On February 27, 2015, the California Office of Environmental Health Hazard Assessment published a Notice of Intent to List styrene as a Proposition 65 carcinogen under the authoritative bodies mechanism. This is the third time that OEHHA has attempted to list styrene. Comments on the proposed listing must be submitted by March 30, 2015.
OEHHA first attempted to list styrene in 2009 under the Labor Code mechanism. That proposed listing was challenged in court, on the basis that the underlying scientific conclusion about the chemical’s carcinogenicity, developed by the National Toxicology Program (NTP), was based on “less than sufficient” evidence in animals and therefore did not meet the Proposition 65 statutory requirement for listing. The California Court of Appeal agreed in Styrene Information and Research Center v. Office of Environmental Health Hazard Assessment (2012) 210 Cal.App. 4th. 1082, and styrene was not listed.
OEHHA again proposed listing styrene in 2013 via the Labor Code mechanism, premised on NTP’s 2011 Report on Carcinogens (RoC). That proposed listing was later withdrawn.
OEHHA’s latest attempt to list styrene also is based on the NTP’s 2011 RoC, but is being proposed via the authoritative bodies mechanism rather than the Labor Code mechanism. The underlying studies purportedly demonstrate that mice develop lung tumors by both inhalation and oral routes of exposure.
Styrene is used extensively in the manufacture of plastics, rubber and resins. The federal Environmental Protection Agency has stated that the general population may be exposed to styrene from building materials and consumer products, with inhalation as the primary route of exposure. If this third attempt to list styrene succeeds, it will undoubtedly result in a tidal wave of enforcement actions by Proposition 65 bounty hunters.