5.0 INDIVIDUAL MONITORING FOR INTERNAL DOSIMETRY
5.1 SCOPE OF PARTICIPATION IN INDIVIDUAL MONITORING PROGRAMS FOR
Workers considered likely to have intakes resulting in an HE,50 in excess of 100-mrem are required
by 10 CFR 835.402(c) to participate in an "internal dosimetry program." Measurements from individual
monitoring programs are needed as input to an internal dosimetry program. In the context of internal
dosimetry, individual monitoring includes routine bioassay (mentioned in 10 CFR 835.402(c)) and/or
personal air sampling (not mentioned in 10 CFR 835.402(c)). This section gives criteria for participation
in individual monitoring programs, which include baseline, routine, special, and termination or task-
ending bioassay and personal air sampling programs.
Most radiation protection programs should be capable of preventing intakes through rigorous
application of engineering and administrative controls. Under such controls, a good argument can be
made that no one is likely to have an intake resulting in a HE,50 of 100 mrem. This may reduce the need
for participation in a routine bioassay program (meaning scheduled periodic measurements) but does not
eliminate the need for confirmatory or special bioassay monitoring. Likewise, the need for an internal
dosimetry program is linked more to the potential for intake than the likelihood of intake. If sufficient
quantities of radionuclides are present or handled at a facility that accidental intakes resulting in 100-
mrem HE,50 cannot be ruled out, an internal dosimetry program must be available.
5.2 BASELINE INDIVIDUAL MONITORING: BIOASSAY
Baseline monitoring involves determining the worker's bioassay status at the start of employment or
potential exposure, and obtaining appropriate baseline measurements. Internal dosimetry programs that
must of necessity be based on air sampling have no analog for baseline bioassay monitoring.
The concept of establishing a baseline does not necessarily mean that baseline bioassay
measurements be obtained. Administrative review of the worker's history can lead to the conclusion that
baseline measurements are not needed because the expected results are readily predictable (e.g., no
detectable activity). Such a review can constitute acceptable baseline monitoring.
If baseline measurements are needed, they should be completed before performing work requiring
routine bioassay. Baseline measurements are appropriate for any of the following circumstances: (1) the
worker has had prior exposure to the pertinent radionuclides and the effective retention in the body might
exceed the screening level, (2) the exposure history is missing or inconclusive, or (3) the worker will be
working with radioactive material which may be potentially detectable in bioassay due to non-
occupational sources. Illustrations of baseline bioassay scenarios are given in Example 5.1.