ABSTRACT
A significant trend of increasing risk with presumed extent of passive exposure was present when either the husbands' lifetime smoking habits were used for stratification. Causal associations between active cigarette smoking and cancer of the lung and other sites have been long established on the basis of extensive sociological, experimental, and epidemiological evidence. Association between passive smoking and lung cancer derives biological plausibility from the chemical composition of sidestream smoke, the confirmation of exposure in nonsmokers with biological markers, and the failure to find a threshold for respiratory carcinogenesis in active smokers. The association between passive smoking and lung cancer has been approached with conventional hypothesis-testing designs: the case-control and cohort studies. Evidence concerning passive smoking and lung cancer has been sought indirectly in descriptive data and directly with case-control and cohort studies. Lung cancer risk increased with the spouses' lifetime cigarette consumption.
