[ RadSafe ] Bioassay for radioiodine

RadiationScience RadiationScience at verizon.net
Sat Aug 27 19:31:27 CDT 2011

The action levels in Reg Guide 8.20 were established before the ALIs and
MPCs in 10CRFR20 were all changed. They are based on "Old Part 20".  The ALI
value for I-125 was adjusted up by a factor of 6. Therefore, the action
levels must be increased by a factor of 6 in order to maintain the same risk

Wes Van Pelt, PhD, CIH, CHP

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Laurence F
Sent: Monday, August 15, 2011 1:59 PM
To: radsafe at health.phys.iit.edu
Subject: [ RadSafe ] Bioassay for radioiodine

In response to Jeff Kulp's question about bioassay for iodine-131 see USNRC
Regulatory Guide 8.20 at
http://pbadupws.nrc.gov/docs/ML0037/ML003739555.pdf. Also look at other
Division 8 Regulatory Guides that relate to bioassay and occupational dose
in general. 

NUREG-1556, Volume 11, contains NRC guidance for licenses of broad scope.
http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1556/v11/. The
guidance on bioassay for radioiodine is less specific than the Reg. Guide
but the references will be more recent. 

If you are interested in NUREG/CR-4884, which contains IRF's for
interpretation of bioassay results it is available on the web site of the
Galvin Library at the Illinois Institute of Technology at

If you are interested in a case study, further down this page you will find
documentation of an incident at Yale University where a percutaneous
exposure beyond regulatory limits resulted in a $12,000 civil penalty. A
missed bioassay was a factor in this incident. You are probably aware that
radioiodine is one of the few radionuclides where percutaneous exposures
occur through intact skin. 

Laurence F. Friedman, Ph.D., CHP
Senior Lecturer, Physics Department 
Illinois Institute of Technology
Room 182, Life Science
3101 South Dearborn
Chicago, IL 60616-3793
(312) 842-1789
friedmanla at iit.edu

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