A new study by Silent Spring Institute and the University of California, Berkeley has revealed that laws requiring companies to disclose harmful chemicals in their products can lead to significant changes in the marketplace.
The research, published in Environmental Science & Technology, focuses on California’s Proposition 65 (Prop 65), a law designed to inform the public about chemicals linked to cancer, birth defects, or reproductive harm.
The study found that Prop 65 is influencing businesses more than consumers, encouraging manufacturers to remove toxic chemicals from their products.
How Prop 65 Works
California’s Prop 65 law requires the state to maintain a list of approximately 900 harmful chemicals. If a product sold in California contains any of these chemicals above a certain level, companies must provide a clear warning label. While the law does not ban chemicals outright, it gives consumers the right to know about potential health risks.
For years, some critics argued that Prop 65 leads to too many warnings and does little to change consumer behavior. Others have questioned its effectiveness compared to stricter chemical bans. However, this new study suggests that the biggest impact of Prop 65 happens behind the scenes—within the companies themselves.
Companies Are Reformulating Their Products
To understand how Prop 65 influences businesses, lead researcher Dr. Jennifer Ohayon conducted in-depth interviews with representatives from major manufacturers and retailers across industries such as home improvement, personal care, clothing, and healthcare.
Key findings from the interviews include:
- 78% of companies reported that Prop 65 led them to reformulate their products to remove harmful chemicals.
- 81% of manufacturers said they use the Prop 65 list to decide which chemicals to avoid when developing new products or sourcing raw materials.
- 63% of manufacturers reported reformulating not only for California but also for products sold in other markets.
Many companies admitted they would rather remove a toxic chemical altogether than place a cancer or reproductive harm warning on their products. This pressure to avoid warning labels has been a strong motivator for businesses to seek safer alternatives.
“Companies are incredibly reluctant to put a label on a product that says it contains a chemical that causes cancer, and that was the biggest driving force behind their decisions to reformulate,” said Ohayon.
Impact Beyond Individual Products
The study also found that Prop 65 influences the supply chain in broader ways. Many businesses rely on third-party safety certifications, such as Green Seal, which prohibits Prop 65 chemicals in cleaning products.
In response, some healthcare institutions now require their suppliers to meet these stricter certification standards, further reducing the presence of harmful chemicals in everyday products.
According to Dr. Meg Schwarzman, a co-author of the study and environmental health expert at UC Berkeley, companies would rather remove a harmful chemical entirely than risk lawsuits or damage to their brand. “By doing that, they avoid the threat of litigation, but they also reduce the risk to consumers and workers using the products,” she explained.
Evidence That Prop 65 Is Reducing Chemical Exposure
The research is part of a broader effort to measure Prop 65’s impact on public health. In a 2024 study, the same research team found that levels of certain toxic chemicals in people’s bodies decreased both in California and nationwide after those chemicals were added to the Prop 65 list.
This suggests that once companies reformulate their products to comply with Prop 65, they often extend those changes to all markets, not just California.
The Role of State Laws in Chemical Safety
The study highlights how state laws can drive nationwide changes in chemical safety, especially in the absence of federal regulations. Because California is a major market, companies often find it easier to update all their products rather than create separate versions just for one state.
“In the absence of federal regulations, these findings underscore the important role that states, especially large ones like California, can play in protecting the broader public from chemicals that could harm their health,” said Ohayon.
Conclusion
Prop 65 may not directly restrict chemicals, but it has been remarkably effective in encouraging businesses to make their products safer. Rather than just informing consumers, the law has pushed companies to change their manufacturing processes, leading to fewer harmful chemicals in products across the country.
This study reinforces the idea that transparency laws can drive industry-wide change, benefiting public health on a large scale.
The research findings can be found in Environmental Science & Technology.
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