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Grilled Meat Added to List of Cancer Causes

Viruses, Lead, and X-rays Added to Federal Carcinogen List

WebMD Health News

Jan. 31, 2005 -- The number of cancer-causing agents has grown to 246, according to a new government report released today.

Federal health officials added 17 substances to the list of cancer-causing agents, which now includes 58 substances "known" to cause cancer and 188 "reasonably anticipated to be human carcinogens."

For the first time, viruses are included in the report as "known carcinogens": hepatitis B virus, hepatitis C virus, and some human papillomaviruses (HPV). Research has shown that the hepatitis B virus and hepatitis C virus can cause liver cancer, and certain strains of the human papillomavirus cause cervical cancer in women.

Also new to the known carcinogen list are three types of radiation: X-rays, gamma radiation, and neutrons. Studies have shown that exposure to X-ray and gamma radiation is most strongly associated with leukemia and cancer of the thyroid, breast, and lung.

According to the report, of the total worldwide exposure to X-rays and gamma radiation, 55% is from low-dose medical sources such as bone, chest, and dental X-rays, and 43% is from natural sources like radon. Neutron radiation is used less than other types of radiation in industry, medicine, and research; exposure is primarily from radiation from outer space that penetrates the earth's atmosphere.

The risk of developing cancers due to these forms of radiation depends largely on age at the time of exposure. Childhood exposure is mainly responsible for the increased leukemia and thyroid cancer risks; exposure during childbearing years is related to an increased risk of breast cancer, and exposure in later life is related to lung cancer risk.

Medical use of X-rays already includes precautions, such as lead aprons, to reduce the exposure to radiation.

Researchers say one in two men and one in three women will develop cancer at some point in their lifetimes. Studies have shown that environmental factors, such as exposure to the cancer-causing substances listed in the report, can trigger diseases like cancer, especially when someone has a family history.

Carcinogen List Grows

The list is included in the eleventh annual "Report on Carcinogens" issued by the Department of Health and Human Services (HHS). Federal law requires that the report be updated every two years.

Aside from the six substances added to the known carcinogen list, researchers also added 11 substances to the "reasonably anticipated" category:

  • Lead is used to make batteries, ammunition, and cable coverings, and lead compounds are used in paint, glass and ceramics, fuel additives, and in some ethnic and ceremonial cosmetics. Exposure to lead or lead compounds is associated with a small increased risk for lung and stomach cancer in humans and cancer of the kidney, brain, and lung in studies with laboratory animals.
  • Naphthalene is used in the synthesis of many industrial chemicals and has been used as an ingredient in some moth repellents and toilet bowl deodorants. Inhalation studies in animals show it causes rare nasal tumors in rats and benign (noncancerous) lung tumors in female mice.
  • MeIQ, MeIQx, and PhIP are compounds formed when meats and eggs are cooked or grilled at high temperatures. These compounds are also found in cigarette smoke. Animal studies show that when taken by mouth they cause cancer in multiple organs including the stomach, colon, liver, oral cavity, mammary gland, skin, and intestine. Several human studies suggest there is an increased cancer risk associated with eating grilled or well-done meats that may contain these or other similar compounds.
  • Cobalt Sulfate is used in electroplating, as coloring agents for ceramics, and as drying agents in inks and paints. Studies in animals show that it causes adrenal gland and lung tumors when inhaled.
  • Diazoaminobenzene is a chemical used in the production of dyes and to promote adhesion of natural rubber to steel. Studies show that it is metabolized to benzene, a "known human carcinogen," and causes genetic damage in laboratory animals.
  • Nitrobenzene is a chemical used mainly in the production of other industrial chemicals. Research shows inhalation of this compound produced cancer in experimental animals.
  • 1-Amino-2, 4-dibromoanthraquinone is a vat dye used in the textile industry. Evidence shows it causes cancer in experimental animals.
  • 4,4'-Thiodianiline is used in the preparation of several kinds of dyes. Studies have shown that it causes cancer in experimental animals.
  • Nitromethane is used in specialized fuels, explosives, and in the synthesis of pharmaceuticals and agricultural chemicals. Research has shown that it causes cancer in experimental animals.

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