Recent peer-reviewed research revealed that California’s Proposition 65 (Prop 65), which regulates toxic chemicals such as PFAS and phthalates commonly found in plastic lunch boxes, food packaging, backpacks and storage cases, has effectively reduced the levels of harmful substances in residents’ bodies.

California’s Prop 65, enacted in 1986, requires companies selling products within the state to disclose the presence of chemicals known to cause cancer, birth defects or reproductive harm. The regulation currently encompasses approximately 850 chemicals, including six phthalates identified as potentially risky to health.

Gretchen Salter, strategic advisor at Safer States, tells Packaging Insights: “This study provides proof that state restrictions on toxic chemicals have real-world impacts. Reducing the use of toxic chemicals leads to lowered levels of toxic chemicals in people. It is important to note that California also adopted policies in addition to Prop 65 that phased out the use of toxic chemicals, such as banning PFAS in food packaging.”

“Laws that states adopt send powerful market signals that ripple beyond a particular state. When a state adopts a restriction, manufacturers often revise their entire supply chain, ultimately benefiting other states.”

The impact of law

The paper, published on Environmental Health Perspectives, compared data for 37 Prop 65 chemicals and related compounds. These are substances that federal regulators also monitor in the bodies of people across the US.

The study highlighted a 77% reduction in two PFAS compounds levels, namely perfluorooctane sulfonate (PFOS) and 2-N-Methylperfluorooctanesulfonamidoacetic acid (N-MeFOSAA) and a 62% dro in Perfluorooctanoic acid (PFOA) levels among Californians, which are lower than US national medians.

Bisphenol-A (BPA), commonly used in plastic products, saw a 15% decrease in median concentrations after its inclusion on the Prop 65 list.

Claudia Polsky, a clinical professor of law and the founding director of the Environmental Law Clinic at the University of California, Berkeley, US, and a co-author of this research, shares with us: “Prop 65 is only one of the regulatory, and possibly also, cultural and demographic factors driving the differential between Californians’ and other Americans’ exposure levels. The volume of Prop 65 litigation over failure to warn, and Prop 65’s role in spurring certain direct regulations of toxic chemicals in California may be partly causal.”

“Our observations are preliminary, and more research expressly focused on the exposure differential would be useful.”

Challenges in chemical regulation

Polsky notes that litigation settlements in Prop 65 cases sometimes specify which material substitutions are permissible if a product is proposed to be reformulated. 

“Policymakers are also beginning to respond to the issue of problematic substitution. The prime example is California’s Safer Consumer Product program, created by statute decades after Prop 65. It requires manufacturers of targeted toxics-containing products to do an alternatives assessment to demonstrate that the replacement chemistries they contemplate won’t pose the same toxic risk. ”

Gaps also exist in current biomonitoring practices, particularly in detecting newer or less-studied chemicals found in plastics and packaging.

“At the federal level, the Centers for Disease Control and Prevention typically biomonitors only those chemicals already known to be both toxic and abundant in commerce,” says Polsky.

“This approach does not contemplate a robust screening function with respect to emerging chemicals or data-poor chemicals. Biomonitoring for newer or less studied chemicals in plastics and packaging can be a potentially important surveillance role for state biomonitoring programs, although those only exist in a few states.”

States leading the charge

While California demonstrates the long-term benefits of regulatory frameworks, other states in the US are taking proactive steps to eliminate PFAS at the source. 

Last year, Minnesota Governor Tim Walz signed legislation widely regarded as one of the US’s most comprehensive bans on PFAS. The law prohibits PFAS in 13 categories of consumer products, including clothing, cookware, children’s items and food packaging. 

Starting January 1, 2025, the first phase of the ban will take effect in Minnesota, targeting products with intentionally added PFAS. Empty packaging containing PFAS will face a later deadline of 2032 unless deemed a “currently unavoidable use.”

The new law requires manufacturers to start submitting detailed reports to the Minnesota Pollution Control Agency on products containing PFAS beginning in 2026. It also bans the sale of all products containing PFAS by 2032.

“States should continue to lead on toxics reductions through policies that would require companies to tell us what they are using in their products, eliminate the most hazardous chemical classes from products, and create incentives for safer solutions,” Salter comments.

“We also need policies that transform the way chemicals enter the market in the first place. Makers of chemicals should have to demonstrate that they are safe before they are marketed. Finally, all levels of government need to hold polluters accountable for the harm they have caused to communities.”