| A retrospective mortality and cancer incidence study of former nuclear weapons assemblers from the Iowa Army Ammunitions Plant was conducted. This study examined whether or not workers at the plant exhibited higher rates of mortality or cancer as a result of their work-related activities. Potential exposures included radiation, beryllium, asbestos, and solvents. Cancer incidence was determined by calculating standardized incidence ratios (SIR) and using the Iowa population as reference. SIRs were calculated on 3,889 workers from1969-2005. Overall and cause-specific mortality was determined by calculating standardized mortality ratios (SMR) and using the U.S. and Iowa populations as reference. SMRs were calculated on 5,743 workers from 1947-2005. The SIR results showed that overall cancer incidence was lower than the Iowa population. Using the Iowa population as reference, the SMR analyses for men demonstrated excesses for all cancers (SMR 1.09, 95% CI 1.02-1.17), lung cancer (SMR 1.38, 95% CI 1.24-1.54), diseases of the respiratory system (SMR 1.15, 95% CI 1.03-1.46), mesothelioma (SMR 6.20, 95% 1.28-18.1), asbestosis (SMR 9.28, 95% CI 1.12-33.5) and COPD (SMR 1.27, 95% CI 1.10-1.46). Significantly lower SMRs were observed stomach cancer and ischemic heart disease. For women excesses were observed for all cancers (SMR 1.41, 95% CI 1.17-1.69), lung cancer (SMR 2.47, 95% CI 1.72-3.44), ischemic heart disease (SMR 1.32, 95% CI 1.09-1.58), respiratory diseases (SMR 1.59, 95% CI 1.14-2.16), and COPD (SMR 2.47, 95% CI 1.60-3.65). Using the U.S. population, men experienced lower overall mortality while women had significantly higher overall mortality. In conclusion, the SIR portion of the study showed overall lower cancer incidence for both men and women. This may be due to the Healthy Worker Effect and the limited dates of study. There are no cancer registry data before 1969 thus missing cancers with short induction periods. Workers may have also moved out of the Iowa and had a cancer diagnosis in another state. Compared to Iowa population, there was an excess of respiratory disease deaths and deaths from lung cancer in both men and women. Considering the significant respiratory exposures workers may have experienced, further study with a nested case-control design is suggested. |
