Re: Medical and/or University Bioassay Programs

["Kathleen Hintenlang" <KATHLEEN@pliny.ehs.ufl.edu>]

Date sent:      Wed, 14 Feb 1996 16:24:58 -0800
Send reply to:  Medical Physics Network <MEDPHYS@CMS.CC.WAYNE.EDU>
From:           "Frank E. Gallagher, III" <fegallag@UCI.EDU>
Subject:        Re: Medical and/or University Bioassay Programs
To:             Multiple recipients of list MEDPHYS <MEDPHYS@CMS.CC.WAYNE.EDU>

>We are curious to know if anyone is performing routine bioassay for
>anything other than iodine and tritium, and if not, how do they
>justify not doing it?  (For example how do you justify that a
>nuc med tech's uptake of technetium, gallium, thallium, indium etc or
>a researcher using P-32 etc is less than the 10% ALI.)
>
One way to justify not doing bioassays for most radionuclides is to use the
methods of the recent NRC Draft Publication NUREG-1400, "Air Sampling in the
Workplace."  This publication contains equations relating Brodsky's Magic
Number (1 E -6), which is the fraction of material handled which might be
taken into the body, ALI's, release fractions based on form (volatile
liquids, powders, etc.), and a number of other modifying factors, including
confinement.  While the primary basis of the document is determining the
need for air sampling, Table 1.3 contains guidance for determining intakes
by breathing zone air sampling and/or bioassay measurements.  The calculated
activities requiring bioassays are very high--perhaps a tad too high.

I am a member of Working Group ANSI N13.39 which is writing an ANSI standard
"Internal Dosimetry Programs--Minimum Requirements".  We are in the early
draft stage, but are wrestling with an appendix which modifies the NUREG
methods a bit, but still gives fairly high values for doing bioassays.  We
have defined two main kinds of bioassays:

     1) Confirmatory Bioassays for administrative purposes to confirm that
intakes are zero or negligible by doing bioassays for only some potentially
exposed workers or at frequencies determined by administrative convenience.
These might be done for workers who are likely to receive intakes greater
than 1% or 2% of the most restrictive ALI in a year.  This would be the only
appropriate category for nearly all clinical and academic lab workers.

     2) Routine Bioassays for regulatory compliance for individuals who are
likely to receive intakes greater than 10% of the most restrictive ALI in a
year.  The frequency would be related to potential "missed dose".  This
sounds like high level work--perhaps at DOE sites handling transuranics.

Using similar arguments, the University of California, Irvine have nearly
eliminated bioassays, even for I-125 users.  Our participation level for
confimatory monitoring for adults, other than declared pregnant women, is
now 10 mCi per iodination (not per stock container), and for declared
pregnant women and minors, a factor of 10 lower activity.  These are based
on performing weekly or less frequent iodinations and could be adjusted down
for daily work.  Bioassay frequencies are quarterly for adults, except dpw's
and monthly for dpw's and minors.

We have a great deal of historical data with bioassay measurements of zero,
or close to zero, activity in the thyroids of our radioiodine users that
helped sell our new procedures to our agreement state regulatory agency.




*******************************************************************
Frank E. Gallagher, III, CHP
Manager, Radiation Protection
  and Radiation Safety Officer
Environmental Health & Safety Office    Phone:  (714) 824-6904
University of California                Fax:    (714) 824-8539
Irvine, CA   92717-2725                 E-mail: fegallag@uci.edu
*******************************************************************