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The extent and patterns of usage of Agent Orange and other herbicides in Vietnam


Herbicides including Agent Orange were sprayed by United States forces for military purposes during the Vietnam War (1961–1971) at a rate more than an order of magnitude greater than for similar domestic weed control. In 1974, the US National Academy of Sciences published estimates of the extent and distribution of herbicides sprayed. Here we present revised estimates, developed using more-complete data. The spray inventory is expanded by more than seven million litres, in particular with heavily dioxin-contaminated herbicides. Estimates for the amount of dioxin sprayed are almost doubled. Hamlet census data reveal that millions of Vietnamese were likely to have been sprayed upon directly. Our identification of specific military herbicide targets has led to a more coherent understanding of spraying. Common errors in earlier interpretations of the spray data are also discussed.

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This research was supported by the National Academy of Sciences, the Department of Veterans Affairs and USPHS at the National Cancer Institute. We thank D. Hakenson and his staff at the US Armed Services Center for Research of Unit Records for technical support and access to military records; the staff of the National Archives and Records Administration, particularly R. Boylan and M. O. Adams; N. Heim for assistance with illustrations and F. Benjamin for assistance with military records. R.C. is a retired member of the US Army.

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Correspondence to Jeanne Mager Stellman.

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The authors declare that they have no competing financial interests.

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Further reading

Figure 1: Herbicide projects, targets and spraying19.
Figure 2: We could not locate target documentation for half the Ranch Hand missions on the HERBS file.
Figure 3: Volumes of herbicide sprayed.
Figure 4: Litres of herbicides sprayed over 1962–1971.
Figure 5: Time course of herbicide sorties.


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