Non-smoker lung cancer deaths attributable to exposure to spouse's environmental tobacco smoke. 
The causal relationship between environmental tobacco smoke (ETS) and lung cancer is established; however, the magnitude of the risk is not known.  Therefore, it is conceivable that ETS is responsible for a number of lung cancer deaths because of the large number of smokers and the widespread presence of ETS.  We estimated the number of lung cancer deaths occurring in 1990 in the European Union (EU), attributable to ETS generated by a spouse.  In each country and for each sex, we used the proportion of smokers and of married people in 1970 to estimate the number of lung cancer deaths not attributable to tobacco smoking occurring in married people, assuming a relative risk (RR) for active smoking equal to 10.  We then assumed a prevalence of smoking among these deaths equal to the population at large, and estimated the number of deaths attributable to ETS based on an RR for ETS of 1.3.  Additional analyses were carried out assuming different values of RR for smoking and exposure to spouse's ETS.  Based on our best assumptions, we calculated that 1146 (839 females, 307 males) lung cancer deaths were attributable to exposure to spouse's ETS in the EU in 1990.  All the hypotheses tested resulted in not less than several hundred deaths.  Regardless of the limitations of this exercise, our results suggest that exposure to spouse's ETS represents a relatively important public health problem in the EU.