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Iraq war service: A risk factor for bronchiolitis?

May 21, 2008

A large group of soldiers returning from Iraq have been diagnosed with bronchiolitis, a disease affecting the small airways of the lung, according to Vanderbilt University Medical Center physicians who will present their findings at the American Thoracic Society's 2008 International Conference in Toronto on Wednesday, May 21.

A total of 56 soldiers from Fort Campbell, Kentucky were evaluated for unexplained shortness of breath on exertion. Surgical lung biopsies were performed on 31 of the soldiers referred, with 29 having bronchiolitis. Most of those diagnosed with bronchiolitis had a prolonged exposure to sulfur dioxide from a sulfur mine fire near Mosul, Iraq in 2003, however, several had no known specific exposures.

The soldiers were initially evaluated with chest x-rays and computerized tomography, which were normal in almost every case. Likewise, pulmonary function tests were usually normal or near-normal. Thoracoscopic lung biopsies were required to conclusively establish the diagnosis of bronchiolitis in every case.

"All of the soldiers evaluated were physically fit at the time of deployment. On return, none of those diagnosed with bronchiolitis met physical training standards. In almost every case they were declared unfit for duty and were medically boarded with a service connected disability," said principle investigator of the research, Robert Miller, M.D., assistant professor of pulmonary and critical care medicine at Vanderbilt University.

The U.S. Department of Defense believes that the Mosul sulfur fire was deliberately set and considers it a combat-related event. It was the largest ever man-made release of sulfur dioxide and was 100 times greater than the release from the Mount Saint Helen's volcanic eruption. "Air samples collected by the U.S. Army confirmed that sulfur dioxide levels in the area were at toxic levels," said Dr. Miller.

The researchers were not surprised that such a high sulfur dioxide exposure would lead to bronchiolitis, but believe that this may be the largest series to date examining the effects of such an exposure. Even more alarmingly, five out of 31 soldiers biopsied had toxic lung injury without exposure to the Mosul sulfur fire suggesting the presence of other inhalational toxins.

"However, several soldiers were diagnosed with bronchiolitis and had no exposure history. We are concerned that there are may be many unidentified exposures putting soldiers at risk of developing bronchiolitis," said lead author Matthew King, M.D., pulmonary and critical care fellow at Vanderbilt University, who added that "soldiers from Fort Campbell were not the only ones exposed to the Mosul sulfur. Other battalions were there as well."

Bronchiolitis is known to be associated with many conditions including organ transplantation, toxic inhalation, infection and rheumatoid arthritis. In most cases, it is a diagnosis based on clinical history, x-ray and pulmonary function testing. These findings suggest that there may be another risk factor: the Iraq war.

"Bronchiolitis needs to be considered in Iraq war veterans presenting with unexplained shortness of breath on exertion," concluded Dr. King.

American Thoracic Society