DU is somewhat less radioactive than natural uranium but still significantly above background; and uranium is also a chemical toxin. (Incidentally, so is tungsten, the best alternative for military uses.) However, since DU is hard and dense, and also because we have tons of it sitting around as a by-product of bomb-making and nuclear power, it's used for armor and for armor-piercing ammunition. After all we'd have to import most of the tungsten... but the DU is already here!

Most of the stuff you hear about depleted uranium is exaggerated--both the claims of absolute safety you hear from the political right and the claims of deadly toxicity you hear from the left. Unfortunately a web search is not likely to turn up balanced reporting as there's too much noise. But here's the depleted uranium page of the Federation of American Scientists, which is pretty balanced.

Dan Berger