What is 4-methyl-2-pentanone (or MIBK)?

Also known as Methyl isobutyl ketone (MIBK). MIBK is an organic solvent. MIBK is among the top ten most popular organic solvents used in industry. MIBK is occasionally found as a volatile component of urine. MIBK in urine is considered as a biological marker of occupational exposure to this solvent. Olfactory perception is significant but adaptation may occur.


The major application of 4-methyl-2-pentanone is as a solvent for vinyl, epoxy, and acrylic resins, for natural resins, and for nitrocellulose. A further use is as a solvent for dyes in the printing industry. 4-Methyl-2-pentanone is also a versatile extracting agent, e.g., for the production of antibiotics, or the removal of paraffins from mineral oil for the production of lubricating oils.

Sources & Potential Exposure

Workers that use methyl isobutyl ketone may breathe in vapors or have direct skin contact. The general population may be exposed by breathing air, using consumer products such as house paint and eating foods containing methyl isobutyl ketone as a flavoring. If methyl isobutyl ketone is released to the environment, it will be broken down in air. It may be broken down by sunlight. It will move into air from moist soil and water surfaces. It is expected to move through soil.

Federal Regulations

The U.S. EPA IRIS program determined that data are inadequate for an assessment of the human carcinogenic potential of methyl isobutyl ketone based on a lack of human or animal studies at the time of the assessment

REGENESIS Treatment Products – 4-methyl-2-pentanone