Air toxics and indoor air quality in Australia

State of knowledge report
Environment Australia, 2001
ISBN 0 6425 4739 4

Part C: Factsheets (continued)

Methyl isobutyl ketone

Substance name: Methyl isobutyl ketone
CASR number: 108-10-1
Molecular formula: C6H12O
Synonyms: Hexone; 4-methyl-2-pentanone; isobutyl methyl ketone; MIBK; 4-methylpentan-2-one; MIK; 2-methyl-4-pentanone; isohexanone

Physical and chemical properties

Methyl isobutyl ketone is a colourless liquid with a faint odour like camphor.

Melting point: -84.7°C
Boiling point: 117.6C
Vapour density: 3.5
Specific gravity: 0.7978
Flashpoint: 17°C

Methyl isobutyl ketone is a flammable liquid. It is partially soluble in water.

Common uses

Methyl isobutyl ketone is used as a solvent for manufacturing paints, rubbers, pharmaceuticals, chemicals and machinery. It is used in the semiconductor industry, the fragrance and flavour industries, as a drycleaning agent and in uranium extraction. It has been used as a pesticide.

Sources of emissions

Point sources

The primary sources of methyl isobutyl ketone are the industries that manufacture it or use it in production. These include the chemical industry, rubber manufacturers, the pharmaceutical industry, the semiconductor industry, manufacturers of millwork, veneer and plywood and manufacturers of paints, varnishes and lacquers.

Diffuse sources, and point sources included in aggregated emissions data

Other possible emitters of methyl isobutyl ketone are commercial and household painting and paint, varnish and lacquer removal, drycleaners and consumer products containing methyl isobutyl ketone.

Natural sources

Methyl isobutyl ketone is found in oranges, grapes and vinegar.

Mobile sources

There are no known mobile sources of methyl isobutyl ketone.

Consumer products that may contain methyl isobutyl ketone

Products include aerosol paints, architectural coatings, automobile and machinery paints and primers, household hard surface cleaners, household dyes and tints, insecticides for yard and garden, laundry starches, lubricating greases and oils, automotive chemicals, paints, varnish and paint and varnish removers and thinners, pet flea and tick products, shoe polish, interior clear finishes, undercoats, and primers, and wood office furniture.

Health effects

How might I be exposed to methyl isobutyl ketone?

Workers in the industries that use or produce methyl isobutyl ketone are at risk of exposure. Consumers can be exposed to methyl isobutyl ketone by exposure to air from production and processing facilities that use methyl isobutyl ketone. Consumers may also be exposed when using consumer products containing methyl isobutyl ketone, especially if there is not good ventilation. Methyl isobutyl ketone is used in many consumer products and short-term indoor concentrations may be elevated above the levels considered safe for workers.

By what pathways might methyl isobutyl ketone enter my body?

Methyl isobutyl ketone will enter the body if we breathe in contaminated air, or consume food or water that has been contaminated. It can also pass through the skin.

Health guidelines

National Occupational Health and Safety Commission (NOHSC):

The NOHS lists methyl isobutyl ketone as a substance under review regarding skin absorption.

What effect might methyl isobutyl ketone have on my health?

Breathing methyl isobutyl ketone for short periods of time (eg painting in a poorly ventilated area) can affect the nervous system. Effects include headaches, dizziness, narcosis (acts like a narcotic), nausea, numbness in the fingers and toes, and (if the exposure is prolonged) unconsciousness, and even death. Methyl isobutyl ketone vapour irritates the eyes, nose, and throat. Prolonged contact with the skin causes irritation.

Environmental effects

Environmental fate

Methyl isobutyl ketone quickly evaporates to a gas if released as a liquid. It dissolves when mixed with water. It evaporates from both water and soil when exposed to air. It will quickly break down in the air into acetone, formaldehyde, and 2-methylpropanal. In the soil and water, bacteria break it down.

Environmental transport

Industrial emissions of methyl isobutyl ketone can produce elevated, but still low-level, concentrations in the atmosphere around the source. However, because of its short life-expectancy in the atmosphere, methyl isobutyl ketone is expected to be confined to the local area in which it is emitted. Since it does not bind well to soil, methyl isobutyl ketone that makes its way into the ground may move through the ground and enter groundwater (bore water).

Environmental guidelines

There are no national guidelines.

What effect might methyl isobutyl ketone have on the environment?

Methyl isobutyl ketone has slight acute (short-term) and chronic (long-term) toxicity to aquatic life. It has high toxicity to birds. Chronic and acute effects on plants or land animals have not been determined. Methyl isobutyl ketone is not expected to bioaccumulate.


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