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Regulation overview

California Proposition 65: Warnings About Listed Chemicals

California's Proposition 65 (the Safe Drinking Water and Toxic Enforcement Act of 1986) requires businesses to provide a clear and reasonable warning before knowingly and intentionally exposing anyone in California to a chemical on the state's list of chemicals known to cause cancer, birth defects or other reproductive harm. A Prop 65 warning does not mean a product is banned or unsafe by itself.

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Who it applies to

Proposition 65 applies to businesses with ten or more employees that sell products in California, operate there or discharge into California sources of drinking water. Small businesses with fewer employees are exempt from the warning requirement. Government agencies are also exempt. Many manufacturers outside California are affected because they sell to California consumers or through retailers there. The list is maintained by California's Office of Environmental Health Hazard Assessment (OEHHA), and the list is updated periodically.

What it requires

  • Warnings. A business must give a clear and reasonable warning before exposing people to a listed chemical, unless the exposure is below levels defined in regulations (safe harbor levels) or an exemption applies. Regulations set the content and delivery methods of warnings, including for consumer products, workplaces, and environmental exposures. Warnings on products typically use a yellow triangle with an exclamation mark and name at least one listed chemical.
  • Discharge prohibition. Businesses may not knowingly discharge listed chemicals into sources of drinking water.
  • Enforcement. The Attorney General, district attorneys, certain city attorneys and private parties acting in the public interest can bring actions, after giving notice. This private enforcement is a major driver of compliance.

The list contains many chemicals, including industrial chemicals, pesticides, metals, drugs and natural substances. Specific exposure thresholds and warning wording are in the regulations and change over time, so use OEHHA's resources for decisions.

How Prop 65 shows up on SDSs

Prop 65 is not part of OSHA's HazCom, and SDS content on it is voluntary. Many US sheets include a statement in Section 15 naming listed ingredients and the harm (cancer, reproductive toxicity, or both), or stating that none are present. Workplace warnings under Prop 65 can be given through other means, such as an employee communication. Sheets sometimes cross-reference to the toxicology data in Section 11. Absence of a statement on the sheet does not mean the product has no listed chemicals.

Key differences versus OSHA HazCom

  • State law. Prop 65 is California law, not federal.
  • List-based. It is based on a list of chemicals and exposure thresholds, not hazard classes.
  • Audience. It protects the general public as well as workers.
  • Enforcement. Private enforcement is allowed, unlike HazCom.
  • Not a classification. A Prop 65 listing is based on different authoritative sources than GHS hazard classification, and the two systems can disagree.

Practical points

  • Check your product ingredients against the current list, including trace contaminants where relevant.
  • Evaluate whether exposure is above safe harbor levels, or get expert advice.
  • Coordinate the warning on your label with the supplier's statements in the SDS. See labeling requirements.
  • For federal reporting regimes, see EPCRA and TSCA.

Worked scenario: a product sold online to California

A small business that employs ten or more people sells a metal product through its website to customers in several states. A listed chemical is present in the product, and the business cannot show that the expected exposure is below the safe harbor level. To sell to California customers, the business needs to give a Proposition 65 warning that reaches the buyer before purchase, such as on the product page, and one on the product or its packaging. It also needs to coordinate with any retailers that carry the product. The safety data sheet might mention the chemical in Section 15, but the sheet is aimed at workplace users and is not a substitute for the consumer warning.

Frequently asked questions

What is Proposition 65?

A California law that requires businesses to warn Californians about significant exposures to chemicals on a list of those known to cause cancer or reproductive harm.

Does a Prop 65 warning mean the product is dangerous?

Not necessarily. It means the product contains a listed chemical and the business could not show that exposure is below the safe harbor level or is exempt. It is a notice, not a ban.

Does Prop 65 apply outside California?

It applies to exposures in California, so it affects businesses that sell products there, wherever they are based.

Is Prop 65 information required on an SDS?

No. SDS content on Prop 65 is voluntary, though many suppliers include it in Section 15.

Reference only. This page is general education, not legal advice and not a replacement for the safety data sheet, label and procedures that come with the product you use or for the text of the regulation itself. Have an SDS you want explained? Try the AI SDS analyzer.