title: The chemical environment of iron in mineral fibres. A combined X-ray absorption and Mössbauer spectroscopic study.
abstract: Although asbestos represents today one of the most harmful contaminant on Earth, in 72% of the countries worldwide only amphiboles are banned while controlled use of chrysotile is allowed. Uncertainty on the potential toxicity of chrysotile is due to the fact that the mechanisms by which mineral fibres induces cyto- and geno-toxic damage are still unclear. We have recently started a long term project aimed at the systematic investigation of the crystal-chemistry, bio-interaction and toxicity of the mineral fibres. This work presents a systematic structural investigation of iron in asbestos and erionite (considered the most relevant mineral fibres of social and/or economic-industrial importance) using synchrotron X-ray absorption and Mössbauer spectroscopy. In all investigated mineral fibres, iron in the bulk structure is found in octahedral sites and can be made available at the surface via fibre dissolution. We postulate that the amount of hydroxyl radicals released by the fibers depends, among other factors, upon their dissolution rate; in relation to this, a ranking of ability of asbestos fibres to generate hydroxyl radicals, resulting from available surface iron, is advanced: amosite > crocidolite ≈ chrysotile > anthophyllite > tremolite. Erionite, with a fairly high toxicity potential, contains only octahedrally coordinated Fe(3+). Although it needs further experimental evidence, such available surface iron may be present as oxide nanoparticles coating and can be a direct cause of generation of hydroxyl radicals when such coating dissolves.
authors.affiliation: Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Via S. Eufemia 19, I-41121 Modena, Italy. Electronic address: simone.pollastri@unimore.it.
authors.forename: Simone
authors.initials: S
authors.lastname: Pollastri
authors.affiliation: CNR-IOM-OGG c/o ESRF, GILDA CRG, 71 Rue des Martyrs, F-38000 Grenoble, France.
authors.forename: Francesco
authors.initials: F
authors.lastname: D'Acapito
authors.affiliation: CNR-IOM-OGG c/o ESRF, GILDA CRG, 71 Rue des Martyrs, F-38000 Grenoble, France.
authors.forename: Angela
authors.initials: A
authors.lastname: Trapananti
authors.affiliation: Department of Physics, University of Rome "Tor Vergata", Via della ricerca scientifica 1, I-00133 Roma, Italy.
authors.forename: Ivan
authors.initials: I
authors.lastname: Colantoni
authors.affiliation: Department of Earth Sciences, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Roma, Italy.
authors.forename: Giovanni B
authors.initials: GB
authors.lastname: Andreozzi
authors.affiliation: Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Via S. Eufemia 19, I-41121 Modena, Italy.
authors.forename: Alessandro F
authors.initials: AF
authors.lastname: Gualtieri
mesh_terms: D001194:Asbestos / Q000737:chemistry / Q000633:toxicity; D005290:Ferric Compounds / Q000737:chemistry / Q000633:toxicity; D017665:Hydroxyl Radical / Q000032:analysis; D007202:Indicators and Reagents; D007501:Iron / Q000737:chemistry*; D019016:Mineral Fibers / Q000633:toxicity*; D012015:Reference Standards; D012995:Solubility; D015204:Spectroscopy, Mossbauer; D014961:X-Ray Diffraction; D017641:Zeolites / Q000737:chemistry / Q000633:toxicity
chemical_list: D005290:Ferric Compounds; D007202:Indicators and Reagents; D019016:Mineral Fibers; C083174:erionite; D017641:Zeolites; D001194:Asbestos; C000499:ferric oxide; D017665:Hydroxyl Radical; D007501:Iron
keywords: Asbestos; Chemical environment; Iron; Mineral fibres; Toxicity