Eight More Substances Bring total to 256.

• Position: REPORT ON CARCINOGENS

Eight substances have been added to the Report on Carcinogens, bringing the total to 256 that are known, or reasonably anticipated, to cause cancer in humans. This is the 15th Report on Carcinogens, which is a cumulative report, mandated by Congress and prepared by the National Toxicology Program (NTP) for the Secretary of the Department of Health and Human Services.

In the report, chronic infection with the bacterium Helicobacter pylori is listed as known to be a human carcinogen. The flame-retardant chemical antimony trioxide and six haloacetic acids (HAAs) found as water disinfection byproducts are listed as reasonably anticipated to be human carcinogens.

"Cancer affects almost everyone's life, either directly or indirectly," says Rick Woychik, director of the National Institute of Environmental Health Sciences and NTP. "As the identification of carcinogens is a key step in cancer prevention, publication of the report represents an important government activity towards improving public health."

The Report on Carcinogens identifies many different environmental factors, collectively called substances, including chemicals; infectious agents, such as viruses; physical agents, such as X-rays and ultraviolet radiation; and exposure scenarios. A substance is listed either as known to be a human carcinogen or reasonably anticipated to be a human carcinogen, to indicate the potential hazard.

The report does not include estimates of cancer risk because many factors affect whether a person will develop cancer. Those include the carcinogenic potency of the substance, the level and duration of exposure, and an individual's susceptibility to the carcinogenic action of the substance.

H. pylori is a bacterium that colonizes in the stomach and can cause gastritis and peptic ulcers. Most people do not show symptoms. Chronic infection may lead to stomach cancer and a...