The conceptual structure of the integrated exposure uptake biokinetic model for lead in children

The integrated exposure uptake biokinetic model for lead in children was de veloped to provide plausible blood lead distributions corresponding to part icular combinations of multimedia lead exposure. The model is based on a se t oi equations that convert lead exposure (expressed as micrograms per day) to blood lead concentration (expressed as micrograms per deciliter) by qua ntitatively mimicking the physiologic processes that determine blood lead c oncentration. The exposures from air, food, water, soil, and dust are model ed independently by several routes. Amounts of lead absorbed are modeled in dependently for air, food, water, and soil/dust, then combined as a single input to the blood plasma reservoir of the body. Lead in the blood plasma r eservoir, which includes extracellular fluids, is mathematically allocated to ail tissues of the body using age-specific biokinetic parameters. The mo del calculation provides the estimate for blood lead concentration for that age. This value is treated as the geometric mean of possible values for a single child, or the geometric mean of expected values for a population of children exposed to the same lead concentrations. The distribution of blood lead concentrations about this geometric mean is estimated using a geometr ic standard deviation, typically 1.6, derived from the analysis of well-con ducted community blood studies.