I'm a bit concerned about this one.
If the experiments with rats exposed to high altitude radiation have relevance to humans, it seems likely that we would see increased health problems in commercial airline pilots and flight attendants. That wasn't addressed here, but may be worth searching to see what info is available regarding health and mortality statistics.
http://nypost.com/2017/01/30/nasa-worried-that-cosmic-rays-are-going-to-fry-plane-passengers-brains/
If the experiments with rats exposed to high altitude radiation have relevance to humans, it seems likely that we would see increased health problems in commercial airline pilots and flight attendants. That wasn't addressed here, but may be worth searching to see what info is available regarding health and mortality statistics.
http://nypost.com/2017/01/30/nasa-worried-that-cosmic-rays-are-going-to-fry-plane-passengers-brains/