The substances are among the new additions to the National Toxicology Program's 10th report on carcinogens, released today by the National Institute of Environmental Health Sciences (NIEHS). The updated version adds 15 entries to the list, bringing the total of known or potential carcinogens to 228. Five of the 15 additions are listed as known cancer-causing agents.
"The public is well served by this dispassionate report that helps all of us ensure that the American public is made aware of potential cancer hazards," said Health and Human Services Secretary Tommy Thompson, whose department oversees the NIEHS.
Christopher Portier, director of the environmental toxicology program, which produces the report every two years, said policy makers use the information to help limit exposures to the hazardous substances. However, by the time an item appears as a known carcinogen, it should already be subject to regulations that shield the public. Items in the less-certain category may be there because of more recent animal studies and thus may not be so tightly controlled.
Here are the new "known human carcinogens":
- Estrogen: The reproductive hormone, a component of hormone replacement therapy, causes breast and uterine tumors. A number of steroidal estrogens had made previous lists as "reasonably anticipated carcinogens," but this is the first report listing all of them as a group.
- Nickel and nickel compounds: The metal causes lung and nasal cancer, chiefly from occupational exposure in refiners and welders.
- Beryllium and beryllium compounds: Another workplace toxin, the element leads to lung cancer.
- Wood dust: Produced in furniture making and other industrial settings, it causes cancer of the nasal cavities.
- Ultraviolet radiation: Ultraviolet light in general is known to cause skin cancer, earning it a spot on the list of known carcinogens. Tanning lamps, which rely on UV radiation, are known carcinogens, Portier said.
Two forms of vinyl also made the list as substances "reasonably anticipated" to cause cancer in people exposed to them on the job. These probable carcinogens already number 176, and include PCBs, urethane and acrylamide, a molecule generated in frying, baking and other high-temperature cooking.
Bill Jameson, an NIEHS toxicologist, said acrylamide has been on the list of likely carcinogens since the sixth report, released in 1991. "We've known for a while that acrylamide is an animal carcinogen," he said. The FDA this month released acrylamide levels in scores of foods, including french fries and potato chips. The agency plans to test hundreds more foods.
The additions have been under consideration for two and a half years, undergoing extensive review by scientists and lengthy public debate. Talc, which was a candidate for the list in 2000, was set aside for additional investigation after an industry outcry convinced experts that calling it a known carcinogen might be a mistake.
"The talc manufacturing and mining industry gave us a very long and clear lecture on why we have not done a good job" with the substance, Portier said. "We're not saying it shouldn't be listed and we're not saying it should. But we didn't do our job adequately."
The NIEHS is now mulling evidence for its 11th report, due in 2004. Among the substances and agents under review are neutrons, workplace lead, and napthalene, an ingredient in mothballs. Three viruses may also be added: hepatitis B and C, which are linked to liver cancer, and human papillomaviruses, which can cause cervical tumors in women.
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