Like most other phenomena in this world, health effects from ionizing radiation are a probabilistic matter. Extremely high doses (say, 10,000 rems) would kill everybody, and no radiation at all would kill nobody; but in between we must work with probabilities, for example, 500 rems (in one burst and without medical treatment) is close to the median dose, killing half the exposed victims.
For radiation-induced cancers, the reliable correlations come from the Japanese atomic bomb survivors, the victims of strong X-ray and radium treatment intended to cure arthritis of the spine, and from the women employed in painting radium numerals on watch dials. All of these involved doses of at least 100 rem. The measurements are acceptably good and lie pretty well on a straight line when plotted as points in a probability vs. dose chart. When the doses are absorbed over an extended period and get smaller, as they do for the case of uranium miner, in the 1950s (before the effect was realized), the evidence gets shakier, though it still appears to continue close to the same straight line. But at very small doses, say, below 1 rem/year or tens of rems accumulated over the years, direct evidence of a correlation is unconvincing and mostly absent, and this has been expressed by the antinukes as "There is no known safe level of radioactivity." [Not even at the level of activity of human blood?] Let us now look at this via a simple analogy: the health effects of falling onto a concrete floor. No one, I would guess, would survive a fall from a height of 150 ft; at some smaller height there will be 1% of survivors, at a lower height still there will be 50%, and at zero height (lying on the floor) nobody gets hurt. I do not have the data for a curve of height vs. percentage of survivors, but they are presumably available from fire departments, hospitals, and other record keepers, but only for sufficiently large heights
¾maybe 8 ft or so.But there are surely no data on falls from a height of half an inch. You can theorize by joining the measured parts of the curve to the zero point by a straight line, by a curve, or by either with a threshold, but there are no measured data.
Is it perfectly safe to jump from a ½-inch height? Not necessarily:
If 10 million people "jump" from that "height," there could always be a Gerald Ford among them who breaks a leg, and on the way to hospital pulls himself up by the hair of the driver so that the ambulance crashes into an ammunition dump. To paraphrase Dr Gofman, "there is no safe height from which to jump onto a concrete floor."
I believe that if you prorate the numbers, this is a coarse, but essentially correct analogy, at least when judged by mathematics, physics and health. The real difference is that people understand injuries inflicted by accidental falls. If they did not, the media would scream about the danger of half-inch bumps on the sidewalk and report on the great half-inch controversy dividing the scientific community; people who injure themselves by falls from unknown causes would sue the government and paving companies for failing to warn them about the bumps; juries would award them compensation plus punitive damages; and ignorant judges would sustain such verdicts, no matter how ludicrous.
[More: The Effects on Populations of Exposure to Low Levels of Ionizing Radiation (BEIR III), Committee on the Biological Effects of Ionizing Radiation, Natl. Acad. Sciences, Washington, DC, 1980.]
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Vol. 12, No. 6
Newsletter: Access to Energy Newsletter Archive Volume: Issues Issue/No.: Vol. 12, No. 6 Date: November 29, 2004 01:55 PM Title: Disaster in India
Copyright © 2004 - Access to Energy Newsletter Archive
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