ROUTES OF ASBESTOS EXPOSURE AND THE DEVELOPMENT OF MESOTHELIOMA IN ANENGLISH REGION

Objectives-To investigate the contribution of exposure to asbestos thr ough different routes in the development of mesothelioma. Methods-Case -control study. 185 confirmed cases of mesothelioma and 160 controls w ere identified, when death had occurred between 1979 and 1991 in four health districts in Yorkshire. The surviving relatives were interviewe d to ascertain lifetime exposure to asbestos. Adjusted odds ratios (OR s) of exposure to asbestos (through occupational, paraoccupational, an d residential routes) were calculated for cases and were compared with controls. Results-Likely or possible occupational exposure to asbesto s was more common in cases than in controls (OR 5.6, 95% confidence in terval (95% CI) 3.1 to 10.1). After excluding those with Likely or pos sible occupational exposure, likely or possible paraoccupational expos ure was more common in cases than controls (OR 5.8, 95% CI 1.8 to 19.2 ). Only six cases of mesothelioma were identified as being solely expo sed to asbestos through their residence, compared with nine controls. The OR for residential exposure to asbestos varied between 1.5 and 6.6 , depending on which potential industrial sources were included, but t he 95% CIs were so wide that slightly reduced or greatly increased odd s comparing cases with controls could not be excluded. Conclusion-Stud y results support previous evidence that occupational and paraoccupati onal exposure to asbestos is associated with developing mesothelioma. Despite a rigorous search, purely residential exposure seemed to accou nt for only 3% of identified cases. No firm conclusion can be drawn ab out the risks from residential exposure alone, as many of the study su bjects could also have been occupationally or paraoccupationally expos ed to asbestos.