WASHINGTON -- Scientists working with the Department of Defense have found evidence that a low-level exposure to sarin nerve gas -- the kind experienced by more than 100,000 American troops in the Persian Gulf War in 1991 -- could have caused lasting brain deficits in former service members.
Though the results are preliminary, the study is notable for being financed by the federal government and for being the first to make use of a detailed analysis of sarin exposure performed by the Pentagon, based on wind patterns and plume size.
The report, to be published in the June issue of the journal NeuroToxicology, found apparent changes in the brain's connective tissue -- its so-called white matter -- in soldiers exposed to the gas. The extent of the brain changes -- less white matter and slightly larger brain cavities -- corresponded to the extent of exposure, the study found.
The study was led by Roberta F. White, chairman of the department of environmental health at the Boston University School of Public Health.
Previous studies had suggested that exposure affected the brain in some neural regions, but the evidence was not convincing to many scientists. The new report is likely to revive the long-debated question of why so many troops returned from that war with unexplained physical problems.
Many in the scientific community have questioned whether the so-called Gulf War illnesses have a physiological basis, and far more research will have to be done before it is clear that those illnesses can be traced to exposure to sarin. The long-term effects of sarin on the brain are still not well understood.
But several lawmakers who were briefed on the study say the Department of Veterans Affairs is now obligated to provide increased neurological care to veterans who may have been exposed.
In March 1991, a few days after the end of the Gulf War, American soldiers exploded two large caches of ammunition and missiles in Khamisiyah, Iraq. Some of the missiles contained the nerve gases sarin and cyclosarin. Based on wind patterns and the size of the plume, the Department of Defense has estimated that more than 100,000 American troops may have been exposed to at least small amounts of the gases.
When the roughly 700,000 deployed troops returned home, about one in seven began experiencing a mysterious set of ailments, often called Gulf War illnesses, with problems including persistent fatigue, chronic headaches, joint pain, and nausea. Those symptoms persist today for more than 150,000, according to the Department of Veterans Affairs, more than the number of troops exposed to the gases.
Advocates for veterans have argued for more than a decade and a half that a link exists between many of these symptoms and the exposure that occurred in Khamisiyah, but evidence has been limited.
The study, financed by the Department of Veterans Affairs and the federal Centers for Disease Control and Prevention, is the first to use Pentagon data on potential exposure levels faced by the troops and magnetic resonance imaging to scan the brains of military personnel in the exposure zone. It found signs of brain changes that could be due to exposure, showing that troops who had been exposed at higher levels had about 5 percent less white matter than those who had little exposure.
White matter volume varies by individual, but studies have shown that significant shrinkage in adulthood can be a sign of damage.
White and other researchers studied 26 Gulf War veterans, half of whom were exposed to the gases, according to a Department of Defense modeling of the likely chemical makeup and location of the plume. The researchers found that troops with greater potential exposure had less white matter.