most interest to Gulf War veterans because of their possible exposure from demolition of Iraqi munitions at Khamisiyah, Iraq (see discussion below).
In March 1991, during the cease-fire period, troops from the U.S. 37th and 307th Engineering Battalion destroyed enemy munitions throughout the occupied areas of southern Iraq (PAC, 1996). The large storage complex at Khamisiyah, Iraq, which contained more than 100 bunkers, was destroyed. Two sites within the complex—one of the bunkers and another site called the “pit”—contained stacks of 122-mm rockets loaded with sarin and cyclosarin (Committee on Veterans’ Affairs, 1998). U.S. troops performing demolitions were unaware of the presence of nerve agents because their detectors, which were sensitive only to lethal or near-lethal levels of nerve agents (CDC, 1999), did not sound any alarms before demolition. It was not until October 1991 that inspectors from the United Nations Special Commission (UNSCOM) first confirmed the presence of a mixture of sarin and cyclosarin at Khamisiyah (Committee on Veterans’ Affairs, 1998).
At the request of the Presidential Advisory Committee (PAC), the Central Intelligence Agency (CIA) and the Department of Defense (DoD) conducted exposure modeling to determine the extent of exposure of U.S. military personnel to the nerve agents. Since there was no air monitoring at the time of the Khamisiyah demolition, various models were employed to develop estimates of ground level concentrations of sarin and cyclosarin as a function of distance and direction from the detonation sites (PAC, 1996). The CIA–DoD report integrated four different components: (1) UNSCOM reporting and intelligence summaries of the amount, purity, and type of chemical warfare agents stored at Khamisiyah; (2) the results of experiments1 performed later at Dugway Proving Ground to simulate the demolition at Khamisiyah and thus estimate the amount of sarin and cyclosarin released, the release rate, and the associated type of release (instantaneous, continuous, or fly-out); (3) a combination of dispersion models, which incorporated meteorological conditions at the time (including wind direction), to simulate the transport and diffusion of the plume in order to estimate agent concentrations downwind; and (4) unit location information to determine the position of troops in relation to the plume’s path (CIA–DoD, 1997). The result of this modeling effort is a series of geographic maps of the Khamisiyah area that overlays known troop unit locations with the projected path of the sarin–cyclosarin plume. According to the model, the plume includes two levels of potential exposure, the first is “a first-noticeable-effects” level (approximately 1 mg/min/m3), where the estimated exposure was high enough to