Re: Annual Limit of Intake

["Rima, Steven D" <SDRIMA@saix367.sandia.gov>]

     I believe the problem is due to confusion over the meanings of intake 
     and uptake, and not the difference in the ALI definitions. While I am 
     not able to quote a specific reference without some looking, my 
     understanding of an INTAKE is material taken into -and deposited- in 
     the body. If an intake meant "past the lips and nose" as you asked, 
     then breathing a noble gas would result in an intake, which is not 
     possible per 10CFR20. (No ALIs are given in 10CFR20 for noble gases, 
     and only submersion DACs are provided.) An UPTAKE occurs only when the 
     radioactive material is absorbed into systemic circulation, e.g. by 
     injection into the bloodstream or by absorbtion from compartments in 
     respiratory or GI tracts. Thus every uptake is also an intake, but 
     every intake does NOT result in an uptake.
     
     
     Steven D. Rima, CHP
     Vice President, ES&H Services
     RI-TECH, Inc.
     sdrima@sandia.gov


______________________________ Reply Separator _________________________________
Subject: Annual Limit of Intake
Author:  radsafe@romulus.ehs.uiuc.edu at CCSMTP
Date:    6/21/95 1:44 PM


Hi Folks,
     
Here's one I thought was pretty straightforward, but now I'm not so 
sure.  It concerns the calculation of EDE from ALI.
     
Per ICRP 30:
     
Annual Limit on Intake (ALI):  "The activity of a radionuclide which 
taken alone would irradiate a person, represented by Reference Man, to 
the limit set by the ICRP for each year of occupational exposure."
     
Per 10 CFR 20:
     
Annual Limit on Intake (ALI):  "the derived limit for the amount of 
radioactive material taken into the body of an adult worker by 
inhalation or ingestion in a year. . . ."
     
-------
I'm confused by some semantics here.  If a worker breathes in a quantity 
X of material, then, per most standard models, he will immediately 
breath out about 32% of X (.32 X).  This means that he will retain .68X 
in the body.
     
1 ALI is considered to deliver 5,000 mrem EDE.  Thus one should be able 
to calculate the current body burden, correct it for elimination over 
time, and use a simple ratio to ALI to calculate EDE.
     
But does "taken into the body" mean "past the lips and nose," or does 
it mean "retained?"
     
If "past the lips and nose", then one has to correct bioassay 
measurements not only for elimination, but also for the component of 
uptake that immediately was breathed out.  Thus the "Time 0" body 
burden would be increased by 32% to accomodate the component of uptake 
that was immediately expelled.
     
If "retained", then one needs to calculate only a time-corrected body 
burden.
     
Which is the correct approach?  (And a reference(?)).
     
     
Thanks,
     
     
Jim Barnes, CHP
Radiation Safety Officer
Rocketdyne Division, Rockwell International