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NAS Conducts Independent Review of NTP's Styrene Classification

May 3, 2013

A committee of the National Research Council (NRC) is conducting a scientific peer review of the styrene assessment in the National Toxicology Program (NTP) 12th Report on Carcinogens (RoC). The RoC listed styrene as a substance that is "reasonably anticipated to be a human carcinogen." NTP reserves this category for substances for which there is either limited evidence of carcinogenic effects in humans, or substantial evidence supporting carcinogenicity in experimental animals. The report also includes a separate category for those substances that are "known to be [a] human carcinogen[s]." The latter category applies to substances for which sufficient evidence exists to establish a causal link between exposure and human cancers.

In 2012, at the request of Congress, the U.S. Department of Health and Human Services (HHS) asked the National Academy of Sciences (NAS) to conduct an independent review of the listing, and to evaluate the listing criteria. NAS began its independent review in February 2013. (More information on the review can be found on NAS's website.)

The Styrene Information and Research Center (SIRC) petitioned HHS on March 8, 2012, to include information about the NAS review on the RoC website to make the public aware that the listing is under evaluation. SIRC also challenged the listing in a lawsuit filed against HHS in June 2011, which claims the listing is unsupported by science. The court has yet to issue a ruling.