RESUMO
Children are known to be at greater risk of exposure to lead (Pb). As Pb levels in ambient air have decreased during the last decades, the relative contribution of soil ingestion to ambient Pb exposure has increased. Using data from five cross-sectional studies conducted during 1983 to 2000 in the industrial city of Duisburg and comprising 843 children, 6-11 yr old, the aim of this study was to evaluate the contribution of Pb in soil to Pb blood levels of children in comparison to the contribution of Pb in air. Based on measurements of soil samples, the spatial distribution of Pb in soil (0-10 cm depth) was estimated for the study area. Pb exposure in ambient air was calculated using routinely monitored air quality data and Lagrange dispersion modeling. Individual exposure data were assigned using geo-coded home addresses. Multiple linear regression analysis was applied to estimate adjusted association measures. Median (95th percentile) level of Pb in soil was 206 (877) mg/kg. A simultaneous decrease in air Pb and blood Pb was observed (air: from 0.47 (0.47) to 0.03 (0.16) microg/m(3); blood: from 86 (163) to 31 (68) microg/L). Significant associations between Pb in blood and Pb in the two exposure media were found. An increase of 0.44 microg/m(3) Pb in air led to an rise in blood Pb by 155%, whereas blood Pb changed by about 63% if Pb in soil increased by 800 mg/kg. The results of the study were used for a local risk assessment and the definition of action values for Pb in soil.
