Fecal Sample Results - doe-std-1136-20040135

DOE-STD-1136-2004

Guide of Good Practices for Occupational Radiological Protection in Uranium Facilities

An investigation should be initiated for any abnormal uranium urinalysis result. "Abnormal" for a

person with no prior history of intake should be interpreted as any detectable activity.

Once an intake is confirmed, sufficient samples must be obtained to establish a reasonably anticipated

baseline against which future measurements can be compared. This is important both to provide future

verification of the accuracy of the assessment and to identify potential additional intakes.

The statistical fluctuation of low- level measurements can be particularly troublesome for long-term

excretion patterns. Factors of two can be easily expected due to day-to-day variability and imprecise

adherence by the worker to urine collection protocols.

5.7.3 Fecal Sample Results

Fecal samples are much more sensitive to detection of intakes than are urine samples and,

consequently, are an important part of follow-up bioassay monitoring for potential intakes initially

identified by workplace indications. Pitfalls to the data interpretation include highly variable individual

fecal voiding patterns, ranging from more than one per day to one every few days. This makes it extremely

important to know what time interval is represented by a collected fecal sample. While a single set of fecal

data can be normalized to a daily excretion rate for Reference Man, it is not likely to improve the quality

of assessment.

The preferred fecal sampling protocol following an intake is to collect all the early fecal clearance

(meaning total feces for the first 5 to 7 days). This method will allow a good estimation of inhalation or

ingestion intake, but does not readily permit discrimination of inhalation from ingestion, or identify

whether inhaled material exhibits class D, W, or Y clearance patterns. For optimum interpretation, total

fecal collection should be interpreted in light of early urine and in vivo data for preliminary estimates. The

urine data is likely to be particularly valuable in conjunction with fecal data to classify an intake as class

W or Y. Longer-term follow-up fecal samples at nominally 30, 60, and 90 days post-intake should

substantially improve the classification of material as class W or Y.

Fecal sampling can also be applied to monitor excretion at long times post-intake. One caveat in such

sampling is that a worker still active in a uranium facility may be incurring very minor chronic exposure,

which can significantly interfere with long-term interpretation of acute exposure data. Papers (Bihl et al.

1993) have discussed experience with a routine fecal sampling program.

5.7.4 Use of Air Sample Data in Internal Dosimetry

Results of air sampling and continuous air monitoring implying more than 40 DAC-hours exposure

should be used to initiate special bioassay to assess intakes of uranium. Although bioassay data are the

preferred method for assessing intakes and internal doses, air sample data can be used if bioassay data are

unavailable or determined to be inadequate or nonrepresentative. Air sample data can be used to calculate

an exposure to airborne material either in terms of DAC-hours or potential radioactivity intake as follows:

(5.5)

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