How California’s Prop. 65 changed how (some) products are made

Have you ever seen a label accompanying a product that says it contains chemicals “known to the State of California” that could cause harm? That’s thanks to a law nicknamed Proposition 65, which gives Californians the right to know whether they might be exposed to certain chemicals. Researchers publishing in ACS’ Environmental Science & Technology show that Proposition 65 has influenced manufacturers, too, by encouraging them to reformulate their products.

In 1986, a ballot measure titled California’s Safe Drinking Water and Toxic Enforcement Act went into effect. Better known to the public as Proposition 65, this right-to-know law requires companies to warn consumers if their products might expose people to chemicals that may cause cancer or developmental or reproductive harm. The law requires the state to maintain a list of such chemicals, which has grown to include more than 900 entries. But beyond requiring companies to issue warnings meant to inform, and potentially influence, consumers, has Proposition 65 changed industry behaviors as well? Jennifer Ohayon and colleagues set out to answer this question.

The researchers interviewed 37 people from some of the largest companies across industries affected by the law, including manufacturers, retailers, consultants and trade association representatives. The interviews revealed that many companies reformulated products to remove any chemical covered by Proposition 65 to avoid warnings and potential lost sales. Because these reformulated products are sold nationwide, companies also avoided having to make California-specific products. In addition, the team found that the law prompted many companies to dig deeper into their supply chains and discover exactly which chemicals were going into their products to avoid potential lawsuits over nondisclosed chemicals.

However, Proposition 65 still has room for improvement. The list of chemicals covered by the law isn’t exhaustive — notably, many per- and polyfluoroalkyl substances (PFAS) are not included — and it takes time to add new ones. As a result, in some cases manufacturers have reformulated a product to remove the Proposition 65 chemicals only to replace them with an unlisted chemical that might also be harmful but doesn’t require a warning.

In all, the researchers say this study helps provide a behind-the-scenes look at some of the downstream effects of Proposition 65 on several industries. “Our study shows that by increasing businesses’ awareness of harmful chemicals in the supply chain, Proposition 65 has caused them to shift away from using toxic substances, and that’s a positive step for public health,” concludes Ohayon.

The authors acknowledge funding from the California Breast Cancer Research Program.

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