Toxicity Profiles

RAGs A Format for Methyl Isobutyl Ketone - CAS Number 108101

Methyl isobutyl ketone (MIBK), also known as 4-methyl-2-pentanone, is a clear liquid with a characteristic ketone odor. It is widely used as a solvent for synthetic resinous paints; lacquers; varnishes; adhesives; rubber cements; and DDT. As an extractant, it is used in dewaxing mineral oils, refining tall oil, and cleaning metals. MIBK is released to the environment in effluents and emissions from its manufacturing and use facilities, in automotive exhaust gases, and from disposal of consumer products containing MIBK.

MIBK is readily absorbed following inhalation and, by analogy to other ketones, is expected to be absorbed through the skin. Targets for MIBK toxicity appear to be the central nervous system, digestive tract, liver, kidneys, fetus, and mucous membranes. At high concentrations, MIBK is a central nervous system depressant, inducing ataxia, narcosis, and death in experimental animals. Human exposure to lower concentrations has resulted in central nervous system effects such as headache, weakness, vertigo, insomnia, and somnolence. Digestive effects include nausea, vomiting, loss of appetite, heart burn, and intestinal pain.

No studies were available to evaluate the carcinogenicity of MIBK. Furthermore, EPA has not assigned a weight-of-evidence classification for carcinogenicity.

The following is a presentation of the toxicity information associated with Methyl Isobutyl Ketone.

Noncarcinogenic Health Effects
  • The Oral Chronic Reference Dose is 8.00E-02 (mg/kg-day).
  • The Oral Chronic Reference Dose has a modifying factor of 1.
  • The Oral Chronic Reference Dose has an uncertainty factor of 3000.
  • The Oral Chronic Reference Dose is based on the U.S. EPA study from 1993.
  • The Oral Chronic Reference Dose study target organ is whole body.
  • The Oral Chronic Reference Dose study critical effect is lethargy.

  • The Inhalation Chronic Reference Concentration is 3.00E+00 (mg/m3).
  • The Inhalation Chronic Reference Concentration has a modifying factor of 1.
  • The Inhalation Chronic Reference Concentration has an uncertainty factor of 300.
  • The Inhalation Chronic Reference Concentration is based on the Tyl et al. rat and mouse study from 1987.
  • The Inhalation Chronic Reference Concentration study critical effect is reduced fetal body weight, skeletal variations, and increased fetal death in mice and skeletal variations in rats.

  • The Dermal Chronic Reference Dose is 6.40E-02 (mg/kg-day).
  • The Dermal Chronic Reference Dose is based on a gastrointestinal absorption factor of 0.8000.