The Personal Care Products Council (PCPC) filed a lawsuit in federal court in California on March 2, 2026, arguing that California’s Proposition 65 cancer warning requirement for diethanolamine (DEA) violates the First Amendment by compelling companies to convey a false and misleading message.
California’s Office of Environmental Health Hazard Assessment (OEHHA) listed DEA on Proposition 65 in 2012 as a substance known to the state to cause cancer pursuant to the state’s “Labor Code” listing mechanism. Also known as the Safe Drinking Water and Toxic Enforcement Act of 1986, Proposition 65 prohibits knowingly exposing any individual to a listed chemical without first providing a “clear and reasonable warning.” Under the Labor Code, chemicals are added to the Proposition 65 list if they are identified by the World Health Organization’s International Agency for Research on Cancer (IARC) as causing cancer in humans or laboratory animals.
IARC classified DEA as “possibly carcinogenic to humans (Group 2B)” in 2010 based largely on a single mouse study. The lawsuit points out that the strain of mice used in the study is known to be highly susceptible to the development of cancers, that a parallel rat study showed no cancer link, and that IARC identified no evidence of carcinogenicity in humans. Despite this limited scientific evidence, cosmetic and personal care product businesses “are presumptively required to provide a Proposition 65 cancer warning for their products … to consumers even though neither OEHHA nor any other governmental entity has determined that DEA is a known human carcinogen,” PCPC states in the lawsuit. Attorney General Bonta’s office has not commented publicly on the lawsuit.
Since OEHHA listed DEA as a carcinogen under Prop. 65, more than 1,400 notices have been filed alleging failures to warn for DEA in a broad range of personal care and cosmetic products, with enforcement activity for DEA rising sharply in 2024. OEHHA has proposed a safe harbor level, or no significant risk level (NSRL), for DEA of 6.4 micrograms per day for dermal exposure, although the NSRL currently remains under development.
The DEA lawsuit filed by PCPC follows other challenges to Prop. 65 cancer warning requirements for listed substances based on First Amendment grounds including lawsuits involving glyphosate, acrylamide, and titanium dioxide.
