SALT LAKE CITY -- Evidence gathered by the CIA shows that clouds of nerve gas from the March 1991 demolition of a vast Iraqi ammunition depot may have spread over a much larger area than previously reported, raising the possibility that hundreds of thousands of American troops were exposed to very low doses of chemical weapons shortly after the Persian Gulf war.
The evidence, which was outlined at a meeting here of a special White House panel on gulf war illnesses, suggested that the chemicals wafted as far as 165 miles in a southerly direction, across thousands of square miles of the southern Iraqi desert, Kuwait and northern Saudi Arabia, where American troops were stationed.
Previously, government officials had said that harmful levels of the chemical agents could not have not traveled more than about 30 miles from the ruins of the Kamisiyah ammunition depot in southern Iraq, and that the winds had moved to the northeast, away from American troops.
There is no conclusive research to show that very low doses of nerve gas leads to chronic health problems, and many scientists have suggested that chemical weapons were unlikely to be a factor in the health problems reported by gulf war veterans. There were few reports from the battlefield of American soldiers who suffered the sorts of immediate physical symptoms expected from exposure to nerve gas.
But the new evidence appeared to alarm members of a White House panel of experts, the Presidential Advisory Committee on Gulf War Veterans' Illnesses, because the findings suggested that many more American troops were exposed to some level of chemical weapons.
"This is a much more troubling scenario," said James Turner, the chief investigator for the White House panel, which has held hearings around the country to gather evidence from ailing veterans. "It's much bigger than previous estimates have been.''
Turner said that because of inadequate Pentagon record-keeping, it was unclear exactly how many American troops might have been exposed to nerve gas if the chemicals had traveled 165 miles downwind -- but "a lot of guys were there," he said.
In fact, the wedge-shaped area described by the CIA and stretching south from Kamisiyah would cover large stretches of Iraq, Saudi Arabia and most of Kuwait, areas where hundreds of thousands of American troops were stationed in the weeks after an American-led military alliance drove the Iraqi army out of Kuwait. The depot was about 30 miles northeast of the Iraq-Kuwait border.
During often hostile questioning at Tuesday's hearing of the White House panel, officials of the CIA and the Pentagon stressed that the 165-mile radius was so preliminary and imprecise that it was of little use in determining how many American troops may have been exposed to the chemicals.
"We don't want to scare people," said Bernard Rostker, an assistant secretary of the Navy who is overseeing the Pentagon's investigation of gulf war illnesses. "There's too much uncertainty to go around scaring people with arbitrary numbers."
CIA officials said that they were attempting to create a more exact model of the possible chemical exposure from Kamisiyah, but that it was difficult because of confusion about the weather at the time of the demolition, the number of rockets destroyed at the depot and the purity of the chemicals in the rockets.
"We have felt very uncomfortable with the results we were getting," said Sylvia Copeland, a CIA official involved in the issue.
Agency officials said that recent evidence suggested that the rockets were destroyed over three days -- not two, as previously believed -- and that this could have limited the spread of the plume, since each explosion would have been smaller.
But staff members on the White House panel said that similar chemical-exposure models were prepared routinely for commercial chemical plants, and they suggested that the CIA was taking far too long to finish its study of the incident, possibly out of fear of what a worst-case scenario would show.
"This is not rocket science," said Turner. "This is modeling that is done routinely in environmental circumstances, and there is no reason why you can't do a worst-case, a moderate-case and a least-case model and let people know if they need to get to a doctor or not."
The committee's executive director, Robyn Nishimi, expressed the general frustration of the panel, telling the CIA witnesses that "the American public and U.S. troops deserve an answer -- this has been going on far too long."
The CIA also acknowledged on Tuesday that it had intelligence as early as 1986, during the Iran-Iraq war, that showed that chemical weapons had been stored at the Kamisiyah ammunition depot, although this information was never passed on to the American soldiers who actually blew up the depot in March 1991.
In a statement released on Tuesday, the staff of the White House panel said that recent revelations about the handling of intelligence regarding the Kamisiyah depot "fuels the speculation about a cover-up."
Newly declassified reports show that the CIA provided the Army with detailed warnings in November 1991, about the possibility that American troops had been exposed to chemical weapons at Kamisiyah. But the Army conducted an inadequate investigation, and the intelligence reports were filed away and forgotten for more than four years.
Copyright 1997 The New York Times Company