In a study of 135 036 male Swedish construction workers aged 35 to 54 years, the relative risk of dying of cardiovascular causes was 1.4 times higher (95% CI, 1.2-1.6) in smokeless tobacco users than in nonusers.28 These results were adjusted for body mass index, age, diabetes, blood pressure, and a history of heart symptoms. However, some of the well-known risk factors, including hypercholesterolemia, were not included. A single-encounter questionnaire administered to these individuals between 1971 and 1974 was used to categorize subjects into smokers, ex-smokers, smokeless tobacco users, and nonusers. No follow-up results of the subjects' tobacco habits were available for any crossover after this questionnaire. The mortality data from the Swedish National Cause of Death Register were studied in 1984. Therefore, it is possible that some of the smokeless tobacco users may have shifted to smoking and hence falsely increased their relative risk in this study. The issue of whether these results can be extrapolated to the general population is also controversial. It has been argued that the nonusers in this study represented "healthier" construction workers, whose incidence of death as a result of cardiovascular causes was lower than that of the general population.