to be in the general-population level within 5 days of the demolition. Taking the potential first-noticeable-effects exposures and the potential low-level exposures into account and eliminating the counting of the same troops on multiple days, CIA-DOD estimated that nearly 99,000 troops might have been exposed to sarin or cyclosarin above the general-population level over the course of 4 days after the demolition of the storage pit at Khamisiyah. Those CIA-DOD findings were challenged in a US Senate report (Committee on Veterans Affairs 1998). The Senate report took issue with the method, especially the reconstruction of the pit site; with the nature of the demolition; and with the number of exposed troops.

At the request of the Senate Committee on Veterans Affairs, the Air Force Technical Applications Center (AFTAC) prepared another exposure model. The AFTAC report summary indicates that AFTAC used models different from those used by CIA-DOD to simulate atmospheric chemistry (Committee on Veterans Affairs 1998). The report indicated additional geographic areas of low-level exposure not modeled by CIA-DOD. The CIA-DOD model was reviewed by an expert panel in 1998; as stated in the Khamisiyah narrative, “this panel approved of the DOD/CIA modeling methodology but recommended a number of improvements, including revisions to the computer models used. The Special Assistant initiated improvements to the 1997 model process to obtain the highest quality of hazard area definition possible. Modeling improvements continued throughout 1998 and 1999 and culminated in redefined potential hazard areas in January 2000” (Winkenwerder 2002).

A second CIA-DOD model, a peer-reviewed revision of the first, was completed in 2000 (Rostker 2000), and a final report was released in 2002 (Winkenwerder 2002). The second CIA-DOD model differed from the first in that it incorporated updated unit-location and personnel data, revised the meteorologic models, reduced the estimates of nerve-agent release, combined the toxicity of sarin and cyclosarin (the first model used only sarin), and adjusted the general-population level to account for a briefer duration of troops’ potential exposure. Troops were considered exposed to sarin at 0.0432 mg-min/m3 and to cyclosarin at 0.0144 mg-min/m3.

Neither of the models found any troops to have been exposed to concentrations above first-noticeable-effects levels, that is, concentrations that would have been high enough to induce a particular type of chemical alarm to sound and to produce visible signs of the acute cholinergic syndrome among troops. No medical reports by the US Army Medical Corps at the time of the release were consistent with signs and symptoms of acute exposure to sarin (PAC 1996a). That is in accordance with the result of the 1997 DOD survey completed by 7,400 troops within 50 km of Khamisiyah: no reports of cholinergic effects (CIA-DOD 1997).

Two other storage sites in central Iraq, Muhammadiyat and Al Muthanna, sustained damage from air attacks during the Gulf War. Munitions containing 2.9 metric tons of sarin–cyclosarin and 1.5 metric tons of mustard gas were damaged at Muhammadiyat, and munitions containing 16.8 metric tons of sarin–cyclosarin were damaged at Al Muthanna (PAC 1996a). Atmospheric modeling by CIA-DOD determined that the nearest US personnel—400 km away—were outside the range of contamination (PAC 1996a).

To estimate potential exposures to sarin or cyclosarin released from the demolition at Khamisiyah, a number of estimation and modeling procedures have been used. Table 2.1 and the chronology that follows describe the evolution of those approaches to estimate potential exposures. It must be noted, however, that in no cases were sarin and cyclosarin measured, although a Czechoslovak chemical-decontamination unit did detect sarin in areas of northern Saudi Arabia within the timeframe of the Khamisiyah demolition, which suggested that sarin was released into the air. Furthermore, the General Accounting Office (GAO) report (GAO 2004)

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