Well, there's no direct scientific proof of that, but

1) the increase in cancers (and other stuff) in Iraq and Bosnia (and US soldiers, I might add) is enormous following the use of depleted uranium.
2) even the slightest amount of radiation is enough to pose a treat to a population.


Found some stuff about it:

http://www.iacenter.org/depleted/iraqmisn.htm
http://www.inesap.org/bulletin17/bul17art04.htm
http://www.commondreams.org/views01/0114-02.htm

In short, the general tone is: research is ongoing, but it is statistically clear that something is/was wrong with the wars in iraq (first one) and in the Balkan. And that something is very probably depleted uranium, which was used on both occassions...(statistically) mass cancer increases(especially leukemia) and kidney failures in Western troops stationed there and in the local populations really says enough.

Iran's political timing is extraordinary in this thing...the US and its main allies are too tied up in Iraq to pose a serious threat to them atm, so this is the best possible time to announce such propaganda.

Of course, that's not counting cruise missiles and nukes. But afaik Iran's facilities are underground under mountain ranges and/or hidden. So good luck with that.