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    IPCS INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY
    Health and Safety Guide No. 106

    PHOSGENE
    HEALTH AND SAFETY GUIDE






    UNITED NATIONS ENVIRONMENT PROGRAMME

    INTERNATIONAL LABOUR ORGANISATION

    WORLD HEALTH ORGANIZATION




    WORLD HEALTH ORGANIZATION, GENEVA 1998

    IPCS

    Health and Safety Guide No. 106

    PHOSGENE
    HEALTH AND SAFETY GUIDE

    This is a companion volume to
    Environmental Health Criteria 193: Phosgene


    Published by the World Health Organization for the International
    Programme on Chemical Safety (a collaborative programme of the United
    Nations Environment Programme, the International Labour Organisation,
    and the World Health Organization) and produced within the framework
    of the Inter-Organization Programme for the Sound Management of
    Chemicals

    WORLD HEALTH ORGANIZATION, GENEVA 1998

    This is a companion volume to Environmental Health Criteria : Phosgene

    Published by the World Health Organization for the International
    Programme on Chemical Safety (a collaborative programme of the United
    Nations Environment Programme, the International Labour Organisation,
    and the World Health Organization)

    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

    WHO Library Cataloguing in Publication Data

    Health and safety guide for Phosgene

    (Health and safety guide ; no. 106)

    1.Phosgene - toxicity  2.Environmental exposure
    3.Guidelines           I.International Programme on Chemical Safety
    II.Series

    ISBN 92 4 15106 0          (NLM Classification: QV 664)
    ISSN 0259-7268

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

    (c) World Health Organization 1998

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

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

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

    CONTENTS

    INTRODUCTION

    1. PRODUCT IDENTITY AND USES

         1.1. Identity
         1.2. Physical and chemical properties
         1.3. Conversion factors
         1.4. Analytical methods
         1.5. Production, uses and occurrence

    2. SUMMARY AND EVALUATION

         2.1. Exposure
         2.2. Environmental fate
         2.3. Kinetics and metabolism
         2.4. Effects on organisms in the environment
         2.5. Effects on animals and  in vitro test systems
         2.6. Effects on humans

    3. CONCLUSIONS

         3.1. Human health
         3.2. Environment

    4. HUMAN HEALTH HAZARDS, PREVENTION AND PROTECTION, EMERGENCY
         RESPONSE

         4.1. Human health hazards, prevention and protection, first aid
               4.1.1. Advice to physicians
                       4.1.1.1   Symptoms of poisoning
                       4.1.1.2   Medical treatment
               4.1.2. Health surveillance advice
         4.2. Explosion and fire hazards
         4.3. Storage
         4.4. Transport
         4.5. Spillage and disposal
               4.5.1. Spillage
               4.5.2. Disposal
         4.6. Other protective measures

    5. HAZARDS FOR THE ENVIRONMENT AND THEIR PREVENTION

    6. SUMMARY OF CHEMICAL SAFETY INFORMATION

    7. CURRENT REGULATIONS, GUIDELINES AND STANDARDS

         7.1. Occupational exposure limit values
         7.2. Labelling, packaging and transport

    BIBLIOGRAPHY
    

    INTRODUCTION

    The Environmental Health Criteria (EHC) monographs produced by the
    International Programme on Chemical Safety include an assessment of
    the effects on the environment and on human health of exposure to a
    chemical or combination of chemicals, or physical or biological
    agents.  They also provide guidelines for setting exposure limits.

    The purpose of a Health and Safety Guide is to facilitate the
    application of these guidelines in national chemical safety
    programmes.  The first three sections of a Health and Safety Guide
    highlight the relevant technical information in the corresponding EHC. 
    Section 4 includes advice on preventive and protective measures and
    emergency action; health workers should be thoroughly familiar with
    the medical information to ensure that they can act efficiently in an
    emergency.  Within the Guide is a Summary of Chemical Safety
    Information which should be readily available, and should be clearly
    explained, to all who could come into contact with the chemical.  The
    section on regulatory information has been extracted from the legal
    file of the International Register of Potentially Toxic Chemicals
    (IRPTC) and from other United Nations sources.

    The target readership includes occupational health services, those in
    ministries, governmental agencies, industry, and trade unions who are
    involved in the safe use of chemicals and the avoidance of
    environmental health hazards, and those wanting more information on
    this topic.  An attempt has been made to use only terms that will be
    familiar to the intended user.  However, sections 1 and 2 inevitably
    contain some technical terms.  A bibliography has been included for
    readers who require further background information.

    Revision of the information in this Guide will take place in due
    course, and the eventual aim is to use standardized terminology. 
    Comments on any difficulties encountered in using the Guide would be
    very helpful and should be addressed to:

    The Director
    International Programme on Chemical Safety
    World Health Organization
    1211 Geneva 27
    Switzerland

    THE INFORMATION IN THIS GUIDE SHOULD BE CONSIDERED AS A STARTING
    POINT TO A COMPREHENSIVE HEALTH AND SAFETY PROGRAMME

    1.  PRODUCT IDENTITY AND USES

    1.1  Identity

    Common name:             
                             Phosgene

    Common synonyms:         carbonyl chloride, carbonic acid dichloride,
                             carbon oxychloride, chloroformyl chloride

    Molecular formula:       
                             COC12

    Chemical structure:

                             Cl
                                \
                                  C = O
                                /
                             Cl

    IUPAC name:              
                             carbonic dichloride

    CAS name:                
                             carbonic dichloride

    CAS registry number:     75-44-5

    RTECS registry number:   SY 5600000

    UN transport number:     UN 1076

         Technical grade phosgene has a purity between 95 and 99%
    depending upon the intended local use.  Impurities include nitrogen,
    carbon monoxide, hydrochloric acid, free chlorine and sulfur
    compounds.

    1.2  Physical and chemical properties

         Phosgene is a colourless gas at room temperature and standard
    pressure.  It has a suffocating odour similar to mouldy hay.  Although
    the odour of phosgene can be perceived at 1.6 mg/m3 (0.4 ppm), after
    adaption recognition will be at levels >6 mg/m3 (1.5 ppm).  It is
    slightly soluble in water and freely soluble in most liquid
    hydrocarbons, benzene, toluene and glacial acetic acid.

         In water, phosgene is sparingly soluble and decomposes to
    hydrochloric acid and carbon dioxide.  It also reacts with ethanol but
    is soluble unaltered in benzene, toluene, most liquid hydrocarbons,
    and in glacial acetic acid.

         Phosgene decomposes on heating above 300 C producing chlorine
    and carbon monoxide.  It is formed by thermal decomposition of
    chlorinated solvents, e.g., chloroform, carbon tetrachloride, tri- and
    tetra-chloroethylene and methylene chloride, as well as by the thermal
    degradation of chlorinated polymers. Some of its physical properties
    are as follows:

         Melting point (C)                 -127.8
         Boiling point (C)                 7.56
         Relative density (water = 1)       1.4
         Relative vapour density (air = 1)  3.42
         Vapour pressure (20 C)            161.6 kPa

    1.3  Conversion factors

         1 ppm = 4.05 mg phosgene/m3 air
         1 mg phosgene/m3 = 0.25 ppm
         at 25 C and 101.3 kPa

    1.4  Analytical methods

         Phosgene in air may be detected by ultraviolet spectrophotometry,
    gas chromatography, infrared spectrophotometry, automated colorimetry
    and paper tape monitors containing 4-(4-nitrobenzyl)-pyridine and
     n-benzylaniline, both for personal badges and in continuous
    monitoring.  Monitoring methods should provide data on accumulated
    exposure levels over time, preferably on a continuous basis.

    1.5  Production, uses and occurrence

         Phosgene is produced by reacting equimolar amounts of carbon
    monoxide and anhydrous chlorine in the presence of a carbon catalyst
    under appropriate conditions of temperature and pressure.  The great
    majority is used directly in closed systems on-site.

         Phosgene is used as an intermediate in the manufacture of many
    organic chemicals.  The largest amount (approximately 80% of world
    production) is used to produce toluene diisocyanate and other
    isocyanates used in polyurethane foam production, preparation of
    plastics, and pesticides. Accurate production figures are hard to
    determine since over 99% of phosgene production is "used on site". 
    Approximately 3106 tonnes of phosgene are used annually worldwide.

         Phosgene levels in ambient air can arise from the thermal and
    photo-degradation of chlorinated solvents and chlorinated polymers. 
    The major source of phosgene is the photochemical oxidation of
    chloroethylenes such as tri- and tetra-chloroethylene.  Accidental
    releases from industries will affect only areas around the plant and
    not usually the general environment.

    2. SUMMARY AND EVALUATION

    2.1  Exposure

         Human exposure to phosgene is by inhalation.  Potential sources
    of exposure include the production and use of phosgene, ambient air
    and from the photo and thermal degradation of chlorinated solvents and
    polymers.

         Although few data are available, average ambient air values vary
    between 80 and 130 ng/m3.  The total daily intake would thus be
    between 1.6 and 2.6 g.  Much higher levels of phosgene exposure are
    possible during the home use of chlorinated solvents, e.g., methylene
    chloride, under conditions where temperatures are sufficiently high to
    lead to thermal degradation.

         Data are inadequate to determine quantitatively the exposure to
    phosgene in the workplace.  However, those working simultaneously with
    flames and/or thermal energy sources and organochlorine solvents or
    chlorinated polymers can be exposed to phosgene levels well above the
    present threshold limit value (time-weighted average) of 0.4 mg/m3
    (0.1 ppm).

         Fire-fighters and workers engaged in welding and the building
    trade are at risk from levels of phosgene formed by the thermal
    degradation of chlorinated solvents and polymers.  Accidental release
    of phosgene during its manufacture, use or transport can lead to high
    levels of exposure in workers and in the general population in the
    vicinity of the accident.

    2.2  Environmental fate

         At normal ambient temperatures, the major pathway for phosgene
    degradation in air is gas-phase hydrolysis.  However, even at high
    levels of humidity, phosgene in air is only slowly degraded and is
    likely to be persistent in the atmosphere and subject to long-range
    transport.

         In water, phosgene is rapidly degraded to hydrochloric acid and
    carbon dioxide.

         Detectable levels of phosgene in soil and vegetation are unlikely
    due to heterogeneous abiotic degradation.

    2.3  Kinetics and metabolism

         There are very few data on the absorption, metabolism,
    distribution and fate of phosgene.  Exposure is by inhalation.  In
    view of the extremely short half-life (0.026 seconds) in aqueous
    solutions, and the penetration into the tissues of the respiratory

    tract by phosgene gas, only minimal amounts of phosgene are
    distributed in the body and no significant retention of phosgene in
    the body is possible.  The hydrolytic products of phosgene,
    hydrochloric acid and carbon dioxide, are disposed by the body through
    normal physiological processes.

         Phosgene exerts its toxicity through the acylation of proteins as
    well as through the release of hydrochloric acid.  The amino, hydroxyl
    and sulfhydryl groups in proteins appear to be the target for
    acylation, leading to marked inhibition of several enzymes related to
    energy metabolism and a breakdown of the blood:air barrier.

    2.4  Effects on organisms in the environment

         No information has been reported on the effects of phosgene on
    the environment.  However, the levels of phosgene now found in the
    general environment would not be expected to result in significant
    effects to aquatic or terrestrial biota.

         Damage to plants and aquatic organisms could occur in areas where
    accidental release of phosgene has occurred, owing to the rapid
    release of hydrochloric acid.

    2.5  Effects on animals and in vitro test systems

         In all species that have been studied, the lung is the major
    target organ.  After acute exposures of between 4 and 800 mg/m3
    (1-200 ppm) the toxicological effect is due to the exposure
    (C) x time (T) (Habers Law), based on studies of lung disease and
    death.  This relationship does not hold for chronic exposures.

         The L(CT)50 for single exposure was reported to vary widely
    among animal species, ranging from 900 mg/m3-min (225 ppm-min) in the
    mouse to 1920 mg/m3-min (250 ppm-min) in the monkey.  In all species
    the characteristic pathological feature was the dose-dependent
    clinical manifestation of pulmonary oedema.  The extent of the
    long-term chronic effects of acute exposure appears to depend on the
    severity of the initial pathology.  At low concentrations,
    pathological changes in the terminal bronchioles and alveoli were
    reported to be typical of a pulmonary irritant, whereas at higher
    levels pulmonary oedema occurred, leading to interference with gas
    exchange and death.

         Preliminary data from single 4-h exposures to 2 or 4 mg/m3 in
    rats and mice (480 mg/m3-min or 960 mg/m3-min) indicated a decrease
    in pulmonary immunocompetence.  No effects were seen at 0.4 mg/m3
    (96 mg/m3-min). Although limited, other data confirmed these
    findings. In rats exposed to 4 mg/m3 for 4 h (960 mg/m3-min), a
    10-fold increase in influenza virus titre was noted per day

    post-infection.  Pulmonary bacterial clearance was reduced in rats
    exposed for 6 h to 0.4 mg phosgene/m3 (144 mg/m3-min) or to
    0.4 mg/m3 for 6 h/day, 5 days/week for 4 to 12 weeks.  This effect
    was reversible following termination of exposure.  In a host
    resistance assay in mice, exposure to concentrations of phosgene of
    0.1 mg/m3 or more for 4 h (>24 mg/m3-min) led to an increase in
    mortality from  Streptococcus zooepidemicus infection.

         No long-term exposure studies of phosgene have been reported and
    studies in dogs exposed 1-3 times/week for 12 weeks are of limited
    value for risk assessment in view of study design and a lack of dose
    response. Furthermore, available data in experimental animals are
    inadequate for the assessment of the potential reproductive,
    developmental, neurotoxic and carcinogenic effects from phosgene
    exposures.

         Phosgene exposure can result in eye and skin irritation.

    2.6  Effects on humans

         As in experimental animals, the target organ in humans is the
    lung. After acute exposure to between 4 and 800 mg/m3, Habers Law
    (CxT) is applicable.  The cascade of events after acute inhalation
    exposure in humans is similar to that in experimental animals.  Their
    occurrence is dose-related and results in pulmonary oedema and death
    in humans at levels exceeding 120 mg/m3-min.  Three distinct
    clinico-pathological phases can be recognized, namely: pain in the
    eyes and throat and tightness of the chest, often with shortness of
    breath, wheezing and coughing; a latent phase which is often
    asymptomatic and lasts normally up to 24 h depending upon the
    concentration and duration of exposure; and the final phase of
    pulmonary oedema.  In one study pulmonary oedema occurred after a
    latent phase of 48 h.

         Populations exposed to phosgene after industrial accidents have
    reported a wide variety of symptoms, including headache, nausea,
    cough, dyspnoea, fatigue, pharyngeal pain, chest tightness and pain,
    intense pain in the eye, and severe lacrimation.  After short-term
    exposures throat irritation occurs at levels of 12 mg/m3 and eye
    irritation is noted at 16 mg/m3.  It has been calculated that doses
    below 100 mg/m3 will result in no permanent adverse effects, whereas
    pulmonary oedema results from doses above 600 mg/m3-min.  Death has
    been recorded at doses above 400 mg/m3-min, and exposure for several
    hours at concentrations at or below the odour threshold of 6 mg/m3
    may result in severe tissue damage and death.  Thus, the odour
    threshold for phosgene is an unacceptable parameter for early warning.

         A review of the health status of workers recovering from acute
    phosgene exposures has shown no adverse effects, but full recovery may
    take several months.

         Available data on human health effects associated with chronic
    exposure to phosgene are extremely limited.  Epidemiological studies
    of phosgene production workers and uranium workers reported no adverse
    effects on human health.  However these investigations were limited by
    small numbers of exposed workers, lack of reliable quantitative
    information on exposure to phosgene, concomitant exposure to other
    substances, limited number of end-points examined and limited
    reporting of relevant information.

    3. CONCLUSIONS

    3.1  Human health

         Phosgene is an extremely reactive chemical. It has the potential
    to cause adverse effects in humans, the primary target organ being the
    respiratory system.

         Acute severe phosgene exposure primarily causes respira-tory
    disease (pulmonary oedema) and may result in death. Survivors may
    recover completely provided they receive proper medical support.

         Accidental industrial releases can cause health problems to
    workers and the nearby community.

         Occupational exposures in closed-system industrial facilities
    manufacturing and/or using phosgene and having good industrial hygiene
    practices have not shown demonstrable risk to the workers.

         Present levels of exposure to phosgene in the general population
    are extremely low (1.6 to 2.6 g/24 h) and do not pose a health risk.
    However, individuals working with chlorinated solvents such as tri-
    and tetrachloro-ethylene and methylene chloride or who are exposed to
    chlorinated hydro-carbon polymers (e.g., polyvinyl chloride) in
    contact with flames and/or other thermal energy sources, e.g.,
    firemen, welders, painters and people working at home with these
    materials, can be exposed to levels of phosgene known to cause adverse
    effects in humans.

         No human or animal data are available on the effects of chronic
    low-level exposure to phosgene.

         Available data are inadequate to derive a meaningful health-based
    guidance value for exposure of the general population to phosgene.
    However, recent toxicological studies in rats sub-chronically exposed
    by inhalation to low levels of phosgene (0.4 mg/m3) indicate that
    early pulmonary effects may occur at present threshold limit values.
    Therefore, consideration by appropriate authorities might be given to
    re-evaluating current occupational exposure guidelines for this
    chemical.

    3.2  Environment

         No data are available concerning adverse effects of phosgene on
    the ecosystem. However, levels of phosgene in the environment would
    not be expected to result in significant effects on aquatic or
    terrestrial biota. Owing to the very rapid release of hydrochloric
    acid, damage to plants and aquatic organisms could occur in areas
    where accidental release of phosgene occurs.

    4.  HUMAN HEALTH HAZARDS, PREVENTION AND PROTECTION, EMERGENCY
        RESPONSE

    4.1  Human health hazards, prevention and protection, first aid

         The only organs affected are skin, lung and eyes, with the lung
    being the primary target.  Only a small portion of inhaled phosgene is
    hydrolysed in the fluid films of the eyes and the upper respiratory
    passages, giving rise to immediate but transient irritative signs and
    symptoms, if the inhaled phosgene concentration is greater than
    16 mg/m3 (4 ppm).  Exposure to concentrations greater than
    600 mg/m3-min (150 ppm-min) will cause pulmonary oedema, the clinical
    signs and symptoms of which may need several hours to appear and will
    do so in a dose-dependent fashion ("clinically latent period").

         The human health hazards associated with certain types of
    exposures to phosgene, together with preventive and protective
    measures and first aid advice, are listed in the Summary of Chemical
    Safety Information in section 6.

    4.1.1  Advice to physicians

    4.1.1.1  Symptoms of poisoning

         Phosgene is an extremely strong respiratory tract irritant. 
    Alveolar toxic oedema may become evident 1 to 24 h after exposure
    depending upon the level and duration of exposure.  Signs and symptoms
    of this type of pulmonary oedema are rapid shallow breathing,
    shortness of breath, cough with production of frothy fluid, pulmonary
    shadows on the X-ray, and reduction in vital capacity and respiratory
    volume.

         Eye and skin irritation occurs after severe exposure
    (> 12 mg/m3).  Serious skin injury from such exposures is unlikely.

         Dermal burns can develop after exposure to the liquidified
    material.

    4.1.1.2  Medical treatment

         Immediate termination of exposure is essential and the patient
    should be removed to fresh air.

         After exposure to liquid phosgene, contaminated clothing should
    be removed and disposed of.  Exposed skin should be washed with large
    amounts of soap and water.  If there was eye contact, the eyes should
    be flushed with copious amounts of water for at least 15 min.

         After exposure by inhalation, physical exertion should be avoided
    and strict bed rest enforced for between 24 and 72 h, particularly if
    the exposure dose was unknown or above 100 mg/m3-min (25 ppm-min). 
    Chest radiographs, arterial blood gases and other diagnostic
    procedures are indicated to evaluate the presence of pulmonary oedema,
    the primary danger after inhalation exposure to phosgene.  When
    pulmonary oedema is present the patient should be managed as though
    respiratory failure was impending.  Deep breathing is recommended to
    remove additional phosgene from the lung.

         No specific antidote is known.  Hexamethylenetetramine is
    effective only if administered prior to phosgene inhalation. 
    Pulmonary oedema should be managed with positive pressure oxygen
    ventilation and the early intravenous administration of steroids
    (e.g., 1 g of methyl-prednisolone) may be beneficial.  Additionally,
    the administration of such -adrenergic agonists as terbutaline,
    albuteral, isoetharine and metaproterenol (as aerosols or nebulizers)
    seems to be effective to correct bronchospasms.  In severe cases
    aminophylline should be considered to control bronchoconstriction and
    relieve vasoconstriction.  Most other drugs are ineffective and may
    even be harmful, e.g., atropine, epinephrine, cardiac glycosides,
    sedatives and expectorants.  Antibiotic treatment might become
    necessary if secondary infectious pneumonitis occurs.

         Symptomatic therapy may become necessary, and patients should be
    followed and surveyed until pulmonary function has normalized and the
    patient fully recovered.  Depending upon the exposure concentration
    and time, full recovery can take several months.

    4.1.2  Health surveillance advice

         Workers having the potential for exposure to phosgene should be
    supplied with personal monitors.  Workplace controls should be
    initiated to lower the levels of phosgene to levels not detectable by
    paper strip monitors (about 0.4 to 0.5 mg/m3).  Preferably,
    monitoring devices must sound an alarm or otherwise warn workers when
    a concentration of 0.8 mg/m3 is reached.

         Preplacement and periodic medical examinations should be given to
    all workers with the potential to be exposed to phosgene.  These
    should include chest radiographs and pulmonary function tests.

    4.2  Explosion and fire hazards

         Phosgene is non-flammable.  However, the presence of water or
    high temperature can cause containers of phosgene to rupture.  This
    can release both liquid and gaseous phosgene, as well as toxic thermal
    degradation and reaction products such as hydrochloric acid, chlorine
    and carbon monoxide.

         All phosgene-containing vessels should be removed from the
    vicinity of a fire, if this can be done without risk, and kept below
    50 C by water cooling unless phosgene is leaking from a cylinder.  
    Do not allow water to enter the containers.  Fire-fighters must wear
    protective clothing and a self-contained breathing apparatus.  For
    small fires use dry chemical or carbon dioxide.  Use water spray, fog
    or foam for larger fires.

    4.3  Storage

         Phosgene should be stored in appropriately labelled corrosion-
    resistant steel cylinders that conform to rigid safety-design
    specifications for this chemical.  Storage should be in cool, dry, and
    well-ventilated fire-proof rooms isolated from the work area.  Ambient
    air monitoring should be provided and ventilation should be located at
    floor level.  Protect cylinders against physical damage, and secure to
    prevent falling or rolling.  Because phosgene reacts with water, great
    care should be taken to prevent contamination with water, since this
    could lead to increased pressure in the tanks with possible resultant
    rupture.  Phosgene containers should be frequently inspected for
    damage and prolonged storage should be avoided.

    4.4  Transport

         Phosgene may be transported in appropriately designed cylinders
    as a compressed gas.  Transport must comply with guidelines from
    international bodies, as well as regulations at the national and local
    levels regarding the movement of hazardous materials.  It should be in
    rigid corrosion-resistant steel containers regularly inspected for
    damage and conforming to design specifications specific for phosgene. 
    All containers must be well-labelled and protected from damage in
    shipment.  Acceptable modes of transportation are road and water.

    4.5  Spillage and disposal

    4.5.1  Spillage

         Skin contact with liquid and inhalation of gaseous phosgene
    should be avoided.  Non-essential people should be kept away and the
    area isolated. People in the immediate vicinity should be moved to an
    area upwind until the gas has dispersed.  Those involved in clean-up
    operations of large spills without fire should be provided with fully
    encapsulated protective clothing, and self-contained breathing
    apparatus.  Fire-fighter's normal protective clothing will provide
    limited protection for short-term exposures only.  For large spills a
    dyke should be made well ahead of liquid spill for later disposal.
    Water should not be allowed to enter the area inside the dyke or to
    enter any containers.

         Liquid spills can be covered with sodium hydrogen carbonate or an
    equal mixture of soda ash and slake lime or crystallized urea.  Water
    from an atomizer can then be added cautiously and the mixture
    transferred to a large volume of water.  Gas spills can be mitigated
    by gaseous ammonia, aqueous ammonia or an ammonia steam curtain or
    sprays.

         There should be a holding area beneath any storage or handling
    installation that can contain a liquid spill.  This should have an
    impermeable flexible membrane liner and must already contain lime,
    limestone, sodium hydrogen carbonate, urea or any other suitable
    neutralizing absorbent, sufficient to eliminate the spill.

    4.5.2  Disposal

         Dilute aqueous phosgene wastes can best be handled through
    caustic scrubbing in packed columns or by scrubbing in towers with
    activated carbon and water.  Phosgene or aqueous phosgene wastes
    should never be disposed of into sewers without prior alkaline
    neutralization.

         Phosgene should not be introduced into an incinerator.  However,
    if a product containing, or capable of producing phosgene is entering
    an incinerator, then there must be an adequate scrubbing installation
    to remove phosgene and/or HCl from the issuing gases.  These
    techniques must conform to all local and national regulations.

         Welding and disposal of tanks and equipment used to handle
    phosgene should take place only after all residual phosgene has been
    purged from these materials.

    4.6  Other protective measures

         Paint removers and non-flammable dry cleaning solvents (e.g.,
    carbon tetrachloride, chloroform, tri- and tetrachloroethylene and
    methylene chloride) should never be used in closed areas in the
    presence of fire or heaters of any kind since they can decompose to
    phosgene.  Welding or heat-treating vessels or equipment that may have
    contained such materials should be avoided until they have been purged
    of all residual chemical.

         Contaminated protective clothing should not be taken home.  It
    must be decontaminated on site with care to avoid direct contact with
    cleaning staff or other employees.  It should be segregated in the
    workplace in such a manner so as to avoid direct contact with cleaning
    staff or other employees.

    5.  HAZARDS FOR THE ENVIRONMENT AND THEIR PREVENTION

         Phosgene hydrolyses in the presence of water or after adsorption
    onto soil and vegetation to form hydrochloric acid and carbon dioxide. 
    However, plants can be killed by phosgene or hydrochloric acid after
    exposure to spills or high levels of industrial emissions.  Aquatic
    organisms are at little risk from phosgene levels normally found in
    industrial effluents.  However, concentrations of hydrochloric acid
    arising from spills will be high enough to alter significantly the pH
    of the water and to alter aquatic life cycles.  The physico-chemical
    properties of phosgene preclude its bioaccumulation or
    biomagnification.

    6.  SUMMARY OF CHEMICAL SAFETY INFORMATION

         The material in this section is based on the IPCS International
    Chemical Safety Card number 7.  This card should be easily available
    to all health workers concerned with, and users of, phosgene.  It
    should be displayed at, or near, entrances to areas where there is
    potential exposure to phosgene and on processing equipment and
    containers.  The card should be translated into the appropriate
    language(s).  All persons potentially exposed to the chemical should
    also have the instructions on the chemical safety card clearly
    explained.

        SUMMARY OF CHEMICAL SAFETY INFORMATION
                                                                                                                                                

                                                      PHOSGENE
                                                      COC12
                                                                                                                                                

    PHYSICAL PROPERTIES                                                                            OTHER CHARACTERISTICS
                                                                                                                                                

    Relative molecular mass                           98.9                                         Colourless gas, or colourless compressed
    Melting point (C)                                -127.8                                       liquefied gas with characteristic odour.
    Boiling point (C)                                7.5                                          However, the odour warning when the
    Relative density of the liquid (water=1)          1.4                                          exposure limit value is exceeded is
    Solubility in water                               Reaction                                     insufficient. The vapour is heavier than air
    Vapour pressure, kPa at 20 C                     161.6                                        and may travel along the ground.
    Relative vapour density (air=1)                   3.42                                         Decomposes above 300 C to corrosive and
                                                                                                   toxic gases (chlorine, hydrogen chloride, and
                                                                                                   carbon monoxide).  Reacts rapidly with
                                                                                                   ammonia, amines, aluminium and many
                                                                                                   other chemicals; in some cases, forming
                                                                                                   shock-sensitive products                           
                                                                                                                                                

    ACUTE HAZARDS/SYMPTOMS                            PREVENTION AND PROTECTION                    FIRST AID/FIRE-FIGHTING
                                                                                                                                                

    SKIN: Corrosive redness, skin burns,              Cold-insulating gloves, protective clothing  ON FROSTBITE: rinse with plenty of
    pain, in cases of frostbite from liquid;                                                       water, do NOT remove clothes, rinse skin
    blisters                                                                                       with plenty of water or shower, and
                                                                                                   immediately refer for medical attention

    EYES: Redness, pain, blurred vision               Face shield or eye protection in             First rinse with plenty of water for several
                                                      combination with breathing protection        minutes (remove contact lenses if easily
                                                                                                   possible), then take to a doctor
                                                                                                                                                

    SUMMARY OF CHEMICAL SAFETY INFORMATION (con't)
                                                                                                                                                

    ACUTE HAZARDS/SYMPTOMS                            PREVENTION AND PROTECTION                    FIRST AID/FIRE-FIGHTING
                                                                                                                                                

    INHALATION: Pungent cough, laboured               Ventilation, local exhaust, or breathing     Fresh air, complete rest, half-upright
    breathing, shortness or breath, sore throat       protection.  Wear indicator badges           position, artificial respiration if indicated
                                                                                                   and refer for medical attention as soon as
                                                                                                   possible. The symptoms of lung oedema often
                                                                                                   do not become manifest for up to 24 h and
                                                                                                   they are aggravated by physical effort. Rest
                                                                                                   and medical observation are therefore
                                                                                                   essential.  Immediate administration of an
                                                                                                   appropriate spray, by a doctor or a person
                                                                                                   authorized by him/her, should be considered
                                                                                                                                                

    SPILLAGE                                          STORAGE                                      FIRE AND EXPLOSION
                                                                                                                                                

    Evacuate danger area, create an aqueous           Fire-proof if in building, isolated from     No open flames or other sources of high
    ammonia spray curtain to neutralize gas           work area and other chemicals on a           temperatures.  Phosgene is non-flammable
    cloud, consult an expert, ventilation;            perforated floor over disposal tank          and non-oxidative but cylinders may rupture
    cautiously neutralize spilled liquid with         containing soda ash/ slaked lime in cool     if heated.  Therefore, in case of fire in
    sodium hydrogen carbonate or an equal             dry location with ventilation along the      surroundings remove all phosgene-containing
    mixture of soda ash and slaked lime or            floor. Ambient air monitoring should         vessels.  If not possible, keep cylinders
    crystallized urea (extra personal                 be provided                                  cool by spraying with water.  On flames use
    protection: complete protective clothing                                                       foam, powder or carbon dioxide
    including self-contained breathing
    apparatus)
                                                                                                                                                
        7.  CURRENT REGULATIONS, GUIDELINES AND STANDARDS

         The information in this section has been extracted from the
    International Register of Potentially Toxic Chemicals (IRPTC) legal
    file and other UN sources.   It is a representative but non-exhaustive
    overview of current regulations, guidelines and standards. 
    Regulations and guidelines about chemicals can be fully understood
    only within the framework of a country's legislation, and are always
    subject to change.  Therefore, they should always be verified with the
    appropriate authorities.

    7.1  Occupational exposure limit values

         Some examples of exposure limit values in several countries are
    given in the table.

    7.2  Labelling, packing and transport

         Internationally, transportation of phosgene is limited on
    passenger-carrying ships and is forbidden on passenger and cargo
    aircraft.  Some countries extend this to passenger railcars.

         Phosgene is classed as an IMO Class 2 hazard requiring labelling
    with UN number 1076 and labels showing it to be a poisonous gas and
    corrosive.

    
    CURRENT REGULATIONS, GUIDELINES AND STANDARDS
                                                                                                        

    Occupational Exposure Limit Valuesa
                                                                                                        

    Country/organization     Exposure limit descriptionb              Value         Effective datec
                                                                     (mg/m3)
                                                                                                        

    Australia                Time-weighted average (TWA)                0.4              1990
    Belgium                  Time-weighted average (TWA)                0.4              1991R
    Czech Republic           Time-weighted average (TWA)                0.5              1985
    Denmark                  Short-term exposure limit (STEL)           0.2              1991R
    Finland                  Short-term exposure limit (STEL)           0.2              1991R
    France                   Short-term exposure limit (STEL)           0.4              1991R
    Germany                  Time-weighted average (TWA)                0.4              1994
    Japan                    Time-weighted average (TWA)                0.4              1991R
    Poland                   Time-weighted average (TWA)                0.5              1991R
    United Kingdom           Time-weighted average (TWA)                0.4              1991R
    USA: ACGIH               Time-weighted average (TWA)                0.4              1995
    USA: NIOSH/OSHA          Time-weighted average (TWA)                0.4              1990
    USSR                     Time-weighted average (TWA)                0.4              1991R
                             Short-term exposure limit (STEL)           0.5              1991R
                                                                                                        

    a    From: ILO (1991) and national lists.
    b    TWA = time-weighted average (8 h or 10 h shift); STEL = short-term (15 min TWA) exposure
         limit not to be exceeded at any time during a shift.
    c    Where effective date is not reported, the date given is for the reference publication and
         marked 1991R.
    
    BIBLIOGRAPHY

    Borak J (1991) Phosgene toxicity: review and update. CEM Report,
    5: 19-21.

    Clayton GD & Clayton FE (1994) Patty's industrial hygiene and
    toxicology, 4th ed. New York, Chichester, John Wiley and Sons.

    Diller WF (1985a) Therapeutic strategy in phosgene poisoning. Toxicol.
    Ind Health, 1: 93-99.

    Diller WF (1985b) Late sequelae after phosgene poisoning: a literature
    review.  Toxicol Ind Health, 1: 129-136.

    HSE (1995) Phosgene. In: Critical document summaries: Synopses of the
    data used in setting occupational exposure limits. London, Health and
    Safety Executive, pp 24-25 (EH 64 1995 Supplement).

    HSDB (1996) Hazardous substances data bank. Bethesda, Maryland,
    National Library of Medicine (CD-ROM version - Micromedex, Inc.,
    Denver).

    ILO (1983) In: Parmeggiani L ed., Encyclopedia of occupational health
    and safety, 3rd revis. ed., Geneva, International Labour Office,
    Vol. 2.

    IPCS (1997) Environmental Health Criteria 193: Phosgene. Geneva, World
    Health Organization, International Programme on Chemical Safety.

    NIOSH (1990) Pocket guide to chemical hazards. Cincinnati, Ohio,
    National Institute for Occupational Safety and Health, (DHHS (NIOSH)
    Publication No. 90-117).

    SCHNEIDER W & DILLER W (1989) Phosgene. In: Encyclopedia of industrial
    chemicals, 5th ed. Weinheim, Germany, VCH Verlag, vol. A19,
    pp 411-420.






    See Also:
       Toxicological Abbreviations
       Phosgene (EHC 193, 1997)
       Phosgene (ICSC)
       Phosgene (PIM 419)