Depleted Uranium in Fallujah
Fallujah was the first urban conflict where massive amounts of depleted uranium ordinance was used and the anecdotal reports like this one from the BBC have been indicating higher birth defect rates.
We really need to wait to see real data, but it is certainly a floating concern.
(Depleted uranium is the stuff left over after raw uranium is processed in centrifuges to isolate out the more active bits for nuclear bombs. There's tons of it for each bomb built. The military likes it for munitions because it is extremely dense, giving it the incredible penetrating power to punch through armor.
In theory, it's borderline radioactive safe, but there have always been questions, especially since it tends to partially vaporize in some penetrator applications leaving depleted uranium dust across the battlefield area.)