There is no safe level of radiation - even of xrays. The dose is cumulative and there is even an argument for superlinear low dose rate dangers. The more we spread around the environment the greater the hazards. I read once that even cigarettes (or rather the tobacco plant) accumulate one of the daughter products of radiation decay - these sit in your lungs as alpha emitters. As for DU this stuff might be a cheap way of getting rid of your radiological waste but is a war crime in actuality. It enters the environment and maybe even the food chain in a number of ways and has a very long half life. This stuff should be locked up not spread around your enemies playgrounds or even those of your allies. Plutonium had now spread around the world largely from above grounds N tests. You might have some right now sitting in your body - most of us do. Good for random mutations not so good for life as we know it. Seriously.
