Index 
Human Rights (Freedom and Security) Morality Science (Risk) Epistemology
Linear-No Threshold Dose Response Model for Effects of Ionizing Radiation I compiled the following quotes today from three articles from the internet. The first article and its quote supports the "hormesis" argument I heard in early 1980's while at Sandia. The second article presents the argument of "prudency" and "conservatism" (error on the side of safety) in support the current tight restrictions on radiation releases, e.g. from high-level nuclear waste of which I have some familiarity. Please note that in the following articles, the definition of "low-level" doses is somewhat ambiguous. The second article defines low doses as compatible with the LNT model, but identifies such low-level doses as 10's to 100's of millisieverts, the same doses the first article defines as moderate to high-level doses. So extrapolation of the linear model to the 100 or so mSv level seems supported even by the first article. But regulations demand far less radiation, 50 mrem for occupational exposure, 0.5mSv, or a factor of 200 lower than the "threshold" of observed effects of some 100 mSv. The first article addresses doses less than this threshold and finds no effects in the Atomic bomb survivors of Japan, medical radiation data, or anywhere else. The second article claims that because the linear hypothesis holds to 100 mSv (actually more) it is prudent to extend it to lower doses, despite "no evidence (see first quote, second article), in fact, according to the first article, despite evidence to the contrary. The data speaks. Let he who has ears, let him hear; yet the insanity continues. Why? http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2663584 from Radiology. April 2009 v 251(1):13-22 The linear no-threshold relationship is inconsistent with radiation biologic and experimental data. by Tubiana M, Feinendegen LE, Yang C, Kaminski JM; Department of Medicine, Centre Antoine Beclere, Paris, France. Quote from page 15 (internet display) All data suggest the existence of practical thresholds for carcinogenesis. This concept means that below the dose threshold, the carcinogenic risk, if it exists, is so small that it is without clinical importance. The fear of carcinogenesis from diagnostic x-ray examinations (eg, CT) that has been propagated is unjust. It is unethical to fuel anxiety with debatable hypotheses. LNT was a useful model half a century ago. But current radiation protection concepts should be based on facts and on concepts consistent with current scientific results and not on opinions. Preconceived concepts impede progress; in the case of the LNT model, they have resulted in substantial medical, economic, and other societal harm. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2663578/#!po=2.27273 from Radiology. April 2009 v. 251(1) p. 6-12 Risks Associated with Low Doses and Low Dose Rates of Ionizing Radiation: Why Linearity May Be (Almost) the Best We Can Do by Mark P. Little, DPhil, Richard Wakeford, PhD, [...], and Amy Berrington de Gonzalez, DPhil, (Quote from page 8) "In particular, this shows that use of a “practical” threshold, as proposed by Tubiana et al, may not be wise: Just because one cannot detect a risk does not mean that it is not there." Then in support of possible effects, a nearly incoherent medical discussion Of relevance to these epidemiologic studies is the study of stable chromosome exchanges in the peripheral blood lymphocytes of populations with protracted exposures. Chromosome changes play a major role in carcinogenesis, and there is increasing evidence that the presence of increased frequencies of chromosome aberrations in peripheral blood lymphocytes in healthy individuals could be a surrogate for the specific changes associated with carcinogenesis and could therefore be indicative of risk. | HUH??? I think these authors are saying something like "changes in chromosomes might indicate a greater chance one might get cancer". Note the triple referral to potential ("chance, might") rather than to data. Anyway, yeah?, so what? How about existing immune system repair mechanisms? even perhaps a beneficial change to cell functioning due to "chromosome aberrations" (not as likely by a long shot)?, or a non-beneficial or non-destructive change (by far the most likely change); and, if even all these are ignored, do not such deleterious effects occur because of free oxidative radicals, whatever their source? Then the authors rightly say, "Thus, linearity must extend below 1 mSv, at least for the induction of chromosome aberrations"; making explicit the assumption that "chromosome aberrations" all lead to cancer, the "no threshold" part of LNT. Turbiana et al. (above) put that notion to rest. But, ah yes, I almost forgot, "prudency", even at the cost of the effects of carbon on climate, which I am not very concerned about but many people seem to be. So ISTMRN that the current and past moral-scientific argument is something like this: "Radiation is known to cause chromosomal damage. We know this because when radiation interacts with tissue it dislodges electrons and creates oxidative radicals that can alter genetic DNA. Further we know that oxidative free radicals are associated with damage of cell functions. Further we know that damaged cell functions are associated with cancer. Therefore, without a doubt, radiation effects are associated with cancer risk. (note the last word that snuck in there). Therefore, even though we can't find such risk in epidemiology, it is prudent to assume the risks are there, to err on the side of caution to save lives, in this case potential cancers caused by the free radicals." or briefly: Prudency requires ignoring evidence. At least that is the case now, as Turbiana et al. more politely say. Perhaps it was not back then when the LNTDRM was first applied, as they also suggest, but I suspect even then it was part of an effort to reduce "effects" of peaceful uses of nuclear energy to zero to atone for the atomic bomb; because it was proposed by the same people who made the bomb; and is carried on now by their current intellectual descendants. That this attitude is still prevalent is found in the open letter to world leaders from several leading "environmentalists"; We understand that today's nuclear plants are far from perfect. Well, duh, what is perfect? But "perfection" is the standard for nuclear. The "moral" standard from which the LNT was derived and the same standard against which nuclear "fails" as does anything held to the "perfection" standard. The need to say this in the letter attests to the need to disabuse people of the totally self-destructive persistence in the face of evidence that established without a doubt the much lessor effect of nuclear than carbon (the only alternative for 80% of a power grid able to maintain sufficient supply at all times) by any measure of human misery or misfortune as well as environmental impacts, as now proven by Chernobyl and Fukushima. |