Lead Exposure in Young Children over a 5-Year Period using Alternative Exposure Measures with the US EPA IEUBK Model

Abstract

Background/Aim: In predicting blood lead (PbB) levels in children, the IEUBK model recommends use of site specific data for soil, house dust, ambient air, water, and diet. We evaluated the model by substituting dust fall accumulation and hand wipe data instead of house dust collected by vacuum cleaner, and exterior dust sweepings instead of soil. Most uses have been on industrial sites such as mining and smelting. Methods: Simulations were undertaken on a comprehensive data set, including measured PbB, for 108 children monitored over a 5-year period in Sydney. In contrast to all other IEUBK model studies to our knowledge, data were stratified over the age ranges from 1 to 5 years as well as using data aggregated over the time of the study for each individual. Results were compared with those obtained by mixed model analyses and structural equation modelling. Results: The geometric mean contributions to total Pb intake for a child aged 1-2 years was 0.1% for air, 42% for diet, 5.3% for water and 42% for soil and dust. The median predicted versus measured PbB values were not significantly different over age of collection for soil with petri dish dust (PDD), soil with hand wipes, or sweepings with PDD although the geometric means showed large ranges over the different ages. The predicted PbB values are strongly influenced by soil Pb. Use of site specific soil values with default dust estimates results in higher predicted PbB with the contribution of soil+dust to total Pb exposure for default estimations being 8 to 42% higher than for site specific soil and dust. Conclusions: Our results indicate that it is possible to use alternative measures of soil and dust exposure to provide reliable predictions of PbB in urban environments although very high Pb values for sweepings give an overestimation of PbB.