Gulf War Illnesses: DOD's Conclusions About U.S. Troops' Exposure Cannot Be Adequately Supported
Published: 2004-06-01T00:00:00

Fast Facts:

Highlights:
section_title: Why GAO Did This Study
paragraphs: Since the end of the Gulf War in 1991, many of the approximately 700,000 U.S. veterans have experienced undiagnosed illnesses. They attribute these illnesses to exposure to chemical warfare (CW) agents in plumes--clouds released from bombing of Iraqi sites. But in 2000, the Department of Defense (DOD) estimated that of the 700,000 veterans, 101,752 troops were potentially exposed. GAO was asked to evaluate the validity of DOD, the Department of Veterans Affairs (VA), and British Ministry of Defense (MOD) conclusions about troops' exposure.
section_title: What GAO Found
paragraphs: DOD's and MOD's conclusion about troops' exposure to CW agents, based on DOD and CIA plume modeling, cannot be adequately supported. The models were not fully developed for analyzing long-range dispersion of CW agents as an environmental hazard. The modeling assumptions as to source term data--quantity and purity of the agent--were inaccurate because they were uncertain, incomplete, and nonvalidated. The plume heights used in the modeling were underestimated and so were the hazard area. Postwar field testing used to estimate the source term did not realistically simulate the actual conditions of bombings or demolitions. Finally, the results of all models--DOD and non-DOD models--showed wide divergences as to the plume size and path. DOD's and VA's conclusion about no association between exposure to CW agents and rates of hospitalization and mortality, based on two epidemiological studies conducted and funded by DOD and VA, also cannot be adequately supported because of study weaknesses. In both studies, flawed criteria--DOD's plume model and DOD's estimation of potentially exposed troops based on this model--were used to determine exposure. This may have resulted in large-scale misclassification. Troops under the path of the plume were classified as exposed; those not under the path, as nonexposed. But troops classified as not exposed under one DOD model could be classified as exposed under another DOD model. Under non-DOD models, however, a larger number of troops could be classified as exposed. Finally, as an outcome measure, hospitalization rate failed to capture the types of chronic illnesses that Gulf War veterans report but that typically do not lead to hospitalization.

section_title: Letter
paragraphs: We are pleased to participate in this international hearing by presenting  our assessment of the plume modeling, conducted by the Department of  Defense (DOD) and the Central Intelligence Agency (CIA), to determine  the number of U.S. troops that might have been exposed to the release of  chemical warfare agents during the Gulf War in 1990. We presented our  preliminary results to you in our testimony on June 2, 2003. My statement  today is based on our final report, entitled Gulf War Illnesses: DOD’s  Conclusions about U.S. Troops’ Exposure Are Unsupported, which is  being issued today.
As you know, many of the approximately 700,000 veterans of the Persian  Gulf War have experienced undiagnosed illnesses since the war’s end in  1991. Some fear they are suffering from chronic disabling conditions  because of wartime exposures to vaccines, as well as chemical warfare  agents, pesticides, and other hazardous substances with known or  suspected adverse health effects. When the issue of the possible exposure  of troops to low levels of chemical warfare agents was first raised, during  the summer of 1993, DOD and the CIA concluded that no U.S. troops were  exposed because (1) there were no forward-deployed Iraqi chemical  warfare agent munitions and (2) the plumes—clouds of chemical warfare  agents—from the bombing that destroyed the Iraqi chemical facilities  could not have reached the troops.
This position was maintained until 1996, when DOD publicly disclosed that  U.S. troops destroyed a stockpile of chemical warfare agent munitions  after the Gulf War in 1991, at a forward-deployed site, Khamisiyah, in Iraq.  Consequently, DOD and the CIA conducted several analyses using  computer modeling, in an effort to estimate the number of troops that  might have been exposed to chemical warfare agents. Recognizing that  actual data on the source term—such as the quantity and purity  (concentration) of the agent—and the meteorological conditions—such as  the wind and the weather patterns—were not available, in 1996 and 1997,  DOD and the CIA conducted field-testing and modeling of the demolition  of Khamisiyah, to determine the size and path of the plume, as well as the  number of U.S. troops exposed to chemical warfare agents within the area  of the modeled plume’s path. During these initial modeling efforts, DOD  also asked the Department of Energy’s (DOE) Lawrence Livermore  National Laboratories (LLNL) to conduct modeling. In 1997, DOD and the  CIA also combined the results of five different meteorological and  dispersion models into a composite simulation of the plume area. They  conducted additional simulations, using meteorological and dispersal  models, to estimate the path of exposure from plumes during the  bombings of sites other than Khamisiyah—Al Muthanna, Muhammadiyat,  and Ukhaydir. In 2000, DOD revised its modeling estimates for the  destruction of chemical warfare agents at Khamisiyah, and estimated that  101,752 U.S. troops had potentially been exposed.
In response to your request, we evaluated how well conclusions—about  the extent of exposure of U.S. troops and the association between CW  exposure and troops’ hospitalization and mortality rates—are supported  by available evidence.  Specifically, we have assessed the following:  1.  How valid is the DOD and MOD conclusion---based on CIA and DOD  plume-modeling results—about U.S. and British troops’ exposure to  CW agents?    2.  What were the costs for the CIA’s and DOD’s various plume modeling  efforts?   3.  How valid are the DOD and Department of Veterans Affairs (VA)  conclusions from epidemiological studies, based on DOD’s plume  modeling results, that there was no association between CW exposure  at Khamisiyah and the troops’ hospitalization and mortality rates?
subsections: section_title: Scope and Methodology
paragraphs: To determine the validity of DOD’s conclusion—that U.S. troops’  exposures to chemical warfare agents were as DOD estimates suggested— based on its plume-modeling analysis, we examined the meteorological  and dispersion models DOD used to model chemical warfare agent  releases from the U.S. demolition of Khamisiyah and Coalition bombings  of Al Muthanna, Muhammadiyat, and other sites in Iraq during the Gulf  War deployment period. We evaluated the basis for the technical and  operational assumptions DOD made in (1) conducting the modeling for the  bombing and demolition of Iraqi sites and   (2) estimating the specific data and information used in the modeling,  relating to source term, meteorological conditions, and other key  parameters. We also evaluated the efforts of the CIA and DOD to collect  and develop data on source term and other key parameters used in the  modeling efforts.
We interviewed DOD and CIA modelers and officials involved with the  modeling and obtained documents and reports from DOD’s Deployment  Health Support Directorate. We also interviewed and received documents  from DOE officials who were involved with the modeling at LLNL. In  addition, we interviewed officials and obtained documents from the  Institute for Defense Analyses (IDA) concerning the IDA expert panel  assessment of CIA’s modeling of Khamisiyah. We also interviewed U.S.  Army officials at Dugway Proving Ground, Utah, to determine how  chemical warfare agents might have been released during the Khamisiyah  pit area demolitions. Finally, we interviewed officials at the U.S. Army  Center for Health Promotion and Preventive Medicine, to determine how  specific troop unit exposures were identified, and officials of the United  Nations Monitoring, Verification, and Inspection Commission (UNMOVIC),  to obtain information on source term data from the United Nations Special  Commission’s (UNSCOM) analyses and inspections of the Khamisiyah, Al  Muthanna, Muhammadiyat, and other sites.
To determine the validity of DOD’s and the Department of Veterans  Affairs’ (VA) conclusions—based on epidemiological studies—that there  was no association between Khamisiyah exposure and the rates of  hospitalization or mortality, we reviewed published epidemiological  studies in which hospitalization and mortality among exposed and  nonexposed U.S. troops were analyzed. We also interviewed the study  authors and researchers and examined the Gulf War population databases  provided to the researchers by DOD in support of these studies. We  interviewed Veterans Benefits Administration officials and obtained  documents and reports on their analyses of DOD’s population databases.
We did not examine whether plume modeling data were being used by VA  to determine eligibility for treatment or compensation.
In an effort to identify the total costs associated with modeling and related  analyses of chemical warfare agent releases during the Gulf War; we  interviewed relevant officials and collected cost data from various DOD  agencies and DOD contractors who supported the modeling efforts.
To determine the extent of British troops’ exposure to chemical warfare  agent-related releases during the Gulf War, we interviewed British Ministry  of Defense (MOD) officials in London and at Porton Down, and reviewed  U.K. Ministry of Defense reports concerning the potential effects of  exposure to chemical warfare agent-related releases on British forces.
We conducted our work from May 2002 through May 2004 in accordance  with generally accepted government auditing standards.
section_title: Background
paragraphs: According to the CIA, modeling is the art and science of using  interconnected mathematical equations to predict the activities of an  actual event. In this case, modeling was used to determine the direction  and extent of the plume from chemical warfare agents. In environmental  hazard modeling, simulations recreate or predict the size and path (that is,  the direction) of the plume, including the potential hazard area, and  potential exposure levels are generated.
subsections: section_title: Information for Modeling
paragraphs: In addition to identifying the appropriate event to model, modeling  requires several components of accurate information:  the characteristics or properties of the material that was released and its  rate of release (for example, quantity and purity; the vapor pressure; the  temperature at which the material burns; particle size; and persistency and  toxicity); temporal information (for example, whether chemical agent was  initially released during daylight hours, when it might rapidly disperse into  the surface air, or at night, when a different set of breakdown and  dispersion characteristics would pertain, depending on terrain, plume  height, and rate of agent degradation);   data that drive meteorological models during the modeled period (for  example, temperature, humidity, barometric pressure, dew point, wind  velocity and direction at varying altitudes, and other related measures of  weather conditions);   data from global weather models, to simulate large-scale weather patterns,  and from regional and local weather models, to simulate the weather in  the area of the chemical agent release and throughout the area of  dispersion; and information on the potentially exposed populations, animals, crops, and  other assets that may be affected by the agent’s release.
section_title: Types of Models Used
paragraphs: Various plumes during the 1991 Gulf War were estimated using global- scale meteorological models, such as the National Centers for  Environmental Prediction Global Data Assimilation System (GDAS) and  the Naval Operational Global Atmospheric Prediction System (NOGAPS).  Regional and local weather models were also used, including the Coupled  Ocean-Atmosphere Mesoscale Prediction System (COAMPS), the  Operational Multiscale Environmental Model with Grid Adaptivity  (OMEGA), and the Mesoscale Model Version 5 (MM5).
Transport and diffusion models were also used during the 1991 Persian  Gulf War plume simulation efforts. These models estimate both the path  of a plume and the degree of potential hazard posed by the chemical  warfare agents. Dispersion models used during the Gulf War included the  Hazard Prediction and Assessment Capability (HPAC) along with its  component, the Second-order Closure Integrated Puff (SCIPUFF) model;  the Vapor, Liquid, and Solid Tracking (VLSTRACK) model; the Non- Uniform Simple Surface Evaporation (NUSSE) model; and the  Atmospheric Dispersion by Particle-in-Cell (ADPIC) model.
section_title: DOD’s Conclusion about U.S. Troops’ Exposure to Chemical Warfare Agents Cannot Be Adequately Supported
paragraphs: DOD’s conclusion about the extent of U.S. troops’ exposure to chemical  warfare agents during and immediately after the Gulf War, based upon  DOD and CIA plume model estimates, cannot be adequately supported.  This is because of uncertainty associated with the source term data and  meteorological data. Further, the models themselves are neither  sufficiently certain nor precise to draw reasonable conclusions about the  size or path (that is, the direction) of the plumes.
In particular, we found five reasons to question DOD’s conclusion. First,  the models DOD and the CIA selected were in house models not fully  developed for analyzing long-range dispersion of chemical warfare agents  as environmental hazards. DOD and CIA officials selected several in-house  models to run plume simulations. For Khamisiyah and the other Iraqi sites  selected for examination, DOD selected the COAMPS and OMEGA  meteorological models and the HPAC/SCIPUFF and VLSTRACK dispersion  models. However, these models were not at the time fully developed for  modeling long-range environmental hazards.
Second, the assumptions about the source term data used in the models  are inaccurate. The source term data DOD used in the modeling for sites at  Khamisiyah, as well as Al Muthanna and Muhammadiyat, contain  significant unreliable assumptions. DOD and the CIA based assumptions  on field testing, intelligence information, imagery, UNSCOM inspections,  and Iraqi declarations to UNSCOM. However, these assumptions were  based on limited, nonvalidated, and unconfirmed data concerning (1) the  nature of the Khamisiyah pit demolition, (2) meteorology, (3) agent purity,  (4) amount of agent released, and (5) other chemical warfare agent data.  In addition, DOD and the CIA excluded from their modeling efforts many  other sites and potential hazards associated with the destruction of binary  chemical weapons, vast stores of chemical warfare agent precursor  materials, and the potential release of toxic byproducts and chemical  warfare agents from other sites.
Third, in most of the modeling performed, the plume heights were  significantly underestimated. Actual plume height would have been  significantly higher than the height DOD estimated in its modeling of  demolition operations and bombings. The plume height estimates that the  CIA provided for demolition operations at the Khamisiyah pit were 0 to  100 meters. However, neither DOD nor the CIA conducted testing to  support estimated plume height associated with the bombings of Al  Muthanna, Muhammadiyat, or Ukhaydir. According to DOD modelers,  neither plume height nor any other heat or blast effects associated with  these bombings were calculated from the models; instead, these data were  taken from DOD’s Office of the Special Assistant for Gulf War Illnesses. In  addition, according to a principal Defense Threat Reduction Agency  modeler, DOD’s data on plume height were inconsistent with other test  data for the types of facilities bombed.
Fourth, postwar field testing at the U.S. Army Dugway Proving Ground, in  Utah, to estimate the source term data did not realistically simulate the  actual conditions of the demolition operations at Khamisiyah or the effects  of the bombings at any of the other sites in Iraq. For field testing to be  effective, conditions have to be as close to the actual event as possible, but  these tests did not provide more definitive data for DOD and CIA’s models.  The tests did not realistically simulate the conditions of the demolition of  122 mm chemical-filled rockets in Khamisiyah. The simulations took place  under conditions that were not comparable with those at Khamisiyah.  There were differences in meteorological and soil conditions; the  construction material of munitions crates; rocket construction (including  the use of concrete-filled pipes as rocket replacements to provide inert  filler to simulate larger stacks); and the number of rockets, with far fewer  rockets and, therefore, less explosive materials. In addition, in the tests,  the agent stimulant used had physical properties different from those of  the actual agent.
Finally, there are wide divergences—with regard to the size and path of  the plume and the extent to which troops were exposed—among the  individual models DOD selected. The models DOD used to predict the  fallout from Khamisiyah and the other sites showed great divergence, even  with the same source term data. While the models’ divergences included  plume size and paths, DOD made no effort to reconcile them. The IDA  expert panel observed that the results were so divergent that it would not  be possible to choose the most exposed areas or which U.S. troops might  potentially have been exposed. IDA therefore recommended a composite  model, which DOD adopted. However, this approach only masked  differences in individual model projections with respect to divergences in  plume size and path. In addition, DOD chose not to include in the  composite model the results of the LLNL simulation, performed at the IDA  expert panel’s request. The LLNL simulation estimated a larger plume size  and different path from DOD’s models. The IDA panel regarded the LLNL  model as less capable than other models because it modeled atmospheric  phenomena with less fidelity. A modeling simulation done by the Air Force  Technical Applications Center (AFTAC) also showed significant  divergences from DOD’s composite model.
section_title: MOD Relied on U.S. Plume Modeling to Determine Their Troops’ Exposure to Chemical Warfare Agents
paragraphs: According to British officials, the MOD did not collect any source term or  meteorological data during the 1991 Persian Gulf War. It also did not  independently model the plume from Khamisiyah, relying instead on the  1997 DOD and CIA modeling of Khamisiyah. However, according to British  MOD officials, they were reassessing the extent of British troops’  exposure, based on DOD’s revised 2000 remodeling of Khamisiyah. We  requested from the British MOD, but did not receive, information on the  findings from this reassessment.
The MOD also determined that a number of British troops were within the  boundary of the plume in the DOD and CIA composite model. The MOD  estimated that the total number of British troops potentially exposed was  about 9,000 and the total number of troops as “definitely” within the path  of the plume, however, was about 3,800. In addition, of 53,500 British  troops deployed, at least 44,000 were estimated as “definitely not” within  the path of the plume. However, since the MOD relied exclusively on  DOD’s modeling and since we found that DOD could not know who was  and who was not exposed, the MOD cannot know the extent of British  troops’ exposure.
section_title: Total U.S. Plume- Modeling Costs
paragraphs: The DOD and CIA were the primary agencies involved in the modeling and  analysis of U.S. troops’ exposure from the demolition at Khamisiyah and  bombing of chemical facilities at Al Muthanna, Muhammadiyat, and  Ukhaydir, but several other agencies and contractors also participated.  Funding to support the modeling efforts was provided to various DOD  agencies and organizations, the military services, and non-DOD agencies  and contractors. We collected data on the direct costs these agencies  incurred or funds they spent. As shown in table 1, direct costs to the  United States for modeling the Gulf War were about $13.7 million.
section_title: DOD’s and VA’s Epidemiology-Based Conclusions on Chemical Warfare Exposure and Rates for Hospitalization and Mortality Cannot Be Adequately Supported
paragraphs: DOD and VA each funded an epidemiological study on chemical warfare  agent exposure—DOD’s on hospitalization rates and VA’s on mortality  rates. From the hospitalization study, conducted by DOD researchers, and  the mortality study, conducted by VA researchers, on exposed and  nonexposed troops, DOD concluded that there was no significant  difference in the rates of hospitalization and VA concluded no significant  difference in the rates of mortality. These conclusions, however, cannot be  supported by the available evidence. These studies contained two inherent  weaknesses: (1) flawed criteria for classifying exposure, resulting in  classification bias, and (2) an insensitive outcome measure, resulting in  outcome bias. In addition, in several other published studies of 1991  Persian Gulf War veterans, suggest an associations between chemical  warfare exposure and illnesses and symptoms have been established.
subsections: section_title: DOD and VA Used Flawed Criteria for Determining Troops’ Exposure
paragraphs: In the two epidemiological studies, DOD and VA researchers used DOD’s  1997 plume model for determining which troops were under the path of  the plume—who were estimated to be exposed—and which troops were  not—those who were estimated to be nonexposed. However, this  classification is flawed, given the inappropriate criteria for inclusion and  exclusion.
In the hospitalization study, the DOD researchers included 349,291 Army  troops “coded” as being in the Army on February 21, 1991. However, the  researchers did not report cutoff dates for inclusion in the study—that is,  they did not indicate whether these troops were in the Persian Gulf  between January 17, 1991, and March 13, 1991, the period during which the  bombings and the Khamisiyah demolition took place. Although we  requested this information, DOD researchers failed to provide it. Finally,  the total number of 349,291 troops is misleading because many troops left  the service soon after returning from the Persian Gulf and therefore would  not have been hospitalized after the war in a military hospital—another  criterion for inclusion in the study. Moreover, the researchers did not  conduct any analyses to determine what number or percentage of those  who left active duty were in the exposed or nonexposed group (including  uncertain low-dose exposure or estimated subclinical exposure). Given all  the methodological problems in this study, it is not possible to accurately  estimate the total size or makeup of the exposed and nonexposed  population that may have sought or may have been eligible for care  leading to military hospitalization.
In the mortality study, the VA researchers included 621,902 Gulf War  veterans who arrived in the Persian Gulf before March 1, 1991. Troops  who left before January 17, 1991—the beginning of the bombing of Iraqi  research, production, and storage facilities for chemical warfare agents— were included in the study. This group was not likely to have been  exposed. Therefore, including them resulted in VA’s overestimation of the  nonexposed group.
Troops who came after March 1, 1991—the period during which  Khamisiyah demolition took place—were excluded from the VA study. The  Defense Manpower Data Center (DMDC) identified 696,000 troops  deployed to the Persian Gulf, but the mortality study included only the  621,902 troops deployed there before March 1, 1991. This decision  excluded more than 74,000 troops, approximately 11 percent of the total  deployed. In addition, 693 troops who were in the exposed group were  excluded because identifying data, such as Social Security numbers, did  not match the DMDC database. VA researchers did not conduct follow-up  analysis to determine whether those who were excluded differed from  those who were included in ways that would affect the classification.
section_title: DOD and VA Used an Insensitive Outcome Measure for Determining Hospitalization Rates
paragraphs: Hospitalization rates—the outcome measure used in the hospitalization  study—were insensitive because they failed to capture the chronic  illnesses that 1991 Persian Gulf War veterans commonly report, but that  typically do not lead to hospitalization. Studies that rely on this type of  outcome as an end point are predetermined to overlook any association  between exposure and illness.
Based on DOD’s 1997 plume model, DOD’s hospitalization study compared  the rates for 1991 Persian Gulf War veterans who were exposed with the  rates for those who were nonexposed. This study included 349,291 active  duty Army troops who were deployed to the Persian Gulf. However, DOD  researchers did not determine the resulting bias in their analyses, because  they did not account for those who left the service.
The Institute of Medicine noted that the hospitalization study was limited  to Army troops remaining on active duty and to events occurring in  military hospitals. Conceivably, those who suffered from Gulf War-related  symptoms might leave active duty voluntarily or might take a medical  discharge. Hospitalization for this group would be reflected in VA or  private sector databases, but not in DOD databases. The health or other  characteristics of active duty troops could differ from those of troops who  left active duty and were treated in nonmilitary hospitals. Moreover,  economic and other factors not related to health are likely to affect the use  of nonmilitary hospitals and health care services.
This limiting of the study to troops remaining on active duty produced a  type of selection bias known as the healthy warrior effect. It strongly  biased the study toward finding no excess hospitalization among the  active duty Army troops compared with those who left the service after  the war.
section_title: Some Studies Suggest an Association between Chemical Warfare Exposure and Gulf War Illnesses
paragraphs: We found some studies that suggest an association between chemical  warfare agent exposure and Gulf War illnesses. Each of these studies has  both strengths and limitations. In one privately funded study of Gulf War  veterans, Haley and colleagues reported an association between a  syndromic case definition of Gulf War illnesses, based upon the ill  veterans’ symptomatic complaints, with exposure to chemical warfare  agents. Factor analysis of the data on symptoms was used to derive a  case definition identifying six syndrome factors. Three syndrome factor  variants found to be the most significant were (1) impaired cognition,   (2) confusion-ataxia, and (3) arthro-myo-neuropathy.
section_title: Conclusions
paragraphs: In evaluating the plume models used, the results from the DOD and CIA  modeling can never be definitive. Plume models can allow only estimates  of what happens when chemical warfare agents are released in the  environment. Such estimates are based on mathematical equations, which  are used to predict an actual event—in this case, the direction and extent  of the plume. However, in order to predict precisely what happens, one  needs to have accurate data on relative to both source term and  meteorological conditions. DOD had neither of these.
Given the unreliability of the input data, the lack of individual troop  location information, and the widely divergent results of the simulations  conducted based on varying models, DOD’s analyses cannot adequately  estimate the extent of U.S. troops’ exposure to chemical warfare agents  and other related releases. In particular, the models selected were not fully  developed for projecting long-range environmental fallout, and the  assumptions used to provide the source term data were inaccurate or  flawed. Even when models with the same source term data were used, the  results diverged. In addition, the models did not include many potential  exposure events and exposures to some key materials—for example,  binary chemical weapons, mustard agent combustion by-products, and  chemical warfare agent precursor materials. It is likely that if models were  more fully developed and more credible data for source term and  meteorological conditions were included in them, particularly with respect  to plume height as well as level and duration of exposure, the hazard area  would be much larger and most likely would cover most of the areas  where U.S. troops and Coalition forces were deployed. However, given the  lack of verifiable data for analyses, it is unlikely that any further modeling  efforts would be more accurate or helpful.
The results of DOD’s modeling efforts were, nonetheless, used in  epidemiological studies to determine the troops’ chemical warfare agent  exposure classification—i.e., exposed versus nonexposed. As we noted in  1997, to ascertain the causes of veterans’ illnesses, it is imperative that  investigators have valid and reliable data on exposure, especially for low- level or intermittent exposures to chemical warfare agents. To the extent  that veterans are misclassified as to exposure, relationships will be  obscured and conclusions misleading. In addition, DOD combined the  results of individual models that showed smaller plume size and ignored  the results of the LLNL which showed much larger plume size and  divergent plume path. Given the uncertainties in source term data and  divergences in model results, DOD cannot determine or estimate—with  any degree of certainty—the size and path of the plumes or who was or  who was not exposed.
section_title: Recommendations for Executive Action
paragraphs: In our report, we are recommending that the Secretary of Defense and the  Secretary of Veterans Affairs not use the plume-modeling data for future  epidemiological studies of the 1991 Gulf War, since VA and DOD cannot  know from the flawed plume modeling who was and who was not  exposed.
We are also recommending that the Secretary of Defense require no  further plume-modeling of Khamisiyah and the other sites bombed during  the 1991 Persian Gulf War in order to determine troops’ exposure. Given  the uncertainties in the source term and meteorological data, additional  modeling of the various sites bombed would most likely result in  additional cost, while still not providing DOD with any definitive data on  estimating who was or was not exposed.
We obtained comments on a draft of this report from VA, DOD, and CIA.  VA concurred with the recommendation that VA and DOD not use the  plume-modeling data for future epidemiological studies, since VA and  DOD cannot know from the flawed plume modeling who was and who was  not exposed. DOD did not concur with the recommendation, indicating  that to them it called for a blanket prohibition of plume modeling in the  future, where the limitations of the 1991 Gulf War may not apply.  The  intent of our recommendation is only directed at epidemiological studies  involving the DOD and CIA plume modeling data from the 1991 Gulf War  and not a blanket prohibition of plume modeling in the future. We have  clarified the recommendation along these lines. DOD concurred with our  second recommendation, indicating that despite enhancements in the  models, uncertainties will remain. CIA did not concur with our report,  indicating that it could not complete its review in the time allotted.
If you or your staff have any questions about this testimony or would like  additional information, please contact me at (202) 512-6412 or Sushil  Sharma, Ph.D., Dr.PH., at (202) 512-3460. We can also be reached by e-mail  at rhodesk@gao.gov and sharmas@gao.gov. Individuals who made key  contributions to this testimony were Venkareddy Chennareddy, Susan  Conlon, Neil Doherty, Jason Fong, Penny Pickett, Laurel Rabin, and  Katherine Raheb. James J. Tuite III, a GAO consultant, provided technical  expertise.
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