[Problem of cigarette smoking in the epidemiological studies of lung cancer risks among industrial populations].

The concept of the confounding factor is discussed in relation to epidemiological studies, in particular, cigarette smoking is presented as a possible confounding factor in the determination of lung cancer risk in the populations with occupational exposure to carcinogens in their everyday work. In the light of the results of own investigations of a cohort exposed to asbestos dust the confounding effect of smoking on risk of lung cancer risk in this cohort is evaluated.