Comparison of bone lead measured via portable x-ray fluorescence across and within bones

Background: Bone lead measured via x-ray fluorescence (XRF) has been used for decades in health studies. A portable XRF device for bone lead measurement is gaining in popularity for its ease of use and shorter measurement times. Previous XRF devices have measured different bone types in order to sample both cortical and trabecular bone, in which lead has different half residence times. Objective: The portable XRF uses lower energy to measure bone lead than previous devices, and, thus, only measures the surface of the bone. Because all bones have a cortical shell, we hypothesized that portable XRF bone lead measurements would be similar regardless of the bone measured. Methods: This study tested differences in portable XRF bone lead measurements across different cortical and trabecular bones in measurements made on 31 cadavers. We also compared tissue thicknesses overlying different bones, which can impact portable XRF measurements. Results: The correlation coefficients found between bones were higher (rho ~0.4) than previous K-shell XRF bone measurements in cortical and trabecular over the same range of values (rho~0.2). The concentrations were shown to vary non-significantly across different bones within individuals.