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Methyl isobutyl ketone (MIBK) Quickview (CASRN 108-10-1)

Health assessment information on a chemical substance is included in IRIS only after a comprehensive review of toxicity data by U.S. EPA health scientists from several Program Offices, Regional Offices, and the Office of Research and Development.

Disclaimer: This QuickView represents a snapshot of key information. We suggest that you read the IRIS Summary to put this information into complete context.

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Status of Data for Methyl isobutyl ketone (MIBK)

File First On-Line: 03/31/1987; Last Significant Revision: 04/25/2003

Category (section)
Last Revised
Oral RfD Assessment Withdrawn; discussion 04/25/2003
Inhalation RfC Assessment Yes 04/25/2003
Carcinogenicity Assessment Yes 04/25/2003
  • Hexon
  • Hexone
  • Isobutyl methyl ketone
  • Isopropylacetone
  • Ketone, isobutyl methyl
  • Methylisobutylketon
  • Methyl isobutyl ketone
  • 4-Methyl-pentan-2-on
  • 2-Methyl-4-pentanone
  • 4-Methyl-2-pentanone
  • 4-Metilpentan-2-one
  • more...
Methyl isobutyl ketone (MIBK) Source Documents
Revision History
Date Section Description
I., II., VI. RfD, RfC and cancer sections updated
Chronic Health Hazard Assessments for Noncarcinogenic Effects

Reference Dose for Chronic Oral Exposure (RfD)

Information reviewed but value not estimated. See IRIS Summary.

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Reference Concentration for Chronic Inhalation Exposure (RfC)

Critical Effect
Point of Departure*
Reduced fetal body weight, skeletal variations, and increased fetal death in mice, and skeletal variations in rats. NOAEL (HEC): 1026 mg/m3 300 3 mg/m3

* The Point of Departure listed serves as a basis from which the Inhalation RfC was derived. See Discussion of Conversion Factors and Assumptions for more details.

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Carcinogenicity Assessment for Lifetime Exposure
  • Weight-of-Evidence Characterization
    • Data are inadequate for an assessment of human carcinogenic potential
  • Weight-of-Evidence Narrative:
    • Under the draft revised cancer guidelines (U.S. EPA, 1999), the data for MIBK are inadequate for an assessment of human carcinogenic potential. No data were located regarding the existence of an association between cancer and MIBK exposure in humans, but studies of the in vivo and in vitro genotoxicity of MIBK overwhelmingly provided negative responses.
    • This may be a synopsis of the full weight-of-evidence narrative. See IRIS Summary.

Quantitative Estimate of Carcinogenic Risk from Oral Exposure

  • Not Assessed under the IRIS Program.

Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure

  • Not Assessed under the IRIS Program.

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