Introduction: in 1976, a major chemical accident occurred in Manfredonia (Apulia Region, Southern Italy) due to an explosion in the fertilizer area. More than 10 tons of arsenic were released into the atmosphere, contaminating the plant and the surrounding areas. At the end of the 90s, criminal proceedings were initiated and a cohort study was conducted within the trial.
Objectives: to update the vital status of workers enrolled within the trial; some relevant results are also given.
Methods: two different approaches were used to update the vital status depending on the residence of the individuals in the cohort. We computed cause-specific standardised mortality ratios (SMRs), stratified according to the type of employment (urea sector, caprolactam sector, and contract workers), with 95% confidence intervals (95%CI). For internal comparison purpose, Cox regression models were used and hazard ratios (HRs) were calculated, considering workers from the caprolactam area as a reference category.
Results: the cohort consisted of 1,467 workers; 114 were dead at the end of the previous follow-up. Among 728 workers residing in Manfredonia, we identified 619 people still alive and 93 deceased. Among 625 not-residents, 508 were alive and 93 deceased. For 285 cases out of 306, cause of death was ascertained. Contract workers show a statistically significant SMR for lung cancer (SMR: 1.26; 95%CI 1.05-1.54) and an increased risk for overall mortality (HR: 2.3; 95%CI 1.1-4.9). Workers residing in Manfredonia show a higher risk of lung cancer mortality in comparison to not-residents (HR: 2.3; 95%CI 1.1-4.9).
Conclusions: workers who were most exposed to arsenic during the site cleaning show an increased risk of overall mortality compared to the least exposed and an increased risk of lung cancer compared to the general population.