This site has some very interesting information regarding what the United States Government Accounting Office has to say about DU:

The potential health and environmental effects of DU is well-documented and many studies warn against DU use in munitions (for a good bibliography see the WISE home page, www.antenna.nl/wise/uranium/dlit.html). Contrary to their previous statements, the US government is aware of the potential risks of inhaling DU dust in the battlefield. In 1993, the US government General Accounting Office released a report that concluded, inter alia, that inhaled insoluble oxides [which makes up more than half of the DU dust created at impact with armour] stay in the lungs longer [than a year] and pose a potential cancer risk due to radiation. Ingested DU dust can also pose both a radioactive and a toxicity risk'. 1 (GAO/NSIAD-93-90: Operation Desert Storm: Army Not Adequately Prepared to Deal with Depleted Uranium)

NATO Notes