Health and Safety Guide No. 15






    This is a companion volume to Environmental Health Criteria 56:
    Propylene Oxide

    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)

    ISBN 92 4 154338 8
    ISSN 0259 - 7268

    (c) World Health Organization 1988

    Publications of the World Health Organization enjoy copyright
    protection in accordance with the provisions of Protocol 2 of the
    Universal Copyright Convention. For rights of reproduction or
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    should be made to the Office of Publications, World Health
    Organization, Geneva, Switzerland. The World Health Organization
    welcomes such applications.

    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



        1.1. Identity
        1.2. Physical and chemical properties
        1.3. Composition
        1.4. Production and uses

        2.1. Human exposure
        2.2. Fate in the environment
        2.3. Uptake, metabolism, and excretion
        2.4. Effects on organisms in the environment
        2.5. Effects on animals
        2.6. Effects on human beings


        4.1. Main human health hazards, prevention and protection, first aid
            4.1.1. Advice to physicians
            4.1.2. Health surveillance advice
        4.2. Explosion and fire hazards
            4.2.1. Explosion hazards
            4.2.2. Fire hazards
       Fire-extinguishing agents
        4.3. Storage
        4.4. Transport
        4.5. Spillage and disposal
            4.5.1. Spillage
            4.5.2. Disposal



        7.1. Previous evaluations by international bodies
        7.2. Exposure limit values
        7.3. Specific restrictions
        7.4. Labelling, packaging, and transport
        7.5. Waste disposal
        7.6. Other measures


    The Environmental Health Criteria (EHC) documents 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 an International Chemical
    Safety Card 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, it is inevitable that
    sections 1 and 2 contain 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 Manager
            International Programme on Chemical Safety
            Division of Environmental Health
            World Health Organization
            1211 Geneva 27



    1.1 Identity

    Common name:                Propylene oxide

    Chemical formula:           C3H6O

    Chemical structure:

                                    H     O
                                    '   /   \
                                H - C - C - C - H
                                    '   '   '
                                    H   H   H

    Common synonyms:            1,2-epoxypropane, methyl ethylene oxide,
                                methyl oxirane, propene oxide, propylene
                                epoxide, 1,2-propylene oxide

    CAS registry number:        75-56-9

    RTECS registry number:      TZ2975000

    UN number:                  1280

    Conversion factors:         1 ppm = 2.37 mg/m3
                                1 mg/m3 = 0.42 ppm at
                                25C and 101.3 kPa (760 mmHg)

    1.2 Physical and Chemical Properties

    Propylene oxide is a colourless, highly volatile liquid at room
    temperature and normal atmospheric pressure. It has an ethereal
    odour with reported odour thresholds of 20 mg/m3 for perception
    and 80-470 mg/m3 for recognition.

    The liquid is highly flammable and the vapour forms an explosive
    mixture with air. Propylene oxide may polymerize violently. It is
    very reactive, particularly with chlorine, ammonia, strong oxidizing
    agents, and acids. Some physical and chemical properties of
    propylene oxide are listed on the International Chemical Safety Card
    (pp. 20-23).

    1.3 Composition

    Common impurities that may be present in small amounts include
    water, acetic acid, chloride, and aldehydes. Small amounts of
    monochloroacetone, 1,2-dichloro-3-propanol, and propylene dichloride
    can occur in the end product, when propylene oxide is manufactured
    by the chlorohydrin process.

    1.4 Production and Uses

    World production of propylene oxide exceeds 2 million tonnes per
    year. Large volume producers are found in Japan, the USA, and
    Western Europe. Most of the compound is used as a chemical
    intermediate. Small amounts are used for the sterilization of
    medical equipment and for the fumigation of foodstuffs.


    2.1 Human Exposure

    The main route of human exposure is through inhalation at the work
    place. No published data have been found on ambient levels at a
    distance from point sources. Eight-hour time-weighted average
    occupational exposure levels are normally below 5 mg/m3, however,
    peak exposures of up to 9000 mg/m3 have been recorded. Data are
    insufficient to estimate the levels of exposure to propylene oxide
    through residues in food after fumigation and sterilization. The
    main conversion products in foodstuffs are chloropropanols and
    1,2-propanediol, which are more persistent than the parent compound.
    Analysis of fumigated foodstuffs revealed that chloropropanols and
    1,2-propanediol were present at levels ranging from 4 to 47 mg/kg
    and 29 to 2000 mg/kg, respectively. However, in pure fats, where
    degradation is minimal, levels of propylene oxide of over 4000mg/kg
    have been determined. Levels of up to 6260 mg/kg have been found in
    wrapping materials.

    2.2 Fate in the Environment

    Propylene oxide enters the environment mainly through evaporation
    and in vented gases during production, handling, storage, transport,
    and use. The compound is removed from the atmosphere by slow
    oxidation and by rain washout.

    It is highly soluble in water, but is likely to evaporate to a great
    extent. In neutral fresh water, propylene oxide is converted to
    1,2-propanediol and, in marine waters, to halopropanols, but, even
    in the presence of micro-organisms, these processes are slow.
    Because of its limited lipid solubility, propylene oxide is unlikely
    to bioaccumulate.

    2.3 Uptake, Metabolism, and Excretion

    Inhaled propylene oxide is readily absorbed, distributed throughout
    the body, and rapidly metabolized. The half-life in the rat has been
    estimated to be 40 min. Data are not available on skin absorption.
    From in vitro studies, it would appear that propylene oxide is
    metabolized by glutathione epoxide transferase to S-(2-hydroxy-
    1-propyl)glutathione. It is converted to 1,2-propanediol by epoxide
    hydrolase and non-enzymic hydrolysis, but both of these reactions
    are slow. The diol can be oxidized to lactic and pyruvic acid.

    2.4 Effects on Organisms in the Environment

    The toxicity of propylene oxide for aquatic organisms is low.
    Concentrations lethal for half the number of fish in populations
    tested for 1-4 days were approximately 90 mg/litre (LC50) or
    higher. The probability of adverse effects on the aquatic
    environment is considered to be low.

    2.5 Effects on Animals

    Single oral doses of 520-1140 mg/kg body weight (LD50) or vapour
    concentrations of 9500 mg/m3 (LC50) for 4 h have been shown to be
    lethal for half the number of exposed rats. The compound is thus
    slightly toxic in acute exposures, according to the scale of Hodge &
    Sterner. Damage to the stomach mucosa and liver was observed after
    lethal oral exposure, and severe eye and nose irritation, laboured
    breathing, and central nervous system depression were observed after
    lethal vapour exposure. Dogs exposed through inhalation, once for
    4h, to a concentration of 3230-5880 mg/m3 showed salivation,
    lachrymation, nasal discharge, and vomiting. Deaths were observed at
    4750-5880 mg/m3, but not at 3230 mg/m3.

    When various animal species were exposed to propylene oxide vapour,
    for 7 h per day, 5 days per week, for 112-218 days, at
    concentrations of 0, 240, 460, or 1080 mg/m3, rabbits and monkeys
    did not show any adverse effects on appearance, mortality, growth,
    and histopathology of internal organs. Rats and guinea-pigs showed
    irritation of the respiratory passages and histological lung damage
    at 1080 mg/m3. An increase in lung weight was observed in female
    guinea-pigs at concentrations of 460 mg/m3 or more. No effects
    were observed in any species at a concentration of 240 mg/m3. A
    concentration of 3400 mg/m3 administered over 2 weeks, for 6 h per
    day, 5 days a week, resulted in dyspnoea and death in rats. In the
    same study, mice showed dyspnoea at 460 and 1150 mg/m3. Reduced
    activity was observed in both species, and irregular limb movement
    was seen in rats.

    Rats and mice exposed for 2 years showed dose-related increased
    incidences of inflammatory and proliferative lesions of the nasal
    epithelium at an exposure level of 470 mg/m3. In rats, the
    inflammatory lesions and hyperplasia were also observed at an
    exposure level of 240 mg/m3, but not at 70 mg/m3.

    Depression of the central nervous system, the severity of which
    increased with increasing level and length of exposure, was observed
    when rats and mice were exposed through inhalation to single high
    concentrations of propylene oxide.

    An aqueous solution of propylene oxide (100 or 200 g/litre) was
    irritating to rabbit skin, when applied under occlusive cover.

    Propylene oxide administered via inhalation for 2 years produced
    ovarian atrophy in mice at 940 mg/m3. Testicular atrophy was found
    at 240 and 720 mg/m3 in rats.

    No sperm head abnormalities were detected in mice after exposure to
    720 mg propylene oxide/m3 for 7 h/day, over 5 days, or in
    cynomolgus monkeys exposed to 240 or 710 mg/m3 for 7 h/day and 5
    days/week, over 2 years, but sperm count and motility were reduced,
    and sperm drive range (time to traverse a linear path) increased in
    the monkeys. Reduced sperm motility and damage to spermatocytes were
    observed in male rats treated with an oral LD50 (520 mg/kg body
    weight) dose. Reduced fertility was observed when these males were
    mated with normal females between 2 and 10 weeks after exposure.

    Reduced fetal ossification of vertebrae and ribs and wavy ribs were
    observed when pregnant Sprague Dawley rats were exposed to 1190 mg
    propylene oxide/m3, for 7 h/day, on days 1-16 of gestation. When
    rats were additionally exposed for 3 weeks before mating, the
    numbers of corpora lutea, implantations per dam, and live fetuses
    were decreased. No teratogenic or fetotoxic effects were found in
    New Zealand rabbits exposed to propylene oxide at 1190 mg/m3.

    Propylene oxide is an alkylating agent. It is mutagenic in micro-
    organisms and insects and produces DNA damage, mutations, and
    chromosomal aberrations in mammalian cells in vitro. It produced
    micronuclei in mouse erythrocytes after parenteral injection of 2
    doses of 300 mg/kg body weight, but not after oral exposure. No
    chromosomal aberrations or sister chromatid exchanges occurred in
    monkeys exposed through inhalation to 237 or 717 mg propylene
    oxide/m3, for 7 h per day, 5 days per week, for 2 years. No
    dominant lethal effects were observed in rats or mice following
    inhalation or oral exposure, respectively.

    In long-term studies on the carcinogenicity of propylene oxide in
    rats and mice, malignant tumours were mainly observed at the site of
    entry into the body and included: squamous cell carcinomas of the
    forestomach in rats administered oral doses of 15 or 60 mg/kg body
    weight; local sarcomas in mice at subcutaneous doses of 1 and 2.5 mg
    per mouse; nasal adenomas in rats exposed through inhalation at 940
    or 717 mg/m3 (but not at 470 mg/m3); and mainly nasal
    haemangiomas and haemangiosarcomas in mice at 940 mg/m3. At the
    dose levels at which these tumours were induced, propylene oxide
    produced localized tissue damage. In rats, the incidences of both
    phaeochromocytomas in the adrenals and peritoneal mesotheliomas
    increased following inhalation exposure to propylene oxide. It also
    induced an increase in the incidence of mammary adenocarcinomas in
    female rats following inhalation exposure at 940 mg/m3.

    2.6 Effects on Human Beings

    Corneal and conjunctival damage and allergic contact dermatitis have
    been reported following accidental exposure to propylene oxide

    Adequate data on chromosomal effects in human beings are not

    Adequate epidemiological studies on cancer incidence in exposed
    populations have not been carried out.

    Taking into account the available data, i.e., the alkylating nature
    of propylene oxide, the formation of DNA adducts, the positive
    responses in both  in vitro and  in vivo mutagenesis assays, the
    carcinogenic effects on animals, predominantly at the sites of entry
    into the body, and the absence of adequate data on cancer in human
    beings, propylene oxide should be considered as a probable human
    carcinogen, and levels in the environment should be kept as low as


    On the basis of available data, propylene oxide should be
    considered, for practical purposes, as a probable human carcinogen,
    and exposure should be kept as low as possible.

    The predominant long-term effects of inhalation may include
    irritation of the nose and the other respiratory passages, lung
    damage, and dyspnoea. Propylene oxide exhibits fetotoxicity in rats
    and affects the spermatogenic function in monkeys. Common effects
    following exposures to high vapour concentrations include irritation
    of the eyes and respiratory tract, nasal discharge, dyspnoea, and
    central nervous system depression. Damage to stomach mucosa and the
    liver were observed after high oral exposures. A solution of
    propylene oxide in water is irritating to the skin and may produce
    allergic contact dermatitis.

    The risk for the health of the general population from exposure to
    ambient air concentrations of propylene oxide is likely to be


    4.1 Main Human Health Hazards, Prevention and Protection, First Aid

    The human health hazards associated with certain types of exposure
    to propylene oxide, preventive and protective measures, and first
    aid recommendations are listed in the International Chemical Safety
    Card on pp. 20-23.

    4.1.1 Advice to Physicians

    No specific antidote is known. Treat symptomatically. If skin
    sensitization has developed because of exposure to propylene oxide,
    further exposure should not be allowed. Be aware of the possibility
    of delayed pulmonary oedema.

    4.1.2 Health Surveillance Advice

    Human beings potentially exposed to propylene oxide should undergo
    periodic medical examination with particular emphasis given to the
    respiratory tract, the reproductive system, skin, and eyes.
    Physicians should be aware of the fact that propylene oxide is
    carcinogenic in experimental animals and that it should be regarded,
    for practical purposes, as if it represented a carcinogenic risk for
    human beings.

    Exposure to propylene oxide should be checked regularly by general
    and/or personal monitoring.

    4.2 Explosion and Fire Hazards

    4.2.1 Explosion hazards

    Propylene oxide-air mixtures containing 2-37% by volume of propylene
    oxide may be explosive at or above -37C and can be ignited by
    sources of heat or ignition. The vapour, which is heavier than air,
    may travel along the ground and be ignited from a distance.

    The compound may polymerize violently. It reacts violently with many
    compounds including chlorine and other oxidizing agents, ammonia,
    acids, and chlorosulfonic acid.

    4.2.2 Fire hazards

    Propylene oxide is a highly flammable liquid. Prevention

    Use closed systems, ventilation, explosion-proof electrical
    equipment and lighting, and spark-proof hand tools. Do not use
    propylene oxide near sources of heat or ignition. Do not smoke. Do

    not use compressed air for filling, discharging, or handling. Avoid
    contact between the compound and incompatible materials (section

    In the case of fire, shut off the supply. If this is impossible and
    there is no risk to the surroundings, let the fire burn itself out.
    Firefighters should be equipped with self-contained breathing
    apparatus, eye protection, and full protective clothing. Fire-extinguishing agents

    Use powder, alcohol-resistant foam, large amounts of water, halons,
    or carbon dioxide.

    4.3 Storage

    Propylene oxide should be well-labelled and stored in a cool,
    fire-roof, well-ventilated room. Keep away from any sources of
    ignition or heat, and incompatible materials (section 4.2.1). It
    should not be stored where food can become contaminated.

    4.4 Transport

    In case of accident, stop the engine. Remove all sources of
    ignition. Keep bystanders at a distance and mark the roads. Keep
    upwind. Evacuate the area endangered by poison gas. Wear full
    protective clothing and self-contained breathing apparatus. In case
    of spillage or fire, use the methods advised in sections 4.5 and
    4.2, respectively. In case of poisoning, follow the advice in
    section 4.1. Notify the police and the fire brigade immediately.

    4.5 Spillage and Disposal

    4.5.1 Spillage

    Remove all ignition sources and evacuate the danger area; collect
    leaking liquid in sealable containers; absorb spilled liquid in sand
    or other inert absorbent and remove to a safe place. Ensure personal
    protection by use of self-contained breathing apparatus and full
    protective clothing.

    4.5.2 Disposal

    Discharge concentrated liquid wastes that do not contain peroxides,
    at a controlled rate, near a pilot flame. For concentrated liquid
    wastes that do contain peroxides, perforate the container from a
    safe distance and burn the waste in an open area. Open burning and
    evaporation are recommended for small amounts. Incineration may be
    difficult in view of the high volatility of the compound.


    Propylene oxide will evaporate from water. Degradation in the
    atmosphere and in water is slow. Bioaccumulation of propylene oxide
    and its conversion products is unlikely.

    The toxicity of propylene oxide for aquatic organisms is low. The
    probability of an adverse impact on the aquatic environment is
    considered low.

    Contamination of soil, water, and the atmosphere can be avoided by
    proper methods of storage, transport, handling, and waste disposal.
    In the case of spillage, apply the methods recommended in section


     This card should be easily available to all health workers
     concerned with, and users of, propylene oxide. It should be
     displayed at, or near, entrances to areas where there is potential
     exposure to propylene oxide, 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.

     Space is available on the card for insertion of the National
     Occupational Exposure Limit, the address and telephone number of
     the National Poison Control Centre, and for local trade names. 


    (PO, 1,2-epoxypropane, methyl oxirane, propene oxide)


    PHYSICAL PROPERTIES                                      OTHER CHARACTERISTICS

    Relative molecular mass             58.08               Colourless liquid with ethereal odour; the vapour is
    Appearance                          colourless liquid   heavier than air, may travel along the ground and be
    Odour                               ethereal            ignited from a distance; the liquid may polymerize
    Odour perception threshold          20 mg/m3            violently; propylene oxide reacts violently with
    Melting point (C)                  -112.1              many compounds including chlorine and other oxidizing
    Boiling point (C)                  37.8                agents, ammonia, and chlorosulfonic acid; it
    Solubility in water (20C) (g/litre)                    405can induce adverse effects well below the odour
    Density (20C)                      0.83 g/ml           threshold
    Relative vapour density             2
    Vapour pressure (20C)              59 kPa
    Flash point (open cup)              -37C
    Flammable (explosive) limits (%)    2-37 %
    log  n-octanol/water partition
      coefficient                       -0.13



    SKIN: Severe irritation by           Wear clean protective impervious        Remove contaminated clothing and shoes
    solutions in water                   gloves and boots, and clean             immediately; rinse with water for at least
                                         impermeable body-covering clothing      15 min; seek medical attention

    EYES: Severe irritation by           Wear safety face shield or eye          Rinse opened eyes with water for
    vapour and aqueous solutions         protection in combination with          at least 15 min; seek medical attention
                                         breathing protection

    INHALATION: Irritation of            Use explosion-proof general or          Remove victim to fresh air; keep victim
    respiratory tract; dyspnoea;         exhaust ventilation and, for            quiet and warm; if breathing has stopped,
    central nervous system depression    non-routine activities, use a           apply artificial respiration; transport
                                         self-contained breathing apparatus      to hospital

    INGESTION: Irritation of             Do not eat, drink, or smoke during      Rinse mouth; give plenty of water to
    stomach; effects on liver;           work                                    drink; do not induce vomiting; 
    abdominal pain                                                               transport to hospital

    REPEATED EXPOSURE: Probable          Exposure should be kept as low as
    human mutagen and carcinogen;        feasible
    may pose a reproductive hazard 

    ENVIRONMENT: low toxicity            Use proper methods of storage,
    to aquatic life                      transport, waste disposal and
                                         handling of spills (see below)


    SPILLAGE                                                                     STORAGEFIRE AND EXPLOSION

    Remove all ignition sources;         Store in a cool, well-labelled,         Flammable; vapour-air mixtures may be
    evacuate area; collect               fire-proof, well-ventilated room;       explosive; use closed systems, ventilation,
    leaking liquid in sealable           store away from foodstuffs              and explosion-proof equipment; do
    containers; absorb spilled liquid    and incompatible materials              not use compressed air for filling,
    in sand or other inert                                                       discharging, or handling; no sources of
    absorbent; ensure personal                                                   ignition or heat; extinguish fires with
    protection by use of a self-                                                 powder, alcohol-resistant foam, lots of
    contained breathing apparatus and                                            water, halons, carbon dioxide
    full protective clothing



    Burn after ignition from a           National Occupational Exposure          UN: 1280
    safe distance; evaporation           Limit:
    in an open area
                                         National Poison Control Centre:

                                         Local trade names

    FIGURE 1


    The information given in this section has been extracted from the
    International Register of Potentially Toxic Chemicals (IRPTC) legal
    file and other United Nations sources. Its intention is to give the
    reader a representative but non-exhaustive overview of current
    regulations, guidelines, and standards.

    The reader should be aware that regulatory decisions about chemicals
    taken in a certain country can only be fully understood in the
    framework of the legislation of that country.a

    7.1 Previous Evaluations by International Bodies

    An International Agency for Research on Cancer Working Group (IARC,
    1985) evaluated the carcinogenicity of propylene oxide and concluded

    "There is sufficient evidence for the carcinogenicity of propylene
    oxide to experimental animals; there is inadequate evidence for its
    carcinogenicity to humans. It is noted that, in the absence of
    adequate data in humans, it is reasonable, for practical purposes,
    to regard chemicals for which there is sufficient evidence of
    carcinogenicity in experimental animals as if they probably
    represented a carcinogenic risk to humans." This conclusion was
    confirmed in 1987.

    7.2 Exposure Limit Values

    Some exposure limit values are given in the table on pp. 28-29.

    When no effective date appears in the IRPTC legal file, the year of
    the reference from which the data are taken is indicated by (r).

    7.3 Specific Restrictions

    In the United Kingdom, it is prohibited to undertake any activity
    that entails the use of 5 or more tons of propylene oxide on any
    site or in any pipeline, unless the health and safety executive has
    been notified at least 3 months before commencing activity.
    Specified changes in activity of this type should be re-notified as
    if it were a new activity (1983).


    a   The regulations and guidelines of all countries are subject to
        change and should always be verified with appropriate regulatory
        authorities before application.

    In the Federal Republic of Germany, handling of propylene oxide is
    prohibited or restricted for adolescents and pregnant or nursing
    women (1980).

    In Kenya, the compound is permitted as a starch-modifying agent. The
    food products in or on which it is permitted and maximum levels of
    use are listed (1982 (r)).

    In the USA, the compound may be used to modify the food additive
    "modified food starch" with certain restrictions, while residual
    propylene chlorohydrin may not exceed 5 mg/kg (1983 (r)). The
    substance is further exempted from tolerance requirements in plant,
    meat, and animal products when used according to good agricultural
    practice as an inert (or occasionally active) ingredient of
    pesticides applied to growing crops, raw agricultural products after
    harvest, or animals, for some specified purposes (1983 (r)).

    7.4 Labelling, Packaging, and Transport

    The European Community legislation requires labelling of propylene
    oxide as a dangerous substance using the symbols:

    FIGURE 2

    FIGURE 3

    The label must read:

         extremely flammable; harmful by inhalation, in contact with
         skin, and if swallowed; keep container in a well ventilated
         place; keep away from sources of ignition - no smoking; in case
         of contact with eyes, rinse immediately with plenty of water
         and seek medical advice; do not empty into drains (1983).

    The International Maritime Organisation and the United Nations
    Committee of Experts on the Transportation of Dangerous Goods
    classify propylene oxide as a flammable liquid (Hazard Class 3.1 and
    3, respectively) and a very dangerous substance for packing purposes
    (Packing Group I). Packing, transport methods, and label are
    recommended (1982 (r)). The recommended symbol on the label is: 

    FIGURE 4

    In the USA, propylene oxide, when carried in bulk, is classified as
    a "cargo of particular hazard" for the purpose of regulations
    governing handling of dangerous cargoes in or contiguous to water
    front facilities. A permit is required for handling such cargo (1983

    7.5 Waste Disposal

    In the Federal Republic of Germany, the air emissions of organic
    compounds in Class III, carcinogens, which includes propylene oxide,
    must not exceed (as the sum of all compounds in one class) a mass
    concentration of 5 mg/m3 at a mass flow of greater than 25 kg/h
    (1986 (r)).

    In the USA, the substance is designated as a hazardous substance for
    purposes of discharge (including spillage, leaking, etc.) under the
    water pollution control act. A permit is required for discharge from
    any point source into water in the USA. Under the Comprehensive
    Environmental Response, Compensation, and Liability Act of 1980
    (CERCLA), unless in compliance with a specified permit or procedure,
    owners/operators of vessels or on- or offshore facilities must
    notify the USA government (National Response Center) of any release
    of the hazardous substance in or on navigable waters, adjoining
    shorelines, the contiguous zone, or beyond the contiguous zone or to
    any other environmental media (air, land or ground water) in an
    amount equal to or more than 45.4 kg in any 24-h period (1985 (r)).

    7.6 Other Measures

    The European Community legislation concerning the major accident
    hazards of certain industrial activities foresees that the
    manufacturer must take all necessary measures to prevent accidents
    and to limit their consequences for man and the environment when
    processing propylene oxide, or when storing it in quantities equal
    to or over 50 tonnes.

    Furthermore, when propylene oxide is processed in quantities equal
    to or over 50 tonnes or is stored in quantities equal to or over
    300 tonnes, notification has to be made to the competent authorities
    including information on the substance, on the installation,
    information on possible major accident situations and emergency
    plans (1984).



    Medium      Specification      Country/            Exposure limit descriptiona                 Value            Effective
                                   organization                                                                       Date

    AIR         Occupational       Australia           Threshold limit value (TWA)                 240 mg/m3          1985 (r)

                                   Denmark             Threshold limit value (TWA)                  12 mg/m3          1985

                                   Finland             Exposure limit value (TWA)                  240 mg/m3          1981

                                   Germany,            Maximum work-site concentration             withdrawn          1986 (r)
                                     Federal                                                       (carcinogenicity)
                                     Republic of

                                   Netherlands         Maximum limit (TWA)                         240 mg/m3          1985 (r)

                                   Romania             Maximum permissible concentration (TWA)     100 mg/m3          1985 (r)
                                                       Ceiling value                               200 mg/m3          1985 (r)

                                   Sweden              Threshold limit value (TWA)                  12 mg/m3          1985

                                   Sweden              Short-term exposure limit                    25 mg/m3          1985
                                                       (15-min TWA)

                                   United Kingdom      Threshold limit value (TWA)                  50 mg/m3b         1985 (r)
                                                       Short-term exposure limit                   240 mg/m3b         1985 (r)
                                                       (10-min TWA)

                                   USA (OSHA)          Permissible exposure limit                  240 mg/m3          1974

                                   USA (AUEIH)         Threshold limit value (TWA)                  50 mg/m3          1976

                                   USSR                Ceiling value                                 1 mg/m3          1977


    Medium      Specification      Country/            Exposure limit descriptiona                 Value            Effective
                                   organization                                                                       Date

    AIR         Ambient            USSR                Maximum allowable concentration             0.08 mg/m3         1984
                                                       (once per day)

    WATER       Surface            USSR                Maximum allowable concentration             0.01 mg/litre      1983

                Fishing            USSR                Maximum allowable concentration             0.005 mg/litre     1982 (r)

    FOOD        Specified          USA                 Residue tolerance                           300-700 mg/kg      1985 (r)


    a TWA = time-weighted average over one working day (usually 8 h)
    b Intended change.

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    WHO (1985)  EHC No. 56: Propylene Oxide. Geneva, World Health

    See Also:
       Toxicological Abbreviations
       Propylene oxide (EHC 56, 1985)
       Propylene oxide (ICSC)
       PROPYLENE OXIDE (JECFA Evaluation)
       Propylene Oxide (IARC Summary & Evaluation, Volume 60, 1994)