Even short-term exposure to specific chemicals -- just 28 days -- when combined with stress was enough to cause widespread cellular damage in the brain and liver of rats, said Mohamed Abou Donia, Ph.D., a Duke pharmacologist and senior author of the study.
Results of the study were published in the Feb. 27, 2004, issue of the Journal of Toxicology and Environmental Health.
Abou Donia's study was designed to reproduce the symptoms of Gulf War Syndrome, a disorder marked by chronic fatigue, muscle and joint pain, tremors, headaches, difficulties concentrating and learning, loss of memory, irritability and reproductive problems. The Gulf War Syndrome symptoms have been difficult to explain because veterans outwardly appear healthy and normal, said Abou Donia. Likewise, the chemically exposed animals in Abou Donia's studies looked and behaved normally.
But a decade of neurologic research has revealed widespread damage to the brain, nervous system, liver and testes of rats exposed to 60 days of low-dose chemicals -- the insect repellant DEET, the insecticide permethrin, and the anti-nerve gas agent pyridostigmine bromide. These are the same drugs that the soldiers received during the 1990 - 1991 Persian Gulf War, and Abou Donia's rats were exposed to the same levels -- in weight adjusted doses -- as the soldiers were reportedly given.
Now, Abou Donia has demonstrated that the combination of stress and short-term exposure to chemicals (28 days) can promote cellular death in specific brain regions and injury to the liver. Moreover, the chemical trio combined with stress caused damage to portions of the brain where its protective blood-brain barrier was still intact.