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California has approved a new, alternative “Safe Harbor” warning label for foods containing acrylamide, a naturally-occurring byproduct that occurs during high-heat cooking. Whether the new regulation moots the California Chamber of Commerce’s (“CalChamber”) ongoing legal battle against Proposition 65 (“Prop 65”) warning labels[1] remains to be seen.

What is Proposition 65?

Prop 65 provides that “[n]o person in the course of doing business shall knowingly and intentionally expose any individual to a chemical known to the state to cause cancer . . . without first giving clear and reasonable warning to such individual.” 

Prop 65 warnings have become increasingly familiar to Californians since the measure’s enactment in 1986; they can be found on food and beverages, in elevators, on household products and furniture, and even on packaging for clothing and accessories. 

What is Acrylamide?

Acrylamide is a substance that forms through a natural chemical reaction in certain plant-based foods during high-temperature cooking, and can be found in foods like potato chips, bread, grilled vegetables, nuts, crackers, and olives. There is conflicting evidence regarding the risk it poses to humans. While studies exposing laboratory rats and mice to high levels of acrylamide have been shown to produce cancer, other studies have found no consistent evidence that dietary acrylamide increases the risk of cancer in humans.[2]

CalChamber v. Becerra: California Chamber of Commerce Challenges Prop 65 Warning Labels on First Amendment Grounds

Whether businesses are required to provide a Prop 65 warning for acrylamide is currently the subject of an ongoing legal battle between CalChamber and the Attorney General of California and private enforcer Council for Education and Research on Toxics (“CERT”). In 2019, CalChamber filed suit for declaratory and injunctive relief against the Attorney General of California on First Amendment grounds, arguing that its members should not be compelled to include Prop 65 warning labels, which it alleges are false and misleading in connection with acrylamide, on their products. CERT intervened and argued that an injunction would impose an unconstitutional prior restraint on its First Amendment rights. The district court granted a preliminary injunction, finding that CalChamber was likely to succeed on the merits because neither the State nor CERT had shown that acrylamide in food poses a “purely factual and uncontroversial” cancer risk. The court also rejected CERT’s prior restraint argument, holding that the serious constitutional issues raised by CalChamber supported an injunction pending resolution on the merits.

CERT appealed the preliminary injunction and sought an emergency stay in the Ninth Circuit, which was granted by the motions panel in a 2-1 decision. The merits panel disagreed with the motions panel and unanimously affirmed the preliminary injunction, citing the “robust disagreement by reputable scientific sources,” misleading use of “known” cancer risk in light of such disagreement, and the heavy litigation burden on manufacturers to create alternative warnings.

CERT filed a Petition for Rehearing En Banc, which the Ninth Circuit denied on October 26, 2022. CERT’s motion to vacate the injunction on the grounds that the judge who issued the injunction should be disqualified due to a conflict of interest is still pending.

OEHHA’s New Regulation Language and Response to Comments

Following the district court’s decision issuing the preliminary injunction, California’s Office of Environmental Health Hazard Assessment (“OEHHA”) issued a Notice of Proposed Rulemaking, which would create a non-mandatory, alternative warning label for foods containing acrylamide. On October 26, 2022, the Office of Administrative Law approved the new regulation.

The current safe-harbor Prop 65 food warning states:

WARNING: Consuming this product can expose you to chemicals including [name of one or more chemicals], which is [are] known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to

Effective January 1, 2023, businesses will have the option to use the following non-mandatory, alternative warning:

CALIFORNIA WARNING: Consuming this product can expose you to acrylamide, a probable human carcinogen formed in some foods during cooking or processing at high temperatures. Many factors affect your cancer risk, including the frequency and amount of the chemical consumed. For more information including ways to reduce your exposure, see

In response to public comments, the OEHHA stated that the new warning label incorporates suggested elements from the district court’s opinion in CalChamber v. Becerra, namely, that acrylamide forms naturally during food preparation and is a “probable,” as opposed to a “known”, carcinogen. CERT and the Attorney General contend that the new regulation moots the case, while CalChamber argues that the new regulation is still misleading based on the conflicting evidence regarding acrylamide’s effects. It remains to be seen how the new regulation will impact the case.


[1] See Cal. Chamber of Commerce v. Becerra, 529 F. Supp. 3d 1099 (E.D. Cal. 2021); Cal. Chamber of Commerce v. Council for Educ. & Rsch. on Toxics, 29 F.4th 468 (9th Cir. 2022)