Entering the US market? Get to grips with California’s Prop 65

What does Prop 65 involve?

Prop 65 requires businesses to provide a ‘clear and reasonable’ warning when products may expose individuals in California to concentrations of chemicals identified by the state as causing cancer or being associated with reproductive or developmental toxicity.

Importantly, the practical reach of Prop 65 can extend beyond California. Products exported to other parts of the US may ultimately be distributed in the state or purchased online by California-based consumers.

Prop 65 operates as a liability-based framework, rather than an approval regime. There is no formal compliance pathway to follow. Instead, businesses must determine whether use of their product by typical users could result in exposure to listed chemicals at concentrations that exceeds Safe Harbor Levels published by California’s Office of Health Hazard Assessment (OEHHA).

Responsibility sits with the business that places a product on the market. They must evaluate products independently, interpreting scientific data and considering typical use scenarios, and then make their own risk management decision on whether a warning is warranted.

What are Safe Harbor Levels?

OEHHA uses Safe Harbor Levels as a toxicology benchmarks against which the risk of exposure to listed chemicals can be assessed. Where exposure to typical users is determined to be below these levels, a Prop 65 warning is not required. For cancer-causing chemicals, the Safe Harbor Levels are referred to as No Significant Risk Levels (NSRLs). For listed chemicals known to the state of California to be associated with reproductive or developmental toxicity, the Safe Harbor Levels are known as Maximum Allowable Dose Levels (MADLs).

Safe Harbor Levels have not been established for every substance on the Prop 65 list. Only around a third of listed chemicals currently have a defined threshold, and the list itself continues to grow over time.

In the absence of an official Safe Harbor Level, it is possible to derive a NSRL or MADL using OEHHA’s published methodology and technological guidance. This involves reviewing publicly available toxicology literature and existing risk assessments and applying risk assessment methodologies deemed appropriate by OEHHA.

When is a Prop 65 warning needed?

A Prop 65 warning is required when a product sold in California could expose ‘average consumers’ to listed substances at concentrations that exceed Safe Harbor Levels. Warnings are also required if a business cannot demonstrate that exposure to a typical user to a listed chemical remains below the Safe Harbor Level.

To determine whether a warning is needed, the first step is to conduct a technical evaluation of the product. This involves auditing supplier information related to ingredients, raw materials, and packaging composition to identify whether any Prop 65 listed substances are present. Reviewing publicly available enforcement data – such as the California Attorney General’s 60-Day Notice database – for similar product categories can also provide useful insights.

If no listed substances are identified, it’s likely that a warning is not necessary. Where one or more listed substances are present, the decision-making process becomes more nuanced. Some companies decide whether to provide a warning based solely on the presence or absence of listed chemicals. Others proceed based on the outcomes of more detailed exposure assessments. Each approach carries different commercial and enforcement implications, making evidence-based decision making essential. Companies wishing to lower their litigation risk, particularly in complex situations are recommended to consult with an attorney with Prop 65 experience.