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Residential metal contamination and potential health risks of exposure in adobe brick houses in Potosí, Bolivia
Citation:
McEwen, A., H. Hsu-Kim, N. Robins, N. Hagan, S. Halabi, O. Barras, D. Richter, AND J. Vandenberg. Residential metal contamination and potential health risks of exposure in adobe brick houses in Potosí, Bolivia. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, Netherlands, 562:237-246, (2016).
Impact/Purpose:
To our knowledge, this is the first study to quantify key trace elements in building materials in adobe brick houses. The results show that the building materials in these houses are a source of exposure to potentially toxic trace elements in South American mining communities. The more detailed information on the bioaccessible fraction of elements in the homes indicates that Pb is a primary element of concern for human health, particularly for children through incidental ingestion. As is also a concern, particularly if ingestion rates exceed a value assumed in US based risk assessments (100 mg-day). Additional environmental sampling, biomonitoring, and exposure questionnaires are needed to fully characterize sources of exposure and to understand potential adverse health outcomes within the community.
Description:
Potosí, Bolivia, is the site of centuries of historic and present-day mining of the Cerro Rico Mountain, known for its rich polymetallic deposits, and was the site of large-scale Colonial era silver refining operations, both of which have left a legacy of pollution. In this study, trace elements were quantified in adobe brick, dirt floor, and surface dust samples from 49 houses. Mean concentrations of total mercury (Hg), lead (Pb), and arsenic (As) were statistically significantly greater than concentrations measured in Sucre, Bolivia, a non-mining town used as a reference site, and exceeded US-based soil screening levels that are designed to be protective of human health. Adobe brick samples were analyzed for bioaccessible concentrations of elements using a simulated gastric fluid (GF) extraction. Mean GF extractable concentrations of Hg, As, and Pb were 0.841, 14.9, and 30.2 percent of the total concentration, respectively. Total and GF extractable concentrations of these elements 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 (50-1000 mg/day). Although the majority of households have total Hg, As, and Pb concentrations that represent a potential health risk, fewer are of concern when GF extractable concentrations are considered at lower ingestion rates. For Hg, only a small percentage of the sampled houses have GF extractable Hg concentrations that represent a potential health risk, even at the highest ingestion rate considered. For As, under situations where the ingestion rate is approximately 150-200 mg/day or greater, the majority of households have GF extractable As concentrations that represent a potential health risk. In contrast, even at the lowest ingestion rate considered, the majority of households have total and GF extractable Pb concentrations in adobe bricks that represent a potential health risk to children.
