matrices should be
        validated.

    2.  IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, ANALYTICAL METHODS

    2.1  Identity

    2.1.1  Pure substance

           Chemical structure:

    CHEMICAL STRUCTURE 2

    Chemical formula:             C12Br10O

    Relative molecular mass:      959.22

    Chemical name:                decabromodiphenyl ether
                                  (DeBDE); decabromodiphenyl
                                  oxide

    CAS registry number:          1163-19-5
                                  (61345-53-7, mixture of
                                  decabromodiphenyl oxide and
                                  Sb2O3)

    CAS name:                     1,1'-oxybis[2,3,4,5,6-pentabromo]-
                                  benzene

    IUPAC name:                   bis(pentabromophenyl) ether

    EINECS registry number:       214604

    MITI number:                  3-2846

    Synonyms:                     decabromobiphenyl ether;
                                  decabromobiphenyl oxide;
                                  Decabrom; ether,
                                  bis(pentabromophenyl);
                                  ether, decabromodiphenyl

        From: US EPA (1984); Ethyl Corp. (1992a).

        On the basis of the chemical structure, decabromodiphenyl ether is
    fully brominated and there is only one congener.

    2.1.2  Technical product

    Trade names:                  FR-300 BA; DE-83-RTM; Saytex
                                  102; Saytex 102E; FR-1210;
                                  Adine 505; AFR 1021;
                                  Berkflam B10E; BR55N;
                                  Bromkal 81; Bromkal 82-ODE;
                                  Bromkal 83-10 DE; Caliban
                                  F/R-P 39P; Caliban F/R-P 44;
                                  Chemflam 011; DE 83; DP 10F;
                                  EB 10FP; EBR 700; Flame Cut
                                  BR 100; FR 300BA; FR P-39;
                                  FRP 53; FR-PE; FR-PE(H);
                                  Planelon DB 100; Tardex 100;

    Trade names (contd)           NC-1085; HFO-102; Hexcel PF1;
                                  Phoscon Br-250; NCI-C55287
                                  Caliban-F/RP-44 is a DeBDE
                                  mixture with antimony oxide,
                                  and, F/RP-53 contains 60% DeBDE,
                                  which is used in conjunction with
                                  THP-salts finishes and an acrylic
                                  binder.

        Commercial DeBDE is typically composed of 97-98% decabromodiphenyl
    ether with 0.3-3.0% other brominated diphenyl ethers (BFRIP, 1990)
    (see Table 1). Nonabromodiphenyl ether isomers are the major
    impurities. The commercial product typically contains a minimum of
    81-83% bromine (IARC, 1990) (83% theoretical; Ethyl Corp. 1992a).

        Differences in manufacturing processes affect the nature and
    amounts of impurities in the product (Larsen, 1980). Today's
    commercial product is considerably purer than that manufactured in the
    past. Isomers of nonabromodiphenyl ether and octabromodiphenyl ether
    have been reported as impurities in DeBDE (Timmons & Brown, 1988).
    FR-300-BA, produced in the early 1970s (no longer a commercial
    product), was composed of 77.4% DeBDE, 21.8% NBDE, and 0.8% OBDE
    (Norris et al., 1975c). Later production of DeBDE, by the same
    manufacturer, ranged in composition from 94 to 99% DeBDE with 0.3-4.5%
    impurities (NBDE isomers were identified as the major impurities)
    (NTP, 1986). Other DeBDE products, e.g., DE-83, Saytex 102E, and
    Bromkal 82-ODE have a purity of approximately 93 to 98.5% with
    different quantities of impurities (Dow Chem. Comp., 1978; De Kok et
    al., 1979; Davidson & Ariano, 1986).

        The availability of a technical product (possibly FR-1208) of
    88.1% purity containing 11% nona-, and 0.5% octabromodiphenyl ether,
    and 0.1% hexabromobenzene has been reported (Klusmeier et al., 1988).

        In Japan, a DeBDE is produced containing about 3% of
    nonabromodiphenyl ether as an impurity (Watanabe & Tatsukawa, 1987).

    2.2  Physical and chemical properties

        Commercial DeBDE is a free-flowing, odourless, off-white powder,
    with a bromine content of 81-83% and a high melting point.

    Melting point:                290-306 °C

    Decomposition point,          >320, >400, and 425 °C
    DTA                           (different products)

    Volatility:                   1%                      319 °C
    TGA (% weight loss)           5%                      353 °C
                                  10%                     370 °C
                                  50%                     414 °C
                                  90%                     436 °C

    Specific gravity:             3.0, 3.25               at 20 °C

    Decabromodiphenyl ether

    Vapour pressure:              <10-6                   20 °C
    (mmHg)                        <1                      250 °C
                                  2.03                    278 °C
                                  5.03                    306 °C

    Solubility:                   water                   20-30 µg/litre
    (at 25 °C)                    cottonseed oil          600 mg/litre
                                  saturated copra oil     920 mg/litre
                                  acetone                 0.5, 1.0 g/litre
                                  benzene                 1.0, 4.8 g/litre
                                  chlorobenzene           6.0 g/litre
                                  methylene bromide       4.2 g/litre
                                  methylene chloride      1.0, 4.9 g/litre
                                   o-xylene                8.7 g/litre
                                  methanol                1 g/litre
                                  toluene                 2 g/litre
                                  methyl ethyl ketone     1 g/litre
                                  pentane                 <1 g/litre
                                  styrene                 <1 g/litre

    Stability:                    stable under normal temperatures and
                                  pressures

    Flash-point:                  none

    Flammability:                 non-flammable

    Autoignition point:           not applicable

     n-Octanol/water
    partition
    coefficient
    (log Pow):                    5.24; 9.97*

        From: Norris et al. (1973, 1974, 1975a,c); Tabor & Bergman (1975);
    US EPA (1986); Chemag. (1988); Great Lakes Chemical Corporation
    (1990b); IARC (1990); Kopp (1990); Watanabe & Tatsukawa (1990)*;
    Bromine Compounds Ltd. (1992); Ethyl Corp. (1992a).

    2.3  Analytical methods

        The detection and quantification of DeBDE have been investigated
    by several authors. The methods are based on gas-liquid
    chromatographic separation using different detection methods, such as
    electron capture detection and mass spectrometry (see General
    Introduction, section 2.1 and Table 2).

    3.  SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE

    3.1  Natural occurrence

        DeBDE has not been reported to occur naturally (see General
    Introduction, section 1.1).

    3.2  Anthropogenic sources

    3.2.1  Production levels and processes

        DeBDE is produced by the bromination of diphenyl oxide in the
    presence of a Friedel-Crafts catalyst (Larsen, 1978). It is
    manufactured in a batch process in enclosed vessels during both the
    reaction and the drying cycle (US EPA, 1988; IARC, 1990).

        Commercial production of DeBDE in the USA began in 1976. Among
    brominated flame retardants, the quantities produced rank second only
    to the quantities of tetrabromobisphenol A. There are 2 manufacturers
    in the USA (BFRIP, 1992). IARC (1990) reported 2 manufacturers in
    Belgium, 1 each in Switzerland, the United Kingdom, and Israel, and 5
    in Japan (US EPA, 1988).

        About 30 000 tonnes of DeBDE are used annually throughout the
    world. About 40% of this total is used (in combination with antimony
    trioxide) in high-impact polystyrene applications, such as television
    and radio cabinets. Textile applications, such as a polyester fibre
    additives and coatings for automobile fabric, tarpaulins, and tents
    account for about 900 tonnes (IARC, 1990; OECD, 1991; Arias, 1992).

        The annual consumption of DeBDE in Japan was 1000 tonnes in 1976,
    2900 tonnes in 1984, 4000 tonnes in 1987, and 9800 tonnes in 1991,
    mainly used for polystyrene, polyester, and polypropylene (Watanabe,
    1987; Watanabe et al., 1987b; Watanabe et al., undated). Recently
    published figures from a Japanese study showed that the consumption of
    PBDE (mainly DeBDE) in Japan was about 20-30% of the total consumption
    of brominated flame retardants (OECD, 1991).

        In the Federal Republic of Germany, 1800-2000 tonnes were used in
    plastics in 1988. DeBDE mixed with antimony trioxide and DeBDE used in
    conjunction with tetrakis (hydroxymethyl) phosphonium (THP) salt
    finishes and an acrylic binder are used to blend 50/50 and 65/35 with
    polyester/cotton (Ulsamer et al., 1980).

        An estimation of the use of decabromodiphenyl ether in the
    Netherlands in 1988 was 1100-1300 tonnes (Anon, 1989).

    3.2.2  Uses

        DeBDE is a non-reactive, additive flame retardant widely used for
    its high bromine content, thermal stability, and cost effectiveness.
    It is used in thermoplastic resins, thermoset resins, textiles,
    adhesives, and coatings. The major applications are for high-impact
    polystyrene, cross-linked polyethylene polybutyl-eneterephthalate,
    glass-reinforced thermoset and thermoplastic polyester moulding
    resins, low density polyethylene extrusion coatings, non-drip
    polypropylene (homo and copolymers), acrylo-nitrile-butadiene-styrene
    rubber (ABS), nylon, adhesives, epoxy resins, polyvinylchloride, and
    elastomers. The concentrations of DeBDE in the polymers range from 6
    to 22% (Tabor & Bergman, 1975; Flick, 1986; NTP, 1986; Kaart & Kokk,
    1987; IARC 1990).

        A mixture of DeBDE and antimony trioxide has been used to treat
    nylon and polyester/cotton fabrics for industrial safety apparel and
    tents (LeBlanc, 1979). DeBDE is also used in the insulating materials
    for wire and electrical cable (IARC, 1990).

        In the United Kingdom, approximately 1000-1200 tonnes DeBDE is
    used per year in the textile industry (back coatings on synthetic
    fibres) (United Kingdom Department of Environment, 1992).

    4.  ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION

    4.1  Transport and distribution between media

    4.1.1  Extraction from polymers

        Pellets of ABS (acrylonitrile-butadiene-styrene) terpolymer and
    polystyrene containing 10% DeBDE, were placed in 2 litres of water and
    shaken mechanically. Total bromine in water was estimated after 3 h
    and up to 187 h. Extraction of bromine took place from the ABS, during
    the first 43 h, in concentrations ranging from <1.0 to 3.7 mg/litre.
    No bromine was extracted from polystyrene (limit of determination
    <0.5 mg/litre). Because there was no increase in bromine
    concentration with time, it was suggested by the authors that the
    levels found were due to erosion and not to extraction. Extraction
    studies were also carried out under static conditions with pellets of
    ABS containing 4.25% DeBDE. Water, acetic acid, and cottonseed oil
    were used as extraction solvents at temperatures of approximately 50
    or 60 °C, during 1 or 7 days. Extraction occurred only with cottonseed
    oil (7 days, 60 °C) at 1 mg DeBDE/litre (limit of determination
    0.075 mg/litre) (Norris et al., 1973, 1974, 1975a).

    4.2  Biotransformation

    No data are available.

    4.3  Abiotic degradation

    4.3.1  Photodegradation

        Studies have been performed on the photodegradation of DeBDE in
    organic solvents and water. Organic solvents were used in the initial
    photodegradation studies because of the extremely low water solubility
    of DeBDE. In xylene, DeBDE was photodegraded by reductive
    debromination with a half-life of 15 h (Norris et al., 1973, 1975a).

        A commercial mixture of DeBDE containing traces of a
    nonabromodiphenyl ether, was irradiated in hexane solution with UVR
    and sunlight. A complicated mixture of tri- to octabromo-diphenyl
    ether congeners was detected. Furthermore, a large number of PBDF
    containing 1-6 bromo atoms was formed. The yield of the PBDF under the
    experimental conditions was approximately 20% of the total amount of
    DeBDE, after 16 h of irradiation by UVR and approximately 10% by
    sunlight. The formation and distribution of photoproducts by sunlight
    were similar to those of UVR, though a few differences could be
    recognized in both, i.e., the decomposition rate of DeBDE and the
    total amount of, and kinds of, PBDF formed. Polybromobenzenes were
    also found in minor quantities in this experiment. The formation of
    PBDF appeared to occur secondarily from debrominated diphenyl ethers
    as photoproducts of DeBDE, but not directly from DeBDE (Watanabe &
    Tatsukawa, 1987).

        The xylene studies showed that DeBDE photodegraded readily, but
    did not provide any indication of the nature of the stability of the
    decomposition products of DeBDE in an aqueous environment. The
    proposed stepwise photoreduction of DeBDE in xylene could lead to the
    formation of lower brominated diphenyl ethers, which might be more
    stable to UVR. However, in water, photohydroxylation would be the
    favoured route and the hydroxyl substituted degradation products would
    decompose rapidly via increased UV absorption. This was demonstrated
    when DeBDE in water was exposed to actual sunlight over a 3-month
    period (10 g DeBDE in 8 litres of water). This study was conducted to
    determine whether stable lower brominated diphenyl ethers were formed
    that would show increased persistence over DeBDE. Analysis (by GC/MS)
    of the exposed water solution after 31, 66, and 98 days showed a
    significant increase in bromine concentration relative to the

    unexposed 98-day sample. After 98 days, the bromine concentration
    corresponded to the breakdown of about 300 times the initial amount of
    DeBDE soluble in water. Xylene extracts of the water phase (if both
    98-day samples were analysed using electron capture gas
    chromatography. Levels of 4-mono-bromodiphenyl ether and
    4,4'-dibromodiphenyl ether were quantified and found to be <5 and
    <2 ppb, respectively. In no case did the exposed sample show an
    increase in any peak, with retention times similar to those of the
    lower brominated diphenyl ethers.

        The products of the photodegradation of DeBDE in water are not
    lower brominated diphenyl ethers (Norris et al., 1973, 1975a).

    4.3.2  Pyrolysis

        A commercial DeBDE, FR 300 BA (77% DeBDE), was heated in a quartz
    tube at 700, 800, and 900 °C and the concentrations of PBDD and PBDF
    determined. The residues contained tetra- to octabromodibenzofurans
    together with hepta- and octabromodioxins; the optimal formation
    temperatures were 800 and 900 °C (Thoma et al., 1987a; Zacharewski et
    al., 1988).

        FR 300 BA (77%) was pyrolysed at 600, 700, 800, and 900 °C in the
    absence of oxygen in a SGE pyrojector and the residues were analysed
    using GC/MS in an on-line operation. Polybromobenzenes (PBB),
    polybromonaphthalenes (PBN), and polybrominated dibenzofurans were
    detected in the pyrolysate. Sixty percent of the starting products
    were decomposed at 600 °C, hexabromobenzene being formed as the main
    component together with traces of pentabromobenzenes and
    nonabromodiphenyl ether. At a higher temperature (700 °C), the
    pentabromobenzene concentration increased and tetrabromobenzenes were
    also formed. Maximum amounts of hepta- and octabromodibenzofurans and
    hexabromonaphthalenes were produced at this temperature. At 800 °C and
    higher, an increase in levels of tetra- and pentabromobenzenes was
    observed. During these reactions, the C-O bond is cleaved followed by
    the attachment of a bromine atom. C-C ring closure leading to
    dibenzofuran formation is very strongly suppressed by DeBDE (Thoma &
    Hutzinger, 1987, 1989).

        In the case of decabromodiphenyl ether (DeBDE), a total amount of
    1-2% PBDF and PBDD was formed on thermolysis of DeBDE. At a
    temperature of 630 °C, 90% of DeBDE was decomposed. The major products
    were PBBz (tri- to hexabrominated). A heptabromodibenzofuran was a
    main product, though tetra- to heptabromodibenzofurans and tetra- to
    octabromodibenzodioxins were also found. In these experiments, PBDF
    and PBDD were formed, which contained at least one or two,
    respectively, bromine substituents less than the PBDE in the technical
    product; often the same major isomers were present (Buser, 1986).

    4.3.3  Combustion of polymers containing DeBDE

    4.3.3.1  Pyrolysis studies

    Clausen et al. (1987), Bieniek et al. (1989), and Lahaniatis (1989)
    studied the influence of the combustion temperature on the formation
    of PBDD and PBDF from plastics containing DeBDE. The results of the
    experiments with PBT with 10% DeBDE/6% Sb2O3 at temperatures of 400,
    500, 600, 700, and 800 °C in the presence of air, showed the formation
    of PBDFs at mg/kg (ppm) concentrations. 2,3,7,8-TeBDD was not found
    with a limit of determination of 10 mg/kg. Maximum formation of TeBDF
    (4000 mg/kg) occurred at 400 °C, and, with increasing temperature,
    concentrations decreased. No PBDF were formed in the thermolysis of
    PBT with DeBDE but without Sb2O3. The results are summarized in
    Table 10.

        Comparable experiments were reported by Lahaniatis et al. (1991).
    The formation of 2,3,7,8-tetrabromodibenzodioxin and -furan from
    various polymers with DeBDE or PBDE were studied in thermolysis
    experiments at 400, 600, and 800 °C. The polymers studied were PBT
    with 10% DeBDE with, or without, 6% Sb2O3, epoxide resin (ER) with
    3-6% DeBDE, and phenol resin (PR) with 3-6% of PBDE and copper. The
    concentrations of the TeBDD and TeBDF at the 3 temperatures are given
    in Table 11. The 2,3,7,8-TeBDD concentrations ranged from 0.01 to
    7 mg/kg and the 2,3,7,8-TeBDF concentrations from 0.01 to 52 mg/kg.
    The concentrations decreased with increasing temperature, and were low
    at 800 °C.

        Pure DeBDE and commercial polybutyleneterephthalate polymer
    samples containing DeBDE and antimony trioxide have been pyrolysed at
    temperatures ranging from 300 to 800 °C. The experiments were carried
    out in a vertical combustion apparatus. The polymer/DeBDE samples
    were: polybutylene-terephthalate (PBT) with 11% DeBDE and 5.5%
    Sb2O3, PBT with 9% DeBDE and 7% Sb2O3, and PBT with 11% DeBDE and
    2.7% Sb2O3 (Dumler et al., 1989a,b). The results of the pyrolysis
    studies are given in Table 12. TeBDF were formed, with yields of up to
    16%, from the 3 polymer samples. PBDF were mainly formed during
    pyrolysis in the presence of DeBDE and Sb2O3. At 300 °C, the
    conversion of DeBDE to PBDF was low, while highly brominated compounds
    were formed. By increasing the temperature, the yield of
    polybrominated compounds increased and more lower brominated PBDF were
    formed. The maximum formation of PBDF occurred between 400 and 500 °C.
    With increasing temperature, not only ring-closure reactions but also
    debromination reactions with the predominant formation of tri- and
    tetra- brominated PBDF may occur, The same reactions probably occur at
    600 °C. At these elevated temperatures, PBDD were also detected to a
    minor extent. The polymers with the lowest amount of Sb2O3 gave the
    lowest PBDF concentrations. With increasing amounts of Sb2O3, the
    concentration of PBDF increased, which suggests that antimony trioxide

    plays a catalytic role. Pure DeBDE, pyrolysed under the same
    conditions, produced significantly lower PBDF concentrations than
    polymers with the flame retardants. In the case of pure DeBDE, the
    temperature for the maximum formation of PBDF shifted to 700 °C.

        Table 10.  Thermolysis products of PBT with 10% decabromodiphenyl ether and 6% Sb2O3a
                                                                                             

                          400°C       500°C        600°C        700°C       800°C
                                                                                             

    Bromodiphenyl ether

    MBDE                   10          50           --           --          --

    DiBDE                  30         100           --           --          --

    TrBDE                 100         200           50           --          --

    TeBDE                 500         300           --           --          --

    PeBDE                 800         400           --           --          --

    HeBDE                1000         400           --           --          --

    HpBDE                 500         400           --           --          --

    OBDE                (500)          --           --           --          --

    Bromodibenzofuran

    MBDF                  100         300          100           50          --

    DiBDF                 500         400          200           10          --

    TrBDF                3000        2000          400           --          --

    TeBDF                4000        3000          600           --          --

    PeBDF                4000        1000          200           --          --

    HxBDF                1000         200           --           --          --

    HpBDF               (500)          --           --           --          --
                                                                                             

    a  From: Clausen et al. (1987); Bieniek at al. (1989).
       Semiquantitative values in mg/kg based on the sample -- not confirmed.
       2,3,7,8-Tetrabromodibenzofuran was not found (limit of determination 20 mg/kg).
       2,3,7,8-Tetrabromodibenzodioxin was not found (limit of determination 10 mg/kg).

    Table 11.  Generation of 2,3,7,8-TeBDD/TeBDF by thermolysis of plastics with flame
               retardants as additives in mg/kga,b
                                                                                             

    Compound                    2,3,7,8-TeBDD                       2,3,7,8-TeBDF
                                                                                             

    Sample               400 °C    600 °C     800 °C        400 °C    600 °C    800 °C
                                                                                             

    PBT/DeBDE/Sb2O3      0.02      0.01        --c          52         5.7        --

    PBT/DeBDE            --c       --c         --c           2.5       4.2      0.08

    Five samples of
    ER/DeBDE
    minimum              0.05      0.3        0.01           0.4       0.6      0.01
    maximum              0.3       0.8        0.03           1.0       2.5      0.04

    PR/DeBDE/Cu          --d       7           --d         --d         5.7       --d
                                                                                             

    a  From: Lahaniatis et al. (1991).
    b  The mg/kg values are based on the material used.
    c  Non-detected, detection limit 0.01 mg/kg.
    d  = Not determined.

    Table 12.  Results of pyrolysis studies

    A.  Polymer Sample A: Polybutyleneterephthalate with 11% decabromodiphenyl ether and 5.5%
        antimony (III) oxide (yields in mg/kg, relative to the flame retardant)a
                                                                                             

              300 °C     400 °C      500 °C       600 °C       700 °C       800 °C
                                                                                             

    MBDF       --          754        3012         5551         3513        3076

    DiBDF       9         2357      10 219       15 343         8445        1547

    TrBDF       9       10 747      37 911       32 751       28 592        1274

    TaBDF       9       14 979      52 634       37 437       35 963        1511

    PeBDF      55         2293      18 391       20 666       13 504         555

    HxBDF     703          127        3713       10 438         2639         109

    HpBDF    1320           --         246          946          491          --

    OBDF       --           --          --           --           --          --
                                                                                             

    B.  Polymer Sample B: Polybutyleneterephthalate with 9% decabromodiphenyl ether and 7%
        antimony (III) oxide (yields in mg/kg, relative to the flame retardant)
                                                                                             

              300 °C     400 °C      500 °C       600 °C       700 °C       800 °C
                                                                                             

    MBDF       --           --      13 088         7633         8510        1144

    DiBDF      --           --      15 754       10 643         9721         244

    TrBDF      47          456      34 408       24 842       19 276          44

    TeBDF    1472         4544      48 762       35 230       23 353         367

    PeBDF    5560       18 132      24 753       16 154         6988         156

    HxBDF    2886        24446      18 587         8832         1633          22

    HpBDF     420         6910        2877          922          100          --

    OBDF       --           --          --           --           --          --
                                                                                             

    a  From: Dumler et al. (1989b).
    Table 12.  (cont'd).

    C.  Polymer Sample C: Polybutyleneterephthalate with 11% decabromodiphenyl ether and 2.7%
        antimony (III) oxide (yields in mg/kg, relative to the flame retardant)
                                                                                             

              300 °C     400 °C      500 °C       600 °C       700 °C       800 °C
                                                                                             

    MBDF       --         2202        3413         2129          610          18

    DiBDF      --         5187        6124         1674           82          --

    TrBDF      --       15 033      15 952         1738           36          15

    TeBDF      --       17 836      17 463          901            9          12

    PeBDF      --         9127        3349           39           --          --

    HxBDF     464         2457         901           82           --          --

    HpBDF    2375         1329         246           36           --          --

    OBDF    traces       traces         --           --           --          --


    D.  Decabromodiphenyl ether (yields in mg/kg)
                                                                                             

              300 °C     400 °C      500 °C       600 °C       700 °C       800 °C
                                                                                             

    MBDF       --           --          --           --           --           2

    DiBDF       4            8          --            3            2           1

    TrBDF       4           13          --            4           25           3

    TeBDF      --           15          11           --          100         102

    PeBDF      --           16         218          380          591         218

    HxBDF      --           42         109           61         1965         988

    HpBDF      --           --        1081         1734         4539         418

    OBDF       --           --          --           --           --          --
                                                                                             

    
        A sample (1 g) of industrial polypropylene containing 125 g
    DeBDE/kg and 75 g Sb2O3/kg, and a pure DeBDE sample, without
    additives, were pyrolysed in a DIN-oven or in a sealed quartz ampoule
    at temperatures of 400, 600, or 800 °C. Combustion products obtained
    with the pyrolysis of pure DeBDE (50 mg) in the DIN-oven were mainly
    hexabromobenzenes and the yields at 400, 600, and 800 °C, were 123,
    568, and 6 g/kg, respectively. PBDF/PBDD were found in concentrations
    of 1, 3, and 2 g/kg at 400, 600, and 800 °C, respectively. At 400 and
    600 °C, HxBDF up to OBDF were found in concentrations of between 96
    and 1449 mg/kg. At 800 °C, lower PBDF, e.g., TrBDF, TeBDF, and PeBDF,
    were also present in concentrations ranging between 11 and 35 mg/kg.
    The concentrations of HxBDF and HpBDF were 81 mg and 959 mg/kg,
    respectively, but no OBDF was found. The concentrations of PBDD at
    400-600 °C for HxBDD up to OBDD were between 6 and 329 mg/kg; at
    800 °C, lower brominated compounds, e.g., TrBDD, TeBDD, and PeBDD were
    also found at concentrations of between 8 and 35 mg/kg. HxBDD up to
    OBDD were present in concentrations of between 74 and 452 mg/kg. The
    combustion products of the samples of polypropylene containing
    DeBDE/Sb2O3 were mainly PBDF and PBDD and the concentrations were
    much higher than from the combustion of the pure DeBDE. MBDF up to
    HpBDF were present at concentrations of between 4762 and
    107 517 mg/kg, 1033 and 49 677 mg/kg, and 353 and 29 147 mg/kg at 400,
    600, and 800 °C, respectively. At all 3 temperatures, TeBDF were found
    in the highest concentrations. The results with polypropylene
    containing DeBDE/Sb2O3, pyrolysed in a sealed quartz ampoule at
    600 °C, showed only MBDF up to PeBDF at concentrations ranging between
    8860 and 142 940 mg/kg. The highest concentrations were found for
    TrBDF and TeBDF. PBDD were not found. From this study, it is clear
    that pure DeBDE gives much lower PBDF values than polypropylene
    containing DeBDE/Sb2O3 (Dumler et al., 1990).

        The formation of PBDD and PBDF during the pyrolysis of PBT
    containing DeBDE was studied at different temperatures and carrier gas
    compositions. PBDF were formed at ppm levels. Even when oxygen was
    available in the carrier gas, PBDD were formed at a much lower level
    than PBDF. In the presence of 10% oxygen, the maximum yield of tetra-
    to octabromodibenzofurans was 70 ppm at 600°C. The yields of
    2,3,7,8-TeBDF and 1,2,3,7,8-PeBDF were less than 4.5 ppm. The thermal
    degradation processes of the polymer were investigated using
    thermogravimetric analysis. The flame retardant did not exert any
    influence on the elementary chemical degradation processes. The flame
    retardant activity of DeBDE consists of the emission of brominated
    species in the gas phase, which scavenge the propagation radicals and
    reduce flammability. The mechanisms of formation of PBDD and PBDF from
    DeBDE in PBT consist of a combination of a condensed phase and a gas
    phase mechanism (Luijk & Govers, 1992).

        Macro-pyrolysis experiments were performed in a quartz tube
    reactor. The polymer sample, PBT, was inserted in the pre-heated tube
    and exposed at 400-700 °C for 20 min. The carrier gas was nitrogen, or
    nitrogen combined with 5% or 10% oxygen. The results are given in
    Tables 13 and 14. PBDF were formed in all tests with the different
    carrier gases, but the yield of PBDD was at least two orders of
    magnitude lower than that of the PBDF. In a nitrogen atmosphere, no
    PBDD were detected (Luijk & Govers, 1992).

        Using GC/MS, Sovocool et al. (1990) analysed pyrolysates of PBT
    resins (flame retarded with DeBDE) which had been exposed to
    temperatures of 400 and 600 °C in the presence of oxygen. They found
    brominated dioxins, brominated dibenzofurans. brominated naphthalenes,
    brominated benzenes and brominated toluenes, brominated biphenyls, and
    brominated methyldibenzofurans (Me-PBDF). Besides the
    methyldibenzofurans, other (C2 and C3) alkyl-PBDF were found in the
    pyrolysates. Numerous congeners of ethyl- (and/or dimethyl)-PBDF and a
    few propyl (and/or trimethyl or ethylmethyl)-PBDF were detected.

        The C2- and C3-alkyl-PBDF found in the pyrolysates exhibited
    relatively intense (M-CH3)+ fragments, supporting the argument for
    ethyl-and propyl or ethyl-methyl substitutions rather than dimethyl
    and trimethyl substitution patterns.

        Early in 1987, the General Electric Company (GE) began to
    investigate the pyrolysis of polybutyleneterephthalate (PBT) flame
    retardant systems. The initial work was carried out at temperatures of
    600-900 °C, but subsequent efforts were at processing temperatures in
    the range of 200-500 °C. The results showed little or no formation of
    PBDD at temperatures of 250-400 °C; concentrations of PBDF in the
    pyrolysed products were as high as about 6000 mg/kg. The
    concentrations of 2,3,7,8-substituted dibenzofurans were much lower,
    not exceeding a maximum of 150 mg/kg. The results for PBDD and PBDF
    were much higher than would be expected, based on the previous work by
    Buser and Hutzinger. The results were also inconsistent with what was
    observed in combustion experiments. The explanation was that the
    exposure times and conditions used did not represent a good model of
    what would actually occur in moulding equipment (BFRIP, 1990).

        In the GE experiments at the Fresenius Institute, an apparatus was
    used in which a small sample of the polymer in the form of a finely
    ground powder was exposed to the pyrolysis temperature in a flowing
    air stream. The pyrolysis time for these samples varied from 10 min at
    the high temperatures to as much as 1.5 h at the low temperatures.
    This is in contrast to extrusion and moulding operations in which the
    polymer is in the form of a molten mass, air is largely excluded, and
    exposure lasts less than 1 min.


        Table 13.  The yield of PBDF during the pyrolysis of PBT/DeBDE in ppm relative to blend, under different carrier gas conditionsa
                                                                                                                                          

    Temperature     TrBDF         TeBDF         2,3,7,8-         PeBDF        1,2,3,7,8-       HxBDF         HpBDF           NBDF
    [°C]                                          TeBDF                          PeBDF
                                                                                                                                          

                                                               Nitrogen
    400           6.7 (0.8)      3.9 (2.4)      0.15 (0.09)    8.7 (0.5)      0.2 (NS)b      10.6 (1.9)     3.7 (0.4)     0.05 (0.00)
    500           15.9 (2.8)     14.5 (0.8)     0.6 (0.1)      13.3 (2.5)     0.1 (NS)b      9.8 (1.1)      4.8 (0.9)     0.1 (0.1)
    600           6.8 (0.4)      4.9 (0.2)      0.2 (0.0)      4.5 (1.8)      0.1 (NS)b      2.9 (0.5)      0.7 (0.2)     NDc
    700           4.2 (0.8)      1.2 (0.1)      0.1 (NS)       0.5 (0.0)      (NS)b          0.2 (0.0)      0.06 (0.02)   NDc

                                                          Nitrogen + 5% oxygen

    400           4.7 (1.4)      3.6 (1.1)      0.2 (0.1)      3.6 (1.1)      0.1 (NS)b      2.9 (1.2)      0.7 (0.3)     NDc
    500           7.7 (0.7)      6.4 (0.4)      0.4 (0.1)      5.3 (0.1)      0.1 (0.0)      5.3 (0.1)      1.1 (0.0)     NDc
    600           22.1 (2.7)     17.2 (1.8)     2.4 (0.3)      17.7 (3.2)     0.8 (0.2)      16.8 (1.3)     4.8 (0.3)     0.3 (0.0)
    700           15.7 (0.3)     7.6 (0.1)      1.2 (0.0)      6.6 (1.2)      0.4 (0.1)      5.7 (0.2)      1.3 (0.3)     0.08 (0.03)

                                                          Nitrogen + 10% oxygen

    400           9.6 (0.7)      7.5 (1.0)      0.3 (0.1)      7.7 (1.5)      (NS)b          5.9 (3.0)      1.8 (1.0)     NDc
    500           11.0 (0.3)     8.7 (0.5)      0.6 (0.1)      8.8 (0.4)      0.2 (0.0)      8.7 (0.8)      3.7 (0.3)     NDc
    600           28.8 (3.2)     20.8 (1.8)     3.4 (0.5)      21.6 (3.4)     1.2 (0.2)      17.8 (1.3)     7.6 (1.1)     0.8 (0.1)
    700           17.5 (0.7)     10.3 (1.4)     2.0 (0.2)      8.9 (0.3)      0.6 (0.0)      5.3 (0.3)      2.1 (0.3)     0.02 (0.02)
                                                                                                                                          

    a  From: Luijk & Govers (1992).
    b  NS = not separable, due to interferences.
    c  ND = not detected (below detection limit).

    Table 14.  The yield of PBDD during the pyrolysis of PBT/DeBDE in ppb relative to blend, under different carrier gas conditionsa
                                                                                                                                     

    Temperature    TrBDD         TeBDD        2,3,7,8      PeBDD     1,2,3,7,8-     HxBDD         HpBDD         NBDD
    [°C]                                       TeBDD                   PeBDD
                                                                                                                                     

                                                  Nitrogen + 5% oxygen

       400          NSb           NSb         NSb          NSb          NSb          NDc           NDc          NDc
       500          NSb           NSb         NSb          NSb          NSb          NSb          7 (2)        4 (4)
       600          NSb         8 (NSb)       NSb        44 (6)         NSb       110 (10)       43 (0)       13 (1)
       700          NSb          5 (1)        NSb        19 (6)         NSb        40 (5)         8 (2)         NDc

                                                  Nitrogen + 10% oxygen

       400          NSb           NSb         NSb          NSb          NSb          NDc           NDc          NDc
       500        6 (NSb)         NSb         NSb        3 (NSb)        NSb       48 (NSb)      16 (NSb)        NDc
       600       44 (NSb)       29 (7)        NSb       75 (NSb)        NSb       106 (11)       46 (4)       16 (0)
       700        32 (18)      24 (NSb)       NSb       21 (NSb)        NSb        19 (3)         4 (4)         NDc
                                                                                                                                     

    a  From: Luijk & Govers (1992).
    b  NS = Not separable, due to interferences.
    c  ND = Not detected (below detection limit).

    

        Dumler et al. (1989b) have recently published data from studies on
    the pyrolysis of PBT/DeBDE resins. This work was conducted in
    apparatus identical to that used by GE, thus, the results can be
    compared. In the report by Hutzinger and coworkers, concentrations of
    PBDF were calculated relative to the flame retardant only.
    Recalculation of the results by BFRIP (1990), on the basis of the
    total polymer, showed general agreement with the GE results
    (Table 15).

        Hutzinger's recent work was summarized in a report by Pohle of the
    Umwelbundesamt (Umweltbundesamt, 1989). In this work, the tube furnace
    (DIN Apparatus) and the vertical quartz oven (VCI Apparatus; as used
    by the Fresenius Institute) were used to pyrolyse polymers containing
    PBDE at temperatures ranging from 600 to 750 °C. The results showed
    that PBDF were formed under these conditions, but that 2,3,7,8-TeBDF
    was only a small fraction of the total. In general, the results were
    similar to those reported earlier by Hutzinger and GE.

        Because of the lack of good data collected under actual operating
    conditions, BFRIP met with 6 major polymer producers in 1988, to
    design a series of experiments to investigate the behaviour of DeBDE
    and OBDE in HIPS, ABS, and PBT under controlled moulding or extrusion
    conditions. The experiments are outlined in Tables 16 and 25 (in OBDE
    section 4.2.3). For the three polymer systems, HIPS/DeBDE, ABS/OBDE,
    and PBT/ DeBDE, samples were moulded in the application laboratories
    of polymer producers. For the moulding operations, the severity of
    operations ranged from normal to extreme. Normal conditions were those
    in the middle range recommended by the resin manufacturers for
    processing. The abusive conditions were at, or slightly above, the
    maximum recommended exposure time and temperature. The extreme
    conditions were well above those recommended by the resin manufacturer
    and resulted in samples with severely degraded physical properties
    and/or colour.

        After moulding, all the samples were analysed by Triangle
    Laboratories, Research Triangle Park, NC (TLI). Samples were also sent
    to the US EPA Laboratory in Las Vegas for confirming analyses. The
    results of these analyses are summarized in Tables 17 and 26 (in OBDE
    section 4.2.3) and are discussed more fully in the report of this
    study made at Dioxin'90 (McAllister et al., 1990; BFRIP, 1990). With
    the exception of a single sample, PBDD were not identified in any of
    the samples and 2,3,7,8-TeBDF were seen only in this one sample at
    very low concentrations. In general, the Triangle Park and US EPA
    results agreed fairly well for the TBDF and TBDD.


        Table 15.  Comparison of GE and Hutzinger results on pyrolysis of PBT/DeBDE Resin (PBT/11% DeBDE/2.7% antimony trioxide)
               All concentrations in mg/kg relative to total polymera
                                                                                                                                                

                        300 °C              400 °C                500 °C                600 °C               700 °C                800 °C
                                                                                                                                                

    Compound      General    Dumler   General     Dumler    General     Dumler    General    Dumler    General     Dumler    General     Dumler
                  Electric   et al.   Electric    et al.    Electric    et al.    Electric   et al.    Electric    et al     Electric    et al.
                  USA        (1989)   USA         (1989)    USA         (1989)    USA        (1989)    USA         (1989)    USA         (1989)
                                                                                                                                                

    MBDF          NAb        -                     240                   370                  230                    70                  NDc
    DiBDF         -          -                     570                   673                  180                     9                  -
    TrBDF         -          -                    1650                  1750                  190                    36                  NDc
    TeBDF         5200       -         2000       1960      1200        1920       490        100      24             4      0.03        NAb
    2,3,7,8-      150        -           64          -       120           -        19          -      0.4            -      0.005       -
    TeBDF
    PeBDF         5900       -         1200       1003      1300         370       350         40      8              -      0.006
    1,2,3,7,8-    NDc        -          NDc          -       NDc           -       NDc          -      NDc            -      NDc         -
    PeBDF
    HpBDF         NDc        260        NDc        150        50          40         3          4      0.1            -      NDc         -
    OBDF          -          Tr           -         Tr         -         NDc         -        NDc      -              -      -           -
    Total         13 450     310       4100       3383      3220        2430       943        234      35             4      0.04        NAb
    TeBDF-
    HpBDF
                                                                                                                                                

    a  From: BFRIP (1990).
    b  NA = not analysed.
    c  ND = not detected.

    

    Table 16.  Moulding studies with two polymer/FR systems at
               different processing temperaturesa
                                                                    

    Polymer/FRb       Severity       Conditions
                                                                    

    HIPS/DeBDE        None           Base resin, not moulded
                      Normal         215-220 °C, 30- second cycle
                      Abusive        235-245 °C, 5-min cycle
                      Extreme        265-270 °C, 7-min cycle

    PBT/DeBDE         Normal         255 °C, 23-second cycle
                      Abusive        255 °C, 5-min cycle
                      Extreme        255 °C, 10-min cycle
                                                                    

    a  From: McAllister et al. (1990).
    b  HIPS/DeBDE   High impact polystyrene/      84.3%
                       DeBDE +                    12.0%
                       antimony trioxide           3.7%
       PBT/DeBDE    Polybutyleneterepthalate/     88.0%
                       DeBDE +                     6.5%
                       antimony trioxide           5.5%

        Different interpretations of the analytical results of the 2
    laboratories resulted in larger differences in values for hexa-through
    octa-brominated furans. These data showed that the processing of the
    resin systems under normal conditions did not change the composition
    compared with that of the base resin formulation. Even under abusive
    conditions, there was little generation of PBDF or PBDD. In fact, PBDD
    were observed in only 2 of the samples under abusive or extreme
    exposures. 2,3,7,8-Substituted dibenzofurans were not observed, except
    in one sample in which very low ppb levels were seen (Tables 17 and 26
    in OBDE section 4.2.3).

    4.3.3.2  Workplace exposure studies

        The occurrence of PBDF and PBDD during the thermal processing of
    glass-filled PBT resin containing DeBDE at 70 g/kg and Sb2O3 at
    62 g/kg or no flame retardant was studied. No PBDD (limit of
    determination 2 ng) were found. PBDF were present and isomers
    containing bromine at the 2,3,7,8-position represented less than 10%
    of the total PBDF. Fumes evolved during thermal processing of the
    resins were collected at the die-head during extrusion.


        Table 17.  Comparison of Triangle Laboratories Inc. (TLI) (Research Triangle Park) and US EPA Laboratory (Las Vegas) results
               on moulded polymer samples containing various flame retardants. (All concentrations are in mg/kg)a
                                                                                                                                

    High impact polystyrene with decabromodiphenyl ether
                                                                                                                                

                   Base resin 1222-16-0       Normal 1222-16-1             Abusive 1222-16-2          Extreme 1222-16-3
                                                                                                                                

    Compound       TLI        US EPA          TLI         US EPAc          TLI         US EPAd        TLI         EPA
                                                                                                                                

    Total TBDF     0.01       ND               0.01                         0.01       0.002            0.02      ND

    PeBDF          0.04        0.004           0.05                         0.06       0.02             0.2       0.009

    HxBDF          < 5.3       0.95         < 14.3                        < 5.5        0.11          < 34.1       0.2

    HpBDFb         < 0.6       0.72          < 3.5                        < 2.1        0.08          < 10.6       2.1

    PBDFb          < 4.1       0.15          < 9.3                        < 7.0        ND            < 35.7       3.2
                                                                                                                                

    Table 17.  (cont'd).
                                                                                                                                

    PBT with decabromodiphenyl ether
                                                                                                                                

                   Base resin                 Normal 1222-16-6             Abusive 1222-16-7          Extreme 1222-16-8
                                                                                                                                

    Compound       TLI        US EPA          TLI         US EPAd          TLI         US EPA         TLI         US EPAe
                                                                                                                                

    Total TeBDD              < 0.001         < 0.0002    < 0.002            0.001

    Total PeBDD              < 0.001         < 0.0002    < 0.013            0.006

    Total TeBDF                0.003           0.003       0.007            0.03       0.2              1.0

    Total PeBDF                0.02            0.002       0.09           > 7.8        > 25          > 54

    Total HxBDF                0.11            0.013       1.1           > 16.1        > 120          > 7.0

    Total HpBDFb               0.31          < 4.3         3.0            < 4.6       58.5            < 12.1

    Total OBDFb                0.95         < 16.9         3.2            < 9.9        7.5            < 68.8
                                                                                                                                

    aFrom:  BFRIP (1990). Values preceeded by < are maximum possible. Analytical signals met identification criteria, but
            may include contribution from interferences. US EPA and TLI used different identification criteria, resulting in
            differences in reported values.
    b  Concentrations of HpBDF and OBDF from TLI are not validated because of lack of standards.
       Concentrations are reported for comparison only.
    c  Sample 1222-16-1 was spilled during workup.
    d  Average of 2 analyses of same sample.
    e  US EPA results not validated.

    

        The temperature in the 4 temperature zones was between 216 and
    250 °C. It was found that thermal processing of resin with
    DeBDE/Sb2O3 yielded higher concentrations of PBDF in the fumes than
    that of resin without the flame retardants. The concentrations found
    in two samples of resin with flame retardant and one sample without
    flame retardant are given in Table 18.

        In addition to these pyrolysis and moulding experiments, studies
    have been performed to determine the possibility of the workplace
    exposure to PBDF and PBDD of workers in extrusion or moulding
    facilities. The first of these studies was a simulation sponsored by
    General Electric (GE) at Battelle Laboratories in Columbus, OH (BFRIP,
    1990). For this work, an experimental extrusion apparatus was used in
    which the total volatiles from the extruder could be collected and
    analysed. A typical commercial PBT/DeBDE resin was extruded, the
    volatiles were collected and analysed at the Fresenius Institute. The
    results of the analysis were used to estimate a probable workplace
    concentration of 0.76 ng/m3 as TCDD equivalents.

        The following experiment was carried out to determine the risks to
    employees working in the actual production of PBT resin, flame
    retarded with DeBDE, at Hoechst Celanese facility at Bishop, Texas
    (Hoechst Celanese Corp., 1988). High-volume samples were taken above
    the extruder die-head, the extruder vent port, the fibreglass addition
    port, and the raw material feeder, because these were the areas where
    off-gassing was most likely to occur and where employees could be
    exposed to the off-gases from extrusion. Source samples can be
    considered as worst-case situations, as samplers were placed directly
    in the off-gas streams. A fifth sample was taken in an unused guard
    house, 90 m from the extruder building, as a field control. Full-shift
    personal samples were taken on all operators and helpers on each shift
    to determine the actual employee exposure. Each sampler was worn by
    employees for the entire 24-h period. The operating temperature was
    240-260 °C. Personal samples are regarded as more representative than
    the area/source samples, since they were worn by employees during the
    production run.

        Table 18.  Concentrations of PBDF in resins in ng per sample componenta
                                                                                   

    Substance          Two samples with flame retardant      One sample without
                                                             flame retardant
                                                                                   

    TeBDF                  201             1310                     76
    2,3,7,8-TeBDF          15               114                      6
    PeBDF                  131              820                     43
    1,2,3,7,8-          ND (< 2)         ND (< 5)                ND (< 2)
    PeDBF
    HxBDF                  80               425                     23
    1,2,3,4,7,8-
    HxBDF                  < 6              49                       2
    HpBDF                 < 11              51                       2
    Total PBDF             433             2606                     144
                                                                                   

    aFrom:  (Vinci & Craig, 1988).
    The values are the total quantity of PBDF (in ng) found in the 2 sample
    components, while the values of the specific isomers are given as values
    present in the total PBDF. For example: 15 ng of 2,3,7,8-TeBDF present in
    201 ng total PBDF.
    No PBDD was detected in any of these samples (limit of determination, 2 ng).
    bND = not detected.

    
        The concentrations (expressed as TCDD equivalents) in ng/m3 in
    the different air samples were:

              Fibreglass port                    0.027
              Extruder die-head                  3.589
              Extruder vent port                 0.191
              Raw material feeder                0.015
              Guard house                        0.0004
              Personal (three) samples           0.019, 0.011,
                                                 0.122.

        BFRIP sponsored a study at a commercial PBT extrusion facility in
    1988. This study was designed and conducted with input from the
    National Institute of Occupational Safety and Health (NIOSH) and the
    US EPA. In this study, both area samples and personnel monitors were
    used to collect information on potential exposures. Area samples were
    collected from locations expected to show maximum levels of volatile
    components. Personnel samples were collected with pumps worn by
    workers, and represented the average levels to which workers were
    exposed. In all cases, exposures were calculated in terms of TeCDD

    equivalents, using the concept of "Toxicity Equivalent Factors" (TEF)
    (the concentration of a particular chlorinated (brominated)
    dibenzodioxin or dibenzofuran is converted to an equivalent
    concentration of 2,3,7,8-TeCDD by multiplying by the appropriate
    factor). It should be noted that this conversion of exposure values
    for PBDF to TeCDD toxicity equivalents is only an estimate and is by
    no means generally accepted. The results from the area samples are
    summarized in Table 19 and from personnel samples in Table 20. The
    maximum worker exposure for PBDF was 0.1 ng/m3, expressed as TeCDD
    toxicity equivalents (BFR/CEM Working Group, 1989; BFRIP, 1990;
    EBFRIP, 1990).

        Determination of the occupational exposure during extrusion of PBT
    containing DeBDE at 90 g/kg and antimony trioxide at 80 mg/kg, was
    carried out by BASF, in Germany. In air, the total PBDF concentration
    close to the extruder head was 72.9 µg/m3 and that in the rooms
    ranged from 0.169-0.989 µg/m3. Concentrations of hexabromo- and
    heptabromodibenzofurans were the highest, followed by penta- and
    octabromodibenzofuran. The total PBDD concentration in the room was
    28.12 ng/m3, being mainly octa- and hexabromodibenzodioxins. The
    tetrabromodibenzodioxin concentration was 2.04 ng/m3 (Kraus, 1990).

        Umweltbundesamt (1989) reported the results from the workplace
    study conducted by BASF in a PBT extrusion facility. The results from
    the BASF study are summarized in Table 21. The higher level observed
    in the vicinity of the extruder head was removed from the workplace by
    local ventilation. According to the BASF report, workers spent most of
    their time in the "Production room" or at the "Bagging station". Only
    if there were problems with the equipment did they work near the
    extruder. The actual worker exposure would be approximately the levels
    observed in the production room or at the bagging station.

        The results of the BASF and BFRIP studies are summarized in
    Table 22. With the exception of the BASF sample collected at the
    extruder head, the results are generally consistent between the two
    studies. The higher value for this sample, compared with that from the
    extruder die-head from the BFRIP, could be a result of a difference in
    the placement of the sampler (BFRIP, 1990).


        Table 19.  Results from BFRIP air sampling testsa
                                                                                                                                                

    Compound            Toxicity                                                       Area Samples                                             
                        equivalent  Fibreglass port          Extruder die head      Extruder vent port   Feed hopper           Guard gate
                        factor                                                                                                                  
                                    CONCb   TCDD             CONCb   TCDD           CONCb   TCDD         CONCb    TCDD         CONCb    TCDD
                                            equivalentc              equivalentc            equivalentc           equivalentc           equiv.c
                                                                                                                                                

    2,3,7,8-TeBDD       1.00000     0.0001    0.0001         0.0033    0.0033       0.0016  0.0016       0.0000   0.0000       0.0001   0.0001
    1,2,3,7,8-PeBDD     0.50000     0.0001    0.0000         0.0059    0.0030        0.003  0.0016       0.0006   0.0003       0.0001   0.0001
    1,2,3,4,7,8-HxBDD   0.10000     0.0002    0.0000         0.6220    0.0622        0.202  0.0202       0.0002   0.0000       0.0006   0.0001
    1,2,3,6,7,8-HxBDD   0.10000     0.0002    0.0000         0.6221    0.0622        0.202  0.0202       0.0002   0.0000       0.0006   0.0001
    OBDD                0.00100     0.0006    0.0000         0.0382    0.0000        0.020  0.0000       0.0009   0.0000       0.0023   0.0000

    2,3,7,8-TeBDF       0.10000     0.0118    0.0012         0.0017    0.0002        0.104  0.0104       0.0055   0.0005       0.0001   0.0000
    1,2,3,7,8-PeBDF     0.05000     0.0154    0.0008         0.0072    0.0004        0.005  0.0005       0.0092   0.0005       0.0002   0.0000
    1,2,3,4,7,8-HxBDF   0.10000     1.0770    0.1077       126.8512   12.6851        1.962  0.1962       0.6036   0.0604       0.0006   0.0001
    Total TeBDD         0.00000     0.0356    0.0000         1.9360    0.0000        2.199  0.0000       0.0412   0.0000       0.0001   0.0000

    Total PeBDD         0.00000     0.0067    0.0000         0.3079    0.0000        0.003  0.0000       0.0048   0.0000       0.0001   0.0000
    Total HxBDD         0.00000     0.0073    0.0000        36.9172    0.0000        0.448  0.0000       0.0084   0.0000       0.0006   0.0000
    Total TeBDF         0.00000     3.4764    0.0000       394.2480    0.0000       13.735  0.0000       1.4432   0.0000       0.0620   0.0000
    Total PeDBF         0.00000     7.4785    0.0000      1412.8761    0.0000       55.384  0.0000       3.5971   0.0000       0.0000   0.0000
    Total HxBDF         0.00000     2.6888    0.0000      4544.6098    0.0000      146.321  0.0000       0.5275   0.0000       0.0000   0.0000

    Air concentration                         0.1098                  12.8163               0.2503                0.0618                0.0004
    ng/m3
                                                                                                                                                

    a  From: EBFRIP (1990).
    b  All concentrations are expressed as ng/m3.
    c  Toxicity equivalent factors are the international values adopted by the US EPA in 1989.

    Table 20.  Results from BFRIP air sampling testsa
                                                                                                                

    Compound            Toxicity      Personnel monitors
                        equivalent                                                                              
                                           6559                      12524                      49834
                        factor                                                                                  

                                      CONCc       TCDD         CONCb          TCDD          CONCb        TCDD
                                               equivalentc                 equivalentc                equivalentc
                                                                                                                

    2,3,7,8-TeBDD       1.00000       0.0000     0.0000        0.0000        0.0000         0.0000      0.0000
    1,2,3,7,8-PeBDD     0.50000       0.0000     0.0000        0.0005        0.0002         0.0000      0.0000
    1,2,3,4,7,8-HxBDD   0.10000       0.0000     0.0000        0.0025        0.0002         0.0000      0.0000
    1,2,3,6,7,8-HxBDD   0.10000       0.0000     0.0000        0.0025        0.0002         0.0000      0.0000
    OBDD                0.00100       0.0000     0.0000        0.0093        0.0000         0.0000      0.0000

    2,3,7,8-TeBDF       0.10000       0.0132     0.0013        0.0000        0.0000         0.0000      0.0000
    1,2,3,7,8-PeBDF     0.05000       0.0365     0.0018        0.0012        0.0001         0.1855      0.0093
    1,2,3,4,7,8-HxBDF   0.10000       0.3543     0.0354        0.1405        0.0140         5.4102      0.5410

    Total TeBDD         0.00000       0.0000     0.0000        0.0000        0.0000         0.0000      0.0000
    Total PeBDD         0.00000       0.0000     0.0000        0.0005        0.0000         0.0000      0.0000
    Total HxBDD         0.00000       0.0000     0.0000        0.0025        0.0000         0,0000      0.0000

    Total TeBDF         0.00000       1.4065     0.0000        1.1929        0.0000         7.6914      0.0000
    Total PeDBF         0.00000       5.0801     0.0000        5.9643        0.0000        38.8162      0.0000
    Total HxBDF         0.00000       6.5995     0.0000       61.9528        0.0000        70.1965      0.0000

    Air concentration                            0.0386                      0.0149                     0.5503
    ng/m3
                                                                                                                

    a  From: EBFRIP (1990).
    b  All concentrations are expressed as ng/m3.
    c  Toxicity equivalent factors are the international values adopted by the US EPA in 1989.

    Table 21.  Results from BASF air sampling tests
                                                                                                                                         

    Compound            Toxicity                                        Extruder
                        equivalent                                                                                                       
                        factor        Production room       Work station               Bagging station         Extruder head                    
                                                                                                                                         
                                      CONCb      TCDD       CONCb        TCDD          CONCc      TCDD         CONCb        TCDD
                                              equivalentc             equivalentc              equivalentc               equivalentc
                                                                                                                                         

    2,3,7,B-TeBDD        1.00000      0.0       0.0000      0.0         0.0000         0.0       0.0000          0.0       0.0000
    1,2,3,7,8-PeBDD      0.50000      0.0       0.0000      0.0         0.0000         0.0       0.0000          0.0       0.0000
    1,2,3,4,7,8-HxBDD    0.10000      0.0       0.0000      0.0         0.0000         0.0       0.0000          0.0       0.0000
    1,2,3,6,7,8-HxBDD    0.10000      0.0       0.0000      0.0         0.0000         0.0       0.0000          0.0       0.0000
    OBDD                 0.00100      0.0       0.0000      0.0         0.0000         0.0       0.0000          0.0       0.0000

    2,3,7,8 TeBDF        0.10000      0.0       0.0000      0.0         0.0000         0.0       0.0000                    0.0000
    1,2,3,7,8-PeBDF      0.05000      0.0       0.0000      1.3         0.0650         0.0       0.0000         87.0       4.3500
    1,2,3,4,7,8-HxBDF    0.10000      0.0       0.0000      2.6         0.2600         0.3       0.0300       1186.0     118.6000
    Total TeBDD          0.00000      0.0       0.0000      0.0         0.0000         0.0       0.0000          0.0       0.0000
    Total PeBDD          0.00000      0.0       0.0000      0.0         0.0000         0.0       0.0000          0.0       0.0000
                                                                                                                                         

    Table 21.  (cont'd).
                                                                                                                                         

    Compound            Toxicity                                        Extruder
                        equivalent                                                                                                       
                        factor        Production room       Work station               Bagging station         Extruder head                    
                                                                                                                                         
                                      CONCb      TCDD       CONCb        TCDD          CONCc      TCDD         CONCb        TCDD
                                              equivalentc             equivalentc              equivalentc               equivalentc
                                                                                                                                         

    Total HxBDD          0.00000      0.0       0.0000      0.0         0.0000         0.0       0.0000          0.0       0.0000
    Total DiBDF          0.00000      1.1       0.0000      1.3         0.0000         0.2       0.0000        322.0       0.0000
    Total TriBDF         0.00000      13.0      0.0000      7.4         0.0000         1.1       0.0000        705.0       0.0000
    Total TeBDF          0.00000      20.0      0.0000      33.7        0.0000         5.1       0.0000        980.0       0.0000
    Total PeBDF          0.00000      98.0      0.0000      7143.0      0.0000         8.6       0.0000       3910.0       0.0000
    Total HxBDF          0.00000      594.0     0.0000      554.0       0.0000         13.0      0.0000     22 162.0       0.0000
    Total HpBDF          0.00000      260.0     0.0000      200.0       0.0000         88.0      0.0000     39 550.0       0.0000
    Total OBDF           0.00100      0.0       0.0000      0.0         0.0000         7.0       0.0070       5275.0       5.2750

    Air concentration                           0.0000                  0.3250                   0.0370                  128.2250
    ng/m3
                                                                                                                                         

    a  From: EBFRIP (1990).
    b  All concentrations are expressed as ng/m3.
    c  Toxicity equivalent factors are the international values adopted by the US EPA in 1989.

    

        An occupational exposure limit has not been established for any
    PBDD or PBDF, but a recent paper by Leung et al. (1988) provides
    guidance. Applying a 100-fold safety factor to the no-observed-effect
    level in animal studies, an occupational exposure limit of 0.2 ng/m3
    is obtained. For other compounds that behave similarly to TeCDD in
    animals tests, safety factors from 2 to 10 have been used to establish
    the occupational exposure limit. Using a safety factor of 10, the
    occupational exposure limit for TeCDD becomes 2 ng/m3. With the
    exception of the two samples from the extruder die-heads, all of the
    values from the BASF and BFRIP studies were below 2 ng/m3. The
    studies also indicate that workers are unlikely to be routinely
    exposed to levels higher than 0.2 ng/m3.

        BASF has submitted to the US EPA a report of the biological
    monitoring of 5 workers, who were employed in the extrusion of PBT
    containing DeBDE as a flame retardant (BFRIP, 1990). The results
    indicated blood concentrations of 2,3,7,8-TeBDF and 2,3,7,8-TeBDD of
    100-500 ng/litre. All workers appeared in good health. The finding of
    2,3,7,8-TeBDD in the workers was particularly surprising, since air
    samples had not revealed the presence of brominated dioxins. These
    findings have not yet been confirmed, but a follow-up study is in
    progress.

    Table 22.  Summary of BASF and BFRIP air sampling testsa
                                                                    

    Location                      Study      Concentration (ng/m3
                                             air) TCDD equivalent
                                                                    

    Personnel-1                   BFRIP             0.039
    Personnel-2                   BFRIP             0.015
    Personnel-3                   BFRIP             0.550
    Room air                      BASF              0.000
    Work station                  BASF              0.325
    Bagging station               BASF              0.037
    Extruder head                 BASF            128.225
    Fibre glass addition port     BFRIP             0.110
    Extruder die head             BFRIP            12.816
    Extruder vent port            BFRIP             0.250
    Feed hopper                   BFRIP             0.062
    Guard gate                    BFRIP             0.000
                                                                    

    aFrom:  EBFRIP (1990).

        Investigations by plastic producers have shown that PBDF and PBDD
    can be formed, not only on combustion of plastics containing PBDE, but
    also during the blending of the flame retardant into a polymer. This
    has been substantiated by BASF, who measured the workplace atmosphere
    around extruders.

    4.4  Ultimate fate following use

    4.4.1  General

        For the ultimate fate of DeBDE following use, and its effects on
    the environment, see section 6.1. of the General Introduction.

    4.4.2  Exposure of the general population

        No data are available concerning the direct exposure of the
    general population to DeBDE.

        In a study by Ranken et al. (1990) to investigate the possibility
    of exposure to PBDD/PBDF from TV sets, three new TV sets were placed
    in an 8.81 m3 test chamber. Sets A and B were purchased locally,
    while set C was provided by the manufacturer. The rear portion of each
    television set cabinet was constructed from polystyrene. The purchased
    televisions were flame retarded with 11.5% DeBDE. Set C was made of
    high-impact polystyrene, flame retarded with DeBDE/Sb203. In order
    to determine background levels of PBDD/PBDF, air was pulled through
    the empty chamber and through a sampler for 8 h/day, for 3 days. Two
    purchased sets were placed in the chamber. Air was pulled through the
    chamber for 8 h/day, for 3 days. The experiment was repeated for
    another 3 days. The television set (C) was placed in the room for 3
    days, but the television was not in operation. In all the described
    experiments, no PBDD/PBDF were found. Finally, the air was monitored
    for 24 h while the television set C was operating. No PBDD/PBDF were
    found. On the basis of the limits of determination, PBDD/PBDF
    emissions from the operating television sets can be calculated to be
    less than 0.17-1.52 pg TeBDD/m3, 0.35-0.39 pg PeBDD/m3, 0.09-0.33 pg
    TeBDF/m3, and 0.14-0.19 pg PeBDF/m3 of air. The authors concluded
    that, in actual practice, these values would be lower by a factor of
    10-100 because of the dilution effect of a normal room size and the
    expected air turnover.

    4.5  Fire accident

        Bruckmann et al. (1989) reported about an accidental fire in a
    stock-house in which, according to an inventory file, 2.5 tonnes of
    flame retardants (a mixture of DeBDE and antimony trioxide (Traflam
    PO 80)) was stored. Four wipe samples and 6 solid samples of partly
    burnt material were taken several hours after the fire. At the time of
    sampling, it was discovered that only a minor quantity of the bags
    with the flame retardant had been in contact with the fire. The 4 wipe
    samples contained tetra-, penta-, hexa-, hepta-, and

    octabromodibenzofurans in the following concentrations; 4.0-123,
    0.82-77.6, 4.5-51.7, 0.25-12.8, and 0.53-8.5 ng/m2. PBDD were not
    found (limit of determination 1 ng/m2 per isomer). The PBDF contents
    of the solid samples were low with the highest concentration at
    1 µg/kg.

    4.6  Simulated fire conditions

        In the experiments conducted by the BFRIP, samples of high-impact
    polystyrene (HIPS) and HIPS/DeBDE/Sb203 were burned in a Mass Burning
    Rate Apparatus with 21% oxygen to simulate a real fire scenario. The
    temperatures ranged from 500 to 800 °C. Soot and char were collected
    and analysed for PBDD and PBDF (Table 23).

    Table 23.  Analytical results from combustion products of
               HIPS/DeBDEa
                                                                         

    Compound                             Concentration

                                     Char                Soot
                                    (mg/kg)             (mg/kg)
                                                                         

    Brominated dibenzodioxins         NDb                NDb

    Brominated dibenzofurans:

    MBDF                             0.64                556

    DiBDF                            0.54                641

    TrBDF                            0.23                352

    TeBDF                           < 0.1                73

    2,3,7,8-TeBDF                   < 0.1                1.8

    PeBDF                           < 0.1                3.5

    HxBDF-OBDF                      < 0.1               < 0.1
                                                                         

    aFrom:  McAllister et al. (1990); Pinkerton et al. (1989).
    bND = Not detected.


    A single study on a mixed range of PBDE, between HxBDE and
    DeBDE, indicated little bioconcentration in carp with a
    bioconcentration factor of < 4 after 8 weeks of exposure (CBC, 1982).

        No PBDD or PBDF were found in the HIPS without flame retardant.
    Low levels of bromodibenzofurans were found in the char of the
    flame-retarded HIPS, however, the levels of brominated furans ranged
    from 3.5 mg penta- to 641 mg dibromodibenzofurans/kg. No PBDD were
    found in char and soot. A maximum of 1.8 mg/kg of 2,3,7,8-TeBDF was
    present in soot (Pinkerton et al., 1989; McAllister et al., 1990).

    4.7  Bioaccumulation

        A bioconcentration study was carried out with rainbow trout under
    static conditions. The concentration in the water was 20 µg
    14C-DeBDE/litre. Fish were exposed for 0, 1/2, 1, 2, 4, 6, 12, 24, or
    48 h. There was no measurable accumulation of DeBDE in flesh, skin, or
    viscera (Brosier et al., 1972; Norris et al., 1973, 1974, 1975a).

        A single study on mixed PBDE between HxBDE and DeBDE indicated
    little bioconcentration in carp with a bioconcentration factor of <4
    after 8 weeks of exposure (CBC, 1982).

    5.  ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE

    5.1  Environmental levels

    5.1.1  Air

        Decabromodiphenyl ether was identified in 10 samples of air
    collected in the vicinity of two manufacturing facilities in
    concentrations ranging from 0.016 to 25 µg/m3. The compound was
    present in air in the form of particulates (Zweidinger et al., 1977).

    5.1.2  Water

        DeBDE was determined in 15 water samples collected in Japan in
    1977. DeBDE was not present in any of the samples (limit of
    determination 0.2-2.5 µg/litre) (Environment Agency Japan, 1983).
    DeBDE was not detected in 75 water samples (limit of determination
    0.1 µg/litre) in 1987 and was not detected in 141 samples collected at
    47 locations (limit of determination 0.06 µg/litre) in 1988-89 in
    Japan (Environment Agency Japan, 1989, 1991).

        Yamamoto et al. (1991) analysed water from the Kino River basin
    for the presence of DeBDE. In 12 samples of river water, the
    concentrations of DeBDE were all below 0.1 µg/litre water.

    5.1.3  Aquatic sediments

        DeBDE was determined in 15 sediment samples collected in Japan in
    1977. DeBDE was not found in any of the samples (limit of
    determination 25-870 µg/kg dry weight) (Environment Agency Japan,
    1983).

        Marine, estuarine, and river sediment samples were collected at
    different places in Japan in the years 1981-83 and analysed for DeBDE.
    The DeBDE occurred in 6 river and 1 estuarine sediment sample (7 out
    of 15 samples) in the range of 20-375 µg/kg, during this period
    (Watanabe et al., 1987b).

        DeBDE was identified at 20 µg/kg (dry weight) in one sample of 3
    estuarine sediment samples from Osaka but was not detected in samples
    from Tokyo, Matsuyama, or Hiroshima (Watanabe et al., 1987b).

        In 1987, an environmental survey was conducted concerning DeBDE in
    sediment in Japan. DeBDE was detected in 16 out of 60 samples at
    concentrations ranging from 10 to 1370 µg/kg (limit of determination
    7 µg/kg dry weight) in 1987 and was detected in 39 out of 129 samples
    collected at 43 locations at concentrations ranging from 4 to
    6000 µg/kg (limit of determination 4 µg/kg dry weight) in 1988-89
    (Environment Agency Japan, 1989, 1991).

        A sample was collected using a dredger, from the upper sediment
    layer of the Second Neya River in Osaka, Japan, in 1983. The sample
    contained approximately 0.2 mg DeBDE/kg dry weight (Watanabe et al.
    (1986).

        Yamamoto et al. (1991) analysed 20 sediment samples collected from
    the Kino River in Japan and found that DeBDE was present in all the
    samples. The concentrations ranged from 0.003 to 11.6 mg/kg dry
    weight.

        Zweidinger et al. (1978) found DeBDE at levels ranging from not
    detectable to 1 g/kg in sediment samples in the vicinity of a flame
    retardant manufacturing facility in the USA.

        DeBDE (limit of determination < 10 µg/kg) was found in sediment
    in the vicinity of bromine facilities in El Dorado and Magnolia,
    Arkansas (DeCarlo, 1979) and also in sludge samples from a
    discharge-treatment zone of a DeBDE facility in Bayonne, New Jersey
    (US EPA, 1988; IARC, 1990).

    5.1.4  Aquatic and terrestrial organisms

        One of 3 mussel samples, collected in 1981-85, from Osaka Bay,
    Japan, contained 1.4 µg DeBDE/kg (wet weight basis) (Watanabe, 1987;
    Watanabe et al., 1987a,b). DeBDE was not found in mullet, goby, sea
    bass, horse mackerel, sardine, mackerel, or hairtail from this area or
    in mussel, mullet, goby, sardine, mackerel, or hairtail from other
    locations (limit of determination < 0.5 µg/kg). A total of 17 samples
    were analysed.

        In 1987, an environmental survey was conducted concerning DeBDE in
    fish. It was not detected in 75 fish samples in 1987 and was not
    detected in 138 fish samples collected at 46 locations in 1988-89
    (limit of determination 5 µg/kg wet weight) (Environment Agency Japan,
    1989, 1991).

    5.2  Exposure of humans

    5.2.1  Occurrence of DeBDE in human tissues

        DeBDE was not found in 5 human adipose tissue samples obtained
    from a hospital in Osaka in 1985-86. The limit of determination was
    < 50 µg/kg fat (Watanabe, 1987; Watanabe et al., 1987a).

        DeBDE was detected at concentrations of up to 5 µg/kg in 2 out of
    40 samples of human hair obtained from barber shops in El Dorado and
    Magnolia, Arkansas (where the chemical is manufactured) in 1978
    (DeCarlo, 1979).

        In the USA, Cramer et al. (1990a,b) studied PBDD/PBDF levels in
    human fat tissue samples during 1987 (National Human Adipose Tissue
    Survey). The 865 specimens were combined to form 48 composites based
    on 9 census divisions and their age groups. The PBDD/PBDF analysis was
    carried out using HRGC/HRMS. No PBDD/PBDF were found (detection limit
    of 1-40 ng/kg, depending on congener). Identification of PBDE was
    based on comparison of full scan mass spectra of the samples with
    available standards, application of SIM techniques to compare
    theoretical ion ratios with observed ion ratios, and measurement of
    fragment losses from molecular ion clusters. Five samples were also
    monitored for DeBDE. No DeBDE was detected in 2 out of 5 samples; a
    weak DeBDE response was found in 1 out of 5 samples, and, in 2 out of
    5 samples, DeBDE was estimated at 400 and 700 ng/kg, respectively.

    5.2.2  Occupational exposure

        Wipe samples collected during an industrial hygiene survey in a
    DeBDE manufacturing plant in the USA, indicated that workers in the
    reactor area were exposed to 3.6 mg DeBDE/cm2. Personal samples
    collected from workers in the mill area indicated that the airborne
    levels of DeBDE ranged from 0.08 to 0.21 mg/m3, as a 8-h
    time-weighted average. Following a spill in the mill area, personal
    airborne levels ranged from 1.3 to 1.9 mg/m3 (Bialik, 1982).

        Human exposure to DeBDE occurs in the course of manufacture and
    use. Surveys have determined employee time-weighted average exposures
    of 1-4 mg/m3 in air with excursions up to 42 mg/m3 during short
    tasks. More than 90% of the particles in air were smaller than 10 µm
    in diameter. On the basis of its classification as a nuisance material
    by OSHA, the recommended workplace environmental exposure level in air
    is 5 mg/m3 (8-h time-weighted average for a 40-h week) (NTP, 1986)
    (see also section 4.2).

        Studies on worker exposure to PBDF/PBDD during the production of
    polymers containing PBDE are given in section 4.3.3.2.

    6.  KINETICS AND METABOLISM IN LABORATORY ANIMALS AND HUMANS

    6.1  Absorption and elimination

        Three male and 3 female Sprague-Dawley rats were administered
    orally 14C-labelled DeBDE suspended in corn oil. The elimination in
    urine and expired air was measured at 24-h intervals over a 16-day
    period. Less than 1% was found in urine and expired air. The principal
    route of elimination was via the faeces. Within 24 h, 90.6% of the
    14C activity was excreted and all the 14C was accounted for by day 2
    of the study. The data indicate that there is minimal absorption of
    DeBDE by the gastrointestinal tract (Norris et al., 1973, 1974,
    1975a,c; Dieter, 1979).

        As a supplement to the carcinogenicity studies (sections 7.3 and
    7.7), additional experiments were conducted to quantify DeBDE
    absorption from the gastrointestinal tract of male rats and to
    determine the effect of dose on absorption. Radiolabelled 14C-DeBDE
    (97.9-99.2%) was diluted with unlabelled DeBDE to yield the desired
    concentrations. DeBDE was mixed in the diet at approximate
    concentrations of 250, 500, 5000, 25 000, or 50 000 mg/kg, or was
    administered by intravenous injection. Animals were preconditioned by
    being fed diets containing the respective dose of unlabelled DeBDE for
    7 days before being fed diets containing 14C-DeBDE for 1 day, then
    being returned to diets containing unlabelled material for the
    remainder of the holding period. Results indicated that, after
    exposure to all doses in the diet, more than 99% of the radioactivity
    recovered was eliminated in the faeces within 72 h. Excretion in the
    urine accounted for approximately 0.01% or less of the dose. The high
    14C-DeBDE content of the gastrointestinal tissues was attributed to
    intimate contact with the diet. Concentrations of DeBDE in other
    tissues were near the limits of determination.

        After an intravenous dose of 1 mg/kg, 61% of the recovered
    radioactivity was eliminated in the faeces in 72 h and approximately
    0.1% in the urine.

        Estimates indicate that 0.33% ± 0.19% of the 50 000 mg/kg dose was
    absorbed. Data for the 25 000 mg/kg diet showed that the percentage of
    the dose absorbed was not significantly different from that of the
    highest dose. Radioactivity present in the lives following exposure in
    the diet was confirmed as DeBDE. However, the minimal absorption of
    DeBDE from the gastrointestinal tract, and, presumably, from other
    potential routes of exposure may explain the low toxicity of DeBDE
    (NTP, 1986; El Dareer et al., 1987).

    6.2  Distribution

        The distribution of radioactivity was measured in various tissues
    by Norris et al. (1973, 1975a,c). On day 16, no 14C-activity was
    found in the tissues, with the exception of 0.01% of the administered
    dose/g in the adrenal glands and 0.06% in the spleen.

        In studies in which concentrations of 14C-labelled DeBDE of
    250-50 000 mg/kg diet were fed to male Fischer 344 rats, more than 99%
    of the radioactivity was recovered in the faeces and intestinal
    contents (see section 6.1). The liver contained approximately 0.5% of
    the consumed dose, 24 h after feeding, and this declined to 0.016%
    after 72 h. Labelled material was extracted from the liver and found
    to be mainly unchanged DeBDE. Trace amounts of label were found in the
    kidneys, spleen, lung, brain, muscle, fat, and skin. Seventy-two hours
    following an intravenous dose of "C-labelled DeBDE, the faeces and gut
    contents contained 74% of the dose, suggesting significant binary
    excretion. Of the extracted faecal label, 63% were metabolites of
    DeBDE and 37% unchanged DeBDE. Labelled materials were found in the
    liver, kidneys, and lungs and in lower concentrations in muscle, skin,
    and fat (NTP, 1986; El Dareer et al., 1987).

        Rats were administered DeBDE in the diet at 0, 25, or 50 g/kg to
    determine the concentrations of DeBDE in the liver. The mean
    concentrations in the livers were 0.21 ± 0.43 (9), 2.09 ± 0.89 (8),
    and 8.6 ± 2.83 mg/kg liver (20), respectively. The number of livers
    studied is given in brackets (Rogers & Hill, 1980) (no details
    available).

    6.3  Retention and turnover

        A 2-year tissue accumulation study on the rat was carried out.
    Groups of 3 male and 3 female Sprague-Dawley rats were maintained on
    diets providing 0, 0.01, 0.1, or 1.0 mg DeBDE (FR-300 BA)/kg body
    weight per day for designated periods of time. The tissues/organs
    analysed for total bromine content were serum, adipose tissue, liver,
    kidneys, skeletal muscle, and testes (see section 7.3.1.2). Interim
    results after 10, 30, 90, 180 days, and 12 and 18 months of exposure
    showed that the total bromine values in serum, liver, kidneys,
    skeletal muscle, and testes were comparable with the control values.

    The mean total bromine content of adipose tissue showed a time- and
    dose-related (significant) increase, especially in the groups
    receiving 0.1 and 1.0 mg DeBDE/kg per day. Although there was a
    continuing increase in total bromine content, the concentrations in
    adipose tissue of rats ingesting 0.01, and 0.1 mg DeBDE/kg per day for
    23-24 months were 2.8 ± 0.9, and 7.5 ± 3.0 mg/kg, respectively,
    compared with 2.0 ± 0.2 mg/kg for the control rats. In the liver, the
    concentrations for the controls and the rats treated with 1.0 mg/kg
    were 2.9 ± 0.2 and 5.9 ± 1.1, respectively. In serum, after 23-24
    months, the concentrations for the 4 groups were 8.0 ± 1.2 (control),
    9.1 ± 1.1 (0.01 mg/kg), 7.9 ± 0.6 (0.1 mg/kg) and 8.1 ± 1.0
    (1.0 mg/kg) (Norris et al., 1974, 1975a; Kociba et al., 1975, 1975a).

        The elimination of bromine from tissues was studied in male
    Sprague-Dawley rats maintained for 90 days on a diet providing a dose
    of 1.0 mg DeBDE/kg per day, and then on a control diet. Four rats out
    of each group were sacrificed on the last day of exposure or after a
    recovery period of 0, 10, 30, 60, or 90 days. Serum, kidneys, adipose
    tissue, and liver were analysed. The low level of total bromine
    accumulated in adipose tissue remained unaffected during 90 days of
    recovery. Bromine was cleared from the liver within 10 days of
    recovery (Norris et al., 1974, 1975a,c).

        The half-life for the disappearance of 14C-activity from the body
    of DeBDE-treated rats was less than 24 h. The principal route of
    elimination was the faeces. No sex-related differences were found.
    14C-activity was rapidly cleared in DeBDE-treated rats.

    7.  EFFECTS ON LABORATORY MAMMALS AND IN VITRO TEST SYSTEMS

        The toxicological information on DeBDE has been summarized in
    several publications including: Norris et al. (1973, 1974, 1975a,b,c),
    AIHA (1981), and NTP (1986).

    7.1  Single exposure

    7.1.1  Oral: Rat

        Intragastric intubation of single doses of 126-2000 mg commercial
    DeBDE/kg body weight, as a 10% corn oil suspension, to female
    Sprague-Dawley rats (Spartan strain), did not produce any indications
    of toxicity or gross pathological changes during a 14-day period
    (Norris et al., 1973, 1974, 1975a,c).

        Groups of 5 male Spartan rats received single oral doses of up to
    5 g/kg body weight, by gavage, as suspensions in corn oil. No deaths
    occurred and the animals showed normal weight gain during a 14-day
    observation time. The acute oral LD50 in rats was >5 g/kg body
    weight (Great Lakes Chemical Corporation, undated b).

    7.1.2  Dermal Rabbit

        Commercial DeBDE was applied and to the occluded, clipped, intact
    skin of 2 male and 2 female New Zealand white rabbits, each at a
    dosage of 200 or 2000 mg/kg body weight, for 24 h. Observation time
    was 14 days. No mortality occurred. The acute dermal LD50 in rabbits
    was >2 g/kg body weight (Great Lakes Chem. Corp., undated b).

    7.1.3  Inhalation: Rat

        Groups of 10 male and 10 female Spartan rats were exposed for 1 h
    to concentrations of commercial DeBDE of 2 or 48.2 mg/litre air and
    subsequently observed for 14 days. All rats survived. At 2 mg/litre,
    salivation was noted in 2 rats on the first day, but, from there on,
    all the rats in this group appeared normal, except one with
    respiratory difficulties and another with ocular discharge during the
    observation period. At 48.1 mg/litre, eye squint and increased motor
    activity were noted in the animals up to day 4. Respiratory
    difficulties were noted in 2 rats on days 3-6 and in one rat on day 8
    and one on day 7. A few rats showed eye squint and ocular discharge on
    days 7-12. All rats were normal on day 14. The acute inhalation LD50
    in rats was >48.2 mg/litre (Great Lakes Chemical Corporation,
    undated b).

    7.2  Short-term exposure

    7.2.1  Oral

    7.2.1.1  Mouse

        In a 14-day study, groups of 5 B6C3F1 mice, of each sex, were
    exposed to DeBDE (99%) in the diet at concentrations of 0, 20, 50, or
    100 g/kg. No effects on health, survival, or body weights were
    observed and no compound-related clinical signs or gross pathological
    effects were reported (NTP, 1986).

        In a 13-week study, groups of 10 male and 10 female B6C3F1 mice
    were administered DeBDE (two lots of DeBDE were used; one of 99% and
    the other > 97%) in the diet at 0, 31, 62, 12.5, 25, or 50 g/kg, for
    13 weeks. No evidence was found for compound-related effects on
    physical appearance, behaviour, food consumption, body weight gain,
    survival, and gross and microscopic pathology. This study was used to
    establish the dose levels for the long-term study (Rutter & Machotka,
    1979; NTP, 1986).

    7.2.1.2  Rat

        In 3 separate, 28-day feeding studies, each with groups of 10 male
    and 10 female Charles River CD rats, commercial DeBDE was administered
    at 0, 100, or 1000 mg/kg diet. The rats were observed for appearance,
    mortality, food consumption, body weight gain, and organ weights.
    After sacrifice, gross pathological and microscopic examinations of
    the liver, kidneys, and thyroid were carried out. Adverse effects or
    lesions associated with DeBDE administration were not found in these 3
    rat studies. The total bromine contents of the liver, and adipose
    tissue were determined and a slight increase in bromine concentration
    was found at the highest dose level (Great Lakes Chemical Corporation,
    undated b) (no details available).

        Groups of 5 male Sprague-Dawley rats were administered a diet
    containing 0, 0.01, 0.1, or 1.0% [equivalent to 0, 8, 80, or 800 mg
    DeBDE (77.4% DeBDE, 21.8% NBDE, and 0.8% OBDE)/kg body weight per
    day], for 30 days. No influence on food intake or body weight gain was
    found. No haematological changes were observed in the 8 and 80 mg/kg
    dose groups, but, at 800 mg/kg, there were decreases in packed cell
    volume and red blood cell count. Urinalysis parameters were not
    affected at any dose level. No differences in heart, testes, brain,
    and kidney weights were observed. Enlarged livers were found in rats
    exposed to 80 and 800 mg DeBDE/kg. The liver lesions consisted of
    centrolobular cytoplasmic vacuolization. Furthermore, in the rats
    receiving 80 and 800 mg/kg, hyaline degenerative cytoplasmic changes
    in the kidneys and thyroid hyperplasia were found. At a dietary level
    of 0.1 g/kg (equivalent to 8 mg/kg body weight), no treatment-related
    changes in the liver or thyroid, or other changes were found. (Remark:
    limited histopathology was carried out) (Sparschu et al., 1971; Norris
    et al., 1973, 1974, 1975a; Kociba et al., 1975a).

        In a 14-day study with DeBDE (99%) administered in the diet to
    Fischer 344/N rats at concentrations of 0, 5, 20, 50, or 100 g/kg, no
    effects were seen on health, survival, and body weight, and no
    compound-related clinical signs or gross pathological effects were
    observed. Similarly, no toxic effects were seen in a 90-day study in
    which doses of DeBDE (>97%) of 0, 3.1, 6.2, 12.5, 25, or 50 g/kg were
    administered in the diet. No effects on survival, body weight, or feed
    consumption were observed. No gross or microscopic effects were
    reported. Liver weights were not recorded in these studies, but, in
    subsequent studies, liver weights were significantly increased in
    Fischer 344/N rats at dose levels of 25 and 50g DeBDE (92%)/kg diet,
    for 14 days (NTP, 1986).

    7.2.2  Inhalation

    7.2.2.1  Rat

        Pulmonary tissue response and pulmonary clearance of commercial
    DeBDE were evaluated following intratracheal administration of the
    dust to rats. The study was conducted to evaluate the possible health
    hazards for man from inhalation of the dust generated during the
    production and handling of DeBDE. Fifty male, Sprague-Dawley rats were
    given an intratracheal injection of 20 mg DeBDE (77.4%) dust (length
    mean diameter 2.65 µm, surface mean diameter 2.91 µm, and volume mean
    diameter 3.17 µm) suspended in 1 ml of rat serum. A control group of
    35 rats received only the serum vehicle. The rats were observed for
    appearance, demeanour, and body weights. Groups of 5 treated and 2
    control rats were killed on days 3, 10, 30, 91, and 365 for
    determination of total bromine content in the lungs. The calculated
    DeBDE equivalent values were used to determine the half-life of DeBDE
    in lungs, which was determined to be 150 days. To assess the
    respiratory tissue response, gross and histopathological examinations
    were conducted on rats killed on days 10, 30, 416, and 556 and on rats
    that died. No untoward effects were observed, except on days 10 and
    556 (but not on days 30 and 416): the lungs of treated rats contained
    scattered focal aggregates of alveolar macrophages showing clear,
    angulated, cytoplasmic vacuoles or spaces, which probably represented
    the location of the dust particles. A very slight focal thickening of
    the interalveolar septae was noted in 2 out of 5 rats. Particles were
    not present in the regional lymph nodes. No evidence of fibrosis or
    other proliferative response was detected in the lungs or regional
    lymph nodes (Jersey et al., 1976).

    7.3  Long-term exposure

    7.3.1  Oral

    7.3.1.1  Mouse

        A two-year study was carried out on B6C3F1 mice. The animals were
    administered DeBDE in the diet at concentrations of 0, 25, or 50 g/kg,
    for 113 weeks (NTP, 1986) (for details of the study see section
    7.7.1.1).

    7.3.1.2  Rat

        A long-term/carcinogenicity study was carried out on
    Sprague-Dawley rats administered daily doses of 0, 0.01, 0.1, or
    1.0 mg DeBDE/kg body weight in the diet for 2 years (Kociba et al.,
    1975, 1975a; Norris et al., 1975a,b). In another 2-year study, Fischer
    344 rats were administered DeBDE at 0, 25, or 50 g/kg diet (NTP, 1986)
    (for details of these 2 studies see section 7.7.1.2).

    7.4  Skin and eye irritation; sensitization

    7.4.1  Skin irritation

        Skin irritation studies conducted with commercial DeBDE, applied
    as a dry solid (500 mg) on the shaved skin (under occlusion) of 2
    groups of 3 New Zealand white rabbits caused no irritation on intact
    skin and no, or only slight, erythematous and oedematous responses on
    abraded skin, after a single exposure for 24 h and an observation
    period of 72 h. A comparable study on 3 male and 3 female New Zealand
    white rabbits in which 500 mg DeBDE was applied on intact or abraded
    skin showed no skin irritation. Repeating the exposures of intact skin
    for 5 days/week for 2 weeks or to abraded skin for 3 days did not
    alter the response (Norris et al., 1973, 1974, 1975a,c; Great Lakes
    Chemical Corporation, undated c).

    7.4.2  Eye irritation

        Eye irritation studies on 3 male and 3 female New Zealand White
    rabbits showed that 100 mg Saytex 102/eye, applied as a dry solid,
    caused only transient irritation (redness and chemosis) of the
    conjunctival membranes. The cornea, iris, and lens were unaffected
    (sodium fluorescein and UVR were used). After 24 h, the eyes had
    recovered. The observations were made at 1, 24, 48, 72 h, and 7 days
    after treatment (Norris et al., 1973, 1974, 1975a,c; Ethyl Corp.,
    1986; Mallory et al., 1986; Great Lakes Chemical Corporation,
    undated c).

    7.4.3  Sensitization

        Repeated application of a suspension of 5% DeBDE (77.4% DeBDE,
    21.8% NBDE, 0.8% OBDE) in petrolatum, 3 times a week for 3 weeks, to
    the skin of 50 human volunteers did not result in skin sensitization
    reactions during the sensitizing period or, on challenge 2 weeks
    following the last application. Skin irritation was observed in 14 out
    of the total 450 applications (11 of the reactions were classified as
    very slight and 3 as mild erythema). These reactions were seen in 9
    out of the 50 persons (Norris et al., 1974, 1975a,c; Dow Chemical
    Comp. USA, 1978).

    7.4.4  Chloracnegenic activity

        Chloracnegenic activity was studied on the ear of each of 4 New
    Zealand White male and female rabbits. The test material (Saytex 102)
    was administered once daily at 0.1 ml/day, 5 times per week, for 4
    weeks, at concentrations of 1, 10, 100, or 1000 g/kg, in chloroform.
    Observations were recorded prior to the initial dose and at 7, 14, 21,
    and 28 days of dosing. Saytex 102 as a 10% chloroform solution caused
    a slight erythematous response and slight exfoliation, but no
    chloracne was observed during the study (Naismith & Matthews 1981).

        In the period 1971-74, approximately 40 samples of DeBDE (pilot
    plant samples), mother liquor, mother liquor still pot residue, and
    still bottom samples were studied for their chloracnegenic activity.
    In these studies, the samples (0.1 ml) were applied as such, or as a 5
    or 10% solution in chloroform, on the rabbit ear, 5 days per week for
    4 weeks. The samples of DeBDE did not induce any responses, but
    responses to the mother liquor and still bottom samples were positive,
    except in a few cases where the result was equivocal (Rampy, 1971-74).

    7.5  Reproductive toxicity, embryotoxicity, and teratogenicity

    7.5.1  Reproductive toxicity

        A one-generation reproduction study was performed in which 10
    male, and 20 female, Sprague-Dawley rats at the two lower dose levels
    (3 and 30 mg/kg body weight) and 15 male and 30 female rats at the
    higher dose level (100 mg/kg body weight) were given commercial DeBDE
    with the diet (weekly adjustment), for 60 days prior to mating, 15
    days during mating, and subsequently throughout gestation and
    lactation. Twenty male and 40 female rats served as controls. No signs
    of toxicity were observed in the adult rats or the neonates during the
    study or at necropsy. Unaffected parameters included body weight gain
    and food consumption by adults, reproductive parameters (the
    percentage pregnant and neonatal growth, survival, and development),
    preterminal urinalysis and clinical chemistry in adult rats, gross
    examination of all adult and weanling rats, and microscopic
    examination of tissues from both age groups. No cytogenetic changes
    were observed in the bone-marrow of parents and weanling rats. Thus,
    no toxicological manifestations were associated with the ingestion of
    100 mg DeBDE/kg in this reproduction study (Norris et al., 1975c;
    Schwetz et al., 1975).

    7.5.2  Teratogenicity

        Pregnant female rats were given 0, 10, 100, or 1000 mg commercial
    DeBDE/kg body weight, suspended in corn oil, by intragastric gavage,
    on days 6-15 of gestation.

        Maternal food consumption and body weight did not differ from
    those of the controls. Liver weights of the mothers were comparable
    with those of the control animals. The position and number of fetuses
     in utero, the number of  corpora lutea, individual pup weight,
    crown-rump length, and sex ratio, were similar to those of the
    controls.. A significant increase in resorptions was found at low dose
    levels, but not at the high dose level. No gross external
    abnormalities were seen in the fetuses of dams treated at any dose
    level. Soft tissue and skeletal examinations revealed an increased
    number of litters with subcutaneous oedema and delayed ossification of
    bones of the skull of fetuses of dams treated with 1000 mg/kg, but not

    with 100 mg/kg body weight. Analysis of maternal and fetal livers for
    total bromine revealed a significantly increased concentration in
    maternal livers of rats treated with 1000 mg/kg. Treatment with
    100 mg/kg or less did not produce any increase in total bromine
    contents. No increase in total bromine contents was observed in the
    livers of fetuses from dams receiving any of the dose levels of DeBDE
    (Norris et al., 1973, 1974, 1975a; Hanley, 1985; US EPA, 1989).

    7.6  Mutagenicity and related end-points

    7.6.1  Mutation

        A technical product, HFO 102, was tested in a  Salmonella
     typhimurium assay with the strains TA 98, TA 100, TA 1535, and TA
    1537 with, or without, metabolic activation. The HFO 102 was not
    completely soluble in DMSO at a concentration of 10 mg/litre. However,
    the suspension was used for the test and for preparation of the
    solutions. The dose levels that were tested were 0.4, 4.0, 40, and
    1000 µg/plate. No evidence for mutagenic activity was found (Shoichet
    & Ehrlich, 1977).

        Results of studies with  Saccharomyces cerevisiae with, or
    without, liver microsomal enzyme preparations, were also negative (no
    details) (Great Lakes Chemical Corporation, undated b).

        Commercial DeBDE in concentrations of 100-10 000 µg/plate was not
    mutagenic in  Salmonella typhimurium, TA 100, TA 1535, TA 1537, and
    TA 98 strains, in the presence, or absence, of an exogenous metabolic
    system from Aroclor 1254-induced male rat liver S9 and male Syrian
    hamster liver S9 (NTP, 1986).

    7.6.2  Chromosomal effects

        Cytogenetic examination of bone marrow cells, taken at necropsy
    from the femur of the parent animals from a reproduction study (see
    section 7.5.1) as well as from the neonates at weaning, showed no
    increase in cytogenetic aberrations compared with the controls (Norris
    et al., 1975c) (no details).

        Commercial DeBDE was not mutagenic in the mouse lymphoma
    L5178Y/TK+/- assay in the presence, or absence, of Aroclor
    1254-induced male F344 rat liver S9. Tests for cytogenic effects in
    Chinese hamster ovary cells indicated that commercial DeBDE does not
    cause chromosomal aberrations or sister-chromatid exchanges in either
    the presence or absence of S9, prepared from livers of Aroclor
    1254-induced male Sprague-Dawley rats (NTP, 1986).

    7.7  Carcinogenicity

    7.7.1  Oral

    7.7.1.1  Mouse

        Groups of 50 male and 50 female B6C3F1 mice (nine weeks old) were
    fed 0, 25, or 50 g DeBDE (purity 94-99%; no brominated dioxins or
    furans were found)/kg diet for 103 weeks; all survivors were killed in
    weeks 112-113. The average daily consumption of DeBDE was estimated to
    be 3200 mg/kg for low-dose and 6650 mg/kg for high-dose male mice and
    3760 mg/kg for low-dose and 7780 mg/kg for high-dose female mice. Body
    weights and survival of treated animals were comparable with those of
    the controls. Non-neoplastic lesions observed in treated mice were
    granulomas in the liver of low-dose males and hypertrophy in the liver
    of low- and high-dose males. The combined incidence of hepatocellular
    adenomas and carcinomas was significantly increased in males: control
    8/50, low-dose 22/50, and high-dose 18/50 (but not increased in
    comparison with historical control groups); the combined incidence of
    thyroid gland follicular-cell adenomas and carcinomas was increased,
    but not significantly, in treated males: control 0/50, low-dose 4/50,
    high-dose 3/50; females: control 1/50, low-dose 3/50, high-dose 3/50.
    Follicular-cell hyperplasia of the thyroid gland was increased in both
    groups of treated male and female mice (NTP, 1986; Huff et al., 1989).

    7.7.1.2  Rat

        Groups of 25 male, and 25 female, Sprague-Dawley rats, 6-7 weeks
    of age, were fed 0, 0.01, 0.1, or 1.0 mg DeBDE/kg body weight (purity
    DeBDE 77.4%, nonabromodiphenyl ether 21.8%, octabromodiphenyl ether
    0.8%) in the diet for 100-105 weeks. Additional groups of 10-34
    rats/sex per dose level were killed at various times during the study
    to investigate the accumulation of total bromine in the tissues.
    Ingestion of up to 1.0 mg DeBDE/kg did not influence survival rates;
    appearance, mean body weights, feed consumption, haematology,
    urinalysis, clinical chemistry, and organ weights of treated groups
    were similar to those of controls. No discernible toxicological
    effects were produced by DeBDE and no significant differences in the
    number of rats developing tumours, the total number of tumours, or the
    specific type of tumours were observed between treated and control
    groups, when evaluated by the Fisher's exact probability test. Adrenal
    phaeochromocytomas were the most frequent tumours in the male rats in
    all groups. During the study, there was a slight build up of the total
    bromine content in the tissues of rats ingesting the 2 highest dose
    levels, as measured by neutron activation analysis. However, the
    source of bromine may, or may not, have been DeBDE, because NBDE and

    OBDE were also present in the product. Serum, muscle, and kidneys did
    not show any increase in total bromine content. In the liver,
    low-level, steady-state conditions were attained by 12 months. Adipose
    tissue showed a time- and dose-related increase in total bromine
    content, subsequent to ingestion of 0.1 or 1.0 mg/kg. The total
    bromine content of adipose tissue of rats ingesting 0.01 mg/kg for 2
    years was 2.8 ± 0.9 mg/kg compared with a control value of 2.0 ±
    0.2 mg/kg (section 6.3) (Kociba et al., 1975, 1975a; Norris et al.,
    1975a,b). [The IARC Working Group (1990) noted the very low dose
    levels used].

        Groups of 50 male, and 50 female, Fischer 344/N rats, 7-8 weeks of
    age, were fed DeBDE (purity 94-99%; no brominated dioxins or furans
    were found) at 0, 25 or 50 g/kg diet, for 103 weeks; all survivors
    were killed in weeks 111-112. The average daily consumption of DeBDE
    was estimated to be 1120 and 2240 mg/kg for low-dose and high-dose
    male rats, respectively, and 1200 and 2550 mg/kg for low-dose and
    high-dose female rats, respectively. Body weights of treated rats were
    not significantly different from those of the controls. Thrombosis and
    degeneration of the liver, fibrosis of the spleen, and lymphoid
    hyperplasia were observed in high-dose male rats. Significant
    increases were observed in the incidence of neoplastic nodules of the
    liver (adenomas) in treated males: control 1/50; low-dose 7/50;
    high-dose 15/49 and females: control 1/50; low-dose 3/49; high-dose
    9/50. No differences in the incidence of hepatocellular carcinomas
    were seen among the groups. The incidence of acinar-cell adenomas of
    the pancreas in males was: control 0/49; low-dose 0/50; high-dose
    4/49. The difference between the controls and the high-dose group was
    not significant. A high incidence of mononuclear-cell leukaemia was
    observed in treated and control rats of both sexes (NTP, 1986; Huff et
    al., 1989).

    7.8  Other special studies

    7.8.1  liver

        Carlson (1980a) administered commercial DeBDE (in corn oil), by
    gavage, at a dose of 0.1 mmol/kg body weight to male Sprague-Dawley
    rats (200-250 g) for 14 days. Twenty-four hours after the last
    (seventh) dose, the liver/body weight ratio increased. Koster et al.
    (1980) found no evidence of a porphyrinogenic action after exposure of
    cultures of chick embryo liver cells to a concentration of 5 µg DeBDE
    (in DMSO)/ml medium with, or without, pretreatment with
    naphthoflavone, an inducer of P450, P448, and of delta-levulinic acid
    synthethase.

        A sample of DeBDE, obtained from the NTP repository, was
    administered by gavage (vehicle not clear) at 1500 mg/kg body weight
    to 9, three-month-old, female Sprague-Dawley (CD) rats, 21 h and 4 h
    before they were killed. No changes were observed in hepatic
    cytochrome P450 content, hepatic DNA damage, as determined by alkaline
    elution, hepatic ornithine decarboxylase activity, or serum alanine
    aminotransferase activity (Kitchin et al., 1992).

    7.8.2  Miscellaneous

        Hefner (1973) studied, in an  in vitro model, the rupture of
    erythrocyte membranes (haemolysis) induced by dust particles. The test
    approximates the  in vivo rupture of the secondary lysosomal
    membranes. Fibrogenic dusts are capable of rupturing the erythrocyte
    membrane, while non-fibrogenic dusts are not. On the basis of the
     in vitro model, DeBDE of the particle size studied (shown by optical
    microscopy to have a 2.65 µm number length mean diameter with 94.5% of
    the particles being 3.77 µm and below) appears to be non-fibrogenic
    (only 0.1% haemolysis) at 115 mg dust/ml suspension and time from 15
    to 120 min.

    7.8.3  Toxicity of soot, char, and other waste products from
           combustion of DeBDE-containing polymers

    7.8.3.1  Acute oral toxicity

        Groups of 5 male, and 5 female, Sprague-Dawley rats were
    administered a mixture of soot and char (61/39%), generated from the
    combustion of high-impact polystyrene, as a single dose, by garage at
    0(vehicle), 0.5, 5.0, 50, 500, or 2000 mg/kg body weight. These
    amounts were given in 10 ml 1% methyl cellulose/kg body weight.
    Observation time was 28 days. Body weight gain, mortality, and weights
    of 10 organs were studied, and these organs in the control and 2000 mg
    groups were also examined microscopically. No overt signs of toxicity
    were observed. The acute oral LD50 was >2 g/kg body weight (Fulfs &
    Dahlgren, 1987a).

        The acute toxicity of the combustion products of a matrix composed
    of high-impact polystyrene, DeBDE, and antimony trioxide was
    investigated. Six dose groups of 5 male and 5 female rats were
    treated, by gavage, with 0, 0.5, 5, 50, 500, or 2000 mg/kg of combined
    soot and char, generated from the combustion of the flame retarded
    high-impact polystyrene (HIPS) suspended in 1% methyl cellulose and
    observed for 28 days. No animals died during the course of the study
    and no clinical signs of toxicity were observed. No histological
    lesions were detected in the following organs examined: thyroid,
    parathyroid, and adrenal glands, spleen, gonads, heart, liver, lung,
    brain, kidneys, and thymus. The LD50 was > 2000 mg/kg body weight
    (Fulfs & Dahlgren, 1987b; Pinkerton et al., 1989).

        Undiluted solids from mother liquor (waste tars) were tested for
    acute oral toxicity in rats. No acute oral lethality was seen with
    0.126 g/kg body weight in corn oil, but 100% mortality was found, with
    0.5 g in water. The animals displayed tremors (Norris, 1971).

    7.8.3.2  Skin irritation and comedogenicity

        Soot and char generated from the combustion of high-impact
    polystyrene retarded with, or without, DeBDE and Sb2O3 were tested
    for their comedogenicity using a New Zealand albino rabbit ear
    bioassay (Draize, 1979). The soot and char samples were mixed in
    different ratios. The dose levels were; 0.001, 0.003, 0.005, 0.008,
    0.01, 0.03, 0.05, 0.08, and 0.1 g. The highest dose level (0.1 g) of
    the mixture was actually in excess of the amount that remained on the
    ear. The materials were applied in 0.1 ml of water. Five male rabbits,
    with 2 healthy ears each, were randomly selected for these studies and
    the original design required 10 exposure levels, 1 per ear. Dosing was
    continued for 5 consecutive days. Ears were checked to grade the
    erythema on day -1 and day 0, and then daily, and the final grading
    was done on the day following the last dosing. The results showed
    that, without flame retardants, very slight to well defined erythema
    occurred with doses of 0.005 g and higher. In cases where the polymer
    was flame retarded, the effect was stronger, very slight to
    moderate/severe erythema occurred with doses of 0.001-0.003 g or more
    (see Table 24) (Fulfs 1987a,b).

        Table 24.  Skin irritation by soot or char generated from the combination of
               HIPS with, or without, DeBDE
                                                                                   

    Soot/char            Mixture         Dose           Erythema score
                         soot/char
                                                                                   

    High impact          61/39%        0.005 g and    score 1-2 (increasing
    polystyrene                        higher         with dose level from
                                                      day 2 onwards)

    High impact          47/63%        0.003 g and    score 1-3 (increasing
    polystyrene with                   higher         with close level, from
    DeBDE and antimony                                day 1)
    trioxide
                                       0.001 g and    same result, increasing
                                       higher         from day 3

                                                                                   
    
        Two groups of four (mainly 2 male and 2 female) New Zealand white
    rabbits were used to test a mixture of soot and char (61/39%),
    generated from the combustion of high-impact polystyrene treated
    without flame retardants, in a rabbit ear comedogenicity bioassay.
    Daily dose levels of 2, 5, 8, 20, or 50 mg of the mixture were
    administered. Each daily dose was rubbed with 0.1 ml of water on the
    inner surface of the pinna of one ear of the respective rabbit. The
    animals were dosed 5 days per week for a total of 4 weeks. The total
    cumulative dose levels were 40, 100, 160, 400, and 1000 mg. The ears
    were graded for irritation (Draize test) and for hyperkeratosis (Adams
    test). During the study, dermal irritation was found in all treated
    groups with a score of 1-2. No comedogenic (score 0) responses were
    observed on any of the ears. A slight increase in hyperkeratosis of
    the sebaceous follicles was seen during histopathological examination
    of the skin in the animals treated with the 2 highest dose levels. No
    evidence of overt toxicity was seen among any of the animals tested
    (Fulfs & Dahlgren, 1987c; Pinkerton et al., 1989).

        A similar study was carried out with a combined soot and char
    (47/53%) mixture, generated from the combustion of HIPS flame retarded
    with DeBDE and antimony trioxide. The results were comparable with
    those of the combustion products of HIPS without flame retardants.
    There was no microscopic evidence of any significant hyperkeratotic
    response (Fulfs & Dahlgren, 1987d).

        Undiluted solids from mother liquor (waste tars) were tested for
    skin irritation in rabbits. Slight skin irritation was observed at a
    dose of 1.1 g/day for 3 days (Norris, 1971).

    7.8.3.3  Eye irritation

        Solids from mother liquor (waste tars) were tested for eye
    irritation. The material is a mixture of brominated DeBDE (Br = 7-10).
    A dose of 0.1 g of the mixture caused severe eye irritation and slight
    corneal injury (Norris, 1971).

    8.  EFFECTS ON HUMANS

    8.1  General population exposure

        No data are available.

    8.2  Occupational exposure

    8.2.1  Skin sensitization

        Human volunteers (80 males and 120 females) were treated with 9
    induction patches of 2 batches of DeBDE, identified as DBDO-1 and XD
    8186.02. The first sample was evaluated as such, and the second as a
    2% (w/v) aqueous solution. The upper arm was used in the males and the
    upper back in the females. The patches were applied once every 2 days

    and the substance left in contact with the skin for 24 h, after which
    it was removed. After the application of 9 patches, there followed a
    non-patching period of 12 days, after which the challenge patch was
    applied to detect sensitization. A new skin site was used for this
    24-h patch. After removal of the patch, reactions were observed after
    24 and 48 h. This study did not reveal any evidence of skin
    sensitization with either test material in any of the subjects
    (Industrial Bio-test Laboratories, 1975).

    8.2.2  Neurotoxicity

        A health assessment of workers exposed to polybrominated biphenyls
    and polybromodiphenyl ethers, e.g., DeBDE, during manufacture revealed
    a higher than normal prevalence of primary hypothyroidism and a
    significant reduction in sensory and fibula motor velocities; no other
    dermatological or neurological effects were seen. The authors could
    not conclude whether these effects were caused by DeBDE or by PBB,
    which was also produced (earlier) in the plant. DeBDE was not detected
    in the serum of the workers (Bahn et al., 1980).

    8.2.3  Epidemiological studies

        The health of workers in facilities where flame retarded polymers
    were extruded has been evaluated in 3 studies, 2 at Celanese and 1 at
    General Electric (BFRIP, 1990).

        A study was conducted by Celanese Corporation in the late 1970s at
    their Bishop, Texas, facility. The primary purpose of this study,
    conducted by Tabershaw Associates, was to investigate the possible
    effects of employee exposure to formaldehyde. However, brominated
    flame retardants have been used at the facility since 1970, and,
    therefore, significant effects resulting from the use of these
    materials might also have been revealed by the study. No effects that
    might be attributable to the use of the brominated flame retardants
    were observed (EBFRIP, 1990).

        A more complete study was conducted by General Electric Plastics
    at their Mt. Vernon, Indiana, facility early in 1988. In the
    conclusions of the study, it is stated that "there appears to be no
    evidence that the workers in the study zone display any symptoms
    associated with exposure to dioxins or related substances. More
    critically, as a statistical group, the general medical examinations
    for these workers compare very favorably with the examination for the
    workers in the control zone or with published values for the general
    population". It is finally concluded that "the study gives reasons to
    continue to be observant but no reason to be alarmed" (EBFRIP, 1990).

        A comprehensive medical evaluation of workers involved in the
    processing of polymers containing brominated flame retardants was
    undertaken at the BASF facility in Ludwigshafen, Germany. In this
    study, some 40 potentially exposed workers and an equivalent number of
    workers from a control group were subjected to complete medical and
    psychological examination. The health of the workers compared
    favourably with workers in the control zones. None of the workers
    displayed symptoms associated with exposure to dioxin or related
    substances, therefore, it was concluded that the workers did not show
    any symptoms that could be associated with PBDD or PBDF emitted during
    the polymer processing. It should be kept in mind that there might
    also be exposure during the formulation of PBDE- containing polymers
    and from products made of these polymers. Furthermore, exposure to
    dusts may also occur (EBFRIP, 1990).

        Zober et al. (1992) carried out a morbidity study of extruder
    personnel with potential exposure to brominated dioxins and brominated
    furans. The presence of PBDF/PBDD in air was established through
    air-monitoring during the extrusion blending of
    polybutyleneterephthalate with DeBDE. Biomonitoring results of 42
    workers (exposed during the period 1975-88) and immunological tests
    for exposed and 42 control employees were presented. Among potentially
    exposed men, 2,3,7,8-TeBDF/TeBDD concentrations in blood lipid ranged
    from nd to 112 and from nd to 478 ng/kg, respectively. The control
    workers had concentrations of 7 and 7-48 ng/kg respectively. Results
    of the immunological studies showed that the immune system of exposed
    workers was not adversely affected at these burdens of TeBDF/TeBDD for
    up to 13 years.

    9.  EFFECTS ON OTHER ORGANISMS IN THE LABORATORY AND FIELD

        Marine unicellular algae,  Skeletonema costatum, Thalassiosira
     pseudonana, and Chlorella sp. were exposed to commercial DeBDE in 6
    algal growth media. The duration of the exposure was 72 h for
     S. costatum and T. pseudonana and 96 h for  Chlorella sp. The
    population density was estimated by cell counts using a
    haemocytometer. Inhibition by 1 mg DeBDE/litre acetone was less than
    50% in all species (Walsh et al., 1987).

    10.  PREVIOUS EVALUATIONS BY INTERNATIONAL BODIES

        An evaluation by IARC (1990) concluded that there is limited
    evidence for the carcinogenicity of DeBDE in experimental animals. No
    data were available from studies on the carcinogenicity of DeBDE in
    humans. Overall evaluation: DeBDE is not classifiable as to its
    carcinogenicity for humans (Group 3).

    NONABROMODIPHENYL ETHER

    1.  SUMMARY, EVALUATION, CONCLUSIONS AND RECOMMENDATIONS

        Nonabromodiphenyl ether is not manufactured or used. No data are
    available on the following topics:

    *   Environmental transport, distribution, and transformation

    *   Environmental levels and human exposure

    *   Kinetics and metabolism in laboratory animals and humans

    *   Effects on laboratory mammals and  in vitro test systems

    *   Effects on humans

    *   Effects on other organisms in the laboratory and field

    *   Previous evaluations by international bodies.

    1.1  Summary and evaluation

        There is no database on which to make an evaluation.

    1.2  Recommendations

        Levels of contamination of commercial brominated flame retardants
    with nonabromodiphenyl ether should be minimized to avoid
    contamination of the environment and exposure of humans.

    2.  IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, ANALYTICAL METHODS

    2.1  Identity

    Chemical structure:

    CHEMICAL STRUCTURE 3


    Chemical formula:             C12 H Br9 O

    CAS registry number:          63936-56-1

    Chemical name:                pentabromo(2,3,4,5-tetrabromophenoxy)-
                                  benzene

    Common name:                  nonabromodiphenyl ether (NBDE);
                                  nonabromodiphenyloxide

    Relative molecular mass:      880.37

        Based on the chemical structure, there are three possible isomers
    of nonabromodiphenyl ether.

        From: US EPA (1984, 1986).

    2.2  Physical and chemical properties

        No data are available.

    2.3  Analytical methods

        No specific data are available (see General Introduction section
    2.1 and Table 2).

    3.  SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE

    3.1  Natural occurrence

        NBDE has not been reported to occur naturally (see General
    Introduction section 1.1).

    3.2  Anthropogenic sources

    3.2.1  Production levels and processes

        Nonabromodiphenyl ether has been prepared from decabromodiphenyl
    ether by heating with NaSH in xylene at 130 °C for 2 h. The removal of
    the reactive Br in the  ortho-position of decabromodiphenyl ether led
    to the photostability of the product (Noguchi et al., 1977).

    3.2.2  Uses

        Nonabromodiphenyl ether is not used commercially as a flame
    retardant. It is present as an impurity in OBDE at a concentration of
    10%.

    OCTABROMODIPHENYL ETHER

    1.  SUMMARY, EVALUATION, CONCLUSIONS AND RECOMMENDATIONS

        Pure octabromodiphenyl ether is not manufactured or used. No data
    are available on the following topics:

    *   Kinetics and metabolism in laboratory animals and humans

    *   Effects on humans

    *   Effects on other organisms in the laboratory and field

    *   Previous evaluations by international bodies.

    1.1  Summary and evaluation

    1.1.1  Identity, physical and chemical properties

        Commercial OBDE is a mixture of approximately 11% PeBDE/HxBDE, 44%
    HpBDE, 31-35% OBDE, 10% NBDE, and 0.5% DeBDE. On the basis of the
    chemical structure, there are 12 possible isomers of OBDE and 24
    possible isomers of HpBDE.

        The melting point varies from about 80 °C to >200 °C. The vapour
    pressure is < 10-7 mmHg. The solubility in water is low and the
     n-octanol/water partition coefficient (log Pow) >5.5. The above
    variations in physical data may be explained by the differences in
    composition of the mixtures tested.

    1.1.2  Production and uses

        The worldwide consumption of commercial OBDE per year is 6000
    tonnes, 70% of which is used as a flame retardant in ABS for the
    production of computers and business cabinets. OBDE is the second most
    widely used PBDE flame retardant.

    1.1.3  Environmental transport, distribution, and transformation

        Components of commercial OBDE have been found in aquatic sediment
    and human fat. Some lower brominated components (HxBDE and PeBDE) of
    commercial OBDE have been found in biota. OBDE has not been detected,
    but HpBDE and NBDE have generally not been looked for. Commercial OBDE
    components are likely to be persistent but, as bromination levels rise
    beyond HxBDE, they are increasingly unlikely to bioaccumulate. A
    bioaccumulation factor of less than 2 has been found in carp for a
    commercial OBDE product.

        Pyrolysis of commercial OBDE, as such, or of polymers with OBDE as
    a flame retardant (with, or without, Sb2O3) at 600 °C has been shown
    to produce PBDF and, in much lower concentrations, PBDD. Processing of
    ABS with OBDE/Sb2O3 under different conditions, showed that under
    normal processing conditions, only low levels of PBDF were formed.
    Under abusive conditions, the concentrations were much higher. PBDD
    concentrations were low in both cases.

    1.1.4  Environmental levels and human exposure

        OBDE and the lower brominated components of commercial OBDE were
    not detected in water samples collected in Japan in 1987 and 1988.
    Sediment samples were also analysed and, in approximately 2-6% of the
    samples, OBDE was detected in concentrations ranging from 8 to
    22 µg/kg dry weight. Lower brominated components were also found in
    the sediment.

        OBDE was not detected in fish samples collected in Japan in 1987
    and 1988.

        In the USA, samples of human fat were investigated for the
    presence of PBDF and PBDD in 1987. The samples were derived from 865
    specimens combined to form 48 composite analogues. The composite
    design was based on 9 census divisions and 3 age groups. In these
    samples, PBDE were also identified and preliminary evidence showed the
    presence of OBDE at a frequency of 60% and an estimated concentration
    of up to 8000 ng/kg.

    1.1.5  Kinetics and metabolism in laboratory animals and humans

        No data are available.

    1.1.6  Effects on laboratory mammals and  in vitro test systems

        The acute toxicity of commercial OBDE for laboratory mammals is
    low. The substance is not irritant to the skin and gives only slight
    eye irritation in rabbits. In short-term toxicity studies (4-week and
    13-week), rats administered dietary levels of 100 mg/kg had increased
    liver weights and microscopic changes characterized by enlarged
    centrolobular and midzonal liver parenchymal cells containing granular
    structures. These liver changes were more severe at higher dose
    levels, i.e., 1000 and 10 000 mg/kg diet. In addition, hyperplasia of
    the thyroid was seen. Total bromine content in the tissues increased
    during the study and decreased slowly during a recovery period. The
    liver changes were reversible. In an inhalation study with micronized
    dust of OBDE (8 h/day for 14 consecutive days), no effects were
    observed with exposure to 1.2 mg/m3, but a level of 12 mg/m3 caused
    the liver changes described in the oral studies.

        In rats, commercial OBDE at relatively low doses increased
    cytochrome P450 and induced hepatic microsomal enzymes, such as
    UDP-glucuronyl transferase and benz[a]pyrene hydroxylase. Commercial
    OBDE induced a porphyrinogenic effect in cultures of chick embryo
    liver cells.

        OBDE was tested for teratogenic potential in rats; at high dose
    levels (25.0 and 50.0 mg/kg body weight), resorptions, or delayed
    ossification of different bones and fetal malformations were observed.
    The malformations observed with doses of 25 mg/kg body weight and
    higher were most likely associated with maternal toxicity. These
    changes were not seen at dose levels of 15.0 mg/kg body weight or
    less. In rabbits, there was no evidence for teratogenic activity, but
    fetotoxicity was seen at a maternally toxic dose level of 15 mg/kg
    body weight. Teratogenicity studies showed a no-effect level of
    2.5 mg/kg body weight.

        In 28-day and 90-day rat studies, 100 mg OBDE per kg diet
    (equivalent to 5 mg/kg body weight) induced minimal effects in the
    liver. No no-effect level was established.

        Results of the mutagenicity tests including an unscheduled DNA
    assay,  in vitro microbial assays, and an assay for sister chromatid
    exchange with Chinese hamster ovary cells were all negative.

        No long-term/carcinogenicity test results are available.

    1.1.7  Effects on humans

        No data are available.

    1.1.8  Effects on other organisms in the laboratory and field

        Minimal data are available.

    1.2  Conclusions

    1.2.1  OBDE

        Commercial OBDE is a mixture of hexa-, bepta-, octa-, and
    nonabromodiphenyl ether, all of which persist in the environment,
    largely bound to sediment.

        OBDE is widely incorporated in polymers as an additive flame
    retardant. Contact of the general population is with products made
    from these polymers. Exposure by extraction from polymers is unlikely.

        The acute toxicity of OBDE is low. There is no information on
    uptake and loss in mammals. OBDE is not teratogenic or mutagenic.
    Long-term toxicity and carcinogenicity studies are not available.

        Several components of commercial OBDE have been identified in
    human adipose tissue. The acute risk for the general population is
    likely to be low. Risk assessment of long-term exposure is not
    possible, because of the lack of relevant toxicity studies.

        No information is available to draw conclusions on occupational
    exposure to, or effects of, OBDE.

        Limited information is available on the toxicity of OBDE for
    organisms in the environment. Components of the commercial OBDE
    mixture with lower levels of bromination may bioaccumulate in
    organisms.

    1.2.2  Breakdown products

        Formation of PBDF, and to some extent PBDD, may occur when OBDE,
    or products containing it, are heated to 400-800 °C. The possible
    hazards associated with this have to be addressed.

        Exposure of the general population to PBDF impurities in
    flame-retarded polymers is unlikely to be significant. Properly
    controlled incineration should not lead to the emission of significant
    quantities of brominated dioxins and -furans. Any uncontrolled
    combustion of products containing commercial OBDE can lead to the
    generation of unquantified amounts of PBDF/PBDD. The significance of
    this for both humans and the environment will be addressed in a future
    EHC on PBDF/PBDD.

    1.3  Recommendations

    1.3.1  General

    *   Best available techniques should be used in the manufacture of
        commercial OBDE, to minimize levels of hexa- and lower brominated
        congeners, because of their bioaccumulation potential in the
        environment.

    *   Workers involved in the manufacture of OBDE, and products
        containing the compound, should be protected from exposure using
        appropriate industrial hygiene measures, monitoring of
        occupational exposure, and engineering controls.

    *   Environmental exposure should be minimized through the appropriate
        treatment of effluents and emissions in industries using the
        compound or products. Disposal of industrial wastes and consumer
        products should be controlled to minimize environmental
        contamination with this persistent material and its breakdown
        products.

    *   Incineration of materials, flame retarded with OBDE, should only
        be in properly constituted incinerators running under consistently
        optimal conditions. Burning by any other means may lead to
        production of PBDF and/or PBDD.

    1.3.2  Further studies

        Because the present toxicological database is inadequate to
    evaluate the hazards of commercial OBDE for humans and the
    environment, and, to support its use, the following studies should be
    carried out:

    *   Investigations on the bioavailability and ecotoxicity of
        sediment-bound components of commercial OBDE using the relevant
        organisms

    *   Extended monitoring of environmental levels of components of
        commercial OBDE

    *   Long-term toxicity and carcinogenicity studies of commercial OBDE

    *   Monitoring of occupational exposure to commercial OBDE

    *   Further investigations on the generation of PBDF under real fire
        conditions

    *   Further studies on environmental biodegradation and
        photodegradation in compartments other than water

    *   Investigation of possible methods and consequences of recycling of
        OBDE-containing polymers

    *   Validation of analytical methods for OBDE in various matrices

    *   Investigations on the possibility of migration from different
        types of polymers.

    2.  IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, ANALYTICAL METHODS

    2.1  Identity

    Chemical structure:

    CHEMICAL STRUCTURE 4

    Chemical formula:             C12H2Br8O

    Relative molecular mass:      801.47

    Common names:                 octabromodiphenyl ether (OBDE)
                                  octabromodiphenyl oxide

    CAS registry number:          32536-52-0

    EINECS number:                2510879

    MITI number:                  3-3716

    CAS name:                     1, 1'-oxy(bis)-octabromo-benzene

    Synonyms:                     octabromodiphenyl ether; benzene,
                                  1,1'-oxy-bis-,octabromo-phenyl
                                  ether

        Based on the chemical structure, there are 12 possible isomers of
    octabromodiphenyl ether.

        From: IRPTC (1988); US EPA (1984); Ethyl Corp. (1992b).

    2.1.1  Technical product

    Trade names:                  Bromkal 79-8 DE; DE-79TM; FR 143;
                                  Tardex 80; FR 1208; Adine 404;
                                  Saytex 111

        The commercial product is a mixture of polybrominated diphenyl
    ethers with the following typical composition (see Table 1):

             0-0.7%               decabromodiphenyl ether
          9.5-11.3%               nonabromodiphenyl ether
         31.3-35.3%               octabromodiphenyl ether
         43.7-44.5%               heptabromodiphenyl ether
         10.5-12.0%               hexabromo- and pentabromodiphenyl ether.

        Commercial OBDE has also been reported to be a mixture of 4%
    hexabromo-, 62% hepta-, and 34% octabromodiphenyl ether (De Kok et
    al., 1979).

    2.2  Physical and chemical properties

        Commercial products based on OBDE are off-white powders with a
    faint odour, and a bromine content of 79-81%. In case of fire, and, in
    the presence of fuels, hydrogen bromide and/or bromine may be
    liberated (Kopp, 1990).

    Melting point:                200 (167-257) °C, Ethyl Corp. (1992b);
                                  79-87 °C; 75-125 °C, Kopp (1990); and
                                  170-220 °C, De Kok et al. (1979)

    Vapour pressure:              < 10-7 mmHg at 25 °C

    Solubility at 25 °C in g/litre:
       water                      <1
       methanol                   2(7)
       methylene chloride         110
       toluene                    190 (353)
       benzene                    200
       styrene                    250
       methyl ethyl ketone        40
       acetone                    20 (122)

        (From: Great Lakes Chemical Corporation, 1987, 1990a)

    Specific gravity:              2.76 (2.63)

        (From: US EPA, 1989, 1986)

         n-Octanol/water partition
        coefficient (log Pow):     5.5; 8.35-8.90

        (From: Watanabe & Tatsukawa, 1990; Ethyl Corporation, 1992b).

    2.3  Analytical methods

        No specific data are available (see General Introduction section
    2.1 and Table 2).

    3.  SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE

    3.1  Natural occurrence

        Octabromodiphenyl ether has not been reported to occur naturally
    (see General Introduction, section 1.1).

    3.2  Anthropogenic sources

    3.2.1  Production levels and processes

        Octabromodiphenyl ether is synthesized by treating diphenyl ether
    with 8 equivalents of Br2 in the presence of Al2Cl6/A12Br6, first
    at 35 °C and then at 120 °C (US EPA, 1986). No data are available on
    production levels.

        The annual consumption of OBDE in Japan was 150 tonnes in 1983,
    and 1000 tonnes in 1987, mainly used in the preparation of ABS
    (Watanabe, 1987; Watanabe et al., 1987b). Consumption in Germany was
    600-800 tonnes/year in plastics in 1988 (CEM, 1989). Estimation of
    total use of octabromodiphenyl ether in the Netherlands in 1988 was
    600-800 tonnes.

        The actual worldwide consumption of OBDE per year is 6000 tonnes
    (Arias, 1992).

    3.2.2  Uses

        The high bromine content and its broad melting range make OBDE the
    material of choice for a large variety of thermoplastics. Its use is
    recommended for injection mouldings, especially when high surface
    quality is desirable. Applications: ABS, nylon, high impact
    polystyrene, low density polyethylene, polypropylene random copolymer
    (Flick, 1986). It is also used in adhesives and coatings.

        The major use of OBDE is in computer and business equipment
    cabinets (Personal communication, McAllister).

    4.  ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION

    4.1  Biotransformation

        No data are available.

    4.2  Abiotic degradation

    4.2.1  Pyrolysis of octabromodiphenyl ether

        Pyrolysis of octabromodiphenyl ether (OBDE) at 630 °C, in air,
    resulted in approximately 96% decomposition leading to the formation
    of polybrominated benzenes (PBBz) and about 5% of PBDF and PBDD,
    mainly two pentabromodibenzodioxins and a hexabromodibenzofuran. Small
    amounts of tri- to heptabromo-dibenzodioxins and tetra- to
    heptabromodibenzofurans were present (Buser, 1986).

    4.2.2  Pyrolysis studies with polymers containing octabromodiphenyl
           ether

        Pyrolysis studies were conducted on ABS containing OBDE (15%) and
    antimony trioxide (6%) at 600 °C (Neupert et al., 1989). Brominated
    dibenzofurans and brominated dibenzodioxins were identified in the
    pyrolysis residues, however, the brominated dibenzodioxins and
    2,3,7,8-TeBDF were present in very low quantities.

        The pyrolysis of Cycolac, flame retarded with OBDE in combination
    with antimony trioxide, gave high levels of brominated dibenzodioxins
    and dibenzofurans and significant levels (9.3 mg/kg) of
    2,3,7,8-isomers at 600 °C. Pyrolysis temperatures were 200, 250, and
    600 °C during 30 min. The total PBDF were 110.8, 666, and 1631 mg/kg,
    respectively. The values for PBDD were 1.75, 0.75, and 31.5 mg/kg,
    respectively (Fresenius Institute, 1990).

    4.2.3  Behaviour of octabromodiphenyl ether during processing

        BFRIP designed an experiment to investigate the behaviour of OBDE
    in ABS under controlled moulding or extrusion conditions. The polymer
    system ABS/OBDE was operated under different conditions (Table 25).
    After moulding, all the samples were analysed for brominated
    dibenzodioxins and dibenzofurans. With the exception of a single
    sample, brominated dibenzodioxins were not identified in any of the
    samples. In this sample, the 2,3,7,8-brominated dibenzofurans were
    seen only at very low concentrations (Table 26). The data show that
    processing of the resin systems under normal conditions (225 °C; 1-min
    cycle) resulted in no change in composition from that of the base
    resin formulation (BFRIP, 1990; McAllister et al., 1990).

        Table 25.  Moulding study with ABS/OBDE system at different processing temperaturesa
                                                                                             

    Polymer/FR          Severity                           Conditions
                                                                                             

    ABS/OBDE            normal                             225 °C, 1 min cycle
                        abusive                            245 °C, 10 min cycle

    ABS/OBDE            acrylonitrile-butadiene-           79.8%
                        styrene/OBDE +                     16.0%
                        antimony trioxide                  4.2%
                                                                                             

    aFrom:  McAllister et al. (1990).

    
        Craig et al. (1989) measured the PBDF and PBDD contents of pre-
    and post-extruded Cycolac resin treated with OBDE and antimony
    trioxide. Two samples were tested at extrusion temperatures around
    220 °C. PBDF levels varied from one another by a factor of 4 in the
    pre-extrusion samples and by a factor of 2 in the post-extrusion
    samples. The higher levels of total PBDF were 38 300 µg/kg in the
    pre-extruded and 84 500 µg/kg in the post-extruded resins. PBDD was
    not detected in the pre-extruded resin, but, in one post-extruded
    sample, it was found at a level of 112 µg/kg. The fumes emitted during
    extrusion were also analysed and a level of 1850 µg/kg was found. PBDD
    was found in a concentration of 0.54 µg/kg. (Fume data expressed as
    µg/kg of extruded resin).

    4.3  Bioaccumulation

        A single study on a mixture of PBDE including HxBDE to DeBDE
    indicated little bioaccumulation in carp with a bio-concentration
    factor of < 4 after 8 weeks of exposure (CBC, 1982).

    4.4  Ultimate fate following use

        For the ultimate fate of OBDE in the environment see General
    Introduction, section 6.1.

        Table 26.  Comparison of Triangle Laboratories Inc. (TLI) (Research Triangle
               Park) and US EPA Laboratory (Las Vegas) results on moulded polymer
               samples containing various flame retardants. (All concentrations
               are in mg/kg)a
                                                                               

    ABS with octabromodiphenyl ether
                                                                               

                        Normal 1222-16-4           Abusive 1222-16-5
                                                                               

    Compound            TLI          US            TLI          US
                                     EPAc                       EPA
                                                                               

    1,2,3,7,8-PeBDD     < 0.002                    0.02
    2,3,7,8-TeBDF       < 0.002                    0.004
    Total TeBDD         < 0.001                    0.01
    Total PeBDD           0.03                   < 0.13
    Total TeBDF           0.003      0.003         0.17           0.16
    Total PeBDF           1.1        1.3        < 14.0           31.5
    Total HxBDF       < 135.0        2.2       < 118.0            9.1
    Total HpBDFb        < 6.6        0.6         < 2.9            0.7
    Total OBDFb        < 34.5        0.04       < 13.9            0.02
                                                                               

    a  From: BFRIP (1990). Values preceded by < are maximum possible. Analytical signals
       met identification criteria, but may include contribution from interferences.
       US EPA and TLI used different identification criteria resulting in differences
       in reported values.
    b  Concentration of HpBDF and OBDF from TLI are not validated because of lack of
       standards. Concentrations are reported for comparison only.
    c  Average of two analysis of same sample.

    
    5.  ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE

    5.1  Environmental levels

    5.1.1  Water

        In Japan, OBDE was not detected in 75 water samples (limit of
    determination 0.1 µg/litre) in 1987 and was not detected in 147 water
    samples collected at 49 areas (limit of determination, 0.07 µg/litre)
    in 1988-89 (Environment Agency Japan, 1989, 1991).

    5.1.2  Aquatic sediments

        In 1987, environmental surveys were conducted concerning OBDE in
    bottom sediment. OBDE was detected in 3 out of 51 samples at
    concentrations ranging from 8 to 21 µg/kg in 1987 (limit of
    determination 7 µg/kg dry weight) and was detected in 3 out of 135
    samples, collected at 45 areas, at concentrations ranging from 15 to
    22 µg/kg dry weight (limit of determination 5 µg/kg) in 1988-89
    (Environment Agency Japan, 1989, 1991).

    5.1.3  Aquatic and terrestrial organisms

        In Japan, OBDE was not detected in 75 fish samples in 1987 and was
    not found in 144 fish samples collected in 48 areas in 1988-89 (limit
    of determination 5 µg/kg wet weight (Environment Agency Japan, 1989,
    1991).

    5.2  Exposure of the general population

        In the USA, Cramer et al. (1990a,b) studied the presence of
    PBDD/PBDF in human adipose tissue samples of the fiscal year 1987
    (National Human Adipose Tissue Survey). The samples were derived from
    865 specimen combined to form 48 composite analogues. The composite
    design was based on 9 census divisions and 3 age groups. The analysis
    was carried out using HRGC/HRMS to determine PBDD/PBDF. No PBDF/PBDD
    was found (limits of determination, 10-40 ng/kg, depending on
    congeners). Identification of the PBDE was based on comparison of full
    scan mass spectra of the samples with the available standards,
    application of SIM techniques to compare theoretical ion ratios with
    observed ion ratios for characteristic ions, and measurement of
    fragment losses from the molecular ion clusters. Preliminary evidence
    for the presence of OBDE was found (frequency, 60%) with an estimated
    concentration range of ND-8000 ng OBDE/kg (Cramer et al., 1990a,b;
    Stanley et al., 1991).

    5.3  Occupational exposure during manufacture, formulation, or use

        No data are available.

    6.  EFFECTS ON LABORATORY MAMMALS AND  IN VITRO TEST SYSTEMS

    6.1  Single exposure

    6.1.1  Oral: Rat

        The acute oral LD50 in the rat is >28 g/kg body weight (Kalk,
    1982); >5 g/kg body weight (Kopp, 1990; Great Lakes Chemical
    Corporation, 1990a).

        Male Charles River CD rats were administered commercial OBDE,
    suspended in corn oil, by intubation, at doses of 50, 500, or
    5000 mg/kg body weight. The observation period was 14 days. The rats
    showed normal weight gain and no animals died (Great Lakes Chem Corp.,
    1987; 1990a).

    6.1.2  Dermal: Rabbit

        Commercial OBDE was applied to the clipped, abraded, or intact
    skin of male and female albino rabbits at concentrations of 200 or
    2000 mg/kg body weight for 24 h. During the observation period of 14
    days, none of the rabbits died and all had normal weight gain. The
    dermal LD50 for rabbits is >2 g/kg body weight (Great Lakes Chemical
    Corporation, 1987, 1990a).

    6.1.3  Inhalation: Rat

        The inhalation LC50 of Saytex 111 in rats was > 50 mg/litre (US
    EPA, 1986).

        Male and female Charles River CD rats were exposed for 1 h to
    concentrations of commercial OBDE in air of 2 or 60 mg/litre. The
    physical nature of the substance precluded administration at higher
    levels than 60 mg/litre. Rats exposed to 2 and 60 mg/litre had
    decreased motor activity, erythema, and eye squint, during exposure.
    The animals exposed to 60 mg/litre also had tachypnea. During the
    14-day observation period, the animals appeared normal, and exhibited
    normal body weight gain, except for one rat at the highest dose level,
    which showed salivation on days 5 and 7 of the observation period
    (Great Lakes Chemical Corporation, 1987) (no further details).

    6.2  Short-term exposure

    6.2.1  Oral: Rat

        Charles River CD rats were fed commercial OBDE at daily, dietary
    dose levels of 0, 100, or 1000 mg/kg for 28 days. There were 10 male
    and 10 female rats in each dose group. No changes in appearance,
    behaviour, mortality, feed consumption, or body weight gain were
    observed. Results of haematology, blood chemistry, and urinalysis were
    similar to those in the controls. Absolute and relative liver weights
    were significantly increased in female rats given 100 mg/kg and in
    rats of both sexes given 1000 mg/kg diet. Other increases in organ
    weights were not considered compound-related. No gross pathological
    lesions were noted in rats in any of the groups. Compound-related
    histopathological liver lesions were observed in both treated groups

    of rats. They consisted of enlarged centrolobular and midzonal liver
    parenchymal cells in which the cytoplasm had large areas of finely
    granular structures containing eosinophilic "round bodies". These
    changes occurred more frequently and with greater severity in the male
    animals. Their incidence and severity were dose-related. Rats given
    1000 mg/kg had a slight to moderate hyperplasia of the thyroid, but it
    was not clear whether this was compound-related. Dose-related
    increases in total bromine levels of the liver were noted in both
    males and females and ranged from about 6 to 137 times the levels
    found in controls (Great Lakes Chemical Corporation, 1987).

        Another 28-day feeding study was carried out on 10 male and 10
    female Charles River CD rats per group, which were administered a diet
    containing 100, 1000, or 10000 mg commercial OBDE/kg. The control
    group consisted of 35 male and 35 female rats from the 90-day feeding
    study, described below. At the end of the study, 5 rats of each
    sex/group were sacrificed and the remaining 5 animals/sex per group
    were maintained on normal diets for 4 weeks (recovery period). No
    changes in appearance, behaviour, or mortality were observed. Food
    consumption and body weight gain were slightly higher in the control
    group. Haematology values were normal, but serum urea nitrogen levels
    were slightly elevated in some of the rats given 10 000 mg/kg diet. An
    increase in absolute and relative liver weights was observed in some
    of the rats given 1000 and 10 000 mg/kg. At necropsy, the livers of
    some animals in the 10 000 mg/kg group showed accentuated lobulization
    and discoloration. The livers of rats from all 3 dose levels showed
    enlargement of the centrolobular and midzonal hepatocytes, the
    cytoplasm of which had large areas of finely granular appearance and
    frequently contained eosinophilic "round bodies". In the 10 000 mg/kg
    group, vacuolization of hepatocytes and necrosis of scattered
    individual hepatocytes were seen. In all 3 treated groups, the liver
    lesions were less severe after the 4-week recovery period than during
    the administration of the compound. A dose-related increase in liver
    total bromine content was seen in rats in all treated groups after 4
    weeks of treatment, but these total bromine levels decreased rapidly
    in the recovery period. Only in the rats receiving the lowest dose
    level did the liver total bromine concentration approach control
    levels after a 4-week withdrawal period (Great Lakes Chemical
    Corporation, 1987).

        Charles River CD rats were fed commercial OBDE at dietary levels
    of 0, 100, 1000, or 10 000 mg/kg for up to 13 weeks. There were 35
    male and 35 female rats in each dose group. Behaviour, appearance,
    body weight, food consumption, haematology, blood chemistry, and
    urinalysis were studied after 1 and 2 months, and, at the end of the
    study, in groups of 5 rats/sex per group. The remaining 20 rats per
    group were used to study the recovery and 5 rats/sex per group were
    sacrificed after 13 and 21 weeks and 6 months after withdrawal. During
    the study, a few rats out of each group died, but without any
    dose-relationship, the majority of these deaths occurring after the
    collection of blood.

        In the 100 mg/kg diet group, the only effect that was seen was an
    increase in absolute and relative liver weights. Microscopic changes
    were seen in 4 out of 10 rats, and were typified by granular
    cytoplasmic changes, Liver total bromine contents increased during the
    13-week treatment, but decreased during the recovery period.

        In the 1000 mg/kg group, a decrease in body weight gain was
    observed, but haematology, blood chemistry, and urinalysis results
    were comparable with the controls. Increases in absolute and relative
    liver and thyroid weights were observed, but these effects were not
    seen in the animals sacrificed during the recovery period. Microscopic
    lesions were seen in the cytoplasm of the centrolobular and midzonal
    hepatocytes and included vacuolization, and hyaline intracytoplasmic
    inclusions. A hyperplastic nodule was found, after 6 months
    withdrawal, in one rat each from the 1000 and 10 000 mg/kg groups.

        In the 10 000 mg/kg group, a decrease in body weight gain was
    observed, even during the withdrawal period. Decreases in haemoglobin,
    haematocrit, and erythrocyte counts were also observed. One female
    animal had hypochromia, polychromia, and anisocytosis of the
    erythrocytes. Glucose levels in the blood were slightly lower than in
    the controls. Orange colouration of the urine was observed during
    weeks 13-39. A significant increase in absolute and relative liver,
    kidney, and thyroid weights was observed. At autopsy, there was
    accentuated lobulation and yellowish mottling of the livers and
    brownish discoloration of the liver and kidneys. After one year of
    recovery, no such gross changes were observed. Histopathologically,
    the liver changes consisted of granular cytoplasmic changes,
    cytoplasmic vacuolization (possibly representing fatty degeneration),
    necrosis of scattered parenchymal cells or of centrolobular cells,
    centrolobular fibrosis, and pigmented Kupfer cells. In the kidneys,
    the changes were characterized by the occurrence of small to moderate
    numbers of cortical regenerative tubules. One rat had a severe tubular
    nephrosis. Cellular changes in the thyroid were probably
    compound-related. During the recovery period, the histological changes
    decreased in severity and frequency.

        The total bromine content of the liver increased during the 13
    weeks of treatment and decreased during the recovery period, but
    remained higher (not significantly) than the control values after one
    year (Great Lakes Chemical Corporation, 1987).

    6.2.2  Inhalation: Rat

        Charles River CD rats were exposed (whole-body) to a micronized
    dust of commercial OBDE, introduced into inhalation chambers at
    nominal concentrations of 1.2, 12, 120, and 1200 mg/m3 for 8 h/day on
    14 consecutive days. Actual airborne dust concentrations were 15-45%
    of the nominal values. It was not possible to measure the extent of
    oral intake of the substance. There were 5 male and 5 female rats in

    each dose group and in the controls. No animals died during the test
    period nor were there any changes in appearance or general behaviour
    in the 1.2 and 12 mg/m3 groups. By the end of the 8-h exposure
    period, all animals in the 1200 mg/m3 group and part of the
    120 mg/m3 group exhibited a fast breathing pattern, which had
    disappeared by the morning following exposure. Food consumption, body
    weight gain, haematology, blood chemistry, and urinalysis in all of
    the dose groups were normal. The total bromine concentrations in the
    lung, liver, and fat were significantly higher than in the controls.
    At autopsy, the average total bromine concentrations in the lung and
    fat were about 1.5-12.5 times higher than in the liver. The relative
    liver weights of the animals in the 12, 120, and 1200 mg/m3 dose
    groups were significantly increased in a dose-related manner. These
    changes were accompanied by histopathological lesions consisting of
    focal to multifocal cytoplasmic enlargement of the hepatocytes, and
    focal acidophilic degeneration of individual, and small groups of,
    liver cells. At the 2 highest dose levels, the enlargement of the
    hepatocytes was multifocal to diffuse in distribution and small to
    large areas had necrosis in the centrolobular regions of the affected
    liver lobules, especially in the 1200 mg/m3 group. No other
    compound-related effects were observed (Great Lakes Chemical
    Corporation, 1987).

    6.3  Long-term exposure

        No data are available.

    6.4  Skin and eye irritation; sensitization

    6.4.1  Skin irritation

        Commercial OBDE was applied to the clipped and occluded intact, or
    abraded, skin of male and female albino rabbits at a dose of 500 mg.
    After 24 h, the skin was washed and examined for irritation. The
    examination was repeated after 72 h. One rabbit had slight erythema at
    72 h; the remaining rabbits did not have skin changes. It was
    concluded that OBDE is not a primary skin irritant (Great Lakes
    Chemical Corporation, 1987).

    6.4.2  Eye irritation

        Single applications of 100 mg commercial OBDE were made into the
    conjunctival sac of the eye of 3 male and 3 female New Zealand white
    rabbits. Examinations were made at 24, 48, and 72 h, and 7 days. A
    slight discharge was noted from the eyes of 2 rabbits at 24 h and a
    slight redness was noted in the eye of one rabbit at 48 h. No ocular
    irritation or corneal damage (sodium fluorescein and UVR were used)
    was observed (Great Lakes Chemical Corporation, 1987).

    6.5  Teratogenicity, reproductive toxicity, and embryotoxicity

    6.5.1  Teratogenicity

    6.5.1.1  Oral: Rat

        In a range-finding study, female rats (number not specified) were
    dosed daily, by gavage, from days 6 to 15 of gestation with 2.5, 10.0,
    15.0, 25.0, or 50.0 mg commercial OBDE (DE-79)/kg body weight. All
    animals survived until gestation day 20, when they were sacrificed. At
    25.0 mg/kg, increased serum bromine levels were observed. Mean
    maternal body weight gain was reduced in the 50.0 mg/kg group during
    gestation. Increased numbers of late resorptions and significantly
    reduced mean fetal weights were observed at the highest dose level.
    The cholesterol level was slightly increased in the dams given
    50.0 mg/kg. No compound-related microscopic findings were observed in
    the liver and kidneys of the mothers. No compound-related effects were
    observed at 15.0 mg/kg or lower. The malformations and developmental
    variations observed in the 50.0 mg/kg group were associated with
    maternal toxicity. Fetal anasarca and bent limb bones were observed at
    this dose level. Mean fetal body weight and increased post
    implantation loss due to !ate resorptions was also observed at this
    level, but the losses were not statistically significant, compared
    with the controls. Reduced ossification of the skull, various
    unossified bones, and two instances of bent ribs were noted at this
    dose level, and were probably secondary to maternal toxicity (Great
    Lakes Chemical Corporation, 1987) (abstract).

        Four groups of 25 pregnant Charles-River Crb:COBS CD (SD) BR rats
    were administered corn-oil suspensions of Saytex 111, by gavage, at
    doses of 0, 2.5, 10.0, or 25 mg/kg body weight per day on days 6-15 of
    gestation. The dams were sacrificed on day 20 of gestation and the
    fetuses were examined for gross visceral and skeletal abnormalities.
    The substance was more toxic to the conceptus than to the dam. At
    25.0 mg/kg, dose-dependant effects on the conceptus were observed.
    These included reduced average fetal body weight, increased
    embryo/fetal deaths (resorptions), fetal malformations, such as
    enlarged heart, rear limb malformation, and delayed skeletal
    ossification. At 10 mg/kg, the only observed effect was a
    statistically insignificant reduction in average fetal body weight (US
    EPA, 1986).

    6.5.1.2  Oral: Rabbit

        Groups of 26 inseminated adult New Zealand White rabbits (weight
    3.5-4.5 kg) were treated with 0 (corn oil), 2.0, 5.0, or 15 mg Saytex
    111/kg body weight per day, by gavage, on days 7-19 of gestation.
    Saytex 111 was a mixture containing; 0.2% PeBDE, 8.6% HxBDE, 45.0%
    HpBDE, 33.5% OBDE, 11.2% NBDE, and 1.4% DeBDE. Body weight gain was

    recorded on gestation days 0, 7, 10, 13, 16, 20, and 28. In addition,
    maternal liver, kidneys, and gravid uterine weights were measured at
    the time of hysterectomy. The offspring were examined on day 28 of
    gestation. A statistically significant increase in liver weight and a
    decrease in body weight gain were observed in the 15 mg/kg group.
    There was no statistically significant deviation in maternal
    mortality, number of pregnancies, number of litters with viable pups,
    corpora lutea/dam, implantations/dam, live fetuses/litter, percentage
    of resorptions, and fetal body weight. Slight fetal toxicity was
    observed in the 15 mg/kg group, as evidenced by a significant increase
    in delayed ossification of the sternebrae. There was an increase in
    the incidence of retrocaval ureter in the 5 and 15 mg/kg group and
    fused sternebrae in the 5 mg/kg group. These increases were not dose
    related. It was concluded by the authors that there was no evidence
    for teratogenic activity but that there was slight letotoxicity at
    maternally toxic dose levels, e.g., 15 mg/kg body weight (Breslin et
    al., 1989).

    6.6  Mutagenicity and related end-points

    6.6.1  DNA damage

        An unscheduled DNA synthesis (UDS) assay, a test to induce DNA
    damage followed by repair in mammalian cells, was carried out with
    monolayers of WI-38 human fibroblast cells, which were exposed to
    commercial OBDE in the presence of radiolabelled thymidine. OBDE was
    tested at 5 concentrations ranging from 60 to 300 µg/ml. UDS was not
    induced by OBDE either in the presence or in the absence of a
    metabolic activation system (Great Lakes Chemical Corporation, 1987).

    6.6.2  Mutation

        Commercial OBDE was examined for mutagenic activity at a number of
    concentrations in  in vitro microbial assays using  Salmonella
     typhimurium and Saccharomyces cerevisiae with, and without, liver
    microsomal enzyme preparations from Aroclor-induced rats. The results
    of these tests were all negative (Great Lakes Chemical Corporation,
    1987) (no details).

    6.6.3  Chromosomal effects

        In an assay for sister chromatid exchanges, Chinese hamster ovary
    cells were exposed to concentrations of commercial OBDE of 7.5, 25,
    75, 250, or 750 µg/ml (in DMSO), for 2 h, in the presence, or absence,
    of a metabolic activation system. The exposure period was followed by
    a 24-h expression period. No statistically significant increases in
    the number of exchanges per chromosome or the number of exchanges per
    cell were seen at any of the levels tested (Great Lakes Chemical
    Corporation, 1987).

    6.7  Carcinogenicity

        No data are available.

    6.8  Other special studies

    6.8.1  Liver

        Commercial OBDE in corn oil was administered by gavage to six male
    Sprague-Dawley rats (200-250 g) for 90 days. When extensive induction
    was revealed at all the original doses of 6.25, 12.5, and 25 µmol/kg
    per day, the study was repeated at doses of 0.78, 1.56, and
    3.13 µmol/kg per day. OBDE did not cause induction of NADPH cytochrome
    c reductase and cytochrome P450 at the lower doses. However, a dose of
    0.78/µmol/kg per day caused increases in both  O-ethyl-
     O-p-nitrophenyl phenyl-phosphonothioate (EPN) detoxification and
     p-nitroanisole demethylation; larger increases were seen with
    increasing dose levels. After a 30-day recovery period, evidence of
    the maintenance of an induced state was seen only in animals receiving
    3.13 µmol/kg per day. These elevations were still observable 60 days
    after the last dose. No histological liver abnormalities were observed
    in rats treated with 3.13 µmol/kg body weight or less (Carlson,
    1980b).

        In another study on male rats (200-250g) administered commercial
    OBDE, by gavage, at 0.1 mmol/kg per day in corn oil for 14 days, the
    above increase in enzyme activity was accompanied by an increase in
    activity of UDP-glucuronyl transferase and benzo[a]pyrene hydroxylase
    24 h after the seventh dose (Carlson, 1980a). Measurements made on
    days 30 and 60 of recovery after 90 days exposure showed that the
    indicators of induced xenobiotic metabolism returned slowly to control
    values.

        Koster et al. (1980) found a strong porphyrinogenic effect in
    cultures of chick embryo liver cells at concentrations of 10 µg
    commercial OBDE (in DMSO)/ml medium, with, and without, pretreatment
    of ß-napthoflavone, an inducer of P450, P448, and delta-aminolevulinic
    acid synthethase. The effect was determined semiquantitatively with
    fluorescence microscopy, 24 h after addition of the flame retardant.

    6.9  Appraisal

        In 28-day and 90-day rat studies, 100 mg OBDE per kg diet
    (equivalent to 5 mg/kg body weight) induced minimal effects in the
    liver. No no-effect level was established. In a 14-day inhalation
    study with micronized dust of OBDE, no effects were found with
    exposure to 12 mg/m3. Teratogenicity studies showed a no-effect level
    of 2.5 mg/kg body weight.

        At the highest reported value of OBDE of 8000 ng/kg, from the
    Human Adipose Tissue Sample Study, assuming 15% adipose tissue in the
    adult male, a "stored" dose of 1.2 µg/kg can be calculated. Assuming
    1% of the administered dose was absorbed, this would extrapolate to a
    total dose of 120 µg/kg. With the further assumption that the total
    exposure occurred over one year, a daily dose of 0.38 µg/kg per day
    can be calculated. This dose is approximately 4 orders of magnitude
    below the most sensitive endpoint in mammalian toxicity testing on
    OBDE (NOEL = 2.5 mg/kg body weight in a teratology study).

    HEPTABROMODIPHENYL ETHER

    1.  SUMMARY, EVALUATION, CONCLUSIONS AND RECOMMENDATIONS

        Heptabromodiphenyl ether is not manufactured or used.

        There is no database on pure HpBDE on which to make an evaluation.

        No data are available on the following topics:

    *   Kinetics and metabolism in laboratory animals and humans

    *   Effects on humans

    *   Effects on other organisms in the laboratory and field

    *   Previous evaluations by international bodies.

        Because HpBDE is the major component of commercial
    octabromodiphenyl ether, the summary, evaluation, conclusions, and
    recommendations on commercial OBDE, are relevant to "commercial"
    HpBDE.

    2.  IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, AND ANALYTICAL METHODS

    2.1  Identity

    Chemical structure:

    CHEMICAL STRUCTURE 5

    Chemical formula:             C12 H3 Br7 O

    Relative molecular mass:      722.3

    CAS registry number:          68928-80-3

    CAS name:                     1,1'-oxy-bis(heptabromobenzene)

    Common name:                  heptabromodiphenyl
                                  ether (HpBDE)

        From: US EPA (1986).


        On the basis of the chemical structure, there are 24 possible
    isomers of heptabromodiphenyl ether.

    2.2  Physical and chemical properties

    Melting  point:               70-150 °C
                                  (decomposition > 232 °C)

    Density:                      2.6 at 20 °C

    Vapour pressure:              <13.3 Pa at 20 °C

     n-Octanol/water partition
    coefficient (log Pow):        not available

        From: US EPA (1986).

    2.3  Analytical methods

        No specific data are available (See General Introduction, section
    2.1 and Table 2).

    3.  SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE

    3.1  Natural occurrence

        Heptabromodiphenyl ether has not been reported to occur naturally
    (see General Introduction, section 1.1).

    3.2  Anthropogenic sources

    3.2.1  Production levels and processes

        Heptabromodiphenyl ether is not produced commercially or used, but
    octabromodiphenyl ether contains approximately 44% HpBDE (see General
    Introduction, Table 1).

    4.  ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION

        A single study on mixed PBDE ranging from HxBDE and DeBDE
    indicated lime bioaccumulation in carp with a bioconcentration factor
    of <4, after 8 weeks of exposure (CBC, 1982).

    5.  ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE

        Cramer et al. (1990a,b) studied the presence of PBDD/PBDF in human
    adipose tissue samples in the USA in the fiscal year 1987 (National
    Human Adipose Tissue Survey). The samples were derived from 865
    specimens combined to form 48 composite analogues. The composite
    design was based on 9 census divisions and 3 age groups. The analysis
    was carried out using HRGC/HRMS to determine PBDD/PBDF. No PBDF/PBDD
    were found, the limit of determination ranging from 10 to 40 ng/kg,
    depending on the congeners. Identification of the PBDE was based on
    comparison of full scan mass spectra of the samples with the available
    standards, the application of SIM techniques to compare theoretical
    ion ratios with observed ion ratios for characteristic ions, and the
    measurement of fragment losses from the molecular ion clusters.
    Preliminary evidence for the presence of heptabromodiphenyl ether was
    found at a frequency of 100%, with an estimated concentration range of
    1-2000 ng HpBDE/kg (Cramer et al., 1990a,b; Stanley et al., 1991).

    6.  EFFECTS ON LABORATORY MAMMALS AND IN VITRO TEST SYSTEMS

    No data are available on the following topics:

    *   Short-term exposure

    *   Long-term exposure

    *   Reproductive toxicity, embryotoxicity, and teratogenicity

    *   Mutagenicity

    *   Carcinogenicity.

    6.1  Single exposure

        The acute oral LD50 for the rat is > 5 g/kg and the dermal LD50
    for the rabbit, >2 g/kg body weight (Kopp, 1990).

    6.2  Skin and eye irritation; sensitization

        The substance is not irritant for either the skin or eyes (Kopp,
    1990).

    HEXABROMODIPHENYL ETHER

    1.  SUMMARY, EVALUATION, CONCLUSIONS AND RECOMMENDATIONS

        Hexabromodiphenyl ether is not manufactured or used, but occurs as
    a contaminant of commercial brominated diphenyl ethers. Such levels of
    hexabromodiphenyl ether should be minimized to avoid contamination of
    the environment and exposure of humans.

        There is no database on which to make an evaluation.

        No data are available on the following topics:

    *   Effects on laboratory mammals and  in vitro test systems

    *   Effects on humans

    *   Effects on other organisms in the laboratory and field

    *   Previous evaluations by international bodies.

    2.  IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, ANALYTICAL METHODS

    2.1  Identity

    Chemical structure:

    CHEMICAL STRUCTURE 6

    Chemical formula:             C12 H4 Br6O

    Relative molecular mass:      643.62

    CAS registry number:          36483-60-0

    CAS name:                     1.1'-oxy-bis-hexabromobenzene

    Common names:                 hexabromodiphenyl ether (HxBDE)
                                  hexabromodiphenyl oxide

        From: (US EPA, 1984, 1986).

        On the basis of the chemical structure, there are of 42 possible
    isomers of hexabromodiphenyl ether.

    2.1.1  Technical product

    Trade names:                  BR 33N

    2.2  Physical and chemical properties

    Vapour pressure:              0.95-0.99 kPa at 25 °C

     n-Octanol/water partition
    coefficient (log Pow):        6.86-7.92

        From: Pijnenburg & Everts (1991).

    2.3  Analytical methods

        No specific data are available (see General Introduction, section
    2.1 and Table 2).

    3.  SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE

    3.1  Natural occurrence

        Hexabromodiphenyl ether has not been reported to occur naturally
    (see General Introduction, section 1.1).

    3.2  Anthropogenic sources

        As far as is known, hexabromodiphenyl ether has not been produced
    commercially or used, but it is a component of TeBDE, PeBDE, and OBDE
    at concentrations ranging from 4 to 12% (see General Introduction,
    Table 1).

    3.3  Uses

        Total use of penta- and hexabromodiphenyl ethers in the Netherlands in
    1988 was estimated to be 350 tonnes (Anon, 1989).

    4.  ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION

        A single study on a mixture of PBDE, ranging between HxBDE and
    DeBDE, indicated little bioaccumulation in carp with a
    bioconcentration factor of < 4, after 8 weeks of exposure (CBC,
    1982).

    5.  ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE

    5.1  Levels in the environment

    5.1.1  Water

        In Japan, HxBDE was not detected in 75 samples of water in 1987 or
    in 150 samples collected in 50 areas in 1988-89 (in both cases the
    limit of determination was 0.04 µg/litre) (Environment Agency Japan,
    1989, 1991).

    5.1.2  Aquatic sediments

        Marine, estuarine, and river sediment samples were collected at
    different places in Japan in 1981-83 and analysed for HxBDE. Five out
    of 15 samples contained 9-26 µg/kg (Watanabe, 1987; Watanabe et al.,
    1987b).

        In 1987, environmental surveys were conducted on HxBDE levels in
    sediment in Japan. HxBDE was detected in 4 out of 69 samples at
    concentrations ranging from 7 to 77 µg/kg dry weight (limit of
    determination 5.1 µg/kg dry weight) in 1987, and, in 4 out of 141
    samples collected in 47 areas in 1988-89, at concentrations ranging
    from 4.5 to 18 µg/kg dry weight (limit of determination 3.5 µg/kg dry
    weight) (Environment Agency Japan, 1989, 1991).

    5.1.3  Aquatic and terrestrial organisms

        Mussel and a few species of fish (mullet, goby, and Japanese sea
    bass) were collected from different seashores in Japan from 1981 to
    1985. Other fish species were purchased at a wholesale commercial
    source in Osaka Prefecture in 1981. HxBDE could not be detected
    (<0.2 µg/kg wet weight) in any of the 5 mussel samples or in the 12
    fish samples (Watanabe, 1987; Watanabe et al., 1987b).

        In 1987, environmental surveys were conducted on HxBDE levels in
    fish in Japan. HxBDE was detected in 5 out of 75 fish samples at
    concentrations ranging from 3.8 to 14 µg/kg wet weight in 1987 and was
    detected in 5 out of 144 samples collected at 48 areas at
    concentrations ranging from 2 to 6 µg/kg wet weight in 1988-89 (limit
    of determination 2 µg/kg wet weight) (Environ. Agency Japan, 1989,
    1991).

    5.2  General population exposure

        In the USA, Cramer et al. (1990a,b) studied the levels of
    PBDD/PBDF in human adipose tissue samples in 1987 (National Human
    Adipose Tissue Survey). The samples were derived from 865 specimens
    combined to form 48 composite analogues. The composite design was
    based on 9 census divisions and 3 age groups. The analysis was carried
    out using HRGC/HRMS to determine PBDD/PBDF. No PBDF/PBDD were found,
    the limit of determination ranging from 10 to 40 ng/kg, depending on
    the congeners. Identification of the PBDE was based on comparison of
    full scan mass spectra of the samples with the available standards,
    application of SIM techniques to compare theoretical ion ratios with
    observed ion ratios, for characteristic ions, and measurement of
    fragment losses from the molecular ion clusters. Preliminary evidence
    for the presence of HxBDE was found at a frequency of 72%, in an
    estimated concentration range of ND to 1000 ng HxBDE/kg (Cramer et
    al., 1990a,b; Stanley et al., 1991).

    6.  KINETICS AND METABOLISM IN LABORATORY ANIMALS AND HUMANS

        The half-life of pentabromodiphenyl ether (Bromkal 70) was
    investigated in the perirenal fat of groups of 3 male and 3 female
    Wistar rats (weight 160-180 g), following a single oral dose of
    300 mg/kg body weight in peanut oil. The groups were killed on days 1,
    2, 3, 4, and 7 and then weekly for 10 weeks. Perirenal fat was
    collected and analysed. Half-lives in male and female rats of 2
    hexabromodiphenyl ethers (HxBDE(1) and HxBDE(2)) were: for female
    rats, 44.6 (37.4-51.9) days and 90.0 (78.7-103.6) days, and, for male
    rats, 55.1 (48.4-61.7) and 119.1 (102.8-136.1) days, respectively (Von
    Meyerinck et al., 1990).

    PENTABROMODIPHENYL ETHER

    1.  SUMMARY, EVALUATION, CONCLUSIONS AND RECOMMENDATIONS

        Pentabromodiphenyl ether is not manufactured or used.

        No data are available on the following topics:

    *   Effects on humans

    *   Effects on other organisms in the laboratory and field

    *   Previous evaluations by other international bodies.

    1.1  Summary and evaluation

    1.1.1  Identity, physical and chemical properties

        Commercial pentabromodiphenyl ether (PeBDE) is a mixture of
    tetra-, penta-, and hexabromodiphenyl ethers. It contains
    approximately 50-60% PeBDE and 24-38% TeBDE. On the basis of the
    chemical structure, there are 46 possible isomers of PeBDE and 42
    possible isomers of TeBDE. The commercial products seem to contain 3
    main components, i.e., 2,2',4,4',5-PeBDE, 2,2',4,4'-TeBDE, and an
    unidentified congener containing 5 bromines.

        The melting point is -7 to -3 °C and the boiling point, above
    200 °C. The vapour pressure is low: <10-7 mmHg and the solubility
    in water is negligible. The n-octanol/water partition coefficient
    (log Pow) >6.

    1.1.2  Production and uses

        PeBDE is used as an additive in epoxy resins, phenol resins,
    polyesters and polyurethane, and textiles. Worldwide consumption is
    approximately 4000 tonnes per year. It is one of the major commercial
    brominated diphenyl ether flame retardants.

    1.1.3  Environmental transport, distribution, and transformation

        Components of commercial PeBDE have been found in biota, sediment,
    and sewage sludge samples. Commercial PeBDE EHC 162: Brominated
    diphenyl ethers components are likely to be persistent and
    bioaccumulate. A bioconcentration factor of over 10 000 has been found
    in carp for PeBDE.

        Pyrolysis studies with commercial PeBDE showed that PBDF and PBDD
    are formed. The optimal temperature for the formation of the PBDF and
    PBDD was between 700-800 °C. When PeBDE was pyrolysed in the absence
    of oxygen, polybromobenzenes, polybromophenols, and PBDF were formed.

    1.1.4  Environmental levels and human exposure

        Sediment samples taken from rivers and estuaries in Japan showed
    levels ranging from no PeBDE (<2 µg/kg) up to 28 µg/kg dry weight. In
    Sweden, the concentrations in sediment samples of certain rivers were
    up to 1200 µg 2,2',4,4,'5-PeBDE/kg. Sewage sludge, analysed in Sweden
    also contained this PeBDE.

        In mussel and fish collected from different seashores in Japan in
    the period 1981-85, concentrations of 0.4 and 2.8 µg PeBDE/kg wet
    weight were found in 2 out of 5 mussel samples. No PeBDE was detected
    in fish (limit of determination < 0.2 µg/kg). Concentrations of
    1.9-22 µg/kg, on a fresh weight basis, were reported in liver samples
    from cod from the North Sea. In Sweden, concentrations of between 7.2
    and 64 µg 2,2',4,4',5-PeBDE/kg fat were found in freshwater whitefish
    and herring collected at different places.

        Pooled blubber of ringed seal and of grey seal collected in Sweden
    in 1979-85 contained average concentrations of 1.7 µg and 40 µg
    2,2',4'4',5-PeBDE/kg fat, respectively.

        Pooled samples of muscle of rabbits, moose, and suet samples of
    reindeer collected in 1985-86 in Sweden contained < 0.3 µg, 0.64 µg,
    and 0.26 µg 2,2',4,4',5-PeBDE/kg fat, respectively.

        Muscle samples of osprey, collected in Sweden in 1982-86,
    contained an average concentration of 140 µg 2,2',4,4',5-PeBDE/kg fat.

        The levels of 2 PeBDE isomers in guillemot eggs from the Baltic
    have increased by one order of magnitude during the last decades. The
    levels of these isomers in pike from a lake in Southern Sweden also
    showed an increase (by a factor of about 4).

        Baltic sediments representing different sampling years also
    indicate a considerable increase during the last decade.

        There is minimal information on human exposure, but a rough
    estimate of exposure of the Swedish population through fish
    consumption would suggest an intake of 0.1 µg PeBDE/person per day.

    1.1.5  Kinetics and metabolism in laboratory animals and humans

        The half-life of PeBDE has only been investigated in the perirenal
    fat in rats. The average half-life was between 25 and 47 days,
    depending on the sex of the animal and the type of isomer determined.

    1.1.6  Effects on laboratory mammals and  in vitro test systems

        The acute oral toxicity of commercial PeBDE is low in rats; the
    dermal toxicity in rabbits is also low. Short-term inhalation exposure
    in rats and the application of PeBDE to the conjunctival sac in
    rabbits caused only mild, transient effects.

        In short-term toxicity studies on rats (4-week and 13-week),
    dietary concentrations of 100 mg/kg increased liver weights and caused
    slight histological alterations. Changes consisted of the enlargement
    of hepatic parenchymal cells, which had a granular appearance and
    contained eosinophilic "round bodies". Dose-related increases in total
    bromine content in the liver occurred and levels remained elevated for
    as long as 24 weeks. A mild degree of thyroid hyperplasia, which was
    reversible, was observed.

        Hepatic enzyme induction and increases in cytochrome P450 c
    occurred after oral administration of daily doses of PeBDE as low as
    0.78 µmol/kg body weight. The results of tests for teratogenicity and
    mutagenicity were negative.

        No long-term/carcinogenicity studies have been reported.

    1.1.7  Effects on humans

        No data are available.

    1.1.8  Effects on other organisms in the laboratory and field

        Minimal data are available.

    1.2  Conclusions

    1.2.1  PeBDE

        Commercial PeBDE (a mixture of 24-38% tetra-, 50-60% penta-, and
    4-8% hexabromodiphenyl ether) is persistent and accumulates in
    organisms in the environment.

        Commercial PeBDE is widely used, incorporated in polymers as an
    additive flame retardant. Contact of the general population is with
    products made from these polymers. Exposure by extraction from
    polymers is unlikely. Human exposure to PeBDE via the food chain may
    occur, since the substance has been detected in organisms in the
    environment that are human food items, such as fish, shellfish, etc.
    In fish and birds from Sweden, increasing levels have been measured
    over the last 2 decades.

        The acute toxicity of commercial PeBDE is low. There is no
    information on uptake and loss in mammals. Reproduction, long-term
    toxicity, and carcinogenicity studies are not available.

        The risk to the general population cannot be determined from the
    available data.

        No information is available to draw conclusions on occupational
    exposure levels or the effects of commercial PeBDE.

        Limited information is available on the toxicity of commercial
    PeBDE for organisms in the environment.

    1.2.2  Breakdown products

        PBDF and, to some extent, PBDD are formed when PeBDE (or products
    containing it) are heated to 400-800 °C. The possible hazards
    associated with this have to be addressed.

        Exposure of the general population to PBDF in polymers flame
    retarded with PeBDE is unlikely to be of significance. Properly
    controlled incineration does not lead to the emission of significant
    quantities of brominated dioxins and -furans. Any uncontrolled
    combustion of products containing PeBDE can lead to the generation of
    unquantified amounts of PBDF/PBDD. The significance of this for both
    humans and the environment will be addressed in a future EHC on
    PBDF/PBDD.

    1.3  Recommendations

    1.3.1  General

        Persistence in the environment and accumulation in organisms
    suggest that commercial PeBDE should not be used. However, if use
    continues, the following points should be taken into account:

    *   Workers involved in the manufacture of PeBDE and products
        containing the compound should be protected from exposure using
        appropriate industrial hygiene measures, the monitoring of
        occupational exposure, and engineering controls.

    *   Environmental exposure should be minimized through the appropriate
        treatment of effluents and emissions in industries using the
        compound or products. Disposal of industrial wastes and consumer
        products should be controlled to minimize environmental
        contamination with this persistent and accumulating material and
        its breakdown products.

    *   Incineration of materials flame retarded with PeBDE should only be
        carried out in properly constituted incinerators running
        consistently under optimal conditions. Burning by any other means
        will lead to production of toxic breakdown products.

    1.3.2  Further studies

    *   Continued monitoring of environmental levels is required.

    *   Methods for the determination of PeBDE in various matrices should
        be validated.

    *   Because the present toxicological database is inadequate to
        evaluate the hazards of commercial PeBDE for humans and the
        environment, and to support its use, the following studies should
        be done:

        -   additional toxicological, carcinogenicity, and
            ecotoxicological studies;

        -   further investigations on the generation of PBDF under real
            fire conditions;

        -   investigations on possible methods and consequences of
            recycling of PeBDE-containing polymers;

        -   studies on the possibilities of migration from flame-retarded
            products.

    2.  IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, ANALYTICAL METHODS

    2.1  Identity

    Chemical structure:

    CHEMICAL STRUCTURE 7

    Chemical formula:             C12H5Br5O

    Relative molecular mass:      564.75

    Common name:                  pentabromodiphenyl ether (PeBDE);
                                  pentabromodiphenyl oxide

    CAS registry number:          32534-81-9

    CAS name:                     1,1'-oxybis-pentabromo-benzene,
                                  benzene, 1,1'-oxybis-, pentabromo

        On the basis of the chemical structure, there are 46 possible
    isomers of pentabromodiphenyl ether.

        From: IRPTC (1988).

    2.1.1  Technical product

    Trade name                    DE 71; Bromkal 70-5 DE;
                                  FR 1205/1215;
                                  Bromkal 70; Bromkal G1;
                                  Pentabromprop;
                                  DE-60 F is a mixture of 85%
                                  PeBDE and 15% of an aromatic phosphate

        Commercial pentabromodiphenyl ether is a mixture of polybrominated
    diphenyl ethers with the following typical composition (see Table 1):
    0-1% tribromodiphenyl ether, 24-38% tetrabromodiphenyl ether, 50-62%
    pentabromodiphenyl ether, 4-8% hexabromodiphenyl ether (Arias, 1992).

        DE-71 is primarily a mixture of tetra-, penta-, and
    hexabromodiphenyl ethers containing low levels of tribromodiphenyl
    ether (< 1%) and heptabromodiphenyl ether (< 2%) (McAllister &
    Ariano, 1982). Pentabromprop is a mixture of 39% tetra-, 61% penta-,
    and 9% hexabromodiphenyl ethers. Bromkal 70-5 DE is a mixture of 34.2%
    tetra-, 59.8% penta-, 5.8% hexa-, and 0.2% heptabromodiphenyl ethers,
    but 41.7% tetra- and 45% pentabromodiphenyl ethers, and 7% of a second
    pentabromodiphenyl ether have also been reported (Nylund et al.,
    1992). Another manufacturer produces a mixture of 35% tetra-, 58%
    penta-, and 4% higher brominated diphenyl ethers under the name of
    Pentabromodiphenyl ether. Bromkal 70 is a mixture containing 36%
    tetrabromo- and 74% pentabromodiphenyl ether. The bromine contents of
    the mixtures range from 67 to 71.8% (De Kok et al., 1979). Bromkal
    70-5, a mixture of brominated diphenyl ethers containing 67-71%
    bromine, and an average of about 5 bromines per molecule, also
    contained various isomers of tri-, tetra-, penta-, and
    hexabromodiphenyl ethers. However, it is no longer produced
    commercially (McAllister, 1991).

        Sundström & Hutzinger (1976) identified 2,2',4,4'-tetra- and
    2,2',4,4',5,-PeBDE as the major components of Bromkal 70-5 DE.

    2.2  Physical and chemical properties

        Pentabromodiphenyl ether (PeBDE) is a clear, amber to pale yellow,
    highly viscous liquid, with an organic smell. Under conditions of
    fire, hydrogen bromide and/or bromine occur.

    Melting point                 -7 to -3 °Ca

    Boiling point                 > 300 °C (decomposition starts
                                  above 200 °C)

    Specific gravity              2.28 at 25 °C; 1.78 at 40 °C

    Vapour pressure               9.3 mmHg at 22 °Cb
                                  (6.26-6.66 Torr at 25 °C)

    Solubility                    Insoluble in water (9 × 10-7 mg/litre
                                  at 20 °C), methanol 10 g/litre at 25 °C,
                                  soluble in other organic solvents
                                  such as chloroform, benzene, toluene,
                                  acetone, carbon-tetrachloride, and
                                  methylene chloride

    Viscosity at 50 °C            1-6 Pa (150 000 cp at 25 °C;
                                  1500 cp at 60 °C)

     n-Octanol/water partition
    coefficient (log Pow)         6.64-6.97

        From: Great Lakes Chemical Corporation (undated a); Kalk (1982);
    Kopp (1990); US EPA (1989); Hallenbeck (1993); US Testing Comp.
    (1985).

    2.3  Analytical methods

        McAllister & Ariano (1982) developed a method for the
    determination of the arbitrarily defined "bromination level" of PeBDE
    (DE-71), both as the neat material and as a formulation in DE-60 F,
    and for the quantitative determination of aromatic phosphate ester in
    DE-60 F. The sample is dissolved in dibromomethane containing an
    internal standard and the components separated by gas chromatography.

        A multiresidue method has been developed for the determination of
    PBDE residues in environmental samples (see General Introduction,
    section 2.1 and Table 2).

    3.  SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE

    3.1  Natural occurrence

        Pentabromodiphenyl ether has not been reported to occur naturally
    (see General Introduction, section 1.1).

    3.2  Anthropogenic sources

    3.2.1  Production levels and processes

        Pentabromodiphenyl ether is synthesized by treating diphenyl ether
    with 5 equivalents of Br2 at 30-65 °C in the presence of powdered
    iron (US EPA, 1986).

        The actual worldwide consumption of PeBDE per year is 4000 tonnes.
    In the Federal Republic of Germany, in 1988, the approximate level of
    use in plastics was 200-400 tonnes/year. The total use of penta- and
    hexabromodiphenyl ethers in the Netherlands in 1988 was estimated to
    be 350 tonnes (Anon., 1989b).

        Production levels are not available.

    3.2.2  Uses

        PeBDE is used as an additive in epoxy resins, phenol resins,
    unsaturated polyesters, polyurethane flexible, and textiles.

    4.  ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION

    4.1  Pyrolysis

        PeBDE (Bromkal 70, 70-5 DE, G1) were heated in a quartz tube at
    700, 800, or 900 °C and the concentrations of PBDD and PBDF
    determined. Monobromo- to pentabromodibenzofurans, as well as
    monobromo- to tetrabromodioxins, were found in yields of up to 90% in
    all 3 Bromkal samples. The optimal temperatures of formation were
    between 700 and 800 °C (Thoma et al., 1987a).

        Bromkal 70-5-DE was pyrolysed at 600, 700, 800, and 900 °C, in the
    absence of oxygen, in a SGE pyrojector and the residues analysed by
    GC/MS in an on-line operation. The pyrolysis of Bromkal 70-5-DE
    yielded polybromobenzenes (PBBz), polybromophenois (PBP), and
    brominated dibenzofurans. Because this pyrolysis is performed in a
    pyrojector with a helium current, incorporation of oxygen is
    impossible, consequently dioxins do not form (Thoma & Hutzinger, 1987,
    1989).

    4.2  Workplace exposure studies

        In the processing of PBT, finished with pentabromodiphenyl ether
    at 300 °C, PBDF were found in both the air at the workplace and the
    machine extractor. PBDF were also found in air samples taken from a
    vessel in which the granulate was stored. Since the bulk of the PBDF
    formed during processing remain in the product, it can be assumed that
    parts made from the polymers, such as computer casings, television
    sets, etc., are contaminated with PBDF (CEM, 1989).

    4.3  Bioaccumulation

        Carp exposed for 8 weeks to commercial pentabromodiphenyl ether at
    10 or 100 µg/litre showed bioconcentration factors of more than 10 000
    (CBC, 1982).

    4.4  Ultimate fate following use

        For the ultimate fate of PeBDE following use see section 6.1 of
    the General Introduction.

    5.  ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE

    5.1  Levels in the environment

    5.1.1  Sediment and sewage sludge

        Sediment samples were taken from the rivers near the centre of
    Osaka City and marine sediments, from different estuaries in Japan and
    from Osaka Bay, during the period 1981-83. No PeBDE was found
    (<2 µg/kg dry weight in 9 estuarine or marine sediment samples. PeBDE
    was present in 5 out of 6 river sediment samples at concentrations of
    9-28 µg/kg on a dry weight basis (Watanabe, 1987; Watanabe et al.,
    1987b).

        Organic extracts, made from coastal sediments, collected offshore
    from Barcelona, were analysed for the presence of organohalogenated
    chemicals. A diversity of organohalogenated compounds were found,
    among them PeBDE (Fernandez et al., 1992).

        Sellström et al. (1990a,b) analysed sediment samples, taken
    upstream and downstream from a factory, for the presence of
    tetrabromobisphenol-A and derivatives. Both tetrabromobisphenol A and
    2,2',4,4',5-pentabromodiphenyl ether were found. The levels found in
    upstream and downstream sediments were 8.2 and 1200 µg/kg (ign loss),
    respectively.

        A laminated sediment core collected in the southern part of the
    Baltic Proper (Bornholm Deep) was analysed for 2,2',4,4',5-PeBDE. The
    core was cut into 5 mm slices down to 50 mm depth and in 10 mm slices
    from 50 to 90 mm depth. The concentration of PeBDE at a depth of 5 mm
    was 0.98 µg/kg IG and decreased more or less gradually in the deeper
    layers to approximately 0.05 µg/kg at a depth of 40 mm. Below this
    depth, levels were mostly not detectable (Nylund et al., 1992).

        Sellström et al. (1990a,b) analysed sewage sludge and found 19 µg
    2,2',4,4',5-pentabromodiphenyl ether/kg ign loss.

        Two sewage samples were collected from a Swedish treatment plant
    (Gothenburg) in September 1988 anti analysed for PBDE. One homogenate
    was composed of samples (40 g/day) taken over a 32-day period with
    little rain. Another homogenate was composed of samples (100 g/day)
    taken during a rainy period of 7 days. Both TeBDE and PeBDE were
    found. The concentration of 2,2',4,4',5-PeBDE was 19 µg/kg;
    concentrations of PeBDE of unknown structures were 3.4 and 3.7 µg/kg
    and total PeBDE, 37-38 µg/kg IG (Nylund et al., 1992).

    5.1.2  Fish and shellfish

        Mussels and some species of fish, e.g., mullet, goby, and Japanese
    sea bass, were collected from different seashores in Japan from 1981
    to 1985. Other fish species were purchased from a commercial wholesale
    source in Osaka Prefecture in 1981. In 2 out of 5 mussel samples,
    levels of 0.4 and 2.8 µg PeBDE/kg wet weight were found. In 12 fish
    samples, no PeBDE (< 0.2 µg/kg wet weight) was found (Watanabe, 1987;
    Watanabe et al., 1987b).

        2,2',4,4',5'-Pentabromodiphenyl ether (PeBDE) was found in cod
    liver (2 samples from each region) from the southern, central, and
    northern regions of the North Sea, in 1982-87. Levels were 3.6 and
    22.0 µg/kg; 4.9 and 7.2 µg/kg; and 1.9 and 6.5 µg/kg, respectively, on
    a product basis (De Boer, 1989).

        A multiresidue analytical method was applied to pooled muscle
    samples of 35 freshwater whitefish  (Coregonus sp.), 15 samples of
    arctic char  (Salvelinus alpinus), and a total of 260 samples of
    herring  (Clupea harengus), collected at different places in Sweden
    during the period 1986-87. The average concentrations of
    2,2',4,4',5-pentabromodiphenyl ether were 7.2, 64, and 9.8-46 µg/kg
    lipid, respectively (Jansson et al., 1993).

        Samples of bream, pike, perch, and trout from Sweden were shown to
    contain 2,2',4,4',5-PeBDE in concentrations of 2.3-2.4 µg/kg,
    60-1100 µg/kg, 380-9400 µg/kg, and 130-590 µg/kg lipid, respectively.
    Another PeBDE isomer of unknown structure was also found in all fish
    samples at concentrations of 11-37 µg/kg, 25-640 µg/kg,
    230-3500 µg/kg, and 33-150 µg/kg lipid, respectively. The samples
    represent both background and industrialized areas (Sellström et al.,
    1993a).

        A study of TeBDE and PeBDE in banked samples of pike from a lake
    in Southern Sweden revealed concentrations increasing from 40 µg/kg
    lipid in 1974 to 180/µg/kg lipid in 1991 (Sellström et al., 1993b).

        Kruger (1988) sampled 40 freshwater fish of various species from
    the waters of North-Rhine Westfalia in Germany and found PBDE in
    concentrations ranging from 18 to 983 µg/kg fat, measured as Bromkal
    70-5DE. Concentrations in 6 sea fish from the Baltic Sea ranged from
    12 to 57 µg PBDE/kg fat and those in 11 fish from the North Sea, from
    1 to 120 µg/kg fat, measured as Bromkal 70-5DE.

    5.1.3  Aquatic mammals

        Pooled samples of blubber of 7 ringed seals  (Pusa hispida),
    collected in 1981, and of 8 grey seals  (Halichoerus grypus),
    collected in 1979-85, in Sweden were analysed using a multiresidue
    analytical method. The average concentrations of 2,2',4,4',5-
    pentabromodiphenyl ether were 1.7 and 40 µg/kg lipid, respectively
    (Jansson et al., 1993).

    5.1.4  Terrestrial mammals

        Pooled samples of muscle of 15 rabbits  (Orytolagus cuniculus),
    13 samples of moose  (Alces alces), and 31 suet samples of reindeer,
    collected in the period 1985-86, in Sweden, were analysed using a
    multiresidue method. The average concentrations for rabbits, moose,
    and reindeer, were < 0.3, 0.64, and 0.26 µg 2,2',4,4',5-penta-
    bromodiphenyl ether/kg lipid, respectively (Jansson et al., 1993).

        Concentrations of 10 µg PBDE/kg fat, measured as Bromkal 70-DE,
    were detected in samples from 8 seals from Spitzbergen (Kruger, 1988).

        PBDE, measured as Bromkal 70-DE, was detected in 4 samples of
    cow's milk at concentrations ranging from 2.5 to 4.5 µg/kg fat
    (Kruger, 1988).

    5.1.5  Birds

        Pooled samples of muscle of 35 osprey  (Pandion haliaetus),
    collected in Sweden in the period 1982-86, were analysed using a
    multiresidue method, for 2,2',4,4',5-pentabromodiphenyl ether. The
    average concentration was 140 µg/kg lipid (Jansson et al., 1993).

        Newborn starlings from different places in Sweden have been shown
    to contain 2.34.2 µg 2,2',4,4',5-PeBDE/kg lipid and an unidentified
    PeBDE at 0.62-1.1 µg/kg lipid (Sellström et al., 1993a). The same
    authors reported concentrations of the same two PeBDE isomers in
    guillemot eggs from the Baltic Sea, caught during the period 1970-89
    (see Table 27).

    Table 27.  Average PeBDE concentrations µg/kg lipid) in guillemot
               eggs from the Baltic Seaa
                                                                    

    Sampling year      2,2',4,4',5-PeBDE               PeBDE
                                                (unknown structure)
                                                                    

    1970                      24                         4.2
    1974                      48                         8.5
    1975                      33                         4.6
    1976                     130                        32
    1979                     130                        37
    1982                     200                        44
    1983                     210                        49
    1986                     260                        48
    1987                     160                        40
    1989                     240                        61
                                                                    

    a  From: Sellstrom et al.(1993a),

    5.2  General population

        Samples of human milk from 26 women in North Rhine Westfalia,
    Germany, were analysed for PBDE, measured as Bromkal 70-DE.
    Concentrations in the milk from 25 of the women ranged from 0.62 to
    11.1 µg/kg fat. In one Chinese woman, a level of 50 µg/kg fat was
    found (Kruger, 1988).

        In Sweden, the major human exposure is via fish-related food and
    the levels of PeBDE in fish may be used to estimate this exposure
    route. Normal fish intake in Sweden is about 30 g/day, and, if herring
    is used as a model fish, this will give an estimate of intake of about
    0.1 µg PeBDE/person per day (Personal Communication, Jansson).

    6.  KINETICS AND METABOLISM IN LABORATORY ANIMALS AND HUMANS

        The half-life of pentabromodiphenyl ether (Bromkal 70) in
    perirenal fat was investigated in groups of 3 male and 3 female Wistar
    rats (weight 160-180 g) following a single oral dose of 300 mg/kg body
    weight in peanut oil. Animals from the groups were killed on days 1,
    2, 3, 4, and 7 and then at weekly intervals for 10 weeks. The
    perirenal fat was collected and analysed. The half-lives of 2 PeBDE
    isomers, following extraction and separation with HPLC (containing
    also tetrabromo- and hexabromodiphenyl ethers), are summarized in
    Table 28 (Von Meyerinck et al., 1990).

    Table 28.  Half-lives of PeBDE in male and female ratsa
                                                                         

    PBDE        Half-lives in female rats    Half-lives in male rats
                         in days                     in days
                                                                         

    PeBDE(1)b       47.4 (42.5-52.4)            36.8 (33.7-40.0)
    PeBDE(2)b       25.4 (22.6-28.4)            24.9 (22.6-27.1)
                                                                         

    a  From: von Meyerinck et al. (1990).
    b  (1) and (2) means two different isomars. Confidence interval,
       P=0.05.


    7.  EFFECTS ON LABORATORY MAMMALS AND  IN VITRO TEST SYSTEMS

    7.1  Single exposures

    7.1.1  Oral

        Groups of 5 male, albino Charles River CD rats were administered
    (by gavage) 50, 500, or 5000 mg commercial PeBDE (in corn oil)/kg body
    weight and observed for 14 days. The rats receiving 50 and 500 mg/kg
    survived and exhibited normal body weight gain. Four out of 5 rats
    dosed with 5000 mg/kg died within 5 days. The remaining rats survived
    and showed normal growth (Great Lakes Chemical Corporation,
    undated a).

        Groups of 5 male and 5 female Wistar rats were administered 2400,
    4800, 6048, 7621, or 9600 mg commercial PeBDE/kg body weight. The
    substance was given by gavage as an 80% w/v suspension in maize oil
    after which the rats were observed for 44 days. The acute oral LD50
    was 7400 mg/kg for males and 5800 mg/kg body weight for females. The

    symptoms seen were decrease in growth, diarrhoea, piloerection,
    reduced activity, clonic persistent tremors of the fore limbs, and red
    staining around eyes and nose. A continual chewing movement of the
    jaws was also seen. Post-mortem examination revealed pale (mottled),
    enlarged, necrotic livers and multiple small ulcerations of the
    gastric mucosa (Great Lakes Chemical Corporation undated a).

    7.1.2  Dermal

        Commercial PeBDE was applied to the clipped intact or abraded skin
    of groups of 2 male and 2 female New Zealand white rabbits at doses of
    200 or 2000 mg/kg body weight, for 24 h, under an occlusive dressing.
    The rabbits were observed for 14 days. No animals died during the
    observation period.

        At 200 and 2000 mg/kg, normal body weight gain or only a slight
    decrease in growth was seen (Great Lakes Chemical Corporation,
    undated a).

    7.1.3  Inhalation

        The inhalation LC50 for the rat is >200 mg/litre (Kopp, 1990).
    Groups of 10 male and 10 female Charles River CD rats were exposed for
    1 h to an aerosol mist of commercial PeBDE mixed with corn oil at
    concentrations of 2 or 200 mg/litre of air and subsequently observed
    for 14 days. No rats died during the study. The rats exposed to
    2 mg/litre exhibited increased and then decreased motor activity,
    erythema, and eye squint during the exposure and for the following
    24 h. After 24 h, and up to the end of the study, the animals appeared
    normal. During exposure to 200 mg/litre, the same signs were observed
    but also lacrimation, salivation, and tachypnoea. At 24 h and 48 h, 2
    rats exhibited nasal congestion and one rat showed respiratory
    congestion after 72 h. From day 4 to day 14, the animals appeared
    normal and showed normal body weight gain (Great Lakes Chemical
    Corporation, undated a).

    7.2  Short-term exposure

        Charles River CD rats were fed dietary levels of 0, 100, or
    1000 mg commercial PeBDE (dissolved in corn oil)/kg daily for 28 days.
    There were 10 male and 10 female animals in each group. No changes
    were noted in behaviour, appearance, food consumption, or body weight
    gain. Absolute and relative liver weights were significantly increased
    in female rats fed with 100 mg/kg and in male and female rats fed with
    1000 mg/kg. The liver lesions were more prevalent in male rats and
    increased with dose. A significant decrease in the relative weights of
    the pituitary and adrenal glands was found at the highest dose level.
    No compound-related, gross pathological lesions were noted.
    Microscopically, enlargement of the centrolobular and midzonal liver
    parenchyma cells was seen, and the cytoplasm included areas with a
    finely granular appearance; eosinophilic "round bodies" in enlarged

    hepatocytes were seen in the animals at both dose levels. Several rats
    from both the 100 mg and the 1000 mg/kg groups had slight to moderate
    hyperplasia of the thyroid, but control animals also had thyroid
    glands that could be considered hyperplastic. In thyroid glands
    designated as hyperplastic, most follicles were very small, devoid of
    colloid, and lined by basophilic columnar follicular epithelium.
    Whether these thyroid changes were compound-related is not clear.
    Dose-related increases in total bromide levels in liver tissues from
    the (pooled) treated rats were 6-12 times higher than those in the
    controls (Great Lakes Chemical Corporation, undated a).

        Commercial PeBDE (DE-71) was given in the diet to 3 groups of 30
    male and 30 female CD Sprague-Dawley rats. Dosage levels of 0, 2, 10,
    or 100 mg/kg per day were administered for 90 days. Ten animals per
    sex were sacrificed after 4 weeks and after 90 days, 5 animals were
    sacrificed after a 6-week recovery period, and 5 animals, after a
    24-week recovery period. No increased mortality or clinical effects
    were observed. Decrease in food consumption was seen in high-dose
    females and a decrease in body weight was observed in high-dose males
    and females. Haematology parameters and liver function were normal,
    but increased cholesterol values were observed for high-dose animals.
    Tri-iodothyronine (T3) levels were normal, but tetraiodothyronine (T4)
    levels were decreased (not dose-related) in the 10 mg and 100 mg/kg
    group; an increase in serum total bromide levels was observed in these
    2 groups after 4 and 13 weeks. Compound-related increases in liver and
    urine porphyrins were observed in the high-dose animals after 13
    weeks. Urine porphyrin levels were 13 times higher in females and up
    to 8 times higher in males and liver porphyrin levels were almost 400
    times higher than those of the controls. Compound-related increases in
    tissue total bromine levels were noted in all tissues for males and
    females at both the low- and high-dose levels (mid-dose levels not
    determined). During the recovery period, a slow decrease in the total
    bromine levels was noted, but, even after 24 weeks, the levels did not
    reach the control values, especially in the highest dose group.
    Relative liver weights in the 10 and 100 mg/kg groups were increased,
    but, during the recovery period, liver weights that were still higher
    after 6 weeks were normal after 24 weeks. Microscopic examination
    revealed hepatocytomegaly and thyroid hyperplasia. The thyroid
    hyperplasia was reversible in 24 weeks recovery period, but the liver
    still showed slight hepatocytomegaly in the 10 and 100 mg/kg group. At
    the lowest dose level (2 mg/kg), the only effect observed after 24
    weeks' recovery, i.e., liver cell degeneration and necrosis, was seen
    in females, but not in males (Great Lakes Chemical Corporation,
    undated a).

    7.3  Long-term exposure

        No data are available.

    7.4  Skin and eye irritation; sensitization

    7.4.1  Skin irritation

        Commercial PeBDE was applied, under occlusion, to the clipped
    intact or abraded skin of groups of 3 male and 3 female New Zealand
    white rabbits at a dose of 0.5 ml (approximately 1135 mg). After 24 h,
    the wrappings were removed and the backs of the rabbits washed and
    examined for signs of irritation. The examinations were repeated at
    72 h. At 24 and 72 h, no, or only very slight, erythema was noted. No
    oedema was seen (Great Lakes Chemical Corporation, undated a).

    7.4.2  Eye irritation

        A single application of 0.1 ml commercial PeBDE was instilled into
    the conjunctival sac of the eyes of 3 male, and 3 female, New Zealand
    white rabbits. Examinations were carried out at 24, 48, and 72 h, and
    at 7 days. At 24 h, all rabbits showed slight redness, slight
    chemosis, and slight discharge of the conjunctivae. These symptoms
    subsided during 7 days. At 7 days, slight alopecia around the eyelid
    was seen in 2 of the 6 animals. No irritation of the iris was
    observed. Examination at 72 h revealed slight evidence of corneal
    damage in one of the 6 animals (Great Lakes Chemical Corporation,
    undated a).

    7.5  Reproductive toxicity, embryotoxicity, and teratogenicity

        Pregnant female rats were given corn-oil suspensions of commercial
    PeBDE, by gavage, at dosages of 0, 10, 100, or 200 mg/kg body weight
    per day, on days 6-15 of gestation. The material was not teratogenic.
    The maternal no-effect level was 10 mg/kg and the embryo/fetal
    no-effect level was 100 mg/kg body weight. Inhibition of maternal body
    weight gain occurred at doses of 100 or 200 mg/kg. A slight,
    nonstatistically significant, reduction in average fetal body weight
    per litter was found at the highest dose level (BFRIP, 1990) (no
    further details).

    7.6  Mutagenicity and related endpoints

        Commercial PeBDE was examined for mutagenic activity at a number
    of concentrations in a series of  in vitro microbial assays using
     Salmonella typhimurium TA98, TA100, TA1535, and TA1537 and
     Saccharomyces cerevisae in the presence, and absence, of liver
    microsomal enzyme preparations from Aroclor-induced rats. A negative
    result was obtained with and without microsomal activation (Great
    Lakes Chemical Corporation, undated a).

    7.7  Carcinogenicity

        No data are available.

    7.8  Other special studies

        Commercial PeBDE in corn oil was administered, by gavage, to 6
    male Sprague-Dawley rats (200-250 g) for 90 days. When the original
    doses of 6.25, 12.5, and 25 µmol/kg per day revealed extensive
    induction, the study was repeated at doses of 0.78, 1.56, and
    3.13 µmol/kg per day. When the lower dose levels were tested, even the
    lowest dose of PeBDE (0.78 µmol/kg) caused increases in
     O-ethyl- O-p-nitrophenyl phenylphosphonothiate (EPN)
    detoxiFication,  p-nitroanisole demethylation, and NADPH cytochrome c
    reductase and cytochrome P450 activity. A clear dose-response
    relationship was found for EPN detoxification and  p-nitroanisole
    demethylation. When the animals were allowed a 30-day recovery period
    following the last (90th) dose, elevations in these two measurements
    were still observable at all doses, though increased NADPH cytochrome
    c reductase activity was found only at the highest dose. Within this
    period, the cytochrome P450 content had returned to normal. Even after
    60 days recovery, elevations were noted in EPN detoxification and
     p-nitroanisole demethylation at the 1.56 and 3.13 µmol/kg levels. No
    histological liver abnormalities were observed in rats treated with
    doses of 3.13 µmol/kg or less (Carlson, 1980b).

        In another study, rats (200-250g) were administered commercial
    PeBDE at 0.1 mmol/kg per day, in corn oil, by gavage, for 14 days. In
    addition to the above described effects on the enzymes, increases in
    the activities of UDP-glucuronyl-transferase and benzo[ a]pyrene-
    hydroxylase were found 24 h after the seventh dose (Carlson, 1980a).

        Von Meyerinck et al. (1990) studied the hepatic microsomal enzyme
    inducing potential of Bromkal 70 in Wistar rats. A series of dosing
    regimes was used, which varied from single oral doses of up to
    300 mg/kg body weight to 28 daily oral doses of 50 mg/kg body weight.
    In all cases, the vehicle was peanut oil (1 ml/kg), which was also
    administered to the vehicle control group. There were 3 male and 3
    female rats per group, except in the 28-day study in which 4 male and
    4 female rats were used. The treatments resulted in 31-53% increases
    in liver weight, 2.3-3.9-fold increases in cytochrome P450 c levels,
    up to 2-fold increases in benzphetamine N-demethylation activity, and
    2.2-5.3-fold increases in benzo( a)pyrene oxidation. Increases in
    ethoxyresorufin  O-deethylation activity ranged from not detectable
    to 0.35 nmol/min mg microsomal protein in control groups to between
    4.1 and 16.6 nmol/min mg microsomal protein in treatment groups. These
    activities were sex and dose dependent. The most sensitive parameter
    was ethoxyresorufin  O-deethylase induction, which showed no
    significant response in rats dosed once with 3 mg PeBDE/kg and killed
    3 days later.

        Commercial PeBDE (Bromkal 70-5 DE) showed the induction of
    ethoxyresorufin  O-deethylase activity in H-4-II E cells (Hanberg et
    al., 1991).

    TETRABROMODIPHENYL ETHER

    1.  SUMMARY, EVALUATION, CONCLUSIONS AND RECOMMENDATIONS

        Tetrabromodiphenyl ether is not manufactured or used.

        No data are available on the following topics:

    *   Effects on laboratory mammals and  in vitro test systems

    *   Effects on humans

    *   Effects on other organisms in the laboratory and field

    *   Previous evaluations by international bodies.

    1.1  Summary and evaluation

    1.1.1  Identity, physical and chemical properties

        Commercial tetrabromodiphenyl ether, consisted of 41% tetra-, 45%
    penta-, and 7% hexabromodiphenyl ethers and about 7% PBDE of unknown
    structure. On the basis of the chemical structure, there are 42
    possible isomers of tetrabromodiphenyl ether. Virtually no data are
    available on physical and chemical properties, except that the
     n-octanol/water partition coefficient (log Pow) is 5.87-6.16.

    1.1.2  Production and uses

        There is a report of the production (use) of about 1000 tonnes of
    TeBDE in Japan in 1987. There is no known current production under the
    name of tetrabromodiphenyl ether, but TeBDE is present in quantities
    of from 24 to 38% in commercial pentabromodiphenyl ether.

    1.1.3  Environmental transport, distribution, and transformation

        Components of commercial TeBDE have been found in biota, sediment,
    and sewage sludge samples. Commercial TeBDE components (containing
    approximately equal quantities of PeBDE) are likely to be persistent
    and to bioaccumulate.

        Pyrolysis studies with commercial TeBDE showed that PBDF and PBDD
    are formed at 800 °C. Higher PBDF and PBDD were not found.

    1.1.4  Environmental levels and human exposure

        TeBDE was found, in Japan, in river sediment at concentrations of
    12-31 µg/kg dry weight and, in Sweden, at concentrations of up to
    840 µg/kg ign. loss, respectively. TeBDE was also found in sewage
    sludge in Sweden, at a concentration of 15 µg/kg.

        Mussels and fish, collected at different places in Japan,
    contained TeBDE in concentrations ranging from < 0.1 to 14.6 µg
    2,2',4,4'-TeBDE/kg wet weight. In Sweden, different types of fish were
    collected from rivers and analysed for 2,2',4,4'-TeBDE. The mean
    concentrations ranged from ND (< 0.1 mg/kg) to 110 mg/kg fat. The
    analysis indicated that there was at least one local source of
    pollution in a certain river. Whitefish, arctic char, and herring,
    collected at different places in Sweden in 1986-87, contained
    concentrations of 15, 400, and 59-450 µg 2,2',4,4'-TeBDE/kg fat,
    respectively. Fish collected from rivers in Germany contained up to
    1 mg TeBDE/kg fat.

        In herring and in the liver of cod, collected in the southern,
    central, and northern North Sea, in the period 1983-89, a decreasing
    trend in the concentrations of TeBDE was found from the southern
    region to the northern region. In the herring, concentrations of
    8.4-100 µg 2,2',4,4'-TeBDE/kg, on a fat basis, were found.

        The muscle tissue of birds nesting and wintering in the Baltic
    Sea, the North Sea, and Spitzbergen, contained from 80 to 370 µg
    2,2',4,4'-TeBDE/kg, on a fat basis. Osprey collected in Sweden in the
    period 1982-86, contained average concentrations of 1800 µg/kg fat.

        Increasing trends in the concentrations of 2,2',4,4'-TeBDE have
    been indicated for Baltic sediments, freshwater fish, and sea bird
    eggs from Sweden.

        The blubber of seals collected in the Baltic Sea and Spitzbergen
    showed concentrations of 10-730 µg 2,2',4,4'-TeBDE/kg, on a fat basis.
    The chromatographic pattern of the PBDE was similar to that of Bromkal
    70-5. Pooled samples of the blubber of ringed seals and grey seals,
    collected in Sweden in 1979-85 showed concentrations of 47 µg and
    650 µg 2,2',4,4'-TeBDE/kg fat, respectively.

        Pooled muscle samples of terrestrial mammals, e.g., rabbits, moose
    and reindeer, collected in 1985-86 in Sweden, showed average
    concentrations of <2, 0.82, and 0.18 µg 2,2',4,4'-TeBDE/kg fat,
    respectively.

        Levels of 2.5-4.5 µg PBDE/kg fat, measured as Bromkal 70DE, were
    found in 4 samples of cow's milk in Germany. PBDE, as Bromkal 70DE,
    was found in the milk of 25 women in Germany at concentrations ranging
    from 0.62 to 11.1 µg/kg fat.

        A rough estimate of exposure via fish consumption among the
    Swedish population would suggest an intake of 0.3 µg TeBDE/ person per
    day.

    1.1.5  Effects on laboratory mammals and  in vitro test systems

        There are no data on TeBDE itself, but acute and short-term data
    are available for commercial PeBDE containing 41% TeBDE.

    1.1.6  Kinetics and metabolism in laboratory animals and humans

        Minimal data are available.

    1.1.7  Effects on humans

        No data are available.

    1.1.8  Effects on other organisms in the laboratory and field

        No data are available.

    1.2  Conclusions

    1.2.1  TeBDE

        Components of commercial TeBDE (a mixture of 41% 2,2',4,4'-tetra-;
    45% 2,2',4,4',5'-penta-; 7% hexa-, and 7-8% polybrominated diphenyl
    ethers with an unknown structure) are persistent and accumulate in
    organisms in the environment.

        TeBDE as a component of pentabromodiphenyl ether is widely
    incorporated in polymers as an additive flame retardant. Contact of
    the general population is with products made from these polymers.
    Exposure by extraction from polymers is unlikely. Human exposure to
    TeBDE, via the food chain, may occur, because the substance has been
    detected in organisms in the environment that are human food items,
    such as fish, shellfish, etc. In fish and birds from Sweden,
    increasing levels have been measured over the last two decades.

        There is a lack of information concerning short-, long-term
    toxicity/carcinogenicity, and reproduction studies. Furthermore,
    information on kinetics and metabolism in laboratory animals and
    humans is not available.

        The risk for the general population cannot be determined on the
    basis of available data.

        No information is available to draw conclusions on occupational
    exposure levels or the effects of TeBDE.

        No data are available on the toxicity of commercial TeBDE for
    organisms in the environment.

    1.2.2  Breakdown products

        PBDF and PBDD are formed when TeBDE are heated to 800 °C. The
    possible hazards associated with this have to be addressed.

        Exposure of the general population to PBDF in polymers, flame
    retarded with TeBDE, is unlikely to be of significance. Properly
    controlled incineration does not lead to the emission of significant
    quantities of brominated dioxins and furans. Any uncontrolled
    combustion of products containing TeBDE can lead to the generation of
    unquantified amounts of PBDF/PBDD. The significance of this for both
    humans and the environment will be addressed in a future EHC on
    PBDF/PBDD.

    1.3  Recommendations

    1.3.1  General

    Because of their persistence in the environment and accumulation in
    organisms, it is recommended that TeBDE should not be used. However,
    should use continue, the following points must be taken into account:

    *   Workers involved in the manufacture of TeBDE and products
        containing the compound should be protected from exposure using
        appropriate industrial hygiene measures, the monitoring of
        occupational exposure, and engineering controls.

    *   Environmental exposure should be minimized through the appropriate
        treatment of effluents and emissions in industries using the
        compound or products. Disposal of industrial wastes and consumer
        products should be controlled to minimize environmental
        contamination with this persistent and accumulating compound and
        its breakdown products.

    *   Incineration of materials, flame retarded with TeBDE, should only
        be carried out in properly constituted incinerators running under
        optimal conditions. Burning by any other means will lead to the
        production of furan breakdown products.

    1.3.2  Further studies

    *   Continued monitoring of environmental levels is required.

    *   Analytical methods for TeBDE in various matrices should be
        validated.

    *   Because the present toxicological data base is inadequate to
        evaluate the hazards of commercial TeBDE for humans and the
        environment, if use is continued, the following studies should be
        done:

        -   additional toxicological, carcinogenicity, and
            ecotoxicological studies;

        -   further investigations on the generation of PBDF under real
            fire conditions;

        -   investigation into possible methods and consequences of
            recycling of TeBDE-containing polymers;

        -   investigations of the possibility of migration from
            flame-retarded products.

    2.  IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, ANALYTICAL METHODS

    2.1  Identity

    Chemical structure:

    CHEMICAL STRUCTURE 8

    Chemical formula:             C12H6Br4O

    Relative molecular mass:      485.82

    Common names:                 tetrabromodiphenyl ether (TeBDE)
                                  tetrabromodiphenyl oxide

    CAS registry number:          40088-47-9

    CAS name:                     1.1'-oxybis-tetrabromo-benzene

        On the basis of the chemical structure, there are 42 possible
    isomers of tetrabromodiphenyl ether.

    2.2  Physical and chemical properties

        The technical product consist of 41.7% (41%) of
    2,2',4,4'-tetrabromodiphenyl ether, 44.4% (45%) 2,4,5,2',4'-
    pentabromo-diphenyl ether, 6% (7%) hexabromodiphenyl ether and
    7.6% PBDE of an unknown structure (see also pentabromodiphenyl ether
    and Table 1) (Sundström & Hutzinger, 1976; De Kok et al., 1979;
    US EPA, 1984; De Boer, 1989).

     n-Octanol/water partition
    coefficient (log Pow):        5.87-6.16

        From: Pijnenburg & Everts (1991).

    2.3  Analytical methods

        A multiresidue method has been developed for the analysis of PBDE
    residues in environmental samples (see General Introduction, section
    2.1 and Table 2).

    3.  SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE

    3.1  Natural occurrence

        Tetrabromodiphenyl ether has not been reported to occur naturally
    (see General Introduction, section 1.1).

    3.2  Anthropogenic sources

    3.2.1  Production levels and processes

        See sections 2 and 3 of Pentabromodiphenyl ether.

    3.2.2  Uses

        A thousand tonnes of tetrabromodiphenyl ether (TeBDE) were used in
    Japan in 1987 (Watanabe, 1987c).

    4.  ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION

    4.1  Pyrolysis

        The pyrolysis of Bromkal 70-DE (a mixture of tetrabromodiphenyl
    ether and pentabromodiphenyl ether) resulted in the formation of high
    levels of PBDF and PBDD: approximately 60%. The substance was
    pyrolysed at 800 °C in a quartz tube for 10 min (Thoma et al., 1986).
    Bromkal 70-DE produced complex mixtures of mono- to
    pentabromodibenzofurans and of mono- to tetrabromodibenzodioxins.
    Higher PBDF and PBDD were not found (Zacharewski et al., 1988).

    4.2  Ultimate fate following use

        For the ultimate fate of TeBDE following use in the environment
    see section 6.1. of the General Introduction.

    5.  ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE

    5.1  Environmental levels

    5.1.1  Soil and sediment

        Watanabe et al. (1987b) determined the residues of TeBDE in 9
    marine and/or estuarine sediment samples and 6 fresh water river
    sediment samples collected at different sites in Osaka during 1981-83.
    The nine marine and/or estuarine samples did not contain TeBDE (limit
    of determination < 2 µg/kg). Five out of 6 river sediment samples
    contained 12-31 µg TeBDE/kg.

        Sediment samples taken upstream and downstream from a factory were
    analysed for the presence of tetrabromobisphenol A (TBBP-A) and its
    dimethylated derivative. Besides TBBP-A, 2,2',4,4'-tetrabromodiphenyl
    ether was also found. The levels found upstream and downstream were
    3.5 and 840 µg/kg (IG), respectively (Sellström et al., 1990a,b).

        A laminated sediment core collected in the southern part of the
    Baltic Proper (Bornholm deep) was analysed for 2,2',4,4'-TeBDE. The
    core was cut into 5 mm slices down to 50 mm depth and in 10 mm slices
    from 50 to 90 mm depth. The concentration of TeBDE at 5 mm depth was
    1.6 µg/kg IG and decreased gradually to 0.13 µg/kg at 40 mm depth. At
    a depth of 90 mm, the concentration was 0.06 µg/kg (Nylund et al.,
    1992).

        Sellström et al. (1990b) analysed sewage sludge and found 15 µg
    2,2',4,4'-tetrabromodiphenyl ether/kg IG.

        Two sewage samples were collected from a Swedish treatment plant
    (Gothenburg) in September 1988 and analysed for PBDE. One homogenate
    was composed of samples (40 g/day) taken during a 32-day period with
    little rain. Another homogenate was composed of samples (100 g/day)
    taken during a rainy period of 7 days. TeBDE and PeBDE were found. The
    concentration of 2,2',4,4'-TeBDE was 15 µg/kg IG (Nylund et al.,
    1992).

    5.1.2  Fish and shellfish

        Watanabe et al. (1987b) determined the levels of TeBDE in fish and
    mussels collected from different places in Japan in 1981-85. In total,
    42 samples of mussel, mullet, goby, sardine, Japanese sea bass, horse
    mackerel, and hairtail, were analysed. Seven out of 17 fish and
    shellfish samples collected in the Osaka area contained 0.1-14.6 µg
    TeBDE/kg and 3 samples of mussels from Osaka bay contained
    1.6-14.6 µg/kg (wet weight). Single samples of sardine, Japanese sea
    bass, mackerel and hairtail contained levels ranging from 0.1 to
    0.8 µg TeBDE/kg. The other species did not contain TeBDE (limit of
    determination <0.1 µg/kg).

        De Boer (1989, 1990) measured the concentration of 2,2',4,4'-
    tetrabromodiphenyl ether in the liver of cod  (Gadus morhua),
    collected in the southern, central, and northern North Sea, in the
    period 1983-89. Each sample consisted of 25 fishes. The highest levels
    (up to 360 µg/kg) were found in the liver of cod from the southern
    part and the lowest levels (up to 68 µg/kg on a fat basis) in the
    northern part of the North Sea. The concentrations showed a decreasing
    trend from the southern region to the northern region. Herring
     (Clupea harengus) collected in the 3 areas and the Straits of Dover
    in 1985, contained average concentrations of 8.4-100 µg
    2,2',4,4'-TeBDE/kg on a fat basis. Eels  (Anguilla anguilla)
    collected in Dutch freshwater (rivers and lakes) at 10 places were
    analysed for the presence of 2,2',4,4'-TeBDE, during the period
    1983-89. The concentrations ranged from <20 to 1700 µg/kg, on a fat
    basis. In these marine and freshwater fish, 2,2',4,4'-TeBDE was always
    found as the main component, i.e., 70% of the total brominated
    diphenyl ethers.

        Fish were collected from 5 different localities along the Viskan
    and Haggan river system and the Klosterfjorden bay in Sweden. Muscle
    and, in some cases, also the liver of bream  (Abramis brama), eel
     (Anguilla anguilla), pike  (Esox lucius), sea trout  (Salmo ocla),
    and tench  (Tinca tinca) were analysed. Expressed on a fat weight
    basis, the highest level found was 110 mg PBDE/kg in the liver of a
    pike. This pike specimen contained 27 mg PBDE/kg fat in the muscle
    tissue. In addition to the 3 main components (1 tetrabromo- and 2
    pentabromo-isomers), another tetrabromo- as well as 1 tribromo- and 2
    hexabromo-isomers were identified by GC/MS. The maximum PBDE level

    obtained in the muscle of eel was 17 mg/kg fat. The analysis indicated
    that there was at least one local source of pollution along the River
    Haggan. 2,2',4,4'-TeBDE was the most abundant PBDE-component. In most
    samples, this compound accounted for 70-80% of total PBDE. The mean
    concentration of PBDE ranged from ND (0.1 mg/kg) to 88 mg/kg fat. Eel
    caught upstream, midstream, and in the Klosterfjorden bay contained
    mean concentrations of ND (0.1 mg/kg), 4.3-16, and 0.9-1.4 mg PBDE/kg
    fat, respectively (Andersson & Blomkvist, 1981).

        Muscle tissue from bream, pike, and perch from the Viskan and
    Haggan rivers in Sweden contained levels of 2,2',4,4'-TeBDE of between
    1 and 23 mg/kg (on a fat basis). Perch from the Viskan river had the
    highest levels (23 mg/kg) (Sellström et al., 1990b).

        A method for the multiresidue analysis of organic pollutants was
    applied to pooled muscle samples of 35 fresh water whitefish
     (Coregonus sp.), 15 samples of arctic char  (Salvelinus alpinus),
    and a total of 260 samples of herring  (Clupea harengus), collected
    at different places in Sweden during the period 1986-87. The average
    concentrations of 2,2',4,4'-tetrabromodiphenyl ether for whitefish,
    arctic char, and herring were 15, 400, and 59-450 µg/kg lipid,
    respectively (Jansson et al., 1993).

        Bream, pike, perch, and trout from Swedish waters contained
    250-750, 2000-6500, 2200-24 000, and 120-460 µg 2,2',4,4'-TeBDE/kg
    lipid, respectively. These samples were from background and
    industrialized areas (Sellström et al., 1993a). Pike samples from a
    Swedish lake indicated a 4-fold increase in the same isomer from 1974
    to 1991 (Sellström et al., 1993b).

    5.1.3  Birds

        Jansson et al. (1987) analysed pectoral muscle tissue of adult
    guillemot  (Uria aalge) nestling and wintering in the Baltic Sea,
    adult birds of the same species nestling and wintering in the North
    Sea, and adult guillemot collected at Spitzbergen. The pectoral muscle
    of a single, adult, white tailed sea eagle  (Haliaetus albicilla)
    from the Baltic Sea was also analysed. The concentrations of
    polybrominated diphenyl ethers (PBDE), calculated as Bromkal 70-5D, in
    the muscle of the guillemots of the Baltic, North Sea, and Spitzbergen
    were 370, 80 and 130 µg/kg, respectively, and that for the Baltic
    eagle, 350 µg/kg on a fat basis. The chromatographic pattern of the
    PBDE was similar to that of the Bromkal 70-5 product used as a
    reference substance.

        A method for multiresidue analysis was applied to pooled muscle
    samples of 35 osprey  (Pandion haliaetus), collected in Sweden in the
    period 1982-86. The average concentration of 2,2'4,4'-tetra-
    bromodiphenyl ether in osprey was 1800 µg/kg lipid (Jansson et al.,
    1993).

        A 10-fold increase in 2,2',4,4'-TeBDE has been indicated in
    guillemot eggs from the Baltic Sea (Sellström et al., 1993a) (Table
    29).

    5.1.4  Aquatic mammals

        Blubber samples of harbour seals (Phoca vitulina), collected in
    the southern Baltic Sea and the Kattegat, and a ringed seal  (Pusa
     hispida), collected at Spitzbergen, were analysed by Jansson et al.
    (1987). The concentrations of PBDE were 90, 10, and 40 µg/kg, on a fat
    basis, respectively. The chromatographic pattern of the PBDE was
    similar to that of the Bromkal 70-5 product used as a reference
    substance. Sellström et al. (1990b) reported a concentration of 730 µg
    PBDE/kg, on a fat basis, in a grey seal from the Baltic Sea.

        Seven pooled samples of blubber of ringed seal  (Pusa hispida),
    collected in 1981, and 8 pooled samples of blubber of grey seals
     (Halichoerus grypus), collected in Sweden in 1979-85, were analysed
    using a multiresidue analytical method. The average concentrations of
    2,2'4,4'-tetrabromodiphenyl ether were 47 and 650 µg/kg lipid,
    respectively (Jansson et al., 1993).

    Table 29.  Average concentrations of 2,2',4,4'-TeBDE in guillemot eggs
               from the Baltic Sea (in µg/kg lipid)a
                                                                         

    Sampling year                    2,2',4,4'-TeBDE
                                                                         

    1970                                   130
    1974                                   170
    1975                                   130
    1976                                   600
    1979                                   640
    1982                                   820
    1983                                   880
    1986                                  1200
    1987                                   650
    1989                                  1500
                                                                         

    aFrom:  Sellstrom et el. (1993a).

    5.1.5  Terrestrial mammals

        Multiresidue analysis of organic pollutants was applied to pooled
    muscle samples of 15 rabbits  (Oryctolagus cuniculus), 13 samples of
    moose  (Alces alces), and 31 samples of suet of reindeer  (Rangifer
     tarandus). The samples were collected in Sweden in the period
    1985-86. The average concentrations of 2,2',4,4'-tetrabromodiphenyl
    ether were <2, 0.82, 0.17 µg/kg lipid, for rabbit, moose, and
    reindeer, respectively Jansson et al., 1993).

    5.2  General population exposure

        No measurements are available of human exposure to TeBDE. In
    Sweden, the major human exposure is via fish-related food, and the
    levels of TeBDE in fish may be used to estimate this route of
    exposure. Normal fish intake in Sweden is about 30 g/day, and, if
    herring is used as a model fish, this will give an estimated intake of
    approximately 0.3 µg TeBDE/person per day (Personal Communication,
    Jansson).

        No data are available on occupational exposure during manufacture,
    formulation, or use.

    6.  KINETICS AND METABOLISM IN LABORATORY ANIMALS AND HUMANS

        The half-life of pentabromodiphenyl ether (Bromkal 70) was
    investigated in the perirenal fat of groups of 3 male and 3 female
    Wistar rats (weight 160-180g) following a single dose of 300 mg/kg
    body weight in peanut oil. Animals from the groups were killed on days
    1, 2, 3, 4, and 7, and then once a week for 10 weeks. Perirenal fat
    was collected and analysed. The half-life of TeBDE was 19.1 days for
    male rats and 29.9 days for female rats (Meyerinck et al., 1990).

    TRIBROMODIPHENYL ETHER

    1.  SUMMARY, EVALUATION, CONCLUSIONS AND RECOMMENDATIONS

        Tribromodiphenyl ether is not manufactured or used.

        No data are available on the following topics:

    *   Environmental transport, distribution, and transformation

    *   Kinetics and metabolism in laboratory animals and humans

    *   Effects on laboratory mammals and  in vitro test systems

    *   Effects on humans

    *   Effects on other organisms in the laboratory and field

    *   Previous evaluations by international bodies.

    1.1  Summary and evaluation

        There is no database on which to make an evaluation.

    1.2  Recommendations

        Levels of contamination of commercial products with
    tribromodiphenyl ether should be minimized to avoid contamination of
    the environment and the exposure of humans.

        Use of such commercial products leading to environmental
    contamination should be avoided.


    2.  IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, ANALYTICAL METHODS

    2.1  Identity

    Chemical structure:

    CHEMICAL STRUCTURE 9

    Chemical formula:             C12 H7 Br3 O

    Relative molecular mass       407.1

    Common names                  tribromodiphenyl ether (TrBDE);
                                  tribromodiphenyl oxide

    CAS registry number           49690-94-0

    CAS name                      1,1'-oxybis-tribromo-benzene

        On the basis of the chemical structure, there are 24 possible
    isomers of tribromodiphenyl ether.

    2.2  Physical and chemical properties

    Vapour pressure               4.70-4.95 Pa at 25 °C

     n-Octanol/water partition
    coefficient (log Pow)         5.47-5.58

        From: US EPA (1984, 1986); Watanabe (1987c); Pijnenburg & Everts
    (1991).

    2.3  Analytical methods

        No specific data are available (see General Introduction, section
    2.1 and Table 2).

    3.  SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE

        Tribromodiphenyl  ether has not been reported to occur naturally
    (see General Introduction, section 1.1).

    4.  ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE

    4.1  Environmental levels

    4.1.1  Birds

        Stafford (1983) found tribromodiphenyl ether (TrBDE) in the eggs
    of the fish-eating bird, the black skimmer  (Rynchos niger),
    collected from various nesting sites in Texas and Louisiana in the
    period 1980-81. The residues were not quantified.

    DIBROMODIPHENYL ETHER

    1.  SUMMARY, EVALUATION, CONCLUSIONS, AND RECOMMENDATIONS

        Dibromodiphenyl ether is not manufactured or used.

        No data are available on the following topics:

    *   Kinetics and metabolism in laboratory animals and humans

    *   Effects on humans

    *   Effects on other organisms in the laboratory and field

    *   Previous evaluations by international bodies.

    1.1  Summary and evaluation

        There is no database on which to make an evaluation.

    1.2  Recommendations

        Contamination of commercial products with dibromodiphenyl ether
    should be minimized to avoid contamination of the environment and
    exposure of humans.

        Use of such commercial products leading to environmental
    contamination should be avoided.

    2.  IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, ANALYTICAL METHODS

    2.1  Identity

    Chemical structure:

    CHEMICAL STRUCTURE 10

    Chemical formula:             C12 H8 Br2 O

    Relative molecular mass:      328.02

    Common name:                  dibromodiphenyl ether (DiBDE)
                                  dibromodiphenyl oxide

    CAS registry number:          2050-47-7

    Synonyms:                     bis(bromophenyl) ether,
                                  1.1'-oxybis (bromo), benzene

         On the basis of the chemical structure, there are 12 possible
    isomers of dibromodiphenyl ether, and  p,p'-dibromodiphenyl ether is
    one of them.

    2.2  Physical and chemical properties

          p,p'-Dibromodiphenyl ether (DiBDE) is a crystalline compound.

    Melting point:                60.5 °C (58-60 °C)

    Boiling point:                338-340 °C

    Vapour pressure:              3.85-4.02 Pa at 25 °C

    Specific gravity:             1.8 (solution)

    Solubility:                   very soluble in benzene, soluble in
                                  alcohol, and ethyl ether

     n-Octanol/water partition
    coefficient (log Pow):        5.03

    From:  US EPA (1984, 1986); Environment Agency Japan (1987); Pijnenburg
           & Everts (1991).

    2.3  Analytical methods

        No specific data are available (see General Introduction, section
    2.1, and Table 2).

    3.  SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE

    3.1  Natural occurrence

        Dibromodiphenyl ether has not been reported to occur naturally
    (see General Introduction, section 1.1).

    3.2  Anthropogenic sources

    3.2.1  Production levels end processes

         p,p'-Dibromodiphenyl ether is prepared from  p-phenoxyaniline
    by sequential treatment with HBr + NaNO2 and Br2 + HBr followed by
    warming in acetic acid (US EPA, 1986).

    4.  ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION

        The  in vitro microbial degradation of dibromodiphenyl ether was
    studied with a soil isolate, strain S93B1, identified as  Pseudomonas
     cruciviae. After enrichment and isolation, the bacteria was
    cultivated in an agar-slant at 30 °C for 12-17 days and growth was
    determined. Strain S93B1 did not grow on DiBDE as the sole source of
    carbon (Takase et al., 1986).

    5.  ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE

    5.1  Environmental levels

    5.1.1  Water

        In Japan,  p,p'-dibromodiphenyl ether was not detected in 27
    water samples (limit of determination 0.01-0.03 µg/litre) in an
    environmental survey in 1984 (Environment Agency Japan, 1987).

    5.1.2  Soil/sediment

        In Japan,  p,p'-dibromodiphenyl ether was not detected in 27
    sediment samples (limit of determination 0.05-13 µg/kg dry weight) in
    an environmental survey in 1984 (Environment Agency Japan, 1987).

    5.1.3  Birds

        Stafford (1983) found  p,p'-dibromodiphenyl ether in eggs of the
    fish-eating bird, the black-skimmer  (Rynchops niger), collected from
    various nesting sites in Texas and Louisiana in the period 1980-81.
    The residues were not quantified.

    5.2  General population exposure

        No data are available.

    6.  EFFECTS ON LABORATORY MAMMALS AND  IN VITRO TEST SYSTEMS

        No data are available on the following topics:

    *   Short-and long-term toxicity

    *   Skin and eye irritation, sensitization

    *   Reproductive toxicity, embryotoxicity, teratogenicity,
        mutagenicity, and carcinogenicity.

    6.1  Single exposure

        The acute intraperitoneal LD50 in mice is 125 mg/kg body weight
    (US EPA, 1984).

    6.2  Other special studies

    6.2.1  Liver

        Carlson (1980a) and Kociba (undated) tested  p,p'-dibromo-
    diphenyl ether in a dose of 0.1 mmol/kg body weight per day, by
    gavage, in corn oil, in male Sprague Dawley rats (200-250 g)
    for 14 days. Twenty-four hours after the last (seventh) dose,
    increases in liver/body weight ratio, NADPH cytochrome c-reductase,
    and cytochrome P-450 were found.

    MONOBROMODIPHENYL ETHER

    1.  SUMMARY, EVALUATION, CONCLUSIONS AND RECOMMENDATIONS

        No data are available on the following topics:

    *   Kinetics and metabolism in laboratory animals and humans

    *   Effects on humans

    *   Previous evaluations by international bodies.

    1.1  Summary and evaluation

    1.1.1  Physical and chemical properties

        There are 3 possible isomers of monobromodiphenyl ether.

         p-Bromodiphenyl ether is a liquid at ambient temperature with a
    boiling point of 305-310 °C. Its solubility in water is calculated to
    be 48 mg/litre. The log  n-octanol water partition coefficient is
    between 4 and 5. Vapour pressure at 20 °C is 0.0015 mmHg.

    1.1.2  Production and uses

        MBDE is not used as a flame retardant. A report of production
    appeared in 1977, but the use is unknown.

    1.1.3  Environmental transport, distribution, and transformation

        The half-life of volatilization from water is in the range of
    hundreds of days.

        MBDE did not significantly biodegrade in a 7-day culture with
    microorganisms from domestic waste water, but it has been reported to
    degrade by 95% in activated sewage sludge. A single study showed a
    strain of soil bacteria incapable of degrading MBDE as a sole carbon
    source.

    1.1.4  Environmental levels and human exposure

        MBDE has been detected in surface water samples taken near
    industrial sites in the USA but was not found in a similar survey in
    Japan. It was also detected in soil water close to an industrial plant
    in the USA. MBDE has been detected in aquatic sediment and aquatic
    biota in the USA.

    1.1.5  Kinetics and metabolism in laboratory animals and humans

        No data are available.

    1.1.6  Effects on laboratory mammals and  in vitro test systems

        MBDE is not teratogenic, but there are no data on the acute,
    short-term, or long-term toxicity of MBDE and therefore no evaluation
    can be made.

    1.1.7  Effects on humans

        No data are available.

    1.1.8  Effects on other organisms in the laboratory and field

        A 96-h LC50 for bluegill sunfish has been reported at
    4.9 mg/litre with a no-observed-effect concentration at less than
    2.8 mg/litre. The 48-h LC50 for waterflea was 0.36 mg/litre with a
    NOEC at less than 0.046 mg/litre.

    1.2  Conclusions and recommendations

        Monobromodiphenyl ether does not have any flame retardant
    properties. It can accumulate in organisms in the environment and has
    been detected in different environmental compartments. There is some
    evidence that it can be biodegraded.

        The limited information means that conclusions concerning exposure
    levels and effects on the general population and organisms in the
    environment cannot be reached.

        There is no toxicological data base to support its use.

        Uses leading to environmental contamination should be avoided.

    2.  IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, ANALYTICAL METHODS

    2.1  Identity

    Chemical structure:

    CHEMICAL STRUCTURE 11

    Chemical formula:             C12H9BrO

    Relative molecular mass:      249.11

    Common names:                 monobromodiphenyl ether (MBDE)
                                  mono bromodiphenyl oxide

    CAS registry number:          101-55-3

    CAS name:                     bromo-4-phenoxybenzene

    Synonyms:                     bromophenylphenyl ether, bromodiphenyl
                                  ether, bromophenyl ether,
                                  bromophenoxybenzene

    Trade names:                  HSDB 2747; NSC

    On the basis of the chemical structure, there are 3 possible isomers
    of monobromodiphenyl ether.  p-Monobromodiphenyl ether is one of
    them.

    2.2  Physical and chemical properties

         p-Bromodiphenyl ether is a liquid at common ambient
    temperatures.

    Melting point:                18.72 °C

    Boiling point:                310.14 °C (305 °C

    Vapour pressure at 20 °C:     0.0015 mmHg

    Specific gravity:             1.449 (1.4208 at 20 °C)

    Refractive index, n 20/D:     1.607

    Flash point:                  >230°F

    Solubility at 25 °C:          4.8 mg/litre water (calculated),
                                  soluble in ethyl ether

     n-Octanol/water partition
    coefficient (log Pow):        4.28 (4.08-4.94)

        From: US EPA (1984, 1986).


    2.3  Analytical methods

         p-Monobromodiphenyl ether (MBDE) can be determined by the
    standard US EPA method 611-Haloethers. Chromatographic conditions are
    described in US EPA (1986). The limit of determination in municipal
    and industrial waste waters is 2.3 µg/litre. Zogorski (1984) reported
    a limit of determination of 0.01 µg/litre using a gas chromatograph
    equipped with an electron capture detector. McMahon (1983) applied
    GC-MS (US EPA method 625) using a halide specific detector. Gurka et
    al. (1982) used GC/Fourier transform infrared spectroscopy to detect
     p-monobromodiphenyl ether (see also General Introduction, section
    2.1 and Table 2).

    3.  SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE

    3.1  Natural occurrence

        Monobromodiphenyl ether has not been reported to occur naturally
    (see General Introduction, section 1.1).

    3.2  Anthropogenic sources

    3.2.1  Production levels and processes

         p-Monobromodiphenyl ether is prepared by brominating diphenyl
    ether with Br2 at 95-100 °C in carbon tetrachloride (US EPA, 1986).

        The production range (includes importation volumes) statistics
    from the 1977 TSCA Inventory were up to 450 kg of  p-mono-
    bromodiphenyl ether (US EPA, 1986).

    3.2.2  Uses

        No data are available.

    4.  ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION

    4.1  Transport and distribution between media

        The half-life of  p-monobromodiphenyl ether with respect to
    volatilization has been estimated to be within the range of hundreds
    of days (MacKay & Leinonen, 1975).

        In contrast, by analogy to  p-monochlorodiphenyl, Callahan et al.
    (1979) estimated the half-life of  p-monobromodiphenyl ether to be
    10 h. However, sorption of the agent by organic material in water will
    prolong its evaporative half-life in natural bodies of water. This
    value should be considered a minimum.

    4.2  Biotransformation

    4.2.1  Biodegradation

         p-Monobromodiphenyl ether was not significantly biodegradable in
    a 7-day static-culture flask-screening procedure of Bunch and Chambers
    utilizing biochemical oxygen demand (BOD) dilution water containing
    5 mg of yeast extract/litre, as the synthetic medium; 5 and
    10 mg/litre concentrations of the test compound, a 7-day static
    incubation of 25 °C in the dark, followed by three weekly subcultures
    (totalling 28 days of incubation), and incorporating settled domestic
    waste water as microbial inoculum. At a test compound concentration of
    5 mg/litre, only 2 out of 4 cultures showed any biodegradation in 7
    days (19 and 36%), and, at a concentration of 10 mg/litre, only one
    out of 4 showed biodegradation (19%) (Tabak et al., 1981).

         p-Monobromodiphenyl ether was not able to support the growth of
    Alcaligenes BM2, a strain of soil bacteria capable of using PCB
    (dichloro-) mixtures as the sole source of carbon (Yagi & Sudo, 1980).
    However,  p-monobromodiphenyl ether was reported to be 95%
    biodegradable when introduced as a pollutant (360 µg/litre) in a
    full-scale activated sludge treatment system (US EPA, 1986).

        The  in vitro microbial degradation of  p-monobromodiphenyl
    ether was studied with a soil isolate, strain S93B1, identified as
     Pseudomonas crucivae. After enrichment and isolation, the bacteria
    were cultivated in an agar-slant at 30 °C for 12-17 days and growth
    was determined. Strain S93B1 did not grow on the biphenyl ether as the
    sole source of carbon (Takase et al., 1986).

    5.  ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE

        No data are available on general population exposure or on
    occupational exposure during manufacture, formulation, or use.

    5.1  Environmental levels

    5.1.1  Water

        According to US EPA (1986), there are monitoring data for
     p-monobromodiphenyl ether in water in the USA. The mean
    concentration was 0.2 mg/litre (range 0-202.7 mg/litre, 2193 listings)
    in water. Most of these listings concerned river water samples taken
    near industrial sites. Only a few groundwater and community
    drinking-water samples were included (no further details were
    available). Plumb (1991) reported the presence of  p-monobromo-
    diphenyl ether in groundwater from only 1 out of 479 disposal sites
    that were analysed in the USA.

        In Japan,  p-monobromodiphenyl ether was not detected in 27 water
    samples (limit of determination 0.15-0.5 µg/litre) in an environmental
    survey in 1984 (Environment Agency Japan, 1987).

    5.1.2  Soil/sediment

        According to US EPA (1986), there are numerous US monitoring data
    for  p-monobromodiphenyl ether in sediments. The mean concentration
    was 3.5 mg/kg (range 0-380 mg/kg, 585 listings) (no further details
    are available).

        In Japan,  p-monobromodiphenyl ether was not detected in 27
    sediment samples (limit of determination 2.5-120 µg/kg dry weight) in
    an environmental survey in 1984 (Environment Agency Japan, 1987).

    5.1.3  Aquatic organisms

        According to US EPA (1986) there are numerous US monitoring data
    for  p-monobromodiphenyl ether in tissue from aquatic organisms. The
    concentrations were 2.0 mg/kg (range 070.0 mg/kg, 346 listings) (no
    further details are available).

    6.  EFFECTS ON LABORATORY MAMMALS AND  IN VITRO TEST SYSTEMS

        No data are available on the following topics:

    *   Single exposure

    *   Short-term exposure

    *   Long-term exposure

    *   Skin and eye irritation; sensitization

    *   Mutagenicity and related endpoints.

    6.1  Reproductive toxicity, embryotoxicity, and teratogenicity

        Outbred Swiss (CD-1) mice (age 60 days) were treated with
     p-monobromodiphenyl ether (95%). There were 20 and 21 mice
    respectively in these treatment groups and 51 and 55 mice in untreated
    and vehicle control (1 ml corn oil/kg) groups, respectively. Two
    females per group were mated per male, until a copulation plug was
    found, or for maximum 5 days. MBDE in corn oil was administered by
    gavage in dose levels of 0, 100 or 1.000 mg/kg body weight/day, from
    day 5 up to day 14 of gestation. Pups were counted and weighed (by
    litter) on postnatal days 1, 3, 5, 10 and 15; they were sexed and
    weaned on day 21 and autopsied on days 25 and 30 to determine gross
    abnormalities and the weights of Harderian glands, liver, and kidneys.
    No adverse effects on any of these parameters were observed (Francis,
    1989).

    6.2  Carcinogenicity

        Theiss et al. (1977) tested  p-monobromodiphenyl ether (MBDE) in
    a short-term screening assay: the strain A mouse pulmonary tumour
    assay. Four groups of 20 A/St male mice (6-8 weeks old) were given 24
    intraperitoneal injections of tricaprylin (solvent-control), 23 i.p.
    injections of 40 mg (low-dose), 17 injections of 100 mg (mid-dose) and
    18 injections of 200 mg MBDE/kg body weight (high-dose), three times
    per week. Total doses administered in the four groups were 0, 920,
    1700, and 3600 mg/kg body weight, respectively. Twenty-four weeks
    after the first injection, the mice were sacrificed and the lungs
    examined. The number of lung tumours/mouse and survival rates of the
    treated animals were not significantly different from the control
    animals. The number of lung tumours/mouse were; control 0.39 ± 0.06;
    low-dose 0.18 ± 0.10, mid-dose 0.15 ± 0.10 and high-dose 0.31 ± 0.15.
    MBDE was negative in this pulmonary assay.

    7.  EFFECTS ON OTHER ORGANISMS IN THE LABORATORY AND FIELD

        The effects of acute exposure to  p-monobromodiphenyl ether have
    been studied in several species of aquatic invertebrates and fish. The
    results are summarized in Table 30. The water flea  (Daphnia magna),
    is more sensitive than fish to  p-monobromodiphenyl ether (US EPA,
    1984).

        In an early-life-stage (embryo-larval) test on fathead minnow,
    conducted with  p-monobromodiphenyl ether, adverse effects on
    survival and growth were produced. The geometric mean of the highest
    no-effect level was 0.122 mg/litre (US EPA, 1984).


        Table 30.  Acute toxic effects of  p-monobromodiphenyl ether on aquatic organismsa
                                                                                                                                

    Species                   Exposure                         Mean         Effect             Reference
                              duration   Method            concentration
                                 (h)                        (mg/litre)
                                                                                                                                

    Rainbow trout                24      static-aerated         5.0         stress observed    Applegate et al. (1957)
    (Oncorhynchus mykiss)b
    Bluegill sunfish             24      static-aerated         5.0         stress observed    Applegate et al. (1957)
    (Lepomis macrochirus)

    Bluegill sunfish             24      static                50.9c        LC50               US EPA (1978);
    (Lepomis macrochirus)
                                                                                               Buccafusco et al. (1981)
                                 48      static                9.62         LC50               US EPA (1978)
                                 72      static                4.94         LC50               US EPA (1978)
                                 96      static                4.94         LC50               US EPA (1978)
                                 96      static              < 2.80         no effect          US EPA (1978)
    See lamprey                  24      static-aerated         5.0         stress observed    Applegate et al. (1957)
    (Petromyzon marinus)

    Water flea                   24      static                0.46         LC50               US EPA (1978); LeBlanc (1980)
    (Daphnia magna)              48      static                0.36         LC50               US EPA (1978); LeBlanc (1980)
                                 48      static              < 0.046        no effect          US EPA (1978)
                                                                                                                                

    a  From: US EPA (1984).
    b  Old name = Salmo Gairdneri.
    c  This dose exceeds the solubility of the test compound in water at 25 °C (4.6 mg/litre).

    

    REFERENCES

    AIHA (1981) Decabromo-diphenyloxide. Workplace environmental exposure
    level guide. Am Ind Hyg Assoc J, 42: A76-A77.

    Andersson O & Blomkvist G (1981) Polybrominated aromatic pollutants
    found in fish in Sweden. Chemosphere, 10(9): 1051-1060.

    Anon (1989) Draft evaluation report on flame retardants; PBB's and
    PBBO's (in Dutch).

    Applegate VC, Howell JH, Hall AE, & Smith MA (1957) Toxicity of 4,346
    chemicals to larval lampreys and fish. Washington, DC, US Department
    of the Interior, Fish and Wildlife Service (Special Scientific Report,
    Fish No. 207).

    Arias (1992) Brominated diphenyloxides as flame retardants; Bromine
    based chemicals. Consultant report to the OECD, Paris.

    Bahn A, Bialik O, Oler J, Houten L, & Landau E (1980) Health
    assessment of occupational exposure to polybrominated biphenyl (PBB)
    and polybrominated biphenyloxide (PBBO). Washington, DC, US
    Environmental Protection Agency, Office of Pesticides and Toxic
    Substances, 72 pp (ISS EPA 560/6-80-001; NTIS No. PB81-159675).

    Ball M, Päpke O, & Lis A (1991) [Further investigation on the
    formation of polybrominated dioxins and furans during thermal stress
    of flameproof plastics and textiles. Sub-project 1.] Berlin, Federal
    Office for the Environment (Research report No. 10403364/01; UBA-FB
    91-082) (in German).

    Ball M, Päpke O, & Lis A (1992) [Further investigation on the
    formation of polybrominated dioxins and furans during thermal stress
    of flameproof plastics and textiles. Sub-projects 1 and 2.] Berlin,
    Federal Office for the Environment (Research report Nos. 10403364/01 &
    /02; UBA-FB 91-082 & 92-097) (in German).

    BFRIP (1990) Brominated flame retardants. A review of recent research
    (Compiled by The Brominated Flame Retardant Industry Panel and The
    European Brominated Flame Retardant Industry Panel). West Lafayette,
    Indiana, USA, BFRIP (Unpublished report No. III/4143/90, submitted to
    WHO by BFRIP).

    Bialik O (1982) Endocrine function of workers exposed to PBB and PBBO:
    Terminal progress report. Cincinnati, Ohio, National Institute for
    Occupational Safety and Health.

    Bieniek D, Bahadir M, & Korte F (1989) Formation of heterocyclic
    hazardous compounds by thermal degradation of organic compounds.
    Heterocycles, 28:719-722.

    Breslin WJ, Kirk HD, & Zimmer MA (1989) Teratogenic evaluation of a
    polybromodiphenyl oxide mixture in New Zealand White rabbits following
    oral exposure. Fundam Appl Toxicol, 12: 151-157.

    Bromine Compounds Ltd (1992) Material safety data sheet FR-1210. Beer
    Sheva, Israel, Bromine Compounds Ltd, pp 1-5.

    Brosier JS, Blanchard FA, & Takahashi IT (1972) Concentrations of
    octabromodiphenyl and decabromodiphenyloxide in aquaria water and
    trout flesh. Midland, Michigan, Dow Chemical Company (Unpublished
    report No. AL 37448, submitted to WHO by BFRIP).

    Bruckmann P, Hackhe K, Ball M, Lis A, & Papke O (1990) Degassing of
    PBDD/PBDFs from a television set - PBDD/PBDF levels after a fire in a
    stock house two case studies. In: Freij L ed. Proceedings of the
    Workshop on Brominated Aromatic Flame Retardants, Skokloster, Sweden,
    24-26 October 1989. Solna, National Chemicals Inspectorate (KEMI),
    pp 99-104.

    Buccafusco RJ, Ells SJ, & Leblanc GA (1981) Acute toxicity of priority
    pollutants to bluegill  (Lepomis macrochirus). Bull Environ Contam
    Toxicol, 26(4): 446-452.

    Buser HR (1986) Polybrominated dibenzofurans and dibenzo- p-dioxins:
    Thermal reaction products of polybrominated diphenylether flame
    retardants. Environ Sci Technol, 20(4): 404-408.

    Carlson GP (1980a) Induction of xenobiotic metabolism in rats by
    short-term administration of brominated diphenylethers. Toxicol Lett,
    5: 19-25.

    Carlson GP (1980b) Induction of xenobiotic metabolism in rats by
    brominated diphenylethers administered for 90 days. Toxicol Lett,
    6: 207-212.

    Carte B & Faulkner DJ (1981) Polybrominated diphenyl ethers from
     Dysidea herbacea. Dysidea chlorea and  Phyllospongia foliascens.
    Tetrahedron, 37: 2335-2339.

    CBC (1982) The bioaccumulation of compound S-511 by carp. Tokyo,
    Chemicals Inspection and Testing Institute, Chemical Biotesting Center
    (Unpublished report).

    CEM (1989) Polybrominated dibenzodioxins and dibenzofurans
    (PBDDs/PBDFs) from flame retardants containing bromine. Assessment of
    risk and proposed measures. Report by the Brominated flame retardants
    CEM Working Group to the Conference of Environment Ministers, Bonn,
    September 1989. (Report III/4299/89. Appendix).

    Chemag (1988) Information sheet on Chemflam 011. Frankfurt am Main,
    Chemag Aktiengesellschaft, p 1.

    Clausen E, Lahaniatis ES, Bahadir M, & Bieniek D (1987) [Determination
    of brominated dibenzofurans formed during the thermolysis of polymers
    with decabromodiphenylether as flame-proofing agent.] Fresenius Z Anal
    Chem, 327: 297300 (in German).

    Craig DK, Mitchum RK, Bauer MR, Yancey MF, Peters AC, & Ioiner RL
    (1989) Determination of polybrominated dibenzo- p-dioxins and
    polybrominated dibenzofurans in CYCOLAC plastic resins and the fumes
    evolved during normal thermal processing. Final report. Columbus.
    Ohio, Battelle (Report to General Electric Company, Mt. Vernon,
    Indiana, submitted to WHO by BFRIP).

    Cramer PH, Stanley JS, & Thornburg KR (1990a) Mass spectral
    confirmation of chlorinated and brominated diphenyl ether in human
    adipose tissues. Kansas City, Missouri, Midwest Research Institute
    (Prepared for the US Environmental Protection Agency, Washington) (US
    NTIS report PB91-159699).

    Cramer PH, Ayling RE, Thornburg KR, Stanley JS, Remmers JC, Breen JJ,
    & Schwemberger J (1990b) Evaluation of an analytical method for the
    determination of polybrominated dibenzo- p-dioxins/dibenzofurans
    (PBDD/PBDF) in human adipose. Chemosphere, 20(7-9): 821-827.

    Davidson JS & Ariano JM (1986) Decabromodiphenylether (DE-83):
    Determination of area percent assay. Analytical method No. QC-86-02.
    West Lafayette, Indiana, Great Lakes Chemical Corporation (Report
    submitted to WHO by BFRIP).

    De Boer J (1989) Organochlorine compounds and bromediphenylethers in
    livers of Atlantic  cod (Gadus morhua) from the North Sea, 1977-1987.
    Chemosphere, 18(11/12): 2131-2140.

    De Boer J (1990) Brominated diphenylethers in Dutch freshwater and
    marine fish. In: Hutzinger O & Fiedler H ed. Dioxin'90. EPRI-Seminar.
    Tenth International Symposium on Chlorinated Dioxins and Related
    Compounds. Volume 2: Organohalogenated compounds (Short papers).
    Bayreuth, Germany, Ecoinforma Press, pp 315-318.

    DeCarlo VJ (1979) Studies on brominated chemicals in the environment.
    Ann NY Acad Sci, 320: 678-681.

    Dieter MP (1979) Special studies protocol. Washington, Memorandum of
    the Department of Health, Education and Welfare. Public Health
    Service, National Institute of Health, National Cancer Institute.

    Dow Chemical Company (1978) Compound: Decabromodiphenyl oxide
    (Analytical method). Midland, Michigan, Dow Chemical Company,
    pp 609-620 (Report prepared by Tracor Jitco, Inc., Rockville,
    Maryland) (Report No. 3250, submitted to WHO by BFRIP).

    Dumler R, Lenoir D, & Hutzinger O (1990) Formation of brominated
    dibenzofurans and -dioxins from the combustion of the flame retardant
    decabromodiphenyl ether under different conditions. In: Hutzinger O &
    Fiedler H ed. Dioxin'90. EPRI-Seminar. Tenth International Symposium
    on Chlorinated Dioxins and Related Compounds. Volume 2:
    Organohalogenated compounds (short papers). Bayreuth, Germany,
    Ecoinforma Press, pp 325-328.

    Dumler R, Thoma H, Lenoir D, & Hutzinger O (1989a) Thermal formation
    of polybrominated dibenzodioxins (PBDD) and dibenzofurans (PBDF) from
    bromine containing flame retardants. Chemosphere, 19(1-6): 305-308.

    Dumler R, Lenoir D, Thoma H, & Hutzinger O (1989b) Thermal formation
    of polybrominated dibenzofurans from decabromodiphenyl ether in a
    polybutylene-terephthalate polymer matrix. J Anal Appl Pyrolysis,
    16: 153-158.

    EBFRIP (1990) Information on polybrominated diphenylethers (PBDE's).
    Economic, technical and regulatory assessment of the European
    Brominated Flame Retardant Industry Panel - Responses to questions
    submitted by EEC, Brussels. Rijswijk (NL), The European Brominated
    Flame Retardant Industry Panel.

    El Dareer SM, Kalin JR, Tillcry KF, & Hill DL (1987) Disposition of
    decabromodiphenyl ether in rats dosed intravenously or by feeding.
    J Toxicol Environ Health, 22: 405-415.

    Environment Agency Japan (1983) Environmental monitoring of chemicals.
    Environmental survey report of F.Y. 1980 and 1981. Tokyo, Environment
    Agency Japan, Department of Environmental Health, Office of Health
    Studies.

    Environment Agency Japan (1987) Chemicals in the environment. Report
    on environmental survey and wildlife monitoring of chemicals in F.Y.
    1984 and 1985. Tokyo, Environment Agency Japan, Department of
    Environmental Health, Office of Health Studies.

    Environment Agency Japan (1989) Chemicals in the environment. Report
    on environmental survey and wildlife monitoring of chemicals in F.Y.
    1986 and 1987. Tokyo, Environment Agency Japan, Department of
    Environmental Health, Office of Health Studies.

    Environment Agency Japan (1991) Chemicals in the environment. Report
    on environmental survey and wildlife monitoring of chemicals in F.Y.
    1988 and 1989. Tokyo, Environment Agency Japan, Department of
    Environmental Health, Office of Health Studies.

    Ethyl Corporation (1986) Laboratory report: Primary eye irritation.
    Saytex 102. Baton Rouge, Louisiana, Ethyl Corporation (Report
    No. PH 421-ET-010-86) (Report submitted to WHO by BFRIP).

    Ethyl Corporation (1992a) Information sheet from Ethyl Corporation on
    Saytex 102E. Baton Rouge, Louisiana, Ethyl Corporation (Report
    submitted to WHO by BFRIP).

    Ethyl Corporation (1992b) Information sheet from Ethyl Corporation on
    Saytex 111. Baton Rouge, Louisiana, Ethyl Corporation (Report
    submitted to WHO by BFRIP).

    Faulkner DJ (1988) Brominated marine natural products. In: Price D,
    Iddon B, & Wakefield BJ ed. Bromine Compound: Chem. Appl.,
    (Proceedings, International Conference on Chemical Applications of
    Bromine and its Compounds.) Amsterdam, Oxford, New York, Elsevier
    Science Publishers, Chapter 2, pp 121-144.

    Faulkner DJ (1990) Naturally-occurring brominated compounds. In: Freij
    L ed. Proceedings of the Workshop on Brominated Aromatic Flame
    Retardants, Skoldoster, Sweden, 24-26 October 1989. Solna, National
    Chemicals Inspectorate, pp 121-144.

    Fernandez P, Grifoll M, Solahas AM, Bayona JM, & Albaiges J (1992)
    Bioasssay-directed chemical analysis of genotoxic components in
    coastal sediments. Environ Sci Technol, 26: 817-829.

    Flick EW (1986) Plastics additives: An industrial guide. Section IX -
    Fire and flame retardants. Park Ridge, New Jersey, Noyes Publications,
    pp 213-248.

    Francis BM (1989) Relative developmental toxicities of nine diphenyl
    ethers related to nitrofen. Environ Toxicol Chem, 8: 681-688.

    Fresenius Institute (1990) Summary results on pyrolysis of different
    types of ABS. Battelle report on contents and vapour-emission of PBDD
    resp. PBDF's. Memorandum from Leeuwenburgh W.F., General Electric
    Plastics ABS, BV. Amsterdam. 12 March 1990 (Report submitted to WHO by
    BFRIP).

    Fulfs JC (1987a) Rabbit ear bioassay for comedogenicity, dose-range
    finding study for soot and char generated from the combustion of high
    impact polystyrene. Fort Collins, CO, USA, Inhausen Research
    Institute, Inc. (Report to Ethyl Corporation, Baton Rouge, Florida,
    submitted to WHO by BFRIP).

    Fulfs JC (1987b) Rabbit ear bioassay for comedogenicity, dose-range
    finding study for soot and char generated from the combustion of high
    impact polystyrene flame retarded with decabromodiphenyloxide and
    antimony oxide. Fort Collins, CO, USA, Inhausen Research Institute,
    Inc. (Report to Ethyl Corporation, Baton Rouge, Florida, submitted to
    WHO by BFRIP).

    Fulfs JC & Dahlgren RR (1987a) Acute oral toxicity in the rat of soot
    and char generated from the combustion of high impact polystyrene
    (HIPS). Fort Collins, CO, USA, Inhausen Research Institute, Inc.
    (Report to Ethyl Corporation, Baton Rouge, Florida, submitted to WHO
    by BFRIP).

    Fulfs JC & Dahlgren RR (1987b) Acute oral toxicity in the rat of soot
    and char generated from the combustion of high impact polystyrene
    flame retarded with decabromodiphenyloxide and antimony trioxide (HIPS
    FR). Fort Collins, CO, USA, Inhausen Research Institute, Inc. (Report
    to Ethyl Corporation, Baton Rouge, Florida, submitted to WHO by
    BFRIP).

    Fulfs JC & Dahlgren RR (1987c) Rabbit ear biGassay for comedogemcity:
    Multiple-dose-level definitive study for soot and char generated from
    the combustion of high impact polystyrene. Fort Collins, CO, USA,
    Inhausen Research Institute, Inc. (Report to Ethyl Corporation, Baton
    Rouge, Florida, submitted to WHO by BFRIP).

    Fulfs JC & Dahlgren RR (1987d) Rabbit ear bioassay for comedogenicity,
    multiple-dose-level definitive study for soot and char generated from
    the combustion of high impact polystyrene flame retarded with
    decabromo-diphenyloxide and antimony trioxide. Fort Collins, CO, USA,
    Inhausen Research Institute, Inc. (Report to Ethyl Corporation, Baton
    Rouge, Florida, submitted to WHO by BFRIP).

    Great Lakes Chemical Corporation (1987) Toxicity data of
    octabromo-diphenyloxide (DE-79). West Lafayette, Indiana, Great Lakes
    Chemical Corporation (Unpublished data submitted to WHO by BFRIP).

    Great Lakes Chemical Corporation (1990a) Great Lakes DE-79tm: Product
    information. West Lafayette, Indiana, Great Lakes Chemical Corporation
    (Report submitted to WHO by BFRIP).

    Great Lakes Chemical Corporation (1990b) Great Lakes DE-83Rtm: Product
    information. West Lafayette, Indiana, Great Lakes Chemical Corporation
    (Report submitted to WHO by BFRIP).

    Great Lakes Chemical Corporation (Undated a) Toxicity data of
    pentabromo-diphenyloxide. West Lafayette, Indiana, Great Lakes
    Chemical Corporation (Unpublished report submitted to WHO by BFRIP).

    Great Lakes Chemical Corporation (Undated b) Toxicity data of
    decabromo-diphenyloxide. West Lafayette, Indiana, Great Lakes Chemical
    Corporation (Unpublished report submitted to WHO by BFRIP).

    Gurka DF, Laska PR, & Titus R (1982) The capability of GC/FT-IR to
    identify toxic substances in environmental sample extracts.
    J Chromatogr Sci, 20: 145-154.

    Hagenmaier H, She J, Dawidowsky N, Thomas B, & Dusterholt L (1991)
    Analysis of sewage sludges for polyhalogenated dibenzo- p-dioxins,
    dibenzofurans and diphenylethers. In: Dioxin'91. Abstract from the
    11th International Symposium on Chlorinated Dioxins and Related
    Compounds, Research Triangle Park, North Carolina, 23-27 September
    1991, p 112.

    Hallenbeck D (1993) Freezing point of DE-71. Inter-Office memorandum,
    Great Lakes Chemical Corporation. June 29, 1993 (Report submitted to
    WHO by BFRIP).

    Hamm S & Theisen J (1992) Formation of polybrominated dibenzofurans
    and polybrominated dibenzo(p)dioxins at fires of electrical
    appliances. Poster presented at Dioxin'92. 12th International
    Symposium on Dioxins and Related Compounds, Tampere, Finland, 24-28
    August 1992. Munster, Society for Workplace and Environmental Analysis
    GmbH.

    Hanberg A, Stahlberg M, Georgellis A, De Wit C, & Ahlborg UG (1991)
    Swedish dioxin survey: Evaluation of the H-4-II E bioassy for
    screening environmental samples for dioxin:like enzyme induction.
    Pharmacol Toxicol, 69: 442-449.

    Hanley TR Jr (1985) Decabromodiphenyloxide: A summary of an oral
    teratology study in Sprague-Dawley rats. Midland, Michigan, Dow
    Chemical Company (Unpublished report submitted to WHO by BFRIP).

    Hefner RE Jr (1973) A study of the rate of hemolysis induced by
    decabromo-diphenoxide (DBDPO) particles with washed rat erythrocytes
     in vitro. Midland, Michigan, Dow Chemical Company (Unpublished
    report submitted to WHO by BFRIP).

    Hoechst Celanese Corporation (1988) Report of air sampling for the
    presence of polybrominated dibenzodioxins and dibenzofurans during the
    production of polybutylene terephthalate resin with decabromodiphenyl
    oxide (Unpublished report submitted to WHO by BFRIP).

    Huff JE, Eustis SL, & Haseman JK (1989) Occurrence and relevance of
    chemically induced benign neoplasms in long-term carcinogenicity
    studies. Cancer Metastasis, 8: 121.

    Hutzinger O & Thoma H (1987) Polybrominated dibenzo- p-dioxins and
    dibenzofurans: The flame retardant issue. Chemosphere,
    16(8/9): 1877-1880.

    Hutzinger O, Sundstrom G, & Safe S (1976) Environmental chemistry of
    flame retardants. Part. I. Introduction and principles. Chemosphere,
    1: 3-10.

    IARC (1990) Some flame retardants and textile chemicals, and exposures
    in the textile manufacturing industry. Lyon, International Agency for
    Research on Cancer, 345 pp (IARC Monographs on the Evaluation of
    Carcinogenic Risks to Humans, Volume 48).

    Industrial Bio-Test Laboratories (1975) Human repeated insult patch
    test with DBDO-1 and XD 8186.02. Northbrook, Illinois, USA. (Report to
    Dow Chemical Company, Midland, Michigan) (Report No. IBT 636-0654,
    submitted to WHO by BFRIP).

    IRPTC (1988) Data profiles on flame retardants; Deca-, octa- and
    pentabromodiphenyloxide. Geneva, International Register of Potentially
    Toxic Chemicals, United Nations Environment Programme.

    Jansson B, Asplund L, & olsson M (1987) Brominated flame retardants --
    Ubiquitous environmental pollutants? Chemosphere,
    16(10-12): 2343-2349.

    Jansson B, Andersson R, Asplund L, Bergman A, Litzen K, Nylund K,
    Reutergardh L, Sellström U, Uvemo U-B, Wahlberg C, & Wideqvist U
    (1991) Multiresidue method for the gas-chromatographic analysis of
    some polychlorinated and polybrominated pollutants in biological
    samples. Fresenius J Anal Chem, 340: 439-445.

    Jansson B, Andersson R, Asplund L, Litzen K, Nylund K, Sellström U,
    Uvemo U-B, Wahlberg C, Wideqvist U, Odsjo T, & Olsson M (1993)
    Chlorinated and brominated persistent organic compounds in biological
    samples from the environment. Accepted for publication in Environ.
    Toxicol. Chem., 12(7): 1163-1174.

    Jersey G-C, Frauson LE, & Schuetz DJ (1976) Pulmonary clearance and
    tissue response following a single intratracheal injection of
    decabromo-diphenyloxide (DBDPO) dust in male rats. Midland, Michigan,
    Dow Chemical Company (Unpublished report No. HET K-47298-(21),
    submitted to WHO by BFRIP).

    Kaart KS & Kokk KY (1987) Spectrometric determination of
    decabromodiphenyl oxide in industrial sewage. Ind Lab, 53: 289-290.

    Kalk (1982) [CFK Bromkal(R) - fire protection equipment]. Cologne,
    Kalk Chemical Factory (Information sheet 3000-7/82) (in German).

    Kitchin KT, Brown JL, & Kulkarni P (1992) Predictive assay for rodent
    carcinogenicity using  in vivo biochemical parameters: operational
    characteristics and complementarity. Mutat Res, 266: 253-272.

    Klusmeier W, Voegler P, Ohrbach KH, Weber H, & Kettrup A (1988)
    Thermal decomposition of decabromodiphenyl ether. J Anal Appl
    Pyrolysis, 13: 277-285.

    Kociba RJ (undated) Comparative biologic activity and toxicity of
    brominated derivatives of diphenylether (oxide). (Unpublished report
    submitted to WHO by BFRIP).

    Kociba RJ, Frauson LO, Humiston CG, Norris JM, Wade CE, Lisowe RW,
    Quast IF, Jersey GC, & Jewett GL (1975a) Results of a two-year dietary
    feeding study with decabromodiphenyl oxide (DBDPO) in rats. Midland,
    Michigan, Dow Chemical Company (Unpublished report submitted to WHO by
    BFRIP).

    Kociba RJ, Frauson LO, Humiston CG, Norris JM, Wade CE, Lisowe RW,
    Quast JF, Jersey GC, & Jewett GL (1975b) Results of a two-year dietary
    feeding study with decabromodiphenyl oxide (DBDPO) in rats. Combust
    Toxicol, 2: 267-285.

    De Kok JJ, De Kok A, Brinkman UATh, & Kok RM (1977) Analysis of
    polybrominated biphenyls. J Chromatogr, 142: 367-383.

    De Kok JJ, De Kok A, & Brinkman UATh (1979) Analysis of polybrominated
    aromatic ethers. J Chromatogr, 171: 269-278.

    Kopp A (1990) [Documentation on fire-proofing agents containing
    bromine.] Bonn, Ministry of Environment, Nature Conservation and
    Nuclear Safety (Report to the European Economic Community, Brussels)
    (in German).

    Koster P, Debets FMH, & Strik JJTWA (1980) Porphyrinogenic action of
    fire retardants. Bull Environ Contain Toxicol, 25:313-315.

    Kraus HW (1990) Polybrominated dibenzodioxines and dibenzofurans
    (PBDDs/PBDFs) from flame retardants containing bromine. Bonn, Ministry
    for Environment, Nature Conservation and Nuclear Safety (Report to the
    Organisation for Economic Co-operation and Development, Paris).

    Kruger C (1988) [Polybrominated biphenyls and polybrominated diphenyl
    ethers detection and quantitation in selected foods.] Munster,
    University of Munster (Thesis) (in German).

    Kuehl DW, Haebler R, & Potter C (1991) Chemical residues in dolphins
    from the U.S. Atlantic coast including Atlantic bottlenose obtained
    during the 1987/88 mass mortality. Chemosphere, 22(11): 1071-1084.

    Lahaniatis ES, Bergheim W, & Rainer C (1989) Hazardous halogenated
    substances formed during combustion processes. Toxicol Environ Chem,
    20-21: 501-506.

    Lahaniatis ES, Bergheim W, & Bieniek D (1991) Formation of
    2,3,7,8-tetrabromodibenzodioxin and -furan by thermolysis of polymers
    containing brominated flame retardants. Toxicol Environ Chem,
    31/32: 521-526.

    Lahl U, Wilken M, & Wiebe A (1991) [Polybrominated diphenyl ethers in
    waste incineration.] Mull Abfall, 23:83-87 (in German).

    Larsen ER (1978) Flame retardants. Halogenated fire retardants. In:
    Mark HF, Othmer DF, Overberger CG, Seaborg GT, & Grayson M ed.
    Kirk-Othmer encyclopedia of chemical technology, 3rd ed. New York,
    Chichester, Brisbane, Toronto, John Wiley and Sons, vol 10,
    pp 373-395.

    Leblanc RB (1979) What's available for FR textiles. Text Ind,
    143: 78-83.

    Leblanc GA (1980) Acute toxicity of priority pollutants to water flea
     (Daphnia magna). Bull Environ Contam Toxicol, 24(5): 684-691.

    Leung HW, Murray FJ, & Paustenbach DJ (1988) A proposed occupational
    exposure limit for 2,3,7,8-tetrachlorodibenzo- p-dioxin. Am Ind Hyg
    Assoc J, 49(9): 466-474.

    Luijk R & Govers HAJ (1992) The formation of polybrominated
    dibenzo- p-dioxins (PBDDs) and dibenzofurans (PBDFs) during pyrolysis
    of polymer blends containing brominated flame retardants. Chemosphere,
    25(3): 361-374.

    McAllister DL & Ariano JIM (1982) DE-71/DE-60F. Determination of
    bromination level and aromatic phosphate ester concentration.
    Analytical method No. QCS-82-25. West Lafayette, Indiana, Great Lakes
    Chemical Corporation (Report submitted to WHO by BFRIP).

    McAllister DL, Mazac CJ, Gorsich R, Freiberg M, & Tondeur Y (1990)
    Analysis of polymers containing brominated diphenyl ethers as flame
    retardants after molding under various conditions. Chemospbere,
    20(10-12): 1537-1541.

    McAllister DL (1991) Letter of Great Lakes Chemical Corporation, West
    Lafayette to the IPCS/WHO, dated November 25, 1991.

    MacKay D & Leinonen PJ (1975) Rate of evaporation of low-solubility
    contaminants from water bodies to the atmosphere. Environ Sci Technol,
    9(13): 1178-1180.

    McMahon LW (1983) Organic priority pollutants in wastewater. In:
    Proceedings of the 1982 UCC-ND/GATT Environmental Protection Seminar,
    April, 5-7, 1982. Oak Ridge, TN. Oak Ridge National Laboratory/Union
    Carbide Corp. US (DOE Contract No. W-7405-eng-26) (US EPA, 1986).

    Mallory VT, Naismith RW, & Matthews RJ (1986) Primary eye irritation
    (PH 421-ET-010-86) Saytex 102. Baton Rouge, Louisiana, Ethyl
    Corporation (Unpublished report submitted to WHO by BFRIP).

    Naismith RW & Matthews RJ (1981) Assay of comedogenicity in the rabbit
    ear (PH 425-ET-001-81) Saytex 102. Baton Rouge, Louisiana, Ethyl
    Corporation (Unpublished report submitted to WHO by BFRIP).

    Neupert M, Weis H, Thies J, & Stock B (1989) Analytical procedures in
    connection with acute animal toxicity studies. II. Pyrolysis products
    obtained from an ABS copolymer containing octabromodiphenylether as a
    flame retardant. Chemosphere, 19(16): 219-224.

    Noguchi Y, Noda E, Toyoshima K, & Mitsui Toatsu Chemicals Inc. (1977)
    Photostabilized polybromobiphenyl ethers. Japan Kokai 77 07,932,
    January 21, 1977. (as reported in Chem. Abstr. 87: 134511x) (US EPA,
    1986).

    Norris JM (1971) Decabromodiphenyloxide solids from mother liquor
    (waste tars). Midland, Michigan, Dow Chemical Company (Unpublished
    report TOX-No. T2.TX-1767-1, submitted to WHO by BFRIP).

    Norris JM, Ehrmantraut JW, Gibbons CL, Kociba RJ, Schwetz BA, Rose JQ,
    Humiston CG, Jewett GL, Crummett WB, Gehring PJ, Tirsell JB, & Brosier
    JS (1973) Toxicological and environmental factors involved in the
    selection of decabromodiphenyl oxide as a fire retardant chemical.
    Appl Polymer Symp, 22: 195-219.

    Norris JM, Ehrmantraut JW, Gibbons CL, Kociba RJ, Schwetz BA, Rose JQ,
    Humiston CO, Jewett GL, Crummett WB, Gehring Pl, Tirsell JB, & Brosier
    JS (1974) Toxicological and environmental factors involved in the
    selection of decabromodiphenyloxide as a fire retardant chemical.
    J Fire Flamm Combust Toxicol, 1, 52-77.

    Norris JM, Ehrmantraut JW, Kociba RJ, Schwetz BA, Rose JQ, Humiston
    CO, Jewett OL, Crummet WB, Gehring PJ, Tirsell JB, & Brosier JS
    (1975a) Evaluation of deca-bromodiphenyloxide as a flame-retardant
    chemical. Chem Hum Health Environ, 1: 100-116.

    Norris JM, Kociba RJ, Humiston CG, & Gehring PJ (1975b) The toxicity
    of deca-bromodiphenyloxide and octabromodiphenyl as determined by
    subacute and chronic dietary feeding studies in rats. Toxicol Appl
    Pharmacol, 33(1): 170 (abstract).

    Norris JM, Kociba RJ, Schwetz BA, Rose JQ, Humiston CG, Jewett GL,
    Gehring PJ, & Mailhes JB (1975c) Toxicology of octabromodiphenyl and
    decabromodiphenyloxide. Environ Health Perspect, 11: 153-161.

    NTP (1986) Toxicology and carcinogenesis studies of decabromodiphenyl
    oxide (CAS No. 1163-19-5) in F344/N rats and B6C3F1 mice (feed
    studies). Research Triangle Park, North Carolina, US Department of
    Health and Human Services, National Toxicology Program (NTP Technical
    Report Series No. 309).

    Nylund K, Asplurid L, Jansson B, Jonsson P, Litzen K, & Sellström U
    (1992) Analysis of some polyhalogenated organic pollutants in sediment
    and sewage sludge. Chemosphere, 24(12): 1721-1730.

    Oberg T & Bergstrom J (1990) Bromine and waste incineration - An
    environmental risk? In: Hutzinger O & Fiedler H ed. Dioxin'90.
    EPRI-Seminar. Tenth International Symposium on Chlorinated Dioxins and
    Related Compounds. Volume 2: Organo-halogenated compounds (short
    papers). Bayreuth, Germany, Ecoinforma Press, pp 339-342.

    Oberg T, Warman K, & Bergström J (1987) Brominated aromatics from
    combustion. Chemosphere, 16(10-12): 2451-2465.

    OECD (1991) Co-operation on existing chemicals: Risk reductions. Lead
    country report on brominated flame retardants. Sixteenth Joint Meeting
    of the Chemicals Group and Management Committee, 28-30 May 1991.
    Paris, Organisation for Economic Cooperation and Development (Report
    ENV/MC/CHEM (91)7).

    Pijnenburg AMCM & Everts JW (1991) [Flame retardams: Occurrence and
    toxicity.] The Hague, Ministry of Transport and Public Works (Note
    No. GWAO-91.001) (in Dutch).

    Pijnenburg AMCM, Everts JW, De Boer J, & Boon JP (1992) Polyhrominated
    biphenyl (PBB) and diphenylether (PBDE) flame retardants: Analysis,
    toxicity and occurrence in aquatic environments. Manuscript for
    discussion in 1992 Annual Meeting of the ICES Marine Chemistry Working
    Group (MCWG) and the Working Group on Biological Effects of
    Contaminants (WGBEC). The Hague, Ministry of Transport and Public
    Works (Unpublished report).

    Pinkerton MN, Kociba RJ, Petrella RV, McAllister DL, Willis ML, Fulfs
    JC, Thoma H, & Hutzinger O (1989) A preliminary report on the
    investigation of the comparative toxicity of combustion products of
    high impact polystyrene with and without decabromodiphenyloxide/
    antimony trioxide as a flame retardant using 2,3,7,8-tetrabromo-
    dibenzo- p-dioxin and 2,3,7,8-tetrabromodibenzofuran as positive
    controls. Chemosphere, 18(1-6): 1243-1249.

    Plumb RH Jr (1991) The occurrence of Appendix IX organic constituents
    in disposal site ground water. Groundw Monit Rev, 11(2): 157-164.

    Rampy LW (1971-1974) Chloracne studies on DBDPO and DBDPO mother
    liquor. A series of working protocols with results from the Chemical
    Biology Research Department of Dow Chemical USA, Midland, Michigan
    (The work was carried out mainly by Rampy alone or with co-workers in
    the period 1971-1974) (Report submitted to WHO by BFRIP).

    Ranken PF, Ricks GM, Lynam DR, & Ariano JM (1990) Is watching
    television toxic? BFRIP-sponsored study on the emission of PBDDs/PBDFs
    from operating television sets. In: Hutzinger O & Fiedler H ed.
    Dioxin'90. EPRI-Seminar. Tenth International Symposium on Chlorinated
    Dioxins and Related Compounds. Volume 2: Organohalogenated compounds
    (short papers). Bayreuth, Germany, Ecoinforma Press, pp 343-346.

    Remmers JC, Breen JJ, Schwemberger J, Stanley JS, Cramer PH, &
    Thornburg KR (1990) Mass spectral confirmat!on of chlorinated and
    brominated diphenyl ethers in human adipose tissues. In: Hutzinger O &
    Fiedler H ed. Dioxin'90. EPRI-Seminar. Tenth International Symposium
    on Chlorinated Dioxins and Related Compounds. Volume 2:
    Organohalogenated compounds (short papers). Bayreuth, Germany,
    Ecoinforma Press, pp 347-350.

    Riggs KB, Pitts GE, White JS, Mitchum RK, Reuther JJ, & Glatz JA
    (1990) Polybrominated dibenzo- p-dioxin and polybrominated
    dibenzofuran emissions from incineration of flame-retarded resins in a
    simulated municipal waste incinerator. In: Hutzinger O & Fiedler H ed.
    Dioxin'90. EPRI-Seminar. Tenth International Symposium on Chlorinated
    Dioxins and Related Compounds. Volume 2: Organohalogenated compounds
    (short papers). Bayreuth, Germany, Ecoinforma Press, pp 351-356.

    Rogers J & Hill JT (1980) Final report. Determination of
    decabromodiphenyl oxide (DBDPO) in rat livers. Vienna, Virginia,
    Hazleton Laboratories America, Inc. (Unpublished report to Tracor
    Jitco, Rockville, Maryland, submitted to WHO by BFRIP).

    Rutter HA & Machotka S (1979) Final Report. Decabromodiphenyloxide:
    13-week sub-chronic feeding study -- mice. Vienna, Virginia, Hazleton
    Laboratories America, Inc. (Unpublished report to Tracor Jitco,
    Rockville, Maryland, submitted to WHO by BFRIP).

    Schwetz BA, Smith FA, Nitschke KD, Humiston CG, Jersey GC, & Kociba RJ
    (1975) Results of a reproduction study in rats maintained on diets
    containing decabromodiphenyloxide. Midland, Michigan, Dow Chemical
    Company (Unpublished report No. HET K47298-(14), submitted to WHO by
    BFRIP).

    Sellström U, Andersson R, Asplund L, Jansson B, Jonsson P, Litzen K,
    Nylund K, Uvemo U-B, & Wideqvist U (1990b) Anthropogenic brominated
    aromatics in the Swedish environment. In: Freij L ed. Proceedings of
    the Workshop on Brominated Aromatic Flame Retardants, Skokloster,
    Sweden, 24-26 October 1989. Solna, National Chemicals Inspectorate
    CKEMI), pp 73-78.

    Sellström U, Jansson B, Ionsson P, Nylund K, Odsjö T, & Olsson M
    (1990a) Anthropogenic brominated aromatics in the Swedish environment.
    In: Hutzinger O & Fiedler H ed. Dioxin'90. EPRI-Seminar. Tenth
    International Symposium on Chlorinated Dioxins and Related Compounds.
    Volume 2: Organohalogenated compounds (short papers). Bayreuth,
    Germany, Ecoinforma Press, pp 357-360.

    Sellström U, Jansson B, Kierkegaard A, & De Wit C (1993a)
    Polybrominated diphenyl ethers (PBDE) in biological samples from the
    Swedish environment. Chemosphere, 26(9): 1703-1718.

    Sellström U, Kierkegaard A, De Wit C, Jansson B, & Olsson M (1993b)
    Time trend studies of polybrominated diphenyl ethers (PBDE) in
    biological material from the Swedish environment. Paper presented at
    Dioxin'93, Vienna, 1 September 1993.

    Shoichet A & Ehrlich K (1977) Mutagenicity testing of HFO 102.
    (Unpublished proprietary report from Gulf South Research Institute,
    New Orleans, Louisiana to Hexel Fine Organics (Report submitted to WHO
    by BFRIP).

    Sovocool GW, Donnelly JR, Grange All, Simmons RD, & Munslow WD (1990)
    Brominated dioxins and other bromoaromatics in plastic pyrolysates.
    In: Hutzinger O & Fiedler H ed. Dioxin'90. EPRI-Seminar. Tenth
    International Symposium on Chlorinated Dioxins and Related Compounds.
    Volume 2: Organohalogenated compounds (short papers). Bayreuth,
    Germany, Ecoinforma Press, pp 365-368.

    Sparschu GL, Kociba RJ, & Clashman A (1971) Results of 30 day rat
    dietary feeding studies on octabromobiphenyl SA-1902 and
    decabromodiphenyl oxide SA-1892.1. Midland, Michigan, Dow Chemical
    Company (Unpublished report submitted to WHO by BFRIP).

    Stafford CJ (1983) Halogenated diphenylethers identified in avian
    tissues and eggs by GC/MS. Chemosphere, 12(11/12): 1487-1495.

    Stanley JS, Cramer PH, Thornburg KR, Remmers JC, Breen JJ, &
    Schwemberger J (1991) Mass spectral confirmation of chlorinated and
    brominated diphenylethers in human adipose tissues. Chemosphere,
    23(8-10): 1185-1195.

    Striebich RC, Rubey WA, Tirey DA, & Dellinger B (1991) High
    temperature degradation of polybrominated flame retardant materials.
    Chemosphere, 23(8-10): 1197-1204.

    Sundström G & Hutzinger O (1976) Environmental chemistry of flame
    retardants. V. The composition of Bromkal (R) 70-5 DE -- A
    pentabromodiphenyl ether preparation. Chemosphere, 3: 187-190.

    Tabak HH, Quave SA, Mashni Cl, & Barth EF (1981) Biodegradability
    studies with organic priority pollutant compounds. J Water Pollut
    Control Fed, 53: 1503-1518.

    Tabor TE & Bergman S (1975) Decabromodiphenyl oxide. A new fire
    retardant additive for plastics. In: Fire retardants. Proceedings of
    1974 International Symposium on Flammability and Fire Retardants,
    Cornwall, Ontario, 1-2 May 1974. Westport, Connecticut, Technomic
    Publishing, pp 162-179.

    Takase I, Omori T, & Midona Y (1986) Microbial degradation products
    from biphenyl-related compounds. Agric Biol Chem, 50(3): 681-686.

    Theiss JC, Stoner GD, Shimkin MB, & Weisburger EK (1977) Test for
    carcinogenicity of organic contaminants of United States drinking
    waters by pulmonary tumor response in strain A mice. Cancer Res,
    37: 2717-2720.

    Thoma H & Hutzinger O (1987) Pyrolysis and GC/MS-analysis of
    brominated flame retardants in on-line operation. Chemopshere,
    16(6): 1353-1360.

    Thoma H & Hutzinger O (1989) Pyrolysis and GC/MS-analysis of
    brominated flame retardants in on-line operation. Chemosphere,
    18(5): 1047-1050.

    Thoma H, Hauschulz G, Knorr E, & Hutzinger O (1987a) Polybrominated
    dibenzofurans (PBDF) and dibenzodioxins (PBDD) from the pyrolysis of
    neat brominated diphenylethers, biphenyls and plastic mixtures of
    these compounds. Chemosphere, 16(1): 277-285.

    Thoma H, Hauschulz G, & Hutzinger O (1987b) PVC-induced
    chlorine-bromine exchange in the pyrolysis of polybrominated diphenyl
    ethers, -biphenyls, dibenzodioxins and dibenzofurans. Chemosphere,
    16(1): 297-307.

    Timmons LL & Brown RD (1988) Analysis of the brominated fire retardant
    decabromdiphenyloxide for low and trace levels impurities.
    Chemosphere, 17: 217-234.

    UK DOE (1992) Risk benefit analysis of hazardous chemicals. London, UK
    Department of Environment.

    Ulsamer AG, Osterberg RE, & McLaughlin J Jr (1980) Flame retardant
    chemicals in textiles. Clin Toxicol, 17(1): 101-131.

    UMWELTBUNDESAMT (1989) Status report: Polybrominated dibenzodioxins
    and polybrominated dibenzofurans. Berlin.

    US EPA (1978) Chemical screening. Initial evaluations of substantial
    risk notices: section 8(e), January 1, 1977 to June 39, 1979.
    Washington, DC, US Environmental Protection Agency, Office of
    Pesticides and Toxic Substances, Office of Testing and Evaluation,
    vol I, pp 39-40 (EPA 560/11-80-008).

    US EPA (1984) Health and environmental effects profile for brominated
    diphenyl ethers. Cincinnati, Ohio, US Environmental Protection Agency,
    Environmental Criteria and Assessment Office CEPA/600/X-84/133).

    US EPA (1986) Brominated diphenylethers. Chemical hazard information
    profile. Washington, DC, US Environmental Protection Agency.

    US EPA (1988) Information review: Brominated diphenyl ethers.
    Washington, DC, US Environmental Protection Agency, TSCA, Interagency
    Testing Committee (Report No. IR-516).

    US EPA (1989) Letter from Director Office of Toxic Substances,
    Washington, to Great Lakes Chemical Corporation, dated July 27, 1989.

    US Testing Company (1985) Determination of vapour pressure and melting
    point. Chemical Services Division. Hoboken, New Jersey. Letter to
    Great Lakes Chemical Corporation. 7 October 1985 (Report submitted to
    WHO by BFRIP).

    Vinci TM & Craig DK (1988) Characterization of fume components
    generated during the extrusion of flame-retarded polyester resins.
    Columbus, Ohio, Battelle (Unpublished report to GE Plastics, Mt.
    Vernon, Indiana, submitted to WHO by BFRIP).

    Von Meyerinck L, Hufnagel B, Schmoldt A, & Benthe HF (1990) Induction
    of rat liver microsomal cytochrome P-450 by the pentabromodiphenyl
    ether Bromkal 70 and half lives of its components in the adipose
    tissue. Toxicology, 61: 259-274.

    Walsh GE, Yoder MI, McClaughlin LL, & Lores EM (1987) Responses of
    marine unicellular algae to brominated organic compounds in six growth
    media. Ecotoxicol Environ Saf, 14: 215-222.

    Watanabe I (1987) Text from undated slide presentation.

    Watanabe I & Tatsukawa R (1987) Formation of brominated dibenzofurans
    from the photolysis of flame retardant decabromodiphenyl ether in
    hexane solution by UV and sunlight. Bull Environ Contain Toxicol,
    39: 953-959.

    Watanabe I & Tatsukawa R (1990) Anthropogenic brominated aromatics in
    the Japanese environment. In: Freij L ed. Proceedings of the Workshop
    on Brominated Aromatic Flame Retardants, Skoldoster, Sweden, 24-26
    October 1989. Solna, National Chemicals Inspectorate (KEMI), pp 63-71.

    Watanabe I, Kashimoto T, & Tatsukawa R (1986) Confirmation of the
    presence of the flame retardant decabromodiphenyl ether in river
    sediment from Osaka, Japan. Bull Environ Contam Toxicol, 36: 839-842.

    Watanabe I, Kashimoto T, Kawano M, & Tatsukawa R (1987a) A study of
    organic bound halogens in human adipose tissue, marine organisms and
    sediment by neutro-activation and gas chromatographic analysis.
    Chemosphere, 16(4): 849-857.

    Watanabe I, Kashimoto T, & Tatsukawa R (1987b) Polybrominated
    biphenylethers in marine fish, shellfish and river and marine
    sediments in Japan. Chemopshere, 16(10/12): 2389-2396.

    Watanabe I, Kawano M, Wang Y, Chen Y, & Tatsukawa R (1992)
    Polybrominated dibenzo- p-dioxins (PBDDs) and -dibenzofurans (PBDFs)
    in atmospheric air in Taiwan and Japan. In: Dioxin'92. Twelfth
    International Symposium on Dioxins and Related Compounds, Tampere,
    Finland, 24-28 August 1992. Organohalogen Compounds Volume 9: Sources
    of exposure.

    Watanabe I, Kawano M, & Tatsukawa R (undated) Consumption trend and
    environmental research on brominated flame retardants in Japan and the
    formation of polyhalogenated dibenzofurans at the metal reclamation
    factory. Document distributed at the OECD Workshop on the Risk
    Reduction of Brominated Flame Retardants, Neuchatel, 1993.

    WHO (1989) Environmental Health Criteria 88: Polychlorinated
    dibenzo- p-dioxins and bibenzofurans. Geneva, World Health
    Organization.

    WHO (1994) Environmental Health Criteria 152: Polybrominated
    biphenyls. Geneva, World Health Organization.

    Yagi O & Sudo R (1980) Degradation of polychlorinated biphenyls by
    microorganisms. JWPCF 52(5), 1035-1043 and US EPA, 1986.

    Yamamoto K, Mori Y, Uehira S, Tanaka T, Koyama T, Katuyama K,
    Taniguchi Y, & Sakamoto T (1991) Content of presence of the flame
    retardant decabromodiphenyl ether in Kino river Basin. Wakayama-ken
    Eisei Kogai Kenkyu Senta Nenpo, 37:116-122.

    Zacharewski T, Harris M, Safe S, Thoma H, & Hutzinger O (1988)
    Applications of the  in vitro aryl hydrocarbon hydroxylase induction
    assay for determining "2,3,7,8-tetrachlorodibenzo- p-dioxin
    equivalents": pyrolyzed brominated flame retardants. Toxicology,
    51: 177-189.

    Zier B, Lenoir D, Lahaniatis ES, & Kettrup A (1991) Surface catalyzed
    halogenation-dehalogenation reactions of aromatic bromine compounds
    adsorbed on fly ash. Chemosphere, 22(12): 1121-1129.

    Zober MA, Ott MG, Pfipke O, Senft K, & Germann C (1992) Morbidity
    study of extruder personnel with potential exposure to brominated
    dioxins and furans. I. Results of blood monitoring and immunological
    tests. Br J Ind Med, 49: 532-544.

    Zogorski JS (1984) Experience in monitoring domestic water sources and
    process waters for trace organics. J Environ Sci Health,
    A19(2): 233-249.

    Van Zorge JA, Bruijnes C, Van den Berg EV, & Sprong W (1992)
    Brominated flame retardants: Polybrominated biphenyls (PBBs) and
    polybrominated diphenyloxides (PBDOs). OECD Cooperative risk reduction
    activities for certain dangerous chemicals, Paris. Fifth draft, May
    26th, 1992.

    Zweidinger RA, Cooper SD, Erickson MD, Michael LC, & Pellizzari ED
    (1977) Sampling and analysis for semivolatile brominated organics in
    ambient air. In: Schuetzle D ed. Monitoring toxic substances.
    Washington, DC, American Chemical Society, pp 217-231 (ACS Symposium
    Series No. 94).

    Zweidinger RA, Cooper SD, & Pellizzari ED (1978) Identification and
    quantitation of brominated fire retardants. In: Measurement of organic
    pollutants in water and waste water. Symposium of the American Society
    for Testing and Materials, Denver, Colorado, 19-20 June 1978.
    Philadelphia, Pennsylvania, American Society for Testing and
    Materials, pp 234-250 (ASTM Technical Publication No. 686).

    RESUME ET EVALUATION, CONCLUSIONS ET RECOMMANDATIONS

    DECABROMODIPHENYLETHER

    1  Résumé et évaluation

    1.1  Identité, propriétés physiques et chimiques

        Le DeBDE du commerce se caractérise par une pureté de 97 à 98%, et
    une teneur en nona- et/ou octabromodiphényléthers de 0,3 à 3,0%. Le
    nonabromodiphényléther (NBDE) en est l'impureté principale.
    Contrairement aux autres polybromo-diphényléthers, le DeBDE n'a qu'un
    isomère.

        Le point de fusion du DeBDE est d'environ 300°C et il se décompose
    au dessus de 400°C. Sa solubilité dans l'eau est de 20-30/µg/litre et
    le logarithme de son coefficient de partage  n-octanol/eau est
    supérieur à 5. Sa tension de vapeur est <10-6 mmHg à 20°C.

    1.2  Production et usages

        De tous les bromodiphényléthers (mono- à déca-) le
    décabromodiphényléther est, de par sa production et son usage, le plus
    important du point de vue commercial.

        On le produit depuis la fin des années 70 à un degré de plus en
    plus élevé de pureté. La production mondiale de DeBDE est d'environ
    30 000 tonnes par an. On l'utilise comme retardateur de flamme dans de
    nombreuses matières plastiques, notamment dans le polystyrène choc,
    ainsi que pour le traitement des tissus d'ameublement, ou encore des
    textiles utilisés en sellerie automobile ou pour la confection de
    tentes.

    1.3  Transport, distribution et transformation dans l'environnement

        En solution dans des solvants organiques, le DeBDE subit une
    photodécomposition sous l'influence du rayonnement ultra-violet ou de
    la lumière solaire; cette réaction conduit à la formation de
    bromodiphényléthers moins substitués et de bromodibenzofuranes. Cette
    photodécomposition se produit également, quoique dans une moindre
    mesure, en solution aqueuse, sous l'action du rayonnement solaire; on
    ne retrouve plus alors d'homologues inférieurs du DeBDE ni de
    bromodibenzofuranes.

        Les quantités de DeBDE que l'on peut extraire des polymères sont
    inférieures à la limite de détection ou très proches de cette limite,
    selon le type de polymère et le solvant d'extraction.

        Du fait que sa solubilité dans l'eau et sa tension de vapeur sont
    très faibles, le DeBDE est vraisemblablement transporté
    essentiellement par adsorption sur des particules. Il est persistant
    et s'accumule probablement dans les sédiments et le sol.

        On en dispose d'aucune donnée sur sa biodisponibilité à partir des
    sédiments et du sol. Une étude sur des truites arc-en-ciel n'a pas
    révélé de bioaccumulation dans la chair, la peau ou les viscères de
    ces poissons, sur une période de 48 heures. Il est improbable que le
    DeBDE subisse une bioaccumulation en raison de sa masse moléculaire
    relative élevée.

        Les rebuts qui contiennent du DeBDE commercial finissent dans les
    décharges contrôlées ou les incinérateurs. Il se peut que du DeBDE
    s'échappe de ces décharges par lessivage. Le brûlage sur les décharges
    ou une incinération inefficace peuvent conduire à la formation de
    polybromodibenzofuranes (PBDF) et d'un mélange d'halogénodi-
    benzofuranes et d'halogénodibenzodioxines. Les produits qui
    contiennent du DeBDE commercial peuvent contribuer à ces émissions.

        La pyrolyse, en présence d'oxygène, de DeBDE commercial et de
    polymères contenant de ce produit (polystyrène choc, PBT,
    polypropylène industriel) produit des polybromodibenzofuranes et en
    moindre quantités, des polybromodibenzodioxines. C'est aux
    températures de 400 à 500°C que les PBDF sont produits en quantités
    maximales mais ils peuvent également se former à des températures
    allant jusqu'à 800°C et Sb2O3 en catalytise la formation.

        La formation des PBDF et des PBDD ainsi que leurs proportions
    respectives, dépendent de la température, de la teneur en oxygène et
    de la durée de la pyrolyse. En l'absence d'oxygène, il se forme
    principalement des polybromobenzènes et des polybromonaphtalènes.

    1.4  Concentrations dans l'environnement et exposition humaine

        On a trouvé du DeBDE dans l'air à proximité d'unités de
    production, à des concentrations allant jusqu'à 25 µg/m3. En
    revanche, on n'a pas décelé de DeBDE dans des échantillons d'eau
    prélevés au Japon entre 1977 et 1991. Cependant, on en a trouvé dans
    des sédiments de rivières, également prélevés au Japon au cours de la
    même période, à des déconcentrations allant jusqu'à environ 12 mg/kg
    de poids sec. On a également décelé la présence (jusqu'à 1 g/kg) de
    DeBDE dans des sédiments de cours d'eau aux Etats-Unis, à proximité
    d'une unité de production. On n'a pas décelé de DeBDE dans des
    échantillons de poissons recueillis au Japon, mais, dans un
    échantillon de moules on en a trouvé à des teneurs juste supérieures
    au seuil de détection. Le produit n'a pas été décelé dans des
    échantillons de tissus adipeux humains prélevés au Japon; en revanche,
    aux Etats-Unis, on en a trouvé dans trois échantillons sur cinq du
    même type de tissus.

        Au cours de la production de DeBDE et de son adjonction aux
    polymères, il peut y avoir exposition humaine. En revanche, cette
    exposition est négligeable pour la population générale.

        En cherchant à déterminer l'exposition professionnelle aux
    produits de décomposition du DeBDE lors de sa fabrication et de son
    incorporation par extrusion à des polymères, on a constaté la présence
    de fortes concentrations de PBDF dans des échantillons d'air prélevés
    au niveau de la filière de l'extrudeuse. Les concentrations étaient
    moindres dans l'air de l'atelier. Des PBDF ont été également retrouvés
    dans des échantillons obtenus lors de l'essuyage. Moyennant une bonne
    technique de travail, on peut réduire l'exposition professionnelle aux
    PBDF.

        L'exposition de la population générale aux PBDF présents comme
    impuretés dans des polymères contenant des retardateurs de flamme, est
    vraisemblablement négligeable.

    1.5  Cinétique et métabolisme chez les animaux de laboratoire et
         l'homme

        Le DeBDE est faiblement résorbé dans les voies digestives et après
    injection, il est rapidement excrété.

        D'après les résultats d'études de métabolisme chez le rat, au
    moyen de DeBDE marqué au 14C, la demi-vie d'élimination de ce composé
    serait inférieure à 24 heures et la principale voie d'élimination
    après ingestion, serait la voie fécale. On n'a pas constaté la
    présence d'une activité appréciable de 14C (moins de 1%) dans l'urine
    ou l'air expiré.

        Des rats à qui l'on avait administré pendant des périodes allant
    jusqu'à deux ans, une dose quotidienne de 0,1 mg/kg de poids corporel
    de ce composé, n'ont présenté aucun accumulation de DeBDE dans leur
    sérum, leurs reins, leurs muscles ou leurs testicules, d'après le
    dosage du brome total. L'accumulation du brome dans le foie a atteint
    un palier au bout de 30 jours et l'élimination s'est effectuée dans
    les 10 jours suivants le traitement. Après 180 jours, la concentration
    de brome dans le foie n'était pas plus élevée chez les rats traités
    que chez les rats témoins. Dans les tissus adipeux, on a noté une
    faible accumulation de brome total, qui a subsisté après 90 jours de
    nourriture sans DeBDE; on ignore quelle est la nature du "brome"
    retenu. Etant donné que le DeBDE ne représentait que 77% du mélange
    commercial utilisé, ce "brome" pourrait provenir du NBDE ou de l'OBDE.

    1.6  Effets sur les mammifères de laboratoire et les systèmes d'épreuve
         in vitro

        Pour les animaux de laboratoire, la toxicité aiguë du DeBDE est
    faible. Le produit n'est pas irritant pour la peau ou les yeux des
    lapins. Il ne provoque pas de chloracné sur la peau des lapins et n'a
    pas d'effet sensibilisateur sur la peau humaine.

        Les produits de combustion du polystyrène contenant un retardateur
    de flamme à base de DeBDE et de Sb2O3 ont été étudiés afin d'en
    déterminer la toxicité aiguë et la comédogénicité. Chez le rat, la
    DL50 par voie orale de la suie et du résidu de carbonisation était
    >2000 mg/kg de poids corporel.

        Lors d'études de toxicité à long terme effectuées sur des rats et
    des souris, du DeBDe (pureté >97%) a été administré aux animaux mêlé
    à leur nourriture aux doses de 100 g/kg de nourriture (4 semaines) ou
    50g/kg (13 semaines, soit l'équivalent de 2500 mg/kg de poids corporel
    en ce qui concerne le rat) sans produire d'effets nocifs. Une étude de
    reproduction portant sur une génération de rats n'a pas révélé
    d'effets nocifs aux doses de 100 mg/kg de poids corporel. Le DeBDE n'a
    pas provoqué d'effets tératogènes chez des foetus de rats ayant reçu
    une dose de 100 mg/kg de poids corporel. A la dose de 1000 mg/kg de
    poids corporel, on a observé des malformations, par exemple un retard
    d'ossification. Soumis à un certain nombre d'épreuves, le DeBDE ne
    s'est pas révélé mutagène.

        Lors d'une étude de cancérogénicité sur des rats et des souris, du
    DeBDE (pureté 94-99%) a été administré, mêlé à leur nourriture, à des
    doses allant jusqu'à 50 g/kg. On a observé une augmentation dans
    l'incidence des adénomes (mais pas des carcinomes) au niveau du foie
    chez les rats mâles qui en avaient reçu 25 g/kg et chez les femelles
    qui en avaient reçu 50 g/kg. Chez les souris mâles, on a observé une
    augmentation de l'incidence des adénomes et/ou des carcinomes
    hépatocellulaires (les deux ensemble) à la dose de 25 g/kg et une
    augmentation des adénomes et des cancers (les deux ensemble)
    médullaires de la thyroïde à ces deux doses. Chez les souris femelles,
    on n'a pas relevé d'augmentation dans l'incidence des tumeurs. C'est
    uniquement aux doses de 25 à 50 g de DeBDE/kg de nourriture que chez
    les rats mâles et femelles d'une part, et chez les souris mâles
    d'autre part, on a constaté l'existence de signes équivoques de
    cancérogénicité. Etant donné que les résultats de toutes les épreuves
    de mutagénicité sont restés négatifs, on peut en conclure que le DeBDE
    n'est pas un cancérogène génotoxique. Le CIRC (1990) est parvenu à la
    conclusion que les preuves d'une cancérogénicité du DeBDE chez les
    animaux de laboratoire sont limitées. Du fait des très fortes doses
    utilisées dans ces études, de l'absence de génotoxicité et des
    éléments de preuve très minimes en faveur d'une cancérogénicité de ce
    composé, on peut conclure que le DeBDE, aux taux d'exposition actuels,
    ne présente pas de risque cancérogène pour l'homme.

    1.7  Effets sur l'homme

        Chez des sujets humains exposés à du DeBDE lors d'une épreuve de
    sensibilisation, on n'a noté aucun signe de sensibilisation cutanée.

        Une étude de morbidité sur des ouvriers qui procédaient à
    l'extrusion de polybutylène-téréphtalate contenant du DeBDE (avec par
    conséquent un risque potentiel d'exposition aux PBDD et aux PBDF
    pendant 13 ans) n'a pas révélé le moindre effet délétère, malgré la
    présence dans leur sang de 2,3,7,8-TeBDF et de 2,3,7,8-TeBDD. Les
    études immunologiques effectuées ont montré que le système immunitaire
    des personnes exposées n'avait pas souffert au cours de ces 13 années.

    1.8  Effets sur les autres êtres vivants au laboratoire et dans leur
         milieu naturel

        La CE50 relative à la croissance de trois algues marines
    unicellulaires s'est révélée supérieure à 1 mg de DeBDE par litre. On
    ne dispose d'aucune autre information concernant les effets du DeBDE
    sur les autres êtres vivants au laboratoire ou dans leur milieu
    naturel.

    2  Conclusions

    2.1  DeBDE

        Le DeBDE est largement utilisé comme retardateur de flamme dans
    les polymères. S'il entre en contact avec la population générale,
    c'est par l'intermédiaire des produits fabriqués à partir de ces
    polymères. L'exposition est très faible étant donné que le DeBDE n'est
    pas facile à extraire de ces polymères. La toxicité aiguë du DeBDE est
    très faible et son absorption au niveau des voies digestives est
    minime. On peut donc considérer comme insignifiant le risque que le
    DeBDE représente pour la population générale.

        C'est sous forme particulaire que le DeBDE peut donner lieu à une
    exposition professionnelle. En se prémunissant contre les poussières
    au cours de la fabrication et de l'utilisation de ce produit, on peut
    efficacement en réduire les risques pour les travailleurs.

        Le DeBDE est persistant et il se fixe sur les particules de
    matière présentes dans l'environnement; il est vraisemblable qu'il
    s'accumule dans les sédiments. En revanche, sa bioaccumulation est
    improbable. D'après les données disponibles, la photodécomposition du
    DeBDE en milieu aqueux dans l'environnement ne conduit pas à la
    formation de diphényléthers bromés inférieurs ni de
    bromodibenzofuranes, mais on est mal renseigné sur la décomposition de
    ce composé dans d'autres milieux.

        On est également très peu renseigné sur la toxicité du DeBDE pour
    les êtres vivants dans leur milieu naturel.

    2.2  Produits de décomposition

        Il peut se former des PBDF et, dans une certaine mesure, des PBDD
    lorsque du DeBDE ou des produits qui en contiennent sont chauffés à
    300-800°C. Il faut se préoccuper des dangers que ces produits
    pourraient représenter,.

        Lorsqu'elle est correctement conduite, l'incinération n'entraîne
    pas l'émission de quantités importantes de bromodioxines ou de
    bromodibenzofuranes. Si la combustion s'effectue dans des conditions
    non contrôlées, des PBDF et des PBDD peuvent prendre naissance en
    quantités indéterminées. Les risques qui pourraient en résulter pour
    l'homme et l'environnement seront étudiés dans un prochain Critère
    d'hygiène de l'environnement sur les PBDF et les PBDD.

        On a observé la présence de PBDF dans le sang de travailleurs
    employés à la production de matières plastiques contenant du DeBDE.
    Toutefois aucun effet délétère sur leur santé n'a pu être attribué à
    ce type d'exposition. Moyennant des techniques appropriées, il est
    possible d'éviter l'exposition des travailleurs aux PBDF.

    3  Recommandations

    3.1  Recommandations générales

    *   Il convient que les travailleurs qui sont employés à la
        fabrication de DeBDE et de produits qui en contiennent soient
        protégés contre toute exposition par l'application de mesures
        appropriées d'hygiène industrielle, la surveillance de
        l'exposition professionnelle et des moyens techniques appropriés.

    *   Il convient de minimiser l'exposition environnementale par un
        traitement approprié des effluents et des émissions produits par
        les industries qui utilisent ce composé ou des produits qui en
        contiennent. Le rejet des déchets industriels et des produits de
        consommation doit être réglementé afin de réduire au minimum la
        contamination de l'environnement par ce composé persistant et ses
        produits de décomposition.

    *   Les fabricants doivent faire en sorte que le DeBDE commercial
        contienne le minimum d'impuretés, en utilisant pour cela les
        meilleures techniques existantes. Une pureté d'au moins 97% est
        recommandée.

    *   On ne doit procéder à l'incinération qu'au moyen d'incinérateurs
        convenables, qui fonctionnent toujours dans les conditions
        optimales. Le brûlage des déchets par tout autre moyen risque
        d'entraîner la formation de PBDF et/ou de PBDD.

    3.2  Etudes à effectuer

    *   Il conviendrait d'effectuer, sur les organismes appropriés, des
        études sur la biodisponibilité et la toxicité du DeBDE lié aux
        sédiments.

    *   Il importe d'assurer une surveillance permanente des
        concentrations dans l'environnement.

    *   La production de PBDF en situation réelle d'incendie doit faire
        l'objet d'études plus approfondies.

    *   Il importe d'étudier plus à fond la biodécomposition dans
        l'environnement ainsi que la photodécomposition de ce composé dans
        des milieux autres que l'eau.

    *   Il conviendrait d'étudier des méthodes pour le recyclage des
        polymères contenant du DeBDE et leurs conséquences.

    *   Il faudrait valider les méthodes d'analyse du DeBDE dans diverses
        matrices.

    NONABROMODIPHENYLETHER

        Le nonabromodiphényléther n'est ni produit ni utilisé. On ne
    dispose d'aucune donnée sur les points suivants:

    *   Transport, distribution et transformation dans l 'environnement

    *   Concentrations dans l'environnement et exposition humaine

    *   Cinétique et métabolisme chez les animaux de laboratoire et
        l'homme

    *   Effets sur les mammifères de laboratoire et les systèmes d'épreuve
         in vitro

    *   Effets sur l'homme

    *   Effets sur les autres êtres vivants au laboratoire et dans leur
        milieu naturel

    *   Evaluations antérieures par des organismes internationaux.

    1  Résumé et évaluation

        Il n'existe aucune base de données sur laquelle se fonder pour une
    évaluation.

    2  Recommandations

        Il importe de réduire au minimum le taux de contamination des
    retardateurs de flamme bromés du commerce par le
    nonabromodiphényléther afin d'éviter une pollution de l'environnement
    et l'exposition humaine.

    OCTABROMODIPHENYLETHER

        L'octabromodiphényléther n'est ni fabriqué ni utilisé à l'état
    pur. On ne dispose d'aucune donnée sur les points suivants:

    *   Cinétique et métabolisme chez les animaux de laboratoire et
        l'homme

    *   Effets sur l'homme

    *   Effets sur les autres êtres vivants au laboratoire et dans leur
        milieu naturel

    *   Evaluations antérieures par des organismes internationaux.

    1.  Résumé et évaluation

    1.1  Identité et propriétés physiques et chimiques

        L'OBDE du commerce se présente sous la forme d'un mélange
    d'environ 11% de PeBDE/HxBDE, 44% de HpBDE, 31-35% d'OBDE, 10% de NBDE
    et 0,5% de DeBDE. D'après la structure chimique, il y a thé-oriquement
    12 isomères de l'OBDE et 24 isomères de l'HpBDE.

        Le point de fusion varie d'environ 80°C à >200°C. La tension de
    vapeur est <10-7 mmHg, la solubilité dans l'eau est faible et le
    logarithme du coefficient de partage  n-octanol/eau est >5,5. Ces
    variations dans les propriétés physiques s'expliquent par des
    différences de composition des mélanges étudiés.

    1.2  Production et usages

        La consommation mondiale annuelle d'OBDE commercial est de 6000
    tonnes, dont 70% sont utilisés comme retardateurs de flamme dans les
    résines ABS qui servent à la fabrication d'ordinateurs et d'armoires
    de bureau. L'OBDE vient au second rang des retardateurs de flamme dans
    l'ordre d'utilisation.

    1.3  Transport, distribution et transformation dans l'environnement

        On a trouvé des constituants de l'OBDE du commerce dans des
    sédiments aquatiques et des tissus adipeux humains. Certains de ces
    constituants à plus faible teneur en brome (HxBDE et PeBDE) ont été
    observés dans des biotes. On n'a pas décelé d'OBDE, mais on n'a
    cherché généralement ni le HpBDE ni le NBDE. Les constituants de
    l'OBDE commercial sont vraisemblablement persistants mais, lorsque le
    degré de substitution par le brome dépasse 6, la bioaccumulation
    devient de plus en plus improbable. On a trouvé chez la carpe un
    facteur de bioaccumulation de moins de 2 pour un OBDE commercial.

        La pyrolyse de l'OBDE commercial, soit tel quel, soit ajouté à des
    polymères comme retardateur de flamme (avec ou sans Sb2O3) à 600°C,
    produit des PBDF et, à beaucoup plus faibles concentrations, des PBDD.
    Le traitement des résines ABS avec de l'OBDE et du Sb2O3 dans
    différentes conditions révèle, que dans les conditions normales, il ne
    se forme que de faibles concentrations de PBDF. Lorsque les conditions
    sont mauvaises, les concentrations sont beaucoup plus élevées. En
    revanche, les concentrations de PBDD sont faibles dans les deux cas.

    1.4  Concentrations dans l'environnement et exposition humaine

        Dans des échantillons d'eau recueillis au Japon en 1987 et 1988,
    on n'a pas pu déceler d'OBDE ni de constituants de l'OBDE du commerce
    à plus faible teneur en brome. On a également analysé des échantillons
    de sédiments et dans environ 2-6% d'entre eux, on a observé la
    présence d'OBDE à des concentrations de 8-22 µg/kg de poids sec. Dans
    le sédiment, on a également trouvé des constituants moins substitués
    en brome.

        Chez des poissons capturés au Japon en 1987 et en 1988, on n'a pas
    décelé d'OBDE.

        Aux Etats-Unis d'Amérique, on a analysé en 1987 des échantillons
    de tissus adipeux humains à la recherche de PBDF et de PBDD. Les
    échantillons provenaient de 865 prélèvements associés de manière à
    former 48 homologues composites. Ce schéma d'échantillonnage composite
    reposait sur 9 divisions censitaires et 3 groupes d'âge. Dans ces
    échantillons, on a également constaté la présence de PBDE et les
    premiers résultats ont montré que de l'OBDE était également présent
    dans 60% des cas avec une concentration estimative allant jusqu'à
    8000 ng/kg.

    1.5  Cinétique et métabolisme chez les animaux de laboratoire et
         l'homme

        Aucune donnée disponible.

    1.6  Effets sur les mammifères de laboratoire et les systèmes d'épreuve
         in vitro

        L'OBDE du commerce présente une faible toxicité aiguë pour les
    mammifères de laboratoire. Il n'est pas irritant pour la peau et ne
    provoque qu'une légère irritation oculaire chez le lapin. Lors
    d'études toxicologiques à court terme (respectivement 4 et 13
    semaines), on a observé, chez des rats à qui l'on en avait administré
    dans leur nourriture à raison de 100 mg/kg, une augmentation du poids
    du foie et des altérations microscopiques caractérisées par la
    présence, dans la région centro- et médio-lobulaire, de cellules
    parenchymateuses hypertrophiées contenant des structures granulaires.

    La gravité de ces lésions hépatiques était plus marquée aux doses
    élevées, c'est-à-dire 1000 et 10 000 mg/kg de nourriture. En outre, on
    a observé une hyperplasie de la thyroïde. La teneur en brome total de
    ces tissus a augmenté au cours de l'étude pour diminuer ensuite
    lentement au cours de la période de récupération. Les anomalies
    hépatiques étaient réversibles. Lors d'une étude toxicologique par
    inhalation au cours de laquelle on a fait respirer de la poussière
    micronisée d'OBDE aux animaux (8 h/jour, 14 jours de suite) on n'a pas
    observé d'effets à la concentration de 1,2 mg/m3 mais à celle de
    12 mg/m3, on a observé des lésions hépatiques analogues à celles qui
    avaient été décelées après ingestion du produit.

        Chez le rat, des doses relativement faibles d'OBDE du commerce
    accroissent d'activité du cytochrome P-450 et induisent les enzymes
    des microsomes hépatiques, comme l'UDP-glucuronyl-transférase et la
    benz[a]pyrène-hydroxylase. On a également constaté que ce produit
    avait un effet porphyrinogène sur les cultures de cellules hépatiques
    d'embryon de poulet.

        L'étude du pouvoir tératogène de l'OBDE chez le rat a montré qu'à
    fortes doses (25,0 et 50,0 mg/kg de poids corporel), ce produit
    provoquait des résorptions ou un retard d'ossification en différents
    points du squelette ainsi que des malformations foetales. Les
    malformations observées aux doses de 25 mg/kg de poids corporel et
    au-delà étaient très vraisemblablement liées à la toxicité du produit
    pour la mère. Ces malformations n'ont pas été observées aux doses
    inférieures ou égaies à 15,0 mg/kg de poids corporel. Chez le lapin,
    aucun signe d'activité tératogène n'a été observé, en revanche on a
    constaté une certaine foetotoxicité à la dose de 15 mg/kg de poids
    corporel qui était également toxique pour la mère. D'après les études
    de tératogénicité, la dose sans effets nocifs observables est de
    2,5 mg/kg de poids corporel.

        Lors de deux études, l'une de 28 jours et l'autre de 90 jours, on
    a constaté qu'une dose de 100 mg d'OBDE/kg de nourriture (soit
    l'équivalent de 5 mg/kg de poids corporel) ne produisait que des
    effets minimes sur le foie. On n'a pas cherché à établir la dose sans
    effets observables.

        Toutes les épreuves de mutagénicité: synthèse non programmée de
    l'ADN, tests sur microorganismes  in vitro et recherche d'échanges
    entre chromatides-soeurs sur cellules ovariennes de hamster chinois se
    sont révélées négatives.

        On ne possède aucune donnée résultant d'études de cancéro-génicité
    ou d'études à long terme.

    1.7  Effets sur l'homme

        Aucune donnée disponible.

    1.8  Effets sur les autres êtres vivants au laboratoire et dans leur
         milieu naturel

        Données minimales.

    2  Conclusions

    2.1  OBDE

        L'OBDE du commerce est un mélange d'hexa-, d'hepta-, d'octa- et de
    nonabromodiphényléthers, qui sont tous des composés rémanents, en
    grande partie fixée aux sédiments.

        L'OBDE est très largement utilisé comme retardateur de flamme dans
    les polymères. Il peut y avoir contact avec la population générale par
    l'intermédiaire de produits fabriqués à partir de ces polymères. Il
    est peu probable qu'on puisse être exposé à de l'OBDE qui aurait été
    extrait de ces polymères.

        L'OBDE présente une faible toxicité aiguë. On ne dispose d'aucune
    donnée sur sa fixation ou son élimination par l'organisme des
    mammifères. Il n'est ni tératogène ni mutagène. On ne dispose d'aucune
    donnée sur sa toxicité à long terme ni sur sa cancéro-génicité.

        On a relevé la présence, dans des tissus adipeux humains, de
    plusieurs constituants de l'OBDE commercial. Pour la population dans
    son ensemble, le risque d'intoxication aiguë est vraisemblablement
    faible. Il n'est pas possible d'évaluer les risques d'une exposition à
    long terme en raison de l'absence d'études toxicologiques pertinentes.

        On ne dispose non plus d'aucune information qui permette de tirer
    des conclusions quant à l'exposition professionnelle à l'OBDE et à ses
    effets.

        Les données relatives à la toxicité de l'OBDE pour les êtres
    vivants dans leur milieu naturel demeurent limitées. Il est possible
    que les constituants peu substitués en brome du mélange commercial
    subissent une bioaccumulation.

    2.2  Produits de décomposition

        Lors du chauffage de l'OBDE ou de produits qui en contiennent à
    des températures de 400-800°C, il peut se former des PBDF et, dans une
    certaine mesure, des PBDD. Il importe de se préoccuper des dangers qui
    pourraient en résulter.

        Il est improbable que la population générale soit exposée de façon
    notable aux impuretés de type PBDF, présentes dans les polymères
    contenant des retardateurs de flamme. Moyennant une incinération dans
    les règles, il ne devrait pas y avoir d'émission importante de
    bromodioxines ni de bromofuranes. Le brûlage sans précautions de
    produits qui contiennent de l'OBDE du commerce, peut donner naissance
    à des PBDF et des PBDD en quantités indéterminées. Ce problème et ses
    conséquences pour la santé humaine et l'environnement, seront abordés
    dans un prochain Critère d'hygiène de l'environnement consacré aux
    PBDF et aux PBDD.

    3  Recommandations

    3.1  Recommandations générales

    *   Il convient d'utiliser les meilleurs techniques possibles pour la
        fabrication de l'OBDE du commerce, afin de réduire au minimum la
        teneur en homologues hexabromés ou moins substitués, du fait de
        leur possibilité de bioaccumulation dans l'environnement.

    *   Les travailleurs qui sont employés à la fabrication de l'OBDE ou
        de produits qui en contiennent, doivent être protégés contre
        l'exposition à ces dérivés par des mesures d'hygiène industrielle,
        une surveillance de l'exposition professionnelle et des moyens
        techniques.

    *   Il convient de limiter au maximum la pollution de l'environnement
        grâce à un traitement approprié des effluents et des émissions
        provenant d'industries qui utilisent le composé ou des produits
        qui en contiennent. Le rejet de produits industriels et de
        produits de consommation devra être réglementé de façon à réduire
        au minimum la pollution de l'environnement par ces composés
        rémanents et leurs produits de décomposition.

    *   L'incinération de produits qui contiennent des retardateurs de
        flamme à base d'OBDE, ne doit s'effectuer que dans des
        incinérateurs appropriés fonctionnant toujours dans des conditions
        optimales. Le brûlage par tout autre moyen risque de donner
        naissance à des PBDF ou des PBDD.

    3.2  Etudes à effectuer

        Comme la base de données toxicologiques actuelle est insuffisante
    pour permettre d'évaluer les dangers que représente l'OBDE du commerce
    pour l'homme et l'environnement, et pour en faciliter l'utilisation,
    il est recommandé d'entreprendre les études suivantes:

    *   Etudes, sur des organismes appropriés, relatives à la
        biodisponibilité et à l'écotoxicité des constituants de l'OBDE du
        commerce liés aux sédiments

    *   Surveillance généralisée de la concentration des constituants de
        l'OBDE du commerce dans l'environnement

    *   Etudes toxicologiques à long terme et études de cancéro-génicité
        portant sur l'OBDE du commerce

    *   Surveillance de l'exposition professionnelle à l'OBDE du commerce

    *   Poursuite des études sur la formation de PBDF dans des conditions
        réelles d'incendie

    *   Poursuite des études sur la biodécomposition et la
        photodécomposition environnementales dans des milieux non aqueux

    *   Etudes de méthodes de recyclage des polymères contenant de l'OBDE
        et de ses conséquences

    *   Validation des méthodes d'analyse de l'OBDE dans diverses matrices

    *   Etudes sur la possibilité de migration à partir de divers types de
        polymères.

    HEPTABROMODIPHENYLETHER

        L'heptabromodiphényléther n'est ni produit ni utilisé.

        Il n'existe pas de base de données relatives à l'HpBDE pur sur
    laquelle fonder une évaluation.

        On ne dispose d'aucune donnée sur les points suivants:

    *   Cinétique et métabolisme chez les animaux de laboratoire et
        l'homme

    *   Effets sur l'homme

    *   Effets sur les autres êtres vivants au laboratoire et dans leur
        milieu naturel

    *   Evaluations antérieures par des organismes internationaux.

        Du fait que l'HpBDE est le principal constituant de
    l'octabromodiphényléther du commerce, le résumé, l'évaluation, les
    conclusions et les recommandations relatives à l'OBDE du commerce,
    valent pour l'HpBDE "du commerce".

    HEXABROMODIPHENYLETHER

        L'hexabromodiphényléther n'est ni produit ni utilisé mais il
    constitue une impureté des bromodiphényléthers du commerce. Il
    convient d'en réduire la concentration au minimum afin d'éviter la
    contamination de l'environnement et l'exposition de l'homme.

        Il n'existe pas de base de données sur laquelle fonder une
    évaluation.

        On ne dispose d'aucune donnée sur les points suivants:

    *   Effets sur les mammifères de laboratoire et les systèmes d'épreuve
         in vitro

    *   Effets sur l'homme

    *   Effets sur les autres êtres vivants au laboratoire et dans leur
        milieu naturel

    *   Evaluations antérieures par des organismes internationaux.

    PENTABROMODIPHENYLETHER

        Le pentabromodiphényléther n'est ni produit ni utilisé.

        On ne dispose d'aucune donnée sur les points suivants:

    *   Effets sur l'homme

    *   Effets sur les autres êtres vivants au laboratoire et dans leur
        milieu naturel

    *   Evaluations antérieures par des organismes internationaux.

    1  Résumé et évaluation

    1.1.1  Identité, propriétés physiques et chimiques

        Le pentabromodiphényléther du commerce (PeBDE) est un mélange de
    tétra-, penta- et hexabromodiphényléther. Il contient
    approximativement 50-60% de PeBDE et 24-38% de TeBDE. D'après la
    structure chimique, il existe théoriquement 46 isomères du PeBDE et 42
    isomères du TeBDE. Les principaux constituants des produits du
    commerce semblent être au nombre de 3, à savoir le 2,2',4,4',5'-PeBDE,
    le 2,2',4,4'-TeBDE et un analogue non identifié à 5 atomes de brome.

        Le point de fusion se situe entre -7 et -3°C et le point
    d'ébullition au-delà de 200°C. La tension de vapeur est faible:
    <10-7 mmHg et la solubilité dans l'eau, négligeable. Le logarithme
    du coefficient de partage  n-octanol/eau est >6.

    1.2  Production et usage

        Le PeBDE est utilisé comme additif dans les résines époxy, les
    résines phénoliques, les polyesters et le polyuréthanne ainsi que les
    textiles. La consommation mondiale est d'environ 4000 tonnes par an.
    C'est l'un des principaux bromodiphényléthers du commerce utilisés
    comme retardateurs de flamme.

    1.3  Transport, distribution et transformation dans l'environnement

        On trouve des constituants du PeBDE du commerce dans les biotes,
    les sédiments et les boues d'égouts. Il est vraisemblable que ces
    constituants soient rémanents et qu'ils aient tendance à la
    bioaccumulation. C'est ainsi que l'on a trouvé chez la carpe un
    facteur de bioconcentration de plus de 10 000.

        L'étude de la pyrolyse du PeBDE du commerce a montré qu'il se
    forme au cours de ce processus des PBDF et des PBDD. La température
    optimale de formation de ces composés se situe entre 700 et 800°C.
    Lorsque la pyrolyse du PeBDE s'effectue en l'absence d'oxygène, il y a
    formation de polybromobenzènes, de polybromophénols et de PBDF.

    1.4  Concentrations dans l'environnement et exposition humaine

        Dans des échantillons de sédiments prélevés au Japon dans des
    cours d'eau et des estuaires, on a relevé des concentrations allant de
    0 (<2 µg/kg)jusqu'à 28 µg/kg de poids sec de PeBDE. En Suède, les
    sédiments de certains cours d'eau accusaient des concentrations allant
    jusqu'à 1200 µg de 2,2',4,4',5'-PeBDE/kg. Des boues d'égouts,
    analysées en Suède, contenaient également de ce PeBDE.

        Des moules et poissons ont été prélevés aux fins d'analyse dans
    diverses zones littorales du Japon entre 1981 et 1985; dans deux
    échantillons de moules sur cinq, on a trouvé des concentrations de
    PeBDE qui étaient respectivement égaies à 0,4 et 2,8 µg/kg de poids
    humide. En revanche, dans le poisson, on n'a pas décelé de PeBDE
    (limite de dosage <0,2 µg/kg). On a fait état de concentrations de
    1,9-22 µg/kg de poids frais dans des échantillons de foie de morue
    provenant de la mer du Nord. En Suède, on a trouvé des concentrations
    qui se situaient entre 7,2 et 64 µg de 2,2',4,4',5'-PeBDE/kg de
    graisse dans des poissons d'eau douce du genre corégone et dans des
    harengs de différentes provenances.

        Du gras de phoque ( Phoca hispida et phoque gris) prélevé en
    Suède en 1979-85, s'est révélé contenir des concentrations moyennes de
    2,2',4,4',5'-PeBDE respectivement égaies à 1,7 µg et 40 µg/kg de poids
    corporel.

        En Suède, dans un mélange d'échantillons de muscles de lapins et
    d'élans ainsi que dans de la graisse de rognon de renne, on a
    constaté, en 1985-86, la présence de concentrations respectivement
    égaies à <0,3 µg, 0,64 µg et 0,26 µg de 2,2',4,4',5'-PeBDE/kg de
    graisse.

        Dans des échantillons de muscles de balbuzard, obtenus en Suède en
    1982-86, on a noté une concentration moyenne de 140 µg de
    2,2,',4,4',5'-PeBDE/kg de graisse.

        On a constaté qu'au cours des dernières décennies, la
    concentration de deux isomères du PeBDE avait augmenté d'un facteur 10
    dans les oeufs de guillemots de la Baltique. On a également constaté
    que la concentration de ces isomères avait augmenté d'un facteur 4
    dans des brochets provenant d'un lac du sud de la Suède. L'analyse de
    sédiments de la Baltique représentatifs de plusieurs années
    d'échantillonnage indique également qu'il y a eu une augmentation
    considérable de la pollution au cours de la dernière décennie.

        On est très peu renseigné sur l'exposition humaine mais on peut
    estimer en gros, d'après la consommation de poisson des suédois, que
    la population de ce pays absorbe individuellement environ 0, 1 µg de
    PeBDE par jour.

    1.5  Cinétique et métabolisme chez les animaux de laboratoire et
         l'homme

        La demi-vie du PeBDE n'a été étudiée qu'au niveau de la graisse
    périrénale chez le rat. On a ainsi obtenu une valeur comprise entre 25
    et 47 jours, en fonction du sexe de l'animal et du type d'isomère en
    cause.

    1.6  Effets sur les mammifères de laboratoire et les systèmes d'épreuve
         in vitro

        Le PeBDE du commerce présente une faible toxicité aiguë par voie
    orale chez le rat; la toxicité par voie percutanée est également
    faible chez le lapin. En exposant pendant une brève durée des rats par
    la voie respiratoire et en instillant du PeBDE à des lapins dans le
    sac conjonctival, on n'a obtenu que des effets modérés et passagers.

        Des études toxicologiques à court terme sur des rats (4 semaines
    et 13 semaines respectivement) au cours desquelles du PeBDE a été
    administré aux animaux à des concentrations de 100 mg/kg de
    nourriture, ont révélé une augmentation du poids du foie et donné lieu
    à de légères anomalies histologiques. Ces anomalies consistaient en
    une hypertrophie des cellules du parenchyme hépatique, qui avaient un
    aspect granulaire et contenaient des "inclusions rondes" éosinophiles.
    On a constaté que la teneur en brome total du foie augmentait en
    fonction de la dose administrée et restait élevée pendant des périodes
    pouvant aller jusqu'à 24 semaines. On a également observé une légère
    hyperplasie thyroïdienne réversible.

        Après administration par voie orale de doses quotidiennes de PeBDE
    ne dépassant pas 0,78 µmol/kg de poids corporel, on a observé
    l'induction des enzymes hépatiques et un accroissement de l'activité
    du cytochrome P-450 c. Les résultats des épreuves de tératogénicité et
    de mutagénicité se sont révélés négatifs.

        Aucune étude toxicologique à long terme ou étude de
    cancérogénicité n'a été publiée.

    1.7  Effets sur l'homme

        Pas de données disponibles.

    1.8  Effets sur les autres êtres vivants au laboratoire et dans leur
         milieu naturel

    On ne dispose que d'un minimum de données.

    2  Conclusions

    2.1  PeBDE

        Le PeBDE du commerce (mélange de 24-38% de tétra-, 50-60% de
    penta- et 4-8% d'hexabromodiphényléther) est rémanent et il s'accumule
    chez les êtres vivants dans leur milieu naturel.

        Le PeBDE du commerce est largement utilisé, incorporé à des
    polymères, comme retardateur de flamme. Lorsqu'il entre en contact
    avec la population, c'est par l'intermédiaire de produits fabriqués à
    partir de ces polymères. Il est improbable qu'il puisse y avoir
    exposition après extraction du produit de ces polymères. Il peut y
    avoir exposition de l'homme au PeBDE par l'intermédiaire de la chaîne
    alimentaire, étant donné que la substance a été décelée chez divers
    animaux vivant dans leur milieu naturel, animaux qui servent de
    nourriture à l'homme, comme les poissons, les fruits de mer, etc. On
    constate depuis au moins deux décennies que les concentrations
    augmentent chez les poissons et les oiseaux de Suède.

        Le PeBDE du commerce présente une faible toxicité aiguë. On ne
    possède aucune donnée sur la fixation et l'élimination de ce produit
    chez les mammifères. On ne dispose pas non plus d'études sur la
    reproduction d'animaux exposés à cette substance, ni sur sa toxicité à
    long terme ou sa cancérogénicité.

        Il n'est pas possible, à partir des données disponibles, d'évaluer
    le risque qu'il représente pour la population générale.

        On ne possède pas non plus de données qui permettent d'établir le
    niveau d'exposition professionnelle ou de se prononcer sur les effets
    du PeBDE ?? du commerce.

        On ne dispose que de données limitées sur la toxicité du PeBDE du
    commerce pour les êtres vivants dans leur milieu naturel.

    2.2  Produits de décomposition

        Lorsqu'on chauffe du PeBDE ou des produits qui en contiennent à
    une température de 400-800°C, il se forme des PBDF et, dans une
    certaine mesure, des PBDD. Il faudra examiner les risques qui
    pourraient en découler.

        Il est peu probable que la population générale soit exposée de
    façon notable aux PBDF produits par des polymères contenant du PeBDE
    comme retardateur de flamme. Si elle est convenablement effectuée,
    l'incinération n'entraîne pas l'émission de quantités importantes de
    bromodioxines ou de bromofuranes. En revanche, le brûlage inconsidéré
    de produits qui en contiennent peut donner naissance à des quantités
    indéterminées de PBDF ou de PBDD. Dans un futur Critère d'hygiène de
    l'environnement consacré à ces deux substances, l'importance de ce
    problème pour l'homme et l'environnement sera examinée.

    3  Recommandations

    3.1  Recommandations générales

        La rémanence du PeBDE du commerce dans l'environnement et son
    accumulation dans les êtres vivants militent contre l'utilisation de
    ce produit. Toutefois, s'il l'on continue à l'utiliser, il faudra
    prendre les précautions suivantes:

    *   Les travailleurs qui sont employés à la production de PeBDE ou de
        polymères qui en contiennent, doivent être protégés contre toute
        exposition, par des mesures appropriées d'hygiène industrielle, la
        surveillance de l'exposition professionnelle et des moyens
        techniques convenables.

    *   Il convient de minimiser l'exposition environnementale par un
        traitement approprié des effluents et des émissions produits par
        les industries qui utilisent ce composé ou des produits qui en
        contiennent. Le rejet des déchets industriels et des produits de
        consommation doit être réglementé afin de réduire au minimum la
        contamination de l'environnement par ce composé qui persiste et
        s'accumule et par ses produits de décomposition.

    *   On ne doit procéder à l'incinération qu'au moyen d'incinérateurs
        convenables fonctionnant toujours dans des conditions optimales.
        Le brûlage des déchets par tout autre moyen risque d'entraîner la
        formation de produits de décomposition toxiques.

    3.2  Etudes à effectuer

    *   Il faut poursuivre la surveillance des concentrations dans
        l'environnement.

    *   Il conviendrait de valider les méthodes de dosage du PeBDE dans
        diverses matrices.

    *   Du fait que la base de données toxicologiques actuelle est
        insuffisante pour permettre d'évaluer des risques pour l'homme et
        l'environnement du PeBDE du commerce et en justifier
        l'utilisation, il conviendrait d'entreprendre les éludes
        suivantes:

        -   études complémentaires de cancérogénicité et études
            toxicologiques et écotoxicologiques:

        -   poursuite des travaux sur la formation de PBDF dans les
            conditions réelles d'incendie;

        -   étude de méthodes pour le recyclage des polymères contenant du
            PeBDE et de leurs conséquences;

        -   études sur les possibilités de migration à partir de produits
            contenant des retardateurs de flamme.

    TETRABROMODIPHENYLETHER

        Le tétrabromodiphényléther n'est ni produit ni utilisé.

        Il n'existe aucune donnée sur les points suivants:

    *   Effets sur les mammifères de laboratoire et les systèmes d'épreuve
         in vitro

    *   Effets sur l'homme

    *   Effets sur les autres êtres vivants au laboratoire et dans leur
        milieu naturel

    *   Evaluations antérieures par des organismes internationaux.

    1  Résumé et évaluation

    1.1  Identité, propriétés physiques et chimiques

        Le tétrabromodiphényléther du commerce est constitué d'un mélange
    de 41% de tétra-, 45% de penta-, et 7% d'hexabromo-diphényléthers plus
    environ 7% d'un PBDE de structure inconnue. D'après la structure
    chimique, le tétrabromodiphényléther a théoriquement 42 isomères. On
    ne dispose pratiquement d'aucune donnée sur les propriétés physiques
    et chimiques de ce composé, à part le logarithme du coefficient de
    partage  n-octanol/eau, qui est 5,87-6,16.

    1.2  Production et usages

        D'après un rapport, la production (et l'usage) du TeBDE aurait été
    d'environ 1000 tonnes en 1987 au Japon. Autant qu'on sache, il
    n'existe actuellement aucune production sous le nom de
    tétra-bromodiphényléther, mais le composé est présent dans la
    proportion de 24 à 38% dans le pentabromodiphényléther du commerce.

    1.3  Transport, distribution et transformation dans l'environnement

        On a trouvé des constituants du TeBDE du commerce dans des biotes,
    des sédiments et des boues d'égouts. Il est probable que les
    constituants du TeBDE du commerce (qui contiennent des quantités à peu
    près équivalentes de PeBDE) aient un caractère rémanent et subissent
    une bioaccumulation.

        L'étude de la pyrolyse du TeBDE du commerce montre qu'à 800°C, il
    se forme des PBDF et des PBDD, mais uniquement les homologues
    inférieurs.

    1.4  Concentrations dans l'environnement et exposition humaine

        Au Japon, on a trouvé du TeBDE dans les sédiments de cours d'eau à
    des concentrations de 12-31 µg/kg de poids sec et en Suède, à des
    concentrations allant jusqu'à 840 µg/kg (perte au feu). La présence de
    TeBDE a été également constatée en Suède dans des boues d'égouts à la
    concentration de 15 µg/kg.

        Au Japon, on a constaté, dans des moules et des poissons de
    différentes provenances, la présence de TeBDE à des concentrations
    allant de <0, 1 à 14,6 µg de 2,2',4,4'-TeBDE/kg de poids humide. En
    Suède, on a capturé dans des cours d'eau diverses espèces de poissons
    que l'on a analysés à la recherche de 2,2',4,4'-TeBDE. Les
    concentrations moyennes allaient de 0 (<0,1 mg/kg) à 100 mg/kg de
    graisse. L'analyse a montré qu'il existait au moins une source de
    pollution locale dans un certain cours d'eau. Des corégones, des
    ombles arctiques et des harengs pêchés en différents lieux de Suède
    entre 1986 et 1987 se sont révélés contenir des concentrations de
    TeBDE respectivement égaies à 15, 400 et 59-450 µg de
    2,2',4,4'-TeBDE/kg de graisse. En Allemagne, des poissons provenant de
    différents cours d'eau en contenaient jusqu'à 1 mg/kg de graisse.

        Dans les harengs et les foies de morues pêchés dans la partie
    méridionale, centrale et septentrionale de la mer du Nord, au cours de
    la période 1983-89, on a noté une tendance à la diminution des
    concentrations de TeBDE de la région méridionale à la région
    septentrionale. Dans les harengs, la concentration allait de 8,4 à
    100 µg de 2,2',4,4'-TeBDE/kg de graisse.

        Dans le tissu musculaire d'oiseaux nichant et hivernant en mer
    Baltique, en mer du Nord et au Spitzberg, on a relevé des
    concentrations de 2,2',4,4'-TeBDE de 80-370 µg/kg de graisse. Chez des
    balbuzards capturés en Suède au cours de la période 1982-86, on a
    mesuré des concentrations moyennes de 1800 µg/kg de graisse.

        En Suède, on constate une tendance à l'augmentation des
    concentrations de 2,2',4,4'-TeBDE dans les sédiments de la Baltique,
    les poissons d'eau douce et les oeufs d'oiseaux de mer.

        Dans la graisse de phoques de la mer Baltique et du Spitzberg on a
    observé des concentrations de 10-730 µg/kg de graisse.
    Chromatographiquement, le PBDE est analogue au Bromkal 70-5. Sur des
    échantillons groupés de graisse de phoques de l'espèce  Phoca hispida
    et de phoques gris, prélevés en Suède au cours de la période 1979-85,
    on a mesuré des concentrations respectivement égaies à 47 µg et 650 µg
    de 2,2',4,4'-TeBDE/kg.

        Dans des échantillons groupés de muscles de mammifères terrestres,
    par exemple des lapins, des élans et des rennes, obtenus en 1985-86 en
    Suède, on a observé des concentrations moyennes respectivement égaies
    à <2, 0,82, et 0,18 µg de 2,2',4,4'-TeBDE/kg de graisse.

        En Allemagne, on a trouvé dans quatre échantillons de lait de
    vache, des concentrations de 2,5-4,5 µg de PBDE/kg de matière grasse,
    sous la forme de Bromkal 70DE. Dans le même pays et sous cette même
    forme, on a retrouvé du PBDE dans le lait de 25 femmes à des
    concentrations de 6,2-11,1 µg/kg de matière grasse.

        Une estimation approximative de l'exposition de la population
    suédoise, calculée en fonction de la consommation de poisson en Suède,
    donne une absorption individuelle de 0,3/µg de TeBDE/jour.

    1.5  Effets sur les mammifères de laboratoire et les systèmes d'épreuve
         in vitro

        Il n'existe pas de données sur le TeBDE lui-même, cependant on
    dispose de données de toxicité aiguë et de toxicité à court terme pour
    le PeBDE du commerce qui contient 41% de TeBDE.

    1.6  Cinétique et métabolisme chez les animaux de laboratoire et
         l'homme

        On ne possède qu'un minimum de données.

    1.7  Effets sur l'homme

        Il n'existe aucune donnée.

    1.8  Effets sur les autres vivants au laboratoire et dans leur milieu
         naturel

        Il n'existe aucune donnée.

    2  Conclusions

    2.1  TeBDE

        Les constituants du TeBDE du commerce (mélange à 41% de
    2,2',4,4'-tétra-; 45% de 2,2',4,4',5'-penta; 7% d'hexa-, et 7-8% de
    polybromodiphényléther de structure inconnue) persistent dans
    l'environnement et s'accumulent chez les êtres vivants dans leur
    milieu naturel.

        Constituant du pentabromodiphényléther, le TeBDE est très souvent
    incorporé à des polymères comme retardateur de flamme. La population
    générale peut entrer en contact avec cette substance par
    l'intermédiaire de produits fabriqués à partir de ces polymères. Il
    est improbable qu'il puisse y avoir exposition par suite de
    l'extraction du composé de ces polymères. Il peut y avoir exposition
    humaine a TeBDE par l'intermédiaire de la chaîne alimentaire car on a
    décelé la présence de ce composé chez des animaux dans leur milieu
    naturel, animaux qui servent de nourriture à l'homme comme les
    poissons, les fruits de mer, etc. En Suède, on observe depuis les deux
    dernières décennies une augmentation des concentrations de ce composé
    chez les poissons et les oiseaux.

        On manque d'information au sujet des études toxicologiques à court
    et à long terme, des éludes de cancérogénicité ou sur la reproduction
    qui auraient pu être faites. En outre, on ne dispose pas de données
    sur la cinétique et le métabolisme du produit chez les animaux de
    laboratoire et l'homme.

        Il n'est pas possible d'évaluer le risque pour la population
    générale sur la base des données disponibles.

        On ne dispose pas non plus de données suffisantes pour déterminer
    les niveaux d'exposition professionnelle ni pour se prononcer sur les
    effets du TeBDE.

        Il n'existe aucune donnée sur la toxicité de TeBDE du commerce
    pour les êtres vivants dans leur milieu naturel.

    2.2  Produits de décomposition

        Lorsqu'on chauffe du TeBDE à 800°C, il se forme des PBDF et des
    PBDD. Il faudra étudier les dangers que cela peut comporter.

        Il n'est guère probable que la population générale soit exposée de
    façon importante aux PBDF qui se forment lorsque l'on chauffe des
    polymères contenant du TeBDE comme retardateur de flamme. Si
    l'incinération est effectuée correctement, elle n'entraîne pas
    l'émission de bromodioxines ni de bromofuranes en quantités
    importantes. Le brûlage inconsidéré de produits contenant du TeBDE
    peut conduire à la formation de PBDF ou de PBDD en quantités
    indéterminées. Dans un futur Critère d'hygiène de l'environnement
    consacré aux PBDF et aux PBDD, l'importance de ce problème pour
    l'homme et l'environnement sera examinée.

    3  Recommandations

    3.1  Recommandations générales

        Du fait de sa rémanence dans l'environnement et de son
    accumulation chez les êtres vivants, il est recommandé de ne pas
    utiliser le TeBDE. Cependant si son usage se poursuit, il faudra
    prendre les précautions suivantes:

    *   Les travailleurs qui sont employés à la production de TeBDE et de
        produits qui en contiennent, doivent être protégés contre toute
        exposition grâce à des mesures appropriées d'hygiène industrielle,
        par la surveillance de l'exposition professionnelle et par des
        mesures techniques adéquates.

    *   Il convient de minimiser l'exposition environnementale par un
        traitement approprié des effluents et des émissions provenant des
        industries qui utilisent ce composé ou des produits qui en
        contiennent. Le rejet des déchets industriels et des produits de
        consommation doit être réglementé afin de réduire au minimum la
        contamination de l'environnement par ce composé persistant et
        cumulatif et ses produits de décomposition.

    *   On ne doit procéder à l'incinération de produits contenant un
        retardateur de flamme à base TeBDE qu'au moyen d'incinérateurs
        convenables fonctionnant toujours dans des conditions optimales.
        Le brûlage des déchets par tout autre moyen risque d'entraîner la
        formation de produits de décomposition principalement formés de
        furanes.

    3.2  Etudes à effectuer

    *   Il importe d'assurer une surveillance permanente des
        concentrations dans l'environnement.

    *   Il faudrait valider les méthodes d'analyse du TeBDE dans diverses
        matrices.

    *   Comme la base de données toxicologiques actuelle est insuffisante
        pour permettre d'évaluer le danger que le TeBDE représente pour
        l'homme et l'environnement, il faudra, si on continue à utiliser
        ce produit, effectuer les travaux suivants:

        -   études toxicologiques et écotoxicologiques supplémentaires et
            études de cancérogénicité;

        -   poursuite des études sur la formation de PBDF dans les
            conditions réelles d'incendie;

        -   étude des méthodes de recyclage des polymères contenant du
            TeBDE et de ses conséquences;

        -   recherches sur la possibilité de migration à partir de
            produits contenant des retardateurs de flamme.

    TRIBROMODIPHENYLETHER

        Le tribromodiphényléther n'est ni produit ni utilisé.

        On ne dispose d'aucune donnée sur les points suivants:

    *   Transport, distribution et transformation dans l'environnement

    *   Cinétique et métabolisme chez les animaux de laboratoire et
        l'homme

    *   Effets sur les mammifères de laboratoire et les systèmes d'épreuve
         in vitro

    *   Effets sur l'homme

    *   Effets sur les autres êtres vivants au laboratoire et dans leur
        milieu naturel

    *   Evaluations antérieures par des organismes internationaux.

    1  Résumé et évaluation

        Il n'existe pas de base de données sur laquelle fonder une
    évaluation.

    2  Recommandations

        Il convient de réduire au minimum la contamination des produits du
    commerce par du tribromodiphényléther afin d'éviter la pollution de
    l'environnement et l'exposition humaine.

        Il faut éviter d'utiliser des produits commerciaux susceptibles
    d'entraîner la pollution du milieu.

    DIBROMODIPHENYLETHER

        Le dibromodiphényléther n'est ni produit ni utilisé.

        On ne dispose d'aucune donnée sur les points suivants:

    *   Cinétique et métabolisme chez les animaux de laboratoire et
        l'homme

    *   Effets sur l'homme

    *   Effets sur les autres êtres vivants au laboratoire et dans leur
        milieu naturel

    *   Evaluations antérieures par des organismes internationaux.

    1  Résumé et évaluation

        Il n'existe pas de base de données sur laquelle fonder une
    évaluation.

    2  Recommandations

        Il convient de réduire au minimum la contamination des produits du
    commerce par du dibromodiphényléther afin d'éviter la pollution de
    l'environnement et l'exposition humaine.

        Il faut éviter d'utiliser des produits commerciaux susceptibles
    d'entraîner la pollution du milieu.

    MONOBROMODIPHENYLETHER

        Il n'existe aucune donnée sur les points suivants:

    *   Cinétique et métabolisme chez les animaux de laboratoire et
        l'homme

    *   Effets sur l'homme

    *   Evaluations antérieures par des organismes internationaux.

    1.  Résumé et évaluation

    1.1  Propriétés physiques et chimiques

        Il y a trois isomères possible du monobromodiphényléther.

        Le  p-bromodiphényléther se présente à la température ambiante
    sous la forme d'un liquide dont le point d'ébullition est de
    305-310°C. Le calcul montre que sa solubilité dans l'eau est de
    48 mg/litre. Le logarithme de son coefficient de partage
     n-octanol/eau se situe entre 4 et. 5. Sa tension de vapeur est de
    0,0015 mmHg à 20°C.

    1.2  Production et usages

        Le MBDE n'est pas utilisé comme retardateur de flamme. Un rapport
    sur sa production est paru en 1977, mais on ne lui connaît pas
    d'usage.

    1.3  Transport, distribution et transformation dans l'environnement

        Sa demi-vie d'évaporation à partir de l'eau est de l'ordre de
    plusieurs centaines de jours.

        Placé dans une culture de 7jours ensemencé avec des micro-
    organismes présents dans des eaux usées domestiques, il ne subit
    pas de biodécomposition importante, mais il est dégradé à 90% dans des
    boues d'égouts activées. D'après la seule étude consacrée à sa
    dégradation par les bactéries terricoles, il semblerait que celles-ci,
    tout au moins une souche particulière, soient incapables d'utiliser le
    MBDE comme seule source de carbone.

    1.4  Concentrations dans r environnement et exposition humaine

        On a décelé la présence de MBDE dans des échantillons d'eau
    superficielle prélevés à proximité de sites industriels aux Etats-Unis
    d'Amérique; toutefois, une enquête analogue menée au Japon n'a pas
    donné de résultats. On en a également décelé aux Etats-Unis d'Amérique
    dans des eaux souterraines à proximité d'une usine. Aux Etats-Unis
    d'Amérique, on a décelé la présence de MBDE dans des sédiments et des
    biotes aquatiques.

    1.5  Cinétique et métabolisme chez les animaux de laboratoire et
         l'homme

        Il n'existe pas de donnée.

    1.6  Effets sur les mammifères de laboratoire et les systèmes d'épreuve
         in vitro

        Le MBDE n'est pas tératogène, mais on ne possède aucune donnée sur
    la toxicité aiguë ni la toxicité à court et à long terme de ce
    composé; aussi est-il impossible de procéder à une évaluation.

    1.7  Effets sur l'homme

        Il n'existe aucune donnée.

    1.8  Effets sur les autres êtres vivants au laboratoire et dans leur
         milieu naturel

        Chez un poisson,  Lepomis macrochirus, la CL50 à 96 heures
    serait de 4,9 mg/litre, avec une concentration sans effets observables
    de moins de 2,8 mg/litre. La CL50 à 48 heures pour la puce d'eau est
    de 0,36 mg/litre avec une concentration sans effets observables de
    moins de 0,046 mg/litre.

    2  Conclusions et recommandations

        Le monobromodiphényléther n'agit pas comme retardateur de flamme.
    Il peut s'accumuler chez les êtres vivants dans leur milieu naturel et
    on en a décelé la présence dans divers secteurs de l'environnement. Il
    semblerait qu'il puisse subir une biodécomposition.

        Ces données sont trop limitées pour qu'on puisse parvenir à des
    conclusions quant aux niveaux d'exposition et aux effets que ce
    composé peut avoir sur la population générale et les êtres vivants
    dans leur milieu naturel.

        Il n'existe aucune base de données toxicologiques qui plaide en
    faveur de l'utilisation de ce produit.

        Il faut éviter toute utilisation susceptible de conduire à une
    pollution de l'environnement.

    RESUMEN, EVALUACIœN, CONCLUSIONES Y RECOMENDACIONES

    ÉTER DE DECABROMODIFENILO

    1.  Resumen y evaluación

    1.1  Identidad y propiedades fisicas y quimicas

        El éter de decabromodifenilo (DeBDE) comercial suele tener una
    pureza del 97-98%, con un 0,3-3,0% de éteres de difenilo nona- y
    octabromados. La impureza mas importante es el éter de
    nonabromodifenilo (NBDE). A diferencia de los otros éteres de difenilo
    polibromados, el DeBDE tiene un solo isomero.

        El punto de fusion es de unos 300°C y la descomposicion se produce
    por encima de los 400°C. La solubilidad en agua es de 20-30 µg/litro y
    el logaritmo del coeficiente de reparto  n-octanol/agua es superior a
    5. La presion de vapor es <10-6 mm de Hg a 20°C.

    1.2  Produccion y aplicaciones

        Entre los éteres de difenilo bromados (del mono- al deca-), el
    éter de decabromodifenilo es el mas importante de fabricacion
    comercial en cuanto a produccion y aplicaciones.

        A partir del decenio de 1970 se ha elaborado DeBDE comercial cada
    vez mas puro. Su produccion mundial es de unas 300 000 toneladas al
    ano. Se utiliza como aditivo pirorretardante en numerosos plasticos,
    sobre todo en el poliestireno de gran resistencia al impacto, en el
    tratamiento de tejidos utilizados en pasamaneria, telas de automoviles
    y tiendas de campana.

    1.3  Transporte, distribucion y transformacion en el medio ambiente

        La fotodegradacion del DeBDE tiene lugar en disolventes organicos
    con radiacion ultravioleta (RUV) o la luz del sol y produce éteres de
    difenilo con un numero menor de atomos de bromo y dibenzofuranos
    bromados. También se produce fotodegradacion, en menor grado, en el
    agua bajo la accion de la luz del sol; sin embargo, no se ha detectado
    la presencia de éteres de difenilo menos bromados ni tampoco de
    dibenzofuranos bromados.

        En funcion del tipo de polimero y del disolvente de extraccion se
    obtiene una concentracion de DeBDE que esta casi en el limite de
    deteccion o es inferior a él.

        Debido a que la solubilidad en agua y la presion de vapor son
    extremadamente bajas, es probable que el transporte del DeBDE se
    produzca sobre todo mediante adsorcion sobre particulas. Es
    persistente y se acumula facilmente en el sedimento y en el suelo.

        No se dispone de datos acerca de su biodisponibilidad a partir del
    sedimento y del suelo. En un estudio realizado en la trucha irisada no
    se detecto bioacumulacion en la carne, la piel o las visceras durante
    mas de 48 horas. No es probable la bioacumulacion del DeBDE, debido a
    su peso molecular relativamente alto.

        A la larga, los productos que contienen DeBDE comercial se
    eliminan en vertederos o mediante incineracion. El DeBDE, en ultimo
    término, se puede lixiviar de los vertederos. Se pueden producir
    dibenzofuranos polibromados (PBDF) y mezclas de dibenzofuranos y
    dibenzodioxinas halogenados en incendios de los vertederos o por una
    incineracion incompleta. Los productos que contienen DeBDE comercial
    pueden contribuir a estas emisiones.

        La pirolisis del propio DeBDE comercial y de los polimeros (HIPS,
    PBT, polipropileno industrial) con DeBDE en presencia de oxigeno
    produjo PBDF, detectandose en menor grado dibenzodioxinas polibromadas
    (PBDD). La formacion maxima de PBDF tiene lugar a 400-500°C, pero se
    puede producir a temperaturas de hasta 800°C; el Sb2O3 ejerce una
    funcion catalitica en la formacion de PBDF y PBDD.

        La formacion de PBDF y PBDD y las cantidades encontradas dependen
    de la temperatura, el contenido de oxigeno y la duracion de la
    pirolisis. En ausencia de oxigeno, se forman sobre todo
    polibromobencenos y polibromonaftalenos.

    1.4  Niveles medioambientales y exposicion humana

        En la vecindad de las instalaciones de fabricacion se han
    identificado concentraciones de DeBDE de hasta 25 µg/m3. No se
    detecto en las muestras de agua recogidas en el Japon durante el
    periodo de 1977-91. Sin embargo, se observo en el sedimento de rios
    recogido en el Japon durante el mismo periodo a concentraciones de
    hasta unos 12 mg/kg de peso seco. En los Estados Unidos se encontro
    DeBDE (hasta 1 g/kg) en el sedimento de los rios cercanos a una
    fabrica. No se detecto su presencia en las muestras de peces recogidas
    en el Japon, aunque en una muestra de mejillones se observo una
    concentracion ligeramente superior al nivel de deteccion. Aunque no se
    encontro en las muestras de tejido adiposo humano recogidas en el
    Japon, en los Estados Unidos se observo en 3 de 5 muestras de este
    tipo de tejido.

        La exposicion humana al DeBDE se puede producir en el curso de la
    fabricacion y la formulacion en polimeros. La exposicion de la
    poblacion general al DeBDE es insignificante.

        En la determinacion de la exposicion en el trabajo a los productos
    de degradacion del DeBDE durante la fabricacion, formulacion o
    utilizacion se puso de manifiesto que las muestras de aire proximas al
    cabezal del extrusor contenian concentraciones elevadas de PBDF. En el
    aire de la sala de trabajo se encontraron niveles mas bajos. Se
    detecto asimismo en muestras del material de limpieza. Se ha
    demostrado que la aplicacion de buenas técnicas industriales reduce la
    exposicion ocupacional al PBDF.

        No es probable una exposicion significativa de la poblacion
    general a las impurezas de PBDF de los polimeros con caracteristicas
    pirorretardantes.

    1.5  Cinética y metabolismo en animales de laboratorio y en el ser
         humano

        El DeBDE tiene una escasa absorcion desde el tracto
    gastrointestinal y se excreta con rapidez tras su inyeccion.

        Los resultados de los estudios metabolicos en ratas utilizando
    DeBDF marcado con 14C indicaron una semivida para su desaparicion del
    organismo de menos de 24 horas, siendo la ruta principal de
    eliminacion tras la ingestion oral la via fecal. En la orina o el aire
    expirado no se encontro una actividad apreciable de 14C (inferior al
    1%).

        Las ratas alimentadas con 0,1 mg/kg de peso corporal al dia,
    durante un periodo de hasta dos anos, no mostraron acumulacion de
    DeBDF en el suero, los rinones, los musculos o los testiculos, como se
    comprobo mediante una determinacion del bromo total. La acumulacion de
    bromo en el higado alcanzo un nivel estacionarlo a los 30 dias y
    desaparecio en un periodo de 10 dias después del tratamiento. Tras
    180 dias de tratamiento, el nivel de bromo en el higado de las ratas
    tratadas no era superior al de las testigo. En el tejido adiposo se
    acumulo una concentracion baja de bromo total, que se mantenia tras
    90 dias con una alimentacion sin DeBDE; se desconoce la naturaleza del
    bromo acumulado. Habida cuenta de que el DeBDE representaba solo el
    77% de la mezcla comercial utilizada, el "bromo" podria proceder del
    NBDE o el OBDE.

    1.6  Efectos en los animales de laboratorio y en sistemas de prueba
         in vitro

        La toxicidad aguda del DeBDE en los animales de laboratorio es
    baja. La sustancia no es irritante para la piel o los ojos de los
    conejos. No es cloracnegénico en la piel de los conejos, ni tampoco
    sensibilizador cutaneo humano.

        Se realizaron pruebas de toxicidad aguda y de comedogenicidad de
    los productos de la combustion del poliestireno pirorretardante con
    DeBDE y Sb2O3. La DL50 por via oral del hollin y la carbonilla fue
    > 2000 mg/kg de peso corporal.

        No se observo induccion de efectos adversos en los estudios de
    toxicidad a cono plazo realizados en ratas y ratones con niveles de
    DeBDE (pureza > 97%) de 100 g/kg (4 semanas) o 50 g/kg de alimentos
    (13 semanas, equivalente a 2500 mg/kg de peso corporal de la rata). En
    un estudio de reproduccion de una sola generacion en ratas no se
    observaron efectos adversos con niveles de dosis de 100 mg/kg de peso
    corporal. El DeBDE no produjo efectos teratogénicos en los fetos de
    las ratas que recibieron dosis de 100 mg/kg de peso corporal. Con
    1000 mg/kg de peso corporal se detectaron malformaciones como el
    retraso de la osificacion. En varias pruebas realizadas no se ha
    observado que tenga efectos mutagénicos.

        En un estudio de carcinogenicidad en ratas y ratones, se
    administraron concentraciones de DeBDE (pureza 94-99%) de hasta
    50 g/kg de alimentos. Se observo un aumento en el numero de adenomas
    hepaticos (pero no de carcinomas) de las ratas macho que recibieron
    25 g/kg y en las ratas hembra con 50 g/kg. En ratones macho tratados
    con 25 g/kg se detecto una frecuencia mayor de adenomas y carcinomas
    hepatocelulares (combinados) y con ambos niveles de dosis un aumento
    de adenomas/carcinomas (combinados) de las células foliculares del
    tiroides. En los ratones hembra no se aprecio ningun incremento de la
    frecuencia de tumores. Se obtuvo una prueba equivoca de
    carcinogenicidad en ratas macho y hembra y en ratones macho solo con
    dosis de 25-50 g de DeBDE/kg de alimentos. Dado que los resultados de
    todas las pruebas de mutagenicidad han sido negativos, se puede
    concluir que el DeBDE carece de carcinogenicidad genotoxica. IARC
    (1990) concluyo que las pruebas de carcinogenicidad del DeBDE en los
    animales de experimentacion eran limitadas. Los niveles de
    dosificacion muy elevados, la falta de genotoxicidad y las pruebas
    minimas de carcinogenicidad ponen de manifiesto que el DeBDE, a las
    concentraciones de exposicion actuales, no representa un riesgo de
    carcinogénesis para el ser humano.

    1.7  Efectos en el ser humano

        No se detectaron signos de sensibilizacion cutanea en una prueba
    realizada con 200 personas expuestas al DeBDE.

        En un estudio de morbilidad realizado con el personal del extrusor
    que mezcla polibutilenterftalato que contiene DeBDE, con la
    consiguiente exposicion potencial al PBDD y al PBDF durante 13 anos,
    no se observaron efectos nocivos, aun cuando se detectaron en sangre
    2,3,7,8-TeBDF y -TeBDD. Los resultados de los estudios inmunologicos
    pusieron de manifiesto que el sistema inmunitario de las personas
    expuestas no se habia visto negativamente afectado después de 13 anos.

    1.8  Efectos en otros organismos en d laboratorio y en el medio
         ambiente

        Las CE50s para el crecimiento de tres algas unicelulares marinas
    fueron superiores a 1 mg de DeBDE/litro. No se dispone de mas
    informacion sobre los efectos del DeBDE en otros organismos en el
    laboratorio y en el medio ambiente.

    2  Conclusiones

    2.1  DeBDE

        El DeBDE se utiliza ampliamente en polimeros como aditivo
    pirorretardante. El contacto de la poblacion general se produce a
    través de productos fabricados con dichos polimeros. La exposicion es
    muy escasa, puesto que no es facil extraer el DeBDE de los polimeros.
    La toxicidad aguda es muy baja y la absorcion del tracto
    gastrointestinal minima. Asi pues, el riesgo para la poblacion general
    se puede considerar insignificante.

        La exposicion en el trabajo se da con el DeBDE en forma de
    particulas. El control del polvo. durante la fabricacion y el empleo
    reducira el riesgo para los trabajadores de manera suficiente.

        El DeBDE es persistente y se une a particulas del medio ambiente;
    es facil que se acumule en el sedimento, pero no es probable su
    bioacumulacion. Aunque las pruebas disponibles indican que la
    fotodegradacion ambiental en agua no producen éteres de difenilo o
    dibenzofuranos con menor numero de atomos de bromo, apenas se conoce
    nada sobre la degradacion en otros medios.

        La informacion sobre la toxicidad del DeBDE para los organismos
    del medio ambiente es minima.

    2.2  Productos de degradacion

        Se puede producir PBDF y, en cierta medida, PBDD cuando se somete
    el DeBDE, o los productos que lo contienen, a temperaturas de
    300-800°C. Hay que estudiar los posibles peligros asociados a estos
    productos.

        La incineracion controlada de manera adecuada no produce una
    emision de cantidades significativas de dioxinas o furanos bromados.
    Cualquier combustion no controlada de productos con DeBDE puede dar
    lugar a una formacion no cuantificada de PBDF/PBDD. De su importancia
    para el ser humano y el medio ambiente se ocupara un futuro numero de
    Criterios de Salud Ambiental.

        Se ha detectado PBDR en la sangre de las personas que trabajan en
    la produccion de plasticos con DeBDE. No se han observado efectos
    adversos relacionados con esta exposicion. Con un buen control técnico
    se puede evitar la exposicion de los trabajadores al PBDF.

    3  Recomendaciones

    3.1  Generales

    *   Las personas que trabajan en la fabricacion de DeBDE y productos
        que lo contienen deben estar protegidas de la exposicion mediante
        la aplicacion de medidas adecuadas de higiene industrial, la
        vigilancia de la exposicion en el trabajo y controles técnicos.

    *   Hay que reducir al minimo la exposicion ambiental mediante el
        tratamiento adecuado de efluentes y emisiones industriales que
        contienen el compuesto o sus productos. Se debe controlar la
        eliminacion de los residuos industriales y los productos de
        consumo para que sea minima la contaminacion del medio ambiente
        con esta sustancia persistente y sus productos de degradacion.

    *   Los fabricantes deben reducir al minimo los niveles de impurezas
        en los productos comerciales de DeBDE, utilizando las mejores
        técnicas disponibles. Se recomienda una pureza del 97% o superior.

    *   La incineracion solo se debe realizar en incineradores adecuados
        que funcionen siempre en condiciones optimas. La quema por otros
        medios puede dar lugar a la formacion de PBDF y PBDD.

    3.2  Otros estudios

    *   Se deberan realizar en los organismos pertinentes nuevos estudios
        sobre la biodisponibilidad y la toxicidad del DeBDE unido al
        sedimento.

    *   Hay que mantener una vigilancia constante de los niveles en el
        medio ambiente.

    *   Se debe investigar con mas detalle la formacion de PBDF en
        incendios reales.

    *   Hay que estudiar mas a fondo la biodegradacion en el medio
        ambiente y la fotodegradacion en compartimentos distintos del
        agua.

    *   Se debe investigar los posibles métodos y las consecuencias del
        reciclaje de polimeros que contienen DeBDE.

    *   Hay que validar métodos analiticos para el DeBDE en diversos
        aglomerantes.

    ÉTER DE NONABROMODIFENILO

        El éter de nonabromodifenilo no se fabrica ni se utiliza. No se
    dispone de datos sobre los aspectos siguientes:

    *   Transporte, distribucion y transformacion en el medio ambiente

    *   Niveles medioambientales y exposicion humana

    *   Cinética y metabolismo en animales de laboratorio y en el ser
        humano

    *   Efectos en los animales de laboratorio y en sistemas de prueba
         in vitro

    *   Efectos en el ser humano

    *   Efectos en otros organismos en el laboratorio y en el medio
        ambiente

    *   Evaluaciones anteriores por parte de organos internacionales.

    1  Resumen y evaluacion

        No hay ninguna base de datos sobre la cual realizar una
    evaluacion.

    2  Recomendaciones

        Los niveles de contaminacion de los pirorretardantes bromados
    comerciales que contienen éter de nonabromodifenilo deberian ser
    minimos a fin de evitar la contaminacion del medio ambiente y la
    exposicion humana.

    ÉTER DE OCTABROMODIFENILO

        El éter de octabromodifenilo puro no se fabrica ni se utiliza. No
    se dispone de datos sobre los aspectos siguientes:

    *   Cinética y metabolismo en animales de laboratorio y en el ser
        humano

    *   Efectos en el ser humano

    *   Efectos en otros organismos en el laboratorio y en el medio
        ambiente

    *   Evaluaciones anteriores por parte de organos internacionales.

    1  Resumen y evaluacion

    1.1  Identificacion y propiedades fisicas y quimicas

        El éter de octabromodifenilo (OBDE) comercial es una mezcla
    formada por alrededor del 11% de PeBDE/HxBDE, 44% de HpBDE, 31-35% de
    OBDE, 10% de NBDE y 0,5% de DeBDE. En funcion de su estructura
    quimica, existen 12 posibles isomeros del OBDE y 24 del HpBDE.

        El punto de fusion oscila entre unos 80°C y >200°C. La presion de
    vapor es <10-7 mm de Hg. La solubilidad en agua es baja y el
    logaritmo del coeficiente de reparto  n-octanol/agua es >5,5. Las
    variaciones anteriores obtenidas en los datos fisicos pueden deberse a
    diferencias de composicion en las mezclas probadas.

    1.2  Produccion y aplicaciones

        El consumo anual de OBDE comercial en todo el mundo es de 6000
    toneladas, el 70% del cual se utiliza como pirorretardante en ABS para
    la produccion de computadores y cabinas comerciales. El OBDE es el
    segundo mas utilizado de los pirorretardantes de PBDE.

    1.3  Transporte, distribucion y transformacion en el medio ambiente

        Se han detectado componentes de OBDE comercial en el sedimento
    acuatico y en la grasa humana. En la biota se han encontrado algunos
    componentes de menor numero de atomos de bromo (HxBDE y PeBDE) del
    producto comercial. No se ha observado OBDE, pero normalmente no se ha
    investigado la presencia de HpBDE y NBDE. Es facil que persistan los
    componentes comerciales de OBDE, pero a medida que el numero de atomos
    de bromo aumenta por encima del HxBDE disminuye la probabilidad de
    bioacumulacion. En la carpa se ha encontrado un factor de
    bioacumulacion inferior a 2 para un producto de OBDE comercial.

        En la pirolisis a 600°C del producto comercial como tal o de
    polimeros que lo contienen como aditivo pirorretardante (con Sb2O3 o
    sin él) se ha puesto de manifiesto la produccion de PBDF y, en grado
    mucho menor, PBDD. El tratamiento de ABS con OBDE/Sb2O3 en
    diferentes condiciones permitio demostrar que, en el caso de
    tratamiento normal, solo se formaban pequenas concentraciones de PBDF.
    En condiciones de uso excesivo, las concentraciones fueron mucho mas
    elevadas. Las concentraciones de PBDD fueron bajas en ambos casos.

    1.4  Niveles medioambientales y exposicion humana

        En una serie de muestras recogidas en el Japon durante 1987 y 1988
    no se detecto OBDE ni los componentes de menor numero de atomos de
    bromo del producto comercial. También se analizaron muestras del
    sedimento y se encontro OBDE en alrededor del 2-6% de las muestras a
    concentraciones que oscilaban entre 8 y 22 µg/kg de peso seco. En el
    sedimento se observo asimismo la presencia de componentes de menor
    numero de atomos de bromo

        No se detecto OBDE en las muestras de peces recogidas en el Japon
    durante 1987 y 1988.

        En los Estados Unidos se investigo la presencia de PBDF Y PBDD en
    muestras de grasa humana recogidas en 1987. Las muestras procedian de
    865 personas combinadas para formar 48 grupos compuestos analogos. La
    composicion se baso en 9 divisiones de censo y 3 grupos de edad. En
    estas muestras también se identifico PBDE y los datos preliminares
    indicaron la presencia de OBDE con una frecuencia del 60% y una
    concentracion estimada de hasta 8000 ng/kg.

    1.5  Cinética y metabolismo en animales de laboratorio y en el ser
         humano

        No se dispone de datos.

    1.6  Efectos en los animales de laboratorio y en los
         sistemas de prueba  in vitro

        La toxicidad aguda del producto comercial en los animales de
    laboratorio es baja. No es irritante cutaneo y solo produce una ligera
    irritacion ocular en los conejos. En los estudios de toxicidad a corto
    plazo (4 semanas y 13 semanas) se observo que en las ratas que
    recibieron dosis de 100 mg/kg de alimentos se produjo un mayor peso
    del higado y cambios microscopicos caracterizados por un aumento de
    tamano de las células parenquimaticas hepaticas de la zona
    centrolobular y media que contienen estructuras granulares. Estos
    cambios hepaticos fueron mas graves con dosis mas elevadas, es decir,
    1000 y 10 000 mg/kg de alimentos. A esto hay que anadir que se observo

    hiperplasia en el tiroides. El contenido total de bromo en los tejidos
    aumento durante el estudio y disminuyo lentamente durante un periodo
    de recuperacion. Los cambios hepaticos fueron reversibles. En un
    estudio de inhalacion con polvo de OBDE micronizado (8 horas al dia
    durante 14 dias consecutivos) no se observaron efectos con
    exposiciones a 1,2 mg/m3, pero a 12 mg/m3 se produjeron en el higado
    los cambios descritos en los estudios de administracion oral.

        El OBDE comercial a dosis relativamente bajas produjo en ratas un
    aumento del citocromo P450 y la induccion de enzimas microsomicas
    hepaticas, como la UDP-glucuronil transferasa y la benzo[alpha]pireno
    hidroxilasa. El OBDE comercial indujo efectos porfirinogénicos en
    cultivos de células hepaticas de embrion de pollo.

        Su potencial teratogénico se probo en ratas; con dosis elevadas
    (25,0 y 50,0 mg/kg de peso corporal) se detectaron procesos de
    resorcion y osificacion retardada de diferentes huesos, asi como
    malformaciones fetales. Las malformaciones observadas tras la
    administracion de dosis de 25 mg/kg de peso corporal y superiores
    probablemente se debieron en buena parte a la toxicidad materna. Estos
    cambios no se advirtieron a dosis de 15,0 mg/kg de peso corporal o
    inferiores. No se obtuvieron pruebas de actividad teratogénica en los
    conejos, pero se observo fetotoxicidad a una dosis toxica para las
    madres de 15 mg/kg de peso corporal. En los estudios de
    teratogenicidad se puso de manifiesto la ausencia de efectos a una
    dosis de 2,5 mg/kg de peso corporal.

        En estudios de 28 dias y 90 dias realizados en ratas se observo
    que 100 mg de OBDE por kg de alimentos (equivalentes a 5 mg/kg de peso
    corporal) producian efectos minimos en el higado. No se establecio un
    nivel sin efectos. Los resultados de las pruebas de mutagenicidad,
    incluso con un ensayo de ADN fuera de programa, los ensayos
    microbiologicos  in vitro y un ensayo de intercambio de cromatidas
    hermanas con células de ovario de hamster chino fueron negativos.

        No se dispone de resultados de pruebas de carcinogenicidad a largo
    plazo.

    1.7  Efectos  en el ser humano

        No se dispone de datos.

    1.8  Efectos en otros organismos en el laboratorio y en el medio
         ambiente

        Los datos disponibles son minimos.

    2  Conclusiones

    2.1  OBDE

        El OBDE comercial es una mezcla de éteres de hexa-,hepta-, octa-,
    y nonabromodifenilo, todos ellos persistentes en el medio ambiente,
    fundamentalmente unidos al sedimento.

        El OBDE se anade con mucha frecuencia a los polimeros como aditivo
    pirorretardante. El contacto de la poblacion general tiene lugar
    mediante los productos fabricados con estos polimeros. No es probable
    la exposicion por extraccion de los polimeros.

        La toxicidad aguda del OBDE es baja. No se dispone de informacion
    sobre su absorcion y eliminacion en los mamiferos. No es teratogénico
    ni mutagénico. No se dispone de estudios de toxicidad y
    carcinogenicidad a largo plazo.

        En el tejido adiposo humano se han identificado varios componentes
    del OBDE comercial. El riesgo grave para la poblacion general
    probablemente es bajo. No es posible evaluar el riesgo de exposicion
    prolongada, debido a la falta de los estudios de toxicidad
    correspondientes.

        La falta de informacion no permite sacar conclusiones sobre la
    exposicion en el trabajo al OBDE o sus efectos.

        La informacion sobre la toxicidad del OBDE para los organismos en
    el medio ambiente es limitada. Los componentes de la mezcla de OBDE
    comercial con menor numero de atomos de bromo podrian dar lugar a una
    bioacumulacion en los organismos.

    2.2  Productos de degradacion

        Puede formarse PBDF, y en cierto grado PBDD, cuando el OBDE o los
    productos que lo contienen se calientan a 400-800°C. Hay que
    investigar los posibles peligros relacionados con esta transformacion.

        No es probable que la exposicion de la poblacion general a las
    impurezas de PBDF en los polimeros pirorretardantes sea significativa.
    La incineracion adecuadamente controlada no deberia producir la
    emision de cantidades importantes de dioxinas y furanos bromados.
    Cualquier combustion no controlada de productos que contienen OBDE
    comercial puede dar lugar a la produccion de cantidades no
    cuantificadas de PBDF/PBDD. Su importancia para el ser humano y el
    medio ambiente sera objeto de estudio en un futuro EHC sobre el
    PBDF/PBDD.

    3  Recomendaciones

    3.1  Generales

    *   En la fabricacion de OBDE comercial se deben utilizar las mejores
        técnicas disponibles, a fin de reducir al minimo los niveles de
        hexabromodifenilo y los compuestos analogos de menor numero de
        atomos de bromo, debido a su posible bioacumulacion en el medio
        ambiente.

    *   Los trabajadores que intervienen en la fabricacion de OBDE y de
        los productos que contienen el compuesto deben estar protegidos de
        la exposicion mediante la aplicacion de medidas de higiene
        industrial adecuadas, la vigilancia de la exposicion en el trabajo
        y controles técnicos.

    *   Se debe reducir al minimo la exposicion ambiental mediante el
        tratamiento adecuado de los efluentes y las emisiones en las
        industrias que utilizan el compuesto o sus productos. Hay que
        controlar la eliminacion de desechos industriales y de los
        productos de consumo, a fin de reducir al minimo la contaminacion
        del medio ambiente con este material persistente y los productos
        de su degradacion.

    *   La incineracion de materiales con aditivos pirorretardantes a base
        de OBDE se debe realizar solo en incineradores adecuados que
        funcionen siempre en condiciones optimas. La combustion por
        cualquier otro medio puede dar lugar a la produccion de PBDF y
        PBDD.

    3.2  Otros estudios

        Habida cuenta de que la base de datos toxicologica actual no es
    adecuada para evaluar los peligros del OBDE comercial para el ser
    humano y el medio ambiente y a fin de mejorar su uso se deberian
    realizar los siguientes estudios:

    *   Investigaciones sobre la biodisponibilidad y la ecotoxicidad de
        los componentes del OBDE comercial unidos al sedimento utilizando
        los organismos pertinentes.

    *   Mayor vigilancia de los niveles en el medio ambiente de los
        componentes de OBDE comercial.

    *   Estudios de toxicidad y carcinogenicidad a largo plazo del OBDE
        comercial.

    *   Vigilancia de la exposicion en el trabajo al OBDE comercial.

    *   Otras investigaciones sobre la formacion de PBDF en incendios
        reales.

    *   Nuevos estudios sobre biodegradacion y fotodegradacion en el medio
        ambiente en compartimentos diferentes del acuatico.

    *   Investigacion de posibles métodos y consecuencias del reciclaje de
        polimeros que contienen OBDE.

    *   Validacion de métodos analiticos para el OBDE en varios
        aglomerantes.

    *   Investigaciones sobre la posibilidad de migracion a partir de
        diferentes tipos de polimeros.

    ÉTER DE HEPTABROMODIFENILO

        El éter de heptabromodifenilo no se fabrica ni se utiliza.

        No existe una base de datos sobre la que hacer una evaluacion del
    HpBDE.

        No se dispone de datos sobre los aspectos siguientes:

    *   Cinética y metabolismo en animales de laboratorio y en el ser
        humano

    *   Efectos en el ser humano

    *   Efectos en otros organismos en el laboratorio y en el medio
        ambiente

    *   Evaluaciones previas por parte de organos internacionales.

        Dado que el HpBDE es el principal componente del éter de
    octabromodifenilo comercial, el resumen, evaluacion, conclusiones y
    recomendaciones del OBDE comercial son aplicables al HpBDE
    "comercial".

    ÉTER DE HEXABROMODIFENILO

        Aunque el éter de hexabromodifenilo no se fabrica ni se utiliza,
    es posible encontrarlo como contaminante de los éteres bromados del
    difenilo comerciales. Se debe reducir al minimo tales niveles del éter
    de hexabromodifenilo para evitar la contaminacion del medio ambiente y
    la exposicion humana.

        No existe una base de datos sobre la que hacer una evaluacion.

        No se dispone de datos sobre los aspectos siguientes:

    *   Efectos en mamiferos de laboratorio y en sistemas de ensayo
         in vitro

    *   Efectos en el ser humano

    *   Efectos en otros organismos en el laboratorio y en el medio
        ambiente

    *   Evaluaciones previas por parte de organos internacionales.

    ÉTER DE PENTABROMODIFENILO

        El éter de pentabromodifenilo no se fabrica ni se utiliza.

        No se dispone de datos sobre los aspectos siguientes:

    *   Efectos en el ser humano

    *   Efectos en otros organismos en el laboratorio y en el medio
        ambiente

    *   Evaluaciones previas por parte de organos internacionales.

    1  Resumen y evaluacion

    1.1  Identificacion y propiedades fisicas y quimicas

        El éter de pentabromodifenilo comercial (PeBDE) es una mezcla de
    éteres de tetra-, penta-, y hexabromodifenilo. Contiene
    aproximadamente un 50-60% de PeBDE y un 24-38% de TeBDE. Habida cuenta
    de su estructura quimica, hay seis posibles isomeros del PeBDE y 42
    del TeBDE. Los productos comerciales parecen estar formados por tres
    componentes principales, a saber, 2,2',4,4',5'-PeBDE, 2,2',4,4'-TeBDE
    y un compuesto analogo no identificado con cinco atomos de bromo.

        El punto de fusion es de -7 a -3°C y el de ebullicion superior a
    200°C. La presion de vapor es baja: <10-7 mm de Hg; la solubilidad
    en agua es insignificante. El log del coeficiente de reparto
     n-octanol/agua es >6.

    1.2  Produccion y aplicaciones

        El PeBDE se utiliza como aditivo de resinas epoxi, resinas
    fenolicas, poliésteres y poliuretano, asi como de materiales textiles.
    El consumo mundial es de unas 4000 toneladas anuales. Es uno de los
    principales éteres bromados del difenilo pirorretardantes comerciales.

    1.3  Transporte, distribucion y transformacion en el medio ambiente

        Se han detectado componentes del PeBDE comercial en muestras de
    biota, sedimento y fangos cloacales. Es facil que sean persistentes y
    tengan capacidad de bioacumulacion. En las carpas se ha encontrado un
    factor de bioacumulacion para el PeBDE superior a 10 000.

        En los estudios de pirolisis con PeBDE comercial se observo la
    formacion de PBDF y PBDD. La temperatura optima de formacion oscilo
    entre 700-800°C. Cuando la pirolisis de PeBDE tenia lugar en ausencia
    de oxigeno se formaban polibromobencenos, polibromofenoles y PBDF.

    1.4  Niveles medioambientales y exposicion humana

        En muestras obtenidas de rios y estuarios del Japon se detectaron
    niveles que variaban entre la ausencia de PeBDE (<2 µg/kg) y 28 µg/kg
    de peso seco. En Suecia, la concentracion en muestras de sedimento de
    algunos rios alcanzo un valor de hasta 1200 µg de
    2,2',4,4',5'-PeBDE/kg. También en el analisis de fangos cloacales de
    Suecia se puso de manifiesto la presencia de PeBDE.

        En los mejillones y peces recogidos en diferentes costas del Japon
    durante el periodo de 1981-85 se encontraron concentraciones de 0,4 y
    2,8 µg de PeBDE/kg de peso humedo de dos de cinco muestras de
    mejillones. No se detecto PeBDE en los peces (limite de determinacion
    <0,2 µg/kg). Se informo de concentraciones de 1,922 µg/kg de peso
    fresco en muestras de higado de bacalao procedente del mar del Norte.
    En Suecia se encontraron concentraciones de 7,2 a 64 µg de
    2,2',4,4',5'-PeBDE/kg de grasa en corégonos de agua dulce y en
    arenques recogidos en diversos lugares.

        En una mezcla de grasa de focas oceladas y locas grises
    recolectada en Suecia entre 1979 y 1985 se encontro una concentracion
    media de 1,7 µg y 40 µg de 2,2',4,4',5'-PeBDE/kg de grasa,
    respectivamente.

        En mezclas de muestras de musculo de conejo y raton y en muestras
    de sebo de reno recogidas en Suecia de 1985 a 1986 se determino una
    concentracion <0,3 µg, 0,64 µg y 0,26 µg de 2,2',4,4',5'-PeBDE/kg de
    grasa, respectivamente.

        Las muestras de musculo de quebrantahuesos recogidas en Suecia en
    1982-86 contenian una concentracion media de 140 µg de
    2,2',4,4',5'-PeBDE/kg de grasa.

        En los ultimos decenios se han multiplicado por diez los niveles
    de dos isomeros del PeBDE en los huevos de arao del Baltico. La
    concentracion de dichos isomeros en los lucios de un lago de la region
    meridional de Suecia también ha experimentado un aumento (del
    cuadruple). Se ha observado asimismo un aumento considerable en los
    muestreos realizados en el sedimento del Baltico en distintos anos
    durante el ultimo decenio.

        Aunque se dispone de una informacion muy escasa sobre la
    exposicion humana, una estimacion aproximada de la exposicion de la
    poblacion sueca a través del consumo de pescado parece indicar una
    absorcion diaria de 0,1 µg de PeBDE/persona.

    1.5  Cinética y metabolismo en animales de laboratorio y en el ser
         humano

        La semivida del PeBDE solo se ha investigado en la grasa
    perirrenal de ratas. La semivida media oscilo entre 25 y 47 dias, en
    funcion del sexo del animal y del tipo de isomero.

    1.6  Efectos en mamiferos de laboratorio y en sistemas de ensayo
          in vitro

        La toxicidad aguda por via oral del PeBDE comercial en ratas es
    baja; la toxicidad dérmica en conejos es también escasa. La exposicion
    de ratas a inhalacion durante periodos breves y la aplicacion de PeBDE
    al saco conjuntival de conejos produjo solo efectos transitorios
    leves.

        En los estudios de toxicidad a corto plazo realizados en ratas
    (4 y 13 semanas), las concentraciones de 100 mg/kg de alimentos
    produjeron un aumento del peso del higado y ligeras alteraciones
    histologicas. Los cambios consistieron en el agrandamiento de las
    células parenquimaticas hepaticas, que tenian un aspecto granular y
    contenian "cuerpos redondos" eosinofilos. Se produjo en el higado un
    aumento de la cantidad total de bromo dependiente de la dosis y los
    niveles se mantuvieron durante un periodo largo, de hasta 24 semanas.
    Se observo una hiperplasia tiroidea ligera de caracter reversible.

        Tras la administracion oral de PeBDE en dosis diarias bajas, del
    orden de 0,78 µmoles/kg de peso corporal, se detecto la induccion de
    enzimas hepaticas y un aumento de concentracion del citocromo P450.
    Los resultados de la pruebas de teratogenicidad y mutagenicidad fueron
    negativos.

        No se ha informado de estudios de carcinogenicidad a largo plazo.

    1.7  Efectos en el ser humano

        No se dispone de datos.

    1.8  Efectos en otros organismos en el laboratorio y en el medio
         ambiente

        Se dispone de muy pocos datos.

    2  Conclusiones

    2.1  PeBDE

        El PeBDE comercial (mezcla de varios éteres: 24-38% de tetra-,
    50-60% de penta- y 4-8% de hexabromodifenilo) es persistente y se
    acumula en los organismos y en el medio ambiente.

        El PeBDE comercial de utiliza ampliamente incorporado a polimeros
    como aditivo pirorretardante. El contacto de la poblacion general
    tiene lugar a través de los productos fabricados con estos polimeros.
    No es probable la exposicion debida a su extraccion de ellos. Se puede
    producir exposicion humana al PeBDE mediante la cadena alimentaria,
    puesto que se ha detectado su presencia en organismos del medio
    ambiente que son articulos alimenticios humanos, como peces,
    crustaceos, etc. En los dos ultimos decenios se han determinado
    cantidades crecientes en los peces y las aves de Suecia.

        La toxicidad aguda del PeBDE comercial es baja. No se dispone de
    informacion acerca de su absorcion y eliminacion en los mamiferos.
    Tampoco se han realizado estudios sobre la reproduccion, la toxicidad
    a largo plazo y la carcinogenicidad.

        De los datos disponibles no se puede determinar el riesgo de la
    poblacion general.

        Se carece de la informacion necesaria para sacar conclusiones
    sobre los niveles de exposicion en el trabajo o los efectos del PeBDE
    comercial.

        Se dispone de una informacion limitada sobre la toxicidad del
    PeBDE comercial para los organismos en el medio ambiente.

    2.2  Productos de degradacion

        Al calentar el PeBDE (o los productos que lo contienen) a
    400-800°C se producen PBDF, y en cierta medida el PBDD. Habria que
    ocuparse de los posibles peligros derivados de su formacion.

        La exposicion de la poblacion general al PBDF de los polimeros
    pirorretardantes con PeBDE probablemente carece de importancia. La
    incineracion controlada de forma adecuada no produce una emision de
    cantidades significativas de dioxinas y furanos bromados. La
    combustion no controlada de productos con PeBDE puede dar lugar a la
    formacion de cantidades no cuantificadas de PBDF/PBDD. En un futuro
    EHC sobre PBDF y PBDD se prestara atencion a su importancia para el
    ser humano y el medio ambiente.

    3  Recomendaciones

    3.1  Generales

        Dada su persistencia en el medio ambiente y la acumulacion en
    organismos no se deberia utilizar PeBDE comercial. Sin embargo, si se
    va a seguir usando hay que tener en cuenta los puntos siguientes:

    *   Se debe proteger de la exposicion a los trabajadores que
        intervienen en la fabricacion de PeBDE y de los productos que
        contienen el compuesto mediante medidas adecuadas de higiene
        industrial, vigilancia de la exposicion en el trabajo y controles
        técnicos.

    *   Hay que reducir al minimo la exposicion ambiental mediante el
        tratamiento adecuado de efluentes y emisiones de las industrias
        que utilizan el compuesto o sus productos. Se debe controlar la
        eliminacion de desechos industriales y de productos de consumo
        para evitar en lo posible la contaminacion del medio ambiente con
        este producto persistente y acumulable, asi como con sus productos
        de degradacion.

    *   La incineracion de materiales pirorretardantes con PeBDE solo se
        debe realizar en incineradores adecuados que funcionen siempre en
        condiciones optimas. La quema por otros medios dara lugar a la
        formacion de productos de descomposicion toxicos.

    3.2  Otros estudios

    *   Se requiere una vigilancia permanente de sus niveles en el medio
        ambiente.

    *   Se deben validar métodos de determinacion del PeBDE en diversos
        aglomerantes.

    *   Habida cuenta de que la base de datos toxicologicos actual no es
        adecuada para evaluar los peligros del PeBDE comercial para el ser
        humano y el medio ambiente y, a fin de mejorar su uso, se deberian
        realizar los siguientes estudios:

        -   estudios adicionales toxicologicos, carcinogénicos y
            ecotoxicologicos;

        -   nuevas investigaciones sobre la formacion de PBDF en
            condiciones de incendios reales;

        -   investigacion de posibles métodos de reciclaje de polimeros
            que contienen PeBDE y sus consecuencias;

        -   investigaciones sobre la posibilidad de migracion a partir de
            diferentes tipos de polimeros.

    ÉTER DE TETRABROMODIFENILO

        El éter de tetrabromodifenilo no se fabrica ni se utiliza.

        No se dispone de datos sobre los aspectos siguientes:

    *   Efectos en mamiferos de laboratorio y en sistemas de ensayo
         in vitro

    *   Efectos en el ser humano

    *   Efectos en otros organismos en el laboratorio y en el medio
        ambiente

    *   Evaluaciones previas por parte de organos internacionales

    1  Resumen y evaluacion

    1.1  Identificacion y propiedades fisicas y quimicas

        El éter de tetrabromodifenilo comercial esta formado por una
    mezcla de éteres: 41% de tetra-, 45% de penta- y 7% de
    hexabromodifenilo y alrededor del 7% de PBDE de estructura
    desconocida. En funcion de su estructura quimica, hay 42 posibles
    isomeros del éter de tetrabromodifenilo. Practicamente se carece de
    datos sobre sus propiedades fisicas y quimicas, a excepcion del
    logaritmo del coeficiente de reparto  n-octanol/agua, que es
    5,87-6,16.

    1.2  Produccion y aplicaciones

        Hay un informe de la produccion (utilizacion) de unas 1000
    toneladas de TeBDE en el Japon en 1987. No se tiene conocimiento de
    produccion alguna en la actualidad como éter de tetrabromodifenilo,
    pero esta presente en el éter de pentabromodifenilo comercial en
    cantidades que oscilan entre el 24 y el 38%.

    1.3  Transporte, distribucion y transformacion en el medio ambiente

        En muestras de biota, sedimento y fangos cloacales se han
    encontrado componentes del TeBDE comercial. Es probable que éstos (con
    cantidades aproximadamente iguales de PeBDE) sean persistentes y
    bioacumulables.

        En estudios de pirolisis con TeBDE comercial se puso de manifiesto
    que a 800°C se formaban PBDF y PBDD. No se encontraron estos
    compuestos con mas atomos de bromo.

    1.4  Niveles medioambientales y exposicion humana

        Se detecto TeBDE en el sedimento de rios del Japon en
    concentraciones de 12-31 µg/kg de peso seco y en Suecia a niveles de
    hasta 840 µg/kg de pérdida por incineracion. También se encontro TeBDE
    en fangos cloacales de Suecia a concentraciones de 15 µg/kg.

        Los mejillones y peces recogidos en diferentes lugares del Japon
    contenian TeBDE en concentraciones que oscilaban entre <0,1 y 14,6 µg
    de 2,2',4,4'-TeBDE/kg de peso seco. En Suecia se recogieron diferentes
    tipos de peces en diversos rios para analizar la concentracion de
    2,2',4,4'-TeBDE. Las concentraciones medias variaron entre la no
    detectable (<0,1 mg/kg) y 110 mg/kg de grasa. En los analisis se puso
    de manifiesto la existencia de por lo menos una fuente local de
    contaminacion en un rio determinado. Los corégonos, las truchas
    alpinas y los arenques recogidos en distintos lugares de Suecia en
    1986-87 contenian concentraciones de 15, 400 y 59-450 µg de
    2,2',4,4'-TeBDE/kg de grasa respectivamente. Los peces recogidos en
    rios de Alemania contenian hasta 1 mg de TeBDE/kg de grasa.

        En el arenque y en el higado de bacalao procedentes de las
    regiones meridional, central y septentrional del mar del Norte durante
    el periodo 1983-89, se encontro una tendencia decreciente en la
    concentracion del TeBDE en direccion sur-norte. En el arenque se
    detectaron concentraciones de 8,4-100 µg de 2,2',4,4'-TeBDE/kg de
    grasa.

        En el tejido muscular de aves que se reproducen e invernan en el
    mar Baltico, el mar del Norte y Spitzbergen se determinaron
    concentraciones de 80 a 370 µg de 2,2',4,4'-TeBDE/kg de grasa. Los
    quebrantahuesos recogidos en Suecia entre 1982 y 1986 contenian
    concentraciones medias de 1800 µg/kg de grasa.

        Se ha indicado que hay una tendencia creciente de las
    concentraciones de 2,2',4,4'-TeBDE en los sedimentos del mar Baltico,
    los peces de agua dulce y los huevos de aves marinas de Suecia.

        En la grasa de las focas recogidas en el mar Baltico y en
    Spitzbergen se determinaron concentraciones de 10-73 µg de
    2,2',4,4'-TeBDE/kg de grasa. El perfil cromatografico del PBDE fue
    semejante al del Bromkal 70-5. En mezclas de muestras de grasa de
    focas oceladas y focas grises recogidas en Suecia en 1979-85 se
    encontraron concentraciones de 47 µg y 650 µg de 2,2',4,4'-TeBDE/kg de
    grasa, respectivamente.

        Las mezclas de muestras de musculo de mamiferos terrestres, por
    ejemplo conejos, ratones y renos, recogidas en Suecia en 1985 y 1986
    pusieron de manifiesto concentraciones medias de <2, 0,82 y 0,18 µg
    de 2,2',4,4'-TeBDE/kg de grasa, respectivamente.

        En cuatro muestras de leche de vaca recogidas en Alemania se
    encontraron niveles de 2,5-4,5 µg de PBDE/kg de grasa, medida como
    Bromkal 70DE. En la leche de 25 mujeres de Alemania se encontro PBDE,
    como Bromkal 70DE, en concentraciones que oscilaron entre
    6,2 y 11,1 µg/kg de grasa.

        Una estimacion aproximada de la exposicion a través del consumo de
    pescado entre la poblacion sueca parece indicar una absorcion diaria
    de 0,3 µg de TeBDE/persona.

    1.5  Efectos en los mamiferos de laboratorio y en los sistemas de
         ensayo  in vitro

        No hay datos sobre el propio TeBDE, pero se dispone de datos sobre
    toxicidad aguda y a corto plazo del PeBDE comercial con un contenido
    de TeBDE del 41%.

    1.6  Cinética y metabolismo en animales de laboratorio y en el ser
         humano

        Se dispone de muy pocos datos.

    1.7  Efectos en el ser humano

        Se carece de datos.

    1.8  Efectos en otros organismos de laboratorio y del medio ambiente

        Se carece de datos.

    2  Conclusiones

    2.1  TeBDE

        Los componentes del TeBDE comercial (una mezcla de un 41% de
    2,2',4,4'-tetra-; 45% de 2,2',4,4',5'-penta-; 7% de hexa-; y 7-8% de
    éteres de difenilo polibromados de estructura desconocida) son
    persistentes y se acumulan en organismos del medio ambiente.

        El TeBDE, como componente del éter de pentabromodifenilo, se
    incorpora con profusion a polimeros como aditivo pirorretardante. El
    contacto de la poblacion general se produce a través de productos
    fabricados con estos polimeros. No es probable la exposicion por
    extraccion a partir de los mismos. Es posible la exposicion humana al
    TeBDE, mediante la cadena alimentaria, porque se ha detectado su
    presencia en organismos del medio ambiente que forman parte de la
    alimentacion humana, como por ejemplo peces, crustaceos, etc. Durante
    los dos ultimos decenios se han determinado concentraciones crecientes
    en los peces y las aves de Suecia.

        Apenas se dispone de informacion acerca de la
    toxicidad/carcinogenicidad a corto y largo plazo y de estudios de
    reproduccion.

        No se puede determinar el riesgo para la poblacion general en
    funcion de los datos disponibles.

        No se dispone de la informacion necesaria para poder sacar
    conclusiones sobre los niveles de exposicion en el trabajo o los
    efectos del TeBDE.

        Tampoco hay datos acerca de la toxicidad del TeBDE comercial para
    los organismos del medio ambiente.

    2.2  Productos de degradacion

        Cuando el TeBDE se calienta a 800°C se forman PBDF y PBDD. Hay que
    prestar atencion a los posibles peligros relacionados con éstos.

        La exposicion de la poblacion general al PBDF de los polimeros
    pirorretardantes con TeBDE probablemente carece de importancia. La
    incineracion con los controles adecuados no produce una emision de
    cantidades importantes de dioxinas y furanos bromados. Cualquier
    combustion sin control de productos que contienen TeBDE puede dar
    lugar a la formacion de cantidades no cuantificadas de PBDF/PBDD. Un
    futuro numero de EHC se ocupara de su importancia para el ser humano y
    el medio ambiente.

    3  Recomendaciones

    3.1  Generales

        Dada su persistencia en el medio ambiente y la acumulacion en
    organismos, se recomienda que no se utilice TeBDE. Sin embargo, si se
    va a seguir usando hay que tener en cuenta los puntos siguientes:

    *   Se debe proteger de la exposicion a los trabajadores que
        intervienen en la fabricacion de TeBDE y de los productos que
        contienen el compuesto, mediante medidas adecuadas de higiene
        industrial, vigilancia de la exposicion en el trabajo y controles
        técnicos.

    *   Hay que reducir al minimo la exposicion ambiental mediante el
        tratamiento adecuado de efluentes y emisiones de las industrias
        que utilizan el compuesto o sus productos. Se debe controlar la
        eliminacion de desechos industriales y de productos de consumo
        para evitar en lo posible la contaminacion del medio ambiente con
        este producto persistente y acumulable, asi como con sus productos
        de degradacion.

    *   La incineracion de materiales pirorretardantes con TeBDE solo se
        debe realizar en incineradores adecuados que funcionen siempre en
        condiciones optimas. La quema por otros medios dara lugar a la
        formacion de productos de degradacion del furano toxicos.

    3.2  Otros estudios

    *   Se requiere una vigilancia permanente de sus niveles en el medio
        ambiente.

    *   Se deben validar métodos de determinacion del TeBDE en diversos
        aglomerantes.

    *   Habida cuenta de que la base de datos toxicologicos actual no es
        adecuada para evaluar los peligros del TeBDE comercial para el ser
        humano y el medio ambiente, si se va a continuar con su uso se
        deberian realizar los siguientes estudios:

        -   estudios adicionales toxicologicos, carcinogénicos y
            ecotoxicologicos;

        -   nuevas investigaciones sobre la formacion de PBDF en
            condiciones de incendios reales;

        -   investigacion de posibles métodos de reciclaje de polimeros
            que contienen TeBDE y sus consecuencias;

        -   investigaciones sobre la posibilidad de migracion a partir de
            diferentes tipos de polimeros.

    ÉTER DE TRIBROMODIFENILO

        El éter de tribromodifenilo no se fabrica ni se utiliza. No se
    dispone de datos sobre los aspectos siguientes:

    *   Transporte, distribucion y transformacion en el medio ambiente

    *   Cinética y metabolismo en animales de laboratorio y en el ser
        humano

    *   Efectos en mamiferos de laboratorio y en sistemas de ensayo
         in vitro

    *   Efectos en el ser humano

    *   Efectos en otros organismos en el laboratorio y en el medio
        ambiente

    *   Evaluaciones anteriores por parte de organos internacionales.

    1  Resumen y evaluacion

        No hay una base de datos sobre la cual realizar una evaluacion.

    2  Recomendaciones

        Se debe reducir al minimo la contaminacion de los productos
    comerciales con éter de tribromodifenilo, a fin de evitar la del medio
    ambiente y la exposicion humana.

        Hay que evitar el uso de los productos comerciales capaces de
    contaminar el medio ambiente.

    ÉTER DE DIBROMODIFENILO

        El éter de dibromodifenilo no se fabrica ni se utiliza.

        No se dispone de datos sobre los aspectos siguientes:

    *   Cinética y metabolismo en animales de laboratorio y en el ser
        humano

    *   Efectos en el ser humano

    *   Efectos en otros organismos en el laboratorio y en el medio
        ambiente

    *   Evaluaciones anteriores por parte de organos internacionales.

    1  Resumen y evaluacion

        No hay una base de datos sobre la cual realizar una evaluacion.

    2  Recomendaciones

        Se debe reducir al minimo la contaminacion de los productos
    comerciales con éter de dibromodifenilo, a fin de evitar la del medio
    ambiente y la exposicion humana.

        Hay que evitar el uso de los productos comerciales capaces de
    contaminar el medio ambiente.

    ÉTER DE MONOBROMODIFENILO

        No se dispone de datos sobre los aspectos siguientes:

    *   Cinética y metabolismo en animales de laboratorio y en el ser
        humano

    *   Efectos en el ser humano.

    *   Evaluaciones anteriores por parte de organos internacionales.

    1  Resumen y evaluacion

    1.1  Propiedades fisicas y quimicas

        El éter de monobromodifenilo tiene tres posibles isomeros.

        El éter de  p-bromodifenilo a temperatura ambiente es un liquido
    con un punto de ebullicion de 305-310°C. Se estima que su solubilidad
    en agua es de 48 mg/litro. El log del coeficiente de reparto
     n-octanol/agua es de 4 a 5. La presion de vapor a 20°C es de
    0,0015 mm de Hg.

    1.2  Produccion y aplicaciones

        El MBDE no se utiliza como pirorretardante. En 1977 aparecio un
    informe sobre su produccion, pero se desconoce su empleo.

    1.3  Transporte, distribucion y transformacion en el medio ambiente

        La semivida de volatizacion a partir del agua es del orden de
    centenares de dias.

        Aunque el MBDE no se degrado de manera significativa en un cultivo
    de siete dias con microorganismos de las aguas residuales domésticas,
    se ha informado que en los fangos cloacales activados lo hace en un
    95%. En un estudio aislado se puso de manifiesto que una cepa de
    bacterias del suelo no era capaz de degradar el MBDE como unica fuente
    de carbono.

    1.4  Niveles medioambientales y exposicion humana

        Se ha detectado MBDE en muestras de agua superficial recogidas en
    las cercanias de zonas industriales de los Estados Unidos, pero no se
    obtuvieron estos resultados en un estudio semejante realizado en el
    Japon. Se encontro asimismo en agua del suelo de un lugar proximo a
    una instalacion industrial de los Estados Unidos. También se ha
    detectado en el sedimento acuatico y en la biota acuatica de los
    Estados Unidos.

    1.5  Cinética y metabolismo en animales de laboratorio y en el ser
         humano

        No se dispone de datos.

    1.6  Efectos en mamiferos de laboratorio y en sistemas de ensayo
          in vitro

        El MBDE no es teratogénico, pero se carece de datos sobre su
    toxicidad aguda, a corto plazo y a largo plazo, y por consiguiente no
    se puede realizar su evaluacion.

    1.7  Efectos en el ser humano

        No se dispone de datos.

    1.8  Efectos en otros organismos en el laboratorio y en el medio
         ambiente

        Se ha informado que la CL50 en 96 h para  Lepomis macrochirus es
    de 4,9 mg/litro, con una concentracion sin efectos observados de menos
    de 2,8 mg/litro. La CL50 en 48 horas para la pulga de agua fue de
    0,36 mg/litro, con un NOEC de menos de 0,046 mg/litro.

    2  Conclusiones y recomendaciones

        El éter de monobromodifenilo no tiene propiedades
    pirorretardantes. Puede acumularse en los organismos del medio
    ambiente y se ha detectado en diferentes compartimentos ambientales.
    Algunas pruebas indican que es biodegradable.

        La reducida informacion de que se dispone impide sacar
    conclusiones sobre los niveles de exposicion y los efectos sobre la
    poblacion general y los organismos.

        No existe una base de datos toxicologicos que apoye su uso.

        Se debe evitar todo empleo que provoque la contaminacion del medio
    ambiente.
    


    See Also:
       Toxicological Abbreviations