Residential metal contamination and potential health risks of exposure in adobe brick houses in Potosí, Bolivia.
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Potosí, Bolivia, is the site of centuries of historic and present-day mining of the Cerro Rico, a mountain known for its rich polymetallic deposits, and was the site of large-scale Colonial era silver refining operations. In this study, the concentrations of several metal and metalloid elements were quantified in adobe brick, dirt floor, and surface dust samples from 49 houses in Potosí. Median concentrations of total mercury (Hg), lead (Pb), and arsenic (As) were significantly greater than concentrations measured in Sucre, Bolivia, a non-mining town, and exceeded US-based soil screening levels. Adobe brick samples were further analyzed for bioaccessible concentrations of trace elements using a simulated gastric fluid (GF) extraction. Median GF extractable concentrations of Hg, As, and Pb were 0.085, 13.9, and 32.2% of the total element concentration, respectively. Total and GF extractable concentrations of Hg, As, and Pb were used to estimate exposure and potential health risks to children following incidental ingestion of adobe brick particles. Risks were assessed using a range of potential ingestion rates (50-1000mg/day). Overall, the results of the risk assessment show that the majority of households sampled contained concentrations of bioaccessible Pb and As, but not Hg, that represent a potential health risk. Even at the lowest ingestion rate considered, the majority of households exceeded the risk threshold for Pb, indicating that the concentrations of this metal are of particular concern. To our knowledge, this is the first study to quantify key trace elements in building materials in adobe brick houses and the results indicate that these houses are a potential source of exposure to metals and metalloids in South American mining communities. Additional studies are needed to fully characterize personal exposure and to understand potential adverse health outcomes within the community.
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McEwen, Abigail R, Heileen Hsu-Kim, Nicholas A Robins, Nicole A Hagan, Susan Halabi, Olivo Barras, Daniel deB Richter, John J Vandenberg, et al. (2016). Residential metal contamination and potential health risks of exposure in adobe brick houses in Potosí, Bolivia. The Science of the total environment, 562. pp. 237–246. 10.1016/j.scitotenv.2016.03.152 Retrieved from https://hdl.handle.net/10161/21242.
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Professor Heileen (Helen) Hsu-Kim is an environmental engineer who specializes in environmental aquatic chemistry and geochemistry. Her research tackles problems related to pollutant metals and the biogeochemical processes that alter their distribution in water, soil, and air. The applications of this work include environmental remediation technologies, the impacts of energy production on water resources, global environmental health, and the environmental implications and applications of nanotechnology.
Dr. Hsu-Kim's current research projects are focused on mercury biogeochemistry, the impacts of coal ash disposal on water quality, recovering valuable materials from geological wastes, and health impacts of trace metal/metalloid exposures. A central theme to her work is the utilization of chemical speciation for understanding and predicting the persistence, mobility and bioavailability of metals and minerals in the aquatic environment.
The methodologies her group employs for this research include laboratory techniques for quantifying trace element speciation, functional measures of reactivity and bioavailability of contaminant metals, and techniques to probe interactions at mineral, water and microbial interfaces.
Design and analysis of clinical trials, statistical analysis of biomarker and high dimensional data, development and validation of prognostic and predictive models.
Richter’s research and teaching links soils with ecosystems and the wider environment, most recently Earth scientists’ Critical Zone. He focuses on how humanity is transforming Earth’s soils from natural to human-natural systems, specifically how land-uses alter soil processes and properties on time scales of decades, centuries, and millennia. Richter's book, Understanding Soil Change (Cambridge University Press), co-authored with his former PhD student Daniel Markewitz (Professor at University of Georgia), explores a legacy of soil change across the Southern Piedmont of North America, from the acidic soils of primary hardwood forests that covered the region until 1800, through the marked transformations affected by long-cultivated cotton, to contemporary soils of rapidly growing and intensively managed pine forests. Richter and colleagues work to expand the concept of soil as the full biogeochemical weathering system of the Earth’s crust, ie, the Earth’s belowground Critical Zone, which can be tens of meters deep. The research examines decadal to millennial changes in the chemistry and cycling of soil C, N, P, Ca, K, Mg, and trace elements B, Fe, Mn, Cu, Be, Zr, and Zn across full soil profiles as deep at 30-m. Since 1988, Richter has worked at and directed the Long-Term Calhoun Soil-Ecosystem Experiment (LTSE) in the Piedmont of South Carolina, a collaborative study with the USDA Forest Service that quantifies how soils form as natural bodies and are transformed by human action, and a study that has grown to become an international model for such long-term soil and ecosystem studies. In 2005, Richter and students initiated the first comprehensive international inventory project of the world’s LTSEs, using an advanced-format website that has networked metadata from 250 LTSEs. The LTSEs project has held three workshops at Duke University, NCSU's Center for Environmental Farming Systems, and the USDA Forest Service's Calhoun Experimental Forest and Coweeta Hydrologic Laboratory, hosting representatives from Africa, Asia, Australia, Europe, and the Americas. Richter's 60-year old Long Term Calhoun Soil and Ecosystem Experiment is linked to similar experiments and platforms around the world via the ‘Long-Term Soil-Ecosystem Experiments Global Inventory’, assembled by Dan Richter, Pete Smith, and Mike Hofmockel."He is an active member of the International Commission on Stratigraphy’s Working Group on the Anthropocene. Richter has written in the peer-reviewed literature about all of these projects, and in November 2014 his soils research at the Calhoun and his soils teaching were featured in Science magazine.
Dr. Vandenberg served as Director of the Health and Environmental Effects Assessment Park Division of the Center for Public Health and Environmental Assessment, at the US Environmental Protection Agency (retired, 2021). He has over 35 years of experience in environmental health risk assessment and was responsible for leadership, planning and oversight of EPA’s Integrated Science Assessments for the major (criteria) air pollutants and Integrated Risk Information System (IRIS) assessments for high priority hazardous air pollutants, and for development of new risk assessment methodologies. He has testified to committees of the U.S. House of Representatives and the U.S. Senate on the health and environmental effects of air pollutants and served as National Program Director of EPA’s Human Health Risk Assessment program and Particulate Matter Research program. Dr. Vandenberg has been a consultant to the World Health Organization, represented EPA in scientific meetings in Europe, South America, Asia and the Middle East, and has served on numerous university and State scientific advisory committees. He was elected Fellow of the Society for Risk Analysis and he is recipient of EPA’s Statesmanship and Distinguished Service Awards.
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