Health and Safety Guide No. 58






    This is a companion volume to Environmental Health Criteria 117:
    Methyl isobutyl ketone

    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

    Methyl isobutyl ketone : health and safety guide.

    (Health and safety guide ; no. 58)

    1. Ketones - standards  I. Series

    ISBN 92 4 151058 7          (NLM Classification: QV 633)
    ISSN 0259-7268

    (c) World Health Organization 1991

    Publications of the World Health Organization enjoy copyright
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    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

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    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.



         1.1. Identity
         1.2. Physical and chemical properties
         1.3. Analytical methods
         1.4. Uses

         2.1. Human exposure to MIBK
         2.2. Uptake, metabolism, and excretion
         2.3. Effects on animals
         2.4. Effects on human beings


         4.1. Main human health hazards, prevention and protection, first
              4.1.1. Advice to physicians
             Symptoms of poisoning
             Medical advice
              4.1.2. Health surveillance advice
         4.2. Safety in use
         4.3. Explosion and fire hazards
              4.3.1. Flammability and explosion
              4.3.2. Fire
         4.4. Storage
         4.5. Transport
         4.6. Spillage and disposal
              4.6.1. Spillage
              4.6.2. Disposal



         7.1. Regulation of emissions
         7.2. Regulation of food and food wrappings
         7.3. Regulation of beverages
         7.4. Exposure limit values
         7.5. Labelling and packaging



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



    1.1  Identity

    Common name:                  methyl isobutyl ketone (MIBK)

    Chemical structure
                                   CH3 - C - CH2 - CH
                                         "          '
                                         O         CH3

    Chemical formula:             C6H12O

    Relative molecular mass:      100.16

    CAS chemical name:            4-methyl-2-pentanone

    CAS registry number:          108-10-1

    RTECS registry number:        SA9275000

    Purity:                       MIBK is typically 99% (w/w) pure. 
                                  Impurities that may be present include:
                                  dimethyl heptane (0.3%), water (0.1%),
                                  methyl isobutyl carbinol (0.06%),
                                  mesityl oxide (0.03%), acetic acid
                                  (0.002%), and non-volatile components

    1.2  Physical and Chemical Properties

    MIBK is a clear liquid with a sweet odour; the odour threshold is
    1.64 mg/m3 (0.4 ppm).  It is moderately soluble in water.

    Some physical and chemical properties of MIBK are given in the Summary
    of Chemical Safety Information (section 6).

    MIBK can react violently with oxidizing and reducing agents.  When
    heated, peroxides may form by auto-oxidation and may explode

    1.3  Analytical Methods

    Gas chromatography combined with flame ionization or mass spectroscopy
    is a suitable technique for the determination of MIBK, which can be
    detected in air (by trapping with, e.g., charcoal), in water (e.g.,
    headspace or extraction), and in biological tissues (e.g., headspace
    or extraction).

    1.4  Uses

    MIBK, which occurs naturally in food, is a permitted flavouring agent
    and is used in food-contact materials.  It is a component of cellulose
    and polyurethane lacquers and paint solvents.  It is also used: as an
    extraction solvent; in the manufacture of methyl amyl alcohol; and as
    a denaturant for ethyl alcohol.


    2.1  Human Exposure to MIBK

    The general population is exposed to low levels of MIBK, which has
    been detected in certain foods at levels in the mg/kg range.  Two
    countries have  established maximum ambient air concentrations in the
    range of 0.1-0.2 mg/m3 for general population exposure.

    Occupational exposure occurs particularly in the production and use of
    lacquers, paints, and extraction solvents.  The major route of
    exposure is inhalation.

    2.2  Uptake, Metabolism, and Excretion

    MIBK is absorbed in animals via inhalation, ingestion, and through the
    skin. It is widely distributed throughout the body.  MIBK is readily
    metabolized to water-soluble excretory products and can induce
    metabolic activation in the liver.  The urine is the major route of
    excretion for metabolites.

    2.3  Effects on Animals

    In animal studies, the acute systemic toxicity of MIBK, via the oral
    and inhalation routes of exposure, is low.  In a 90-day gavage study
    on rats, a no-observed-effect level (NOEL) of 50 mg/kg per day was
    found.  In 90-day inhalation studies on rats and mice, concentrations
    of up to 4100 mg/m3 (1000 ppm) did not result in significant
    toxicity, though compound-related reversible morphological changes
    were reported in the liver and kidney.  Evidence of central nervous
    system depression was seen in animals exposed to a level of
    4100 mg/m3 (1000 ppm).  In a number of studies, exposure to MIBK
    concentrations as low as 1025 mg/m3 (250 ppm) resulted in an
    increase in liver size and induced hepatic microsomal metabolism. 
    This may be responsible for the exacerbation of haloalkane toxicity
    and for the potentiation of the neurotoxicity of  n-hexane.  MIBK was
    also found to potentiate the cholestatic effects of manganese given
    with, or without, bilirubin.  In 90-day studies on mice, rats, dogs,
    and monkeys, only male rats developed hyaline droplets in the proximal
    tubules of the kidney.  Effects on behaviour were reported in baboons
    exposed for 7 days to 205 mg/m3 (50 ppm).

    At a concentration of 4100 mg/m3 (1000 ppm), MIBK was not
    embryotoxic, fetotoxic, or teratogenic in rats or mice.  Fetotoxicity
    was only observed at concentrations of MIBK that caused maternal

    MIBK did not induce gene mutations in  in vitro bacterial test
    systems with, or without, metabolic activation.  Negative results were
    also obtained  in vitro with, or without, metabolic activation, in
    tests for mitotic gene conversion in yeast, and for gene mutation in
    cultured mammalian cells.  The results of  in vitro assays for

    unscheduled DNA synthesis in primary rat hepatocytes and for
    structural chromosome damage in cultured rat liver cells were
    negative.  An  in vivo micronucleus test on mice was negative.  These
    data indicate that MIBK is not genotoxic.  No long-term or
    carcinogenicity studies are available.

    The toxicity of MIBK for aquatic organisms and microorganisms is low.

    2.4  Effects on Human Beings

    The low odour threshold (1.64 mg/m3) and the irritant effects can
    provide warning of high concentrations.  Exposure to levels of
    10-410 mg/m3 (2.4-100 ppm) produced perceptible irritation of the
    eyes, nose, or throat, and 820 mg/m3 (200 ppm) produced discomfort. 
    Symptoms, such as headache, nausea, or vertigo, also occurred at
    10-410 mg/m3 (2.4-100 ppm).  A 2-h exposure of up to 200 mg/m3
    (50 ppm) did not produce any significant effects on a simple
    reaction-time task or a test of mental arithmetic.


    Because of the irritant effects of MIBK, contact with the skin and
    eyes should be avoided.  Ingestion of MIBK should not occur with good
    practices; workers who come into contact with MIBK should not be at
    risk, provided that exposure levels in the workplace are kept as low
    as possible and within the prescribed control limits.

    The half-life of MIBK in the environment is short and its toxicity for
    aquatic organisms is low.  Consequently, there is no risk for the
    environment, provided that there are adequate controls on disposal.


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

    MIBK causes eye and respiratory tract irritation and has reversible
    depressant effects on the central nervous system.

    The hazards can be avoided by taking the appropriate precautions and
    by controlling exposure.

    4.1.1  Advice to physicians  Symptoms of poisoning

    Symptoms and signs include: irritation of the eyes, skin, and
    respiratory tract, and depression of the central nervous system,
    manifested by headaches, nausea, and narcosis.  Gastrointestinal pain
    and hepatic toxicity may occur with exposure to high concentrations.  Medical advice

    In case of poisoning by MIBK, contact the nearest Poisons Information
    Centre for detailed advice on treatment.  Information on first aid is
    provided in the Summary of Chemical Safety Information.  If breathing
    ceases or becomes weak and irregular, artificial respiration should be
    applied and oxygen administered.  If there has been ingestion,
    vomiting should not be induced, because of the risk of aspiration into
    the lungs and the production of chemical pneumonitis.  Gastric lavage
    can be given if a cuffed endotracheal tube is used.

    4.1.2  Health surveillance advice

    A pre-employment medical examination is advised for workers who will
    be regularly exposed to MIBK.  If routine medical checks are
    undertaken, emphasis should be placed on examination of the central
    nervous system, respiratory tract, gastrointestinal tract, and skin.

    4.2  Safety in Use

    Air levels should be kept as low as practicable using suitably
    designed plant and engineering controls, such as local exhaust
    ventilation.  Respiratory protection should be readily available for
    use in enclosed spaces, and for certain maintenance operations. 
    Self-contained breathing apparatus should be available for use in
    emergencies.  Skin and eye protection is recommended, when exposure to
    liquid MIBK is likely to occur.

    4.3  Explosion and Fire Hazards

    4.3.1  Flammability and explosion

    MIBK is highly flammable and adequate ventilation should be provided. 
    Smoking should be prohibited and electrical equipment should be
    designed to a recognized, explosion-proof standard.

    4.3.2  Fire

    Fire extinguishers containing carbon dioxide, dry powder, or foam are
    recommended.  Flashback along a vapour trail may occur.  Water should
    not be used, since this may cause the fire to spread, though a water
    spray can be used to cool containers.

    4.4  Storage

    Drums should be stored in a well-ventilated area away from sources of
    ignition and heat.  The storage temperature should not exceed 40C.

    4.5  Transport

    Comply with national and international requirements regarding the
    transport of hazardous material.  Containers should be in good
    condition and properly labelled.  Keep containers in a well-ventilated
    place, away from sources of ignition.  When pumping, the flow of MIBK 
    may generate electrostatic charges and, therefore, all equipment
    should be earthed.

    4.6  Spillage and Disposal

    4.6.1  Spillage

    In the event of spillage, naked flames, sparks, and heat should be
    avoided.  Contact with skin and eyes should be avoided by wearing
    suitable protective gloves, face-shield and boots.  Liquid should be
    prevented from entering drains and sewers.  Spillages (small-scale)
    should be absorbed on paper towels, sawdust, or sand, and all material
    should be removed to a safe place for subsequent disposal.

    4.6.2  Disposal

    The International Register of Potentially Toxic Chemicals recommends:

    "Incineration, open burning, use as a boiler fuel. Spray into the
    furnace.  Incineration will become easier by mixing with a more
    flammable solvent."


    Industrial discharges from the manufacture, formulation, and technical
    applications of MIKB should be controlled.

    MIBK has a short half-life in the atmosphere and is also biodegraded
    in water.  It is not expected to bioaccumulate.

    The toxicity of MIBK for microorganisms and aquatic organisms is low.


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


    CAS name: 4-methyl-2-pentanone         Chemical formula: C6H12O

    CAS registry number: 108-10-1          RTECS registry number: SA9275000


    PHYSICAL PROPERTIES                                                   OTHER CHARACTERISTICS

    Boiling point (C)                  116                                Colourless, volatile liquid with a sweet odour;
    Freezing point (C)                 -80                                odour threshold approximately 1.6 mg/m3 (0.4 ppm)
    Specific gravity (20C/4C)        0.8017
    Vapour pressure (KPa; 20C)        1.99
    Relative molecular mass            100.16
     n-Octanol/water partition
      coefficient (low Pow)            1.38
    Solubility in water
      (g/litre; 20C)                  17
    Vapour density (air = 1)           3.45
    Autoignition temperature (C)      460
    Explosion limits in air
      (% by volume)                    1.4-7.5
    Closed-cup flashpoint (C)         14


    HAZARDS/SYMPTOMS                        PREVENTION AND PROTECTION                    FIRST AID


    SKIN: MIBK liquid may irritate          Avoid skin contact; wear protective          Remove from exposure; remove contaminated
    the skin, when in close contact;        clothing                                     clothing; wash skin thoroughly with soap
    repeated contact may produce                                                         and plenty of water
    dermatitis because of its defatting

    EYES: Undiluted MIBK is an              Wear face-shield or goggles                  Remove from exposure; irrigate the eyes
    irritant; high vapour concentrations                                                 thoroughly with water or eyewash solution for
    are irritant                                                                         15 minutes; obtain medical attention

    INHALATION: MIBK at high                Control work environment to within           Remove patient to fresh air and keep warm;
    concentrations is a respiratory         recommended exposure limit;                  if breathing has stopped, apply artificial
    irritant; it may cause depression       otherwise provide respiratory                respiration;  obtain medical attention
    of the central nervous system,          protection, such as a respirator
    such as dizziness, fatigue, and 

    INGESTION: should not occur             Do not eat, drink, or smoke during           Rinse mouth; vomiting should not be induced;
    with good work practices                work                                         keep patient warm and rested; obtain medical

    ENVIRONMENT: half-life in               Industrial discharges should be
    the environment is short; low           minimized and regulated;
    toxicity for microorganisms and         disposal should only be via
    aquatic organisms; should not           incineration
    pose a risk, provided there are
    adequate controls to minimize 

    SPILLAGE                                STORAGE                                      FIRE AND EXPLOSION

    Take appropriate personal               Store drums in a well-ventilated             Adequate ventilation should be provided
    precautions; absorb spillage on         area in fire-resistant containers;           and there should be no sources of sparks,
    paper towel, sawdust, or sand, for      metal containers should be                   heat, or naked flames; flashback along a
    subsequent action; avoid spills         electrically-grounded, when                  vapour trail may occur; fire extinguishers
    entering drains or surface waters       transferring liquid                          containing carbon dioxide, dry powder,
                                                                                         or foam are recommended; water sprays
                                                                                         should not be used, except to cool containers


    WASTE DISPOSAL                                                                       LABELLING

    Waste material should be                National Occupational Exposure               United Nations 1245
    incinerated in an approved              Limit:                                       Hazard Class 3 (flammable liquid)
    manner                                                                               Packing Group III (medium danger)
                                            National Poison Control Centre:

                                            Local trade names:



    The information given in this section has been extracted from the
    International Register of Potentially Toxic Chemicals (IRPTC) legal
    file. A full reference to the original national document from which
    the information was extracted can be obtained from IRPTC.  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).

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

    7.1  Regulation of Emissions

    In the Federal Republic of Germany, MIBK belongs to Class III, the air
    emissions of which must not exceed (as the sum of all compounds in any
    class) 150 mg/m3 (37 ppm), at a mass flow of > 3 kg/h.  The
    maximum recommended ambient concentration is 0.2 mg/m3 (0.05 ppm) in
    Czechoslovakia, and it must not exceed 0.1 mg/m3 (0.025 ppm) in the

    7.2  Regulation of Food and Food Wrappings

    MIBK is allowed as a component of food-packaging materials in the EEC
    and in the USA.

    7.3  Regulation of Beverages

    The Council of Europe Committee of Experts on Flavouring Substances
    suggested a limit of 5 mg/litre in beverages.

    7.4  Exposure Limit Values

    Some occupational air exposure limit values are given in the table on
    pages 24-26.

    7.5  Labelling and Packaging

    The United Nations recommends labelling as Hazard Class 3 (flammable
    liquid), Packing Group III (medium danger).

    In the European Economic Community, MIBK is labelled as follows:

          Highly flammable, keep container in a well-ventilated place,
          keep away from sources of ignition, no smoking, do not breathe
          gas/fumes/vapour spray.  Take precautionary measures against
          static discharges.



    Country/               Exposure limit descriptiona                          Value              Effective
    organization                                                                (mg/m3)            dateb

    Australia              Recommended threshold limit value (TLV)
                           -Time weighted average (TWA)                         205                1983(r)
                           -Short-term exposure limit (STEL)                    300

    Belgium                Recommended threshold limit value (TLV)
                           -Time weighted average (TWA)                         205                1988(r)
                           -Short-term exposure limit (STEL)                    300

    Finland                Permissible exposure limit (MPC)
                           -Time weighted average(TWA)                          210                1987
                           -Short-term exposure limit (STEL)                    315

    Germany (Federal       Recommended threshold limit value (MAK)
    Republic of)           -Time weighted average (TWA)                         400                1988(r)
                           -Short-term exposure limit (STEL)                    2000

    Japan                  Administrative concentration
                           -Time weghted average (TWA)                          205                1990(n)

    Netherlands            Recommended threshold limit value (MXL)
                           -Time weighted average (TWA)                         240                1989(r)

    Poland                 Permissible exposure limit (MPC)
                           -Time weighted average (TWA)                         200                1982(r)

    Romania                Permissible exposure limit (MPC)
                           -Time weighted average (TWA)                         200                1984(r)
                           -Ceiling value (CLV)                                 300

    Switzerland            Permissible exposure limit (MAK)
                           -Time weighted average (TWA)                         205                1987(r)


    Country/               Exposure limit descriptiona                          Value              Effective
    organization                                                                (mg/m3)            dateb

    Sweden                 Permissible exposure limit (HLV)
                           -Time weighted average (TWA)                         100                1990(n)
                           -Short-term exposure limit (STEL)                    200

    United Kingdom         Occupational exposure standard (OES)
                           -Time weighted average (TWA)                         205                1990(n)
                           -Short-term exposure limit (STEL)                    300

    USA (ACGIH)            Recommended threshold limit value (TLV)
                           -Time weighted average (TWA)                         205                1989
                           -Short-term exposure limit (STEL)                    307

    USA (OSHA)             Permissible exposure limit (PEL)
                           -Time weighted average (TWA)                         410                1974

    USSR                   Temporary exposure limit (TSEL)
                           -Ceiling value (CLV)                                 5                  1989

    Yugoslavia             Permissible exposure limit (MAC)
                           -Time weighted average (TWA)                         410                1971(r)


    a TWA = a maximum mean exposure limit, generally, over the period of a working day.
      STEL = a maximum concentration of exposure for a specified time duration (generally 10-30 min).
    b n = Notified direct by country.


    ACGIH (1986)  Documentation of the threshold limit values and
     biological exposure indices. Cincinnati, American Conference of
    Governmental Industrial Hygienists.

    ACGIH (1989)  Threshold limit values and biological exposure indices
     for 1989-1990. Cincinnati, American Conference of Governmental
    Industrial Hygienists.

    CLAYTON, G.D. & CLAYTON, F.E. (1981)  Patty's industrial hygiene and
     toxicology. Vol. 2 C.  New York, Wiley-Interscience, John Wiley &

    GOSSELIN, R.E., HODGE, H.C., SMITH R.P., & GLEASON, M.N. (1976)
     Clinical toxicology of commercial products. 4th ed. Baltimore,
    Maryland, The Williams and Wilkins Company.

    HANDLING CHEMICALS SAFELY (1989)  Handling chemicals safely. 2nd ed.
    Dutch Association of Safety Experts, Dutch Chemical Industry
    Association, Dutch Safety Institute.

    IRPTC (1988)  Data profile (legal file).  Geneva, International
    Register of Potentially Toxic Chemicals.

    SAX, N.I. (1984)  Dangerous properties of industrial materials. New
    York, Van Nostrand Reinhold Company.

    US NIOSH (1976)  A guide to industrial respiratory protection. 3 Vol.
    Cincinnati, Ohio, US National Institute for Occupational Safety and
    Health. Occupational Safety and Heath Administration, 

    US NIOSH/OSHA (1981)  Occupational health guidelines for chemical
     hazards. 3 Vol. Washington, DC, US Department of Health and Human
    Services, US Department of Labor (Publication No. DHHS(NIOSH) 81-123).

    US NIOSH/OSHA (1985)  Pocket guide to chemical hazards.  Washington
    DC, US National Institute for Occupational Safety and Health,
    Occupational Safety and Heath Administration (Publication No. 85.114).

    WHO (1990)  Environmental Health Criteria 117: Methyl isobutyl ketone.
    Geneva, World Health Organization.


    See Also:
       Toxicological Abbreviations
       Methyl isobutyl ketone (EHC 117, 1990)
       Methyl isobutyl ketone (ICSC)