DETERMINING ENVIRONMENTAL EXPOSURE ROUTES FOR ELEVATED LEVELS OF BLOOD PB IN KANSAS CHILDREN (Invited Presentation)

Children are the demographic most susceptible to and affected by lead (Pb) poisoning. There is evidence showing that there are still irreversible effects of intellectual impairment at levels of associated with elevated blood lead levels- BLL (i.e. greater than 15 µg/dL) One of the main sources of exposure is from soil in the vicinity of childrens’ homes. Pb contamination in soil has been recorded as being primarily from Pb-based paint, historic leaded gasoline emissions, and from Pb point-source emitters. Recently, in addition to soil, high Pb in drinking water is increasingly being shown to be a potential source of exposure. The highest risk of elevated BLL in all cases is correlated with living in an area dominated by pre-1950’s housing. Data for Pb in drinking waters were partly obtained from reports by Kansas Department of Health and Environment. As part of our preliminary study which focused on soils, two Kansas counties’ residential soils were sampled, and chemical composition was examined. Pb isotopic analysis on eight samples showed multi-source contamination in the soil. Pb isotope ratios range from 1.11 to 1.20, while concentrations range from about 50 to 9000 mg/kg. An inverse correlation between Pb concentrations and Pb isotope ratios suggests mixing between an ambient natural Pb source and one derived from a radiogenic contaminant. The latter source may be a mixture of Pb from historical leaded gasoline emissions, lead emissions from industry, and leaded paint from the older homes.

The second part of our study involves a partnership with Children’s Mercy Hospital in Kansas City. Upon identifying 20 children with capillary BLL greater than 15 mg/dL (~150 ng/g), additional venous blood and environmental samples from the childrens’ home will be collected and tested for total Pb concentration, and ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁷Pb/²⁰⁸Pb ratios. By correlating the Pb isotopic ratios of potential Pb sources in the child’s home (e.g., drinking water, soils, paint chips, occupational sources, indoor air filters, dust, spices, and cosmetics) with the blood Pb isotopic ratios, we will trace the source of Pb most responsible for the children’s blood contamination. Identifying the sources of exposure in the children’s blood will help in the environmental remediation process.