ENVIRONMENTAL TOBACCO-SMOKE

In 1992, the U.S. Environmental Protection Agency (EPA) issued a "draft" assessment of ETS and lung cancer in adults and respiratory disorders in children. Relying on weak and inconclusive epidemiological data, the supposed similarity between ETS and MS, the presence of "known or suspected carcinogens" in MS and by extrapolation in ETS, and the "biological plausibility" of an adverse relationship between ETS and health, the EPA recommended that ETS be classified as a "Group A (known human) carcinogen." Fundamental physical and quantitative chemical differences among ETS, MS, and SS and human exposure to each smoke were disregarded: The three are not equivalent nor is ETS exposure a quantitative variant of cigarette smoking. A substantial difference in retention percentage overlays the huge dosimetric difference between exposures. As a result, the "dosage" of ETS retained is miniscule relative to MS. Also, conclusions reached by the EPA and the use of tenuous relationships as bases for Group A classification are unwarranted because of failure to consider the data upon which the "tumorigenicity" of the ETS components was based, questions on the presence and/or levels of these components in MS, and data indicating that a 25- to 30-fold decrease of a high-level dose of MS or MS condensate diminished the effects observed in bioassays from pronounced to zero, i.e., a threshold was demonstrated. Finally, EPA overlooked the more than 100 tobacco smoke components known to inhibit the tumorigenic action of many of the listed "tumorigens". © 1992.