Core--Lead exposure pathways, biomarkers, health effects, & phytoremediation

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Individuals living in the Tar Creek Superfund Site (TCSS) area of Oklahoma are highly exposed to lead-contaminated mining wastes ("chat"). Approximately 42% of residents are of American Indian descent. Initial studies have found high proportions (25-63%) of young children in several of the area's towns with blood leads exceeding 10 mug/dL and identified exposure to "chat" as a major independent risk factor for elevated blood lead levels. In 1997, we began working with members of a Northeast Oklahoma community group dedicated to addressing these issues ("Local Environmental Action Demanded" [L.E.A.D.] Agency, Inc.) To develop, based on community concerns and priorities, and integrated community-based study of lead exposure pathways, biological markers of lead dose, behavioral effects, and phytoremediation strategies. In the epidemiologic component of this study, we will measure bone lead levels (using a K-x-ray fluorescence instrument) and blood lead levels among 6th, and 7th graders at four middle schools located in the TCSS. These measures will be related to scores on the Iowa Test of Basic Skills, an evaluation instrument that all students are already required to take in the 5th and 7th grades, as well as rating on a Childhood Behavioral Checklist that is administered to parents, teachers, and the students themselves. We will test the hypothesis that accumulated lead burden is a major risk factor for poor cognitive and behavioral outcomes, outcomes that have been noted to be highly prevalent in this community. In a parallel effort, we will survey indigenous vegetation on the Tar Creek Superfund Site to determine plant species diversity and spatial distribution with accompanying measurements of lead in plant tissue and soil. Our analysis will determine if patterns of indigenous vegetation predict phytoremediation processes (interaction of plants and soil lead contaminants). We will incorporate this data and collect new data on hydrogeologic, horticultural, and climatic factors to design a community- based model phytoremediation plan. We will test the hypothesis that phytoremediation can reduce high soil lead concentrations in targeted areas. Finally, we will use the bone and blood lead level data generated from epidemiologic study to target exposure assessment follow-up studies of individuals with high and low lead burdens who live in close proximity to "chat" piles, and examine spatial, ecological, home, and behavioral factors that predict whether a child develops high or low lead burdens when living in a highly contaminated environment.