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OEHHA Data Call-In for Diaminotoluenes Reveals Increased Scrutiny of Proposition 65 Listings

On November 7, 2014, the California Office of Environmental Health Hazard Assessment published a Request for Relevant Information for diaminotoluene (mixed). This data call-in represents the first step of OEHHA’s reconsideration of the Proposition 65 carcinogen listing of this particular category of chemicals, which covers all isomers of diaminotoluene. This regulatory proceeding reveals more than initially meets the eye.

Diaminotoluenes are used in the preparation of dyes and are intermediates in the synthesis of other chemicals. There are a number of diaminotoluene isomers, including 2,4-diaminotoluene.  The original 1990 listing of diaminotoluene (mixed) — i.e., all diaminotoluene isomers –was based on U.S. Environmental Protection Agency’s 1988 hazard evaluation of the substance under its Comprehensive Environmental Response, Compensation and Liability Act authority. Although USEPA’s conclusion encompassed all isomers of diaminotoluene, USEPA stated that its conclusion was based only on the carcinogenic properties of the 2,4-diaminotoluene isomer. The question, then, is whether the scientific evidence meets Proposition 65’s standard that “diaminotoluene (mixed),” as opposed to only 2,4-diaminotoluene, is known to the State of California to cause cancer.

On October 21, 2014, Big Lot Stores, Inc. submitted to OEHHA a request for reconsideration of the Proposition 65 listing. In response, OEHHA now seeks to clarify the scope of the listing — i.e., does the listing properly encompass all isomers of diaminotoluene, or only 2,4-diaminotoluene — by referring the question to its Carcinogen Identification Committee. The November 7, 2014 Request for Relevant Information, which seeks information about the carcinogenic properties of the other isomers, is the first step of the CIC review process. The ultimate outcome may be a narrowing or even elimination of the scope of this chemical listing.

Scientifically well-founded chemical listings are not only required under the law, but are critical to impose some measure of discipline on an otherwise undisciplined world of Proposition 65 enforcement. Big Lots Stores’ request for reconsideration reveals the regulated community’s increasing concern about inappropriate and overbroad Proposition 65 listings, which lead to unnecessary enforcement actions.  It also reveals the regulated community’s willingness to challenge those decisions and ensure that OEHHA adheres to the Proposition 65 legal standard for chemical listing.


Ms. Grimaldi maintains a diverse environmental law practice focusing on chemical and product regulation and litigation defense. Her practice areas include Proposition 65, California's Safer Consumer Products Regulations, California's Rigid Plastic Packaging Container Act and the federal Toxic Substances Control Act. Ms. Grimaldi graduated from the University of California Hastings College of the Law magna cum laude and holds a Bachelor of Science Degree in Bacteriology from University of California, Davis. Prior to attending law school, she worked as a research assistant in laboratories at the University of California, San Francisco Cancer Research Institute and at the University of California, San Francisco School of Medicine.