Re: Internal vs. skin

[David Scherer <scherer@uiuc.edu>]

At 10:49 AM 2/23/96 -0600, you wrote:
>
>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.
>
The target tissues are different.  With skin contamination, the target
tissue is the basal layer over 1 cm2; with internal deposition, the target
is the entire volume of the organ.  The distance to the basal layer is
smaller than most organ dimensions.  That accounts for the differences.

You are right that the difference is an artifact of the assumptions and
calculations.  In terms of real risk indicators (effective dose or total
energy imparted), the internal dose is a greater hazard.  But as someone
previously pointed out, the regulatory risk may be a greater concern.

Dave Scherer
scherer@uiuc,edu