[tpeo]

Do large predators have a positive effect on human health?

I'm not trying to be funny with this, I'm just pointing out that human benefit isn't strictly increasing on all environmental factors, and that some of the evolutionary adaptation our species went through was about strictly avoiding sources of harm. Being present in the environment doesn't imply being somehow beneficial.

[dsmithatx]

Not just humans evolved in low doses of radiation but, all land creatures have. Also not all life on earth was necessarily constantly exposed to large predators.