[The tobacco-cancer problem]

Statistical, biological and chemical data on the carcinogenic effect of tobacco smoke are given and are discussed. The epidemiological studies have clearly shown the particularly noxious action of inhalation, and the direct ratio between the risk and the number of cigarettes smoked. The laboratory experiments on biological properties of cigarette smoke raise various problems of interpretation, however they reinforce the results given by statistical studies on man. The quantities of carcinogenic compounds which have been isolated from cigarette smoke are too small to account for the whole action. The co-carcinogenic, promoting, necrosing and toxic effects of some smoke condensate fractions could play an important part in the carcinogenic action. To cope with the health problems of the smoking habit, the tobaccoproducers and the public health organisations have taken steps, which led to a better knowledge of the problem and to the production of cigarettes which are less harmful to man.