Cancer mortality patterns in the lead industry.

The mortality of 7,032 men employed for one or more years in lead production facilities ("smelters") or battery plants was observed over a 23-year period, 1947-1970. There were 1,267 certified deaths. Lead absorption in many members of the cohort was known to have been greatly in excess of accepted standards. The standardized mortality ratio (SMR) for all causes was 107 for smelter workers and 99 for battery plant workers. Deaths from malignant neoplasms were somewhat elevated in both groups, the SMR being 133 for smelter workers and 111 for battery plants. The excesses arose largely from tumors of the digestive organs and the respiratory system. Only three deaths are attributed to malignant renal tumors and seven to tumors of the central nervous system. The latter findings were of interest in view of the experimental production of renal tumors in rats and mice by the injection or oral administration of very large doses of lead salts, and the report by one group of investigators of gliomas in rats fed lead subacetate. Studies are continuing to characterize more fully the exposure of the above lead workers to substances other than lead. Additional follow-up of the cohort is also contemplated.