Mortality Patterns of Army Chemical Corps Veterans Who were Occupationally Exposed to Herbicides in Vietnam

Abstract

This research examined the risk of disease-related mortality of the Army Chemical Corps (ACC) veterans who handled/sprayed herbicides in Vietnam in comparison with their non-Vietnam veteran peers or U.S. men. Vital status was determined through December 31, 2005. All-cause mortality and cause-specific mortality were compared for individuals who served in Vietnam (n = 2872) versus those who did not (n = 2737). Similar analyses were completed on a subset of the original Vietnam cohort that consisted of individuals who either reported spraying herbicide (n = 662) or not (n = 811). The observed deaths for each of the two base cohorts were also compared with expected deaths for U.S. men. Statistically significant excess mortality was found for ACC Vietnam veterans for chronic obstructive pulmonary disease (adjusted relative risk [ARR], 4.82; 95% confidence interval [95% CI], 1.10-21.18). When examining patterns for veterans in the Vietnam veteran subset, we found nonsignificant elevated ARRs among herbicide sprayers for all-cause, respiratory system disease, and respiratory system cancer mortality. Compared with U.S. men, the Vietnam veteran cohort had significant excess mortality for all-causes (standardized mortality ratio [SMR], 1.13; 95% CI, 1.04-1.23), respiratory system cancer (SMR, 1.35; 95% CI, 1.03-1.73), nonmalignant respiratory system disease (SMR, 1.58; 95% CI, 1.08-2.23), and miscellaneous malignant cancers (SMR, 1.77; 95% CI, 1.03-2.84). The risk of mortality from respiratory disease (malignant or nonmalignant) was significantly greater for ACC Vietnam veterans in comparison with their non-Vietnam veteran peers and U.S. men. Herbicide exposure could be contributing to the patterns observed. Because of the unique nature of their military duties and study limitations, findings may not be generalizeable to Vietnam veterans as a whole.