Re: ?Bioassay--More Comments

[fegallag@uci.edu (Frank E. Gallagher, III)]

Some additional considerations on when to perform bioassays might include:

1.      Separating bioassays into (a) those to confirm radiation safety
procedures are OK--called confirmatory bioassays in ANSI standards, and (b)
those to measure real doses on individuals who meet the NRC criteria for
"required to be monitored" (intakes likely of >10% of ALI)--called routine
bioassays in ANSI standards.

2.      Establishing periods between bioassays in "a" above for
administrative convenience (e.g., perhaps quarterly for adults and monthly
for declared pregnant women), and in "b" above on dosimetry considerations
(LLD, effective half-life, ALI, etc.).

3.      Using additional factors to adjust the quantities handled before
bioassays are needed based on how likely the material will become airborne.
For example, based loosely on NUREG 1400, "Air Sampling in the Workplace",
For materials:
        x1 for volatile or gaseous forms (I-125 NaI, H-3 borohydrides, etc.)
        x10 for nucleotides (for H-3, C-14 & I-125), and nonvolatile powders
        x100 for other nonvolatile liquids
        x1,000 for unencapsulated nonvolatile solids
For experimental procedures:
        x0.1 for dispersibility (cutting, grinding, heating, chemical reactions)
For containment:
        x0.1 for work on open bench top
        x1 for work in fume hood (perhaps the minimum standard for
operations likely to produce airborne activity) 
        x10 for work in glove box 

For universities, this would tend to reduce the need for bioassays to a few
bad actors (H-3 borohydrides & water in larger quantities, and I-125 NaI
used for iodinations).

Frank E. Gallagher, III, CHP
RSO, Univ. of California, Irvine   92717-2725
Voice: (714) 824-6904, Fax: (714) 824-8539
E-mail: fegallag@uci.edu

>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
>