Lung cancer mortality at a UK tin smelter

Background An earlier study of mortality among male former employees at a tin smelter in Humberside, UK, had identified excess mortality from lung cancer, which appeared to be associated with occupational exposure Aims The aim of the present study was to investigate the relationship between lung cancer mortality and quantitative measures of exposure. Methods Using available records of occupational hygiene measurements, we established exposure matrices for arsenic, cadmium, lead, antimony and polonium-210 (Po-210), covering the main process areas of the smelter. We established work histories from personnel record cards for the previously defined cohort of 1462 male employees. Three different methods of extrapolation were used to assess exposures prior to 1972, when no measurement results were available. Lung cancer mortality was examined in relation to cumulative inhalation exposure by Poisson regression analysis. Results No significant associations could be found between lung cancer mortality and simple cumulative exposure to any of the substances studied. When cumulative exposures were weighted according to time since exposure and attained age, significant associations were found between lung cancer mortality and exposures to arsenic, lead and antimony. Conclusions The excess of lung cancer mortality in the cohort can most plausibly be explained if arsenic is the principal occupational carcinogen (for which the excess relative risk diminishes with time since exposure and attained age) and if there is a contribution to excess mortality from an enhanced prevalence of smoking within the cohort. The implications of the dose-response for arsenic exposure for risk estimation merit further consideration.