[ RadSafe ] Sv (and rems) are NOT restricted to stochastic effects

Douglas Simpkin dsimpkin at wi.rr.com
Wed Nov 29 12:21:46 CST 2006

Perhaps it's the neurons misfiring, but I'm confused.

In the discussion of the past couple of weeks on the Po-210 
poisoning, a number of folks have indicated that the Quality Factor 
(QF) or radiation weighting factor for alphas should not be 
considered when stating the magnitude of deterministic effects. 
Rather, they presume the QF is restricted to describing stochastic effects.

This is absolutely wrong.

The QF is based on radiobiological experiments of cell killing 
effects, and you can't get much more deterministic than that! The QF 
for alphas is 20 because the alphas dump so much more energy across 
the cell nucleus, and therefore cause that much more deterministic 
biological damage compared to sparsely ionizing x rays.

Indeed, the effective dose, or effective dose equivalent, (also 
confusingly in Sv or rem) is defined only for stochastic effects. But 
that's not the concern here.

My rough estimate of 0.12 ug = 0.53 mCi (the amount of Po-210 stated 
by that great repository of societal wisdom, Wikipedia, as lethal) 
uniformly spread through the liver yields a liver dose in the 
1000-2000 rad range, or 20,000 to 40,000 rem to the liver.

Enough to mess up anyone's day.

ps. And no, I'm not apologizing for non-SI units!

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