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Antonio Gianfagna, Sapienza Università di Roma (Italy)
Giovanni Battista Andreozzi, Sapienza Università di Roma (Italy)
Paolo Ballirano, Sapienza Università di Roma (Italy)
Alessandro Pacella, Sapienza Università di Roma (Italy)
Simona Mazziotti Tagliani, Sapienza Università di Roma (Italy)
Biagio Maria Bruni, Istituto Superiore di Sanità (Italy)
Luigi Paoletti, Istituto Superiore di Sanità (Italy)
Venera Cardile, Università degli Studi di Catania (Italy)
Armanda Pugnaloni, Università Politecnica delle Marche (Italy)
Federica Giantomassi, Università Politecnica delle Marche (Italy)
Jeanine Fournier, Université Pierre et Marie Curie, Paris 6 (France)
Lorenzo Stievano, Université Pierre et Marie Curie, Paris 6 (France)
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Characterization of mineral fibers, particularly fibrous amphiboles, results relevant for environmental and health aspects. Recently, some detailed crystal-chemical works on fibrous tremolite, aimed to a mineralogical-toxicological correlation, were performed.
The present study reports new chemical and structural data on a fibrous tremolite sample came from Calabrian serpentinite rocks of the S. Mango locality (Catanzaro, Italy), where green stone quarries are diffusely present. These data will be useful for correlation with the results obtained by different biological and toxicological expected tests. The chemical composition of the analyzed sample was obtained through EMPA micro-analysis, while Fe3+/Fetot ratio was carried out utilizing Mössbauer spectroscopy. The total iron content (2.98 wt % FeO) was divided in 2.47 wt % FeO e 0.57 wt % Fe2O3, corresponding to 0.30 (Fe2+) and 0.06 (Fe3+) apfu, respectively.
Powder diffraction pattern data were evaluated by Rietveld method. Cell parameters [a = 9,8475(1) A; b = 18,0751(2) A; c = 5,28241(4) A; β = 104.755(1)°; V = 909,23(1) A3], fractional coordinates, and site scattering (s.s.) for M(1), M(2), M(3), and M(4), were refined. The Fe3+ was mainly assigned to the M(1) site, whereas there aren't significant evidences to discriminate the distribution of Fe3+ in the various octahedral sites.
Photoelectron Spectroscopy Analysis (XPS) and surface reactivity in progress allow to determine the surface chemistry of the fibers and to correlate it with the biological activity. The redox reactivity of these fibrous materials is evaluated from the production of hydroxyl radicals (HO.) in an aqueous buffered medium. These radicals are quantitatively detected by Electron Paramagnetic Resonance (EPR), using a spin trapping agent (DMPO).
Some pro-inflammatory cytokines, such as interleukin-1β(IL-1β), interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α), were determined following exposure to tremolite using the human lung epithelial A549 cells. The results, determined by ELISA kits, showed that the exposure to tremolite, compared with those of crocidolite, promote a consistent release of these cytokines. Moreover, scanning and transmission electron microscopy investigations, performed on the same cultured cells, allowed to better evaluate: a) morphological aspects of the superficial fibre-cell interactions; b) cell damage related to mitochondria compromission; c) apoptotic and necrotic cell dead. The MTT test (cell viability) showed decreasing values in treated cultures mostly at 48h, compared to the relative controls.
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