Validation of K x-ray fluorescence bone lead measurements by inductively coupled plasma mass spectrometry in cadaver legs

K x-ray fluorescence (KXRF) systems are being used in a growing number of epidemiologic studies to measure bone lead levels as a biological marker of accumulated lead exposure. Although validation of the KXRF technique in lead-doped phantoms and bare bone specimens has been repeatedly demonstrated, few studies have compared KXRF to chemical measurements of actual intact cadaver limbs (with skin and soft tissues). In this study, lead levels in eight amputated human legs were measured by KXRF; after dissection, levels in the bare bones were again measured by KXRF and then by inductively coupled plasma mass spectrometry (ICP-MS). We observed close agreement between the KXRF and ICP-MS measurements with correlation coefficients for both the tibia and patella greater than 0.9. In this study we provide further support for the validity of KXRF measurements, particularly with respect to the patella.