Mortality in a historical cohort of bus drivers

In an attempt to address previously reported excesses of ischaemic heart disease (IHD), lung cancer and bladder cancer among professional drivers, the mortality (SMR) of 2134 Montreal city bus drivers employed for at least five years as of January 1962 and followed until 31 December 1985 was compared with that of the male population of greater Montreal. The vital status of 94% of the cohort was ascertained. The number of deaths observed was 804. The overall mortality was somewhat lower than expected (SMR = 97). A small, non-significant excess mortality was found for ischaemic heart disease (IHD) (O/E = 313/295, SMR = 106, 95% CI: 95-118) and circulatory system diseases (O/E = 441/405, SMR = 109, 95% CI: 99-119). However, no excesses were observed for lung cancer (O/E = 78/84.4, SMR = 92, 95% CI: 73-114) or bladder cancer (O/E = 4/7.4, SMR = 54, 95% CI: 15-138). These results are compatible with other studies which have found a small risk of IHD for bus drivers.