No, DU is what's left over after the enrichment process has gone on. Natural uranium has two main isotopes (235 and 238). The former is the one that can be used in a bomb. The latter is not. The enrichment process increases the proportion of 235 in a sample of uranium. The "waste" is uranium that's mostly 238 and has been "depleted" of it's 235 content. The half life of 238 is several billion years, so DU isn't very radioactive. It is, however, very dense so the military has made use of it in anti-tank round in the past. They have largely stopped this, however, and changed over to tungsten which is good enough.

U can be poisonous if ingested, but the health impact claims made by sites like those our friend DC has posted are largely unproven. Many desert storm vets were exposed to or worked around DU and had no ill effects. Tungsten can be similarly poisonous if ingested in the same way and you don't see any OIF vets complaining of ill effects. This sort of thing is largely based on the fear of radioactivity (Uranium! Oh my, it must cause horrrible effects.)

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"I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind." - William Thompson, 1st Baron Lord Kelvin

"If it was so, it might be, and if it were so, it would be, but as it isn't, it ain't. That's logic!" - Tweedledee

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