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California Proposes Listing Methyl Isobutyl Ketone Under Prop. 65

The California Environmental Protection Agency's (Cal/EPA) Office of Environmental Health Hazard Assessment (OEHHA) issued a notice on September 6, 2013, stating that it intends to list methyl isobutyl ketone (MIBK) as known to the State to cause reproductive toxicity under Proposition 65. Proposition 65, also known as the Safe Drinking Water and Toxic Enforcement Act of 1986, requires the governor of California to publish, at least annually, a list of chemicals "known to the State to cause cancer or reproductive toxicity." Products containing listed substances are subject to disclosure requirements under the law.


OEHHA is proposing to list MIBK under Proposition 65's authoritative bodies listing mechanism based on a finding by the U.S. Environmental Protection Agency (EPA). In particular, OEHHA cites EPA's 2003 online Integrated Risk Information System (IRIS) entry for MIBK, a review and summary of the available toxicological data supporting the IRIS entry, and the studies cited in these documents, as a basis for the listing.


(For more information on the authoritative bodies mechanism, see the article, OEHHA to Identify Chemicals Being Considered for California's Prop. 65 List Under Authoritative Bodies Mechanism.)