Study finds low battlefield hazard in depleted uranium.

The U.S. and British militaries have been taking fire for their use of tank-piercing bullets made from depleted uranium, a weakly radioactive manufacturing by-product of nuclear fuel and warheads. Critics have charged that breathing airborne debris, created when the bullets strike armor, can cause leukemia, other cancers, and birth defects. A federal study now suggests that such concerns are exaggerated.

Government tests, released last October, quantified the spread of uranium dust from a bullet's impact. Albert C. Marshall of Sandia National Laboratories in Albuquerque used these data to calculate battlefield health risks from depleted-uranium shells. He claims that his calculations are the first to quantify radiation-based risks to wounded soldiers from dissolving shrapnel and to civilians living near battlefields.

The nuclear engineer's calculations, released in late July by the national lab, indicate only small risks of leukemia or birth defects, even among the troops who breathed heavy amounts of uranium-tainted dust. That result, he finds, is consistent with medical records from U.S. soldiers from the first Gulf War.

The average U.S. adult faces a 7 percent lifetime risk of death from lung cancer, Marshall notes. That number might climb to 8.5 percent in a person who breathed a heavy dose of uranium dust, Marshall estimates. He also calculates that a child could play inside a vehicle destroyed by a depleted-uranium munition for 300 hours and outside it for another 700 hours and face an increased risk of only one death in 1,000 people from colon and lung cancers combined.

"I thought [depleted uranium] was going to be a major player," in causing health effects from radiation, Marshall says. These new calculations "changed my mind." Whether they convince the critics of the military use of depleted uranium remains to be seen.