Soil-pH and cement influence the weathering kinetics of chrysotile asbestos in soils and its hydroxyl radical yield

Walter, Martín; Geroldinger, Gerald; Gille, Lars; Kraemer, Stephan M.; Schenkeveld, Walter D. C.

doi:10.1016/j.jhazmat.2021.128068

Cited by 6 publications

(9 citation statements)

References 72 publications

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“…Chrysotile was obtained from a commercial supplier in China (Shijiazhuang Mining IMP&EXP Trade Co). The Shijiazhuang chrysotile asbestos has been extensively characterized, as reported in Walter et al 15 Its Mg, Si, and Mn content was determined by fusion digestion, its Zn and Co content by neutron activation analysis (NAA), and its Fe, Ni, and Cr content by both fusion digestion and NAA, as reported in Walter et al 15 , 66 In Table 1 , the molar Mg/Si ratio of Shijiazhuang chrysotile is close to the stoichiometric value of 1.5. The two major metal substituents in the fibers were Fe (∼20 g kg –1 ) and Al (7.4 g kg –1 ).…”

Section: Experimental Proceduresmentioning

confidence: 99%

“… a Taken from Walter et al (2019), 15 all other data taken from Walter et al (2022). 66 b The remaining Fe is in phase impurities including magnetite. c Bulk metal and Si contents were determined by fusion digestions ( n = 32) and by neutron activation analysis (NAA, n = 2), and the Fe bulk speciation was determined by Mössbauer 57 Fe spectroscopy.…”

Section: Experimental Proceduresmentioning

confidence: 99%

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The Potential Contribution of Hexavalent Chromium to the Carcinogenicity of Chrysotile Asbestos

Walter

Schenkeveld

Tomatis

et al. 2022

Chem. Res. Toxicol.

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Chrysotile asbestos is a carcinogenic mineral that has abundantly been used in industrial and consumer applications. The carcinogenicity of the fibers is partly governed by reactive Fe surface sites that catalyze the generation of highly toxic hydroxyl radicals (HO•) from extracellular hydrogen peroxide (H2O2). Chrysotile also contains Cr, typically in the low mass permille range. In this study, we examined the leaching of Cr from fibers at the physiological lung pH of 7.4 in the presence and absence of H2O2. Furthermore, we investigated the potential of cells from typical asbestos-burdened tissues and cancers to take up Cr leached from chrysotile in PCR expression, immunoblot, and cellular Cr uptake experiments. Finally, the contribution of Cr to fiber-mediated H2O2 decomposition and HO• generation was studied. Chromium readily dissolved from chrysotile fibers in its genotoxic and carcinogenic hexavalent redox state upon oxidation by H2O2. Lung epithelial, mesothelial, lung carcinoma, and mesothelioma cells expressed membrane-bound Cr(VI) transporters and accumulated Cr up to 10-fold relative to the Cr(VI) concentration in the spiked medium. Conversely, anion transporter inhibitors decreased cellular Cr(VI) uptake up to 45-fold. Finally, chromium associated with chrysotile neither decomposed H2O2 nor contributed to fiber-mediated HO• generation. Altogether, our results support the hypothesis that Cr may leach from inhaled chrysotile in its hexavalent state and subsequently accumulate in cells of typically asbestos-burdened tissues, which could contribute to the carcinogenicity of chrysotile fibers. However, unlike Fe, Cr did not significantly contribute to the adverse radical production of chrysotile.

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Section: Experimental Proceduresmentioning

confidence: 99%

Section: Experimental Proceduresmentioning

confidence: 99%

The Potential Contribution of Hexavalent Chromium to the Carcinogenicity of Chrysotile Asbestos

Walter

Schenkeveld

Tomatis

et al. 2022

Chem. Res. Toxicol.

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“… a As previously reported by Walter et al Values in parentheses represent the standard deviations. b Neutron activation analysis. c Remaining Fe is in magnetite impurities. …”

Section: Methodsmentioning

confidence: 81%

“…4 replicates per treatment were analyzed. This method has been frequently applied before ,,,,− and was carried out according to Walter et al The mean signal intensity (specifically the peak-to-peak intensity ( I pp ) at the second lowest G value in the DMPO/HO • quadruplet) of altered fibers (≙ the decreased HO • yield) was expressed as the percentage of the mean I pp of a quadruplicate of pristine fiber replicates, which were included in each measurement session.…”

Section: Methodsmentioning

confidence: 99%

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Redox Cycling of Tetrahedral Iron Drives the Fenton Reactivity of Chrysotile Asbestos

Walter,

Schenkeveld,

Geroldinger

et al. 2023

ACS Earth Space Chem.

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Chrysotile asbestos is a carcinogenic fibrous mineral. Its pathogenicity is partly governed by the ability of Fe on the fiber surface to catalyze the Fenton reduction of H 2 O 2 (which is produced during inflammatory processes) to form the highly toxic hydroxyl radical (HO •). Recently, tetrahedrally coordinated Fe (Fe tet ) in the fibers' Si sheets was identified as the principal Fe species to catalyze this process. However, as only ferric Fe tet (Fe 3+ tet ) substitutes Si tetrahedra in chrysotile, Fe tet needs to redox cycle to ferrous Fe tet (Fe 2+ tet ) to facilitate fibermediated reductions of H 2 O 2 to HO • . This redox cycling has never been experimentally investigated. Here we demonstrate, by consecutive ascorbate and O 2 treatments, that structural Fe tet in exposed Si sheets of chrysotile fibers can redox cycle between Fe 3+ tet and Fe 2+ tet . Reduction, back-oxidation, and rereduction of Fe 3+ tetdid not labilize the exposed Si sheet and, consequently, did not promote fiber dissolution. However, in the presence of H 2 O 2 , prolonged redox cycling of Fe tet increased fiber dissolution, presumably by accelerating Fe tet dissolution and subsequent labilization of the exposed Si sheet. Chrysotile fibers for which the concentration of Fe tet surface sites undergoing redox cycling was lowered through selective Fe removal showed a rebound in Fe 3+ tet surface site concentration and associated Fenton reactivity once Fe 3+ tetdepleted Si sheets were dissolved off from the fiber surfaces. To conclude, our results demonstrate that redox cycling of Fe tet on chrysotile surfaces produces Fe 2+ tet surface sites, which, as the ultimate Fenton reactive iron species on chrysotile, contribute to the fibers' adverse chemical reactivity.

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Oxidative leaching of V-Cr–bearing reducing slag via a Cr(III) induced Fenton-like reaction in concentrated alkaline solutions

Liu

Wang

et al. 2022

Journal of Hazardous Materials

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Soil-pH and cement influence the weathering kinetics of chrysotile asbestos in soils and its hydroxyl radical yield

Cited by 6 publications

References 72 publications

The Potential Contribution of Hexavalent Chromium to the Carcinogenicity of Chrysotile Asbestos

The Potential Contribution of Hexavalent Chromium to the Carcinogenicity of Chrysotile Asbestos

Redox Cycling of Tetrahedral Iron Drives the Fenton Reactivity of Chrysotile Asbestos

Oxidative leaching of V-Cr–bearing reducing slag via a Cr(III) induced Fenton-like reaction in concentrated alkaline solutions

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