Proposition 65 Clear and Reasonable Warning Requirements

Proposition 65 warning requirements apply to any business with ten or more employees that exposes people in California to one of roughly 900 chemicals the state has identified as causing cancer, birth defects, or reproductive harm.¹ To be compliant, the warning has to follow the state’s “safe harbor” format, reach the consumer or bystander before the exposure happens, appear in the right languages, and come from the right party in the supply chain. The rules cover products sold in California, workplaces located there, and environmental discharges alike.

When a Warning Is Actually Required

Not every trace of a listed chemical triggers the duty to warn. The Office of Environmental Health Hazard Assessment (OEHHA) publishes safe harbor exposure levels: No Significant Risk Levels (NSRLs) for carcinogens and Maximum Allowable Dose Levels (MADLs) for reproductive toxicants. Exposure at or below those levels does not require a warning.²

Businesses can also rely on alternative exposure levels if they can demonstrate scientific validity, but the safe harbor thresholds are the cleanest path. Where a product creates exposures through more than one route, the doses are combined by formula rather than assessed one at a time.²

When OEHHA adds a new chemical to the list, the warning obligation does not start immediately. Businesses have one year from the listing date to comply. The separate ban on discharging listed chemicals into drinking water sources kicks in after 20 months.³

What a Safe Harbor Warning Must Contain

A warning that follows the safe harbor format under Title 27, California Code of Regulations, Section 25603 is presumed to be “clear and reasonable.” Every compliant consumer product warning includes four elements:

A warning symbol: a black exclamation point inside a yellow equilateral triangle with a bold black outline. On labels or signs not printed in color, a black-and-white version is acceptable. The symbol must be at least as tall as the word “WARNING.”⁴
The word “WARNING:” in bold capital letters. “CA WARNING:” or “CALIFORNIA WARNING:” also works.⁴
At least one named chemical for each type of harm present (cancer, reproductive toxicity, or both).
A reference directing consumers to www.P65Warnings.ca.gov.⁴

Required Phrasing by Risk Type

The exact wording depends on which health effects the product’s chemicals pose:

Cancer only: the warning states that the product can expose you to chemicals including the named chemical, which is known to the State of California to cause cancer.⁴
Reproductive harm only: the named chemical is identified as known to cause birth defects or other reproductive harm.
Both risks: a combined statement names a chemical for each category. If a single chemical is listed for both, name it once and identify both risks.

Getting a word wrong in the prescribed language can strip the safe harbor and expose a business to arguments that the warning was not clear and reasonable. Most compliance teams work directly from OEHHA’s sample warnings rather than drafting their own.

Short-Form Warnings for Small Labels

When a product label has limited space, a condensed warning is allowed. The short form still needs the triangle symbol and the bold “WARNING:” header, but the body text is compressed. A cancer-only short-form warning reads: “Can expose you to [chemical name], a carcinogen. See www.P65Warnings.ca.gov.” Reproductive-toxicity and combined versions follow the same pattern.⁴

Short-form warnings are only permitted on the product label. They do not satisfy the requirement for shelf signs, websites, or catalogs. Even in short form, the type must be at least 6 points and no smaller than the largest font used for other consumer information on the label.⁵

How the Warning Has To Reach People

Products Sold In Stores

The straightforward option is a warning on the container or wrapper. If direct labeling is not practical, a shelf tag or point-of-sale sign works, provided it sits close enough to the product that a shopper would see it before buying.⁵ A sign tucked behind a display does not qualify.

Online Sales

For internet purchases, the warning must appear before checkout. Acceptable delivery methods include showing the full warning on the product page, a clearly labeled hyperlink using the word “WARNING” that leads to the warning text, or a prominent notice presented before the purchase is finalized.⁵ Burying the warning in terms of service does not comply.

Catalog Sales

Mail-order and telephone catalogs must place the warning near the item description so buyers see it before ordering. A general disclaimer at the back of the catalog is not enough.⁵

Buildings and Other Environmental Exposures

For places like parking garages, industrial facilities, or buildings where listed chemicals are present, warning signs must be posted at every public entrance, conspicuous enough to be seen before entering. If other signage in the area uses a language besides English, the Proposition 65 warning must also appear in that language.³

Workplaces

For chemicals covered by the federal Hazard Communication Standard or California’s equivalent, a warning that fully complies with those labeling, information, and training requirements also satisfies Proposition 65.⁶ For chemicals not covered by those hazard communication rules, the standard consumer warning format applies.

Language and Size

Every warning must be in English. It must also appear in any other language used elsewhere on the label or signage for “consumer information,” meaning things like ingredient lists, directions for use, and nutrition panels. Brand names, company names, and advertising slogans do not trigger the translation requirement.³ A product with Spanish-language use instructions needs a Spanish warning; a product with only a Spanish brand name does not.

Warning text must be at least as large as the biggest font used for other consumer information on the label, and never smaller than 6-point type.⁵ The triangle symbol sits to the left of the text and must be at least as tall as the word “WARNING.”⁴

Alcoholic Beverages Have Extra Rules

Alcohol carries display requirements on top of the standard safe harbor. Bars, restaurants, and other on-sale establishments must post a 10-inch by 10-inch black-and-white notice at every public entrance where alcohol is served. Off-sale retailers such as liquor stores must display a 5-inch by 5-inch red-and-white sign at each checkout counter.⁷ These signs are enforced through the Department of Alcoholic Beverage Control in addition to the standard framework.

Who in the Supply Chain Is Responsible

The obligation to warn does not fall equally on everyone who touches the product. Primary responsibility rests with the businesses farthest upstream: the manufacturer, producer, packager, importer, or distributor. Those businesses must either place the warning directly on the product or send written notice and warning materials to the retailer (or the retailer’s authorized agent) and receive acknowledgment that the materials were delivered.³

Retailers are responsible for placing and maintaining the warning materials they receive. If a retailer first learns that a product requires a warning because it received a 60-day enforcement notice, it has five business days to add a warning or pull the product from the shelves.³ That cure window is narrow and not a compliance plan.

Component and ingredient suppliers have a related obligation. If a component maker knows its part typically ends up in a consumer product and could cause a listed-chemical exposure, it should provide warning materials to the purchasing manufacturer, which then decides whether the finished product needs a warning.³

What Happens if You Get It Wrong

Proposition 65 is enforced heavily by private plaintiffs, not just the Attorney General. Before filing suit, a private enforcer must serve a 60-day notice on the alleged violator, the California Attorney General, and the local district attorney or city attorney for the jurisdiction where the violation occurred. A failure-to-warn notice must include a certificate of merit signed by the noticing party or their attorney, stating that they consulted with someone with relevant expertise, reviewed the facts and data, and believe the claim has merit.⁸

After the 60-day window, the private plaintiff can sue, but only if none of the government prosecutors has already stepped in. Civil penalties run up to $2,500 per violation per day, and each day of a continuing violation counts separately.⁸ Most enforcement actions settle, with settlements typically covering a civil penalty, the enforcer’s attorney fees, and compliant warnings going forward. The combination of daily penalties and fee-shifting is what keeps the enforcement pipeline active, and it is the reason a properly built warning at the start almost always costs less than fixing one after a notice arrives.

1
California Legislative Information. California Health and Safety Code HSC 25249-6
2
Office of Environmental Health Hazard Assessment. Proposition 65 No Significant Risk Levels NSRLs and Maximum Allowable Dose Levels MADLs
3
Proposition 65 Warnings. Frequently Asked Questions for Businesses
4
Legal Information Institute. California Code of Regulations Title 27 25603 – Consumer Product Exposure Warnings – Content
5
Legal Information Institute. California Code of Regulations Title 27 25602 – Proposition 65 Clear and Reasonable Warning Requirements
6
Legal Information Institute. California Code of Regulations Title 27 25606 – Occupational Exposure Warnings
7
California Department of Alcoholic Beverage Control. Prop 65 Notice
8
Justia. California Health and Safety Code 25249.5-25249.13 – Safe Drinking Water and Toxic Enforcement Act of 1986