In June 2011, the National Toxicology Program (NTP) of the U.S. Department of Health and Human Services published its 12th Report on Carcinogens. The report is a scientific and public health document that identifies substances that cause or may cause cancer.

The report is congressionally mandated and classifies substances carcinogenic substances in two categories: “Known to be a Human Carcinogen” and “Reasonably Anticipated to be a Human Carcinogen.” The 12th Report upgraded the classification of formaldehyde from “Reasonably Anticipated to be a Human Carcinogen” to “Known to be a Human Carcinogen.” In addition, the 12th Report newly classified several substances as “Reasonably Anticipated to be a Human Carcinogen,” including cobalt-tungsten carbide, glass wool fibers (fiberglass), ortho-nitrotoluene, and styrene. An addendum to the report states that “the NTP’s decision to list formaldehyde in the 12th RoC as known to be a human carcinogen was the result of a rigorous scientific review process that included many opportunities for public involvement and comment.” The listing was made despite fierce opposition mounted and lobbying by the Formaldehyde Council and other chemical industry organizations.