From 1962 to 1971, US military sprayed herbicides over Vietnam to strip the thick jungle canopy that could conceal opposition forces, to destroy crops that those forces might depend on, and to clear tall grasses and bushes from the perimeters of US base camps and outlying fire-support bases.
Because of continuing uncertainty about the long-term health effects of the sprayed herbicides on Vietnam veterans, Congress passed the Agent Orange Act of 1991. The legislation directed the Secretary of Veterans Affairs to request the Institute of Medicine of the National Academy of Sciences (NAS) to perform a comprehensive evaluation of scientific and medical information regarding the health effects of exposure to Agent Orange and other herbicides used in Vietnam. Mandated updates to the original study were to be conducted every 2 years for 10 years. Veterans and Agent Orange, Update 2006 is the seventh report in this series.
The Update 2006 committee weighed the strengths and limitations of the epidemiologic evidence reviewed in this report and in previous Veterans and Agent Orange (VAO) reports. Although the studies published since Update 2004 are the subject of detailed evaluation in this report, the committee drew its conclusions in the context of the entire body of literature.
The committee assigns each health outcome to one of four categories on the basis of evidence. In this update, the committee reassigned several health outcomes from Update 2004. The committee added AL amyloidosis and hypertension to the list of conditions with limited or suggestive evidence of association with exposure to the herbicides sprayed in Vietnam. For the first time, a VAO committee found itself deadlocked on several of the health outcomes, and were unable to come to a consensus on their categorization. As a result, the health outcomes were left in the category of inadequate or insufficient evidence of an association.