Abstract of Project 2

 

Project 2 is exploring the transport and fate of metals form mine wastes (chat) in communities surrounding the Tar Creek Superfund Site potentially leading to adverse exposure in human receptors, specifically children. Although metals in chat may be relatively unavailable for geochemical mobilization or biological uptake (due to interactions with reactive sulfides), reactions releasing metals from the sulfides may be more favorable for some metals (such as Zn and Cd) over others (such as Cu and Pb). Thus, the mixture of metals to which children are exposed may be very different from the mixture of metals present in the parent chat. In addition, metals that have mobilized off of the chat piles into other exposure media such as soil, water, airborne particulates and indoor dust, have a higher relative bioavailability when compared to parent waste material.

We are seeking to understand whether this phenomenon is true, and whether the types and bioavailability of metals to which children are exposed can be better understood with a more sophisticated consideration of the underlying geochemistry of metals in mine wastes. Specifically, we are studying what metals are enriched in down-gradient exposure media relative metals in the chat, and are using sequential extraction techniques to demonstrate that metals in these down-gradient media have a higher relative bioavailability.

In conjunction with Project 1, we are also using this data to conduct a nested case-control study to examine the extent that environmental factors, including diet, explain difference in blood levels of Pb and Mn in children from the Tar Creek area. In conjunction with the animal studies (Projects 3 and 4), we are using the samples we have collected to supply those studies with well-characterized exposure material with respect to the concentrations and potential bioavailability of metals within each media.

Finally, in parallel with the exposure assessment, we are conducting micro-array experiments to demonstrate their utility as part of an overall exposure/adverse health outcome assessment.