Chemical constituents and bioactivity of tobacco smoke.

Tobacco smoke contains more than 3900 constituents. In this presentation we have summarized our present knowledge as to the physicochemical nature of tobacco smoke and specific agents therein. Emphasis has been placed on the discussion of formation and identification of toxic and, especially, of tumorigenic agents in tobacco smoke. In the concluding Table 13 we have listed those smoke constituents in the mainstream smoke of cigarettes that we regard as important contributors to the toxic and carcinogenic potential of tobacco smoke. This judgement is based on extensive laboratory studies. Finally, data are presented in support of the concept that product modification can reduce the carcinogenic potential of cigarettes. However, it must be emphasized that the only safe way to avoid the cancer risks associated with smoking is to refrain from smoking.