Epidemiological survey of maintenance workers in London Transport Executive bus garages and Chiswick Works.

A mortality study of maintenance men employed for at least one year between 1 January 1967 and 31 December 1975 at 71 London Transport bus garages and Chiswick Works has been carried out. Over 97% of the population were successfully traced to determine their vital status at 31 December 1975. The mortality observed in the study population was compared with that which would be expected from the mortality rates for the all male population of England and Wales. The mortality of the study population from all causes was much lower than expected on this basis, as was the mortality from cerebrovascular disease, ischaemic heart disease, and bronchitis. Mortality from all neoplasms was slightly less than expected overall and especially in the younger age groups. The observed deaths from cancer of the lung were approximately the same as those expected on the basis of national rates. Nevertheless, a deficit of observed deaths from lung cancer was obtained after adjusting for the higher mortality from this disease in Greater London. Raised mortality was found in subgroups of the population for several malignant disease groups but these were almost all based on small numbers of deaths, making it difficult to exclude chance effects. Both the number of men and deaths in the study were limited and the follow up time was also short. Considerable extension of the study to include more men and increase the follow up time would be required for any definite mortality patterns to emerge.