Nature is doing so well around Chernobyl because of the lack of humans. I don't have a reference to hand but I beleive that the birds in the area have a high rate of genetic defects and low reproductive success. That fact that the environment seems to be doing well is a statement of how much impact humans have on their surroundings.
I doubt "nature" and humans utilize the same repair processes. There are also a wide variety of reproduction strategies that minimize the requirement for long lasting information integrity in any single individual.
It'd be incredibly interesting to look for changes in the repair mechanisms of these organisms--especially the promoters. I bet they're being expressed at ridiculously high levels.