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Friday, July 18, 1997, 12:00 p.m. EDT
The National Toxicology Program today announced plans to review data that could "de-list" saccharin from the federal government's official report of cancer-causing substances, The Report on Carcinogens, ninth edition.
The NTP, which is headquartered at the National Institute of Environmental Health Sciences in Research Triangle Park, N.C., also announced it intended to review, for official listing, smokeless tobacco (snuff and chewing tobacco) as well as tobacco smoke as a whole and UV radiation, whether from the sun or tanning machines. Some individual chemicals contained in tobacco smoke are already listed.
Data on sulfuric acid mist-used in making products ranging from rayon to paper, rubber and steel-would also be reviewed.
Listings do not themselves constitute regulatory action. However, they often lead to action by federal and state regulatory agencies. This action can range from a ban on the substance to required precautions in their use, such as the use of protective clothing, or special safety or warning labels.
Saccharin has never been listed as a "known" human carcinogen but, since 1981, has been in a lesser category as "anticipated" to be a carcinogen (or "likely to be") based on evidence that included testing in animals. The review aimed at removing saccharin, which is being sought by the Calorie Control Council, an industry group, would be carried out under revised criteria and review procedures announced by the Department of Health and Human Services last year. The criteria were broadened to allow consideration of such factors as mechanisms of action as well as the standard two-year rodent tests, and also set up a mechanism for petitioning to have a substance removed. Under a Congressional mandate, the HHS Secretary is required to submit to Congress a Report on Carcinogens. The Secretary has delegated responsibility for preparing the report on the NTP.
A Canadian study in rats led the Food and Drug Administration to take steps to partially ban the popular sweetener in 1977, but Congress stepped in to permit saccharin's continued sale as long as it is labeled, "Use of this product maybe hazardous to your health. This product contains saccharin which has been determined to cause cancer in laboratory animals."
If the planned review should lead to the removal of saccharin from the federal government's list of known and likely carcinogens, Congress might drop its warning label requirement.
In announcing plans for the ninth such report, NTP said that besides reviewing saccharin for de-listing, it planned to review 13 substances or categories of substances that have been nominated for review as candidates for listing.
Besides tobacco smoke, smokeless tobacco and UV radiation, the substances planned for review are:
- Benzidine-based dyes-a class of more than 250 dyes primarily used to dye textiles, leather and paper;
- Chloroprene, used to make industrial rubber products and as a component of adhesives in food packaging;
- Phenolphthalein, an ingredient in some nonprescription laxatives which a study by the National Institute of Environmental Health Sciences already has caused the Food and Drug Administration to review its use as a nonprescription drug;
- Sulfuric acid mist, used to make fertilizers, rayon and other fibers, pigments and colors, explosives, plastics, coal-tar products such as dyes and drugs, storage batteries, detergents, rubber, pulp and paper, cellophane and catalysts. It is also used in refining petroleum, in ore concentration and in removing impurities from iron, steel and other metals;
- Tetrafluoroethylene, which is used in making Teflon and was used as a propellant in food and cosmetic aerosols;
- Trichloroethylene, an industrial solvent for vapor degreasing and cold cleaning fabricated metal parts. It has also been used as a carrier in insecticides and fungicides-and was once commonly used to decaffeinate coffee but has been replaced by a water process;
- Tamoxifen, a drug used in the palliative treatment of breast cancer and in preventing recurrence. (As with many cancer drugs, the labeling already reflects studies indicating the drug may sometimes also cause cancer in animals or humans.)
In addition, several already listed substances would be reviewed as candidates to move from "anticipated" human carcinogens to the stronger category of "known" human carcinogens:
- Butadiene, a chemical used in making synthetic rubber (and already regulated);
- Cadmium and cadmium compounds, used in batteries, alloys, coating and plating, plastic and synthetic products;
- Dioxin, or tetrachlorodibenzo-p-dioxin (TCDD), formed as an impurity or byproduct in herbicide manufacture, as in the Agent Orange sprayed by the U.S. military to defoliate parts of Vietnam, and during incineration and in several industrial processes.
Saccharin, which provides a sweet taste without the calories of sugar, became the first artificial sweetener after it was discovered by two chemists in 1879. One of them, Constantin Fahlberg, discovered the sweet taste by accident. According to the Britannica, he noticed an unexpected sweet taste to food he subsequently ate, and found this sweetness on his hands and arms, though he had washed them thoroughly. By taste tests back in his laboratory he found the source of the sweetness was saccharin. (It is 200 to 500 times as sweet as cane sugar.)
Saccharin became widely used by diabetics and was used in drugs in which sugar might lead to spoilage. In the toxicological studies that led to FDA's proposed ban, saccharin fed to rats at levels of 5 to 7.5 percent of their diet had a greater incidence of bladder cancer. Later, studies of human saccharin users showed no link to human bladder cancer. Most countries continued to permit its use-often with a label mentioning the animal studies. In recent years, saccharin has had strong competition from aspartame and other new synthetic sweeteners.
In an announcement in the Federal Register July 11, public comments and scientific input were invited for 45 days. These should be sent to Dr. C. W. Jameson, National Toxicology Program, Report on Carcinogens, Mail Drop EC-14, PO Box 12233, Research Triangle Park, NC 27709.
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