SPATIAL PREDICTION OF BLOOD LEAD LEVELS IN CHILDREN IN TOLEDO, OH USING FUZZY SETS AND THE SITE-SPECIFIC IEUBK MODEL
Students in Toledo area schools were instructed on proper USEPA soil sampling guidelines and were asked to collect soil samples from their residential yards as part of an educational outreach effort. A subsample of 81 soil samples was analyzed for total lead using USEPA method 6200 for field portable x-ray fluorescence and bioavailable lead using the USEPA in vitrobioaccessibility assay and ICP-OES analysis. BLLs were predicted at each sampling site using the USEPA Integrated Exposure Uptake and Biokinetic (IEUBK) model. Predicted BLLs and various physical and socioeconomic spatial variables were then used to develop an index model using analytical hierarchy process (AHP) and weighted linear combination (WLC). Fuzzy sets were implemented in the model to account for uncertainties in the sampling method.
Soil analysis showed that 8.6% of the soil samples had total soil lead concentrations above the USEPA action level of 400 mg/kg, but 28.4% of soil samples yielded predicted elevated BLLs, suggesting the action level is set too high. It was also found that housing age had the greatest impact on the possibility of lead poisoning followed by road density, percent impervious surfaces, home value, household income and soil type. The highest risk for lead poisoning was found in the highly urbanized city center. The spatial index model paired with the unique outreach driven sampling approach proved successful at providing quality soil samples and educating the community about the risks of lead in soil in urban areas.