Health and Safety Guide No. 6






    This is a companion volume to Environmental Health Criteria 32:
    Methylene Chloride

    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

    ISBN 92 4 154332 9
    ISSN 0259-7268

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    (c) World Health Organization 1987

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    proprietary products are distinguished by initial capital letters.






         1.1. Identity
         1.2. Physical and chemical properties
         1.3. Composition
         1.4. Uses

         2.1. Exposure to methylene chloride
         2.2. Uptake, metabolism and excretion
         2.3. Effects on animals
         2.4. Effects on human beings


         4.1. Main hazards for man, prevention and protection,
               first aid
         4.2. Advice to physicians
         4.3. Health surveillance advice
         4.4. Explosion and fire hazards
               4.4.1. Explosion hazards
               4.4.2. Fire hazards
               4.4.3. Prevention
               4.4.4. Extinguishing agents
         4.5. Storage
         4.6. Transport
         4.7. Spillage and disposal
               4.7.1. Spillage
               4.7.2. Disposal (based on the IRPTC waste disposal



         7.1. Exposure limit values
         7.2. Specific restrictions
         7.3. Labelling, packaging, and transport
         7.4. Other measures



    The International Programme on Chemical Safety is responsible for the
    publication of a series of Environmental Health Criteria documents,
    each of which assesses the existing information on the relationship
    between exposure to a specific chemical, mixture of chemicals, or
    combination of chemicals and physical and biological agents, and man's
    health and the integrity of the environment. The documents provide
    guidelines for setting exposure limits consistent with the protection
    of human health and the environment.

    To facilitate the application of these guidelines in national chemical
    safety programmes, "Health and Safety Guides" are being prepared,
    highlighting the information contained in the documents for those who
    need to know the health and environmental issues involved, but not the
    scientific details. The Guides include advice on preventive and
    protective measures and emergency action.

    Review and revision of the information in this Health and Safety Guide
    will take place in due course, and the eventual aim is to use
    standardized terminology. We should be grateful if you would help by
    telling us of any difficulties encountered in using the information in
    this guide.

    Comments please, addressed to:

    The Manager
    International Programme on Chemical Safety
    Division of Environmental Health
    World Health Organization
    1211 Geneva 27


    All people in the work-place environment should be given the relevant
    written information in this book, supplemented by a clear, personal
    explanation to ensure that they are fully aware of the dangers and the
    current courses of protective and emergency action.

    The International Chemical Safety Card should be displayed as directed
    and its contents clearly explained to all working personnel.

    Medical staff should be fully conversant with the medical information
    to ensure they can act rapidly and efficiently in an emergency.

    Posters should be used to give impact to basic safety measures.

    Further copies of the Health and Safety Guide and, for those requiring
    more detailed scientific information, the relevant Environmental
    Health Criteria publication, are available to order.



    1.1  Identity

    Molecular formula:             CH2C12

    Chemical structure:                 H
                                   Cl - C - Cl

    Common trade names:            Aerothene MM; Freon 30; Narkotil;
                                   Solaesthin; Solmethine

    Common synonyms:               DCM; dichloromethane; methane
                                   dichloride; methylene bichloride;
                                   methylene dichloride; methylenum

    CAS registry number:           75-09-2

     Conversion factor

    1 mg/m3 = 0.288 ppm
    1 ppm methylene chloride = 3.47 mg/m3 at 25C and 101.3 kPa
    (760 mm Hg).

    1.2  Physical and Chemical Properties

    Some physical and chemical properties of methylene chloride are given
    in the Sample International Chemical Safety Card.

    1.3  Composition

    Technical products contain 0.0001-1% of stabilizers. Paint-stripping
    formulations usually contain about 80% by weight of methylene
    chloride, often in combination with methanol.

    1.4  Uses

    Methylene chloride is widely used as a solvent and paint remover. It
    is also used as a blowing agent for polyurethane, as a propellant in
    aerosols such as insecticides, hair sprays, shampoos, and paints, as a
    component in fire-extinguishing products, as an insecticidal fumigant
    for grains, and as a coolant or refrigerant.


    2.1  Exposure to Methylene Chloride

    The main route of human exposure is through inhalation. High
    concentrations of methylene chloride have been measured indoors in the
    industrial environment and when using methylene chloride as a paint

    The general population is exposed to much lower levels in the ambient
    air and in drinking-water and food. It is estimated that about 80% of
    the world production of methylene chloride is released into the
    atmosphere, but degradation of the compound by sunlight takes place at
    a rate that makes accumulation in the atmosphere unlikely. The initial
    degradation products are phosgene and carbon monoxide, which are
    transformed into carbon dioxide and hydrochloric acid. When methylene
    chloride is present in surface water, most of it will evaporate. The
    compound is readily biodegradable, when oxygen is present, and
    bioaccumulation seems unlikely. The behaviour of the compound in the
    soil has yet to be determined.

    2.2  Uptake, Metabolism, and Excretion

    Absorption of liquid methylene chloride via the skin is slow.
    Methylene chloride is rapidly absorbed via the gastrointestinal tract
    and crosses the placenta and blood-brain barrier.

    At exposure levels normally encountered, most of the methylene
    chloride taken up is degraded to carbon monoxide, and probably carbon
    dioxide. It is also exhaled unchanged. At higher exposure levels, not
    all the methylene chloride taken up can be degraded, and some may be
    stored in adipose tissue.

    2.3  Effects on Animals

    Single oral doses of methylene chloride at 3000 mg/kg body weight and
    vapour concentrations of 52000 mg/m3 for 6 h have been shown to be
    lethal for 50% of exposed rats in a population (LD50, LC50,
    respectively). Thus, according to the scale of Hodge & Sterner,
    methylene chloride is "slightly toxic" for rats after oral exposure
    and "practically non-toxic" after inhalation exposure.

    Methylene chloride has been shown to cross the placental barrier and
    to accumulate in fetal tissue and breast milk. In one study, designed
    to assess teratogenic potential, rats and mice were exposed by
    inhalation to 4340 mg methylene chloride/m3 during days 6-15 of
    gestation. There was an increased incidence of extra sternebrae in the
    offspring of mice and an increased incidence of dilated renal pelvis
    in rat offspring.

    In the only reproduction study available for review, no reproductive
    impairment was found when rats were allowed to mate after receiving
    125 mg methylene chloride/litre drinking-water for 13 weeks.

    Methylene chloride is mutagenic in bacteria, fungi, and in the fruit
    fly. However, the results of most tests on mammalian somatic cells,
    including human cells, have been negative.

    Data available to the Task Group were inadequate for assessing whether
    methylene chloride should be considered carcinogenic for animals and
    man. However, the Task Group made this evaluation in September, 1983.
    More recently, results have become available from US NTP inhalation
    studies on rats and mice. Under the conditions of these studies, there
    was some evidence that methylene chloride was carcinogenic for male
    rats, and there was clear evidence that it was carcinogenic for female
    rats, and male and female mice.

    Methylene chloride is only slightly toxic for aquatic organisms,
    concentrations of between 190 and 330 mg/litre being lethal for half
    the number of organisms (LC50) exposed for 4 days.

    2.4  Effects on Human Beings

    Exposure to methylene chloride can be estimated roughly by the
    determination of levels in blood or expired air. Exposure may result
    in elevated carboxyhaemoglobin levels in the blood. However, it should
    be kept in mind that blood-carboxyhaemoglobin levels can also be
    affected by exercise or smoking.

    As the metabolism of methylene chloride is a saturable process,
    carboxyhaemoglobin levels in blood do not increase linearly with
    exposure. The normal levels of blood-carboxyhaemoglobin in man are
    exceeded in non-smoking, resting individuals after inhalation exposure
    to a methylene chloride concentration of 400 mg/m3 for 7.5 h. The
    odour recognition threshold for methylene chloride is above
    concentrations that have resulted in adverse effects and should not be
    used as a warning signal.

    Initial, mild adverse effects on behaviour are observed in
    non-smoking, healthy persons after inhalation of methylene chloride
    vapour at a concentration of 690 mg/m3 for 1.5-3 h.

    Impairment of psychomotor performance occurs after a 4-h exposure to
    2610 mg/m3. Narcosis occurred following exposure to 69000 mg/m3 for
    30 min.

    Individuals with heart disease may be especially at risk when exposed
    to methylene chloride, because of the deficiency of oxygen induced by
    carbon monoxide, bound to haemoglobin.

    The vapour of methylene chloride is moderately irritating for the eyes
    and respiratory tract. The liquid may cause severe irritation of skin
    and eyes.

    The main chronic effects in human beings are nervous system depression
    and an elevated carboxyhaemoglobin concentration in the blood.
    However, no exposure-related increases in subjective symptoms,
    neurobehavioural effects, motor nerve conduction velocity changes,
    electrocardiogram changes, or clinical effects were noted in workers
    exposed for several years to methylene chloride levels of between
    260-347 mg/m3, compared with controls.

    In 2 human epidemiological mortality studies, there was no excess
    mortality due to cancer compared with control populations. According
    to a previous evaluation of all available published epidemiological,
    experimental, and short-term test data, an IARC Working Group
    concluded that methylene chloride could not be classified with regard
    to its carcinogenicity for human beings.


    Animal experimental data and human epidemiological data are inadequate
    for assessing whether or not methylene chloride should be considered
    carcinogenic for animals and man.

    From: Environmental Health Criteria 32: Methylene Chloride

    However, in view of recent findings in inhalation studies on rats and
    mice, which became available after the Task Group meeting, methylene
    chloride should be regarded as a potential human carcinogen.


    4.1  Main Hazards for Man, Prevention and Protection, First Aid

    Methylene chloride vapour irritates the eyes and respiratory tract. At
    high levels of exposure, it may produce pulmonary oedema. The
    compound, which is metabolized to carbon monoxide, affects the central
    nervous system and induces an increase in the blood-carboxyhaemoglobin
    content. The liquid is severely irritating to the skin and eyes and
    can cause corneal damage. It is a potential human carcinogen.

    The human health hazards associated with certain types of exposure to
    methylene chloride, together with preventive and protective measures
    and first aid recommendations are listed in the following table.
    Patients with ischaemic heart disease are especially at risk.


     1. Do not smoke, drink, or eat in the work-place.

     2. In case of overexposure, the victim should leave, or be removed
     from, the contaminated area to fresh air as rapidly as possible.

     3. Remove contaminated clothing and shoes and wash with plenty of
     water and soap.

     4. Flush affected eye(s) with water for at least 15 minutes.

    4.2  Advice to Physicians

    No specific antidote is known. Treat symptomatically. Administer
    oxygen if needed.

    Do not administer fats, oils, alcohol, epinephrine, or ephedrine. Pay
    attention to signs of anoxaemia, impending pulmonary oedema, and
    ischaemia of the heart. Monitor ECG. Treat skin as for a thermal burn.

    4.3  Health Surveillance Advice

    Persons handling methylene chloride should frequently undergo periodic
    medical examination with emphasis on the functioning of the central
    nervous system and irritation of the skin and eyes. Monitoring of
    blood-carboxyhaemoglobin concentrations can give an indication of the
    extent of exposure.

        ROUTE                HEALTH HAZARDS                            PREVENTION AND PROTECTION              FIRST AID


    SKIN                 Irritation by liquid                      Avoid exposure; wear                   Remove contaminated clothing
                                                                   protective clothing and gloves         and shoes; wash with plenty of
                                                                                                          water and soap

    EYES                 Irritation by both liquid and             Wear safety goggles if there is        Flush with plenty of water for
                         vapour                                    a possibility of eye contact           at least 15 minutes

    INHALATION           Headache; nausea; dullness;               Avoid exposure; apply                  Victim should be removed to
                         dizziness; irritation of respiratory      ventilation, local exhaust, or         fresh air and kept quiet;
                         tract with severe overexposure;           breathing protection by a              administer oxygen, if needed; if
                         effects on the central nervous            suitable respirator                    breathing has stopped, apply
                         system, such as behavioural                                                      artificial respiration
                         disturbances, fatigue, weakness,          Do not depend on odour to
                         headache, pulmonary oedema,               warn of overexposure
                         unconsciousness, death; hypoxia
                         induced by elevated
                         blood-carboxyhaemoglobin content
                         may be hazardous for persons with
                         heart disease or anaemia

    INGESTION            See inhalation                            Do not eat, drink, or smoke            Rinse mouth; give plenty of
                                                                   when handling methylene                water to drink (no fats, oils,
                                                                   chloride                               milk); induce vomiting in
                                                                                                          conscious patients

    ROUTE                HEALTH HAZARDS                            PREVENTION AND PROTECTION              FIRST AID

    GENERAL              Potential human carcinogen


    INHALATION           Irritation of eyes and respiratory        Avoid exposure; apply
                         tract; effects on central nervous         ventilation or local exhaust;
                         system, which may be permanent;           good public health policy
                         elevated blood-carboxyhaemoglobin         would suggest that particular
                         content                                   attention should be paid to
                                                                   pregnant or nursing women

    4.4  Explosion and Fire Hazards

    4.4.1  Explosion hazards

    Methylene chloride may react explosively with light metals (lithium,
    sodium, potassium, aluminium, magnesium) as well as with alloys of
    sodium. Explosive mixtures are formed with dinitrogen tetroxide
    (N2O4), dinitrogen pentoxide (N2O5), nitric acid, and compressed

    4.4.2  Fire hazards

    Methylene chloride is flammable in an atmosphere with an increased
    oxygen content. In pure oxygen, the flammable limits (explosive
    limits) are 15.5 and 66.4%. Methylene chloride is also flammable if
    small amounts of combustible material are added. The compound
    decomposes in contact with open flames and glowing surfaces with the
    formation of harmful gases, such as hydrogen chloride, which forms
    mists of hydrochloric acid with moisture, and phosgene.

    4.4.3  Prevention

    Do not use methylene chloride in the vicinity of a fire, a hot surface
    (e.g., a portable heating unit), or during welding. Do not smoke. Do
    not add any combustible material to methylene chloride. Avoid using
    compressed oxygen when handling methylene chloride. Avoid contact
    between the compound and light metals, alloys of light metals,
    dinitrogen tetroxide, dinitrogen pentoxide, nitric acid, or liquid
    oxygen. In case of fire, keep drums cool by spraying with water.

    4.4.4  Extinguishing agents

    Carbon dioxide, powder, foam.

    4.5 Storage

    Methylene chloride can react with iron, some stainless steels, copper,
    nickel, aluminium, and other metals. Rubber and polyvinyl chloride are
    not resistant to the compound. Methylene chloride can be stored in
    air-tight containers made of plain, galvanized, or lead-lined, mild
    steel, or glass. Store in well-labelled containers away from metals
    and foodstuffs, in cool, dry areas with ventilation across the floor,
    under shaded conditions away from radiant heat.

    4.6  Transport

    Methylene chloride can be transported in plain, galvanized, or
    lead-lined, mild steel air-tight containers.

    4.7  Spillage and Disposal

    4.7.1  Spillage

    Areas with spills should be evacuated and well ventilated. Collect
    leaking liquid in a sealable container. Absorb spilled liquid in sand
    or other inert absorbent and remove to a safe place. Neutralize the
    remainder with chlorine bleaching liquor. Ensure personal protection
    by wearing self-contained breathing apparatus.

    4.7.2  Disposal (based on the IRPTC waste disposal file)

    Incineration, preferably after mixing with a combustible fuel. Assure
    complete combustion to prevent formation of phosgene. An acid scrubber
    is necessary to remove haloacids produced. The haloacids can be
    recovered from waste gases and reused.


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


    (DCM, dichloromethane, methylene dichloride) (CH2Cl2)

    PHYSICAL PROPERTIES                                                                  OTHER CHARACTERISTICS

    Relative molecular mass                         84.93                                Colourless liquid with a chloroform-like
    Appearance                                      colourless liquid                    odour; the compound decomposes in contact
    Odour                                           chloroform-like                      with open flames and glowing surfaces
    Odour perception threshold                      743 mg/m3                            with formation of harmful gases; explosive
    Melting point (C)                              -95                                  mixtures may be formed with light metals,
    Boiling point (C)                              40                                   nitric acid, compressed oxygen, N2O4, and
    Solubility in water (20C)                      20 g/litre                           N2O5; methylene chloride is flammable only
    Density (20C)                                  1.33 g/ml                            if the oxygen content of the atmosphere is
    Relative vapour density                         2.93                                 increased or if small amounts of
    Vapour pressure (20C)                          46.52 kPa (349 mm Hg)                combustible material are added
    Flammable limits in pure oxygen (%)             15.5-66.4
    Octanol/water partition coefficient             1.25
    Surface tension                                 28.12 dyne/cm (20C)

    HAZARDS/SYMPTOMS                           PREVENTION AND PROTECTION                 FIRST AID

    SKIN: Irritation; redness                  Avoid exposure; wear                      Remove contaminated clothing; wash skin with
                                               protective clothing and gloves            plenty of water

    EYES: Irritation; redness                  Wear safety goggles if there              Flush eyes with plenty of water for at
                                               is a possibility of eye contact           least 15 min.


    PHYSICAL PROPERTIES                                                                  OTHER CHARACTERISTICS

    INHALATION: Headache, nausea,              Avoid exposure by use of                  Fresh air, rest; if breathing has stopped,
    dullness, dizziness, pulmonary             ventilation, local exhaust, or            apply artificial respiration; administer
    irritation; with severe overexposure,      breathing protection                      oxygen, if required; in serious cases, seek
    effects on the central nervous system,                                               medical attention immediately
    and pulmonary oedema

    INGESTION: An unlikely                     Do not eat, drink, or smoke               Rinse mouth; give plenty of water to
    occupational hazard; abdominal pain;       when handling the                         drink (no fats, oils, milk); do not induce
    effects on the central nervous system      compound                                  vomiting in conscious patients

    GENERAL: The use of alcoholic
    beverages enhances toxic effects;
    potential human carcinogen

    SPILLAGE                                   STORAGE                                   FIRE AND EXPLOSION

    Collect leaking liquid in sealable         Store in shaded conditions,               Not flammable under ordinary conditions;
    containers; absorb spills in sand or       away from radiant heat, in                avoid using compressed oxygen; keep away
    other inert absorbent and remove           labelled air-tight containers,            from combustible materials; in case of fire,
    to a safe place; neutralize the            made of plain, galvanized or              keep drums cool by spraying with water;
    remainder with chlorine bleaching          lead-lined; mild steel or                 toxic decomposition products may be
    liquor; take care of personal              glass; store separate from                generated
    protection (use of self-contained          metals and foodstuffs;
    breathing apparatus)                       ventilation across the floor


    PHYSICAL PROPERTIES                                                                  OTHER CHARACTERISTICS


    Waste should be incinerated,               National Occupational                     UN: 1593
    preferably after mixing with a             Exposure Limit:
    combustible fuel; assure complete          National Poison Control
    combustion; apply acid scrubbing           Centre:

    FIGURE 1

    Note: In cases with adverse health effects, always call a doctor or transport to hospital. Methylene chloride may elevate the
    blood-carboxyhaemoglobin content and may therefore be extra hazardous for persons with heart disease and anaemia. Pregnant and
    nursing women should be particularly careful. Do not use the compound in the vicinity of a fire, a hot surface, or during welding.
    Do not smoke. Do not depend on odour as a warning of overexposure.

    Methylene chloride has a low toxicity for aquatic organisms. Avoid
    contamination of soil, water, and the atmosphere by using proper
    methods of storage, transport, handling, and waste disposal. In case
    of spillage, use the methods advised in section 4.7.

    Losses to the atmosphere can be minimized by the use of adsorption
    techniques using activated carbon.


    The information given in this paragraph has been extracted from the
    International Register of Potentially Toxic Chemicals (IRPTC) legal

    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 full reference to the
    original national document from which the information was extracted
    can be obtained from the IRPTC.a

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

    7.1  Exposure Limit Values

    See following table.

    7.2  Specific Restrictions

    In Kenya, methylene chloride is a permitted food additive as a
    solvent. Food products in or on which it is permitted and maximum
    levels of use are listed (1978 (r)).

    The European Community legislation allows the presence of methylene
    chloride, in cosmetic products for marketing, only at concentrations
    below 35% in the final product. In the case of aerosol preparations,
    the mandatory label must state "Aerosol: No spraying on naked flame or
    incandescent material".

    7.3  Labelling, Packaging, and Transport

    The European Community legislation requires labelling as a dangerous
    substance using the symbol:

    FIGURE 2


    a  International Register of Potentionally Toxic Chemicals, Palais des
       Nations, 1211 Geneva 10, Switzerland (Telephone No. 988400-985850).

    The label must read: harmful by inhalation - avoid contact with skin.

    The European Community legislation on labelling solvent preparations
    classifies methylene chloride in Class  II d for the purpose of
    determining the label on solvent preparations containing this

    The United Nations Committee of Experts on the Transport of Dangerous
    Goods classifies methylene chloride as a poisonous substance (Class
    6.1) with minor danger for packaging purpose (Packing Group III).
    Packaging methods and label are recommended (1982 (r)).

    The International Maritime Organization also classifies methylene
    chloride as a poisonous substance (Class 6.1) and recommends package,
    storage, and labelling methods for maritime transport in glass
    bottles, cans, and drums. It is stressed that phosgene fumes are
    formed when methylene chloride is involved in a fire and that storage
    should be under shaded conditions, away from radiant heat (1977 (r)).

    The label recommended by both organizations is:

    FIGURE 3

    7.4  Other Measures

    The European Community legislation on the discharge of dangerous
    substances into the aquatic environment prohibits the discharge of
    methylene chloride into groundwater. For other waters, it requires
    that national authorities give specific discharge authorizations with
    discharge conditions (total quantity and concentrations).


    Medium     Specification    Country/               Exposure limit description                            Value               Effective
                                organization                                                                                     date

    AIR        Occupational     Australia              Threshold limit value (TLV)                                               1983 (r)
                                                       -- Time-weighted average                              720 mg/m3

                                Belgium                Threshold limit value (TLV)                           720 mg/m3

                                Czechoslovakia         Maximum allowable concentration (MAC)                                     1985
                                                       -- Time-weighted average                              500 mg/m3
                                                       -- Ceiling value                                      2500 mg/m3

                                Finland                Maximum permissible concentration (MPC)                                   1982 (r)
                                                       -- Time-weighted average                              1740 mg/m3

                                German Democratic      Maximum allowable concentration MAC                                       1983 (r)
                                Republic               -- Time-weighted average                              500 mg/m3
                                                       -- Short-term exposure limit (STEL)                   1500 mg/m3

                                Germany, Federal       Biological tolerable value (BAT)                                          1985 (r)
                                Republic of            -- Blood-carboxyhaemoglobin at end of shift           5% CO-Hb

                                Germany, Federal       Maximum work-site concentration (MAK)                                     1985 (r)
                                Republic of            -- 8-h time-weighted average                          360 mg/m3
                                                       -- 30-min short-term exposure limit (STEL),           1800 mg/m3
                                                       2  per shift (average value)

                                Hungary                Maximum allowable concentration (MAC)                                     1978 (r)
                                                       -- Time-weighted average                              50 mg/m3
                                                       -- Short-term exposure limit (STEL) (30 min)          250 mg/m3


    Medium     Specification    Country/               Exposure limit description                            Value               Effective
                                organization                                                                                     date

                                Italy                  Threshold limit value (TLV)                           360 mg/m3

                                Japan                  Maximum allowable concentration (MAC)                                     1984
                                                       -- Time-weighted average                              360 mg/m3

                                Netherlands            Maximum limit                                                             1985 (r)
                                                       -- Time-weighted average                              700 mg/m3
                                                       -- Intended time-weighted average                     350 mg/m3
                                                       -- Short-term exposure limit (STEL)                   1765 mg/m3

                                Poland                 Maximum Permissible Limit (MPC)                                           1982 (r)
                                                       -- Ceiling value                                      50 mg/m3

                                Romania                Maximum Permissible Limit (MPC)                                           1975 (r)
                                                       -- Time-weighted average                              500 mg/m3
                                                       -- Ceiling value                                      700 mg/m3

                                Switzerland            Maximum work-site concentration (MAK)                                     1984 (r)
                                                       -- Time-weighted average                              360 mg/m3

    AIR        Occupational     Sweden                 Hygienic limit value (HLV)                                                1985
                                                       -- One day time-weighted average                      250 mg/m3
                                                       -- Short-term exposure limit (STEL) (15 min)          500 mg/m3

                                United                 Recommended limits                                                        1985 (r)
                                Kingdom                -- Time-weighted average                              700 mg/m3
                                                       -- Short-term exposure limit (STEL) (10 min)          870 mg/m3


    Medium     Specification    Country/               Exposure limit description                            Value               Effective
                                organization                                                                                     date

                                USA (ACGIH)            Threshold limit value (TLV)                                               1984 (r)
                                                       -- Time weighted average                              360 mg/m3
                                                       Short-term exposure limit (STEL)                      1700 mg/m3
                                                       (intended to be deleted)

                                USA (OSHA)             Permissible exposure limit (PEL)                                          1981 (r)
                                                       -- Time-weighted average                              1736 mg/m3
                                                       -- Ceiling value                                      3472 mg/m3
                                                       -- Peak concentration (5 min in any 2-h period)       6945 mg/m3

                                USSR                   Maximum allowable concentration (MAC)                                     1977
                                                       -- Ceiling value of vapour                            50 mg/m3

                                Yugoslavia             Maximum allowable concentration (MAC)                                     1971 (r)
                                                       -- Time-weighted average                              500 mg/m3

    AIR        Ambient          Czechoslovakia         Maximum allowable concentration (MAC)                                     1975 (r)
                                (Immission             -- Average per day                                    1.0 mg/m3
                                standard)              -- Average per 0.5 h                                  3.0 mg/m3

                                USSR                   Maximum allowable concentration (MAC)                                     1984
                                                       -- One time per day                                   8.8 mg/m3

    WATER      Surface          USSR                   Maximum allowable concentration (MAC)                 7.5 mg/litre        1983


    Medium     Specification    Country/               Exposure limit description                            Value               Effective
                                organization                                                                                     date

    FOOD                        FAO/WHO                Acceptable daily intake (ADI)                         none allocated      1971

                                USA                    Maximum permissible concentration (MPC)                                   1981
                                                       -- In spice oleoresins                                30 mg/kg
                                                       -- In hops extract                                    2.2% (wt/wt)
                                                       -- In decaffeinated coffee                            10 mg/kg
                                                       -- In food additive modified hop extract              5-150 mg/kg
                                                       -- In specified food colour additives                 30 mg/kg

    FOOD       Plant            USA                    Exempted from tolerance requirements when used                            1981
               Animal                                  as a fumigant after harvest for certain
                                                       specified plant products, when used according
                                                       to good agricultural practice as inert ingredient
                                                       of pesticides for some specified purposes

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

    See Also:
       Toxicological Abbreviations
       Methylene chloride (EHC 164, 1996, 2nd edition)
       Methylene chloride (EHC 32, 1984, 1st edition)
       Methylene chloride (PIM 343)