Cancer mortality among female and male workers occupationally exposed to inorganic lead in the printing industry

Objective Evaluation of the carcinogenicity of lead for humans has been based primarily on the results of studies on occupationally exposed men, although gender differences in lead metabolism have been reported. In addition, most of the previous studies have been limited by a failure to identify and control for co-exposures to other known occupational carcinogens. The present study follows an industrial cohort of workers, mostly women, with moderate lead exposure and no confounding by other occupational exposures. Methods Workers, employed at least 2 years between 1950 and 1978 in manual and mechanical (linotype) typesetting and type foundries in 27 printing plants in Moscow, were included in the cohort, which comprised 1423 men and 3102 women. The cohort was followed up during 1979-2003 and contributed 93 682 person-years of observation. Follow-up was 97.7% complete. Standardised mortality ratios (SMRs) and 95% CIs, based on mortality rates of the Moscow general population and adjusted for gender, age and calendar time, were calculated for the total cohort as well as subcohorts stratified by various exposure parameters. Results Among women, mortality from all causes, circulatory diseases and all cancers combined was lower than that in the Moscow general population and was similar across work groups. Among men, there was excess overall mortality, mainly due to increased mortality from ischaemic heart disease. For both sexes, no significant excess risk for any cancer site was observed, although some dose-response patterns were found. In the overall cohort, mortality from cancers of the kidney and pancreas increased up to twofold in the highest tertile of cumulative lead exposure based on duration and a relative ranking of the three subcohorts (9 deaths; SMR=2.12, 95% CI 1.10 to 4.07) and (18 deaths; SMR=2.32, 95% CI 1.46 to 3.68), respectively. Similar mortality trends for these two cancers were found in analyses by gender. Conclusions Consistencies by sex and exposure level make a strong case for a link between exposure to inorganic lead and cancers of the kidney and pancreas.