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CA Proposes NSRL for Antimony Trioxide Under Prop 65

California State House

California's Office of Environmental Health Hazard Assessment (OEHHA) published a notice of proposed rulemaking on August 26 that would establish a Proposition 65 No Significant Risk Level (NSRL) for antimony trioxide. OEHHA's proposal would set the NSRL for antimony trioxide at 0.13 micrograms per day.

Proposition 65 requires companies to provide warning statements where their products cause an “exposure” to carcinogens and/or reproductive toxicants, unless an exemption or exception under the law applies. Warnings are not required for exposures below a safe harbor level developed by OEHHA. OEHHA reports the safe harbor level as a NSRL for chemicals listed as causing cancer and as a Maximum Allowable Dose Level (MADL) for chemicals listed as causing reproductive harm.

OEHHA has solicited public comments on the proposed NSRL for antimony trioxide. Comments will be accepted until October 11, 2022.