Surely, these rouge zones can be turned back into useable areas- after the bombs are defused. If there was lots of lead, then the produce from those areas would be poisonous though..
https://en.wikipedia.org/wiki/Zone_rouge
(to top that some ammo dumps were simply dumped in holes in the ground at the end of the war and are slowly diffusing there toxic compounds via under ground rivers)
Here's the sign at the SL-1 site, which is not a deep burial.[2]
[1] https://en.wikipedia.org/wiki/Onkalo_spent_nuclear_fuel_repo...