BIOLOGICAL MONITORING OF INORGANIC LEAD

In exposure and risk evaluation, monitoring lead biologically has seve ral advantages over technical exposure assessment. Traditionally, the concentration in blood (B-Pb) has been widely used. However, the eryth rocytes tend to become saturated, and this phenomenon causes a nonline ar relationship between B-Pb and uptake and between metabolic and toxi c effects and B-Pb. Recently, several techniques for determining lead in finger bone, tibia, or calcaneus in vivo by X-ray fluorescence have become available. Bone lead reflects long-term exposure and should pr ove valuable in epidemiologic studies. Mobilization tests have been wi dely used to monitor lead biologically. They mainly seem to reflect th e lead in soft tissues and may not be an index of total body burden, m ost of which is in the skeleton. It thus seems that, at least in adult s, mobilization tests do not provide more information than traditional lead determinations in blood and urine. A metabolic model for lead in humans is presented.