The "known" category is reserved for those substances for which there is sufficient evidence of carcinogenicity from studies in humans that indicates a cause and effect relationship between the exposure and human cancer.
The "reasonably anticipated" category includes those substances for which there is limited evidence of carcinogenicity in humans and/or sufficient evidence of carcinogenicity in experimental animals.
Conclusions regarding carcinogenicity in humans or experimental animals are based on expert, scientific judgment, with consideration given to all relevant information.
The 9th edition of the Report contains 218 entries. Fourteen of the listings are new. Eight of the new entries are listed as "known to be human carcinogens" and the other six entries as "reasonably anticipated to be human carcinogens." This Report also reclassifies six current listings from "reasonably anticipated" to "known to be human carcinogens".
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has been proposed for upgrade to the "known to be a human carcinogen" category. The proposed listing is currently in litigation. Depending on the outcome of the litigation, an addendum may be published following the court's ruling. Two additional substances have been removed or delisted from the Report: saccharin and ethyl acrylate.
The new listings in the 9th edition include some agents and substances to which large numbers of people are exposed including environmental tobacco smoke, tobacco smoking, oral use of smokeless tobacco products, alcoholic beverage consumption, diesel exhaust particulates, UV solar radiation, and use of sun lamps and sun beds. The Report's findings are based on three years of study that included three scientific reviews and public comment from scientists, consumers and other interested parties.
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Contact: Sandra Lange
lange@niehs.nih.gov
919-541-0530
NIH/National Institute of Environmental Health Sciences
14-May-2000