Updated June 14, 2011
With the addition of eight more substances, the National Institutes of Health's (NIH) Report on Carcinogens now lists 240 chemicals and biological agents that may or definitely cause an increased risk of cancer.
The NIH's Report on Carcinogens, is required by Congress as a key function of the National Toxicology Program (NTP). The report identifies "agents, substances, mixtures, and exposure circumstances that are known or reasonably anticipated to cause cancer in humans."
New listings in the Report on Carcinogens for 2011 included two substances known to cause cancer and 6 substances reasonably anticipated to cause cancer.
Known to Cause Cancer
Added to the latest Report on Carcinogens as substances now known to cause cancer in humans were formaldehyde and botanical products containing aristolochic acids.
Formaldehyde: Aside from being the source of controversy in those mobile homesFEMA provided after Hurricane Katrina, formaldehyde is a "colorless, flammable, strong-smelling chemical that is widely used to make resins for household items, such as composite wood products, paper product coatings, plastics, synthetic fibers, and textile finishes," according to the NTP. Formerly listed as a substance reasonably anticipated to cause cancer, formaldehyde was elevated to the status of a known cancer-causing substance after being shown to cause nasal cancer in rats.
Aristolochic Acids: Aristolochic acids occur naturally in some plant species and are sometimes found in herbal products used for the treatment of ailments and diseases like arthritis and gout. Despite a 2001 Food and Drug Administration warning advising against the use of herbal products that might contain aristolochic acids, they can still be purchased on the Internet and abroad, according to the NTP.Reasonably Anticipated to Cause Cancer
Added to the Report on Carcinogens as substances that are "reasonably anticipated" to be cancer-causing were; captafol, cobalt-tungsten carbide (in powder or hard metal form), certain inhalable glass wool fibers, o-nitrotoluene, riddelliine, and styrene.
The NTP notes that riddelliine should not be confused with the drug Ritalin, prescribed for the treatment of attention deficit hyperactivity disorder (ADHD). Riddelliine is found in plants of the genus Senecio, a member of the daisy family, including ragwort and groundsel. According to the NTP, at least 13 species of Senecio have been found in herbal medicines, and in teas and honey.
More About the Report on Carcinogens
Complete details on these and all of the 240 substance listed in the Report on Carcinogens is included in the new report. The complete Report on Carcinogens (5.5 mb) and individual sections are available on the National Toxicology Program's web site.
It should be stressed that the listing of a substance in the Report on Carcinogens does not mean that exposure to it will actually cause cancer. As the NTP notes, several other factors, "including the amount and duration of exposure, and an individual's susceptibility to a substance," will determine the likely hood of developing cancer.
"Reducing exposure to cancer-causing agents is something we all want, and the Report on Carcinogens provides important information on substances that pose a cancer risk," said Linda Birnbaum, Ph.D., director of the National Toxicology Program in a press release.