Blood Lead Levels and Cause-Specific Mortality of Inorganic Lead-Exposed Workers in South Korea

The objective of this study was to identify the association of blood lead level (BLL) with mortality in inorganic lead-exposed workers of South Korea. A cohort was compiled comprising 81,067 inorganic lead exposed workers working between January 1, 2000, and December 31, 2004. This cohort was merged with the Korean National Statistical Office to follow-up for mortality between 2000 and 2008. After adjusting for age and other carcinogenic metal exposure, all-cause mortality (Relative risk [RR] 1.36, 95% confidence interval [CI] 1.03-1.79), digestive disease (RR 3.23, 95% CI 1.33-7.86), and intentional self-harm (RR 2.92, 95% CI 1.07-7.81) were statistically significantly higher in males with BLL >20 mu g/dl than of those with BLL <= 10 mu g/dl. The RR of males with BLL of 10-20 mu g/dl was statistically higher than of those with BLL <= 10 mu g/dl in infection (RR 3.73. 95% CI, 1.06-13.06). The RRs of females with 10-20 mu g/dl BLL was statistically significantly greater than those with BLL <10 mu g/dl in all-cause mortality (RR 1.93, 95% CI 1.16-3.20) and colon and rectal cancer (RR 13.42, 95% CI 1.21-149.4). The RRs of females with BLL 10-20 mu g/dl (RR 10.45, 95% CI 1.74-62.93) and BLL >= 20 mu g/dl (RR 12.68, 95% CI 1.69-147.86) was statistically significantly increased in bronchus and lung cancer. The increased suicide of males with >= 20 mu g/dl BLLs, which might be caused by major depression, might be associated with higher lead exposure. Also, increased bronchus and lung cancer mortality in female workers with higher BLL might be related to lead exposure considering low smoking rate in females. The kinds of BLL-associated mortality differed by gender.