Re[2]: More on DU

[Vincent.King@DOEGJPO.COM (Vincent King)]

     Several of the statements below are misleading or incorrect.
     
     The fraction of particulate material deposited in the lung has less 
     to do with the 'weight' of uranium, as seems to be implied, as it 
     does the particle size of the airborne material.  
     
     For those particulates that are deposited in the airways and lungs, 
     the amount of material dissolving and being absorbed by body fluids 
     depends on the solubility of the particulate material and the 
     length of time the material remains in the lung without being 
     removed by other mechanisms (e.g., movement out of the lungs by 
     cilia, etc.).  Since the lungs are receiving radiation exposure 
     from the particulate material that HAS NOT been absorbed or 
     otherwise removed, this exposure may well be more significant than 
     what happens after absorption by body fluids.  
     
     (To say it more simply: If you have a lot of insoluble radioactive 
     material in your lungs for years, you can get a large lung dose; 
     the fact that it may be removed relatively quickly after it finally 
     dissolves becomes irrelevant in that case.)
     
     Finally, doesn't working in SCBAs for 'any detectable' airborne 
     uranium seem just a bit ambitious?  After all, naturally occurring 
     uranium can be 'detected' in any air sample if you collect or count 
     long enough.  The whole purpose in having Derived Air 
     Concentrations and Permissible Exposure Levels is to identify air 
     concentrations where you start implementing protective measures.  
     (And if protective measures are deemed necessary, I would begin 
     with air purifying respirators before moving straight to SCBAs).
     
     From what I've been seeing on RadSafe, it sounds like the HPs 
     associated with the Armed Forces have looked at this in depth and 
     know what they are dealing with.  Unfortunately, no amount of 
     expertise is likely to make the DU 'issue' ever go away. 
     
     Vincent King
     vincent.king@doegjpo.com


______________________________ Reply Separator _________________________________
Subject: RE: More on DU
Author:  "Caracappa; Peter F (CRD)" <caracappa@crd.ge.com> at Internet
Date:    6/10/99 2:13 PM


Two items that you have not considered that the IH people might have:  first of
all, not all of the
particulates inhaled will become absorbed in the body.  As a matter of fact, for
an element as heavy
as uranium, I would expect the uptake to be very low, though I haven't had a
chance to look up any of
the data to verify that.  Also, I can't tell if you've taken into account the
organ dose/effective
dose relationship or the fact that the total body biologically half life for
uranium is only 100
days.

And according to our friends at Sigma-Aldrich, working in any detectable
concentration of uranium
should require a self-contained breathing apparatus with a full facepiece and
operate in a
pressure-demand mode.  If this guy was cleaning tanks unprotected, there was a
serious occupational
safety shortfall somewhere along the line...

g GE Corporate Research & Development
______________________________________________
Peter F. Caracappa
Environment, Health, and Safety
Tele: 518-387-4221  Dial Comm:  8*833-4221
Fax: 518-387-6335
email: caracappa@crd.ge.com

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