Safe Harbor Level

A safe harbour level is the exposure threshold below which a Proposition 65 warning is not required. OEHHA establishes two types of safe harbour levels: the No Significant Risk Level (NSRL) for carcinogens — set at the exposure causing no more than one excess cancer case in 100,000 individuals over a 70-year lifetime; and the Maximum Allowable Dose Level (MADL) for reproductive toxicants — set at 1/1,000 of the level showing no observable reproductive effect. Safe harbour levels are optional — businesses may use their own risk assessments instead — but if a product’s exposure is below the safe harbour level, the business is exempt from the warning requirement for that chemical. As of April 2026, OEHHA has established specific NSRLs and MADLs for approximately 300 of the 900+ listed chemicals.

California Health & Safety Code §25249.10; Title 27 CCR §§25701–25723 (NSRL methodology); §§25801–25809 (MADL methodology); §25703 (specific NSRLs); §25805 (specific MADLs).

Safe harbour levels are the primary technical benchmark for Proposition 65 compliance decisions. Businesses should: (1) obtain OEHHA’s published NSRL or MADL for each listed chemical present in their products; (2) conduct product-specific exposure assessments to determine whether exposure exceeds the safe harbour level; and (3) either implement a warning or reformulate if exposure exceeds the threshold. For chemicals without an established NSRL or MADL, businesses must conduct a risk assessment using OEHHA’s published methodology to determine an equivalent threshold.