Urine Sampling cont'd - doe-std-1136-20040122

DOE-STD-1136-2004

Guide of Good Practices for Occupational Radiological Protection in Uranium Facilities

consecutive nights. This technique has been reviewed with regard to uranium (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 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

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

before batching samples 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 plate-out on conta iner walls. While samples can be preserved by acidification or

freezing, good radiochemistry techniques should ensure essentially complete recovery of any plate-out or

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

material shipping requirements. Freezing samples can preserve them, but plate-out and sedimentation upon

thawing should still be expected.

Precautions are necessary if a lab uses an aliquot for analysis and extrapolates the aliquot result to

the total sample. The aliquoting procedure should be tested using spiked samples to determine if it is

representative.

A quality control (QC) verification program should exist for laboratory analyses, including use of

known blank samples and samples spiked with known quantities of radioactivity. Ideally, the samples

should not be distinguishable by the analytical laboratory from actual worker samples. The number of QC

verification samples may range from 5% to 15% of the total samples processed by a la rge-volume program;

a small program focused on submittal of special samples following suspected intakes may have a much

higher percentage of controls. An additional QC provision may be to request the analytical lab to provide

results of their in-house QC results for independent review.

There are no standard or regulatory requirements for bioassay sample chain-of-custody provisions,

nor has there been consensus on their need. Tampering with samples has not been a widely reported or

suspected problem. Site-specific chain-of-custody requirements should be based on balancing the need

with the resources required to implement them. Some sites have no chain-of-custody requirements

associated with bioassay sample collection. At other sites, a simple seal placed on a sample container

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