On July 6, 2005, the Department of Defense released the latest report
of the Air Force Health Study on the health effects of exposure to
herbicides in Vietnam, which includes the strongest evidence to date
that Agent Orange is associated with adult-onset diabetes. This
supports the findings from earlier reports in 1992 and 1997. Herbicide
Orange [a mixture of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-
trichlorophenoxy-acetic acid (2,4,5-T)] was used as a defoliant during
the Vietnam War. Other herbicides containing 2,4,5-T were also used
extensively; and as commonly used by the news media, the term
“Herbicide Orange” refers to all of these 2,4,5-T products. These
herbicides were contaminated with 2,3,7,8-tetrachlorodibenzo-p dioxin
(TCDD), and the presence of this toxin is the basis for much of the
concern over exposure to these defoliants. More than 3,000 veterans
have filed claims for compensation against the Veterans
Administration. In response to Congress, the General Accounting Office
investigated the issue and subsequently recommended that the
Department of Defense conduct a long-term epidemiologic study of the
problem. The Department of the Air Force has made a formal commitment
to the Congress and the White House to conduct such a study. On
September 16, 1980, the White House directed the Department of Defense
to initiate the Ranch Hand study with reasonable speed and high
quality. This decision was subsequently reaffirmed by the new
administration. The Air Force Health Study summarizes the results of
the 2002 physical examination of 1,951 veterans, which is the final
examination of the 20-year epidemiological study. The Ranch Hand Study
was named after the operation responsible for spraying herbicides in
Vietnam between 1962 and 1971 to deny cover and destroy crops of the
North Vietnamese Army. ince the first examination in 1982, the Air
Force has tried to determine hether long-term health effects exist in
the Ranch Hand pilots and ground crews, and if these effects can be
attributed to the herbicides used in Vietnam, mainly Agent Orange and
its contaminant, dioxin. The report, along with many other studies on
herbicide and dioxin exposure, will be reviewed by the National
Academy of Sciences. Based upon this review, the Secretary of Veterans
Affairs can ask Congress for legislation on disability compensation
and health care. Results from the 2002 physical examination support
adult-onset diabetes as the most important health problem seen in the
Air Force Health Study. They suggest that as dioxin levels increase,
not only are the presence and severity of adult-onset diabetes
increased, but the time to onset of the disease is decreased. A 166
percent increase in diabetes requiring insulin control was seen in
those with the highest levels of dioxin, consistent with the strong
evidence found in animal studies.