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.