James Conca, contributing scientist to Forbes. Background radiation across the Earth varies from 3 mrem/yr (0.03 mSv/yr) over the oceans to 10,000 mrem/yr (100 mSv/yr) in areas of high elevation made up of granitic rocks. Thus, it is not surprising that populations subjected to radiation levels of 10,000 mrem (100 mSv) or below, either natural or man-made, show radiation effects that are not statistically different from zero.
