Agent Orange Exposure and Disease Prevalence in Korean Vietnam veterans

INTRODUCTION:  Between 1961 and 1971, tactical herbicides were used by US and allied forces in Vietnam for military purposes. Agent Orange, the most-used tactical herbicide, contained an impurity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most toxic dioxin congener. Many Korean Vietnam veterans were exposed to military herbicides including Agent Orange during the Vietnam War. The aim of this study was to evaluate the association between Agent Orange exposure and the prevalence of diseases of the endocrine, nervous, circulatory, respiratory, and digestive systems. 

METHODS:  The Agent Orange exposure index was based on the proximity of the veterans' military unit to the Agent Orange-sprayed area using a geographic information system-based model. A total of 111,726 Korean Vietnam veterans were analyzed for prevalence of various diseases from January 2000 to September 2005. Adjusted odds ratios and 95% confidence intervals were calculated using logistic regression models.

RESULTS:  The high exposure group had significantly elevated ORs for endocrine diseases combined and neurologic diseases combined. The ORs for specific diseases including but not limited to disorders of the thyroid gland such as non-iodine deficiency hypothyroidism and autoimmune thyroiditis, diabetes mellitus, other endocrine gland disorders including pituitary gland disorders, metabolic disorders such as lipidemia and amyloidosis, systemic atrophies including spinal muscular atrophy, Alzheimer disease, peripheral polyneuropathies, angina pectoris, stroke, chronic obstructive pulmonary diseases including chronic bronchitis and bronchiectasis, asthma, peptic ulcer, and liver cirrhosis, were higher in the high exposure group than in the low exposure group.

CONCLUSIONS:  Agent Orange exposure increased the prevalence of endocrine disorders, especially in the thyroid and pituitary gland; various neurologic diseases; COPD; and liver cirrhosis. Overall, this study suggests that Agent Orange/2,4-D/TCDD exposure several decades earlier may increase morbidity from various diseases. Further research is needed to better understand the long-term effects of Agent Orange/TCDD exposure on human health and their mechanisms.