Prop 65

What is Proposition 65?

California’s Proposition 65 (Prop 65), also known as the Safe Drinking Water and Toxic Enforcement Act of 1986, requires the state to maintain and update a list of chemicals known to the state to cause cancer, birth defects, or other reproductive harm. The list currently includes over 950 chemicals, including both naturally occurring and synthetic chemicals that include additives or ingredients in foods, drugs, solvents, and various consumer products, such as pesticides, common household products, and dyes. These chemicals can also be used in manufacturing and construction or byproducts of chemical processes.

Prop 65 requires businesses in California to provide “clear and reasonable” warnings to anyone who may be exposed to any of these compounds by any route before knowingly and intentionally exposing individuals to these chemicals. These warnings allow individuals to make informed decisions about their exposures to these chemicals. In addition, Prop 65 prohibits California businesses from intentionally discharging significant amounts of any of the listed chemicals into sources of drinking water. 

Most importantly, Prop 65 is enforced through litigation. Once a chemical is added to Prop 65, businesses have 12 months to comply with warning requirements, which demand that the specific chemicals suspected of causing excess exposures be identified in the warning labels. The penalty for not providing warnings when necessary is $2,500 per day, per individual product and exposure.

What does a warning mean?

If a warning is placed on a product or posted or distributed at a workplace, business, or rental housing, the warning is being issued because the business is either aware or believes that it is exposing individuals to one or more chemicals listed on Prop 65. As of August 2018, by law, a warning must be provided for any listed chemicals unless the exposure to the chemical is low enough to pose no significant risk of cancer or is significantly below levels observed to cause birth defects or other reproductive harm. A business can use OEHHA’s safe harbor levels to determine if they need to provide a warning. 

What are safe harbor levels?

OEHHA has developed safe harbor levels to guide businesses in determining whether a warning is necessary or whether chemical discharges into drinking water sources are prohibited (OEHHA 2022). Safe harbor levels include No Significant Risk Levels (NSRLs) for cancer-causing chemicals and Maximum Allowable Dose Levels (MADLs) for chemicals causing reproductive toxicity. Exposure levels and discharges to drinking water sources that are below the safe harbor levels are exempt from the requirements of Prop 65 (OEHHA 2021). 

What if there is no safe harbor level?

For a majority of the chemicals listed on Prop 65, the state of California has not yet established a safe harbor level, leaving it up to businesses to determine whether a listed chemical in their product(s) or workplace would lead to excess exposures. Unless a business can show that the anticipated exposure level to a listed chemical in their product(s) or workplace will not pose a significant risk of cancer or reproductive harm, the business would be required to provide a Prop 65 warning for that chemical. 

Determining anticipated exposure levels to a listed chemical or chemicals can be complex. Businesses should consult with qualified professionals to determine whether exposure to a listed chemical in their product(s) or workplace requires a Prop 65 warning. 

How P&A Can Help

Our team of Paustenbach & Associates scientists has been helping clients address a variety of Prop 65-related issues including:

  • Compliance with new 2018 labeling requirements
  • Designing analytical testing strategies, performing exposure assessments, deriving chemical safe harbor levels (NSRLs and MADLs) for listed chemicals when none are provided by the state, and characterizing potential risks to chemicals in products or in the workplace to help guide businesses to comply with Prop 65
  • Estimating exposures using the most scientifically appropriate methods, such as developing chemical exposure models and executing exposure simulation studies
  • Providing litigation support after a product is named in a 60-day notice
  • Developing and overseeing Prop 65 compliance programs as part of a company’s quality control and quality assurance programs
  • Reviewing single products, product lines, and suppliers to manage compliance at an early stage 
  • Auditing existing programs to determine any gaps in existing quality programs
  • Issuing Safe Use Determinations (SUDs), including petitioning, advocacy, and process management with OEHHA


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