Moderate Lead Poisoning: Trends in Blood Lead Levels in Unchelated Children

摘要

The appropriate clinical management of children who are moderately poisoned with lead (Pb) is under active investigation. To determine the pattern of change in blood Pb (BPb) levels in the absence of chelation therapy, we followed moderately Pb-poisoned children (initial blood Pb level 1.21-2.66 μmol/l or 25-55 μg/dl) for 6 months with repeated BPb level measurements. Chelation therapy was not administered because all the children had negative lead mobilization tests indicating limited response to the chelating agent, calcium disodium edetate (CaNa_2EDTA). Eligible children received the following interventions: notification of the health department to remediate lead hazards; reinforced educational efforts about the toxicity sources and treatment of Pb during 10 clinic and 3 home visits; and iron therapy for children with fer-ritin levels less than 16 μg/l. To quantify the lead paint hazards in the home, we combined a visual rating of the surfaces (intact to peeling) with an X-ray fluorescence (XRF) measurement of the lead content of the painted surface. The sum of these assessments is termed the home environmental score (HES). Data were analyzed from 79 children. BPb levels declined by 27%, on average, over 6 months. HES was correlated with BPb at enrollment, but neither the initial nor later HES measurements predicted BPb at other time points. The HES was highest at enrollment and declined by 50% and 75% at the second and third home visits, respectively. However, only a minority of the children (20%) achieved an HES of 0, indicating no lead paint hazards at home. Despite some ongoing Pb exposure, a parallel fall in BPb levels was observed in subgroups of children with either initially low or high HES (above or below the median HES of 37). Iron status did not account for the change in BPb levels. These data provide evidence that our measure, the HES, is quantifiably related to BPb levels in children; that this correlation is significant only prior to intervention; and that BPb levels decline in children who are moderately poisoned with Pb after they are enrolled in a comprehensive intervention program, even in the absence of chelation therapy and in the presence of ongoing lead paint exposure and Fe deficiency.