Oral bioaccessibility of metal(loid)s in dust materials from mining areas of northern Namibia
Language English Country Netherlands Media print-electronic
Document type Journal Article, Research Support, Non-U.S. Gov't
PubMed
30654327
DOI
10.1016/j.envint.2018.12.027
PII: S0160-4120(18)32356-0
Knihovny.cz E-resources
- Keywords
- Bioacessibility, Dust mineralogy, Metal(loid)s, Mining, Namibia, Smelting,
- MeSH
- Arsenates MeSH
- Child MeSH
- Adult MeSH
- Mining * MeSH
- Metals * administration & dosage analysis MeSH
- Soil Pollutants * administration & dosage analysis MeSH
- Humans MeSH
- Environmental Monitoring MeSH
- Dust * analysis MeSH
- Environmental Exposure * MeSH
- Check Tag
- Child MeSH
- Adult MeSH
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Namibia MeSH
- Names of Substances
- Arsenates MeSH
- Metals * MeSH
- Soil Pollutants * MeSH
- Dust * MeSH
Ore mining and processing in semi-arid areas is responsible for the generation of metal(loid)-containing dust, which is easily transported by wind to the surrounding environment. To assess the human exposure to dust-derived metal(loid)s (As, Cd, Cu, Pb, Sb, Zn), as well as the potential risks related to incidental dust ingestion, we studied mine tailing dust (n = 8), slag dust (n = 5) and smelter dust (n = 4) from old mining and smelting sites in northern Namibia (Kombat, Berg Aukas, Tsumeb). In vitro bioaccessibility testing using extraction in simulated gastric fluid (SGF) was combined with determination of grain-size distributions, chemical and mineralogical characterizations and leaching tests conducted on original dust samples and separated PM10 fractions. The bulk and bioaccessible concentrations of the metal(loid)s were ranked as follows: mine tailing dusts < slag dusts ≪ smelter dusts. Extremely high As and Pb bioaccessibilities in the smelter dusts were caused by the presence of highly soluble phases such as arsenolite (As2O3) and various metal-arsenates unstable under the acidic conditions of SGF. The exposure estimates calculated for an adult person of 70 kg at a dust ingestion rate of 50 mg/day indicated that As, Pb (and also Cd to a lesser extent) grossly exceeded tolerable daily intake limits for these contaminants in the case of slag and smelter dusts. The high risk for smelter dusts has been acknowledged, and the safety measures currently adopted by the smelter operator in Tsumeb are necessary to reduce the staff's exposure to contaminated dust. The exposure risk for the local population is only important at the unfenced disposal sites at Berg Aukas, where the PM10 exhibited high levels of bioaccessible Pb.
Czech Geological Survey Geologická 6 152 00 Prague 5 Czech Republic
Department of Geology Faculty of Science University of Namibia Private Bag 13301 Windhoek Namibia
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