Directed by Congress to conduct an independent review of the styrene assessment in the National Toxicology Program’s (NTP’s) 12th Report on Carcinogens (12th RoC), the National Academies National Research Council (NRC) recently issued a report concurring that there is “compelling evidence… to support a listing of styrene as, at a minimum, reasonably anticipated to be a human carcinogen.” Deemed “a substance of interest” because many people are exposed to it through environmental sources, styrene is used in food packaging and “a broad spectrum of products, including latex paints and coatings; synthetic rubbers; construction materials, such as pipes, fittings, and lighting fixtures; packaging; household goods, such as synthetic marble, flooring, and molded furnishings; and automotive parts.”

According to NRC, which reviewed the primary literature cited in the 12th RoC, NTP “adequately documented that exposure to styrene occurs in occupational settings and in the general public regardless of smoking status.” Concluding there was enough evidence based on human, animal and mechanistic studies to support NTP’s conclusion “that styrene should be considered for listing in the RoC,” the council also conducted an independent assessment of styrene supporting this finding. “In sum, the committee finds that compelling evidence exists to support a listing of styrene as, at a minimum, reasonably anticipated to be a human carcinogen,” states the report. “That conclusion is based on credible but limited evidence of carcinogenicity in traditional epidemiologic studies, on sufficient evidence of carcinogenicity in animals, and on convincing evidence that styrene is genotoxic in exposed humans.”