On May 2, 2025, the U.S. District Court for the Eastern District of California permanently enjoined the state from requiring Proposition 65 warnings for dietary acrylamide, ruling that the warnings are unconstitutional. The case, California Chamber of Commerce v. Bonta (E.D. Cal. No. 2:19-cv-02019), challenged whether California could compel businesses to warn about potential dangers of dietary acrylamide without a solid scientific consensus that acrylamide poses a risk to humans.
Background on Proposition 65
The Safe Drinking Water and Toxic Enforcement Act of 1986, commonly known as Proposition 65, requires businesses to provide a "clear and reasonable" warning before "knowingly and intentionally" exposing individuals to chemicals known to cause cancer, birth defects, or other reproductive harm. Californians are well-acquainted with these warnings—typically bolded, featuring a yellow triangle with an exclamation point, and using standardized language—which appear on a wide array of products and in various environments.
The requirement to provide a warning takes effect one year after the state adds a chemical to the Proposition 65 list, and violations for failure to warn may result in penalties of up to $2,500 per day, for each violation. Warnings may be provided in several forms, including labeling consumer products, posting signs in workplaces, distributing notices in residential complexes, or publishing announcements in newspapers.
California Chamber of Commerce v. Bonta (E.D. Cal. No. 2:19-cv-02019)
In 2019, the California Chamber of Commerce ("CalChamber") filed suit challenging the requirement under Proposition 65 that businesses provide cancer warnings for products containing acrylamide—a chemical that may form naturally in cooked foods. CalChamber argued that the warnings force businesses to make misleading statements about cancer risks, despite ongoing scientific uncertainty. The group contended that requiring such labels amounts to "compelled speech."
Applying a two-part legal test, the court first examined whether the warnings were purely factual and uncontroversial, and then whether the warnings served a substantial government interest without being unduly burdensome. The warnings failed both parts of the test.
First, the court concluded that the warnings were neither factual nor uncontroversial. Public health organizations—including the U.S. Food and Drug Administration, the American Cancer Society, and the National Cancer Institute—have found the evidence linking dietary acrylamide to cancer in humans to be inconclusive or insufficient. As the court explained, regardless of how "controversial" is defined, the lack of scientific consensus confirms that the warning does not meet the standard of uncontroversial speech. Second, the court determined that the warnings did not directly advance the state's interest in protecting public health. "Misleading statements about acrylamide's carcinogenicity do not directly advance that interest," the court noted. It further stated that the state has other means to convey its message—such as public education campaigns—but it cannot "co-opt businesses to deliver its message for it."
Potential Impact Beyond Dietary Acrylamide
Although the court's ruling applies specifically to warnings about dietary acrylamide, it could have broader implications. Since Proposition 65's inception in 1987, the list of naturally occurring and synthetic chemicals (listed for cancer or reproductive harm, or both) has grown to include more than 900 substances. The risk posed by numerous chemicals on the list is similarly subject to scientific debate.
The nature of Proposition 65's enforcement scheme creates a constant threat of litigation from private enforcers through citizen suits. Businesses often face a difficult choice: Either test their products to demonstrate that chemical levels fall below the "no significant risk" threshold (i.e., no warning required)—while still risking a lawsuit—or preemptively apply a warning label, even if scientific testing suggests one may not be necessary. Some businesses opt for the latter to avoid the substantial costs of defending against enforcement actions.
U.S. District Judge Daniel Calabretta acknowledged this dilemma in rejecting California's argument that CalChamber lacked standing to bring the case. "Even if a business attempts to exempt their product by proving it contains acrylamide levels below the no significant risk level, incurring attendant costs to do so, there is no guarantee they will then be free from litigation challenging their compliance with Prop 65's warning requirements," he wrote. "Businesses must either utilize a Prop 65 warning on their products or run the risk of incurring substantial costs in defending against enforcement actions," he added, concluding CalChamber had standing to sue.
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