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I am rather baffled to see how terms of radiation, effective doses, absorbed doses are mixed up in the Sievert terminology. I see a sloppy scientific standard there.

Firstly, Sievert is a unit of dose, so it is questionable to use it to measure background radiation. If there are no living creatures to absorb any dose, whom are we kidding? When they use microsieverts in medical applications, they indeed talk about dose.

Secondly, Sievert is weighted both over radiation type and tissue. And obviously, when organs are hit randomly by background radiation, weighting by tissue makes no sense. You just get some average number, under conservative assumptions.

So I see quite several loopholes to obfuscate and abuse results of Sievert measurements. The weights are politically influenced by IAEA preferences, you can be sure. Here is an example how these Sieverts can lie: they say full-body scans give 5-8 milisieverts - but here the weighting factor is probably high. So saying "ah, this radiation is just a CT scan per day" can be badly misleading. (And besides, the two weightings need not be "multiplicative". Say, beta radiation may affect organs in different proportions than gamma.)

The term "effecive dose" as it is measured captures only very approximately that difference between outside and inside radiation. It does differ much whether a particle splits at your nose tip or in your lungs. So I share Giambrone's sentiment of "effective" unscientific bias. Weighting just by radiation type is ok - but that "measurement" should be distinguished from supposed weighting by tissues as well. And it would be great if the distinction between radiation and radioactivity would be reflected in terminology (and technically possible) - but sure, fast measurements of heavy particle concentrations must be tricky.

by das monde on Mon Apr 4th, 2011 at 05:24:49 AM EST
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