A review of EDXRS in the study of human lead metabolism

Energy dispersive x-ray spectrometry (EDXRS) techniques have been developed to measure in vivo the concentration of lead (Pb) in the bone of human subjects. One important effect that this use of EDXRS has had is to highlight the ways in which the previous best understanding of how Pb behaves in the human body is having to be adjusted. In particular, models of Pb metabolism that have been shown to account well for short-term Pb exposures and blood Pb require modification of rates of transfer to and from bone in order to account for the long-term aspects of the behavior of Pb in the body. Further, both the input function (the rate of build up of bone Pb concentration from blood Pb) and the output function (the rate of release of Pb from bone back into blood) show nonlinearity. That is, the rates are not constant; they vary with the extent of Pb exposure and age.