Click for next page ( 8


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 7
Characterizing Exposure ... Final Report CONTRACT SUMMARY The overall goal of the Columbia University research effort was to determine whether a valid and useful method could be developed for estimating Vietnam veterans' opportunity to be exposed to herbicides on the basis of historical reconstruction of relevant military records. The conceptual framework for the overall project included research on and quality control for the identification and reconstruction of military records, development and testing of exposure- opporiunity models that used those records, and research on selected Vietnam veterans to understand the extent to which covariates or confounders need to be taken into account in epidemiologic studies of the health effects of herbicides on Vietnam veterans. The goal was to elucidate the basic determinants of exposure: person, place, and time. With regard to person, the aim was to identify the specific locations of a veteran's military units and the specific tasks that may have resulted in exposure to herbicides. The Columbia University researchers were also interested in elucidating in-service and post-service experiences that might have affected any potential response to herbicide exposure so that they could be controlled for in future epidemiologic studies. They aimed to determine the extent to which the long period since the end of the spraying activities could affect a veteran's recall and the researchers' ability to identify and locate potential epidemiologic cohort members.7 With respect to place and time, the researchers' goals were to optimize the quality of the data available on herbicide spraying and to develop statistically robust models for herbicide-exposure opportunity for the entire period of the Vietnam War. Another research aim was to provide guidance for future epidemiologic studies on the degree to which important confounders and covariates might influence the outcome of epidemiologic health studies with respect to herbicide exposures. On the basis of previous studies of veterans' 6 Several terms are used to specify the organizational position and size of a military unit. The primary terms used in the US Army during the war were corps, division, brigade, battalion, company, platoon and squadron. Other services used different designations. 7 All protocols involving human subjects were submitted to the Columbia University Institutional Review Board and were approved. They included procedures and systems for preventing records access by persons who were not members of the study team. 7

OCR for page 7
Characterizing Exposure ... Final Report health, including their own published work (StelIman SD et al., 198Sa, 198Sb; StelIman IM et al., 1988; Snow et al., 1988), the contractors hypothesized that the experience of combat might have a profound effect both on subsequent health and on such important lifestyle factors as smoking and drinking, which, in turn, heavily influence disease outcomes. They thus undertook a large-scale survey of veterans to gather and evaluate the association among demographic, socio-economic status and behavior variables; military service history; self-reported exposures to herbicides and to combat; measures of post-traumatic stress disorder (PTSD) and other psychiatric symptoms; and numerous health outcomes. A focused study of women veterans was also conducted and an outreach effort was conducted to involve black and Hispanic veterans in order to evaluate the generalizability of such measures. The working plan proposed by the contractor consisted of fives interrelated projects on various methodologic aspects of characterizing herbicide exposures of American troops who served in Vietnam. Each project was related to an aspect of the historical reconstruction of exposure to herbicides. The projects were as follows: Project ]: Military Unit and Herbicide Spraying Databases, and Exposure Assessment Mode! Development Compilation and assessment of data on troop locations. Collection of data on the application of herbicides in the wartime aerial spraying program and other releases such as perimeter spraying. Analysis of the database contents to evaluate their suitability for use in the historical reconstruction of exposure to herbicides. Development and refinement of a means of characterizing wartime exposure of US veterans to herbicides. A sixth proposed project would have developed priorities and methods for epidemiologic research based on the findings of Projects 1-5, other available health-outcome databases, and additional technical and pragmatic considerations. This project was not included in the final contract, because a decision was made to focus on activities related to the development of an exposure-assessment model. 8

OCR for page 7
Characterizing Exposure ... Final Report Creation of a user-friendly software system to facilitate the estimation of exposure. Project 2: Covariates, Confounders, and Consistency: Characterizing the Vietnam Veteran for Epidemiologic Studies Examination of self-reports of military service, exposure to herbicides, and confounders and covariates of methoclologic interest (such as combat experience). Evaluation of validity of veteran recall and various approaches to obtaining self-reportec3 data. Project 3: Evaluation and Standardization of Military Records for Use in Epidemiologic Studies9 Certification of the Vietnam-era military personnel ant! other records that contain information potential relevant to epiclemiologic studies. Development and testing of a standardized means to abstract records data needler! to determine a veteran's ciates of service in-country, military unites), occupationts), and other service-relatecl information potentially relevant to epidemiologic studies. Evaluation of the consistency of the records data with self-reports of military service and experience. Development of a guide to obtaining and abstracting military records for use in epidemiologic research. Project 4: Biomarkers of TCDD (DioxinJ Exposure in Vietnam Veterans 9 This project was entitled Evaluation and Standardization of Military Personnel Records for Epidemiologic Studies in the contractor's proposal. It is revised here to clarify that both personnel and other records were examined. 9

OCR for page 7
Characterizing Exposure ... Final Report . Evaluation of TCDD in blood serum samples from selected veterans likely to have been heavily exposed and of an appropriate selection of Vietnam-era veteran controls using high- resolution gas chromatography/high-resolution mass spectrometry analysis. Examination of the utility of chemical-activated luciferase gene expression (CALUX) analysis as a lower-cost method of screening for TCDD exposure in studies of Vietnam veterans. Project 5: Analysis of International Agency for Research on Cancer (lARC) Tissue Samples of Selected Vietnamese for Dioxin and Dibenzofuran Levels in Archived Adipose Tissues Evaluation of the correlation between levels of TCDD and dioxin- and dibenzofuran congeners in adipose tissue collected *om Vietnamese citizens as part of an lARC case- contro! study tissue archive with lifetime residence-history data and herbicide-spray records, on the basis of the exposure-opportunity index developed in Project ~ . Evolution of Project Development and Implementation In the course of the study, the Columbia University researchers entered considerable amounts of data into new composite databases, creating, cleaning, and expanding archives for use in future epidemiologic studies. They also refined their computational approaches and developed new approaches to classifying and analyzing existing data. The researchers conducted two large surveys to elucidate the extent to which covariates and confounders must be considered in designing and executing studies of the effects of herbicide exposure on Vietnam veterans. In the course of seeking access to military personnel records for research purposes, they documented gaps and flaws in the data and identified potential barriers to conducting new studies of veterans' health. 10