Prop 65 gives toxic ingredients the boot

A new study by the Silent Spring Institute and University of California, Berkeley shows how laws that promote greater transparency around harmful chemicals in products can shift markets toward safer products.

The analysis, published in the journal Environmental Science & Technology, focused on California’s right-to-know law called Proposition 65, or Prop 65. Under the law, the state of California maintains a list of approximately 900 chemicals known to cause cancer, birth defects, or reproductive harm. Companies that sell products in California are required to warn consumers if their products expose them to harmful amounts of the chemicals.

Until recently, there had been little research on the effectiveness of Prop 65, with some critics contending the law creates too many warnings with little impact on individual behaviors, while others argue the law is less effective than those that restrict or ban chemicals outright.

“We wanted to go deeper and understand to what extent the law has created more systems-level change,” says lead author Dr. Jennifer Ohayon, a research scientist at the Silent Spring Institute. “What we found was that by increasing awareness of chemicals in the supply chain, Prop 65 has caused businesses to shift away from using toxic substances and that’s a positive step for public health.”

To assess the impact of Prop 65, Ohayon and her research partners conducted 32 semi-structured interviews with business leaders at major manufacturers and retailers. The businesses spanned more than a dozen sectors including home improvement, clothing, personal care, cleaning, and healthcare, among others. Some key takeaways from the interviews include:

• 78% of the interviewees said Prop 65 has prompted them to reformulate their products
• 81% of manufacturers interviewed said they look to Prop 65 to know which chemicals to avoid when formulating their products or purchasing raw materials from suppliers
• 63% of manufacturers said that Prop 65 also drives the reformulation of their products sold outside of California

“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,” says Ohayon.

The researchers also saw impacts on the supply chain through third party “green” certification programs that have incorporated Prop 65 chemicals into their safety criteria. For instance, several major healthcare institutions said they encouraged their suppliers to use certifiers such as Green Seal, which prohibits Prop 65 chemicals in the cleaning products it certifies.

Under the law, companies can avoid triggering a warning requirement by reformulating their products so that any Prop 65 chemicals present are below a “safe harbor” level.

“What’s interesting is that companies consistently told us they would rather eliminate a Prop 65 chemical altogether than post a warning,” says co-author Dr. Meg Schwarzman, a physician and environmental health scientist at the UC Berkeley School of Public Health. “By doing that, they avoid the threat of litigation, but they also reduce the risk to consumers and workers using the products.”

The study is the first to use in-depth interviews with representatives from diverse industry sectors to understand the influence of Prop 65 on internal corporate decision-making.

The work is also part of a larger research effort to collect metrics on the effectiveness of Prop 65 at reducing people’s exposures to toxic chemicals. In a study published last fall, the Silent Spring and UC Berkeley team found levels of certain chemicals in people’s bodies went down both in California and nationwide in the years following the chemicals’ listing.

Ohayon explains this is consistent with the findings from her interviews. When companies reformulate their products to comply with Prop 65, they tend to apply those changes across all of their products, not just ones sold in California.

“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,” says Ohayon.