Re: Some questions on Pu

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

	I meant that there would be one cancer for every 200 microgram 
inhaled (assuming the linear, no threshold theory).If you think this is 
far off, please let me know your reasons. It does agree with the animal 
data, as shown in my paper---Health Physics 32: 359-379; 1977. For acute 
effects (fibrosis), the toxic dose is about 1 mg. Where did I say that Pu 
is not "highly radiotoxic"?

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


On Sat, 15 Jun 1996, ron kathren wrote:

> Bernie --
> 
> You've got to be kidding about the inhalation of plutonium!  Inhaled Pu is
> highly radiotoxic, as has been shown in numerous animal experiments in which
> lung cancer and at higher doses pneumonitis (fatal) was induced.  Recent
> work by Sanders suggest a threshold of about 1 Gy for Pu induced lung
> cancer.  As for ingestion, Pu is only poorly absorbed from the gut, and so
> on a Bq for Bq basis, inhalation is a much greater risk.  Do I interpret
> what you said correctly, viz that 200 microgram (around 13 microcuries)is an
> acute toxic dose if inhaled?
> 
> The US Transuranium and Uranium Registirews have radiochemically analyzed
> the lungs of Pu workers who died (not from Pu poisoning!) and who donated
> their tissues.  Lung depositions in these cases have been significant and
> measurable, albeit typically orders of magnitude less than 200 microgram.
> 
> Ron
> 
> 
>  
> 
> 
> 
>  
> 
> 
>    >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
> >
> >
> >
> >
>