Re: The Extinction Challenge (fwd)

From: John Clark (jonkc@worldnet.att.net)
Date: Mon Aug 02 1999 - 14:33:32 MDT


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>Me:
>> An Alpha particle will kill or mutate any cell it hits, a rare neutrino that hits
>> would be almost as deadly.

>Robert J. Bradbury <bradbury@www.aeiveos.com> On Monday, August 02, 1999
>John, I'm almost certain this is incorrect.

Nope.

> Radiation doses are moderated by virtually all intervening mass.

Yep.

>The denser the mass the quicker the moderation. An alpha particle
>is a helium nucleus and gets moderated much quicker than other
>forms of radiation (because it is bigger and interacts more quickly).

A few inches of air or the thinnest tissue paper will stop an
Alpha particle that's why Plutonium, a moderately strong emitter of
Alpha particles, is pretty harmless as long as it's in one big lump
(but not too big!) outside the body; only the surface material can
gives off free particles and even those are stopped after a short distance.
Plutonium only becomes the most deadly poison on the planet when
it's in the form of a fine powder and is ingested into the body,
either by eating it or breathing it into the lungs, because every Alpha
particle then emitted will hit a living cell someplace and kill it, or far worse,
mutate it. No cell can escape the massive damage of an alpha particle.

  John K Clark jonkc@att.net

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