List of Cancer-Causing Agents Grows

The Department of Health and Human Services released its Eleventh Edition of the Report on Carcinogens on January 31, 2005, adding seventeen substances to the growing list of US recognized cancer-causing agents, bringing the total to 246.

"Among U.S. residents, 1 in 2 men and 1 in 3 women will develop cancer at some point in their lifetimes. Research shows that environmental factors trigger diseases like cancer" said Kenneth Olden, Ph.D., outgoing director of the National Institute of Environmental Health Sciences and the National Toxicology Program, which prepared the report for HHS.

The Report on Carcinogens, Eleventh Edition, referred to as the "RoC," lists cancer-causing agents in two categories -- "known to be human carcinogens" and "reasonably anticipated to be human carcinogens." The report now contains 58 "known" and 188 "reasonably anticipated" listings.

Six substances have been added to the "known" category. One newly added listing has occupational importance:

Hepatitis B virus (HBV) and hepatitis C virus (HCV) are viruses that cause acute or chronic liver disease. They are listed in the report as "known human carcinogens" because studies in people show that chronic hepatitis B and hepatitis C infections cause liver cancer. Infections can be prevented by reducing contact with contaminated fluids in health care settings and, for hepatitis B, by vaccination.

Already listed known human carcinogens of occupational significance include: Arsenic Compounds; Inorganic arsenic; Asbestos; Benzene; Beryllium and Beryllium Compounds; 1,3-Butadiene; Cadmium and Cadmium Compounds; Chromium Hexavalent Compounds; Coal Tar Pitches; Coal Tars; Coke Oven Emissions; Ethylene Oxide; Mineral Oils (Untreated and Mildly Treated); Nickel Compounds Silica, Crystalline (Respirable Size); Soots; Strong Inorganic Acid Mists Containing Sulfuric Acid; Vinyl Chloride; and Wood Dust.

Eleven substances have been added to the "reasonably anticipated" category. Those of occupational importance include:

Naphthalene which may be present in petroleum oils. Naphthalene is listed in the report as "reasonably anticipated to be a human carcinogen," based on inhalation studies in animals which showed it causes nasal tumors in rats and lung tumors in female mice.

Lead is used to make lead-acid storage batteries, lead compounds are used in paint, glass and ceramics, fuel additives. It is a widespread contaminant. The report lists lead and lead compounds as "reasonably anticipated to be human carcinogens" because exposure to lead or lead compounds is associated with an increased risk for lung or stomach cancer in humans, and cancer of the kidney, brain or lung in studies with laboratory animals.

Cobalt Sulfate is used in electroplating, as coloring agents for ceramics, and as drying agents in inks and paints. Cobalt sulfate is listed as "reasonably anticipated to be a human carcinogen" based on inhalation studies in laboratory animals that showed it causes adrenal gland and lung tumors.

Nitromethane is used in specialized fuels. It is listed as "reasonably anticipated to be a human carcinogen" based on evidence that it causes cancer in experimental animals.

The Report on Carcinogens, Eleventh Edition, is prepared by the National Toxicology Program, an interagency group coordinated by the U.S. Department of Health and Human Services. The full report is available at the NTP website http://ntp.niehs.nih.gov/.
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BrooklynDodger points out that there are two major competing carcinogen lists, the NTP list quoted here in press release, and the International Agency for Research Against Cancer (IARC) list. The number of agents depends on how you count classes of chemicals – “lead compounds” can be a lot of chemicals. The IARC list is more inclusive than the NTP list, because the criteria are different.

BrooklynDodger notes that among the “known” compounds above, OSHA standards taking carcinogenicity into account are lacking for beryllium, nickel, silica, sulfuric acid mist and wood dust, and now going into the hearing stage for chromates.