Annual Limit of Intake

[jgbarnes@ix.netcom.com (JAMES BARNES)]

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. . . ."

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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