Characterizing Exposure of Veterans to Agent Orange and Other Herbicides Used in Vietnam: Final Report (2003)

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INTRODUCTION AND BACKGROUND 3 proposals (RFP) consistent with the recommendations, evaluate the proposals received in response to the RFP and select one or more academic or other nongovernment research groups to develop the exposure-reconstruction model, provide scientific and administrative oversight of the work of the researchers, and evaluate the models developed by the researchers in a report to VA, which would be published for a broader audience. CONDUCT OF THE STUDY The Committee on the Assessment of Wartime Exposure to Herbicides in Vietnam was formed in 1996 to accomplish the model-development tasks. Its initial work resulted in the report Scientific Considerations Regarding a Request for Proposals for Research Characterizing Exposure of Veterans to Agent Orange and Other Herbicides Used in Vietnam (IOM, 1997). The report—which comprised a statement of work, criteria for selecting researchers, and an appendix providing background information for potential respondents—was released to the public on March 18, 1997. It summarized the intent of the research as follows (IOM, 1997, p. 3): 1. Develop and document a detailed methodology for retrospectively characterizing the exposure of Vietnam veterans to the major herbicides used by the military in Vietnam— 2,4-D; 2,4,5-T; cacodylic acid; and picloram3—and the trace contaminants TCDD and its congeners. The proposal should address how exposure to this array of chemicals will be evaluated. However, the ability to separately identify or quantify exposures to each of these substances is not necessarily a requirement for a successful proposal. The exposure methodology proposed must be applicable to specific types of epidemiologic investigations that could be conducted at a future date under a separate contract or subcontract. 3 These four herbicides were used individually and in combination as the active ingredients of the “Agent” formulations employed during the war: Agents Orange, Orange II, White, Blue, Pink, Purple, and Green. 

INTRODUCTION AND BACKGROUND 4 2. Demonstrate the feasibility and appropriateness of the proposed methodology in sufficient detail to permit the assessment of its potential for use in the conduct of epidemiologic studies. A formal, complete RFP, including the scientific input and contractual requirements, was developed and was issued on June 30, 1997. It was initially sent to persons and organizations that had requested it or were thought to have an interest in exposure-characterization research. Availability of the RFP was publicized on the Web sites of IOM's Board on Health Promotion and Disease Prevention and the Society for Risk Analysis and was posted to relevant e-mail lists. Members of the veteran community and other interested persons were also informed of the RFP through public events held by IOM committees involved in Vietnam-veteran health research and through contacts made at meetings and conferences attended by committee members and staff. Three proposals were submitted by the due date of September 4, 1997. Committee members evaluated their technical and scientific merit on the basis of the criteria set forth in the RFP. They concluded unanimously that a proposal submitted by researchers at Columbia University's Mailman School of Public Health (Jeanne Mager Stellman, PhD, principal investigator) merited funding. The terms of the contract specified that the researchers were to submit scientific progress reports every 6 months over the length of the contract. The progress reports were to include “a description of the overall progress; descriptions of the specific work accomplished, including problems encountered and corrective actions; pertinent data or other information in sufficient detail to explain significant results achieved and any preliminary conclusions resulting from analysis and scientific evaluation of data accumulated to date; and a description of the work to be accomplished over the following six months.” Progress reports were presented in public meetings of the committee to disseminate the information to a larger audience and facilitate interaction between the committee and the researchers. The first took place in a November 6, 1998, meeting of the committee, and the last occurred on January 13, 2003. Communication between the Columbia University researchers and the committee was maintained between meetings on a less formal basis. 

INTRODUCTION AND BACKGROUND 5 In April 2003, the committee issued an interim report based on the work that had been completed (IOM, 2003). On the basis of a review of the contractor's 6-month update reports and presentations and its published and draft papers, the committee reached the following findings: • The contractor has developed databases of wartime spraying and accidental dispersion of herbicides, of troop locations and movements, and of land features and soil typology. • The contractor has developed an effective exposure assessment tool to assign a metric—the E4 Exposure Opportunity Index (EOI)4—for herbicide exposure that is based on proximity to spraying in space and time and on the amount and agent sprayed. • The range of calculated EOIs and information gathered to date on troop locations is sufficient to demonstrate the feasibility of future epidemiologic studies. Additional location data for troops not currently included in present databases appear to be available at the National Archives5 for abstraction and use by researchers and other interested parties in future studies. • Given current knowledge and available data, the contractor has adequately demonstrated that the draft model is a valid means of assessing wartime herbicide exposure of Vietnam veterans. Given those findings, the committee concluded that a valid exposure-reconstruction model for wartime herbicide exposures of US veterans of Vietnam was feasible. It therefore recommended that the VA and other government agencies facilitate additional epidemiologic studies of veterans by nongovernment organizations and independent researchers. The intent of the present report is to summarize briefly the work done by the contractor over the life of the study and to serve as a vehicle for cataloging and transmitting that work to VA. The sections below delineate the work of the Columbia University researchers as it evolved from proposal through delivery. It is based on the material provided by the Columbia University 4 The EOI is not intended for use in evaluating the exposure of groups who were responsible for applying herbicides, although some of the information collected in the research effort may be useful in studies of these groups. 5 Formally, the US National Archives and Records Administration (NARA). 

INTRODUCTION AND BACKGROUND 6 researchers in their 6-month progress reports, presentations, draft materials, and final report; and it quotes freely and extensively from these materials. A complete list of the materials produced by the contractor in the course of its work is given in Appendix A; these materials are the definitive references for the research summarized here. The committee concludes here, on the basis of its review of the contractor's final report and all previous work, that the Columbia University researchers have satisfactorily completed the research project as defined in their proposal and modified in consultation with the committee. It also affirms all the findings and conclusions reached in its own Interim Report (IOM, 2003). The Interim Report details the reasoning that underlies the committee's conclusions regarding the scientific quality of the contractor's work. As detailed in that earlier report, a central issue was the demonstration that the draft model was a valid means of assessing the wartime herbicide exposure of Vietnam veterans. The Columbia University researchers implemented extensive quality control measures to assure the precision and completeness of their data, and offered both qualitative and quantitative validation information for their model. Considered together, this material led the committee to conclude that the exposure assessment model was feasible. The committee also notes that the Columbia University researchers' work has been subjected to additional peer review as part of the processes that lead to the papers they have published in Environmental Health Perspectives (Stellman JM et al., 2003) and Nature (Stellman SD et al., 2003) and that they will soon publish in Journal of Clinical and Consulting Psychology and Journal of Exposure Analysis and Environmental Epidemiology. Appendix A of this report notes other papers that are presently under preparation and submission.