Methyl isobutyl ketone [factsheet]

METHYL ISOBUTYL KETONE

Please Note: The main source of information for this fact sheet is EPA's Health Effects Assessment for Methyl Isobutyl Keone. Other secondary sources include the Hazardous Substances Data Bank (HSDB), a database of summaries of peer-reviewed literature, and the Registry of Toxic Effects of Chemical Substances (RTECS), a database of toxic effects that are not peer reviewed.

Environmental/Occupational Exposure

* Exposure may occur in the workplace by the inhalation of vapors and by skin and eye contact. (1)

* The most probable routes of exposure to methyl isobutyl ketone by the general population are by inhalation and dermal contact during the use of consumer products that contain this compound. (1)

* Methyl isobutyl ketone may be released to the environment in effluent and emissions from its manufacture and use, in exhaust gas from vehicles, and from land disposal and ocean dumping of waste that contains this compound. Since methyl isobutyl ketone is a solvent and denaturant with a wide variety of applications, a large number of industries could potentially release this compound. Some segments of the population may be exposed by the inhalation of contaminated air or by the ingestion of contaminated drinking water. (1)

Assessing Personal Exposure

* No information was located regarding the measurement of personal exposure to methyl isobutyl ketone.

Health Hazard Information

Acute Effects:

* Acute (short-term) exposure to methyl isobutyl ketone may irritate the eyes and mucous membranes and cause weakness, headache, nausea, lightheadedness, vomiting, dizziness, incoordination, narcosis, and, at high levels, coma and death in humans. (1-4)

* Acute animal tests, such as the LC₅₀ and LD₅₀ tests in rats, mice, rabbits, and guinea pigs, have demonstrated methyl isobutyl ketone to have low acute toxicity by inhalation or dermal exposure and moderate acute toxicity by ingestion. (5)

Chronic Effects (Noncancer):

* Chronic (long-term) occupational exposure to methyl isobutyl ketone has been observed to cause nausea, headache, burning in the eyes, weakness, insomnia, intestinal pain, and slight enlargement of the liver in humans. (4)

* Lethargy and increased kidney and liver weights have been observed in rats and mice chronically exposed by gavage (experimentally placing the chemical in the stomach), ingestion, and inhalation. (4)

* The RfC and the RfD for methyl isobutyl ketone are under review by EPA. (6)

* EPA has calculated a provisional RfD of 0.05 mg/kg/d for methyl isobutyl ketone. (7)

* EPA's Office of Air Quality Planning and Standards, for a hazard ranking under Section 112(g) of the Clean Air Act Amendments, has evaluated methyl isobutyl ketone for chronic toxicity and has given it a composite score of 4 (scores range from 1 to 100, with 100 being the most toxic). These scores are nonlinear and are the product of two ratings: a rating based on the minimal-effect-dose and a rating based on the type of effect. (8)

Reproductive/Developmental Effects:

* No information is available on the reproductive or developmental effects of methyl isobutyl ketone in humans. (4)

* Maternal toxicity and neurological effects and increased liver and kidney weights in fetuses were observed in rats and mice exposed to methyl isobutyl ketone by inhalation. (4)

Cancer Risk:

* No information is available on the carcinogenic effects of methyl isobutyl ketone in humans. (4)

* EPA has classified methyl isobutyl ketone as a Group D, not classifiable as to human carcinogenicity. (4)

Physical Properties

* The chemical formula for methyl isobutyl ketone is C₆H₁₂O, and its molecular weight is 100.16 g/mol. (9)

* Methyl isobutyl ketone occurs as a colorless, flammable liquid that is moderately soluble in water. (3,9)

* Methyl isobutyl ketone has a faint ketonic and camphor odor, with an odor threshold of 0.10 ppm. (1,9)

* The vapor pressure for methyl isobutyl ketone is 15 mm Hg at 20 EC, and its log octanol/water partition coefficient (log K_ow) is 1.09. (4)

Uses

* Methyl isobutyl ketone is used as a solvent for gums, resins, paints, varnishes, lacquers, and nitrocellulose, as an alcohol denaturant, in the extraction of rare metals, and as a synthetic flavoring adjuvant. (1,3,9)

Health Data from Inhalation Exposure

Concentration (mg/m³)	Health numbers^a	Regulatory, advisory numbers^b	Reference
1,000,000.0
_ _ _ _ 100,000.0
_ _ _ _ 10,000.0	* LC₅₀ (mice) (23,300 mg/m³)		5
_ _ _ _ 1,000.0
_ _ _ _ 100.0		* MSHA standard (410 mg/m³) * ACGIH TLV, NIOSH REL and OSHA PEL (205 mg/m³)	5 5

ACGIH TLVCAmerican Conference of Governmental and Industrial Hygienists' threshold limit value expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effects.

LC₅₀ (Lethal Concentration₅₀)CA calculated concentration of a chemical in air to which exposure for a specific length of time is expected to cause death in 50% of a defined experimental animal population.

MSHACMine Safety and Health Administration.

NIOSH RELCNational Institute of Occupational Safety and Health's recommended exposure limit; NIOSH-recommended exposure limit for an 8- or 10-h time-weighted-average exposure and/or ceiling.

OSHA PELCOccupational Safety and Health Administration's permissible exposure limit expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effect averaged over a normal 8-h workday or a 40-h workweek.

^a Health numbers are toxicological numbers from animal testing or risk assessment values developed by EPA.

^b Regulatory numbers are values that have been incorporated in Government regulations, while advisory numbers are nonregulatory values provided by the Government or other groups as advice.

References

1. U.S. Department of Health and Human Services. Hazardous Substances Data Bank (HSDB, online database). National Toxicology Information Program, National Library of Medicine, Bethesda, MD. 1993.

2. E.J. Calabrese and E.M. Kenyon. Air Toxics and Risk Assessment. Lewis Publishers, Chelsea, MI. 1991.

3. M. Sittig. Handbook of Toxic and Hazardous Chemicals and Carcinogens. 2nd ed. Noyes Publications, Park Ridge, NJ. 1985.

4. U.S. Environmental Protection Agency. Health Effects Assessment for Methyl Isobutyl Ketone. EPA/600/8-88/045. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1988.

5. U.S. Department of Health and Human Services. Registry of Toxic Effects of Chemical Substances (RTECS, online database). National Toxicology Information Program, National Library of Medicine, Bethesda, MD. 1993.

6. U.S. Environmental Protection Agency. Integrated Risk Information System (IRIS) on Methyl Isobutyl Ketone. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1993.

7. U.S. Environmental Protection Agency. Health Effects Assessment Summary Tables. Annual Update. OHEA-ECAO-CIN-909. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1993.

8. U.S. Environmental Protection Agency. Technical Background Document to Support Rulemaking Pursuant to the Clean Air ActCSection 112(g). Ranking of Pollutants with Respect to Hazard to Human Health. EPAB450/3-92-010. Emissions Standards Division, Office of Air Quality Planning and Standards, Research Triangle Park, NC. 1994.

9. The Merck Index. An Encyclopedia of Chemicals, Drugs, and Biologicals. 11th ed. Ed. S. Budavari. Merck and Co. Inc., Rahway, NJ. 1989.