It's a byproduct of making "enriched uranium" for nuclear weapons and fuel. "Enriched uranium" is somewhat misleading because processors take uranium with natural levels of radioactive isotopes, primarily Uranium 238 and Uranium 235, and remove as much of the U-235 as possible. Weapons makers and nuclear plant owners want almost-pure, highly radioactive U-235. What's left behind is primarily U-238 (other isotopes remain, in very small quantities). That substance has about 40 percent less radioactivity than natural uranium and is "depleted uranium."
What makes it so important?
It's proven to be the most effective tank-killing weapon ever. A round of depleted uranium no bigger than your little finger can stop a top-of-the line tank without depleted uranium armor. The weapons get sharper as they hit and plow through thick steel. They also create fireballs of thousands of degrees, a potent combination.
What is the controversy?
As they strike, the weapons get sharper by peeling off millions of shards of burning depleted uranium. Those burning pieces become microscopic dust that can be inhaled. Depleted uranium is a mildly radioactive, toxic substance that can cause damage to live tissue and cells once inside the body.
More than a quarter of vets disabled
More than a quarter of the troops deployed in the 1991 Persian Gulf War are disabled, a rate three times greater than for World War II and Vietnam. The reason for the higher rate, especially for undiagnosed illnesses, remains a mystery.
Researchers suspect dust
Some researchers think the mildly radioactive dust that results from depleted uranium weapons is at least part of the problem. Inhaling the dust has been linked to cancer, and particles can alter the DNA of nearby cells in the lungs and other parts of the body, including infection-fighting blood cells.
Pentagon official cites risk studies
Lt. Col. Mark Melanson, a key player in the Pentagon's health program, says studies by the Army and independent labs have found that the risk from depleted uranium isn't significant. He says the lower threshold for danger is well-established.
UCLA researcher: Studies limited
Renowned cancer researcher Dr. Beate Ritz at the University of California, Los Angeles, says scientists have no idea what a "safe" level of exposure to depleted uranium dust might be. Research with human exposures is too limited, she says.
