California Federal Court Finds Prop 65 Warnings for Dietary Acrylamide Violate First Amendment

On May 2, 2025, the U.S. District Court for the Eastern District of California granted a request for declaratory relief and a permanent injunction by the California Chamber of Commerce (CalChamber), finding that the state of California’s mandated warning for acrylamide in food products violates the First Amendment and enjoining enforcement of Proposition 65 (Prop 65) warning requirements as to dietary acrylamide.

Prop 65 is a California right-to-know law that requires companies doing business in California to provide a clear and reasonable warning prior to causing an exposure to a chemical known to the state of California to cause cancer, birth defects, or other reproductive harm.

Acrylamide, a substance historically used as a chemical in plastics and grouting agents, was added to the list of Prop 65 chemicals in 1990 and later identified as forming in certain foods exposed to such high-temperature cooking processes as frying, baking, and roasting. Since this discovery, studies of the carcinogenic risk of dietary acrylamide have faced varied results and extensive scientific debate.

Despite a lack of scientific support to justify a carcinogenic risk determination, hundreds of companies were sued or threatened to be sued under Prop 65 for failing to provide a “clear and reasonable” warning on food products that “[c]onsuming this product can expose you to acrylamide, which is known to the State of California to cause cancer.” Code Regs. tit. 27, § 25607.2(a)(1), (2) (Original Warning) (emphasis added).

CalChamber brought suit in 2019, alleging that requiring a Prop 65 warning for acrylamide in food is a First Amendment violation because — given the considerable scientific debate on the issue — the state does not “know” that acrylamide in food causes cancer in humans, and thus the warning language is not truthful and is likely to mislead consumers.

In 2021, the court issued a preliminary injunction due to unresolved scientific debate about the carcinogenicity of acrylamide in food. The Ninth Circuit upheld the injunction on appeal.

Six months after the court issued its preliminary injunction, the state of California issued a new safe harbor warning for acrylamide in food, to soften the “known … to cause cancer” language: “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.” Code Regs. tit. 27, § 25607.2(c)(1) (Alternative Warning) (emphasis added).

In 2023, after the Ninth Circuit issued an opinion on a First Amendment challenge to the Prop 65 warning requirement for glyphosate, the California Office of Environmental Health Hazard Assessment issued yet another change to the warning language for acrylamide, setting forth a safe harbor that required warning to include the following new caveated language:

(A) “Consuming this product can expose you to acrylamide” or “Consuming this product can expose you to acrylamide, a chemical formed in some foods during cooking or processing at high temperatures.”

(B) At least one of the following sentences:

a. “The International Agency for Research on Cancer has found that acrylamide is probably carcinogenic to humans.”

b. “The United States Environmental Protection Agency has found that acrylamide is likely to be carcinogenic to humans.”

c. “The United States National Toxicology Program has found that acrylamide is reasonably anticipated to cause cancer in humans.”

(C) The content in (A) and (B) may be followed by one or more of the following sentences:

a. “Acrylamide has been found to cause cancer in laboratory animals.”

b. “Many factors affect your cancer risk, including the frequency and amount of the chemical consumed.”

Code Regs. tit. 27, § 25607.2(c)(2) (New Warning) (emphasis added).

CalChamber moved for summary judgment, arguing the warnings are unconstitutional because they send the message that foods carrying the warning will cause cancer in humans — despite a lack of scientific consensus supporting such a conclusion. The state opposed, arguing that the warnings accurately communicated that dietary acrylamide is a likely or probable human carcinogen.

The court granted summary judgment in CalChamber’s favor, holding that applying Prop 65’s warning requirement to dietary acrylamide violated the First Amendment. The court found that Prop 65 warnings for dietary acrylamide are misleading and controversial because they state that dietary acrylamide is carcinogenic to humans despite vigorous scientific debate concerning that conclusion and compel CalChamber’s members to espouse that view despite their disagreement.

The court looked to the meaning of the warning in context (rather than the text of the warning itself), acknowledging that caveats or not, the presence of the warning nonetheless communicates the message that dietary acrylamide poses a risk of cancer. The court also found that misleading statements about acrylamide’s carcinogenicity did not advance the state’s interest in protecting the health of its citizens, nor was this the least burdensome method for the state to achieve its goals.

The court’s decision is a benefit to consumers and businesses. Prop 65 centers around informing consumers of exposure to carcinogens or reproductive toxins by requiring companies to provide a reasonable and clear warning. Litigious leveraging of Prop 65 may result in an oversaturation of warning labels – a deleterious consequence for an average consumer who will interpret these labels as affirming a definitive cancer risk despite lack of scientific support.

Acrylamide is also on the Prop 65 list of chemicals for reproductive toxicity, but that maximum allowable dose level of 140 µg/day is high relative to its “no significant risk” level for carcinogenicity (0.2 µg/day). The maximum allowable dose level for acrylamide was determined based on a study in male rats. We will monitor how the court’s carcinogenicity decision may affect acrylamide reproductive toxicity warnings. Companies should continue to consult their Prop 65 counsel for specific compliance advice.

The decision may face an appeal, and companies should continue to follow best practices to mitigate Prop 65 litigation risks, but the message is reasonable and clear: Government-mandated disclosures cannot cry wolf about carcinogens, and courts are taking note.