During October 18-30, 1981, the second course of the International School of Pure and Applied Biostructure, a NATO Advanced Study Institute, was held at the Ettore Majorana Center for Scientific Culture in Erice, Italy, co-sponsored by the International Union Against Cancer, the Italian League Against Cancer, the Italian Ministry of Public Education, the Italian Ministry of Scientific and Technological Research, the North Atlantic Treaty Organization, the Italian National Research Council, the Sicilian Regional Government and two pharmaceutical Companies (Zambeletti and Farmitalia). The subject of the course was "Chemical Carcino genesis" with participants selected world-wide from 18 different countries. It is now eminently clear that.the bulk of human cancers are related to one of several types of environmental exposure. Of the environmental hazards, chemicals are among the best characterized carcinogens. However, how chemicals induce cancer is still poorly understood. Because of the magnitude of the problem and the ob vious need for a much more critical scientific analysis of the process by which cancer is induced (carcinogenesis), it was highly desirable to expose a greater number of scientists with varying background to some of the latest thinking in chemical carcino genesis. The course had this as its major objective and the re sulting book does reflect it.

This report considers the biological and behavioral mechanisms that may underlie the pathogenicity of tobacco smoke. Many Surgeon General's reports have considered research findings on mechanisms in assessing the biological plausibility of associations observed in epidemiologic studies. Mechanisms of disease are important because they may provide plausibility, which is one of the guideline criteria for assessing evidence on causation. This report specifically reviews the evidence on the potential mechanisms by which smoking causes diseases and considers whether a mechanism is likely to be operative in the production of human disease by tobacco smoke. This evidence is relevant to understanding how smoking causes disease, to identifying those who may be particularly susceptible, and to assessing the potential risks of tobacco products.