Urine Sampling - STD-1128-98master0142

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

Large-volume urine samples are necessary for bioassay monitoring due to the very small

urinary excretion rates. Ideally, 24-hour total samples would be preferred; however, such

samples often impose substantial inconvenience on workers, resulting in an in

noncompliance with the instructions. As an alternative, total samples can be simulated by

either time-collection protocols or volume normalization techniques.

One method of time-collection simulation (NCRP, 1987b; Sula et al., 1991) is to collect all

urine voided from 1 hour before going to bed at night until 1 hour after rising in an in the

morning for two consecutive nights. This technique has been reviewed with regard to

uranium by Medley et al. (1994) and found to underestimate daily urine excretion by about

14%. Such a finding is not unexpected, since the time span defined by the protocol is likely

to be about 18 to 22 hours for most people.

The volume normalization technique typically normalizes whatever volume is collected to

the ICRP Reference Man daily urine excretion volume of 1400 mL. Reference Woman

excretion (1000 mL/d) may be used for gender-specific programs. As a matter of

practicality, routine monitoring programs do not usually use gender as a basis of routine data

interpretation, particularly since results are anticipated to be nondetectable under normal

conditions.

A third method calls for collection of a standard volume (e.g., 1 liter) irrespective of the time

over which the sample is obtained. This method uses the standard volume as a screening

tool only for routine monitoring. It does not attempt to relate measured routine excretion to

intake, relying on well-defined and timely supplemental special bioassay to give true or

simulated daily excretion rates.

The most common sample collection containers are 1-liter polyethylene bottles. Although

glass bottles are also used, they pose additional risks of breakage. Wide-mouthed bottles are

preferred for convenience and sanitation. The number of bottles included in an in the kit

should be appropriate to the protocol; for a total 24-hour protocol as much as 3 liters can be

expected. Special provisions, such as a funnel or transfer cup, may improve the esthetics of

sample collection and provide for added worker cooperation.

Some concerns can exist with length of sample storage before analysis. Storage may come

from delays before batching samples in an in-house or due to transportation times to an

offsite laboratory. The longer a sample stands, the more chemical and biological change it

can undergo, typically manifesting itself as sedimentation and plateout on container walls.

While samples can be preserved by acidification or freezing, good radiochemistry

techniques should assure essentially complete recovery of any plateout or sediment.

Samples sent offsite for analysis can be preserved with acid, but this method imposes

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