Long-Term Health Effects of Vietnam War's Herbicide Exposure on the Vietnamese Population

Background: Long-term health effects of exposure to Agent Orange have been a subject of debate and controversy. Most studies on Agent Orange health effects were based on small samples. The objective of this population-based study is to determine whether Agent Orange exposure increases the risks of cancer and hypertension for the Vietnamese population. Methods: This study employs a quasi-experiment research design to estimate the causal long term effect of Agent Orange on incidences of cancer and hypertension for Vietnamese population. Specifically, difference-in-differences regressions are estimated which compute the difference between the Agent Orange-affected cohort versus the unaffected cohort in a treated area (where the Agent Orange was sprayed) and compare that difference with the similar difference computed for the control area (where the Agent Orange was not used). Results: People who were directly exposed to Agent Orange spraying have a higher risk of developing cancer. Agent Orange exposure appears to raise significantly the risk of hypertension for those who lived as well as those who were born during the spraying period. The most harmful effects of Agent Orange occur in areas that received the largest amounts of herbicide spray. Interpretation: The results provide statistical evidence for the harmful effects inflicted by herbicide exposure on the Vietnamese population. Our findings of elevated risk of cancer and hypertension complement the small-sample studies conducted for the Vietnam War veterans and raise warnings for the use of Agent Orange and other herbicides in populated areas.