Estrogens top new carcinogens list


WASHINGTON, Dec. 11 (UPI) -- Estrogens, used in hormone-replacement therapy and contained in birth-control pills, have been added to the list of known human carcinogens, a U.S. government report revealed Wednesday.

The report, sent to Congress every two years, lists a total of new 15 substances categorized as "reasonably anticipated" to increase the risk of cancer. The list totals 228 items.


This 10th edition of the report was prepared by the National Toxicology Program, a branch of the Department of Health and Human Services at the National Institute of Environmental Health Sciences, one of the National Institutes of Health. Three panels of government and non-government scientists reached their conclusions after reviewing medical literature and data on various substances. Much of data reviewed included animals studies that had linked these substances to increased risks of cancer.

"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," Health and Human Services Secretary Tommy Thompson said in a statement.


Not everyone agrees the report is so helpful to the public, however.

"This new report is fine, however, it's probably at least 10 years late," Dr. Samuel Epstein, professor emeritus of environmental medicine at the University of Illinois at Chicago, told United Press International.

Epstein, who also is chairman of the Cancer Prevention Coalition, added: "This is playing catch-up. What's the reason for the very long period of delay? This is responding and reacting to information that's available on The New York Times, so bravo. We have a very large number of carcinogens that the public is not warned about."

Although many of the carcinogens, such as the chemical 2,3-Dibromo-1-propanol, are not common household words, others are, such as estrogens, wood dust and ultraviolet rays. Broad spectrum ultraviolet radiation, generated by the sun and also by sun lamps and tanning beds, now occupies the list. The report cites data supporting a cause-and-effect between ultraviolet radiation and skin cancer, including melanoma of the eye.

Wood dust, which comes primarily from occupational exposures, such as in saw mills, cabinet making and furniture manufacturing, exposes unprotected workers who inhale the substance have a greater risk of cancer in the nasal passages and sinuses.


The list also includes nickel compounds, which are contained in batteries, ceramics and pigments. According to the report, there is a heightened risk of workers who inhale nickel compounds to develop lung and nasal cancers.

Another substance, 2-amino-3-methylimidazo[4,5-f]quinoline, more commonly known as IQ, is more prevalent than most Americans realize. It is produced when cooking meats or eggs at high heat. It also is found in cigarette smoke. The report cites several animals studies showing IQ exposure increased the risk of breast and colorectal cancers, two of the most common types of cancer afflicting Americans today.

"There is nothing particularly 'new,' from a scientific point, in this report, as all of these substances have long been suspected to increase the risk of cancer in humans, following repeated, long-term exposure," David Eaton, the associate dean for research and a professor of environmental health at the University of Washington in Seattle, told UPI. The estrogens were added, he said, because "recent studies in humans taking synthetic estrogen for years has finally provided the necessary scientific evidence to now include synthetic estrogens as 'known human carcinogens.'"

People need to keep in mind, Eaton said, that the report considers the most dangerous levels of a carcinogen, not tiny amounts from brief exposure.


"As with all carcinogens, it is the dose that makes the poison," he said. For women taking estrogens, "the increased risk of cancer for women who use low doses, or have relatively short periods of treatment, for less than 5 years, is small."

Other items on the list were:

-- beryllium and beryllium compounds;

-- chloramphenicol, an antibiotic restricted in the United States because it has been known to cause fatal blood disorders;

-- 2,3-Dibromo-1-propanol, a chemical used in the production of insecticides, and pharmaceuticals;

-- dyes metabolized to 3,3'-dimethoxybenzidine used to color leather, paper, plastic, rubber and textiles;

-- dyes metabolized to 3,3'-demethylbenzidine, used in printing textiles, in color photography;

-- methyleugenol, a substance found naturally in oils, herbs and spices and is used in natural or synthetic forms in flavorings, insect attractants, anesthetics and sunscreens;

-- metallic nickel, a common industrial metal but not the type used in the nickel coins;

-- styrene7,8-oxide, a chemical used in plastics, cosmetics and in the agricultural and biological industries;

-- vinyl bromide, used in making fabrics for clothes and home furnishings, as well as in leather and metal products, drugs and fumigants; and

-- vinyl fluoride, used to produce polyvinyl fluoride.


Whether this list will have any influence on public policies remains to be seen, said Roberton William, a fellow at the Brookings Institute and a professor of economics at the University of Texas at Austin who studies environmental regulations.

"While being listed may lead to regulation of a particular substance, there is no automatic regulation," William told UPI. "For some substances, just identifying them as carcinogens may well be enough, because it lets individuals make informed decisions."

For example, estrogen therapy, William said, is something women can decide on their own whether they want to be exposed to it or people can choose to avoid tanning beds or protect themselves from sun exposure.

"Individuals don't have a choice about whether to be exposed to the substance or not, and so merely providing the information is not enough," William said. "The government may also have to regulate those substances in order to protect people from them."

Eaton said the NTP findings "are consistent with the prior evaluations of these substances done by International Agency for Research on Cancer." IARC is affiliated with the World Health Organization.

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