Proposition 65 (California)

In 1986, the state of California enacted the Safe Drinking Water and Toxic Enforcement Act, better known as "Proposition 65". Proposition 65 requires the state of California to publish a list of chemicals known to cause cancer, birth defects, or other reproductive harm. It also prohibits the purposeful release of these listed chemicals into sources of drinking water and prohibits the purposeful exposure to a listed chemical without a clear warning. Today, this list contains over 750 chemicals including additives, pesticides, household products, drugs, dyes, foods, metals, or solvents.

Proposition 65 affects many industries including food, drug, consumer product, cosmetic, and medical device manufacturers. Once a chemical is listed under Proposition 65, businesses have twelve months to comply with warning requirements through labeling, posted signs, and publications, and twenty months to comply with the prohibition of listed chemicals into sources of drinking water. Warnings are not required provided the manufacturer has conducted an exposure and risk assessment that proves that the level of exposure (including drinking water exposure, consumption exposure, residential exposure, consumer exposure and workplace exposure) is less than an amount that would pose a significant risk. Proposition 65 does not ban any products, nor is it a true assessment of potential health risks, rather it requires warnings instead. These warnings must be placed on product or food labels, posted or distributed at the workplace, a business, or in a rental-housing unit. Businesses have incurred expenses to test products, develop alternatives to listed chemicals, reduce discharges, and provide warnings, in order to comply with the law. 

Compliance is complicated in that the limits for identified chemicals can vary for compound and product. Product limits are often established based on settlements resulting from prior litigation from individual or groups challenging the warning requirements.

At Exponent we work with clients to address a variety of Proposition 65 issues including:

  • Determining if products contain Proposition 65 listed chemicals
  • Sampling of products including market basket studies for listed substances in food products
  • Conducting exposure assessments, including dietary consumption, worker, consumer, or residential exposure
  • Evaluation and development of No Significant Risk Levels (NSRLs) or Maximum Acceptable Daily Doses (MADLs )
  • Assessing exposure by comparing levels in products to NSRLs or MADLs



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