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OCR for page 1
Characterizing Exposure of Veterans to
Agent Orange and Other Herbicides
Used in Vietnam
Interim Findings and Recommendations
INTRODUCTION AND BACKGROUND
From 1962 to 1971, US military forces sprayed more than 19 million
gallons of herbicides over Vietnam to strip the thick jungle canopy that
helped conceal opposition forces, to destroy crops that enemy forces might
depend on, and to clear tall grass and bushes from around the perimeters
of US base camps and outlying fire-support bases. Most large-scale spray-
ing operations were conducted from airplanes and helicopters, but herbi-
cides were also sprayed from boats and ground vehicles, and by soldiers
wearing back-mounted equipment. After a scientific report concluded
that a contaminant of one of the primary chemicals used in the herbicide
called Agent Orange could cause birth defects in laboratory animals, US
forces suspended use of the herbicide; they subsequently halted all herbi-
cide spraying in Vietnam in 1971.
In response to concerns about the possible health consequences of
wartime exposure to herbicides, Congress passed Public Law 102-4, the
Agent Orange Act of 1991.~ The legislation directed the Secretary of
Veterans Affairs to request that the National Academy of Sciences con-
duct a comprehensive review and evaluation of available scientific and
medical information regarding the health effects of exposure to Agent
Orange, other herbicides used in Vietnam, and their components, in-
Codified as 38 USC§1116.
1
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2 EXPOSURE OF VETERANS TO AGENT ORANGE AND OTHER HERBICIDES
eluding the contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin, informally
known as TCDD or dioxin. A committee convened by the Institute of
Medicine (IOM) of the National Academies conducted the review and in
1994 published a comprehensive report titled Veterans and Agent Orange:
Health Effects of Herbicides Used in Vietnam (IOM, 1994~.
The committee responsible for the 1994 report encountered a severe
lack of information about the exposures of individual Vietnam veterans
to herbicides and found that this lack of information had hampered previ-
ous attempts to study the effects of exposure to herbicides on the health of
Vietnam veterans. That committee felt, however, that it might be possible
to develop better methods of determining exposures of individual veter-
ans by drawing on historical reconstructions. The methods might take
into account such factors as troop movements, ground and perimeter
spraying, herbicide shipments to various military bases, the terrain and
foliage typical of the locations sprayed, the military missions of the troops
located there, and biochemical techniques for detecting low concentra-
tions of dioxin in the blood. If better models of exposure could be devel-
oped and validated, the committee believed, a number of important epi-
demiologic studies of exposure to herbicides and health outcomes might
become possible.
As part of the 1994 report, recommendations were offered concerning
the need for additional scientific studies to resolve areas of continuing
scientific uncertainty. Three of these recommendations addressed expo-
sure assessment studies of Vietnam veterans (IOM, 1994~:
· A nongovernmental organization with appropriate experience in
historical exposure reconstruction should be commissioned to develop
and test models of herbicide exposure for use in studies of Vietnam
veterans.
· The exposure reconstruction models developed according to [the
previous recommendation] should be evaluated by an independent, non-
governmental scientific panel established for this purpose.
· If the scientific panel proposed [above] determines that a valid
exposure reconstruction model is feasible, the Department of Veterans
Affairs and other government agencies should facilitate additional epide-
miologic studies of veterans.
In response to that report, the Department of Veterans Affairs (VA)
asked IOM to establish a committee to oversee the development and
evaluation of models of herbicide exposure for use in studies of Vietnam
veterans. That committee would develop and disseminate a request for
proposals (REP) consistent with the recommendations; evaluate the pro-
posals received in response to the REP and select one or more academic or
OCR for page 3
INTERIM FINDINGS AND RECOMMENDATIONS
3
other nongovernmental research groups to develop the exposure recon-
struction model; provide scientific and administrative oversight of the
work of the researchers; and evaluate the models developed by the re-
searchers in a report to VA, which would be published for a broader
audience.
The Committee on the Assessment of Wartime Exposure to Herbi-
cides in Vietnam was formed in 1996 to accomplish those 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 com-
prised a statement of work, criteria for selecting researchers, and an ap-
pendix providing background information for potential respondents-
was released to the public on March 18, 1997. It summarized the RFP's
intent as follows (IOM, 1997, p. 3~:
1. Develop and document a detailed methodology for retrospective-
ly characterizing the exposure of Vietnam veterans to the major herbi-
cides used by the military in Vietnam 2,4-D; 2,4,5-T; cacodylic acid;
and picloram 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 expo-
sures to each of these substances is not necessarily a requirement for a
successful proposal. The exposure methodology proposed must be ap-
plicable to specific types of epidemiological investigations that could be
conducted at a future date under a separate contract or subcontract.
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 epidemiological studies.
A formal, complete RFP, including the scientific input and contrac-
tual requirements, was developed and was issued on tune 30, 1997. It was
initially sent to individuals 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 vet-
eran health research and through contacts made at meetings and confer-
ences attended by committee members and staff.
Three proposals were submitted by the due date of September 4,
1997. Committee members evaluated the technical and scientific merit of
these proposals on the basis of the criteria set forth in the RFP. They
concluded unanimously that a proposal submitted by researchers at Co-
lumbia University's Mailman School of Public Health Jeanne Mager
OCR for page 4
4 EXPOSURE OF VETERANS TO AGENT ORANGE AND OTHER HERBICIDES
Stellman, PhD, Principal Investigator) merited funding. That conclusion
was transmitted to VA on February 24, 1998, and the National Academies
initiated a contract with the researchers using funds provided by VA.
The REP 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 en-
countered and corrective actions; pertinent data or other information in
sufficient detail to explain significant results achieved and any prelimi-
nary 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" (page 10~. Progress reports were pre-
sented in public meetings of the committee to disseminate the informa-
tion to a larger audience and facilitate interaction between the committee
and the researchers. The first of these took place in a November 6, 1998,
meeting of the committee. Communication was maintained between
meetings on a less formal basis.
Discussion between the researchers and the committee played an im-
portant role in the project. In addition to being an essential component of
the committee's oversight of the contractor's work, it allowed for the
work plan to be more easily refined as the project progressed and for the
researchers to obtain opinions on alternative means for addressing the
challenges and opportunities that presented themselves.
As of January 2003, nine 6-month reviews had been completed. A1-
though the Columbia University effort (as specified in the response to the
REP and modified in consultation with the committee) has not yet been
completed, the committee believes that sufficient progress has been made
to permit some judgments to be stated.
On the basis of the committee's review of the contractor's 6-month
update reports, presentations through month 54, and published and draft
papers prepared by the contractor, the committee has reached the follow-
. .. ..
ng imclmgs:
· 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) 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 epide-
miologic studies. Additional location data for troops not currently in-
Representative terms from entire chapter:
agent orange
