When the resident signed the Department of Defense Authorization legislation this week, he signed into law an amendment authored and introduced by Rep. Jim McDermott, D-Wash., ordering a comprehensive study on possible adverse health effects on soldiers from the military's use of depleted uranium.

McDermott called it, "A victory years in the making," and he went on to say that, "It is our duty and responsibility to protect and defend the soldiers who protect and defend America."

Depleted uranium is a by-product of the uranium enrichment process. Because it is very dense, the U.S. military uses depleted uranium for munitions like armor-piercing bullets and tank shells, and as a protective shield around tanks. When used in munitions, depleted uranium pulverizes into a fine dust upon impact; it can hang in the air, be inhaled or seep into the soil.

During the Gulf War, the U.S. military used approximately 300 metric tons of depleted uranium as munitions. To date in the Iraq War, approximately 150 metric tons have been used. During conflicts in Bosnia, Kosovo, Serbia, and Montenegro, about 12 metric tons were used. (A metric ton is slightly more than 2,200 pounds.)