Science Has Advanced
“However, our understanding of the science has advanced and allows us to make finer distinctions today. Studies now indicate that the rat bladder tumors arise from mechanisms that are not relevant to the human situation.”
     He also said humans had used saccharin for decades without increasing rates of cancer.
     The NIEHS also removed ethyl acrylate, a substance used in making latex paints and textiles, from the list. Both were removed at the request of industry groups.
     The report listed 218 substances known or suspected to cause cancer in people. The NIEHS said 14 had either been upgraded to the “known” category or added to the list.

Smoke Tops the List
Secondhand smoke topped the upgraded list. “Environmental tobacco smoke, generated from sidestream and exhaled mainstream smoke of cigarettes, pipes, and cigars is listed as a ‘known human carcinogen,’” said the report.
     It cited reports that showed secondhand smoke can cause lung cancer, as well as studies showing that nonsmoking wives and co-workers of smokers have higher rates of lung cancer.
     Tobacco smoke was also listed as a known cause. “Separate chemicals identified in tobacco smoke were already listed as carcinogens in the report,” it said. The new listing came after 1996 revisions in the review process.
     Smokeless tobacco, including chewing tobacco and snuff, were listed, as well as consumption of alcohol, too much sun and the use of tanning beds or sun lamps.

Alcohol Associated With Some Cancers
Alcohol is associated with cancers of the mouth, pharynx, larynx, and esophagus, and there may be a link with liver and breast cancer. Chewing tobacco and snuff can cause cancer wherever they contact the mouth or nose.
     Other substances listed included:
     Crystalline silica dust small enough to breathe, a byproduct of mining.
     Strong inorganic acid mists containing sulfuric acid, produced in the manufacture of alcohol, lead batteries, phosphate fertilizers, soap and detergents, synthetic ethanol, and in pickling and other acid treatments of metals.
     Dyes metabolized to benzidine.
     1,3-Butadiene, used to make synthetic rubber.
     Cadmium, used in batteries, coating and plating, plastic and synthetic products and alloy.
     Ethylene oxide, used to make other chemicals and to sterilize medical devices.
     Tamoxifen.
     “There has been concern expressed that the listing of tamoxifen … could raise concerns among patients regarding its use for cancer treatment or prevention,” the report said. It pointed out that benefits can outweigh the risks.
     Tamoxifen, made under the name Nolvadex by AstraZeneca, can increase the risk of ovarian cancer. But ovarian cancer is so rare that doctors say the higher risk is small.
     Tamoxifen is the first drug to be shown to prevent breast cancer in some women at high risk.
     Substances added to the “reasonably anticipated to be human carcinogens” list include diesel exhaust particulates, isoprene — one of the components of rubber which is also naturally emitted by plants — chloroprene, phenolphthalein — used in some laxatives — tetrafluoroethylene and trichloroethylene.

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