On October 21, 2016, the California Environmental Protection Agency’s (CalEPA) Office of Environmental Health Hazard Assessment (OEHHA) added Pentachlorophenol and By-Products of its Synthesis (Complex Mixture) to the list of chemicals known to the state to cause cancer for purposes of Proposition 65. The listing of pentachlorophenol and by-products of its synthesis (complex mixture) is based on formal identification by the National Toxicology Program (NTP), an authoritative body, that the chemical causes cancer. The criteria used by OEHHA for the listing of chemicals under the “authoritative bodies” mechanism can be found in Title 27, Cal. Code of Regs., section 25306.
The chemical pentachlorophenol has been listed under Proposition 65 as known to cause cancer since January 1, 1990. This listing pertains to the complex mixture containing both pentachlorophenol and one or more compounds formed as by-products of pentachlorophenol synthesis.