[ RadSafe ] NYT Op-Ed: The Smoky Bomb Threat (on Po-210)

Bernard L. Cohen blc+ at pitt.edu
Fri Dec 22 09:07:55 CST 2006

John Jacobus wrote:

>Polonium sources with about 10 percent of a lethal
>dose are readily available - even in a product sold 
>on Amazon.com. Only modest restraints inhibit purchase
>of significantly larger amounts of polonium: as of
>next year, anyone purchasing more than 16 curies of
>polonium 210 - enough to make up 5,000 lethal doses -
>must register it with a tracking system run by the
>Nuclear Regulatory Commission.
    ---The error in this discussion of how a dirty bomb can disperse 
Polonium is that it ignores the probability for an atom so dispersed to 
be inhaled by a human. This is discussed in my paper on "Probability for 
human intake of an atom randomly released into the ground, rivers, 
oceans, and air", Health Phys 47:281-292;1984, where it is concluded 
that with dispersal in the most densely populated areas (e.g. 
Manhattan), this probability is of order 1/100,000. Thus, the amount 
dispersed would have to be 20 x 16 curies = 320 curies to cause a single 
early death. Surely anyone can think of better materials for such a 
terrorist bomb. Even chlorine gas, readily available for purchase in any 
quantity, would be much more effective, not to mention nerve gases, 
anthrax, etc.

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