Low doses of sarin may have long-term effects
Monday, December 23, 2002

Some veterans believe that soldiers on "clean-up" missions after the Gulf War
may have been exposed to sarin nerve gas.

WASHINGTON (AP) -- Low levels of sarin nerve gas affected behavior and organ
functions in laboratory animals at least a month after exposure, suggests new
research that may provide clues to the mysterious illnesses of Persian Gulf
War veterans.

In separate Army-sponsored studies, scientists observed behavioral problems,
brain changes and immune system suppression in the animals many days after
exposure to doses that caused no immediate effects, such as convulsions or
pupil constriction.

Both studies involved rodents, and "that's a big leap to human beings," said
Melinda Roberson, a behavioral neuroscientist involved in a study still under

Even so, the studies provide new information in an area where a lack of
research has made it impossible to conclude whether Gulf veterans' illnesses
are linked to low-level sarin gas exposure.

"They are pushing back the frontiers of biological effects of low levels of
sarin. The evidence is building," said Dr. Francis O'Donnell, a medical
consultant for the Defense Department who helps track Gulf War illness

Veterans of the 1991 war have suffered from various illnesses they believe
linked to their service in the Gulf. Symptoms include chronic fatigue,
diarrhea, migraines, dizziness, memory problems, loss of muscle control and
loss of balance.

Most scientists have blamed stress. Some veterans attribute the health
problems to toxic substances they encountered in the Gulf, including sarin, a
toxic chemical weapon that is lethal at high levels. Others suggest it may be
a combination of the factors.

The Pentagon has identified about 130,000 troops it believes were exposed to
low levels of sarin in 1991 when U.S. forces destroyed a weapons depot at
Khamisiyah in southern Iraq. Some veterans believe other sarin exposures

On its Web site, the Pentagon tells veterans that "current medical evidence
indicates that long term health problems are not likely."

Dr. Robert Haley, an epidemiologist at University of Texas Southwestern
Medical Center at Dallas, has published almost two dozen studies suggesting
that some Gulf War veterans' illnesses are linked to brain damage resulting
from exposure to toxins such as sarin.

The Pentagon criticized those studies, in part because veterans Haley studied
were not downwind of Khamisiyah when the depot was destroyed. Haley said the
new research gives "biological plausibility" to his suggestion of a link to
sarin gas exposure.

The study on guinea pigs is under way at the Army Medical Research Institute
for Chemical Defense at Aberdeen Proving Ground, Maryland. Its preliminary
findings were presented in November at the Society for Neuroscience's annual
meeting in Washington.

In that study, guinea pigs were injected with nerve gas five days a week for
two weeks. Some were injected with 20 percent of the dose required to kill
half the animals and others with 40 percent of that dose.

Researcher Jim McDonough, a physiological psychologist, said that would be
much higher than the level that the Pentagon says veterans were exposed to
from the Khamisiyah depot destruction. Some veterans' groups question the
accuracy of the Pentagon's exposure estimates, insisting they were much
higher. Other researchers say there is no way to calculate the exposure
levels for sure.

Although veterans were not injected with sarin, McDonough said the
biochemical effects on the brain are the same for either exposure method. He
likened the exposures to nicotine's effects on the brain whether the nicotine
is smoked, chewed or delivered through a skin patch.

The exposed animals were examined after two hours, then at three days, 10
days, a month and 100 days. There were no changes in some physical signs the
scientists monitored, such as weight gain and temperature.

But researchers said they found significant increases in certain behaviors.

For example, 100 days after exposure, animals in the 40 percent dose group
spent significantly more time in the center of their activity chambers and
traveled greater distances in the chambers, McDonough said. Guinea pigs in
both dosage level groups also reared up on their hind legs significantly more
often at 100 days.

Roberson said researchers saw a reduction in activity by the enzyme
acetylcholinesterase, a key to controlling electrical impulses in the brain.
She said that could affect behavior. Researchers are exposing another group
of animals to verify the results.

Separately, researchers at Lovelace Respiratory Research Institute in
Albuquerque, New Mexico, known for its tobacco studies, exposed mice to
low-level doses of sarin in a three-part Army-funded study. The study, begun
in 1998, was finished last year.

The mice inhaled sarin doses an hour a day for five days and an hour a day
for 10 days. The levels were one-tenth and one-twentieth the concentrations
required to kill a human. The mice were examined a day and a month after

Researchers found that the exposures, particularly when combined with heat
stress, caused both decreases and increases in the numbers of receptor sites
in areas of the brain critical for cognition and memory, "things that might
be associated with Gulf War syndrome," said Rogene Henderson, Lovelace senior

Receptor sites are essentially docking stations for brain signals. In some
cases the changes did not appear until a month after exposure, Henderson

Researchers found that the exposure also suppressed the immune system, the
body's defense mechanism against infection and disease. Researcher Mohan
Sopori, an immunologist, said that indicates something happened to the
autonomic nervous system, which is responsible for the body's automatic
functions such as sleeping and bowel movements.