Cancer Causing Agents - Carcinogens (cont.)
Of the total worldwide exposure to X-radiation and
gamma-radiation, 55 percent is from low-dose medical diagnosis such as bone, chest and
dental X-rays, and 43 percent is from natural sources like radon. Other
sources, such as industry, scientific research, military weapons
testing, nuclear accidents and nuclear power generation, account for
about 2 percent.
- Neutrons are also listed in the report as a "known human
carcinogen." They cause genetic damage similar to that of X-radiation
and gamma radiation, and thus can cause the same cancers. Neutron
radiation is used less than other types of radiation in industry,
medicine, and research. The general population is exposed to neutrons
primarily from cosmic radiation that penetrates the earth's atmosphere.
Eleven substances have been added to the "reasonably anticipated"
- Naphthalene is used as an
intermediate in the synthesis of many industrial chemicals, and has been used
as an ingredient in some moth repellants and toilet bowl deodorants.
Naphthalene is listed in the report as "reasonably anticipated to be a human
carcinogen," based on inhalation studies in animals which showed it causes
rare nasal tumors
in rats and benign lung
tumors in female mice.
- MeIQ, MeIQx, and PhIP are
heterocyclic amine compounds formed when meats and eggs are cooked or grilled
at high temperatures. These compounds are also found in cigarette smoke. They
are listed in the report as "reasonably anticipated to be human carcinogens"
studies in animals showed they caused cancer in multiple organs
including the forestomach, colon, liver, oral cavity, mammary gland,
skin, and cecum. Several human studies suggest there is an increased
risk for breast and colorectal cancers related to
consumption of broiled
or fried foods that may contain these or other similar compounds.
- MeIQ is 2-Amino-3, 4-dimethylimidazo
- MeIQx is 2-Amino-3, 8-dimethylimidazo
- PhIP is 2-Amino-1-methyl-6-phenylimidazo [4,5-b]pyridine
- Lead is used to make
lead-acid storage batteries, ammunition, and cable coverings. Lead compounds
are used in paint, glass and ceramics, fuel additives, and in some ethnic and
ceremonial cosmetics. The report lists lead and lead compounds as "reasonably
anticipated to be human carcinogens" because exposure to lead or lead
compounds is associated with a small increased risk for lung or stomach cancer
in humans, and cancer of the kidney, brain or lung in studies with
- 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.
- Diazoaminobenzene is a
chemical used as an intermediate in the production of dyes and to promote
adhesion of natural rubber to
steel. Diazoaminobenzene is listed as "reasonably anticipated to be a
human carcinogen" based on evidence that it is metabolized to benzene, a
"known human carcinogen," and because it causes genetic damage in
- Nitrobenzene is a chemical used mainly in the production of
other industrial chemicals. It is listed as "reasonably anticipated to
be a human carcinogen" because inhalation studies of this compound
produced cancer in experimental animals.
- 1-Amino-2, 4-dibromoanthraquinone is a vat dye that is used
in the textile industry. It is listed as "reasonably anticipated to be a
human carcinogen" based on evidence that it causes cancer in
- 4,4'-Thiodianiline has been used as an intermediate in the
preparation of several kinds of dyes. It is listed as "reasonably
anticipated to be a human carcinogen" based on evidence that it causes
cancer in experimental animals.
- Nitromethane is used in specialized fuels, explosives, and in
the synthesis of pharmaceuticals and agricultural chemicals. 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.
The National Toxicology Program is located at the
National Institute of Environmental Health Sciences (NIEHS) in Research Triangle
Park, NC. Part of the National Institutes of Health, NIEHS looks at factors in
that may be harmful to human health.
Some of the above information has been provided with the kind permission of the National Institutes of Health
press release #NIEHS PR #05-01, Jan 31, 2005 (www.nih.gov).
Last Editorial Review: 2/1/2005