Styrene Listed Effective April 22, 2016 as Known to the State of California to Cause Cancer

Effective April 22, 2016, the Office of Environmental Health Hazard Assessment (OEHHA) is adding styrene (CAS No. 100-42-5) to the list of chemicals known to the state to cause cancer for purposes of the Safe Drinking Water and Toxic Enforcement Act of 1986 (Proposition 65^[1]). 

The listing of styrene is based on formal identification by the National Toxicology Program (NTP), an authoritative body^[2], 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 documentation supporting OEHHA’s determination that the criteria for administrative listing have been satisfied for styrene is included in the Notice of Intent to List posted on OEHHA’s website and published in the February 27, 2015 issue of the California Regulatory Notice Register (Register 2015, No. 9-Z).  OEHHA received 13 public comments on the Notice of Intent to List.  The comments and OEHHA’s responses are posted with the Notice of Intent to List.

A complete, updated chemical list will be published in the California Regulatory Notice Register and is available on the OEHHA website.  In summary, styrene is listed under Proposition 65 effective April 22, 2016 as known to the state to cause cancer, as follows:

^* Listing mechanism:  AB – “authoritative bodies” mechanism (Title 27, Cal. Code of Regs. section 25306).