Long-term effect of arsenic exposure: Results from an occupational cohort study

Background In 1976 in Manfredonia (Italy), arsenic was released into the atmosphere due to an accident in a petrochemical plant. We aimed to analyze the mortality of workers involved in the factory for the site cleaning activities. Methods The cohort consisted of 1467 workers grouped into contract, fertilizer, and plastic workers. The outcome of interest was mortality for specific causes. Standardized mortality ratios (SMR) and 95% confidence intervals (95%CI) were computed. Results For all workers and all causes of death combined, the SMR was less than 1.0. Mortality ratios were increased for malignant neoplasms of the pleura, bone and melanoma of the skin. Contract workers, the group mostly exposed to arsenic, showed statistically significant SMRs for several malignancies, in particular for lung cancer (SMR = 1.26; 95%CI: 1.05-1.54). Conclusions Overall, the results reported here on mortality among persons occupationally exposed to arsenic are consistent with the literature and biologically plausible.