Sunday, September 26, 2010
From a highly favourable review of the new book Radiation Hormesis and the Linear-No-Threshold Assumption on the Low No Threshold (LNT) by Charles L Sanders-----------------------------------------
There is no safe level of radiation.” For the last 30 years, my colleagues and I at the Energy Probe Research Foundation have held that view, and espoused it through books, media appearances and presentations to regulatory bodies, helping in no small measure to tighten Canada’s radiation standards. The science on radiation as published by official bodies, we knew, made clear that any dose of radiation, no matter how small, carries with it an additional risk of contracting cancer...
This stance is now reeling. Low levels of radiation, science is increasingly telling us, are not only safe, they are actually healthful. It may be more prudent to worry about getting too little radiation than too much...
Hormesis describes something that does harm in large doses but good in small doses. We are all familiar with such hormetic relationships, even if we don’t use the term — we need various vitamins and minerals for our survival, including ones with scary names such as arsenic, but if we overdose on some, we can suffer disability or death. The trick is to get enough to avoid a deficiency in a substance we need, but not so much that it will poison us. An even better trick is to identify the ideal dose — to be able to max out on our intake of vitamins, say, while avoiding any harm. This trick — understanding when we are getting too much of a good thing — is the essence of the rapidly growing scientific inquiry into hormesis.
The other head-scratching term in the book’s title — linear-no-threshold assumption, or LNT for short — refers to the assumption that radiation is an exception to the hormesis rule, and that radiation can never be a good thing. Unlike other substances, which have a threshold between a good dose and bad, the conventional wisdom has assumed that radiation has no threshold — every dose is bad, and the bigger the dose, the badder it gets, in a straight line relationship.
This is the linear-no-threshold assumption, with “assumption” an all-important word that needs to be taken literally. While no one disputes that high doses of radiation cause harm, no one has proof that low levels cause harm. Surprisingly, the scientists and government bodies that adhere to the LNT assumption will tell you that no proof of harm at low levels is even possible because the risk is too low to measure statistically. In the absence of proof, they say, the only prudent course is to play it safe by assuming that low levels of radiation cause harm.
But is it safe to assume that humans, who evolved in a radiation-rich environment, and who live in a world that continually bombards us with natural, background radiation, would be better off by curtailing our exposure to radiation? “Literally millions of lives are less healthy because they have been convinced that living in radiation-deficient environments is healthy; lives are lost in not implementing effective low-dose radiation therapy to treat cancer; lives are lost out of fear of diagnostic radiation that saves lives,” writes Charles Sanders, the book’s author and a participant in radiobiological research over half a century.
Mr. Sanders makes his case for the robustness of hormesis research by citing hundreds of studies ...
Take the case of “an almost perfect study in a human population that demonstrates the highly significant protective effects of near-continuous exposure to gamma radiation.” This case involved more than 180 apartment buildings that had been constructed in Taiwan in the early 1980s using recycled steel that was subsequently discovered to have been contaminated with radioactive cobalt-60. The 10,000 people who were housed there received large doses of radiation over a period of nine to 20 years that, according to LNT theory, should have led to a total of 302 cancer deaths over the 1983-2003 period studied, 232 of which would have been ordinarily expected had no radiation exposure occurred, with the additional 70 stemming from the exposure. To the researchers’ surprise, however, only seven cancer deaths were found, 225 fewer than would have been expected had the buildings been free of radiation. Instead of radiation increasing the death toll by 30%, it may have reduced the death toll by a staggering 97%.
The number of birth defects among children born in this radioactive environment also confounded LNT theory. Instead of the 48 defects expected, just three occurred...
Mr. Sanders’ book is not the first to deal with radiation hormesis and it won’t be the last — research in this field has been increasing at an exponential rate and can only grow unless it can be disproven. The safest course for society is to get on with the research.
I believe that without LNT the anti-nuclear power scares wouldn't have been feasible (3 Mile Island in particular depends on an infinitesimal leak being assumed dangerous) & that the world's nuclear electricity share would have gone up from the 20% it reached to anywhere between 50-100% over the last 40 years with consequent reductions in the cost of living & rise in the rate of growth. If world growth had been 1 1/2% higher over 40 years we would, due to compounding, be about 80% better off. This is only a guesstimate but I don't think anybody could better it.
Beyond that the refusal to use nuclear pulse rockets to reach "Mars by 1965, Saturn by 1970" was because of the test ban & fear of such tiny amounts of radiation. At the described rate we would certainly have a spacegoing civilisation across the entire solar system by now.
LNT scares have certainly cost us many 10s of millions of lives, at least a large part of the world's wealth & a spacegoing civilisation.
The eco-fascists have left us a legacy far worse than Hitler's.