Re[2]: Iodine Bioassay: NUREG/CR-4884

["Charles Potter" <CAPOTTE@sandia.gov>]

     My review of Supplement 1 to ICRP-30 shows the thyroid as the only 
     target and source organ listed for I-131.  Therefore, in this case, 
     the lung did not pass the significant target (10%) rule.  Your 
     argument is valid, however, for a few other isotopes of iodine.
     
     Gus Potter
     Sandia National Laboratories
     CAPOTTE@sandia.gov


______________________________ Reply Separator _________________________________
Subject: Re: Iodine Bioassay: NUREG/CR-4884
Author:  stabin@esper.com at hubsmtp
Date:    5/11/96 9:56 AM


Gus Potter wrote:
     
>     For iodine, the f1=1, meaning all iodine in the stomach goes
>     immediately to the systemic whole body, and the only inhalation class 
>     is class D meaning that there is no long term lung retention.  Since 
>     this is the case, the inhalation and ingestion models act the same
>     (after a few days after intake) except for the 37% exhalation that is 
>     assumed in the lung model.  Therefore, you should just be able to
>     multiply the ingestion IRFs by 0.37 to get those from inhalation.  To 
>     account for the radioactive isotopes, you can just multiply by the
>     decay factor.
     
Not quite.  There is some significant decay of I-131 in the lung on its way 
to the systemic circulation.  Note the difference in thyroid Us's in ICRP 30 
for inhalation and ingestion.
     
I don't have the NUREG here at home, but I will look at it when I drop in at 
work.  Between that and ICRP 54, I find it hard to believe there are no 
available IRFs for inhalation of iodines.  But if not, I can calculate some, 
and will post them.
     
Mike Stabin
Radiation Internal Dose
  Information Center
Oak Ridge, TN
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423-576-8673  fax
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