THE MORTALITY OF LEAD SMELTER WORKERS - AN UPDATE

Objectives. Mortality studies of lead workers have shown excesses of nonmalignant renal disease ana cerebrovascular disease. Animal studies and one human study have shown excess kidney cancer. We have updated a mortality study of male lead smelter workers (n = 1990). Methods. An analysis was conducted using standard life table techniques. The updated analysis added 11 years of follow-up and 363 new deaths. Results. The original study had found elevated but nonsignificant risks for kidney cancer, stroke, and nonmalignant renal disease, probably attributable to lead exposure. Deaths from accidents and nonmalignant respiratory disease were significantly elevated, but probably not as a result of lead exposure. In the updated study, no new deaths from nonmalignant renal disease occurred (9 observed, standardized mortality ratio = 1.21). Three more deaths from kidney cancer were observed, yielding a standardized mortality ratio of 1.93 (9 observed, 95% CI = 0.88, 3.67), which increased for those who had worked in areas with the highest lead exposure (8 observed, standardized mortality ratio = 2.39, 95% CI = 1.03, 4.71). Cerebrovascular disease remained elevated for those with more than 20 years of exposure (26 observed, standardized mortality ratio = 1.41, 95% CI = 0.92, 2.07). Conclusions. This cohort with high lead exposure showed a diminishing excess of death from nonmalignant renal disease, a continued excess from kidney cancer, and an excess of cerebrovascular disease only in those with longest exposure to lead.