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Assessing human bioaccessibility of trace contaminants in size-fractionated red mud, derived precipitates and geopolymeric blocks

Wang, Chunfeng, Zhu, Yanchen, Yao, Dan, Chen, Guanfei, Wang, Lianjun
Frontiers of environmental science & engineering 2017 v.11 no.6 pp. 12
bioavailability, breathing, copper, gastrointestinal system, humans, ingestion, leaching, lead, pH, risk, zinc
The objective of this study was to provide insight into human exposure to trace contaminants bearing red mud, derived precipitates and geopolymeric blocks due to inhalation contact and/or hand-to-mouth ingestion. The in vitro bioaccessibility behavior of trace contaminants was investigated with the PBET (physiologically based extraction test), ALF (artificial lysosomal fluid) and MGS (modified Gamble’ solution) methods. The results showed that total contents of trace contaminants and operation parameters, such as pH and chelating properties of simulated gastrointestinal phases (PBET), played a joint role in controlling the bioaccessibility efficacy for size-fractionated red mud particles. As for airborne particles (<38 μm size fractions), trace contaminants concentrations extracted by MGS was significantly higher than those by ALF. Additionally, higher bioaccessibility (PBET) values of Cu, Pb, Zn, As, V and U were obtained from red mud derived precipitates compared with those of red mud itself. Even though short-term and long-term leaching values of trace contaminants were relatively lower in the prepared geopolymeric blocks, the health risk could be significantly higher due to the more pronounced bioaccessibility characteristics.