Prop 65 Warnings Explained: What They Mean and Who Must Give Them
What a Prop 65 warning means, which businesses must give one, the safe harbor levels, the 2028 short-form deadline and what violations cost.
A Prop 65 warning tells you a product or place can expose you to one of about 900 chemicals California lists as causing cancer, birth defects or other reproductive harm. Businesses with 10 or more employees must give one unless the exposure is below the safe harbor level. Violations cost up to $2,500 per violation per day, and the short-form label must name a chemical by January 1, 2028.
What Prop 65 is
Proposition 65, the Safe Drinking Water and Toxic Enforcement Act, passed in November 1986. It does two things. It requires a "clear and reasonable" warning before a business knowingly exposes anyone in California to a listed chemical, and it bars businesses from knowingly discharging listed chemicals into sources of drinking water. The Office of Environmental Health Hazard Assessment (OEHHA) keeps the list, which it must update at least once a year.
The list mixes industrial chemicals, pesticides, drugs and things people encounter every day: lead, acrylamide in fried and baked foods, alcoholic drinks, tobacco smoke and gasoline exhaust are all on it.
What a warning does and doesn't mean
A warning means the business knows or believes there's an exposure to a listed chemical. It doesn't mean the product is illegal or fails a safety standard, and businesses don't file reports with OEHHA about why they warn. Some warn without testing just to avoid lawsuits, which is why the labels are everywhere. To find out what's in a product and at what level, ask the business that put the warning on it.
Which businesses must warn
- Size: 10 or more employees. Smaller businesses and government agencies are exempt from both the warning rule and the discharge ban.
- Exposure: a warning is needed only if the exposure is above the "no significant risk" level for a carcinogen (no more than one extra cancer case in 100,000 people exposed for 70 years) or above 1/1,000 of the no-observable-effect level for a reproductive toxicant.
- Safe harbor levels: OEHHA has published more than 300 numeric levels that tell businesses where the line is. For chemicals without one, the business has to prove the exposure is low enough, or warn.
- Newly listed chemicals: businesses get 12 months after a listing to start warning and 20 months to stop discharges.
The warning itself
OEHHA's regulations give "safe harbor" warning formats: if a business uses one, the warning is deemed clear and reasonable. The full-length warning names a chemical and points to www.P65Warnings.ca.gov. The short-form version, for small labels, used to skip the chemical name.
That changed on January 1, 2025. A short-form warning must now name at least one listed chemical (for example, a cancer warning names a carcinogen in the product), and businesses can use "CA WARNING" or "CALIFORNIA WARNING" as the signal word. Businesses using the old short form have until January 1, 2028 to switch, and products manufactured and labeled with the old wording before then can be sold indefinitely. Online sellers get 60 days to update a website warning after a manufacturer tells them about a change.
Enforcement and penalties
The Attorney General enforces Prop 65, and so can any district attorney, the city attorney of a city with more than 750,000 people, and any private person acting in the public interest. Penalties run up to $2,500 per violation per day. Private enforcers must first send a 60-day notice to the business and to public prosecutors; if no prosecutor takes the case, the private party can sue. Most cases end in settlements that require warnings or reformulation.
Check your business
The Prop 65 Warning Checker covers the employee threshold, the exposure test and the safe harbor options for your product or location. For other rules that apply when you sell to Californians, see the Junk Fee Compliance Checker and the Seller's Permit Checker.
Frequently Asked Questions
What does a Prop 65 warning mean?
It means the business believes the product or place can expose you to at least one of about 900 chemicals California lists as causing cancer, birth defects or other reproductive harm. It does not mean the product breaks any safety standard, and businesses don't report the exposure level to the state.
Which businesses have to give Prop 65 warnings?
Any business with 10 or more employees that knowingly exposes people in California to a listed chemical above its safe harbor level. Businesses with fewer than 10 employees and government agencies are exempt.
What is the Prop 65 penalty?
Up to $2,500 per violation per day. The Attorney General, district attorneys, city attorneys of cities over 750,000 people and private individuals acting in the public interest can all sue. A private plaintiff must first send a 60-day notice of violation.
What changed in the Prop 65 short-form warning?
Amendments effective January 1, 2025 require the short-form warning to name at least one listed chemical and allow "CA WARNING" or "CALIFORNIA WARNING" as the signal word. Businesses using the old short form have until January 1, 2028 to switch, and products labeled before then can keep selling.
Why do I see Prop 65 warnings outside California?
Many manufacturers can't tell which units will end up in California, so they label everything. The new optional "CA WARNING" signal word is meant to show that the warning is a California requirement.
This article is for general information only and is not legal advice. Prop 65 compliance turns on facts about specific products and exposures; talk to a qualified professional before relying on it. Sources: OEHHA, About Proposition 65 and Proposition 65 in Plain Language; OEHHA Final Statement of Reasons for the short-form warning amendments (October 2024); Health and Safety Code 25249.5-25249.13; Title 27 California Code of Regulations, Article 6.