California disclosure law prompting manufacturers to shift away from toxic compounds: Study

Yahoo

12-02-2025

Manufacturers have been quietly abandoning the use of toxic ingredients in their products, in response to California's strict chemical disclosure rules, a new study has found.
By promoting increased transparency about the presence of harmful substances in consumer goods, the Golden State's right-to-know law — called Proposition 65, or 'Prop 65' — has helped shift markets toward safer items, according to the study, published on Wednesday in Environmental Science & Technology.
Under Prop 65, California maintains a list of about 900 chemicals known to cause cancer and reproductive issues. Products that contain any of these ingredients and that are sold in the state must include potential exposure warnings for consumers.
Whether the law has been effective at curbing the use of such substances — many of which are under no such microscope in other states — has thus far remained under debate.
Aiming to understand the impact, researchers from the University of California Berkeley and the Massachusetts-based Silent Spring Institute explored Prop 65's contribution to corporate behaviors.
'What we found was that companies, rather than consumers, may be most affected by the law's warning requirements,' lead author Jennifer Ohayon, a research scientist at Silent Spring Institute, said in a statement.
'By increasing businesses' awareness of chemicals in the supply chain, Prop 65 has caused them to shift away from using toxic substances, and that's a positive step for public health,' Ohayon added.
To draw these conclusions, the researchers conducted 32 interviews with business leaders at major international manufacturers and retailers — spanning more than a dozen sectors, such as home improvement, apparel, personal care, healthcare and cleaning.
Of the participants, about 78 percent cited Prop 65 as having prompted product reformulations, according to the report.
'Companies consistently told us they would rather eliminate a Prop 65 chemical altogether than post a warning,' corresponding author Meg Schwarzman, a physician and environmental health scientist at Berkeley's School of Public Health, said in a statement.
'By doing that, they avoid the threat of litigation, but they also reduce the risk to consumers and workers using the products,' Schwarzman added.
Meanwhile, around 81 percent of manufacturers said they referred to Prop 65 when purchasing raw materials or developing products, to know which chemicals to avoid.
'Companies are incredibly reluctant to put a label on a product that says it contains a chemical that causes cancer,' Ohayon said. 'That was the biggest driving force behind their decisions to reformulate.'
Although manufacturers could technically circumvent the law by retooling their products to include Prop 65-listed ingredients at just below their designated safe harbor levels, the researchers found that most companies chose to distance themselves from those substances entirely.
The authors noted, however, that when Prop 65 has prompted companies to reformulate their products, they tend to do so without evaluating the safety of the alternative compounds — aside from typically avoiding the use of other substances on the list.
And that force has had far-reaching impacts not just in California, but also in the rest of the United States — even in the absence of comparable state-level laws akin to Prop 65.
Some 63 percent of manufacturers credited Prop 65 for propelling the reformulation of their products sold outside the Golden State, according to the study.
This finding is in keeping with previous research conducted by the Silent Spring and Berkeley team, which previously determined that blood levels of certain compounds decreased nationwide in the years following Prop 65 listings.
'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,' Ohayon said.
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