check out the epa blue book. the conclusions of beir vii point towards linear no threshold for solid cancers and a slightly different curve for leukemia.
Interesting. My view as a dilettante on the sidelines was that LNT was on it's way to being discredited. i.e. along the lines of the last paragraph here: https://rationalwiki.org/wiki/Linear_no-threshold
I'd be interested to know more about the current balance of thinking on the topic. The optimist in me obviously would prefer a less awful relationship between exposure and mortality but sadly I can't impose my wishes on reality.