Establishing Bioassay Frequency - STD-1128-98master0137

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

Urinalysis. Urine sampling provides useful information about the amount of

plutonium excreted following an intake. After chemical isolation, the plutonium in

urine samples may be determined by various methods including: alpha

spectrometry (gas-flow proportional or surface-barrier detection), alpha counting

(zinc sulfide or liquid scintillation counting), fission track counting, and mass

spectrometry. Analytical procedures for in vitro measurement of plutonium and

other radionuclides have been published (Volchok and dePlanque, 1983; Gautier,

1983).

Urine samples should be collected away from the plutonium facility to minimize

cross-contamination. Samples should be collected in contamination-free

containers; measures should be considered for minimizing plateout on walls of

container surfaces (such as by addition of trace amounts of gold, oxalate, or nitric

acid).

Fecal Analysis. Fecal analysis is a useful procedure for evaluating the excretion of

plutonium and many other radioactive materials because more than half of the

material deposited in the upper respiratory tract is cleared rapidly to the stomach

and gastrointestinal (GI) tract.

The total fecal plus urinary elimination for the first few days after exposure,

combined with in vivo counts that might be obtained, may provide the earliest and

most accurate assessment of intake. Fecal samples taken during the second and

third day after an inhalation incident are likely to provide the most useful data

because the gastrointestinal hold-up time may vary from a few hours to a few days.

Fecal sampling is primarily a monitoring procedure for confirming and evaluating

suspected intakes, but is used at some plutonium facilities for routine periodic

monitoring as well. Workers may find fecal sampling unpleasant or objectionable,

and laboratory technicians may also have aversion to fecal sample analysis. Some

of these problems may be minimized if commercial fecal sample collection kits are

used for convenient collection and handling of samples (Fisher et al., 1982).

Collection kits also provide a means for collecting uncontaminated samples. Fecal

samples may require additional sample preparation before analysis.

5.4

ESTABLISHING BIOASSAY FREQUENCY

The bioassay measurement frequency should be based on 1) the potential risks of an intake

occurring and 2) the sensitivity of a bioassay program to detecting potential intakes. The bioassay

program sensitivity can be selected using specified intervals between measurements based on the

MDD associated with an interval.

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