Warning (Proposition 65)

A Proposition 65 warning is the required notice that a business must provide to individuals before knowingly exposing them to a chemical listed as causing cancer or reproductive harm, when exposure exceeds the applicable safe harbour level (NSRL or MADL). The warning must be ‘clear and reasonable’ as defined in Health & Safety Code §25249.6 and Title 27 CCR §25600 et seq. Proposition 65 warnings may be provided through: product labels; shelf tags or signs at point of sale; on-site signage; catalog or internet website warnings; or direct notification (for workplaces and rental housing). OEHHA’s safe harbour warning regulations provide specific content, format, and transmission requirements that create a presumption of compliance.

California Health & Safety Code §25249.6 (warning obligation); Title 27 CCR §§25600–25900 (warning regulations); OEHHA amendments effective January 1, 2025.

Implementing a Proposition 65 warning is one of two compliance strategies (along with reformulation). Once a decision is made to warn, the warning must meet all applicable regulatory requirements: correct symbol, signal word, chemical name(s), URL, transmission method, timing (before purchase or before exposure), and conspicuousness. Using non-compliant warning formats — even if a warning was intended to be provided — does not protect against enforcement. Businesses should conduct a formal warning compliance audit against the current Title 27 CCR regulations, including the January 2025 amendments.