Observed and predicted long-term clearance of lead from the blood of children

Abstract

Blood lead (Pb) monitoring plays an important role in identifying children experiencing increased Pb exposure based upon their elevated blood Pb levels (PbB). Following actions to decrease Pb exposure, it is important to understand whether a slow decline in PbB is due to the slow reduction in bone Pb following prolonged exposure or due to continued exposure from an unknown source. The goal of this study was to examine the ability of the All Ages Lead Model (AALM) version 3.0 to predict long-term clearance kinetics of PbB in children. Data for six children exhibiting increased Pb exposure during home renovations lasting 4-20 months were obtained from a published study. The AALM was used to simulate PbB kinetics in children following removal of this residential renovation exposure. Quantitative analyses showed reliable agreement between predicted and observed PbB data as well as halftimes for PbB clearance, which ranged from 7.8 to 38 months. The AALM can predict long-term PbB clearance in children who were exposed to Pb for months to years during home renovations. Short-term (1 week or less) PbB clearance was most affected by exposure duration with minimal effects attributed to exposure magnitude. Long-term (months to years) PbB clearance was affected by both the magnitude and duration of renovation exposure. In addition to PbB monitoring, AALM simulations might improve understanding of probable causes for changes in and contributors to children's PbB.