Categorization of Associations Between Exposure to the Herbicides Used in Vietnam or Their Contaminants and Health Outcomes

Between 1962 and 1971, United States military forces sprayed herbicides over Vietnam. Because of ongoing uncertainty about the long-term health effects on Vietnam veterans of the herbicides sprayed, Congress passed the Agent Orange Act of 1991. That legislation directed the Secretary of Veterans Affairs to request the National Academy of Sciences, a non-profit organization that provides independent, objective advice on scientific issues, to perform a comprehensive review and evaluation of scientific and medical information regarding the health effects of exposure to Agent Orange, other herbicides used in Vietnam, and the various chemical components of those herbicides, including dioxin. The first comprehensive review was published in 1994 and biennial updates have integrated all subsequent and relevant peer-reviewed information. In assessing the evidence for an association of exposure to the herbicides or their components with a health outcome, the committee responsible for the report reviews the available literature and categorize the evidence as 1) sufficient for an association; 2) suggestive of an association; 3) inadequate or insufficient to determine whether an association exists; or 4) suggestive of NO association. Conclusions regarding the biological plausibility of the health effects and the risk to Vietnam veterans are also made. The latest reports, Veterans and Agent Orange: Update 2006, was released in March 2007. The assessments in the reports are used by the Department of Veterans Affairs to make policy decisions regarding compensation to veterans for service-related illnesses.