California’s Proposition 65: Impact Beyond Consumer Awareness

A recent study published on February 12, 2025, in Environmental Science & Technology, highlights the extended implications of California’s right-to-know law, known as Proposition 65. The research suggests that this legislation influences not only consumer behavior but also industry practices regarding the use of toxic chemicals in manufacturing processes.

Understanding Proposition 65

Proposition 65, enacted in 1986, mandates that companies in California disclose and label products containing chemicals identified as mutagenic, carcinogenic, or harmful to reproductive health. The comprehensive list of substances regulated under this law, managed by the Office of Environmental Health Hazard Assessment (OEHHA), currently encompasses approximately 900 chemicals. While prior studies have focused on how Proposition 65 affects consumer choices, there has been limited understanding of its impact on corporate decision-making.

Research Overview

The study, led by Jennifer Ohayon and her team from the Silent Springs Institute in Massachusetts, involved 32 interviews with representatives from various sectors, including cleaning products, personal care, health care, electronics, pesticides, apparel, home improvement, chemicals, automotive, flooring, fragrances, and education. These interviews aimed to gauge how Proposition 65 influences product formulation and supply chain practices within these industries.

Findings from Industry Interviews

Significantly, the findings indicated that 78% of the interviewees reported reformulating their products as a direct response to Proposition 65. Interestingly, rather than merely ensuring compliance by adhering to the safe harbor levels established by the law, 41% of the participants opted to completely eliminate the listed toxic chemicals from their products. This decision often stemmed from ambiguities in Proposition 65 regarding how safe harbor levels translate into actual chemical concentrations in products, which heightens the risk of civil litigation for non-compliance.

The researchers concluded that the implications of Proposition 65 extend beyond consumer protection, potentially leading to broader public health benefits as companies proactively eliminate hazardous substances from their product lines.

Regulatory Updates and Industry Response

The list of chemicals regulated under Proposition 65 is regularly updated based on emerging health research. For instance, as of January 3, 2025, OEHHA added a reproductive toxicity endpoint for bisphenol S (BPS), which was previously recognized as a reproductive toxicant in females. The new classification acknowledges its harmful effects on males as well. Companies are granted a one-year grace period to implement warning labels for BPS exposure in California. However, many interviewees in Ohayon’s study expressed that they often preemptively adjust their formulations in anticipation of such regulatory updates to mitigate potential compliance issues.

Enhancing Supply Chain Transparency

Interview participants also shared insights on how they utilize Proposition 65 as a tool to enhance transparency within their supply chains. Notably, 81% of respondents indicated that they refer to Proposition 65 as an authoritative list of hazardous chemicals to avoid when sourcing from suppliers. Additionally, 69% stated they leverage Proposition 65 to request detailed ingredient information from their suppliers. Several interviewees noted instances where they terminated relationships with suppliers who failed to adapt their formulations in alignment with the demands of Proposition 65.

This feedback illustrates that practices within larger companies can have significant ripple effects across entire industries, compelling suppliers to reformulate products and adopt safer practices in response to the growing demand for compliance with Proposition 65.

Concluding Insights

The study put forth by Ohayon and her colleagues illuminates the multifaceted impact of Proposition 65 beyond consumer awareness. By mandating transparency regarding the presence of toxic chemicals, the law has prompted substantial shifts in industry practices, encouraging companies to prioritize public health and safety. As Proposition 65 continues to evolve with ongoing regulatory updates and industry responses, it remains a pivotal framework for fostering safer products and enhancing supply chain accountability in California and beyond.

References

Ohayon, J.L., et al. (2025). “How a Right-to-Know Law Shifts Industry away from Chemicals of Concern: The Case of California’s Proposition 65.” Environmental Science & Technology. DOI: https://doi.org/10.1021/acs.est.4c07495

California Office of Administrative Law (January 3, 2025). “California Regulatory Notice Register.”

Amudalat Ajasa (February 12, 2025) “California’s chemical warning labels are everywhere. A study finds they’re working.” The Washington Post.