U.S. EPA Regulation of Styrene

The U.S. Environmental Protection Agency (EPA) has not given styrene a formal carcinogen classification or listed it as a carcinogen on the Integrated Risk Information System (IRIS) Database, which is a widely used reference for a chemical's potential carcinogenicity.

The current entry for styrene on EPA's Integrated Risk Information System (IRIS) database provides oral and inhalation concentration levels considered to be safe, and states that EPA's cancer classification of styrene for carcinogenic potential is under review. The IRIS is a widely used reference, reflecting EPA's official position with regard to the carcinogenicity or toxicity of a substance. In 2002, the EPA began an IRIS review of styrene health effects information. The results of the review, which are expected to be added to the IRIS database in 2004 or 2005, will determine whether styrene should be classified as a carcinogen and, if so, at what level.

SIRC has met and communicated with EPA staff on numerous occasions to provide reports on the scientific research on styrene as it is completed, and to furnish interim updates. EPA staff has commended SIRC for its willingness to work with the Agency in developing study protocols and in significantly expanding the body of health effects data on styrene, to assist the Agency with its formal hazard assessment for styrene. SIRC continues to monitor EPA program office activity to ensure appropriate treatment of styrene and provide comments on rulemakings when relevant.

NOTE: Within EPA's website there are a variety of interpretations of the health effects of styrene, including lists by certain program offices that identify styrene as a classified carcinogen. SIRC has worked to address and correct these errors; particularly as EPA itself, as well as many of its program offices, look to IRIS as the agency's valid listing of health effects information. Given the fact that opinions listed in program office web pages are not open to public comment, and have not been made based on a review of all available data, SIRC recommends EPA's Integrated Risk Information System as a definitive reference on the health effects of styrene.