Urine Sample Results - doe-std-1128-98

DOE-STD-1128-98

In vivo wound counting for plutonium or americium is usually one facet of special

bioassay following a wound. While a portable alpha survey meter may show if

surface contamination is present at the wound site or contamination of the wounding

object, alpha detectors are not capable of measuring imbedded activity or activity

masked by blood or serum. Thus, plutonium and americium facilities should have

available a wound counter utilizing a thin sodium iodide or semi-conductor (e.g.,

planar germanium) detector. Such detectors are capable of measuring the low-energy

photons emitted from plutonium and americium. The ability to accurately quantify

wound activity is highly variable, depending on the calibration of the equipment and

how deeply imbedded material is in the wound. If the object causing a wound and

blood smears taken at the time of a wound show no detectable activity, then a wound

count also showing no detectable activity is probably sufficient to rule out an intake.

If the wounding object or the blood smears show detectable activity, special urine

samples should be obtained regardless of the wound count result. In this latter

circumstance, lack of detectable activity on a wound count could be attributable to

deeply imbedded material at the wound site or to rapid transportation of material

from the wound to the systemic compartment.

In growth of 241Am from 241Pu in plutonium mixtures can also significantly impact in

vivo data interpretation. Rather than decreasing with time, 241Am results can increase

without additional intake. This circumstance is particularly likely if dealing with

residual activity bound up in wound sites, but may also be observed by in vivo chest

or skeleton counting. A method to evaluate 241Am in growth is described is Section

5.8.4.

5.7.2

Urine Sample Results

Detection of plutonium or americium activity in a routine or special urine sample

using commonly available radiochemical measurement techniques should be

investigated as a potential intake. A data review should be made to assure that the

sample result was correctly determined, and batch QC sample data should be

verified.

If the result is near the Lc, it is possible that statistical fluctuation of the measurement

process could account for the apparent detection. Recounting the final sample

preparation once or twice can be a helpful technique to verify a result or classify it as

a false-positive. If the first recount also detects the analyte, it can be concluded that

the sample does contain the analyte (the likelihood of two consecutive false positives

at a 5% type I error per measurement is 0.0025, or 0.25 %.) If the first recount does

not detect the analyte, a second recount can be performed as a tie-breaker.

An investigation should be initiated for any abnormal plutonium or americium

urinalysis result. "Abnormal" for a person with no prior history of intake should be

interpreted as any detectable activity.

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