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Friday, September 15, 2000, 12:00 p.m. EDT
An expert advisory panel today recommended to the federal government that steroidal estrogens be listed as a "known" cause of cancer in humans in a future NTP Report on Carcinogens (http://ntp.niehs.nih.gov/go/roc).
While panel members said these steroids have important medical uses and clear medical benefits, they have long been associated under certain conditions of use with a risk of uterine and breast cancers. The panel agreed 8 to 1 that these hormones cause an elevated risk and should be considered not merely as associated with increased cancer but as substances that are "known to be a cause of human cancers."
The federal Report on Carcinogens is required by Congress to inform the public, medical community and regulatory agencies about potential cancer-causing substances. It is prepared by the National Toxicology Program (NTP), which is headquartered at the National Institute of Environmental Health Sciences (http://www.niehs.nih.gov) in Research Triangle Park (http://www.rtp.org/) , NC. NIEHS/NTP sought the views of the panel of scientists as one step in the development of the Tenth Report on Carcinogens, which will be written and published after further public comment and review.
Estrogens occur naturally in women and to a lesser degree in men. They have important medical uses in hormone replacement therapies in post-menopausal women and for birth control. Their use has long been associated with a risk of uterine, endometrial and breast cancers. They are so labeled, panelists said, and doctors and women should weigh their known benefits against these risks. There was no suggestion by the panelists that medical use of estrogen be restricted or eliminated.
Another medical product, the antibiotic chloramphenicol, was recommended for listing as "reasonably anticipated" to be a cause of human cancer based on evidence of an association with childhood leukemia. Found to be effective against typhus in 1948, it was one of the first antibiotics in large-scale production but after being linked to a risk of potentially fatal aplastic anemia, the drug's use was limited to cases of typhoid fever and meningitis when other antibiotics were ineffective.
The scientific panel, a part of the National Toxicology Program Board of Scientific Counselors, made its recommendations after three days of discussions (Dec. 13-15) in Washington, D.C.
It also recommended for listing as "known" human carcinogens:
- Common wood dust produced while manufacturing furniture and cabinets as well as other wood products, which is associated in industrial settings with increases in cancer of the nasal cavities and sinuses. About two million people world-wide are exposed to wood dust routinely in their jobs.
- Broad spectrum ultraviolet (UV) radiation from sunlight or artificial sources. However, the individual classes UVA, UVB and UVC were recommended for listing in the different category of "reasonably anticipated to be human carcinogens" because of difficulties in overlaps between classes.
Recommended for listing as "reasonably anticipated to be a human carcinogen":
- Methyleugenol, a naturally occurring component of may herbs and spices including basil, cinnamon, nutmeg and mace. It is also used as a flavoring agent in minute quantities to some jellies, baked goods, nonalcoholic beverages, chewing gum, candy and other foods. Methyleugenol has been linked to liver, glandular stomach, kidney and mammary gland tumors in laboratory animals but no studies have yet been conducted to see if it causes cancer in humans, NIEHS/NTP staff said.
- Metallic nickel as encountered in some industrial uses. But the panel voted against also listing certain alloys of nickel as well. The alloys have many uses as specialty steels and stainless steels and are used in some medical implants.
Trichloroethylene (TCE), a degreaser for metal parts such as those used in manufacturing metal products, electrical and electronic equipment and for cleaning transport equipment, was considered for upgrading to "known" human carcinogen from "reasonably anticipated" but the panel recommended that the chemical continue in the second category.
The panel recommended, 7 to 3, that ordinary talc not be listed as a human carcinogen. The panel reviewed a series of studies of women with ovarian cancer but was not convinced that the excess cancers could clearly be related to genital talc use.
A particular type of talc, called talc with asbestiform fibers, contains fibers that have an appearance similar to asbestos but are not asbestos. The panel rejected a recommendation that these materials be listed as "known human carcinogens," and the panel split, 5 to 5, over whether the data on lung cancers in talc workers justified a listing as "reasonably anticipated to be a human carcinogen."
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