Answer to Question #229 Submitted to "Ask the Experts"

What is the test called that finds levels of plutonium and uranium in humans, and where can such a test be done?

You have asked a very complex question very simply. I shall try to keep the answer short. Both plutonium and uranium are slowly removed from the body naturally. The speed at which this occurs depends on the type of material that was either inhaled or swallowed. This means they can be detected in urine. The amount remaining in the body can then be calculated; unfortunately, the calculation is complex and requires knowledge about the type of material and when it entered the body.

Uranium can be detected by a number of techniques. Two of the most sensitive are Inductively Coupled Plasma Mass Spectrometry and Laser Phosphorimetry. Both techniques can measure uranium at background levels as we all have some uranium in our diet. Plutonium can be detected by chemical separation followed by alpha counting. This is a complex, lengthy, and costly process. Both materials can also be detected in the body (in vivo) using germanium detectors in a low-background counting room. The sensitivity of this method is not as great as the urine analysis, but it offers the advantage of measuring what is present and not relying on complex calculations. Quantities of either uranium or plutonium that pose an immediate health hazard can easily be detected in this way. The urine analysis can be done by commercial companies (for more information contact me directly). The in vivo counting can only be done by specialised laboratories. This service is not generally available to the public. You can see some of the equipment needed at the National Calibration Reference Centre for Bioassay and In Vivo Monitoring Web site.

Gary H. Kramer, PhD
Head, Human Monitoring Laboratory
Canadian National Calibration Reference Centre for In-Vivo Monitoring.