The U.S. Department of Health and Human Services (HHS) has issued the “12th Report on Carcinogens,” a public-health document that Congress requires the National Toxicology Program to prepare. The report lists eight substances as either “known to be human carcinogens” or “reasonably anticipated to be human carcinogens.” Listing in the report is not itself a regulatory action, but can spur such action by federal, state and international regulatory bodies.

The report classifies formaldehyde and aristolochic acids as known human carcinogens, while listing styrene, captaful, cobalt-tungsten carbide (in powder or hard-metal form), certain inhalable glass wool fibers, ortho-nitrotoluene, and riddelline as reasonably anticipated human carcinogens. According to press reports, several environmental and industry groups may challenge the report’s classifications. See BNA Daily Environment Report, June 13, 2011.