Re: Some questions on Pu

[Bernard L Cohen <blc+@pitt.edu>]

The "one millionth of an ounce" is pure propaganda. For Pu, the important 
risk is not ingestion, but inhalation. A toxic inhalation dose is a about 
200 micrograms, whereas an ingestion dose is about 1 gram. Inhalation is 
a very difficult process to achieve--- in experiments with dogs, it took 
a lot of technology to arrange for the dogs to inhale appreciable 
amounts. A starting reference on these things is my paper in Health 
Physics 32, 359-379 (1977).
	There was a SNAP power source made of Pu-238 that burned up in 
the atmosphere many years ago and it does contribute some to our dose 
from Pu. I'm sure references to it can be found in UNSCEAR Reports. I 
don't remember details, but I am sure doses are a tiny fraction of 1 
mrem/year, and that would very probably apply to the case you asked about.

Bernard L. Cohen
Physics Dept.
University of Pittsburgh
Pittsburgh, PA 15260
Tel: (412)624-9245
Fax: (412)624-9163
e-mail: blc+@pitt.edu