Health status of Army Chemical Corps Vietnam veterans who sprayed defoliant in Vietnam

Background U.S. Army Chemical Corps veterans handled and sprayed herbicides in Vietnam resulting in exposure to Agent Orange and its contaminant 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD or dioxin). This study examined the long-term health effects associated with herbicide exposure among these Vietnam veterans. Methods A health survey of these 1,499 Vietnam veterans and a group of 1,428 non-Vietnam veterans assigned to chemical operations jobs was conducted using a computer-assisted telephone interview (CATI) system. Exposure to herbicides was assessed by analyzing serum specimens from a sample of 897 veterans for dioxin. Logistic regression analyses were used to estimate the risk of selected medical outcomes associated with herbicide exposure. Results Odds ratios for diabetes, heart disease, hypertension, and chronic respiratory disease were elevated, but not significantly (P > 0.05) for those who served in Vietnam. However, they were significantly elevated among those Vietnam veterans who sprayed herbicides: diabetes, odds ratio (OR) = 1.50 (95% confidence interval [95%CI] = 1.15-1.95); heart disease, OR = 1.52 (1.18-1.94); hypertension, OR = 1.32 (1.08-1.61); and chronic respiratory condition, OR=1.62(1.28-2.05). Hepatitis was associated with Vietnam service, but not with herbicide application. Conclusions Vietnam veterans who were occupationally exposed to herbicide experienced a higher risk of several chronic medical conditions relative to other non-Vietnam veterans. A potential selection bias is of concern. However, there were relatively high participation rates in both the Vietnam and non-Vietnam veteran groups, and the prevalence rates of some of these medical conditions among non-Vietnam veterans were comparable to general populations. Therefore, self-selection factors are considered unlikely to have biased the study results.