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U.S. Department of Health and Human Services

Advisory Committees

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Ranch Hand Advisory Committee - Summary of Findings

Having completed a thorough evaluation of the long-term effects of Agent Orange and other phenoxy herbicides to the satisfaction of the department of Health and Human Services and the National Center for Toxicological Research, the committee met for the final time on September 7, 2006.

In December 1979, the United States Air Force began investigating the possible long-term health effects of phenoxy herbicides (including Agent Orange) and contaminants (specifically dioxin) by conducting epidemiologic studies, known as the Ranch Hand Study, on U.S. Veterans who participated in the U.S. Army’s deployment of herbicides in Vietnam during “Operation Ranch Hand,” The conduct of the study was overseen by an independent monitoring committee, the Ranch Hand Advisory Committee (Committee). The Committee, established in 1981, was under the auspices of the Department of Health and Human Services, and was directed by the Food and Drug Administration’s National Center for Toxicological Research. It consisted of nine members, of which not less than one-third were selected by the Secretary of Health and Human Services from scientists recommended by U.S. Veterans organizations. Committee meetings were held approximately twice annually, from 1999 through 2006, and were open to the public except when directed by the Commissioner of the Food and Drug Administration.

This summary of the findings of the Ranch Hand Advisory Committee will focus on the most important adverse health effects that resulted from Operation Ranch Hand. Other adverse health effects, although significant, have been omitted from this summary for brevity, and can be found in the Committee’s public records online.

  • Studies pertaining to the effect of dioxin on the incidence and severity of cancer in Ranch Hand Veterans (RHVs) showed dioxin to be a risk factor for cancer. Moreover, higher dioxin levels were found in individuals who served earlier, rather than later in the war, confirming the suspicion that herbicides were more heavily contaminated earlier in the war. Overall, a significant association was found between cancer and years of service.
  • When determining the correlation between exposure to the herbicides and leukemia, the Committee found insufficient evidence to establish an association between the two.
  • Regarding neurobehavioral disorders, the committee found that Veterans exposed to both low and high levels of dioxin reported complaints of daytime fatigue, daytime sleepiness, and insomnia. Data collected in 1992 and again in 1997 indicate an increased incidence of peripheral neuropathy among RHVs exposed to higher dioxin levels. A study performed in 1982 also showed small deficits in immediate and delayed memory recall among RHVs, although a follow-up study in 2002 showed no memory function deterioration in RHVs relative to comparison veterans. The cause of the initial memory deficits is unknown.
  • Exploration of the other adverse health effects of herbicides included a mortality study conducted on RHVs through 2006 which found an increased risk of circulatory disease among RHVs (enlisted ground crew) in both high and low dioxin categories. Increased glucose intolerance and diabetes were also found among RHVs. Current analyses did not change the prevalence of diabetes, but showed a faster and stronger severity, onset, and relative risk of diabetes in RHVs with high dioxin levels.

If you have questions or comments about this advisory committee, please contact the Designated Federal Officer, Margaret A. Miller, Ph.D. at 301-827-6693 or Margaret.Miller@fda.hhs.gov.


Contact FDA

National Center for Toxicological Research

Food and Drug Administration

3900 NCTR Road

Jefferson, AR 72079