A mortality study in two ammunition plants

Purpose of the study. To describe the mortality of workers employed in two ammunition plants and to compare it to the local population. Method. A cohort was set up of all male and female workers having worked for at least three successive months between 1st January 1974 and 31st December 2004. The cohort was followed up for mortality from 1st January 1974 to 31st December 2004. Vital status was assessed by searching in the national computerized database listing all deceased subjects in France, by contacting the registry office of the birthplaces for people born in France, and by contacting the registry office devoted to foreign-born French people. The causes of death were determined by matching with the French national database of causes of death. Standardized Mortality Ratios (SMR) were computed using local death rates. Mortality analysis was performed firstly among the entire cohort and secondly among blue-collar workers at the time of hiring. Results. The cohort included 1994 males and 696 females. The mortality for all causes was close to the local population's among males (258 deaths, SMR 1.02, CI95% 0.90-1.15) and lower than the local Population's among females (39 deaths, SMR 0.85, CI95% 0.62-1.16). Similar results were observed for all cancer mortality (88 deaths; SMR 0.98, CI95% 0.80-1.21 among males and 13 deaths; SMR 0.74, CI95% 0.39-1.27 among females). However, a significant mortality excess was observed among blue-collar workers (52 deaths, SMR 1.41, CI95% 1.08-1.85). This excess corresponded to cancers of the oral cavity, pharynx, larynx, oesophagus, stomach, and of the group trachea, bronchus, lung. However, it doesn't seem to be due to occupational activities in the plants. This excess of mortality from cancers decreased with duration of employment and is only statistically significant for workers having worked less than 10, years in the plants. Moreover, this excess was observed during the first years of employment and mainly among subjects hired after the age of 50. While we Cannot exclude an Occupational origin for this excess, it seems therefore plausible that this origin is prior to employment in the plants. However, the lack of information concerning job histories and occupational exposures before and during employment in the plants limit the interpretation of the results. Conclusion. This study showed mortality for all causes and for all cancers close to the local population's. The excess mortality from cancers observed among blue-collar workers doesn't seem to be due to occupational activities in the plants. (C) 2009 Elsevier Masson SAS. All rights reserved.