Professor Emeritus of Physics at the University of Pittsburgh. Professor Cohen was a staunch opponent of the so-called Linear no-threshold model (LNT) which postulates there exists no safe threshold for radiation exposure:
(Michael Hart, book, Michael Kelly, review) USofA - Hubris: The Troubling Science, Economics & Politics of Climate Change03.Oct.2016
This is a book review or "Hubris: The Troubling Science, Economics and Politics of Climate Change" by Michael Hart. Review by Michael Kelly: “The global climate is changing, and has always been changing. The earth has warmed by 1C over the last 150 years. That is not the issue. The issue is whether the human emissions of carbon dioxide since 1850 are heralding an imminent and certain global climate catastrophe that could be averted by engineering projects."
Bobby Scott, scientist emeritus at Lovelace Respiratory Research Institute, Albuquerque, NM: Findings reported here point out the lack of any solid evidence for cancer induction by low radiation doses (< 100 mGy) such as are received from single or several applications of CT or chest X-rays. Particularly disturbing is the application of the Linear No-Threshold model. The notion that multiple uses of diagnostic imaging, when separated by weeks or months or longer, is cumulative with respect to damage induction, is not supported by the fact that lifetime exposure to ionizing radiation in regions of elevated background radiation does not increase cancer risk. The claims of harm from such exposures are based mainly on seriously flawed epidemiological studies that usually rely on the unscientific and forced LNT default model.
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.