The increased background radiation in the atmosphere is the source of contamination

Like all steel made post nuclear, it's "contaminated" just by how humanity has changed the global environment. We are beavers on a planetary scale, in the worst way possible. we are flooding the "valley" our planet, with excess pollutants while taking far to many resources to build our dams and feed our lodges. Its just not sustainable, like the cycle between predator and prey, a good year for the lynx is a bad year for the rabbit, we are gonna burn out like lynx and mother nature rabbit is going to eat our lunch, dinner and house.