This two-part seminar will feature Dr. Miranda Loh and Dr. Robert Root from the University of Arizona Superfund Research Program and will focus on characterizing arsenic exposure at a former mine and smelter site in Arizona. At the Iron King Mine and Humboldt Smelter Superfund Site in Dewey-Humboldt, AZ, issues of concern include: metal contamination from mine tailings; high levels of naturally-occurring arsenic in soil and groundwater; and residents' exposure to these contaminants. Dr. Miranda Loh will describe her work characterizing exposure pathways in the Metals Exposure Study in Homes. This study investigates whether there is a relationship between living near a former mine and smelter site and children's exposure to metals, particularly arsenic and lead, via soil, dust, and water. Metals were measured in residential soil, dust, water, urine, blood, and toenail samples from multiple children in 34 households up to 5 miles from the site, and compared to national studies. To further understand potential exposures, Dr. Robert Root will describe his work combining in vitro bio-assays with molecular-scale speciation to interrogate the bioaccessibility of arsenic in mine tailings. Collected surface particles, tailings, and efflorescent salts were reacted with synthetic lung and gastric fluids and analyzed by synchrotron x-ray spectroscopy for arsenic speciation. Results show that the fraction of metals released varies by particulate type as well as by bio-fluid type, which may have implications for exposure risk.
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