Re: Internal vs. skin

[BRZGV@ccmail.ceco.com]

It is most likely assumed that an intake assumes uniform distribution in a 
particular organ of interest.  This may cause the dose/gram to be low.  If the 
same amount of activity were present over 1 cm^2, such as the case for skin, 
then I would think the dose should be similar to skin or higher.  I wouldn't 
think the surface of organs or various epithelial lining of the body have the 
same layer of essentially dead tissue which skin has and henceforth those betas 
lost in the dead layer of skin would actually be depositing energy to an organ. 
On the down side, I'm sure most of those epithelial linings also have thin films
of "mucus-like" substances which may attenuate beta as well.

I think the distribution of contamination is the main difference.
______________________________ Reply Separator _________________________________
Subject: Internal vs. skin
Author:  radsafe@romulus.ehs.uiuc.edu at INTERNET
Date:    2/23/96 10:47 AM


     
Looking at this issue from the standpoint of a layman, tissue is tissue 
whether it is on the skin or inside of someone.  The exposure should be the 
same.  It seems that difference is in the way the calculations are done.  
Please explain why this logic is wrong.
     
     
----- Begin message from IN%"radsafe@romulus.ehs.uiuc.edu"  21-Feb-96
     
From: IN%"radsafe@romulus.ehs.uiuc.edu"    21-FEB-1996 20:10
To: IN%"radsafe@romulus.ehs.uiuc.edu"  "Multiple recipients of list" 
CC: 
Subj: Internal v. skin
     
     
Regarding Kent Lambert's original post (16 Feb 1996 (Digest 826)), "One 
should keep in mind that a microcurie of an electron emitter delivers a much 
smaller dose when it is in the body that it does when it is on the the skin. 
 And skin contamination is much more likely than an uptake.  Therefore, the 
most critical concern has to be skin contamination."
     
And js_dukelow's 2/16/96 query, "Am I missing something here?"
     
If you read this with your RSO hat on,  it does make sense!  Let's take a 
look at P-32:  The dose conversion for 1 microcurie/cm2 on the skin is 8 
rem/h.  The dose conversion for 1 microcurie ingested is about 10 mrem CEDE. 
 Therefore, in just over six hours of a 1 microcurie/cm2 skin contamination 
event (assuming no removal) you have an overexposure!  On the other hand, 
(no pun intended) the ingestion event only delivers 1/600 of the ALI.  Of 
course we could get out our pencils and sharpen up the analysis, but it 
won't have much effect on the bottom line -- the skin contamination event is 
typically much more likely to cause a regulatory overexposure than an 
ingestion or inhalation event at a biomedical R&D lab.
     
This is my opinion and not necessarily the opinion of my employer.
     
glenn_sturchio@merck.com
     
     
ELI A.PORT, CHP, CIH, P.E.
RSSI
eport@nwu.edu
VOICE:847.965.1999, 24X7
FAX:  847.965.1991
     
     
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From: eport@nwu.edu (Eli A. Port)
Subject: Internal v. skin
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