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    IPCS INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY
    Health and Safety Guide No. 90




    ACETALDEHYDE
    HEALTH AND SAFETY GUIDE





    UNITED NATIONS ENVIRONMENT PROGRAMME

    INTERNATIONAL LABOUR ORGANISATION

    WORLD HEALTH ORGANIZATION



    WORLD HEALTH ORGANIZATION, GENEVA 1994


    This is a companion volume to Environmental Health Criteria
    167: Acetaldehyde

    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

    Acetaldehyde : health and safety guide.

    (Health and safety guide ; no. 90)

    1.Acetaldehyde - adverse effects 2.Acetaldehyde - toxicity
    3.Environmental exposure  I.Series

    ISBN 92 4 151090 0          (NLM Classification: QU 99)
    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 1994

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

    The designations employed and the presentation of the material in
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    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
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    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. Composition
         1.4. Analysis
         1.5. Production and uses

    2. SUMMARY
         2.1. Identity, physical and chemical properties, and
              analytical methods
         2.2. Sources of human and environmental exposure
         2.3. Environmental transport, distribution, and
              transformation
         2.4. Environmental levels and human exposure
         2.5. Kinetics and metabolism
              2.5.1. Absorption, distribution, and elimination
              2.5.2. Metabolism
              2.5.3. Reaction with other components
         2.6. Effects on organisms in the environment
              2.6.1. Aquatic organisms
              2.6.2. Terrestrial organisms
         2.7. Effects on experimental animals and  in vitro
              test systems
              2.7.1. Single exposure
              2.7.2. Short- and long-term exposures
              2.7.3. Reproduction, embryotoxocity, and
                        teratogenicity
              2.7.4. Mutagenicity and related end-points
              2.7.5. Carcinogenicity
              2.7.6. Special studies
         2.8. Effects on humans

    3. EVALUATION AND CONCLUSIONS

    4. HUMAN HEALTH HAZARDS, PREVENTION AND PROTECTION, EMERGENCY
         ACTION
         4.1. Human health hazards, prevention and
              protection, first aid
         4.2. Advice to physicians
         4.3. Health surveillance advice
         4.4. Explosion and fire hazards, prevention
              4.4.1. Explosion and fire hazards
              4.4.2. Prevention
              4.4.3. Fire extinguishing agents
         4.5. Storage
         4.6. Transport
         4.7. Spillage

    5. HAZARDS FOR THE ENVIRONMENT AND THEIR PREVENTION

    6. SUMMARY OF CHEMICAL SAFETY INFORMATION

    7. CURRENT REGULATIONS, GUIDELINES, AND
         STANDARDS
         7.1. Exposure limits
         7.2. Specific restrictions
         7.3. Labelling, packaging, and transport
         7.4. Discharges, waste disposal

    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

    1. PRODUCT IDENTITY AND USES

    1.1  Identity

    Chemical formula:        C2H4O

    Chemical structure:

                                 H
                                 '
                             H - C - C = O
                                 '   '
                                 H   H

    Common name:             acetaldehyde

    Common synomyms:         acetic aldehyde, acetylaldehyde, ethanal,
                             ethylaldehyde, diethyl acetal, 1,1-diethoxy
                             ethane

    CAS registry number:     75-07-0

    RTECS registry number:   AB 1925000

    Conversion factors:      1 ppm acetaldehyde =
                                 1.8 mg acetaldehyde/m3 air

                             1 mg acetaldehyde/m3 air =
                                 0.56 ppm acetaldehyde

                             at 25 C and 101.3 kPa (760 mmHg).

    1.2  Physical and Chemical Properties

    Acetaldehyde is a mobile liquid with a pungent suffocating odour
    that is somewhat fruity and pleasant in dilute concentrations. The
    odour threshold for acetaldehyde in air is reported to be 0.09
    mg/m3 (0.05 ppm).

    The compound is miscible in all proportions with water and most
    common organic solvents.

    The most important physical and chemical properties of acetaldehyde
    are presented in the Summary of Chemical Safety Information (page
    21).

    1.3  Composition

    Commercial acetaldehyde should contain at least 99% of the compound
    and the acidity (as acetic acid) should be maximal 0.1%.

    1.4  Analysis

    The most specific and sensitive method, widely used, is based on the
    derivatization of acetaldehyde (in most cases by
    2,4-dinitro-phenylhydrazine) and subsequent analysis of the
    hydrazone derivatives by high pressure liquid chromatography (HPLC)
    or gas chromatography (GC). Analytical methods are available for the
    detection of acetaldehyde in air, water, beverages, and blood.

    1.5  Production and Uses

    In Japan, production was estimated to be 328 000 tonnes in 1981.  In
    1982, the total acetaldehyde production in the USA amounted to 281
    000 tonnes while in Western Europe, production was 706 000 tonnes in
    1983.

    Around 80% of the total production of acetaldehyde is made by
    liquid-phase oxidation of ethylene using a catalytic solution of
    palladium and copper chlorides. The remainder is produced by the
    oxidation of ethanol and the hydration of acetylene.

    The greater part of the acetaldehyde produced is used in the
    production of acetic acid. It is also used in flavourings, foods,
    beverages, perfumes, plastics, aniline dyes, synthetic rubber
    manufacturing, the silvering of mirrors, gelatin fibre hardening,
    and in the laboratory.

    2.  SUMMARY

    2.1  Identity, Physical and Chemical Properties, and Analytical
         Methods

    Acetaldehyde is a colourless volatile liquid with a pungent
    suffocating odour. The reported odour threshold is 0.09 mg/m3.
    Acetaldehyde is a highly flammable and reactive compound that is
    miscible in water and most common solvents.

    Analytical methods are available for the detection of acetaldehyde
    in air (including breath) and water. The principal method is based
    on the reaction of acetaldehyde with 2,4-dinitrophenylhydrazine and
    the subsequent analysis of the hydrazone derivatives using
    high-pressure liquid chromatography or gas chromatography.

    2.2  Sources of Human and Environmental Exposure

    Acetaldehyde is a metabolic intermediate in humans and higher plants
    and a product of alcohol fermentation. It has been identified in
    food, beverages, and cigarette smoke. It is also present in vehicle
    exhaust and in wastes from various industries. Degradation of
    hydrocarbons, sewage, and solid biological wastes produces
    acetaldehyde, as well as open burning and incineration of gas, fuel
    oil, and coal.

    More than 80% of acetaldehyde used commercially is produced by the
    liquid-phase oxidation of ethylene with a catalytic solution of
    palladium and copper chlorides.

    The annual emission of acetaldehyde from all sources in the USA is
    estimated to be 12.2 million kg.

    2.3  Environmental Transport, Distribution, and Transformation

    Intercompartmental transport of acetaldehyde is expected to be
    limited because of its high reactivity. However, some transfer of
    acetaldehyde to air from water and soil is expected, because of its
    high vapour pressure and low sorption coefficient.

    It is suggested that the photo-induced atmospheric removal of
    acetaldehyde occurs predominantly via radical formation. Photolysis
    is expected to contribute another substantial fraction to the
    removal process. Both processes cause a reported daily loss of about
    80% of atmospheric acetaldehyde emissions. Reported half-lives of
    acetaldehyde in water and air are 1.9 h and 10-60 h, respectively.

    Acetaldehyde is readily biodegradable.

    2.4  Environmental Levels and Human Exposure

    Levels of acetaldehyde in ambient air generally average 5 g/m3.
    Concentrations in water are generally less than 0.1 g/litre.
    Analysis of a wide range of foodstuffs in the Netherlands showed
    that concentrations were generally less than 1 mg/kg (1 ppm), but,
    occasionally, they ranged up to several 100 mg/kg, particularly in
    some fruit juices and vinegar.

    The principal source of exposure to acetaldehyde for the majority of
    the general population is through the metabolism of alcohol.
    Cigarette smoke is also a significant source of exposure. With
    respect to other media, the general population is exposed to
    acetaldehyde mainly from food and beverages and, to a lesser extent,
    from air. The amounts contributed to total intake from
    drinking-water are negligible.

    Available data are inadequate to determine the extent of exposure to
    acetaldehyde in the workplace. Workers may be exposed in some
    manufacturing industries and in alcohol fermentation where the
    principal route of exposure is most likely inhalation and possibly,
    dermal contact.

    2.5  Kinetics and Metabolism

    2.5.1  Absorption, distribution, and elimination

    Available studies on toxicity indicate that acetaldehyde is absorbed
    through the lungs and gastrointestinal tract, but no adequate
    quantitative studies have been identified. Absorption through the
    skin is probable.

    Following inhalation by rats, acetaldehyde is distributed to the
    blood, liver, kidney, spleen, heart, and other muscles. Low levels
    were detected in embryos after maternal i.p. injection of
    acetaldehyde (mouse) and following maternal exposure to ethanol
    (mouse and rat). Potential production of acetaldehyde has also been
    observed in rat fetuses and the human placenta  in vitro.

    Distribution of acetaldehyde to brain interstitial fluid, but not to
    brain cells, has been demonstrated following intraperitoneal
    injection of ethanol. A high affinity, low-Km ALDHa may be
    important in maintaining low levels of acetaldehyde in the brain
    during the metabolism of ethanol.

    In humans and the baboon, acetaldehyde is taken up by red blood
    cells following ethanol consumption and can,  in vivo, reach
    intracellular levels that are 10 times greater than plasma levels.

    Following oral administration, virtually no unchanged acetaldehyde
    is excreted in the urine.

    2.5.2  Metabolism

    The major pathway for the metabolism of acetaldehyde is by oxidation
    to acetate under the influence of NAD-dependent ALDH.a Acetate
    enters the citric acid cycle as acetyl-CoA. There are several
    isoenzymes of ALDH with different kinetic and binding parameters
    that influence acetaldehyde oxidation rates.

    ALDH activity has been localized in the respiratory tract epithelium
    (excluding olfactory epithelium) in the rat, in the renal cortex and
    tubules in the dog, rat, guinea-pig, and baboon, and in the testes
    in the mouse.

    Acetaldehyde is metabolized by mouse and rat embryonic tissue  in
     vitro. Acetaldehyde crosses the rat placenta despite placental
    metabolism.

    Though there is some metabolism in human renal tubules, the liver is
    the most important site of metabolism of acetaldehyde.

    Several isoenzymic forms of ALDH have been identified in human liver
    and other tissues. There is polymorphism for the mitochondrial ALDH.
    Subjects who are homozygous or heterozygous for a point mutation in
    the mitochondrial ALDH corresponding gene have a low activity of
    this enzyme, metabolize acetaldehyde slowly, and are intolerant of
    ethanol.

    The metabolism of acetaldehyde can be inhibited by crotonaldehyde,
    dimethylmaleate, phorone, disulfiram, and calcium carbamide.

    2.5.3  Reaction with other components

    Acetaldehyde forms stable and unstable adducts with proteins. This
    can impair protein function as evidenced by inhibition of enzyme
    activity, impaired histone-DNA binding, and inhibition of
    polymerization of tubulin.

    Unstable adducts of acetaldehyde of undetermined significance occur
     in vitro with nucleic acids.

    Acetaldehyde can react with various macromolecules in the body,
    preferentially those containing lysine residues, which can lead to
    marked alterations in the biological function of these molecules.


              

    a NAD = nicotinamide adenine dinucleotide.
      ALDH = aldehyde dehydrogenase.

    2.6  Effects on Organisms in the Environment

    2.6.1  Aquatic organisms

    LC50s in fish ranged from 35 (guppy) to 140 mg/litre (species not
    specified). An EC5 of 82 mg/litre and an EC50 of 42 mg/litre
    were reported for an alga and  Daphnia magna, respectively.

    2.6.2  Terrestrial organisms

    Relatively low concentrations of acetaldehyde in air appear to be
    toxic for some microoganisms.

    Aphids were killed when exposed to acetaldehyde at a concentration
    of 0.36 g/m3 for 3 or 4 h.

    Median lethal values were 8.91 mg/litre per h and 7.69 mg/litre per
    h for the slug species,  Arion hortensis and  Agriolimax
     reticulatus, respectively.

    Inhibition of the seed germination of onion, carrot, and tomato by
    acetaldehyde (up to 1.52 mg/litre) was reversible, whereas
    inhibition of seed germination in  Palmer amaranth, similarly
    exposed, was irreversible; acetaldehyde at 0.54 g/m3 damaged
    lettuce.

    2.7  Effects on Experimental Animals and  in vitro Test Systems

    2.7.1  Single exposure

    On the basis of the LD50s in rats and mice and the LC50s in rats
    and Syrian hamsters, the acute toxicity of acetaldehyde is low.
    Acute dermal studies were not available.

    2.7.2  Short- and long-term exposures

    In repeated dose studies by both the oral and inhalation routes,
    toxic effects at relatively low concentrations were limited
    principally to the sites of initial contact. In a 28-day study in
    which acetaldehyde was administered in the drinking-water to rats,
    effects were limited to slight focal hyperkeratosis of the
    forestomach at 675 mg/kg body weight (no-observed-effect level
    (NOEL): 125 mg/kg body weight). Following administration of a single
    dose level of 0.05% in the drinking-water for 6 months (estimated by
    the Task Group to be approximately 40 mg/kg body weight),
    acetaldehyde induced synthesis of rat liver collagen, an observation
    that was supported by  in vitro data.

    Following inhalation, NOELs for respiratory effects were 275
    mg/m3 in rats exposed for 4 weeks and 700 mg/m3 in hamsters
    exposed for 13 weeks. At lowest-observed-effect levels, degenerative
    changes of the olfactory epithelium in rats (437 mg/m3) and
    trachea in hamsters (2400 mg/m3) were observed. Degenerative
    changes of the respiratory epithelium and larynx were observed at
    higher concentrations. No repeated dose dermal studies were
    available.

    2.7.3  Reproduction, embryotoxicity, and teratogenicity

    In several studies, parenteral exposure of pregnant rats and mice to
    acetaldehyde induced fetal malformations. In the majority of these
    studies, maternal toxicity was not evaluated. No data on
    reproductive toxicity were identified.

    2.7.4  Mutagenicity and related end-points

    Acetaldehyde is genotoxic  in vitro, inducing gene mutations,
    clastogenic effects, and SCEs in mammalian cells in the absence of
    exogenous metabolic activation, though negative results were
    reported in adequate tests on  Salmonella. Following
    intraperitoneal injection, acetaldehyde induced SCEs in the bone
    marrow of Chinese hamsters and mice. However, acetaldehyde
    administered intraperitoneally did not increase the frequency of
    micronuclei in early mouse spermatids. There is indirect evidence
    from  in vitro and  in vivo studies to suggest that acetaldehyde
    can induce protein-DNA and DNA-DNA cross-links.

    2.7.5  Carcinogenicity

    Increased incidences of tumours have been observed in inhalation
    studies on rats and hamsters exposed to acetaldehyde. In rats, there
    were dose-related increases in nasal adenocarcinomas and squamous
    cell carcinomas (significant at all doses), and, in hamsters,
    non-significant increases in nasal and laryngeal carcinomas. All
    concentrations of acetaldehyde administered in the studies induced
    chronic tissue damage in the respiratory tract.

    2.7.6  Special studies

    Adequate studies on the potential neuro- and immunotoxicity of
    acetaldehyde were not found.

    2.8  Effects on Humans

    In limited studies on human volunteers, acetaldehyde was mildly
    irritating to the eyes and upper respiratory tract following acute
    exposure for very short periods to concentrations exceeding
    approximately 90 mg/m3 and 240 mg/m3, respectively.

    Cutaneous erythema was also observed in patch testing with
    acetaldehyde, in twelve subjects of "oriental ancestry".

    One limited investigation has been reported in which the incidence
    of cancer was examined in workers exposed to acetaldehyde and other
    compounds.

    On the basis of indirect evidence, acetaldehyde has been implicated
    as the putatively toxic metabolite in the induction of
    alcohol-associated liver damage, facial flushing, and developmental
    effects.

    3. EVALUATION AND CONCLUSIONS

    The acute toxicity in animals of acetaldehyde administered by the
    inhalation or oral route is low. Acetaldehyde is mildly irritating
    to the eyes and the upper respiratory tract in humans following
    short exposures in air to concentrations exceeding approximately 90
    mg/m3 and 240 mg/m3, respectively. Cutaneous erythema has
    been observed in patch testing of humans.

    Following oral administration of 675 mg/kg body weight per day to
    rats, a borderline increase in hyperkeratosis of the forestomach was
    observed (NOEL: 125 mg/kg body weight). In rats exposed to
    approximately 40 mg/kg body weight in the drinking-water for 6
    months, there was an increase in collagen synthesis in the liver.

    In inhalation studies, the NOELs for respiratory effects were 275
    mg/m3 in rats exposed for 4 weeks and 700 mg/m3 in hamsters
    exposed for 13 weeks.

    At concentrations that induce tissue damage in the respiratory
    tract, increased incidences of nasal adenocarcinomas and squamous
    cell carcinomas in the rat, and laryngeal and nasal carcinomas in
    the hamster have been observed. There is suggestive evidence that
    acetaldehyde causes genetic damage to somatic cells  in vivo.
    Available data are inadequate for the assessment of potential
    reproductive, developmental, neurological, or immunological effects.

    On the basis of data on irritancy in humans, a tolerable
    concentration of 2 mg/m3 has been derived. Division of an effect
    level for irritancy in the respiratory tract of rodents by an
    uncertainty factor (1000), gave a tolerable concentration of 0.3
    mg/m3. On the basis of the estimation of lifetime cancer risk
    using the method of linear extrapolation, the concentrations
    associated with a 10-5 excess lifetime risk are 11-65 g/m3.

    The limited data preclude definitive conclusions concerning the
    risks of acetaldehyde for environmental biota. However, considering
    the short half-lives of acetaldehyde in air and water and the fact
    that it is readily biodegradable, the toxicity of acetaldehyde for
    organisms in the aquatic and terrestrial environments is expected to
    be low, except, possibly, during industrial discharges and spills.

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

    4.1  Human Health Hazards, Prevention and Protection, First Aid

    The human health hazards associated with exposure to acetaldehyde,
    preventive and protective measures, and first aid measures are
    listed in the Summary of Chemical Safety Information in section 6.

    The substance can be absorbed into the body by inhalation of its
    vapour and by ingestion.

    Liquid acetaldehyde and fairly low levels of the vapour are
    irritating to the eyes, skin, and upper respiratory tract. Repeated
    exposure may result in dermatitis (rarely).

    Acute exposure to high levels of acetaldehyde vapour may result in
    pulmonary oedema, preceeded by excitement, followed by narcosis.

    Chronic effects due to acetaldehyde exposure seem unlikely, since
    inhalation of toxicologically significant levels of acetaldehyde are
    precluded by its irritant properties at fairly low levels.

    4.2  Advice to Physicians

    Inhaled steroids will help to prevent lung damage and oedema.

    In the presence of wheezy breathing, the physician may consider the
    subcutaneous application of 2-sympathomimetics, such as
    terbutaline sulfate (0.5 mg), followed, if necessary, by application
    of a suppository containing aminophylline (360 mg).

    In cases of suspected poisoning by acetaldehyde inhalation,
    attention should be paid to the lungs and upper respiratory tract
    for irritant effects.

    When a victim has breathing difficulties, 100% oxygen can be
    administered; if necessary, artificial respiration may be applied.

    4.3  Health Surveillance Advice

    Workers frequently exposed to acetaldehyde should be examined
    periodically. Consideration should be given to the skin, eyes, and
    respiratory tract.

    4.4  Explosion and Fire Hazards, Prevention

    4.4.1  Explosion and fire hazards

    Acetaldehyde is highly flammable when exposed to heat or flame
    (flashpoint, closed cup -38 C). Acetaldehyde in air can be
    explosive, explosion limits in air are 4.5-60.5 vol%. The
    autoignition temperature is 185-193 C.

    The vapour of acetaldehyde is heavier than air, and may spread along
    the ground and be ignited from a distance. Acetaldehyde can react
    violently with acid anhydrides, alcohols, ketones, phenols, NH3,
    HCN, H2S, halogens, P, isocyanates, strong alkalis, and amines.

    Reactions with cobalt chloride, mercury(II) chlorate, or mercury
    (II) perchlorate form sensitive, explosive products. Acetaldehyde
    polymerizes violently in the presence of traces of metals and acids.
    Reaction with oxygen may lead to detonation. When heated to
    decomposition, it emits acid smoke and fumes.

    4.4.2  Prevention

    Use ventilation, non-sparking tools, and closed and explosion-proof
    equipment and illumination sources. Do not smoke and do not use
    acetaldehyde near other sources of ignition. Avoid contact of
    acetaldehyde with oxidants. In case of fire, keep containers with
    acetaldehyde cool by spraying with water.

    4.4.3  Fire extinguishing agents

    Fires can be extinguished with chemical powder, alcohol-resistant
    foams, carbon dioxide, or a lot of water.

    4.5  Storage

    Acetaldehyde should be stored in the dark in tightly closed
    containers, under cool and fireproof conditions with the addition of
    an inhibitor. It must be stored away from substances with which it
    can react, such as halogens, oxidative substances, amines, organic
    substances, caustic solutions, concentrated sulfuric acid.

    4.6  Transport

    In case of an accident, stop the engine. Remove all sources of
    ignition. Keep public away from danger area, mark the roads and keep
    upwind. Use non-sparking handtools and explosion-proof electrical
    equipment. Notify police and fire brigade immediately. In case of
    spillage or fire, follow advice given in sections 4.4 and 4.7,
    respectively. In case of poisoning, follow advice in the Summary of
    Chemical Safety Information (section 6).

    4.7  Spillage

    In case of spillage of acetaldehyde, remove all ignition sources and
    evacuate and ventilate the danger area. Ensure personal protection
    (protective clothing, safety goggles and/or breathing protection),
    and shut off leaks, if without risk. Collect the leaking liquid in
    sealable containers. Absorb the spilt acetaldehyde in sand or an
    inert absorbent and remove to a safe place; DO NOT absorb in sawdust
    or other combustible absorbents. Remove vapour with fine water spray
    and flush contaminated area with plenty of water. Prevent the liquid
    from entering sewers and ditches.

    If acetaldehyde has entered a water course or sewer, or, if it has
    contaminated soil or vegetation, warn police.

    5.  HAZARDS FOR THE ENVIRONMENT AND THEIR PREVENTION

    Acetaldehyde appears to be toxic, even at low concentrations and
    with short periods of exposure, to fungi. It can also inhibit the
    seed germination of several plants.

    Contamination of the environment can be minimized by proper methods
    of storage, handling, transport, and production, and by reducing the
    emission sources (such as open burning, incineration of gas, fuel
    oil, and coal). In case of spillage, apply methods recommended in
    section 4.7.

    6.  SUMMARY OF CHEMICAL SAFETY INFORMATION

    This summary should be easily available to all health workers
    concerned with, and users of, acetaldehyde. It should be displayed
    at, or near, entrances to areas where there is potential exposure to
    acetaldehyde, and on processing equipment and containers. The
    summary should be translated into the appropriate language(s). All
    persons potentially exposed to the chemical should also have the
    instructions in the summary clearly explained.
    Space is available for insertion of the National Occupational
    Exposure Limit, the address and telephone number of the National
    Poison Control Centre, and local trade names.

    
    SUMMARY OF CHEMICAL SAFETY INFORMATION


    ACETALDEHYDE
    CH3CHO; CAS Registry No.75-07-0

                                                                                                                                 
    PHYSICAL PROPERTIES                                                             OTHER CHARACTERISTICS
                                                                                                                                 

    Melting point                         -123.5 C                                 Acetaldehyde is a colourless liquid
    Boiling point at 101.3 kPa            20.2 C                                   with a pungent suffocating odour;
    Water solubility                      completely miscible in water              the odour threshold in air is reported to
    Specific density (20/4)               0.778                                     be 0.09 mg/m3; vapour is heavier than 
    Relative vapour density               1.52                                      air and may spread along the ground and 
    Vapour pressure (20 C)               101.3 kPa                                 be ignited from a distance; the compound
    Autoignition temperature              185-193 C                                may polymerize violently under the 
    Flash point, closed cup               -38 C                                    influence of bases, with fire or explosion
    Relative molecular mass               44.1                                      hazards; acetaldehyde is a strong reducing
    Octanol/water partition                                                         agent and reacts violently with oxidants,
      coefficient (log Pow)               0.63                                      causing fire and explosion hazards

                                                                                                                                 
     HAZARD/SYMPTOM                       PREVENTION AND PROTECTION                 FIRST AID
                                                                                                                                 

    SKIN: corrosive; redness, pain        Wear plastic or synthetic rubber gloves,  Remove soaked clothing, wash the skin with
                                          apron, and boots                          plenty of water; obtain medical attention
                                                                                    immediately

    EYES: corrosive; redness, pain,       Wear safety goggles or face shield in     Wash the eyes with plenty of water; remove
    blurred vision                        combination with breathing protection     contact lenses if easily possible; obtain
                                                                                    medical attention immediately
                                                                                                                                 

                                                                                                                                 
    PHYSICAL PROPERTIES                                                             OTHER CHARACTERISTICS
                                                                                                                                 

    INHALATION: corrosive; sore throat,   Apply ventilation, exhaust hood and/or    Remove victim to fresh air and keep victim
    coughing, pulmonary oedema,           breathing protection                      quiet in half-upright position; obtain
    unconsciousness and effects                                                     medical attention immediately; subcutaneous
    resembling alcoholic intoxication                                               application of -sympathomimetic
                                                                                    substances

    INGESTION: corrosive; abdominal       Do not eat, drink, chew or smoke          Rinse mouth; do not induce vomiting;
    pains, diarrhoea, vomiting, burning   during work; do not keep food in areas    obtain medical attention immediately
    sensation, dizziness, headache,       with potential exposure; keep out of
    nausea, unconsciousness               reach of children

    ENVIRONMENT: toxic to                 Minimize contamination of water, soil
    micro-organisms, inhibits seed        and atmosphere by proper methods of
    germination in plants                 storage, handling, transport, and
                                          production, and by reduction of
                                          emission sources

                                                                                                                                 
    SPILLAGE                              STORAGE                                   FIRE AND EXPLOSION
                                                                                                                                 
    Ensure personal protection; shut      Store in fireproof, dark and cool         Acetaldehyde is highly flammable;
    off leaks, if without risk; remove    conditions with addition of an            avoid open fire or sparks; no smoking
    ignition sources; evacuate and        inhibitor; store separately from          and no naked lights; no contact with
    ventilate area; collect leaking       halogens, oxidative substances,           heated surfaces; in case of fire keep
    liquid in closed containers;          amines, oragnic substances, caustic       containers cool by spraying water;
    absorb spilt acetaldehyde in          solutions, concentrated sulfuric          extinguish fire with chemical powder,
    sand or inert absorbent; remove       acid                                      alcohol-resistant foams, carbon dioxide, a
    vapour with fine water spray and                                                large amount of water; acetaldehyde vapour
    flush area with plenty of water;                                                in air may be explosive; ventilate; use 
    do not let run off into a sewer                                                 non-sparking tools, closed and 
                                                                                    explosion-proof equipment

                                                                                                                                 
    WASTE DISPOSAL
                                                                                                                                 

    Dissolve in a combustible solvent,
    such as alcohol or benzene, then
    spray the solution in the furnace
    with afterburner
    

    7. CURRENT REGULATIONS, GUIDELINES, AND STANDARDS

    7.1  Exposure Limits

    Some exposure limits are given in the table on pages 26-29.

    7.2  Specific Restrictions

    In the USA, no power-operated truck may be used in atmospheres
    where a hazardous concentration of the substance is present.
    Current regulation of the EC:

      Warning signs:         F Easily flammable

      Risk numbers:          12 Extremely flammable

                             36/37 Irritating to eyes and respiratory
                             system

      Safety numbers:        9 Keep container in a well-ventilated
                             place

                             16 Keep away from sources of ignition-no
                             smoking

                             29 Do not empty into drains

                             33 Take precautionary measures against
                             static discharges

    7.3  Labelling, Packaging, and Transport

     United Kingdom

    In the United Kingdom, the labelling of road tankers containing
    acetaldehyde must be: "flammable liquid". Emergency action code:
    2YE.

    For labelling and packaging methods, the United Kingdom refers to
    the EC (OJEC L.106,18,1982).

     Germany

    For labelling and packaging methods, Germany refers also to the
    EC (OJEC L.106,18,1982).


    
    CURRENT REGULATIONS, GUIDELINES, AND STANDARDS


    Exposure limit values
                                                                                                                                 
    Medium       Specification    Country/            Exposure limit description a            Value               Effective
                                                      organization                                                date
                                                                                                                                 

    AIR          Occupational     Argentina           Maximum permissible concentration                           1979
                                                      Time-weighted average (TWA)             180 mg/m3
                                                      Short-term exposure limit (STEL)        270 mg/m3

                                  Australia           Threshold limit value (TLV)                                 1985 (r)
                                                      Time-weighted average (TWA)             180 mg/m3
                                                      Short-term exposure limit (STEL)        270 mg/m3

                                  Belgium             Threshold limit value (TLV)                                 1987 (r)
                                                      Time-weighted average (TWA)             180 mg/m3
                                                      Short-term exposure limit               270 mg/m3

                                  Canada              Threshold limit value (TLV)                                 1980
                                                      Time-weighted average (TWA)             180 mg/m3
                                                      Short-term exposure limit (STEL)        270 mg/m3

                                  Czechoslovakia      Maximum acceptable concentration                            1985
                                                      Time-weighted average (TWA)             200 mg/m3
                                                      Celing limit value (CLV)                400 mg/m3

                                  Finland             Maximum permissible concentration                           1985 (r)
                                                      Time-weighted average (TWA)             90 mg/m3
                                                      Short-term exposure limit (STEL)        135 mg/m3

                                  Germany (former     Threshold limit value (TLV)                                 1987 (r)
                                  FRG)                Time-weighted average (TWA)             90 mg/m3
                                                      Short-term exposure limit (STEL)        180 mg/m3
                                                      (5-min TWA)
                                                                                                                                 

                                                                                                                                 
    Medium       Specification    Country/            Exposure limit description a            Value               Effective
                                                      organization                                                date
                                                                                                                                 

    Air          Occupational     Germany (former     Maximum acceptable concentration                            1988 (r)
                                  GDR)                Short-term exposure limit (STEL)        100 mg/m3

                                  Hungary             Maximum acceptable concentration                            1985 (r)
                                                      Time-weighted average (TWA)             50 mg/m3
                                                      Short-term exposure limit (STEL)        250 mg/m3
                                                      (30 min)

                                  Italy               Treshold limit value (TLV)              100 mg/m3           1985 (r)

                                  Netherlands         Maximum limit (MXL)                                         1987 (r)
                                                      Time-weighted average (TWA)             180 mg/m3

                                  Poland              Maximum permissible concentration                           1985 (r)
                                                      Time-weighted average (TWA)             5 mg/m3

                                  Romania             Maximum permissible concentration                           1985 (r)
                                                      Time-weighted average (TWA)             100 mg/m3
                                                      Ceiling limit value (CLV)               200 mg/m3

                                  Sweden              Hygienic limit value                                        1988
                                                      Time-weighted average (TWA)             45 mg/m3
                                                      Short-term exposure limit (STEL)        90 mg/m3

                                  Switzerland         Maximum work-site concentration                             1987 (r)
                                                      Time-weighted average (TWA)             90 mg/m3

                                  United Kingdom      Recommended limit (RECL)                                    1987 (r)
                                                      Time-weighted average (TWA)             180 mg/m3
                                                      Short-term exposure limit (STEL)        270 mg/m3

                                  USA                 Permissible exposure limit (PEL)                            1987 (r)
                                                      Time-weighted average (TWA)             360 mg/m3
                                                                                                                                 

                                                                                                                                 
    Medium       Specification    Country/            Exposure limit description a            Value               Effective
                                                      organization                                                date
                                                                                                                                 

    Air          Occupational     USA (ACGIH)         Threshold limit value (TLV)                                 1987 (r)
                                                      Time-weighted average (TWA)             180 mg/m3
                                                      Short-term exposure limit (STEL)        270 mg/m3

                                  former USSR         Maximum acceptable concentration                            1982 (r)
                                                      Ceiling limit value (CLV)               5 mg/m3             1977



    AIR          Ambient,         former USSR         Maximum acceptable concentration                            1984
                  background                          1 /day                                 0.01 mg/m3
                                                      average/day                             0.01 mg/m3

                 Emission         Germany (former     Maximum limit (MXL)                     0.15 mg/m3          1986
                                  FRG)

                                  Japan               Maximum limit (MXL)                     0.09-0.9 mg/m3      1982 (r)
                                                      emmision standard because of
                                                      offensive odour

    WATER        Surface          former USSR         Maximum acceptable concentration        0.2 mg/litre        1983

    SOIL                          former USSR         Maximum acceptable concentration        10 mg/kg            1985
                                                                                                                                 

               

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

    The substance is classified as harmful to water (class 2). In order
    to protect water, appropriate security measures should be taken
    during storage, loading, and transport.

     United States of America

    In the USA, acetaldehyde, when carried in bulk, is classified as a
    "cargo of particular hazard" for purposes of regulations governing
    handling of dangerous cargoes in, or contiguous to, waterfront
    facilities. A permit is required for handling such cargo.

    Unless in compliance with a specified procedure, owners/operators of
    vessels, or on- or offshore facilities must notify the US Government
    of any discharge of this substance in, or on, navigable waters,
    adjoining shorelines or the contiguous zone in an amount equal to,
    or greater than, 45 kg in any 24-h period. Such a discharge is a
    violation of the Federal Water Pollution Control Act. When certain
    specified vessels carrying acetaldehyde in bulk are bound for
    departure from the US ports, the captain of the port must be
    notified at least 24 h in advance.

     Canada

    Acetaldehyde is hazardous to the environment. The maximum amount per
    package that may be transported on a cargo aircraft: 30 litres.

    7.4  Discharges, Waste Disposal

    In the USA, a permit is required for the discharge of any pollutant
    from any point source into US waters. The following must report
    quantitative data for the substance in their applications: every
    applicant who has reason to believe that the substance is contained
    in any of his outfalls inspection, monitoring and reporting
    requirements after the issue of the permit are specified. Even if
    not required in the permit, discharge of the substance must be
    reported if it exceeds the highest of the following levels: (a) 100
    mg/litre, (b) 5 times the maximum concentration reported in the
    application, (c) the level established by the director of the
    Environmental Protection Agency.

    In the USA, acetaldehyde, including any isomers, hydrates, and
    solutions and mixtures containing the substance, is designated as a
    hazardous substance for the purposes of discharge (including
    spilling, leaking, etc.) under the water pollution control act.

    Acetaldehyde, if it is a commercial chemical product, is identified
    in the USA as a "toxic waste" subject to regulation and notification
    requirements.

    BIBLIOGRAPHY

    CEFIC (1979) Transport Emergency Cards for Individual Products.
    CEFIC TEC(R)-620. London & Tonbridge, Whitefriars Press Ltd.

    The Association of the Dutch Chemical Industry (1989) [Chemical
    cards. Data for working safely with chemicals.] 5th ed. Alphen aan
    den Rijn, Samson HD Tjeenk Willink (in Dutch).

    Henschler D (1992) [Hazardous occupational materials. Toxicological
    basis of exposure limits.] Weinheim: VCH Verlagsgesellschaft mbH, pp
    1-3 (in German).

    IARC (1985) Allyl compounds, aldehydes, epoxides and peroxides.
    Lyon, International Agency for Research on Cancer, pp 101-132 (IARC
    Monographs on the evaluation of carcinogenic risk of chemicals to
    humans, Vol. 36).

    IPCS/CEC (1990) International chemical safety card No. 0009:
    Acetaldehyde. Luxembourg, Commission of the European Communities.

    IRPTC (1992) Legal file 1992. Geneva, International Register of
    Potentially Toxic Chemicals/UNEP.

    Sittig M (1979) Hazardous and Toxic Effects of Industrial Chemicals.
    Park Ridge, Noyes Data Corporation, pp 1-3.

    WHO (in preparation) Environmental Health Criteria 167:
    Acetaldehyde. Geneva, World Health Organization.


    See Also:
       Toxicological Abbreviations
       Acetaldehyde (EHC 167, 1995)
       Acetaldehyde (ICSC)
       ACETALDEHYDE (JECFA Evaluation)
       Acetaldehyde (IARC Summary & Evaluation, Volume 71, 1999)