IIRC animals living in the Chernobyl exclusion zone have a 20-30% lower lifespan on average with a high variance (some animals lives’ might be cut in half while others may be better adapted and live more or less the same amount).

That’s fine when the alternative is extinction but not when one wants to meet their grandkids.

I think it's that a 10% chance of dying of cancer before old age is unacceptable to humans but won't have a big effect on population. Similarly, a 10% chance of birth defects isn't relevant to most species as a large proportion (often more than half) of their young die before adulthood anyway.