[Occupational epidemiology: from analysis of the apparent to investigation of the unknown].

This paper, as a contribution for the centenary celebration of the establishment of the "Clinica del Lavoro Luigi Devoto" in Milan (Italy), presents a brief 30 year history of the activities of its Department of Occupational Epidemiology. Studies and methodological contributions that characterized the first decade of activity are presented and grouped under the heading of analysis of known health effects. The second decade was dominated by the studies and activities that originated from the Seveso accident (dioxin), with an initial interest towards molecular epidemiology, which became increasingly relevant during the third decade when we addressed topics like melanoma, lung cancer, and benzene, in addition to dioxin. More traditional occupational approaches were not dismissed and cohort mortality studies are currently under way (textile dyeing and finishing industry, sulfuric acid, tetrafluoroethylene). Pros and cons of the epidemiologic approach are discussed in the context of occupational health and the strength of its methodological apparatus is suggested as a fundamental tool for studying adverse occupational health effects. In contrast, it is stressed how occupational epidemiology has been poorly used in the application of law 626/94. Considering that contemporary epidemiology is much more inclined towards the discovery of new work-related risks (electromagnetic fields, air pollution) than the description of known health effects, the paper suggests that occupational epidemiology enlarge its interests: people and environment outside the factories might be good candidates for study.