pt 2 Learn from a scientist who did the worlds largest study on radon...Bernard Leonard Cohen (June 14, 1924 – March 17, 2012) was born in Pittsburgh,and was Professor Emeritus of Physics at the University of Pittsburgh. Professor Cohen was a staunch opponent to the so-called Linear no-threshold model (LNT) which postulates there exists no safe threshold for radiation exposure. His views, what was in the 1980s and 1990s considered a self-marginalizing posture had gained within 20 years support from a strong minority.He died in March 2012. No-threshold and plutonium toxicity debates He claimed: "All estimates of the cancer risk from low level radiation are based on the linear-no threshold theory (LNT) which is based solely on largely discredited concepts of radiation carcinogenesis, with no experimental verification in the low dose region of the most important applications. These risk estimates are now leading to the expenditure of tens of billions of dollars to protect against dangers whose existence is highly questionable. It is therefore of utmost importance to test the validity of this theory."[5] A conclusion with an update to the landmark study published 1995, continues: "Since no other plausible explanation has been found after years of effort by myself and others, I conclude that the most plausible explanation for our discrepancy is that the linear-no threshold theory fails, grossly over-estimating the cancer risk in the low dose, low dose rate region. There are no other data capable of testing the theory in that region. "An easy answer to the credibility of this conclusion would be for someone to suggest a potential not implausible explanation based on some selected variables. I (or he) will then calculate what values of those variables are required to explain our discrepancy. We can then make a judgement on the plausibility of that explanation. To show that this procedure is not unreasonable, I offer to provide a not-implausible explanation for any finding of any other published ecological study. This alone demonstrates that our work is very different from any other ecological study, and therefore deserves separate consideration."[6] His debates in academic periodicals and published correspondence with R. William Field, Brian J. Smith (assistant professor of biostatistics, University of Iowa), Jerry Puskin (from the U.S. Environmental Protection Agency), Sarah Darby, and Sir Richard Doll and others regarding his radon-related ecologic studies are well known.[7][8][9] Among other expert panels, the World Health Organization's International Agency for Research on Cancer discussed at length Cohen's results then concluded:"The weight of evidence is that the ecological analyses of Cohen can be rejected."[10] In March, 2011, Professor Cohen stated, reflecting on his study and its controversial results that low levels of radiation can have beneficial health effects and reduce the risks of cancer, "There is evidence on both sides. Whether low-level radiation is protective against cancer, a theory called radiation hormesis, is debated in the scientific community. Furthermore, "...[on his viewpoint, and its support found in his exhaustive studies] it could go further and say that no confounding factors (like socio-economic, geography, ethnicity, medical care access, and beyond 500 explored in the analysis) can explain the results. However, my study was designed to test the assumption that the danger of radiation is simply proportional to the radiation dose, which is the only evidence that low-level radiation may be harmful. My conclusion was that that assumption is false.".[1][6][11] Reputable scientists disagree about that;[12][13] the debate is far from over. Given the uncertain effects of low-level radiation, there is a pressing need for good quality research in this area.[14] Subsequent research would join a profound array of positions including a 1982 United Nations' work-group study -UNSCEAR- concluding: "There appear to be no nonspecific effects from low doses of radiation that result in a shortening of the life span."[

• published: 14 Apr 2015
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