by
Brendon Nafziger, DOTmed News Associate Editor | December 01, 2011
Linear no-threshold
Also, he noted some controversies surrounding the model most often used to gauge radiation risk. Called the linear no-threshold model, this says that any increase in radiation dose above 0 mSv incrementally increases your cancer risk. The model was developed by Hermann J. Muller, a Nobel prize-winning geneticist who introduced it in the 1920s during his studies on the effects of radiation on producing abnormal offspring in fruit flies.
However, while this model might be appropriate for setting safety standards -- it is, Hendee said, the most conservative model -- it probably should not be used to make epidemiological predictions.
"There is considerable evidence that the LNT relationship is inconsistent with findings in radiation biology and experiments on animals," he said. For instance, some studies on people with occupational exposure to low levels of radiation have actually found fewer health effects in those exposed at work when compared with non-exposed controls. And a Radiology paper in April 2009 argued that there was no evidence of a carcinogenic effect for ionizing radiation for acute exposure below 100 mSv and protracted exposure below 500 mSv.
Hendee did say that in the future, with larger patient registries, improved understanding of cellular and molecular processes and studies on sub-populations with heightened sensitivity to radiation, researchers could make better predictions of the real cancer risks of low-dose exposures. But for now, he said, the evidence isn't there.
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Steve Arey
No data makes for a good excuse
December 01, 2011 08:12
In 2007 the National Toxicology Institute's Report to Congress placed Ionizing Radiation on the Known Causes of Cancer in Humans. Of course we are already aware of that, just how much you say.?
Maybe a 676 pg. research report "Radiation from Medical Procedures in the Pathogenesis of Cancer" will give you a Reality Check. Library of Congress Catalog Number (LCCN) 99-045096
PURPOSE:
"X-rays have been a well-established cause of human Cancer for decades. This monograph was undertaken (a) to quantify what share of U.S. age-adjusted cancer mortality, for each gender, is caused by medical radiation, and (b) to check on the author's 1995 finding, based on completely different data, that exposure to medical radiation accounts for about 75% of Breast Cancer incidence in the USA. In the process of evaluating cancer mortality vs. non-cancer mortality for this monograph, it became obvious that the impact of medical radiation upon death-rates specifically from Ischemic Heart Disease also demanded evaluation."
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