Cancer incidence, mortality, and blood lead levels among workers exposed to inorganic lead

Abstract

<h4>Purpose</h4>We aimed to measure mortality and cancer incidence in a cohort of lead-exposed workers by using blood lead levels to assess exposure.<h4>Methods</h4>The cohort comprised male lead workers. Subjects were matched to cancer and death registries. Observed death and cancer incidence rates were compared with population rates to obtain standardized mortality ratios (SMR) and standardized incidence ratios (SIR).<h4>Results</h4>There were 4114 male subjects with average follow-up time of 16.2 years, and 406 deaths were observed. There were significant results for overall death (SMR, 111; 95% confidence interval [95% CI], 101-123), digestive system deaths (SMR, 167; 95% CI, 110-250), and deaths from external causes (SMR, 135; 95% CI, 105-174). A total of 228 subjects had cancer, with an overall SIR of 83 (95% CI, 73-95); liver cancer SIR of 217 (95% CI, 103-454) and esophageal cancer SIR of 240 (95% CI, 129-447). The latter was seven-fold greater (SIR 755; 95% CI, 314-1813) among those with a blood lead level result above 30 μg/dL compared with population rates. No other increases in cancers were observed.<h4>Conclusions</h4>Overall mortality was elevated. Although incidence rates of overall cancer were low, further studies and analysis are required to investigate any biologically plausible associations between inorganic lead and liver or esophageal cancer.