Fecal Sample Results - STD-1128-98master0150

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

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 2 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 normalizing a single set of fecal data to reference man daily

excretion rate can be done, 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 five-to-seven 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

an in light of early urine and in an in vivo data for preliminary estimates. The urine data is

likely to be particularly valuable in an 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 an in such sampling is that a worker still active in an in a plutonium facility may be

incurring very minor chronic exposure, which can significantly interfere with long-term

interpretation of acute exposure data. 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 plutonium.

Although bioassay data are the preferred method for assessing intakes and internal doses, air

sample data can be used for assessing internal doses if bioassay data are unavailable or

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