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Re: ?Bioassay
K.L. Classic,
The Ohio State University recently revised its bioassay requirements. Urine
and/or thyroid bioassays are required if an individual is expected to exceed
>2% of an Annual Limit on Intake.
Regualtory Guide 8.25, Air Sampling in the Workplace, states that "worker
intakes are unlikely to exceed one one-millionth of the materials being
handled or processed." Regulatory Guide 8.9, Acceptable Concepts, Models,
Equations, and Assumptions for a Bioassay Program, states that "periodic
(bioassay) measurements should be make when cumulative exposure to airborne
radioactivity, since the most recent bioassay measurement, is greater than
or equal to 0.02 ALI." Based on these two assumptions, and by reducing the
activity by a factor of 10 (just to be conservative) a yearly threshold
limit can be determined for each radionuclide using the following formula:
(0.02 x ALI for inhlation) (1,000,000) (0.1) = yearly threshold = 2,000 ALI
The ALI for ingestion was not considered because ingestion of radioactive
material would be as a result of an accident. Regulatory Guide 8.34,
Monitoring Criteria and Methods to Calculate Occupational Radiation Doses,
states that "the potential for unlikely exposures and accident conditions
need not be considered because these events, by definition, are not likely."
OSU also had a lot of historical urine and thyroid bioassay data to support
this revision. Exceptions include minors and Declared Pregnant Women.
OSU does not perform any routine whole body counting.
If you would like any additional information, please let me know and I can
fax or mail you our documentation.
Jeanne McGuire
e-mail jmcguire@magnus.acs.ohio-state.edu
> To: IN14994 --POST
>
> From: K.L.Classic
> Subject: ?Bioassay
>
> We would be very interested in the criteria medical or educational
> institutions use to determine when a bioassay is required for those who work
> with gamma emitting radionuclides, whether urinalysis or whole-body counting
> is the method of choice, and the frequency of positive results.
>
> At our institution, anyone who works with more than 10 mCi of ANY gamma
> emitting radionuclide in one calendar quarter must have a whole body count.
> For routine bioassay we rarely have a positive result.
>
> Respond here or privately to:
>
> classic.kelly @mayo.edu
>
>
>
>