Cancer and noncancer mortality among aluminum smelting workers in Badin, North Carolina

Background Badin, North Carolina, hosted an aluminum smelting plant from 1917 to 2007. The Concerned Citizens of West Badin reported suspected excess cancer mortality among former employees. This study aimed to investigate these concerns. Methods The study cohort was enumerated from United Steel Workers' records of workers employed from 1980 to 2007. Cause-specific mortality rates in the cohort were compared with North Carolina population mortality rates using standardized mortality ratios (SMRs), standardized by age, sex, race, and calendar period. We estimated cause-specific adjusted standardized mortality ratios (aSMRs) using negative controls to mitigate healthy worker survivor bias (HWSB). Standardized rate ratios (SRRs) were calculated to compare mortality rates between workers ever employed vs never employed in the pot room. Results All-cause mortality among Badin workers was lower than in the general population (SMR: 0.81, 95% confidence interval [CI]: 0.71-0.92). After adjusting for HWSB, excesses for all cancers (aSMR: 1.55, 95% CI: 1.10-2.21), bladder cancer (3.47, 95% CI: 1.25-9.62), mesothelioma (17.33, 95% CI: 5.40-55.59), and respiratory cancer (1.24, 95% CI: 0.77-1.99) were observed. Black males worked the highest proportion of their employed years in the pot room. Potroom workers experienced higher respiratory cancer (SRR: 2.99, 95% CI: 1.23-7.26), bladder cancer (SRR: 1.58, 95% CI: 0.15-15.28), and mesothelioma (SRR: 3.36, 95% CI: 0.21-53.78) mortality rates than never workers in the pot room. Conclusions This study responds to concerns of a group of former aluminum workers. The results, while imprecise, suggest excess respiratory and bladder cancers among pot room workers in a contemporary cohort of union employees at a US smelter.