INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY
ENVIRONMENTAL HEALTH CRITERIA 131
DIETHYLHEXYL PHTHALATE
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.
Published under the joint sponsorship of
the United Nations Environment Programme,
the International Labour Organisation,
and the World Health Organization
First draft prepared by Dr P. Lundberg, Dr. J. Hogberg,
and Dr P. Garberg, National Institute of Occupational
Health, Sweden, Dr I. Lundberg, Karolinska
Hospital, Sweden, and Dr S. Dobson and Mr. P. Howe,
Institute of Terrestrial Ecology, United Kingdom
World Health Orgnization
Geneva, 1992
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WHO Library Cataloguing in Publication Data
Diethylhexyl phthalate.
(Environmental health criteria ; 131)
1.Diethylhexyl phthalate - adverse effects 2.Diethylhexyl
phthalate - toxicity 3.Environmental exposure I.Series
ISBN 92 4 157131 4 (NLM Classification: QV 612)
ISSN 0250-863X
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CONTENTS
ENVIRONMENTAL HEALTH CRITERIA FOR DIETHYLHEXYL PHTHALATE
1. SUMMARY
1.1 Identity, physical and chemical properties, and
analytical methods
1.2 Sources of human and environmental exposure
1.3 Environmental transport, distribution, and
transformation
1.4 Environmental levels and human exposure
1.5 Kinetics and metabolism
1.6 Effects on laboratory mammals and in vitro test
systems
1.7 Effects on humans
1.8 Effects on other organisms in the laboratory
and field
1.9 Evaluation
2. IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES,
AND ANALYTICAL METHODS
2.1 Identity
2.2 Physical and chemical properties
2.3 Conversion factors
2.4 Analytical methods
3. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE
3.1 Natural occurrence
3.2 Anthropogenic sources
3.2.1 Production levels
3.2.2 Uses
3.2.3 Disposal of plasticized products
4. ENVIRONMENTAL TRANSPORT, DISTRIBUTION,
AND TRANSFORMATION
4.1 Environmental transport and distribution
4.1.1 Transport in air
4.1.2 Transport in soil and sediment
4.1.3 Transport in water
4.1.4 Transport between media
4.2 Biotransformation
4.2.1 Abiotic degradation
4.2.2 Biodegradation
4.2.2.1 Aerobic degradation
4.2.2.2 Anaerobic degradation
4.2.3 Bioaccumulation
4.2.3.1 Model ecosystems
4.2.3.2 Aquatic invertebrates
4.2.3.3 Fish
4.2.3.4 Amphibians
4.2.3.5 Plants
4.2.3.6 Birds
5. ENVIRONMENTAL LEVELS AND EXPOSURE
5.1 Environmental levels
5.1.1 Air
5.1.2 Precipitation
5.1.3 Water
5.1.4 Sediment
5.1.5 Soil
5.1.6 Food
5.1.7 Aquatic organisms
5.1.8 Terrestrial organisms
5.2 General population exposure
5.3 Occupational exposure during manufacture,
formulation or use
6. KINETICS AND METABOLISM IN LABORATORY ANIMALS AND HUMANS
6.1 Absorption
6.1.1 Inhalation
6.1.2 Dermal
6.1.3 Oral
6.1.4 Intraperitoneal
6.2 Distribution
6.3 Metabolism
6.4 Elimination and excretion
6.5 Retention and turnover
6.5.1 Half-life and body burden
6.5.2 Indicator media
7. EFFECTS ON LABORATORY MAMMALS AND IN VITRO TEST SYSTEMS
7.1 Single exposure
7.2 Short-term exposure
7.3 Long-term exposure
7.4 Skin and eye irritation; sensitization
7.5 Reproduction, embryotoxicity, and teratogenicity
7.5.1 Reproduction
7.5.2 Embryotoxicity and teratogenicity
7.6 Mutagenicity and related end-points
7.6.1 Mutation
7.6.1.1 Bacteria
7.6.1.2 Fungi
7.6.1.3 Mammalian cells
7.6.1.4 Drosophila
7.6.2 DNA damage
7.6.3 DNA binding
7.6.4 Chromosomal effects
7.6.5 Cell transformation
7.6.6 In vivo effects
7.7 Carcinogenicity
7.8 Special studies
7.9 Mechanisms of hepatotoxicity
8. EFFECTS ON HUMANS
8.1 General population exposure
8.2 Occupational exposure
9. EFFECTS ON OTHER ORGANISMS IN THE LABORATORY AND FIELD
9.1 Toxicity to microorganisms
9.2 Toxicity to aquatic organisms
9.2.1 Invertebrates
9.2.2 Fish
9.2.3 Amphibians
9.3 Toxicity to terrestrial organisms
9.3.1 Plants
9.3.2 Earthworms
9.3.3 Insects
9.3.4 Birds
10. EVALUATION OF HUMAN HEALTH RISKS AND EFFECTS ON THE ENVIRONMENT
10.1 Evaluation of human health risks
10.1.1 Exposure levels
10.1.2 Toxic effects
10.1.3 Conclusion
10.2 Evaluation of effects on the environment
10.2.1 Exposure levels
10.2.2 Toxic effects
10.2.3 Conclusion
11. RECOMMENDATIONS FOR PROTECTION OF HUMAN HEALTH AND THE
ENVIRONMENT
12. FURTHER RESEARCH
13. PREVIOUS EVALUATIONS BY INTERNATIONAL BODIES
REFERENCES
RESUME
RESUMEN
WHO TASK GROUP ON ENVIRONMENTAL HEALTH
CRITERIA FOR DIETHYLHEXYL PHTHALATE
Members
Dr D. Anderson, British Industrial Biological Research Association,
Carshalton, Surrey, United Kingdom
Dr R. Cattley, Department of Experimental Pathology and Toxicology,
Chemical Industry Institute of Toxicology, Research Triangle Park,
North Carolina, USA
Dr U. Chantharaksri, Department of Pharmacology, Mahidol University,
Bangkok, Thailand
Dr S.D. Gangolli, British Industrial Biological Research Association,
Carshalton, Surrey, United Kingdom
Dr J. Högberg, Department of Toxicology, National Institute of
Occupational Health, Solna, Sweden
Mr P. Howe, Institute of Terrestrial Ecology, Monks Wood Experimental
Station, Abbots Ripton, Huntingdon, United Kingdom
Dr F. Matsumura, Toxic Substances Program, Department of Environmental
Toxicology, University of California, Davis, California, USA
(Chairman)
Dr S. Oishi, Department of Toxicology, Metropolitan Research
Laboratory of Public Health, Tokyo, Japan
Dr C.-N. Ong, Department of Community, Occupational and Family
Medicine, National University of Singapore, Singapore (Joint
Rapporteur)
Professor G. Pliss, Laboratory for Chemical Carcinogenic Agents, N.N.
Petrov Research Institute of Oncology, Leningrad, USSR
Professor Y.-L. Wang, Department of Occupational Health, School of
Public Health, Shanghai Medical University, Shanghai, China
Mr G. Welter, Federal Environmental Protection Agency, Berlin, Germany
Representatives of other intergovernmental organizations
Dr M. De Smedt, Commission of the European Communities, Luxembourg
Representatives of non-governmental organizations
Dr C. Elcombe, European Chemical Industry Ecology and Toxicology
Centre, Brussels, Belgium
Dr B. Lake, Conseil Européen des Fédérations de l'Industrie chimique
(CEFIC), Brussels, Belgium
Secretariat
Dr B.-H. Chen, International Programme on Chemical Safety, World
Health Organization, Geneva, Switzerland (Secretary)
Dr P. Lundberg, Department of Toxicology, National Institute of
Occupational Health, Solna, Sweden (Joint Rapporteur)
Dr D. McGregor, International Agency for Research on Cancer, World
Health Organization, Lyon, France
NOTE TO READERS OF THE CRITERIA MONOGRAPHS
Every effort has been made to present information in the criteria
monographs as accurately as possible without unduly delaying their
publication. In the interest of all users of the environmental health
criteria monographs, readers are kindly requested to communicate any
errors that may have occurred to the Manager of the International
Programme on Chemical Safety, World Health Organization, Geneva,
Switzerland, in order that they may be included in corrigenda.
* * *
A detailed data profile and a legal file can be obtained from the
International Register of Potentially Toxic Chemicals, Palais des
Nations, 1211 Geneva 10, Switzerland (Telephone No. 7988400 or
7985850).
ENVIRONMENTAL HEALTH CRITERIA FOR
DIETHYLHEXYL PHTHALATE
A WHO Task Group on Environmental Health Criteria for Diethylhexyl
Phthalate (DEHP) met at the British Industrial Biological Research
Association (BIBRA), Carshalton, Surrey, United Kingdom, from 3 to 7
June 1991. Dr S.D. Gangolli opened the meeting on behalf of BIBRA.
Dr B.-H. Chen, IPCS, welcomed the participants on behalf of the
Manager, IPCS, and the three IPCS cooperating organizations
(UNEP/ILO/WHO). The Task Group reviewed and revised the draft
criteria monograph and made an evaluation of the risks for human
health and the environment from exposure to DEHP.
The first draft of this monograph was prepared by Dr P. Lundberg,
Dr J. Högberg, and Dr P. Garberg of the National Institute of
Occupational Health, Sweden, Dr I. Lundberg of Karolinska Hospital,
Sweden, and Dr S. Dobson and Mr P. Howe of the Institute of
Terrestrial Ecology, Monks Wood Experimental Station, United Kingdom.
The second draft was prepared by Dr P. Lundberg incorporating comments
received following the circulation of the first draft to the IPCS
Contact Points for Environmental Health Criteria monographs.
Particularly valuable comments on the draft were made by the European
Chemical Industry Ecology and Toxicology Centre (ECETOC), the
International Agency for Research on Cancer (IARC), the Toxicology
Division, Exxon Biomedical Sciences, and the Conseil European des
Federations de L'industrie Chimique (CEFIC).
Dr B.-H. Chen and Dr P.G. Jenkins, both members of the IPCS Central
Unit, were responsible for the overall scientific content and
technical editing, respectively.
The efforts of all who helped in the preparation and finalization
of the document are gratefully acknowledged.
* * *
Financial support for this Task Group was provided by the United
Kingdom Department of Health as part of its contributions to the IPCS.
ABBREVIATIONS
DEHP diethylhexyl phthalate
DBP di- n-butyl phthalate
DiBP di-iso-butyl phthalate
ECETOC European Chemical Industry Ecology and Toxicology
Centre
ECMO extracorporeal membrane oxidation
HPLC high-performance liquid chromatography
MEHP monoethylhexyl phthalate
NDMA N-dimethylnitrosamine
NOEL no-observed-effect level
PVC polyvinyl chloride
SHE Syrian hamster embryo
SPF specific pathogen free
UDS unscheduled DNA synthesis
US ATSDR US Agency for Toxic Substances and Disease Registry
US FDA US Food and Drug Administration
1. SUMMARY
1.1 Identity, physical and chemical properties, and analytical
methods
Di(2-ethylhexyl)phthalate (DEHP) is a benzenedicarboxylic acid
ester which at room temperature is a colourless to yellow oily liquid.
Its solubility in water is low (0.3-0.4 mg/litre), and is even lower
in salt water. It is miscible with most common organic solvents. The
volatility of DEHP is relatively low (8.6 x 10-4 Pa).
Many sampling and analytical methods have been developed for the
determination of DEHP in different media. Sensitive methods, such as
gas chromatography, high-performance liquid chromatography, and mass
spectrometry are being used increasingly. Analysis of low
concentrations of DEHP is complicated by contamination from plastic
equipment during sampling and analysis.
1.2 Sources of human and environmental exposure
Almost all the DEHP present in the environment arises from
anthropogenic sources rather than from natural ones.
The worldwide production of DEHP has been increasing during
recent decades and at present amounts to about 1 x 106 tonnes per
year. One third of the total production is in the USA and one third in
Europe.
DEHP is the most widely used plasticizer (comprising 50% of all
phthalate ester plasticizers) that softens resins. It may account for
40% (w/w) or more of the plastic. DEHP is used for making the
polyvinyl chloride (PVC) utilized in building, construction and
packaging, and for medical device components. Smaller amounts are used
in industrial paints and as a dielectric fluid in condensers.
Discarded plasticized products may be disposed of either by
incineration or via dumping in a landfill site. During incineration at
a low temperature, a large percentage of the DEHP may be lost to the
atmosphere. The environmental fate of DEHP in landfill sites has not
been well studied and no definite conclusions can be reached.
1.3 Environmental transport, distribution, and transformation
Transport in the air is the major route by which phthalates enter
the environment. From the atmosphere DEHP either falls or is washed
out via rainfall.
DEHP has a high octanol-water partition coefficient, so the
equilibrium between water and an organic-rich soil or sediment is in
favour of the soil or sediment. It is readily adsorbed by organic soil
particles.
Although the solubility of DEHP in water is low, the amount
present in surface water may be higher due to adsorption onto organic
particles and interaction with dissolved organic matter. It is
adsorbed particularly by small particles, and adsorption is enhanced
in salt water.
Atmospheric photodegradation of DEHP is rapid, but its chemical
hydrolysis in the environment is practically non-existent.
Aerobic degradation has been found to be carried out by several
soil microorganisms. However, the microbial degradation of DEHP in the
environment has been reported to be slow. The biodegradation pathway
begins with hydrolysis to the mono-ester, which is then converted to
phthalic acid. The ring-opening degradation to pyruvate and succinate
and then to CO2 and H2O is similar to the metabolic pathway of
benzoic acid. The aerobic degradation is temperature dependent. Below
10 °C little degradation takes place. At higher temperatures
biodegradation proceeds in the upper layer of the soil, but it is
virtually non-existent deeper down where conditions are anaerobic.
Anaerobic degradation, if it exists, is very much slower than aerobic
degradation.
DEHP is highly lipophilic and moderately persistent. The degree
of bioaccumulation depends on the capability of an organism to
metabolize DEHP. It has been shown to accumulate to a high degree in
a variety of aquatic invertebrates, fish, and amphibians.
When DEHP was applied to plant leaves, there was little loss over
a 15-day period. Uptake by plants from soil or sewage sludge was found
to be low.
1.4 Environmental levels and human exposure
DEHP exists widely in the environment and is found in most
samples, including air, precipitation, water, sediment, soil, and
biota. Levels are generally highest in industrialized areas.
DEHP concentrations of up to 300 ng/m3 have been found in urban
and polluted air. Levels of between 0.5 and 5 ng/m3 have been
reported in the air of oceanic areas, and the rainfall in these areas
contained up to about 200 ng/litre. Precipitation samples from an area
close to a plasticizer production plant indicated that the rate of dry
deposition was 0.7 to 4.7 µg/m2 per day.
In rivers and lakes the concentration of DEHP has been found to
be up to 4 µg/litre, highest levels being associated with industrial
effluent discharge points. The concentration in the sea is less than
1 µg/litre, highest levels being in estuaries.
Due to its hydrophobic character, DEHP is readily absorbed to
soil, sediment, and particulate matter. River sediment levels of up to
70 mg/kg (dry weight) have been reported, and these have reached 1480
mg/kg (dry weight) near discharge points.
The concentration of DEHP in biota varies from less than 1 to
7000 µg/kg. It has been found in various types of food, such as fish,
shellfish, eggs, and cheese. The estimated average exposure was around
300 µg/person per day in the USA in 1974 and 20 µg/person per day in
the United Kingdom in 1986.
Blood transfusions and other medical treatment using plastic
devices may lead to involuntary human exposure to DEHP. Levels from
13.4 to 91.5 mg/kg (dry weight) in lung tissue have been detected in
patients.
The few data available indicate that workplace concentrations of
DEHP are usually below 1 mg/m3.
1.5 Kinetics and metabolism
Available data on oral administration indicate that DEHP is
hydrolysed in the gut by pancreatic lipase. The metabolites formed,
i.e. mono(2-ethylhexyl)phthalate (MEHP) and 2-ethyl-hexanol, are
rapidly absorbed. When 14C-labelled DEHP (2.9 mg/kg) was given
orally to rats, more than 50% was recovered in the urine or bile. The
bioavailability of an oral dose of DEHP seems to be higher in young
rats than in older ones.
When administered orally, DEHP is extensively hydrolysed in the
gut in certain animals, e.g., rats, and is mainly distributed as
monoethylhexyl phthalate (MEHP). However, hydrolysis occurs to a much
lesser extent in primates and humans. MEHP binds to plasma proteins.
The liver seems to be the major organ for the metabolism of MEHP and
2-ethylhexanol. Several further metabolites have been identified,
omega- and omega-1-oxidation being the major metabolic pathways. One
or several of the products of omega-oxidation may be further
metabolized by ß-oxidation. Non-linear kinetics have been observed for
the omega-oxidation. DEHP metabolism shows considerable species
differences; e.g., the omega-oxidation pathway is less extensive in
humans than in rats.
Almost 100% of an oral dose of DEHP (2.9 mg/kg) was recovered in
rat faeces and urine after a week. Bile and urine are the major
excretory pathways. In a human study, 15-25% of an oral dose
(0.45 mg/kg) of DEHP was excreted as MEHP, and oxidized metabolites
constituted a major portion of the excretion products.
1.6 Effects on laboratory mammals and in vitro test systems
The oral LD50 for DEHP is about 25-34 g/kg, depending on the
species, but the value for MEHP is lower. In feeding studies on rats
and mice, DEHP dosages greater than 3 g/kg per day caused deaths
within 90 days, and a level of 0.4 g/kg per day reduced weight gain
within a few days. In other studies, 6.3-12.5 g/kg diet caused a body
weight reduction.
Hepatomegaly and increased relative kidney weights have been
observed in treated animals in long-term studies. In one study, there
were also hypertrophic cells in the anterior pituitary.
Several studies have shown testicular atrophy, evident within a
few days, related to DEHP administration (dietary levels of 10-20 g
DEHP/kg). Younger rats seem to be more susceptible than older ones,
and rats and mice seem to be more sensitive than marmosets and
hamsters. Reversibility of the atrophy has been observed. MEHP has
toxic effects on Sertoli cells in vitro. DEHP, as well as MEHP,
shows teratogenic properties. Malformations were observed at dietary
levels of 0.5-2 g/kg in mice, and embryotoxic effects were observed at
dietary levels greater than 10 g/kg.
Tests for mutagenicity and related end-points have been negative
in most studies. DEHP may induce cellular transformation, and it has
been shown to be carcinogenic at doses of 6 and 12 g DEHP/kg diet in
rats and 3 and 6 g/kg diet in mice. There was a dose-related increase
in hepatocellular tumours in both sexes of both species. The induction
of hepatic peroxisome proliferation and cell replication is strongly
associated with the liver carci-nogenic effect of certain non-
genotoxic carcinogens including DEHP. However, marked differences have
been observed among animal species with respect to DEHP-induced
peroxisome proliferation.
In contrast to rat hepatocytes, DEHP metabolites do not produce
peroxisome proliferation in cultured human hepatocytes.
1.7 Effects on humans
Only very limited information is available on the effects of DEHP
on humans. Mild gastric disturbances, but no other deleterious
effects, were reported for two subjects given 5 or 10 g DEHP.
1.8 Effects on other organisms in the laboratory and field
Most studies have yielded nominal LC50 values in acute toxicity
tests that are in excess of 10 mg/litre, values which give a low
toxicity rating for DEHP. However, these levels exceed the DEHP water
solubility (0.3-0.4 mg/litre). One study suggested greater sensitivity
of the water flea Daphnia pulex, with a nominal 48-h LC50 of 0.133
mg/litre. The only acute test with measured DEHP concentrations was on
the fathead minnow and revealed a 96-h LC50 of > 0.33 mg/litre. In
prolonged studies, the no-observed-effect level (NOEL) for Daphnia
magna was 72 µg/litre. For adult fish a NOEL of > 62 µg/litre was
determined. An exposure of 14 µg/litre, from 12 days prior to
hatching, caused a significant increase in trout fry mortality. DEHP
concentrations of between 3.7 and 11 µg/litre led to a reduction in
the vertebral collagen of fish.
The survival of zebra fish fry is adversely affected by DEHP
concentrations of 50 mg/kg food. Sediment concentrations of 25 mg/kg
(w/w) significantly reduced microbial activity and the number of
tadpoles hatching.
The acute toxicity of DEHP to algae, plants, earthworms, and
birds is low.
1.9 Evaluation
DEHP causes reproductive and hepatocarcinogenic effects in rats
and mice.
Testicular atrophy is the main reproductive effect in rats and
mice, and young animals are more susceptible than older ones to this
effect. The induction of hepatic peroxisome proliferation and cell
replication are strongly associated with the liver carcinogenic effect
of certain non-genotoxic carcinogens including DEHP. However, marked
differences have been observed among animal species with respect to
DEHP-induced peroxisome proliferation. Currently there is not
sufficient evidence to suggest that DEHP is a potential human
carcinogen.
There is no documented information that DEHP presents any hazard,
based on acute exposure to fish and daphnids. However, a reduction of
microbial activity in sediment at environmental levels of DEHP was
reported. A comparison between environmental levels and the
concentrations that produce effects in prolonged studies, especially
early life-stage tests on fish and amphibians, indicates that a hazard
for the environment, particularly via water and sediment, cannot be
excluded. Adverse effects on organisms are likely in areas with highly
contaminated water and sediments which are near to point emission
sources.
Although few relevant studies have been reported, the acute
toxicity of DEHP to algae, plants, earthworms, and birds appears to be
low.
2. IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, AND ANALYTICAL
METHODS
2.1 Identity
Common name: di(2-ethylhexyl) phthalate
Structural formula: 
Empirical formula: C24H38O4
Abbreviation: DEHP
Relative molecular
mass: 390.57
Common synonyms:
1,2-benzenedicarboxylic acid bis(2-ethylhexyl) ester (CAS name);
phthalic acid bis(2-ethylhexyl) ester (IUPAC name); BEHP;
1,2-benzenedicarboxylic acid bis(ethylhexyl) ester;
bis(2-ethylhexyl) 1,2-benzenedicarboxylate; bis(2-ethyl-hexyl)
ester of phthalic acid; bis(2-ethylhexyl) phthalate;
di(2-ethylhexyl) ortho-phthalate; di(ethylhexyl) phthalate;
dioctyl phthalate; DOP; ethylhexyl phthalate; 2-ethylhexyl
phthalate; octyl phthalate; di- sec-octyl phthalate; phthalic
acid dioctyl ester
Common trade names:
Bisoflex 81; Bisoflex DOP; Compound 889; DAF 68; Ergoplast FDO;
Eviplast 80; Eviplast 81; Fleximel; Flexol DOP; Goodrite GP 264;
Hatcol DOP; Kodaflex DOP; Mollan O; Nuoplaz DOP; Octoil;
Palatinol AH; Platinol DOP; Pittsburgh; PX-138; Reomol DOP;
Reomol D 79P; Sicol 150; Staflex DOP; Truflex DOP; Vestinol AH;
Vinicizer 80; Witcizer 312 (IARC, 1982; NIOSH, 1985b)
CAS registry
number: 117-81-7
RTECS number: TI 035000
Di(2-ethylhexyl) phthalate (DEHP) is available in a variety of
technical grades. In the USA typical product specifications are:
minimal ester content, 99.0-99.6%; maximal moisture content, 0.1%;
acidity (as acetic acid or phthalic acid), 0.007-0.01%; specific
gravity, 0.980-0.985 (25 °C/25 °C); refractive index, 1.4850-1.4870
(23 °C); and minimal flash-point, 216 °C (IARC, 1982).
In western Europe, DEHP is available with the following
specifications: maximal acid value, 0.06; maximal weight loss on
heating at 140 °C for 3 h, 1%; and saponification value, 284-290 mg
KOH/g (IARC, 1982).
In Japan, DEHP must fulfill the following specifications: maximal
acid value, 0.05; maximal weight loss on heating at 125 °C for 3 h,
0.1%; and specific gravity, 0.983-0.989 (20 °C/20 °C) (IARC, 1982).
2.2 Physical and chemical properties
DEHP is a colourless to yellow, oily liquid at room temperature
and normal atmospheric pressure. The melting point is -46 °C (pour
point) and the boiling point is 370 °C (at atmospheric pressure, 101.3
kPa; 236 °C at 1.33 kPa, and 231 °C at 0.67 kPa). The flash point is
425 °C (open cup) (Clayton & Clayton, 1981; IARC, 1982; SAX, 1984). At
20 °C, the density is 0.98 g/ml (Fishbein & Albro, 1972) and the
vapour pressure 8.6 x 10-4 Pa (Howard et. al., 1985). The log n-
octanol-water partition coefficient is 3-5.
The solubility of uncolloidal DEHP in water is low (45 µg/litre
at 20 °C) (Leyder & Boulanger, 1983). However, DEHP may form colloidal
dispersions which lead to higher values for solubility (Klöpfer et
al., 1982). Values of 285 µg/litre (Hollifield, 1979), 340 µg/litre
(Howard et al., 1985), and 360 µg/litre (Defoe et al., 1990) have been
determined at 20-25 °C. These higher values are probably more
realistic in the environment. Howard et al. (1985) determined a value
of 160 µg/litre at 25 °C in salt water.
DEHP is miscible with most common organic solvents and is more
soluble in blood than water. It is lipophilic and the distribution
ratio in dichloromethane-Krebs bicarbonate buffer has been measured to
be 1130 (Krauskopf, 1973; Clayton & Clayton, 1981; IARC, 1982; Sax,
1984; Weast et al., 1984; Sittig, 1985).
2.3 Conversion factors
1 ppm = 15.87 mg/m3
1 mg/m3 = 0.063 ppm
2.4 Analytical methods
Methods used for the analysis of di(2-ethylhexyl) phthalate in
many types of samples are summarized in Table 1.
Analysis of samples with low concentrations of DEHP is
complicated by the risk of contamination from plastic equipment.
Table 1. Methods for the analysis of di(2-ethylhexyl) phthalate
Sample Sample Assay Limit of
matrix preparation procedure detection Reference
Air collect on cellulose GC/FID range: NIOSH (1977)
ester membrane filter; 2.03-10.9 NIOSH (1985a)
extract disulfide) mg/m3 for
a 32-litre
sample at
23 °C
Air collect with impinger GC/ECD not given Thomas (1973)
(ethylene glycol); GC/MS
extract (hexane)
Marine air trap on glass-fibre filters GC/ECD 0.5 ng/m3 Giam et al.
with foam plugs; Soxhlet (1980)
extract (petroleum ether);
concentrate extracts; clean-up
on deactivated Florisil
columns
Air-borne Soxhlet extract (methanol); GC/MS not given Karasek et al.
particulate concentrate; centrifuge (1978)
matter
River water extract (hexane); filter HPLC/UV 2 ng at Mori (1976)
(normal and 224 nm
reversed-phase
adsorption
chromatography
and gel
chromatography
Table 1 (contd).
Sample Sample Assay Limit of
matrix preparation procedure detection Reference
River water extract (chloroform); thin-layer 50 µg/litre Kataeva (1988)
concentrate extract; dry by chromatography
sodium sulfate treatment;
evaporate; dissolve residue
(chloroform)
Industrial add hydrochloride acid; GC/MC (EI not given Sheldon &
and municipal extract (dichloromethane); and CI modes); Hites (1979)
waste water clean-up by liquid with SIM
chromatographic fractionation
River freeze-dry; homogenize; HPLC/UV 10 ng Schwartz et al.
sediment extract (hexane; acetone; (233 nm) (1979)
methanol); evaporate;
dissolve (hexane); filter
Human serum centrifuge; extract (chloroform: GC/FID 50 µg/litre Lewis et al.
methanol); evaporate; dissolve GC/MS (1977)
(ethyl acetate); treat with
alumina; decant; rinse;
filter; evaporate; dissolve
residue (hexane-containing
butyl benzyl phthalate as an
internal standard)
Human plasma separation on Celite 545; GC/FID 50 ng Piechocki &
extract (diethyl ether); Purdy (1973)
evaporate; dissolve (carbon
disulfide)
Table 1 (contd).
Sample Sample Assay Limit of
matrix preparation procedure detection Reference
Stored blood; lyophilize; suspend; filter; GC/FID not given Contreras et
whole blood wash residue; mix with distilled al. (1974)
water; centrifuge; add silicic
acid to chloroform phase;
mix; centrifuge; decant;
evaporate; dissolve; centrifuge
Human and grind wet tissue samples GC/FID 0.3 µg/g Chen et al.
animal in saline; extract homogenate (wet tissue) (1979b)
tissue and or urine; dilute with 15 ng/ml Chen et al.
urine chloroform:methanol (urine) (1979a)
Intravenous add hydrochloric acid; GC/ECD 4 µg/litre Arbin &
solutions extract (dichloromethane); Östelius
redissolve (1980)
Organic evaporate; dissolve GC/FID not given Ishida et al.
solvents (diethyl ether) (1980)
Solid immerse in chloroform: GC/FID not given Ishida et al.
reagents methanol; filter; rinse; (1980)
evaporate
Aluminium cut into small pieces; GC/FID not given Ishida et al.
foil; rubber immerse in chloroform: (1980)
tubing, etc. methanol; extract
Abbreviations: GC = gas chromatography; FID = flame-ionization detection; ECD =
electron capture detection; MS = mass spectrometry; HPLC = high-
performance liquid chromatography; UV = ultraviolet spectroscopy;
EI = electron impact; CI = chemical ionization; SIM = selected ion
monitoring.
3. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE
It seems likely that by far the major part of the phthalate
esters present in the environment arises from human activity and not
from natural sources. Some dialkyl esters may be found in coals, crude
oil, and shales while others may have plant origins, but most
originate either directly or indirectly from industrial processes.
Phthalic acid has been reported to be formed during the bacterial
metabolism of phenanthrene.
3.1 Natural occurrence
Phthalates have been reported in a wide variety of substances
(oil, soil, plants, and animals) and over a wide geographical area.
Most occurrences have anthropogenic origins but some could be of
natural origin. The nature of the origin is further complicated by the
fact that sampling techniques often lead to contamination of samples
via contamination from plastic bags or bottles. Mathur (1974a)
critically reviewed this question and concluded that the possibility
of the phthalic acid esters found in biological and geochemical
samples being of biosynthetic origin cannot be ruled out. Both Mathur
(1974a) and Peakall (1975) cite reports where phthalates were detected
yet no anthropogenic source could be found. Studies by Manandhar et
al. (1979) and Pare et al. (1981) also revealed residues of phthalates
in biological samples where the source seemed to be natural. Peterson
& Freeman (1984) suggested that some of the phthalates found in older
samples (from the 1920s and 1930s) of sediment cores from Chesapeake
bay, USA, may have been of natural origin.
An ECETOC (European Chemical Industry Ecology and Toxicology
Centre) task force concluded that, although knowledge of naturally
produced phthalates is limited or uncertain, it is unlikely that this
contribution is of significance except, possibly, in very localized
areas (ECETOC, 1985).
3.2 Anthropogenic sources
3.2.1 Production levels
About 2.7 x 106 tonnes of total phthalates are produced
annually, of which the non-plasticizer (dimethyl and diethyl)
phthalates represent a very small fraction. Of the plasticizer
phthalates, DEHP accounts for well over 50% of the tonnage, the
contribution of the remaining compounds ranging from about 1% to 10%
each (ECETOC, 1985).
The production of DEHP has been increasing since it was first
used commercially in 1949. During the period 1950-1954, the production
in the USA was 106 x 103 tonnes, and by the period 1965-1969 the
level had risen to 650 x 103 tonnes (Peakall, 1975).
The estimated world consumption of DEHP in 1984 was 1.09 x 106
tonnes (SRI, 1985).
3.2.2 Uses
Phthalate acid esters are the most widely used plasticizers for
the production of polyvinyl chloride (PVC) products (with DEHP as the
plasticizer). Phthalates are used for the insulation of wires and
cables, in floor tiles, weatherstripping, upholstery, garden hose,
swimming pool liners, footwear and clothing. They are also used in
food wrapping and containers, although in some countries this use is
prohibited by law. They also have non-plasticizer uses, e.g., as
pesticide carriers.
DEHP has been widely used since 1949. An important property is
that it softens resins without reacting with them chemically. This has
led to about 95% of DEHP production being directed towards plasticizer
use, particularly in PVC products such as tubing and medical device
components. It is also used as a plasticizer in cellulose ester
plastics and synthetic elastomers. The DEHP content of these products
generally ranges from 20 to 40%, but for some uses it is up to 55%.
The most important non-plasticizer use of DEHP is as a dielectric
fluid in capacitors.
3.2.3 Disposal of plasticized products
Most discarded plasticized products are disposed of either by
incineration or via dumping in a tip/landfill site. When incinerated
at high temperature the combustion of phthalates is nearly complete.
However, if combustion is uncontrolled and occurs at a low
temperature, a large percentage of the phthalates may be lost to the
atmosphere. After dumping in a landfill site, phthalates may leach
into the aquatic environment, but because of their high affinity for
organic soil particles and their low water solubility this is not
likely to be a major route into the environment. Indiscriminate
dumping is more likely to lead to volatilization of phthalates to the
atmosphere rather than leaching to the aquatic environment (ECETOC,
1985).
4. ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION
4.1 Environmental transport and distribution
The release of phthalates to the environment may occur as
follows:
a) during production and distribution;
b) during the manufacture of plasticized products;
c) during the use of plasticized product;
d) after disposal.
It was concluded by ECETOC (1985) that most of the phthalates
entering the environment are likely to do so by volatilization to the
atmosphere, only a minor part (perhaps 10%) entering the aquatic
environment by leaching.
The estimated worldwide emissions of DEHP are given in Table 2.
However, as reported by ECETOC (1985), the loss of DEHP from modern
production plants is negligible.
4.1.1 Transport in air
ECETOC (1985) suggested that transport in air is the major route
by which phthalates enter the environment. DEHP is volatilised to the
atmosphere and then either falls as dry deposition or is "washed out"
via rainfall.
DEHP has been measured in air samples from remote sites at
Enewetak Atoll in the North Pacific Ocean (Atlas & Giam, 1981), the
North Atlantic (Giam et al., 1978), the Gulf of Mexico (Giam et al.,
1978, 1980), and Sweden (Thurén & Larsson, 1990).
4.1.2 Transport in soil and sediment
DEHP has a high n-octanol-water partition coefficient, so the
equilibrium between water and an organic-rich soil or sediment will be
very much in favour of the soil or sediment. Absorbance of DEHP by
soil or sediment is also enhanced by van de Waals type bonding with
natural soil minerals, promoted by the presence of benzene rings and
carbonyl groups, and also by the low solubility of DEHP (ECETOC,
1985).
From results with other organic substances, Wams (1987) estimated
that 90% of DEHP is readily adsorbed by organic soil particles.
As can be seen from section 5.1.4, the sediment or hydrosoil
tends to act as a sink for DEHP.
Table 2. Estimated worldwide emission of DEHP, based on an estimated
total annual production of 4 x 106 tonnesa
Phase Emission (tonnes/year) Route
Production up to 40 000 waste water
Distribution 2000 sewage systems
Production of PVC 32 000 air and water
During use of plastics 14 000 air
6000 water
After disposal:
to landfill sites up to 200 000 percolating water
to waste incinerators ? air
uncontrolled burning ? air
a Adapted from Wams (1987). The values are higher than those from
other sources (ECETOC, 1985)
4.1.3 Transport in water
The solubility of DEHP in water is low (0.3 mg/litre at 25 °C).
However, the amount present in surface water may be higher than the
actual solubility as a result of adsorption onto organic particles
(Taylor et al., 1981) and interactions with dissolved organic matter
of high relative molecular mass, such as humic and fulvic acid
(Matsuda & Schnitzer, 1971).
DEHP has been found to adsorb to suspended particulate matter
fairly rapidly, in less than 2 to 3 h, especially to small particles
(Al-Omran & Preston, 1987). This adsorption was more rapid in salt
water than in fresh water. Taylor et al. (1981) reported that between
one-half and two-thirds of the DEHP in Mississippi River water is
associated with particulate matter.
By extrapolating laboratory data on the volatilization of DEHP
from water under defined conditions, Klopffer et al. (1982) obtained
a half-life in water of 146 days, although on purely theoretical
grounds a value of only 25 days was calculated.
Using the Exposure Analysis Modeling System (EXAMS), Wolfe et al.
(1980a) calculated that at equilibrium the loss of DEHP via
volatilization from a model river, a pond, an eutrophic lake, and an
oligotrophic lake would be 0%, 2.8%, 2.2% and 2.3%, respectively.
4.1.4 Transport between media
Eisenreich et al. (1981) estimated that the total annual
deposition of DEHP from air into the Great Lakes, North America,
varied from 3.7 tonnes (Lake Ontario) to 16 tonnes (Lake Superior).
DEHP has a high n-octanol/water partition coefficient. This
means that biota living in phthalate-containing water would be
expected to have a higher phthalate level than the water itself (see
section 4.2.3). However, many organisms are able to metabolize DEHP,
and the concentrations found may be lower than those expected on the
sole basis of partition coefficient.
During the 33-day period of a model ecosystem study, the
concentration of 14C in the aquatic phase reached a peak of 31
µg/litre at the fifth day after treatment and had declined to 7.7
µg/litre by the end of the experiment. This decline was stated to be
the result of the uptake of DEHP and its degradation products by the
organisms in the model ecosystem (Metcalf et al., 1973).
Lokke & Bro-Rasmussen (1981) treated the leaves of Sinapsis alba
with a mixture of di-iso-butyl phthalate (DiBP), di- n-butyl
phthalate (DBP), and DEHP at a rate of 2.5 µg/cm2. Only very small
amounts of DEHP evaporated from the leaves during the 15-day
experiment, compared with DiBP (71%) and DBP (43%).
4.2 Biotransformation
4.2.1 Abiotic degradation
As a result of atmospheric photodegradation, the atmospheric
half-life of DEHP is less than one day (ECETOC, 1985).
Chemical hydrolysis of DEHP is practically non-existent, the
half-life being > 100 years in water at pH 8 and 30 °C (Wolfe et al.,
1980b).
4.2.2 Biodegradation
Aerobic degradation has been found from several micro-organisms
in soil, sludge, sediment, and water. Anaerobic degradation is very
much slower, or possibly even non-existent.
The first step in the metabolic pathway for the biodegradation of
DEHP is the hydrolysis of the diester to the monoester by esterases
with low substrate specificity (Kurane et al., 1980; Taylor et al.,
1981). The monoester is then converted into phthalic acid (Engelhardt
et al., 1975). The ring-opening degradation to pyruvate and succinate
and then to CO2 and H2O is similar to the metabolism of benzoic
acid. According to Kurane et al. (1984), this is probably why the
biodegradation of phthalic esters is so widespread. It appears that
mixed populations of microorganisms are the most successful at
completely degrading DEHP (Engelhardt et al., 1975; Kurane et al.,
1979). When pure cultures of bacteria, selectively isolated in the
laboratory, are used for the biodegra-dation of phthalates,
accumulation of the breakdown products tends to occur (Keyser et al.,
1976).
4.2.2.1 Aerobic degradation
Aerobic degradation of DEHP has been found with several
microorganisms, including bacteria and fungi. Overall, it appears that
phthalates with short alkyl chains undergo rapid degradation, whereas
those with longer chains, such as DEHP, are only 40-90% degraded after
10-35 days (ECETOC, 1985).
Graham (1973) reported that laboratory-scale activated sludge
processes degraded 91% of introduced DEHP within 38 h. Saeger & Tucker
(1973) demonstrated that all phthalates tested underwent complete
aerobic degradation in activated sludge and river water.
Aerobic degradation of DEHP depends on temperature. Mathur
(1974b) incubated a loam soil with DEHP at 4, 10, 22-25, and 32 °C,
and soil respiration rates were measured after 14 weeks. Increased
rates of respiration, showing that microbial degradation was taking
place, were found at all temperatures. However, at 4 and 10 °C results
indicated that only marginal degradation was taking place.
Johnson & Lulves (1975) incubated freshwater hydrosoil containing
14C-DEHP (1 mg/litre) under aerobic conditions, and after 14 days,
50% of the DEHP had been degraded. This was a much slower rate of
degradation than that found with DBP, where 98% was degraded within 5
days. Johnson et al. (1984) studied the biodegradation of phthalic
acid esters in freshwater sediment and found that the length and
configuration of the alkyl phthalate diester significantly affected
the primary biodegradation rate. After a 14-day incubation in aerobic
sediment at 22 °C, less than 2% of the branched-chain alkyl phthalate
DEHP had been degraded whereas over the same period the linear alkyl
DBP showed 85% degradation. DEHP degradation was significantly greater
at very high concentrations (10 mg/litre) and at temperatures above 22
°C. Neither inorganic nitrogen nor phosphorus influenced the
degradation of DEHP. Engelhardt et al. (1977) found that the fungus
Penicillium lilacinum degraded approximately half of the initial
amount of DEHP within 30 days, yielding the corresponding monoester,
a second metabolite, which is hydroxylated in the alcohol moiety, and
at least four minor metabolites. The bacterium Pseudomonas
acidovorans completely degraded DEHP at a medium concentration of
5000 mg/kg within 72 h (Kurane et al., 1977).
Saeger & Tucker (1976) found that 60% of the DEHP had undergone
primary biodegradation within 5 weeks in Mississippi River water.
Rapid primary degradation was found when DEHP was added to activated
sludge at the rate of 5 mg/24 h. Depending on the source of the
sludge, between 70% and 78% was degraded. To monitor whether complete
biodegradation was being achieved, the authors measured CO2
evolution. Within the 14 days of incubation DEHP had essentially been
completely degraded to CO2 and water under the conditions of this
test. Taylor et al. (1981) showed the presence of significant
populations of taxonomically distinct bacteria that grew on a range of
phthalic acid esters, including DEHP, in the water and sediments of
the Mississippi River region.
Sugatt et al. (1984) used an acclimated shake-flask
CO2-evolution test to study the biodegradation of DEHP and reported
an initial breakdown of the parent compound of > 99% within the 28
days. The authors calculated a half-life of 5.25 days for the primary
biodegradation of DEHP.
In surface waters, DEHP is strongly adsorbed to organic particles
(Taylor et al., 1981), which tends to reduce degradation (Baughman et
al., 1980).
In the upper layer of soil, biodegradation of phthalates proceeds
as in surface water, but deeper down, where conditions are anaerobic,
it is virtually nonexistent (Engelhardt & Wallnofer, 1978). Shanker et
al. (1985) incubated garden soil containing DEHP at a concentration of
500 mg/kg. Within 20 days, 75% of the DEHP had been degraded and,
after 30 days, more than 90%. Again the rate of degradation was much
slower than that found for either di- n-methyl or di- n-butyl
phthalate. No degradation was detectable when sterilized soil was
used.
4.2.2.2 Anaerobic degradation
Johnson & Lulves (1975) found DEHP to be completely resistant to
microbial attack under anaerobic conditions. After 30 days, there was
no significant loss of 14C-DEHP activity in freshwater hydrosoils
overlaid with nitrogen.
Shanker et al. (1985) reported that degradation of DEHP was much
slower in anaerobic soil, flooded with sterile water to reduce the
oxygen tension. After a 30-day incubation, 33% of the DEHP had been
degraded, compared with more than 90% in the case of aerobic soil.
O'Connor et al. (1989) studied the biodegradation of DEHP under
anaerobic conditions in a medium containing municipal digester sludge
over a period of 140 days. DEHP, which was the only carbon source, was
added at a rate of 20, 100, and 200 mg/litre, and 100%, 69%, and 54%
of the DEHP was degraded at the three respective concentrations.
However, complete biodegradation to carbon dioxide and methane was
minimal.
Ziogou et al. (1989) studied the behaviour of DEHP (0.5, 1, and
10 mg/litre) during batch anaerobic digestion of sludge over a 32-day
period. No degradation of DEHP was observed during this period.
4.2.3 Bioaccumulation
DEHP is highly lipophilic, the log n-octanol-water partition
coefficient being 3 to 5, and it is moderately persistent. The
accumulation of DEHP is also influenced by the capability of an
organism to metabolize it. Melancon (1979) reviewed the metabolism of
phthalates in aquatic organisms. Bioconcentration factors for DEHP in
a variety of aquatic organisms are given in Table 3.
Table 3. Bioaccumulation of DEHP in aquatic organisms
Organism Stat/ Exposure Exposure Bioconcentration Reference
flowa period concentration factorc
(µg/litre)
Freshwater organisms
Canadian pondweed stat 24 h 10 274.8d Metcalf et al. (1973)
(Elodea canadensis) stat 12 h 10 000 133.8d Metcalf et al. (1973)
Snail stat 48 h 10 857.5d Metcalf et al. (1973)
( Physa sp) stat 6 h 10 000e 402d Metcalf et al. (1973)
Scud flowb 7 day 0.1 13 600 Sanders et al. (1973)
(Gammarus pseudolimnaeus) flow 7 day 0.1 3900 Mayer & Sanders (1973)
Water flea flowb 7 day 0.3 5200d Sanders et al. (1973)
(Daphnia magna) flow 7 day 0.3 420 Mayer & Sanders (1973)
stat 1 h 10 421d Metcalf et al. (1973)
stat 12 h 10 000e 133.8d Metcalf et al. (1973)
Sowbug flowb 21 day 62.3 250d Sanders et al. (1973)
(Asellus brevicaudus)
Mosquito (larvae) stat 12 h 10 1320.2d Metcalf et al. (1973)
(Culex pipiens stat 24 h 10 000e 1187.3d Metcalf et al. (1973)
quinquefasciatus) stat 24 h 10 20.3d Metcalf et al. (1973)
stat 48 h 10 000e 434.6d Metcalf et al. (1973)
Midge larvae (3rd instar) flowb 7 day 0.2 408 Streufert et al. (1980)
(Chironomus plumosus) flowb 7 day 0.3 3100d Sanders et al. (1973)
flow 7 day 0.3 350d Mayer & Sanders (1973)
Mayfly flowb 7 day 0.1 2300d Sanders et al. (1973)
(Hexagenia bilineata) flow 7 day 0.1 575d Mayer & Sanders (1973)
Table 3 (contd).
Organism Stat/ Exposure Exposure Bioconcentration Reference
flowa period concentration factorc
(µg/litre)
Mosquito fish stat 48 h 100 265.3d Metcalf et al. (1973)
(Gambusia affinis) stat 12 h 10 000e 129.4d Metcalf et al. (1973)
Fathead minnow flow 14 day 1.9 458d Mayer & Sanders (1973)
(Pimephales promelas) flow 56 day 1.9 886d Mehrle & Mayer (1976)
Marine organisms
Eastern oyster (muscle) stat 24 h 100 11.2 Wofford et al. (1981)
(Crassostrea virginica) stat 24 h 500 6.9 Wofford et al. (1981)
Brown shrimp stat 24 h 100 10.2 Wofford et al. (1981)
(Penaeus aztecus) stat 24 h 500 16.6 Wofford et al. (1981)
Sheepshead minnow stat 24 h 100 10.7 Wofford et al. (1981)
(Cyprinodon variegatus) stat 24 h 500 13.5 Wofford et al. (1981)
a Stat = static conditions (water unchanged for the duration of the test); flow = flow-through conditions
(DEHP concentration in water continuously maintained, unless stated otherwise)
b Intermittent flow-through conditions
c Bioconcentration factor = concentration of DEHP in organism divided by concentration of DEHP in water
d Bioconcentration factor calculated using a radioactive isotope (values represent parent compound plus
radiolabelled products)
e DEHP applied directly to water
4.2.3.1 Model ecosystems
Metcalf et al. (1973) studied the uptake of 14C-labelled DEHP
from water by aquatic organisms in a model ecosystem containing algae
(Oedogonium), snails ( Physa sp.), mosquito larvae (Culex pipiens
quinquefasciatus), and fish ( Gambusia sp). The mosquito larvae
showed the highest concentration factor and the fish the lowest.
Labelled DEHP was added to Sorghum plants and at the end of the 33-
day experiment the water contained 0.34 µg DEHP per litre, the algae
18.32 mg/kg (53 890 x), the snails 7.3 mg/kg (21 480 x), the mosquito
larvae 36.61 mg/kg (10 7670 x), and the fish 0.044 mg/kg (130 x).
Sodergren (1982) exposed fish, aquatic invertebrates, and plants
to 14C-labelled DEHP at a concentration of 1.4 mg/litre for 27 days
under static conditions. After 5 days, 1/50 of the added amount of
DEHP was still present in the water, and at the end of the experiment
62% was recovered from the various surfaces (glass walls, sediment and
surface microlayer). All organisms accumulated DEHP. The amphipod
Gammarus pulex, larvae of trichopterans, and the snail Planorbis
corneus accumulated the DEHP to the highest degree, the
concentration factors ranging from 17 000 to 24 000. The submerged
plants, Mentha aquatica and Chara chara, also showed uptake and
storage of large amounts (concentration factor of 18 000). However,
the fish (stickleback, Pungitius pungitius, and minnow, Phoxinus
phoxinus) did not accumulate 14C-DEHP to any great extent
(concentration factors of 300 or less). Large accumulations of DEHP
occurred in organisms living and/or feeding at interfaces.
4.2.3.2 Aquatic invertebrates
Brown & Thompson (1982a) exposed Daphnia magna to nominal
14C-labelled DEHP concentrations of 3.2, 10, 32, and 100 µg/litre
for 21 days and obtained bioconcentration factors of 166, 140, 261,
and 268 at the four respective concentrations.
When Brown & Thompson (1982b) exposed mussels (Mytilus edulis)
to labelled DEHP at concentrations of 4.1 and 42.1 µg per litre, in
both cases equilibrium was reached within 14 days with a concentration
factor of 2500. Exposure ceased on day 28 but the mussels were
monitored for a further 14 days. The half-life for loss of DEHP over
this period was calculated to be 3.5 days.
Laughlin et al. (1978) exposed grass shrimp, during larval
development, to DEHP concentrations of up to 1 mg/litre for 28 days.
DEHP was not detectable in shrimp tissues at or above a level of 2
mg/kg.
When Streufert et al. (1980) exposed midge larvae (Chironomus
plumosus) to a radioactively labelled DEHP concentration of 0.2
µg/litre, the larvae accumulated DEHP to 292 times the concentration
in water within 2 days. DEHP levels in the midge larvae reached a
plateau after 7 days at a bioconcentration factor of 408. Some of the
larvae were transferred to clean water after 4 days, by which time
they had accumulated 56 µg DEHP/kg, and the half-life for loss was
calculated to be 3.4 days.
After 9 weeks of exposure to sediment containing approximately
600 mg/kg, dragonfly larvae had taken up 14.7 mg DEHP per kg. This was
significantly more than control larvae, which contained 2.9 mg/kg
(Woin & Larsson 1987).
Hobson et al. (1984) fed penaeid shrimps on a diet containing
between 40 and 50 000 mg DEHP/kg for 14 days at a rate of 40 g/kg body
weight per day. Whole body residues ranged from 0.249 to 18.3 mg/kg in
a dose-related manner.
4.2.3.3 Fish
Macek et al. (1979) exposed bluegill sunfish (Lepomis
macrochirus) to 14C-DEHP, both via food at a concentration of 2.8
mg/kg and via water at 5.6 µg/litre, for up to 35 days. The steady-
state body burden of 14C-DEHP after exposure via food and water was
0.73 mg/kg and via water alone was 0.64 mg/kg. The authors concluded
that the uptake of DEHP via the aquatic food chain was statistically
indistinguishable from that due to aqueous exposure. The time required
for the fish to eliminate 50% of the residue burden during depuration
in uncontaminated water was < 3 days.
In a study by Karara & Hayton (1989), sheepshead minnows
(Cyprinodon variegatus) were exposed to a 14C-DEHP concentrations
of 60 ng/litre at temperatures ranging from 10 °C to 35 °C for a
period of between 72 h and 160 h. The amount of DEHP accumulated after
72 h was 6 times greater at 35 °C than at 10 °C, and the
bioconcentration factors increased exponentially with temperature from
45 at 10 °C to 6510 at 35 °C. Metabolic clearance also increased as a
function of temperature, the maximum value being reached at a
temperature of between 29 °C and 35 °C.
Tarr et al. (1990) exposed three sizes (2.9 g, 61 g, and 440 g)
of rainbow trout (Oncorhynchus mykiss) to 14C-DEHP at 20 ng/ml
under static conditions for up to 96 h at 12 °C. The body-weight-
associated changes in the pharmacokinetic parameters caused the
bioconcentration factor to decline from 51.5 to 1.6 as body weight
increased.
When Mehrle & Mayer (1976) exposed rainbow trout (Salmo
gairdneri) eggs (12 days prior to hatching to 24 days post-hatching)
to 14C-labelled DEHP at concentrations of 5, 14, and 54 µg/litre,
the bioconcentration factors were 78, 113, and 42, respectively.
Mayer (1976) exposed fathead minnows (Pimephales promelas) to
DEHP concentrations ranging from 1.9 to 62 µg/litre for 56 days under
flow-through conditions. As the exposure concentration increased,
concentration factors, measured after 56 days, decreased from 569 to
91. Equilibrium was attained after 28 days at the lowest dose and
after 56 days at the highest dose. After exposure the fish were placed
in uncontaminated water for 28 days, and the half-lives for loss
ranged from 6.2 days (at 2.5 µg/litre) to 18.3 days (at 62 µg/litre).
4.2.3.4 Amphibians
Larsson & Thuren (1987) exposed moorfrog eggs to sediment DEHP
concentrations ranging from 10 to 800 mg/kg (fresh weight of
sediment). The eggs hatched after about 3 weeks and the tadpoles were
analysed after 60 days. The DEHP was released from the sediment to the
overlying water, and the losses to the water increased linearly with
increasing levels in the sediment (from 0.89 to 187.4 µg/litre). DEHP
accumulated in the tadpoles at concentrations ranging from 0.28 to
246.8 mg/kg wet weight, and the accumulation increased with increasing
DEHP concentration, both in sediment and water.
4.2.3.5 Plants
Lokke & Bro-Rasmussen (1981) applied DEHP as a mixture that also
contained DiBP and DBP at a concentration of 2.5 µg/cm2 to the
leaves of Sinapis alba. The residue level of DEHP on the leaves
immediately after application was 2.7 µg/cm2. After 15 days, DEHP
levels had decreased to 0.8 µg/cm2, but when the growth of the plant
was taken into account, no significant loss of DEHP over this period
was found. Lokke & Rasmussen (1983) also found little loss of DEHP
over a 15-day period when they applied it (as a mixture with DBP) to
Achillea at a concentration of 3.5 µg/cm2 or to Sinapis at 3.1
µg/cm2. Residues ranged from 120 to 155 µg/plant, and approximately
80% of the DEHP accumulated was on the surface of the leaf.
When Schmitzer et al. (1988) grew barley from seed in soil
containing 1 or 3.33 mg 14C-DEHP/kg dry soil for 7 days, only 0.61%
and 1.25%, respectively, of the applied 14C was taken up by the
plants. Aranda et al. (1989) also found low accumulation of DEHP by
plants grown in sewage sludge containing DEHP. Lettuce (Lactuca
sativa), carrot (Daucus carota), chile pepper (Capiscum annuum),
and tall fescue (Festuca arundinaca) were all grown in sludge
containing 14C-DEHP levels of between 2.57 and 14.07 mg/kg.
Bioconcentration factors ranged from 0.06 to 0.53 (based on initial
soil concentration and plant dry weight).
4.2.3.6 Birds
Belisle et al. (1975) fed mallard ducks (Anas platyrhynchos) on
a diet containing 10 mg DEHP/kg for a period of 5 months. No DEHP was
detected in fat tissue, but 0.1 and 0.15 mg/kg (wet weight) were found
in breast muscle and lung tissue, respectively.
O'Shea & Stafford (1980) exposed starlings (Sturnus vulgaris)
to a dietary DEHP concentration of 25 or 250 mg/kg for 30 days. One
of eight birds fed 25 mg/kg contained detectable residues (1.6 mg/kg)
after 30 days exposure, and five of eight birds fed 250 mg/kg
contained an average of 1.8 mg/kg. The same proportion of birds fed
the higher dose still had detectable residues (an average of 1.3
mg/kg) 14 days after dosing had finished.
When Ishida et al. (1982) fed hens on a diet containing 5 or 10
g/kg for up to 230 days, DEHP was detected in all tissue monitored
except the brain. Residues ranged from non-detectable to 42.5 mg/kg
for most tissues. However, adipose tissue (192.7 to 899.6 mg/kg) and
feathers (513.1 to 1165.2 mg/kg) accumulated the highest
concentrations. A similar pattern of uptake was observed in hens fed
2 g/kg for 25 days, although the amount of DEHP accumulated was much
lower. At this dose level no accumulation had occurred in tissues
other than liver and feather within 5 days.
5. ENVIRONMENTAL LEVELS AND EXPOSURE
5.1 Environmental levels
DEHP exists widely in the environment and is found in most
samples, including air, precipitation, water, sediment, soil, and
biota. Residues have also been detected in food and in humans.
In many cases it is not clear whether the phthalate measured in
samples is naturally occurring or is exogenous. However, there seem to
be clear indications that high levels of DEHP are anthropogenic in
origin.
5.1.1 Air
The levels of DEHP in air have been monitored in the North
Atlantic, the Gulf of Mexico, and on Enewetak Atoll in the North
Pacific and found to range from not detectable to 4.1 ng/m3 (Giam et
al., 1978; Giam et al., 1980; Atlas & Giam 1981). Similar levels
(between 0.5 and 5 ng/m3) have been found in the Great Lakes
ecosystem (Eisenreich et al., 1981) and in the Swedish atmosphere
(Thurén & Larsson, 1990). The DEHP content of these samples was at
least an order of magnitude lower than those found in urban areas such
as New York city, where levels of up to 28.6 ng/m3 have been found
(Bove et al., 1978). Based on the analysis of snow samples, Lokke &
Rasmussen (1983) calculated DEHP concentrations in air of 22 ng/m3
at Lyngby, Denmark. Levels of 29-132 ng/m3 have been found in
Antwerp, Belgium (Cautreels et al., 1977), 126 ng/m3 in polluted air
in Belgium (Cautreels & Van Cauwenberghe, 1978), 300 ng/m3 in
polluted air in Canada (Thomas, 1973), and 38-790 ng/m3 in Japan in
1985 (Environment Agency of Japan, 1989).
5.1.2 Precipitation
Atlas & Giam (1981) measured levels of DEHP in rainfall at
Enewetak Atoll, North Pacific, of 5.3-213 ng/litre (mean, 55
ng/litre). Eisenreich et al. (1981) reported between 4 and 10 ng/litre
in precipitation falling on the Great Lakes ecosystem and Thurén &
Larsson (1990) a level of 55 ng/litre in Sweden. Goto (1979) found a
range of mean rainwater concentrations of 0.65 to 3.16 µg/litre in
various Japanese cities.
Lokke & Rasmussen (1983) analysed snow sampled near a plasticizer
production plant 14 days after a snowfall. Levels of DEHP ranged from
0.7 to 4.7 µg/m2 per day over this period, the highest levels being
within 150 m of the plant and the lowest levels at least 600 m away.
5.1.3 Water
Levels of DEHP found in water are summarized in Table 4.
Table 4. Concentrations of DEHP in water
Location Country Year Concentration Reference
µg/litrea
Marine
Northern Atlantic 0.0001-0.006 Giam et al. (1978)
Gulf of Mexico 0.006-0.316 Giam et al. (1978)
Estuaries Germany ND-0.3 Weber & Ernst (1983)
Nueces Estuary,
Texas USA 1980 0.2-0.77 Ray et al. (1983b)
Estuaries United Kingdom 1981 0.058-0.078 Waldock (1983)
Freshwater
Various rivers Japan ND-3.1 Kodama et al. (1975)
Various cities Japan 1974 0.1-2.19 Goto (1979)
River Meuse Netherlands 1983 < 0.1-3.5 Wams (1987)
River Rhine Netherlands 1983 ND-1.2 Wams (1987)
River Rhine Netherlands 1982 ND-4.0 Wams (1987)
a ND = not detectable
Thuren (1986) analysed water samples from the Rivers Ronnebyan
and Svartan, Sweden, and found DEHP concentrations ranging from 0.32
to 3.1 µg/litre and from 0.39 to 1.98 µg/litre, respectively. The
highest concentrations were associated with industrial effluent
discharge points.
Few samples of ground water have been analysed for DEHP. Wams
(1987) reported that contaminated ground water in the Netherlands
contained between 20 and 45 µg/litre, while Rao et al. (1985) found
DEHP levels of up to 170 µg/litre in New York state ground water.
In a non-industrialised estuary in the United Kingdom, Waldock
(1983) measured DEHP levels of 58 to 78 ng/litre. Ray et al. (1983b)
found levels of DEHP ranging from 210 to 770 ng/litre in a Nueces
estuary in Texas, USA, while Weber & Ernst (1983) found DEHP levels of
up to 300 ng/litre in German estuaries. DEHP levels of up to 316
ng/litre have been found in the Gulf of Mexico, but levels in the
North Atlantic were much lower (Giam et al., 1978). In Japan, river
and marine levels in 1982 ranged from 0.1 to 0.8 µg/litre (Environment
Agency of Japan, 1989).
Ritsema et al. (1989) analysed samples from Lake Yssel,
Netherlands, and found DEHP levels of < 0.1 to 0.3 µg/litre in water
and levels of 12-25 mg/kg in suspended particulate matter. The authors
concluded that the probable source of DEHP was the River Yssel.
Preston & Al-Omran (1986) sampled water and suspended
particulates from the Mersey estuary, United Kingdom, in 1985, and
reported DEHP concentrations ranging from 83 to 335 ng/litre in water
and from 182 to 1700 µg/kg in particulate matter. However, in 1986,
levels were 125-693 ng/litre in water and 280-640 µg/kg in particulate
matter (Preston & Al-Omran, 1989).
5.1.4 Sediment
DEHP levels in sediment are summarized in Table 5.
Being lipophilic DEHP tends to be adsorbed onto sediment, which
acts as a sink. Sediment samples from various Dutch rivers have been
found to contain between 1 and 70 mg/kg (Schwartz et al., 1979; Wams,
1987). Taylor et al. (1981) analysed sediment samples from the
Mississippi River and found similar levels. Sediment levels of DEHP
in the Chester River Maryland, USA, were found to be less than 45
µg/kg dry weight, but, in a tributary of this river, sediment levels
were up to 4.8 mg/kg about 2 km downstream from a phthalate ester
plant outfall. The Chester River flows into Chesapeake Bay, which
contained sediment DEHP levels of 110 µg/kg (Peterson & Freeman 1984).
In Sweden, Thuren (1986) found sediment DEHP levels ranging from 1.2
to 628 mg/kg (dry weight) in the River Ronnebyan and 0.15 to 1480
mg/kg in the River Svarten. As was found with water samples (see
section 5.1.3), in both rivers the highest residues of DEHP were near
to industrial effluent discharge points.
Giam et al. (1978) analysed sediment from the Mississippi delta
and reported mean DEHP levels of 69 µg/kg. Sediment samples from
Nueces Estuary, Texas, USA, unlike the water samples, reflected local
inputs of pollutants. The highest levels (up to 16 mg/kg) were
associated with industrial areas, whereas other areas of the estuary
contained levels ranging from 40 to 330 µg/kg. Much lower levels of
DEHP were found on the Gulf of Mexico coast and in the open sea (mean
levels of 6.6 and 2 µg/kg, respectively) (Giam et al., 1978).
Table 5. Concentrations of DEHP in sediment
Location Country Year Concentration Reference
(µg/kg)a
Gulf of Mexico < 0.1-248 ns Giam et al. (1978)
Nueces Estuary, Texas USA 1980 40-16 000 dw Ray et al. (1983b)
Portland, Maine USA 1980 60-7800 dw Ray et al. (1983a)
Chester River, Maryland USA 1978 20-4800 dw Peterson & Freeman (1984)
River Mississippi USA 1981 140 dw Taylor et al. (1981)
River Meuse Netherlands 1977 1000-17 000 dw Schwartz et al. (1979)
River Ijssel Netherlands 1977 2500-52 500 dw Schwartz et al. (1979)
River Rhine Netherlands 1978 4000-36 000 ns Wams (1987)
River Rhine Netherlands 1977 6500-70 500 dw Schwartz et al. (1979)
Various cities Japan 1974 80-1360 dw Goto (1979)
Crouch Estuary, Essex United Kingdom 1981 11.2-26.2 ww Waldock (1983)
River Usk United Kingdom 1974 30 000 dw Eglinton et al. (1975)
a dw = dry weight; ww = wet weight; ns = not stated whether concentrations refer to dry or wet weight
In Japan, the levels of sediments in rivers and seas in 1982
ranged from 9 to 35 000 µg/kg dry weight (Environment Agency of Japan,
1989).
5.1.5 Soil
Contaminated soil analysed in the Netherlands was found to
contain up to 1.5 mg DEHP/kg (Wams 1987), while residues of DEHP in
soil collected in the vicinity of a DEHP manufacturing plant contained
up to 0.5 mg/kg (Persson et al., 1978).
Fatoki & Vernon (1990) reported a DEHP concentration of 1.9
µg/litre in treated sewage effluent from the Manchester area, United
Kingdom, and stated that such a level was consistent with the
industrial activities of the city.
5.1.6 Food
DEHP has been found in many samples of fish and shellfish (see
Table 6). It has also been detected in milk (Cerbulis & Ard, 1967),
bovine pineal gland (Taborsky, 1967), bovine heart muscle (Nazir et
al., 1971), and chicken eggs (Ishida et al., 1982). Perkins (1967)
isolated a substance similar to DEHP from corn oil. The US ATSDR
(1988) quoted an US FDA survey of various foods in 1974 which showed
that DEHP levels in most foods were less than 1 mg/kg; the foods
surveyed included margarine, cheese, meat, cereal, eggs, milk, white
bread, canned corn, corn meal, and baked beans.
Ishida et al. (1981) collected and analysed chicken eggs
available in Japanese markets. DEHP levels in egg white ranged from
0.05 to 0.4 mg/kg, but no DEHP was detected in the egg yolk.
In a study by Antonyuk (1975), DEHP migration from PVC materials
into foodstuffs was noted following 7 days of contact. Levels of 4-16
mg DEHP/kg were detected in cheese, sausage, meat, flour, and rice
while after 30 days levels of 30-150 mg/kg were found in sunflower
oil. The permissible level of DEHP migration into foodstuffs was
considered to be 2.0 mg/kg. Zitko (1972) detected DEHP concentrations
in hatchery-reared juvenile Atlantic salmon of 13 to 16 mg/kg lipid;
fish food contained 8 to 9 mg/kg lipid. When Williams (1973) analysed
fish available to the Canadian consumer, only 6 out of 21 samples
contained measurable amounts of DEHP. Levels of 0.1 and up to 0.16
mg/kg were found in unprocessed eels and in processed canned tuna
fish, respectively.
Table 6. Concentrations of DEHP in biota
Organisms Location Country Concentration Reference
(µg/kg)a
Mollusc (digestive gland) Crouch Estuary, Essex United Kingdom 9.2-214 ww Waldock (1983)
Dragonfly naiads Iowa (industrial) USA 200 Mayer et al. (1972)
Commercial fish food North America 2000-7000 Mayer et al. (1972)
Channel catfish Mississippi & Arkansas USA 3200 Mayer et al. (1972)
(industrial)
Channel catfish Iowa (industrial) USA 400 Mayer et al. (1972)
Various fish species Japan 70-450 Kodama & Takai (1974)
Various fish species Japan < 50-1800 ww Kamata et al. (1978)
Various fish species various cities Japan 50-720 Goto (1979)
Mainly fish Gulf of Mexico < 1-135 Giam et al. (1978)
Various fish species (liver) Tees Bay United Kingdom 43-85.9 ww Waldock (1983)
Various fish species (muscle) Tees Bay United Kingdom 13-51.3 ww Waldock (1983)
Walleye Lake Superior, Ontario Canada 800 Mayer et al. (1972)
Tadpoles Iowa (industrial) USA 300 Mayer et al. (1972)
Common seal pup (blubber) 10 600 lw Zitko (1972)
a ww = wet weight; lw = lipid weight
5.1.7 Aquatic organisms
Ray et al. (1983a) found DEHP levels of up to 490 µg/kg in
sandworms (Neanthes virens) and up to 170 µg/kg in clams collected
from Portland, Maine, USA, but these levels did not seem to reflect
the sediment levels and local pollutant sources.
Musial & Uthe (1980) collected fish of various species from the
Gulf of St Lawrence, Canada, and analysed them for DEHP in lipid
extracts. They reported levels of up to 6.5 mg/kg on a wet weight
basis (51.3 mg/kg on fat weight basis) in mackerel muscle and up to
7.2 mg/kg (47.1 mg/kg fat weight) in herring muscle. Lower levels of
0.37 mg/kg (wet weight) were found in eels, and in both plaice and
redfish concentrations were less than 0.001 mg/kg.
Persson et al. (1978) collected aquatic organisms from the
vicinity of a DEHP factory in Finland. Invertebrates contained up to
0.1 mg DEHP/kg, and levels of 1.1 mg/kg in roach muscle and 2.3 mg/kg
in pike liver were measured. Thuren (1986) analysed biota near to an
industrial discharge point and reported levels of up to 5.3 mg/kg
(fresh weight) in Odonata sp and up to 14.4 mg/kg in Asellus
aquaticus.
In Japan, DEHP levels in various species of fish in rivers and
seas ranged from 0.01 to 19 mg/kg wet weight in 1974 (Environment
Agency of Japan, 1989).
5.1.8 Terrestrial organisms
Persson et al. (1978) analysed soil arthropods collected near a
DEHP factory in Finland and found residues of 2.8 mg/kg.
5.2 General population exposure
Few data are available on general population exposure.
Based on an analysis of DEHP levels in various foods, the average
exposure in the USA has been estimated to be around 0.3 mg/person per
day and the maximum 2 mg/person per day (see section 5.1.6).
In a survey of plasticizer levels in food-contact material and
food, the United Kingdom Ministry of Agriculture, Fisheries and Food
(MAFF, 1987) stated that DEHP has very limited use in food-contact
material, and the maximum daily intake from food sources has been
estimated to be less than 20 µg/person per day.
DEHP found in human tissues may be derived from medical devices,
since it was recognised by Trimble et al. (1966) and by Guess &
Haberman (1968) that DEHP is leached from certain medical devices.
Samples of soft PVC fluid bags containing normal saline and glucose
(50 mg/ml) were shaken for 24 h and analysed for plastic additives
(Smistad et al., 1989). The PVC plastic materials contained DEHP,
epoxidized vegetable oils, and stearates as the main additives. The
same components were found in the solutions. MEHP was also detected,
but only in the solutions.
Marcel & Noel (1970) reported the presence of phthalate esters in
human plasma that had been stored in plastic blood bags.
Jaeger & Rubin (1972) found that DEHP was extracted from PVC
plastic blood bags by human blood at the rate of 2.5 mg/litre per day
at 4 °C. The DEHP was found in both lipid-containing and lipid-free
fractions of plasma, whereas the red cells contained only minor
amounts. Seven out of twelve samples of lung tissue, taken at autopsy
from patients who had received transfusions of stored blood, contained
DEHP at concentrations of 13.4-91.5 mg/kg (dry weight). Rubin & Nair
(1972) reported that DEHP had also been found in the tissues and urine
of patients who had not received blood transfusions, but no details
were given. Mes et al. (1974) analysed human adipose tissue in Canada
and found the levels of DEHP in most samples to range from 0.3 to 1.0
mg/kg.
Schneider et al. (1989) estimated that the highest exposure to
DEHP associated with medical devices resulted from extracorporeal
membrane oxygenation (ECMO), which could result in an exposure of 14
mg/kg per day. In an infant receiving ECMO for 14 and 24 days, the
DEHP serum levels were 26.8 and 33.5 mg/litre, respectively. In
another infant, ECMO for 6 days resulted in liver, heart, and
testicular concentrations of 3.5, 1.0, and 0.4 mg/kg, respectively.
Newborn infants given exchange transfusions may have plasma
levels of about 10 mg/litre (Sjöberg et al., 1985b).
5.3 Occupational exposure during manufacture, formulation or use
Few data on occupational exposure to DEHP have been reported.
In a phthalate manufacturing plant in the USA producing DEHP from
phthalic anhydride and alcohols, Liss et al. (1985) measured, in the
case of six heavily exposed workers, 8-h TWA workplace air
concentrations of DEHP ranging from 0.02 to 4.1 mg/m3. The exposure
level for 44 other workers in the same plant was below the detection
limit (10 µg/sample).
In an Italian factory producing n-butyl phthalate, isobutyl
phthalate, and DEHP, Gilioli et al. (1978) measured total phthalate
exposure concentrations of between 1 and 60 mg/m3, the average being
5 mg/m3.
Nielsen et al. (1985) measured total phthalic acid esters in air
in a PVC-processing plant in Sweden where diisodecyl phthalate, DEHP,
and some butylbenzylphthalate were used. Concentrations of between
0.01 and 2.0 mg/m3 were recorded in 96 2-h personal samples from 54
workers.
Total phthalates concentrations in air of between 1.7 and 66
mg/m3 were recorded in a PVC-processing plant in the USSR using
mainly dibutyl phthalate and higher alkyl phthalates but also some
DEHP and other phthalates (Milkov et al., 1973). Stankevich & Zarembo
(1978) measured DEHP levels of 1.5 to 40 mg/litre in the blood of
workers manufacturing PVC in the USSR.
DEHP concentrations in air of between 0.09 and 0.16 mg/m3 were
recorded in a German factory for phthalate production (Thiess et al.,
1978a). In 9 PVC-processing plants in Finland, the mean concentration
of DEHP ranged from less than 0.02 mg/m3 to 0.5 mg/m3 and the
highest single value was 1.1 mg/m3 (Vainiotalo & Pfäffli, 1990).
6. KINETICS AND METABOLISM IN LABORATORY ANIMALS AND HUMANS
6.1 Absorption
6.1.1 Inhalation
There is no quantitative information available on the pulmonary
route of absorption, although aerosols of DEHP are readily formed
(Albro & Lavenhar, 1989).
6.1.2 Dermal
After a single application of 14C-labelled DEHP (61.5 mg/kg) to
the back of F-344 rats, clipped one hour before treatment, urine and
faeces were collected every 24 h for 7 days. The amount of 14C
excreted was taken as an index of the percutaneous absorption, and
about 5% of the dose given was excreted (Elsisi et al., 1989).
6.1.3 Oral
Studies with 14C-labelled DEHP indicated that at least 50% of
the radioactivity of a single dose (2.9 mg/kg) was absorbed in the rat
intestine since 42% and 14% were excreted in urine and bile,
respectively, after 7 days (Daniel & Bratt, 1974). The same authors
also found that DEHP was rapidly hydrolysed by pancreatic lipase,
suggesting that DEHP is hydrolysed in the gut before absorption. This
was supported by the fact that no unmetabolized DEHP was found in
liver after the administration of low oral doses (< 0.4 g/kg),
although at higher doses (> 0.5 g/kg) DEHP was detected (Albro et
al., 1982). At an oral dose level of 2 g/kg, the bioavailability of
DEHP in rats, as measured in blood by HPLC, was 14%, whereas at an
intraperitoneal dose level of 4 g/kg only 5% was recovered, again
indicating a role for hydrolysis of DEHP in the gut (Pollack et al.,
1985b). Using an inhibitor of mucosal esterases ( S,S,S-tributyl
phosphorothionate), White et al. (1980) observed a marked inhibition
in the uptake of DEHP by the gut. Studies involving oral
administration of MEHP indicated that this metabolite is well
absorbed. After radiolabelled MEHP or DEHP was given to rats, the
radioactivity recovered in plasma from MEHP was 16 times more than
that from DEHP (Teirlynck & Belpaire, 1985).
Oral administration of DEHP (1 g/kg) to young rats leads to a
larger area under the plasma concentration-time curve (measured with
gas chromatography) for MEHP (twice that of DEHP) than in older rats
(Sjöberg et al., 1985a). This indicates either a more rapid hydrolysis
of DEHP or a more efficient absorption of MEHP in young rats.
Cynomolgus monkeys hydrolyse DEHP in the gut less efficiently
than rats or mice (Astill, 1989). Rhodes et al. (1986) also noted that
there is less absorption from the gastrointestinal tract in marmosets
than in rodents.
6.1.4 Intraperitoneal
The systemic availability of DEHP was only 5% when a dose of 4
g/kg was given intraperitoneally to rats. Relatively small amounts of
MEHP were recovered in the blood in this study (Pollack et al.,
1985b).
6.2 Distribution
Intravenously administered DEHP is rapidly eliminated from blood.
This was demonstrated in experiments where radioactive DEHP was
injected into male CFN rats and blood levels were determined by thin-
layer chromatography (Schulz & Rubin, 1973). At a low dose level (0.1
mg/kg), there was an initial phase with a half-time of 4.5 min and a
second phase with a half-time of 22 min. At a higher dose level (200
mg/kg) the initial phase had a half-time of 9 min. This indicated that
DEHP was taken up in a tissue compartment by a saturable process
(Schulz & Rubin, 1973). Radioactivity from DEHP was rapidly
distributed to the liver, lungs, and spleen when administered
intravenously (Schulz & Rubin, 1973; Daniel & Bratt, 1974).
Orally administered DEHP is mainly distributed as MEHP in rats
(Pollack et al., 1985b; Teirlynck & Belpaire, 1985). Unmetabolized
DEHP was recovered in the liver only after large oral doses
(> 0.5 g/kg) were given, indicating a threshold phenomenon in the
absorption and distribution (Albro et al., 1982; Agarwal, 1986). The
distribution kinetics of MEHP have been analysed by Pollack et al.
(1985b) and by Teirlynck & Belpaire (1985). Pollack et al. (1985b)
found that the peak concentration of MEHP in blood was reached 15 min
after oral or intraperitoneal administration of MEHP. The half-time of
MEHP in blood or plasma in the rat is shorter than that of DEHP
(Pollack et al., 1985b; Teirlynck & Belpaire, 1985). The in vitro
plasma protein binding of MEHP in the rat reaches approximately 98%
(Sjöberg et al., 1985a).
A phenomenon known as "shock-lung" has been reported to occur
following intravenous administration of DEHP to rats and other
species. Two hours after an emulsion of DEHP was given, between 13%
and 48.6% of DEHP-radiolabelled material was found in the lungs of
rats, as compared to 26.3-38.2% in the liver (Daniel & Bratt, 1974).
This phenomenon may be relevant to human exposure via intravenous
administration from bags and tubing containing DEHP.
The DEHP plasma level in newborn infants given exchange
transfusions may reach about 10 mg/litre (Sjöberg et al., 1985b).
This level is about twice as high as those found in leukaemia patients
receiving platelet concentrations and about five times as high as
levels found in haemodialysed patients. After treatment, this level
falls rapidly to about 3 mg/litre within 2 h, and then there is a
further drop with a half-time of about 10-12 h (Sjöberg et al.,
1985b).
6.3 Metabolism
DEHP is hydrolysed in vitro by pancreatic lipase to MEHP
(Daniel & Bratt, 1974), indicating that this metabolism would occur
mainly in the gut lumen. In rats about 80% of an oral dose of DEHP
undergoes mono-deesterification (Pollack et al., 1985b), while intra-
arterially administered DEHP is only slowly converted to MEHP (Pollack
et al., 1985b). Studies on the hydrolysis of DEHP in homogenates from
different organs (Table 7) indicate a very high activity in pancreatic
juice and a comparatively low activity in liver (Albro & Thomas, 1973;
Daniel & Bratt, 1974).
At relatively high doses of DEHP (2 g/kg body weight per day),
administered by gavage for up to 14 days, approximately 25-40% of the
dose in rats and 50-75% of the dose in marmosets was excreted in the
faeces. This implies that incomplete intestinal hydrolysis and
absorption may occur (Rhodes et al., 1986).
MEHP may in turn be metabolized in the gut wall (Pollack et al.,
1985b) or in other organs. Rat liver cell cultures have been shown to
convert MEHP to several metabolites, as occurs in the intact rat
(Albro et al., 1973; Lhuguenot et al., 1985). Cultures of testicular
cells were, however, apparently not able to metabolize MEHP beyond
slight hydrolysis to phthalic acid within 18-24 h (Albro et al.,
1989).
The metabolic pathways for MEHP are shown in Fig. 1. The omega-
and omega-1-carbon oxidation products constitute more than 85% of the
metabolites (Albro et al., 1973; Mitchell et al., 1985a; Lhuguenot et
al., 1985). The ethyl side chain may also be oxidized (Lhuguenot et
al., 1985). It has been suggested that omega-oxidation leads to a
metabolite that is further degraded by ß-oxidation in the peroxisomes
(Albro et al., 1973; Lhuguenot et al., 1985). Non-linear dose-
dependency has been reported for these pathways in the rat; the
predominance of omega-oxidation over omega-1-oxidation was increased
by high doses of MEHP (Lhuguenot et al., 1985).
The administration of 2-ethyl-(1-14C)-hexyl-labelled DEHP led
to a low level of radioactivity being recovered from purified rat
liver DNA (Albro et al., 1982). In a more recent study (Lutz, 1986),
the administration of 14C-carboxylate-labelled DEHP resulted in no
measurable radioactivity in DNA, whereas radioactivity was clearly
measurable after the administration of DEHP that was 14C- or
3H-labelled in the alcohol moiety.
Table 7. DEHP hydrolase activity of various tissue lipasesa
DEHP hydrolase activity
Enzyme preparation
units/mg protein units/g tissue
Liver acid lipase, homogenate 0.34 101
Liver alkaline lipase, homogenate 0.14 43
Liver "lysosomal" concentrate (acacia)b 8.80 -
Liver microsome + supernatant fraction, pH 8.2 1.22 -
Kidney acid lipase, homogenate 0.15 45
Lung homogenate (cholate)b 0.072 15
Lung homogenate (acacia)b 0.10 21
Mucosal homogenate, pH 7.4 0.86 83
Muscosal homogenate, pH 9.0 0.43 41
Pancreas homogenate 54.9 34 400
Adipose "monoglyceride lipase" 0.021 0.53
Adipose "hormone-sensitive lipase" 0.14 0.82
Purified cholesteryl esterase 0 -
a From: Albro & Thomas (1973)
b 14C-labelled DEHP supplied as dispersion in either sodium cholate or
gum acacia
There are marked species differences in the metabolism of DEHP.
Thus omega-oxidation seems to play a dominante role in the rat and
guinea-pig (Albro et al., 1982; Lhuguenot & Elcombe, 1984; Lhuguenot
et al., 1985), but to be a minor pathway in the mouse, hamster, green
monkey, cynomolgus monkey, and marmoset (Albro et al., 1982; Lhguenot
& Elcombe, 1984). In guinea-pigs there are few omega-1 metabolites of
MEHP (Albro et al., 1982). This may have toxicological significance
because certain omega-1-oxidation metabolites have been identified as
active agents in peroxisomal proliferation in rat hepatocytes
(Mitchell et al., 1985a).
No conjugated metabolites were detected in the urine of
DEHP-treated rats, but a minor portion was conjugated in the urine of
hamsters (Albro et al., 1982; Lhuguenot & Elcombe, 1984). A major
portion of glucuronide conjugates was found in the urine of the
marmoset, mouse, guinea-pig, and green monkey, and in human urine
(Albro et al., 1982). Albro (1986) reported that glucuronidation of
DEHP metabolites was insignificant in rats. Studies in primates,
including the African green monkey (Albro et al., 1981), marmoset
(Rhodes et al., 1986), cynomolgus monkey (Short et al., 1987; Astill,
1989), and man (Schmid & Schlatter, 1985), demonstrated that
conjugation of DEHP can occur at the carboxylic acid moiety following
a single ester hydrolysis.
The level of unmetabolized MEHP excreted in urine also varies
considerably between species; it is low in the rat and hamster, but
high in the mouse, guinea-pig, green monkey, and man (Albro et al.,
1982).
Repeated oral administration of DEHP or MEHP at high doses (500
mg/kg) to rats leads to a change in the metabolic profile; there is an
increase in omega-oxidized metabolites and a decrease in
omega-1-oxidized metabolites (Lhuguenot et al., 1985). In rats given
2% DEHP in the diet for one week, a 4-fold increase in peroxisomal ß-
oxidation was found. ß-Oxidation of fatty acids induced by DEHP
appears to occur via mitochondrial and peroxisomal pathways that are
similar to normal pathways (Ganning et al., 1989). Drug-metabolizing
enzyme activities have been studied after DEHP administration, and in
some cases changes were observed (Walseth et al., 1982; Agarwal et
al., 1982; Gollamudi et al., 1985; Pollack et al., 1989).
The same metabolites as those found in rat urine can be detected
in human urine. One study on intravenously injected DEHP (Albro et
al., 1982) and one on orally administered DEHP (Schmid & Schlatter,
1985) indicated that humans metabolize DEHP by omega- and
omega-1-oxidation as well as by oxidation of the ethyl side chain.
However, the omega-oxidation-pathway seems to be a minor pathway in
man (Albro et al., 1982; Schmid & Schlatter, 1985). More than half of
the metabolites recovered in human urine are conjugated metabolites
(Albro et al., 1982; Schmid & Schlatter, 1985).
Time-averaged concentrations of DEHP, MEHP, and phthalic acid in
the blood of patients undergoing maintenance haemodialysis were 1.9,
1.3, and 5.2 mg/litre, respectively (Pollack et al., 1985a). Such
patients are considered to be at risk of potential DEHP toxicity
through prolonged contact with medical plastic products that contain
DEHP. The relatively high circulating level of phthalic acid may
indicate an altered metabolism of DEHP in uraemic patients (Pollack et
al., 1985a).
The levels of DEHP and MEHP in plasma have been studied in
newborn infants given blood exchange transfusions. In one case the
MEHP half-life was the same as for DEHP (about 12 h), indicating that
the hydrolysis of DEHP was the rate-limiting metabolic step. However,
in other children the half-time of MEHP was longer than that of DEHP
(Sjöberg et al., 1985b).
6.4 Elimination and excretion
Radioactivity from intravenously injected 14C-labelled DEHP is
mainly recovered in urine and faeces after 24 h (Schulz & Rubin,
1973), indicating that urine and bile are major excretory pathways.
When a low dose level (0.1 mg/kg) was given to rats, 50-60% of
injected radioactivity was recovered in urine and faeces after 24 h,
whereas at a high dose level (200 mg/kg) less than 50% was recovered
(Schulz & Rubin, 1973). Seven days after an oral dose (2.9 mg/kg) of
DEHP was given to rats, 42% of the radioactivity was recovered in the
urine and 57% in the faeces (Daniel & Bratt, 1974). Biliary excretion
was also measured in these experiments, and it was found that 14% of
the radioactivity was recovered in bile after 4 days (Daniel & Bratt,
1974). The almost 100% recovery reported by Daniel & Bratt (1974) has
been confirmed by Teirlynck & Belpaire (1985). Oral administration of
MEHP (50-500 mg/kg) gave a higher urinary recovery than orally
administered DEHP (50-500 mg/kg) as measured after 24 h (Lhuguenot et
al., 1985).
After the oral administration of non-radioactive DEHP (0.45
mg/kg) to human volunteers, it was found that 15-25% was excreted in
urine as MEHP or oxidized metabolites within 2-3 days (Schmid &
Schlatter, 1985).
In the rat no unmetabolized DEHP is excreted in the urine, but
small amounts are found in mouse or green monkey urine (Albro et al.,
1982). Major amounts of MEHP are excreted in mouse, guinea-pig, green
monkey, and human urine (Albro et al., 1982). However, oxidized
metabolites, either free or conjugated, constitute a major portion of
excretion products in rat, mouse, hamster, green monkey, and human
urine (Albro et al., 1982).
Changes in excretion pathways have been observed after prolonged
administration of DEHP. After oral dosing of rats without
pre-treatment with DEHP, the faecal excretion pathway dominated, while
in rats fed with DEHP for 7 days the urinary pathway dominated (Daniel
& Bratt, 1974).
6.5 Retention and turnover
6.5.1 Half-life and body burden
After the intravenous administration of radiolabelled DEHP, at
least two elimination phases of radioactivity, with short half-lives
(4.5-9 and 22 min, respectively), were observed in rat blood (Schulz
& Rubin, 1973). After 7 weeks of oral administration, the elimination
phase in the liver was considerably slower, the half-life being 3-5
days (Daniel & Bratt, 1974). No accumulation of DEHP or MEHP was
observed when the dosage was 2.8 g/kg per day for 7 days (Teirlynck &
Belpaire, 1985), nor was there any in a long-term (5-7 weeks) feeding
study at a dose level of 1 or 5 g/kg diet (corresponding to a daily
dose of about 50 and 250 mg/kg body weight) (Daniel & Bratt, 1974).
6.5.2 Indicator media
Analysis of the total amount of urinary metabolites, measured as
derivatized phthalic acid, indicate a weak positive correlation
between occupational exposure to phthalate and the presence of
metabolites in the urine (Nielsen et al., 1985; Liss et al., 1985). In
the study by Nielsen et al. (1985), workers were exposed mainly to
DEHP and diisodecyl phthalate, and the urinary level of phthalate
ester metabolites rose from the background level (17 µmol/litre) to
23-25 µmol/litre. In the study by Liss et al. (1985), workers were
exposed to DEHP and phthalic anhydride. Urinary phthalate
concentrations in exposed workers more than doubled after a workshift
and levels up to 44 µmol/litre were recorded. The authors concluded
that phthalic anhydride influenced the urinary level more than DEHP.
Phthalic acid is not a specific marker for DEHP exposure.
7. EFFECTS ON LABORATORY MAMMALS AND IN VITRO TEST SYSTEMS
7.1 Single exposure
Numerous LD50 values have been reported for DEHP. Oral LD50
values generally exceed 25 g/kg in rats and 30 g/kg in mice
(Stankevich et al., 1984; NIOSH, 1985b; Woodward et al., 1986); in the
rabbit it is 33.9 g/kg (Shaffer et al., 1945) and in the guinea-pig
26.3 g/kg (Krauskopf, 1973). Dermal LD50 values for guinea-pigs and
rabbits of 10 g/kg and 25 g/kg, respectively, have been reported
(NIOSH, 1985b).
The LD50 values after intraperitoneal administration were
30.7 g/kg in rats (Shaffer et al., 1945) and 14-75 g/kg in mice
(Lawrence et al., 1975; Woodward et al., 1986). LD50 values in the
range of 200-250 mg/kg were reported for the rat after intravenous
administration of DEHP solubilized with a nonionic detergent (Schmidt
et al., 1975; Rubin & Chang, 1978).
The main symptom of DEHP toxicity after single oral or
intraperitoneal dosing is diarrhoea (Hodge, 1943). An intraperitoneal
dose of 500 mg/kg in rats decreased spontaneous running activity,
thereby indicating behavioural changes (Rubin & Jaeger, 1973). After
intravenous dosing, lung lesions including oedema, haemorrhage, and
infiltrations of polymorphonuclear leucocytes were observed in rats at
doses as low as 50 mg/kg (Schulz et al., 1975). The etiology of the
lung lesions is unknown. It has, however, been suggested that some
changes could be due to the release of lysosomal enzymes from alveolar
macrophages, which was found to occur in vitro in rabbit alveolar
macrophages cultured with DEHP (Bally et al., 1980).
Rabbits treated intravenously with 350 mg DEHP/kg showed a
decrease in blood pressure and an increase in breathing rate. No
deaths occurred after doses up to 650 mg/kg were administered (Calley
et al., 1966).
The monoester, MEHP, may be more toxic than the diester but data
are very limited. In a short note by Villeneuve et al. (1978), the
oral LD50 of MEHP was reported to be 1.34 g/kg in female rats and
1.8 g/kg in males.
7.2 Short-term exposure
Doses of 3.4 g/kg body weight per day given by gavage (in olive
oil) for periods of up to 90 days caused the death of 15 out 20 rats
(Nikonorow et al., 1973). However, no deaths were reported among rats
fed 3% DEHP in the diet (1.9 g/kg body weight) for 90 days (Shaffer et
al., 1945) or in a rat study of the US National Toxicology Program
after dietary dosing (< 50 g/kg) for 14 days (NTP, 1982).
Oral administration of DEHP at a rate of > 0.4 g/kg body
weight per day resulted in a weight gain decrease in rats within a few
days (Nikonorow et al., 1973). In a 17-week feeding study where rats
were given 2, 10 or 20 g DEHP/kg diet, a decreased body weight was
observed (Gray et al., 1977). Reduction in body weight was also
observed in rats given dietary levels of 12.5 or 25 g/kg for 13 weeks.
Dosages of 1.6-6.3 g/kg resulted in either slight elevations of body
weight or no effect (NTP, 1982).
MEHP given at a level of 6.4 g/kg diet caused reduction in the
body weight gain of rats (Chu et al., 1981). No effects on body weight
occurred at dietary levels of 0.625 g/kg given for 3 months, but a
significant decrease in blood glucose was observed.
Reductions in haemoglobin, packed cell volume and erythrocyte
numbers were observed in rats given 10 or 20 g DEHP/kg diet for 17
weeks, but not when they were given 2 g/kg for the same period (Gray
et al., 1977).
Cystic kidneys and centrilobular necrosis were noted in one
strain of mice (ddY) fed 2.5 or 25 g DEHP/kg for 2 weeks, but not in
another strain (B6C3F1), even with a higher exposure level and a
longer exposure period (Woodward et al., 1986).
DEHP administered intravenously at a rate of 25-500 mg/kg per day
for 2-4 weeks to beagle dogs resulted in pulmonary haemorrhage and
inflammatory response similar in appearance to the "shock-lung" effect
(Woodward et al., 1986).
In an inhalation study, Wistar rats were exposed in a head-nose
inhalation system to DEHP aerosols of respirable particle size.
Exposure duration was 6 h/day, 5 days/week for 4 weeks at target
concentrations of 0, 0.01, 0.05, and 1.0 mg/litre. A statistically
significant increase in relative lung weights was found in the males
given the highest dosage, and this was accompanied by foam cell
proliferation and thickening of the alveolar septa (Klimisch et al.,
1991).
Another inhalation study has been reported, but this is
inadequate for assessment (Timofievskaja et al., 1980).
A discussion of the effects of DEHP on the liver is given in
section 7.9.
When rats were treated with DEHP by intraperitoneal injection
(Walseth et al., 1982) or by repeated oral dosing (Agarwal et al.,
1982), an increase in cytochrome P-450 levels was observed. The
increase in hepatic microsomal oxidation appears to be primarily due
to the deesterification products of DEHP, i.e. MEHP and
2-ethoxyhexanol, in long-term exposure, whereas DEHP and its two
metabolites may inhibit microsomal oxidation after acute exposure to
DEHP (Pollack et al., 1989). However, in vitro rat liver microsomal
cytochrome P-450 levels were not affected by DEHP (Gollamudi et al.,
1985).
Liver mitochondrial enzymes and mitochondrial morphology have
been reported to be influenced by DEHP administration (Ohyama, 1977;
Shindo et al., 1978). Recent results suggest that the in vitro
effects of DEHP (> 20 µmol/litre) on mitochondrial functions are
mainly related to the action on membrane lipids surrounding the
adenine nucleotide translocator, which reduces the rate of adenine
nucleotide exchange across the mitochondrial membrane (Kora et al.,
1989).
In male rats given DEHP in the diet, the urinary excretion of
zinc was enhanced and the testicular level of zinc decreased (Gray et
al., 1982; Oishi, 1985) (section 7.5). These changes in zinc
homeostasis could be due to altered levels of metallothionein. In mice
fed 6 or 12 g DEHP/kg diet for 24 weeks, hepatic levels of
metallothionein were increased up to 11-fold (Waalkes & Ward, 1989).
Several studies on rats have shown that DEHP given in the diet
(5-20 g/kg) decreases plasma triglyceride and cholesterol levels
(Yanagita et al., 1978; Sakurai et al., 1978; Bell et al., 1978a; Bell
et al., 1978b; Bell et al., 1979; Yanagita et al., 1979; Curstedt &
Sjövall, 1983). DEHP inhibits the biosynthesis of cholesterol, an
effect which is accompanied by phospholipidosis, and the same effects
have been observed with MEHP (Oishi & Hiraga, 1982).
7.3 Long-term exposure
In a 24-month study by Harris et al. (1956), three groups of
Wistar rats each comprising 43 males and 43 females were fed diets
containing 0, 1, and 5 g DEHP/kg, interim kills being made at 3, 6,
and 12 months. At the end of the study, only two control, four
low-dose, and seven high-dose animals were alive. During the first
year the body weights of the high-dose group were slightly reduced,
but by the second year the body weights of all groups were similar.
During the first 6 months an increase in relative liver and kidney
weights was seen in DEHP-treated animals but later they were similar
in control and treated animals. After 3 months of treatment, one out
of eight rats in the low-dose group was found to have mild renal
tubular atrophy. After 6, 12, and 24 months of treatment, no
compound-related pathological changes were evident. Because of high
mortality due to disease, this study is difficult to validate.
In another 24-month study (Carpenter et al., 1953), groups of
Sherman rats consisting of 32 males and 32 females were given diets
containing 0, 0.4, 1.3 or 4 g DEHP/kg. Owing to reduced life
expectancy due to disease and the small numbers of animals used, the
study was inadequate for assessing the chronic toxicity of DEHP.
In a 12-month study by Nikonorow et al. (1973), a group of 20
male and 20 female Wistar rats was given a diet containing 3.5 g
DEHP/kg, and a control group received the diet without DEHP. The only
gross or micropathological change noted in exposed animals at necropsy
was hepatomegaly. During the study, however, about 30% of the animals
died due to congestion of the small intestine and loss of the gastric
and/or intestinal mucosa, which was complicated by purulent pneumonia
and endometritis.
Crocker et al. (1988) described the renal effects of DEHP given
by gavage to young male rats at a dosage of 2.14 mg/kg body weight
three times per week for up to 12 months. A 50% reduction in
creatinine clearance and an increase in the severity of renal cyst
formation was observed. This lesion was consistent with spontaneous
nephropathy commonly observed in old rats; exposure may cause an onset
in younger rats. Furthermore, DEHP fed at 6 and 12 g