The exposure limits are based on the number of cancers from Fukushima, Nagasaki, and Hiroshima, them extrapolated down to tolerable population limits (reduce ex

The exposure limits are based on the number of cancers from Fukushima, Nagasaki, and Hiroshima, them extrapolated down to tolerable population limits (reduce exposure until signal is below background). A multiplier was added in to account for the fact that radiation workers (x-ray techs, power plant staff, etc) are at far more risk of slipping above background than the general public. The noise is non-trivial: 1 in 4 Americans will be diagnosed with cancer at some point.