METHYL ISOBUTYL KETONE
Update: February 1996
Current Massachusetts Regulatory Limit
ORSGL = 0.35 mg/L.
Federal Regulatory Limit
The U.S. EPA has not published an MCL for methyl isobutyl ketone. Listed in the January 1991 Drinking Water Priority List (Fed Reg, 1991).
Basis for Criteria
The ORSGL is based on the RfD presented below and assumes that a 70 kg adult ingests 2 L/day of water. A relative source contribution factor of 20% is incorporated into the final value.
RfD: 5 x 10-2 mg/kg/day (U.S. EPA, 1988; U.S. EPA, 1991)
UF: 1000 (10 = interspecies; 10 = intraspecies; 10 = subchronic to chronic) MF: 1
The reference dose has been withdrawn from IRIS.
A NOAEL of 50 mg/kg/day was identified from a subchronic gavage study in rats (U.S. EPA, 1986). Critical effects of exposure to methyl isobutyl ketone include the liver and kidneys.
Under U.S. EPA's draft revised cancer guidelines (U.S. EPA, 1999), the data for methyl isobutyl ether are inadequate for an assessment of human carcinogenic potential. Both in vivo and in vitro genotoxicity studies of MIBK are overwhelmingly negative.
PQL: 0.01 mg/L
PQLs and analytical methods may have been updated since this guidance value was last revised. Updated analytical methods for drinking water and their associated PQLs may be found at http://www.epa.gov/safewater/methods/methods.html.
Other Regulatory Data
Any Health Advisories, Reference Doses (RfDs), cancer assessments or Cancer Potency Factors (CPFs) referenced in this document pertain to the derivation of the current guidance value. Updated information may be obtained from the following sources:
Health Advisories - The U.S. EPA provides guidance for shorter-term exposures for chemicals based on their non-cancer effects. Current health advisories may be more current than those used to derive MCLs and may be found at http://www.epa.gov/waterscience/drinking/standards/dwstandards.pdf.
RfDs, cancer assessments and CPFs - For specific information pertaining to derivation of drinking water criteria, consult the Federal Register notice that announces the availability of the most current guidance for that chemical. In addition, information on other current RfDs and CPFs as well as cancer assessments for specific chemicals may be found in the U.S. EPA Integrated Risk Information System (IRIS) at http://www.epa.gov/iris/. Please note that the information in IRIS may differ from that used in the derivation process as published in the Federal Register notice.
Federal Register. January 14, 1991. Drinking Water Priority List. (56 FR 1470).
U.S. EPA (U.S. Environmental Protection Agency). 1986. Subchronic toxicity of methyl isobutyl ketone in Sprague-Dawley rats. Office of Solid Waste. Washington, D.C..
U.S. EPA (U.S. Environmental Protection Agency). March 1988. Integrated Risk Information System (IRIS). Washington, D.C http://cfpub.epa.gov/ncea/iris/index.cfm.
U.S. EPA (U.S. Environmental Protection Agency). January 1991. HEAST (Health Effects Assessment Summary Table). Office of Research and Development. Office of Emergency and Remedial Response.
U.S. EPA (U.S. Environmental Protection Agency). July 1999. Guidelines for Carcinogen Risk Assessment. Review Draft. NCEA-F-0644. Risk Assessment Forum.