The Impact of Proposition 65 on Chemical Exposures Relevant

Institution: University of California, Berkeley
Investigator(s): Megan Schwarzman, MD, MPH -
Award Cycle: 2017 (Cycle 23) Grant #: 23QB-1881 Award: $808,284
Award Type: SRI Request for Qualifications-RFQ
Research Priorities
Etiology and Prevention>Etiology: the role of environment and lifestyle



Initial Award Abstract (2017)

The research team for this project includes:

Non-technical overview of the research topic and relevance to breast cancer: California’s Safe Drinking Water and Toxic Enforcement Act of 1986 (commonly known as Proposition 65) requires the state of California to publish a list of chemicals that cause cancer, birth defects, or reproductive harm. The law also requires businesses to notify California consumers, residents, and in some cases workers if products contain significant amounts of one or more of the chemicals that appear on the Proposition 65 list. Warnings are also required if the chemicals are found in people’s homes, or if they are released into the environment in significant amounts. The Proposition 65 chemical list now includes over 800 chemicals. However, in the 30 years since its enactment, no study has measured what effect the law has had on Californians’ exposure to chemicals on the list. We will assess the law’s impact by evaluating its influence on business practices, public knowledge, and chemical exposures, focusing specifically on chemicals that may increase breast cancer risk. We hope to determine whether the law has resulted in lower exposures to these chemicals and to identify further actions policymakers can take to protect public health under the law.

Research question(s) or central hypotheses: We will address the following questions: 1) Have levels of breast cancer-related chemicals in Californians’ bodies changed since the chemicals were included in Proposition 65?; 2) Has the amount of these chemicals released into California’s air and water changed?; 3) How have consumers and workers responded to Proposition 65 warnings?; 4) How have businesses changed their products or manufacturing practices in response to Proposition 65?; and 5) How have lawsuits under Proposition 65 changed the chemicals used in consumer products?

General methodology: We will: 1) Analyze data from biomonitoring—the measurement of toxic substances in people’s bodies through urine or blood samples—to understand changes in Californian’s exposure to breast cancer-related chemicals listed under Proposition 65; 2) Conduct focus groups with a diverse subset of California residents and workers to understand how people respond to Proposition 65 warnings; 3) Evaluate businesses’ response Proposition 65 chemical listings by conducting interviews, product testing, and tracking environmental releases; 4) Conduct a legal analysis of Proposition 65, including collecting information on lawsuit outcomes and interviewing attorneys; and 5) Analyze aspects of the law that could be improved to reduce public exposures to chemicals linked to breast cancer.

Innovative elements: Although the goal of chemical regulation is generally to improve public health, rarely has research been conducted to understand whether regulations have their intended effect. We will use multiple approaches to investigate the influence of Proposition 65, including direct measurements of chemicals in people, product testing, interviewing people about their responses to Proposition 65 warnings, and a close look at changes in business practices. Furthermore, we will study whether the law has equally impacted California’s diverse residents, for example, by comparing chemical levels in Californians with different racial, ethnic, and income backgrounds. By focusing on breast cancer-related chemicals, we hope to understand the law’s effect on public health. While the majority of breast cancer research focuses on treatment, this project aims to contribute to prevention by investigating how to reduce exposure to chemicals linked to breast cancer.

Advocacy involvement and relevance to the human issues associated with breast cancer: We expect to identify additional actions decision-makers can take to increase the effectiveness of Proposition 65 in reducing exposure to chemicals linked to breast cancer. We will partner with several California advocacy organizations for input in selecting chemicals to analyze, for instance, and in recruiting participants for focus group that reflect the state’s economic, racial, and ethnic diversity. Our advocacy partners will help translate our research findings for decision-makers and the media and will distribute the findings via their networks. Input from our partners will ensure that the research reflects priorities of the diverse communities served by these organizations, including workers in industries that are at a higher risk for breast cancer.




Progress Report 1 (2018)

California’s Safe Drinking Water and Toxic Enforcement Act of 1986 (commonly known as Proposition 65) requires the state to identify chemicals that cause cancer or reproductive harm. It prohibits discharge of those chemicals to drinking water and requires consumer and worker warnings when people will be exposed to listed chemicals above specified risk level. Our research investigates whether and how Proposition 65 has reduced population-level exposures to chemicals linked to breast cancer. We seek to identify particularly effective elements of the law, as well as aspects that can be improved to better protect public health.

In this first year of a 3-year project we have made significant progress on our research aims.

Aim 1 - Assess population-level shifts in exposures to Proposition 65 chemicals associated with breast cancer. Accomplishments: We created a list of breast cancer-relevant chemicals and endocrine disrupting compounds (EDCs), cross-referencing these chemicals with chemicals that appear on the Proposition 65 list and looking at biomonitoring data from before and after the date they were listed. Findings: For many chemicals (e.g., phthalates), levels in people decreased following Proposition 65 listing. Next steps: We will extend our analysis to more chemicals, enumerate the confounding effects of other regulatory and market pressures, and investigate regional differences.

Aim 2 - Investigate whether and how consumer and worker perceptions and behaviors have changed as a result of Proposition 65 warnings and public education campaigns. Scheduled for Year 2.

Aim 3 - Assess changes in business practices associated with chemical listing under Proposition 65. Accomplishments: We are interviewing 40-50 businesses to understand how they interact with Proposition 65, and to solicit their input on possible improvements to Proposition 65. We are analyzing chemical and product emissions data to track changes in chemical production and use. Next Steps: We will transcribe and analyze business interviews, as well as analyzing trends in environmental releases of Prop 65 chemicals relevant to breast cancer.

Aim 4 - Analyze legal and policy principles that underlie Proposition 65 and its enhancements, describing the mechanisms of Proposition 65’s impact, and assessing trends in chemicals targeted by enforcement. Accomplishments: We have investigated Prop 65 enforcement activity for a pilot group of breast cancer-relevant chemicals. We have also conducted a literature review, interviews, and web searches for relevant legal activity. Findings: We have generated hypotheses about the characteristics of substances, commercial applications, and regulatory contexts that either enable Proposition 65 enforcement or limit its viability. Additionally, we have identified a range of ways that Proposition 65 is employed (and its impact amplified by) state regulations, third party certifications, hazard screening tools, advocacy campaigns, and voluntary industry compliance. Next steps: Continue researching the history and outcomes of Proposition 65 legal actions, as well as investigating the indirect mechanisms of its impact. Based on these findings, we will conduct semi-structured interviews with Proposition 65 litigators to further expose factors that influence the law’s implementation.