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Cancer Health Center

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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.

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