Re: Some questions on Pu

[rkathren@tricity.wsu.edu (ron kathren)]

Bernie --

Your original posting led me to believe you were talking about acute
toxicity.  Given your assumption re the LNT, your statement is reasonable
although I have not checked it to see how it agrees with BEIR or ICRP.  But
remember, this is one 'theoretical' cancer, presumably with exposure over a
50 y period, and does not take into account such factors as latency,
potentiation by smoking, or age at exposure.  And, I never said that you
said that Pu was not highly radiotoxic!

Cheers,

Ron

     >	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
>> >
>> >
>> >
>> >
>> 
>
>