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Jeanne Mager Stellman,¹ Steven D. Stellman,^2,3 Tracy Weber,¹ Carrie Tomasallo,¹ Andrew B. Stellman,⁴ and Richard Christian, Jr.⁵

¹Department of Health Policy and Management and ²Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York, USA; ³Institute for Cancer Prevention, Valhalla, New York, USA; ⁴Foundation for Worker, Veteran, and Environmental Health, Inc., Brooklyn, NY, USA; ⁵Lt. Col. U.S. Army (retired) and former Director U.S. Army and Joint Services Environmental Support Group, Washington DC, USA

Abstract

Between 1961 and 1971, U.S. military forces dispersed more than 19 million gallons of phenoxy and other herbicidal agents in the Republic of Vietnam, including more than 12 million gallons of dioxin-contaminated Agent Orange, yet only comparatively limited epidemiologic and environmental research has been carried out on the distribution and health effects of this contamination. As part of a response to a National Academy of Sciences' request for development of exposure methodologies for carrying out epidemiologic research, a conceptual framework for estimating exposure opportunity to herbicides and a geographic information system (GIS) have been developed. The GIS is based on a relational database system that integrates extensive data resources on dispersal of herbicides (e.g., HERBS records of Ranch Hand aircraft flight paths, gallonage, and chemical agent) , locations of military units and bases, dynamic movement of combat troops in Vietnam, and locations of civilian population centers. The GIS can provide a variety of proximity counts for exposure to 9,141 herbicide application missions. In addition, the GIS can be used to generate a quantitative exposure opportunity index that accounts for quantity of herbicide sprayed, distance, and environmental decay of a toxic factor such as dioxin, and is flexible enough to permit substitution of other mathematical exposure models by the user. The GIS thus provides a basis for estimation of herbicide exposure for use in large-scale epidemiologic studies. To facilitate widespread use of the GIS, a user-friendly software package was developed to permit researchers to assign exposure opportunity indexes to troops, locations, or individuals. Key words: Agent Orange, cacodylic acid, defoliants, 2, 4-dichlorophenoxy acetic acid, exposure opportunity, geographic information system, GIS, herbicides, military, picloram, 2, 4, 5-trichlorophenoxy acetic acid, Vietnam. Environ Health Perspect 111:321-328 (2003) .