A poisoned land: The legacy of Agent Orange in Vietnam

From 1961-1971, the United States military used aerial spraying to defoliate large swaths of Vietnam.   The defoliants, Agent Purple and Agent Orange, were contaminated with 2,3,7,8 tetrachlorodibenzodioxin (TCDD) with an estimated 165 – 366 kg being released over the country’s south in almost 20,000 spraying sorties. Estimates suggest that millions of Vietnamese were directly exposed during spraying.  In addition, defoliant handling created over two dozen TCDD hot spots with the largest being at the former US airbases in Da Nang, Bien Hoa, and Phu Cat.  The larger sites have been at least partially remediated but the majority remain contaminated and potential sources of TCDD.  TCDD, the most toxic member of the dioxin family, is remarkably resistant to degradation in ecosystems. TCDD bioaccumulates in the food chain rendering nutritious foodstuffs such as meats and milk a source of dietary exposure years after the original release of the herbicide. TCDD is a carcinogen and a developmental toxicant producing malformations and affecting endocrine, immune, nervous and reproductive systems.  New evidence suggests that TCDD operates through epigenetic mechanisms that are intergenerational (exposing germ cells of the fetus) and possibly transgenerational (transmitted through the germ line without direct exposure). These observations indicate that the Vietnamese populace has been adversely affected by dioxins and there is reason to suspect that the health effects continue to this day.  We call upon the US government to support the mitigation of hotspots and provide medical support comparable to that provided to US veterans.