The California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA) has announced its intent to list styrene as a chemical known to the state to cause cancer under the authoritative bodies listing mechanism of the Safe Drinking Water and Toxic Enforcement Act of 1986 (Proposition 65). Styrene is used in the manufacture of various consumer products, including polystyrene packaging, synthetic rubber and food containers.

Two previous attempts to list styrene as known to cause cancer under Prop. 65’s Labor Code listing mechanism failed. The agency’s latest attempt relies on findings in the National Toxicology Program’s (NTP’s) 2011 Report on Carcinogens, which concluded that styrene is “reasonably anticipated to be a human carcinogen” based on studies showing that inhalation and oral exposure to the chemical increased the incidence of malignant and combined incidence of benign and malignant lung tumors in male and female mice. The National Research Council confirmed NTP’s findings on the carcinogenicity of styrene in a 2014 review.

OEHHA is accepting public comments about whether styrene meets the criteria for authoritative bodies listings until March 30, 2015. See OEHHA News Release, February 27, 2015.