From a reader:

Jonah,
Actually, the radioactive period for DU is very long. It has a half-life of 4.5 billion years, but that is precisely why it is considered not to be dangerously radioactive. Very radioactive substances have short half lives, because the fission producing the radiation and breakdown in atomic structure occurs rapidly. The truth is that the Lincoln Memorial is probably more radioactive than DU, as marble and granite contain uranium ore, and depleted uranium is less radioactive than natural uranium. The vastly more radioactive isotopes of uranium (U-234 and U-235) have been removed, leaving a metal that is 98+% composed of the negligibly radioactive U-238.
The true danger of DU is toxicity. It is a heavy metal, and DU rounds produce uranium oxide dust which can be inhaled or ingested. But toxicity is a common component of many weapons systems. The smoke produced by solid rocket motors is highly toxic, which is why our Multiple Launch Rocket Systems batten down all the hatches before firing: the smoke will kill you.
In short, there are all sorts of reasons not to go digging around in a burned out Iraqi tank. There are many types of toxic substances and unexploded ordinance left on the battlefield. DU is no more dangerous, and perhaps less so, than many other remnants of modern battle. The war against DU usage is based solely on the fear created by the usage of the word. Uranium.