The U.S. Department of Health and Human Services released the 12th Report on Carcinogens  in June 2011.
"The Report on Carcinogens (RoC) is a congressionally mandated, science-based, public health document that is prepared for the HHS Secretary by the National Toxicology Program.
"The report identifies agents, substances, mixtures, and exposure circumstances that are known or reasonably anticipated to cause cancer in humans."
From the press release :
"The industrial chemical formaldehyde and a botanical known as aristolochic acids are listed as known human carcinogens. Six other substances — captafol, cobalt-tungsten carbide (in powder or hard metal form), certain inhalable glass wool fibers, o-nitrotoluene, riddelliine, and styrene — are added as substances that are reasonably anticipated to be human carcinogens. With these additions, the 12th Report on Carcinogens now includes 240 listings."