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International audience; Asbestos consists in natural minerals crystallized in a specific habit and possessing in particular properties. In the case of Naturally Occurring Asbestos, usual methods applied to the identification of mineral fibers and the determination of their possible asbestiform nature seems not efficient, especially in the case of mineral fibers included in mineral matrix. We present a new in-situ method based on the use of confocal Raman-in-SEM imaging implemented in a Scanning Electron Microscope as an efficient method for in-situ mineralogy. The limitation of conventional methods is discussed. We applied 2D-Raman imaging to the identification of sub-micrometric fibers included in different mineral matrix. We were able to identify actinolite fibers down to 400 nm in diameter, included in feldspar, quartz and/or calcite matrix. Moreover, Confocal Raman allows the collection of 3D data that would provide access to critical information on the morphology of the amphibole fibers in the volume, such as aspect ratio, fibers distribution and amphibole volume fraction. We performed this method on various examples of rocks containing actinolite fibers of mean structural formula is: Na0,04-0,12Mg2,79-3,73Al0,29-0,58K0,01Ca1,79-1,98Mn0,01-0,09Fe 2+ 0,99-1,91Fe 3+ 0,12-0,25Si7,64-7,73O22(OH)2. We demonstrated that coupling confocal Raman imaging and SEM is a new and efficient in-situ method for identification and morphological characterization of amphibole fibers. Highlights New methods are requested for characterizing asbestos fibers in a mineral matrix SEM-Raman imaging is efficient for characterizing mineral fibers in-situ Confocal Raman imaging makes 3D analysis possible 3D analysis provides information on the aspect ratio and volume fraction of asbestos Fibers thinner than 400nm can be identified by confocal Raman in SEM ( = 532 nm)

INTRODUCTION. The town of Biancavilla (Sicily) was included in the National Priorities List of Contaminated Sites due to environmental dispersion of amphibole fibers owing to the extraction of materials from a local quarry. The present report summarizes results from several, hitherto unpublished, environmental surveys carried out in the area, as well as from published analyses of the chemistry and composition of fibers. METHODS. Data included here comprises environmental fiber concentrations by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) analysis in soil, indoor and outdoor air, personal monitoring, as well as a chemical characterization of the fibers. The full chemical structure and spectroscopic characterization of fibers were obtained through a multi-analytical approach: SEM-EDS, X-ray powder diffraction (XRPD), as well as Mössbauer (MS) and Fourier transform infrared (FT-IR) spectroscopies. RESULTS. Data analyzed provided a spatial and temporal picture of fiber concentrations in Biancavilla, and a qualitative assessment of population exposure. Results suggest that until 2000, the population had been exposed to high levels of amphibole fibers. Mitigation measures adopted since 2001, gradually reduced exposure levels to about 0.10.4 ff/l. Previous studies on fibrous amphiboles from Biancavilla reported considerable chemical variability. Differences in composition, especially concerning the presence of Si, Ca, Fe, and Na, were found both within and between samples. Compared to the previously investigated prismatic fluoro-edenite, these fibrous fluorine amphiboles consistently showed higher average values of Si and Fe content, whereas Ca was significantly lower, which we consider a distinctive characteristic of the fluorine fibrous variety. CONCLUSIONS. The population of Biancavilla had been highly exposed to a suite of fibrous amphiboles for over 50 years. Dust mitigation measures have gradually reduced exposure, but continuous environmental follow-up is necessary in order to monitor exposure levels and prevent adverse health effects for future generations.

International audience; Three fibrous amphiboles that are not regulated as asbestos--two from Biancavilla (Sicily, Italy) and one from Libby (MT, USA)--were studied in order to establish relationships between surface chemistry and surface reactivity. The three fibrous samples, plus one prismatic fluoro-edenite from Biancavilla that was used for comparison, were investigated by X-ray photoelectron spectroscopy (XPS) in order to obtain their quantitative surface compositions and to determine the chemical environment of the Fe in each case. In particular, the Fe 2p(3/2) peak was fitted and, for the first for these materials, the binding energies of Fe(II) oxide, Fe(III) oxide and Fe(III) oxyhydroxide were identified. Bulk chemistries and Fe oxidation states were obtained from previous studies for the samples from Biancavilla, and were investigated in the present work by electron microprobe (EMP) and (57)Fe Mössbauer spectroscopy (MS) for the sample from Libby. Comparison between surface and bulk data revealed that the sample with the lowest bulk Fe oxidation state was the one most affected by surface oxidation, while the samples with bulk highly-oxidised Fe were showing very high signal of Fe (III) oxy-hydroxide probably due to weathering. The surface reactivities of the fibrous amphiboles were investigated by measuring the production of the [DMPO, HO]* radical adduct using electron paramagnetic resonance (EPR) spectroscopy. Notably, significant chemical reactivity was observed; it was found to be comparable with--or, for the Libby sample, even higher than--that of fibrous tremolite (one of the six asbestos minerals). A positive linear correlation was observed when the production of HO* radical was plotted versus the Fe(II) content on the fibre surface. Data on fibrous tremolite obtained from previous studies were added to substantiate the correlation. These results provide evidence that Fe(II) at the fibre surface controls the production of radicals at the fibre surface. The observed relationship provides further confirmation that Fe topochemistry is strictly related to--though not solely responsible for--the toxicity of asbestos and other fibrous amphiboles that are not regulated as asbestos.

The mechanism through which asbestos amphiboles may give rise to mesothelioma is still not completely understood. Several factors have been taken into account, and these include the morphological aspect of the fiber, the chemical composition, and a variety of surface properties which are ultimately responsible for the mineral-cellule interactions[1]. Studies in vitro demonstrate that the morphology of the fiber has a strong role in determining its biological danger, because very thin and long crystallites are hardly eliminated by the alveolar macrophages. However, recent studied show that lung injury after asbestos exposure is associated with an oxidative stress that is catalyzed by iron in the fiber[2]. It follows that the rapid determination of the chemical composition of asbestiform amphiboles, and of its Mg/Fe ratio in particular, is extremely important in environmental studies. The direct analysis can be achieved only by micro-chemical tools such as by EDS- or WDS-equipped electron microscopes. However, these techniques are extremely expensive and often unsuitable when dealing with extremely fibrous (diameter < 3 µm) materials. Therefore a rapid and easily accessible method is highly desirable in large scale environmental monitoring. The best alternative to EMPA is provided by FTIR spectroscopy, a technique which can be used on both single crystals (down to few µm in dimension) and powders. Here we present the results of a new calibration based on the analysis of a large set of well-characterized fibrous and prismatic natural amphiboles spanning a very large variety of chemical compositions and geological occurrences. All samples were previously studied using X-ray diffraction and EMPA. FTIR spectra in the principal OH-stretching region were collected on KBr disks prepared with a mineral:matrix = 5:150 mg ratio. Most spectra show four prominent bands which can be assigned to the combination of Mg and F2+ at the OH-coordinated M(1,3) sites[3,4,5,6]. The digitized spectra were fitted by interactive optimization followed by least-squares refinement; all bands were modelled as symmetric Gaussians. [3,4] showed that the binary site-occupancies at M(1) and M(3) in the amphibole structure are related to the observed intensities of the four (A to D) components in the principal IR OH-stretching spectrum. Using the original equations of [7]: M(1,3)Mg = 3IA + 2IB + IC and M(1,3)M2+ = IB + 2IC + 3ID (with M2+ = Fe2+) where IA-ID are the intensities measured for the corresponding A to D bands, one can derive the (Mg, M2+) site populations at M(1,3) with a high degree of confidence. This method is particularly suitable for asbestiform materials which cannot be properly characterized by EMP. The present work shows that the above spectroscopic tool can be applied to a large variety of amphibole types. For species were significant (Mg, Fe) are present at M(4) (i.e. anthophyllite–cummingtonite–grunerite) an additional information (e.g. Mössbauer) is however required for a complete characterization of the sample. [1] van Oss, C.J., Naim, J.O., Costanza, P.M., Giese, R.F. Jr., Wu, W., Sorling, A.F. (1999) Clays and Clay Minerals, 47, 697-707. [2] Xinchao, W., Wu, Y., Stonehuerner, J.G., Dailey, L.A., Richards, J.D., Jaspers, I., Piantadosi, C.A., Ghio, A.J. (2006) Am. J. Respir. Cell. Mol. Biol., 34, 286–292. [3] Della Ventura, G., Robert, J.-L., Hawthorne, F.C. (1996) Geochimica and Cosmochimica Acta, vol. spec. 5, 55-63. [4] Della Ventura, G., Robert, J.-L., Raudsepp, M., Hawthorne, F.C., Welch, M. (1997) American Mineralogist, 82, 291-301. [5] Iezzi, G., Della Ventura, G., Hawthorne, F.C., Pedrazzi, G., Robert, J.-L., Novembre, D. (2005) European Journal of Mineralogy, 17, 733-740. [6] Iezzi, G., Della Ventura, G., Bellatreccia, F., Lo Mastro, S., Gunther, M., Bandly, (2007) Mineralogical Magazine, in press. [7] Burns, R.G. and Strens, R.G.J. (1966) Science, 153, 890-892.

BACKGROUND. The inhalation of fibrous amphiboles can result in pulmonary fibrosis, lung cancer and mesothelioma. Although these fibres have the same disease-causing potential, their different morphologies and chemical composition can determine different biological activities. An unusual cluster of mesothelioma was evidenced in Biancavilla (Sicily) where no inhabitant had been significantly exposed to asbestos. OBJECTIVE. We herein discuss the mechanism of action of amphiboles, focusing on the fibres identified in the study area. RESULTS. Human lung carcinoma cells have been exposed to two different materials: prismatic fluoro-edenite and fibres with fluoro-edenitic composition. Only in the second case, they exhibit features typical of transformed cells, such as multinucleation, prosurvival activity and pro-inflammatory cytokine release. Accordingly, in vivo studies demonstrated that the fibrous sample only could induce a mesotheliomatogenic effect. Conclusions. Fibres with fluoro-edenitic composition behave similarly to the asbestos crocidolite, whose connection with inflammation and lung cancer is well established.