Elena Belluso

Assessment of the use of Raman spectroscopy for the determination of amphibole asbestos

Abstract Raman spectroscopy was assessed for its ability to rapidly identify asbestos phases by submitting the amphiboles anthophyllite, amosite, crocidolite and tremolite to spectroscopic analysis. All the phases were characterized by using XRD, SEM, TEM (CTEM, SAED), AEM and EDS techniques. This study demonstrates that accurate identification of the mineralogical phase can be attained by analysing the position in the Raman spectrum of the bands corresponding to the symmetric stretching modes (vs) and to the antisymmetric stretching modes (vas) of the different Si-O linkages. Raman spectroscopy thus proves to be an effective technique for rapidly distinguishing the different fibrous minerals examined.

Chemical, dimensional and morphological ultrafine particle characterization from a Waste-to-Energy plant

Waste combustion processes are responsible of particles and gaseous emissions. Referring to the particle emission, in the last years specific attention was paid to ultrafine particles (UFPs, diameter less than 0.1 μm), mainly emitted by combustion processes. In fact, recent findings of toxicological and epidemiological studies indicate that fine and ultrafine particles could represent a risk for health and environment. Therefore, it is necessary to quantify particle emissions from incinerators also to perform an exposure assessment for the human populations living in their surrounding areas. To these purposes, in the present work an experimental campaign aimed to monitor UFPs was carried out at the incineration plant in San Vittore del Lazio (Italy). Particle size distributions and total concentrations were measured both at the stack and before the fabric filter inlet in order to evaluate the removal efficiency of the filter in terms of UFPs. A chemical characterization of UFPs in terms of heavy metal concentration was performed through a nuclear method, i.e., Instrumental Neutron Activation Analysis (INAA), as well as a mineralogical investigation was carried out through a Transmission Electron Microscope (TEM) equipped with an Energy Dispersive Spectrometer (EDS) in order to evaluate shape, crystalline state and mineral compound of sampled particles. Maximum values of 2.7 × 10(7) part. cm(-3) and 2.0 × 10(3) part. cm(-3) were found, respectively, for number concentration before and after the fabric filter showing a very high efficiency in particle removing by the fabric filter. With regard to heavy metal concentrations, the elements with higher boiling temperature present higher concentrations at lower diameters showing a not complete evaporation in the combustion section and the consequent condensation of semi-volatile compounds on solid nuclei. In terms of mineralogical and morphological analysis, the most abundant compounds found in samples collected before the fabric filter are Na-K-Pb oxides followed by phyllosilicates, otherwise, different oxides of comparable abundance were detected in the samples collected at the stack.

Asbestos and other fibrous minerals contained in the serpentinites of the Gimigliano-Mount Reventino Unit (Calabria, S-Italy)

Serpentinites are metamorphic rocks with good technological properties and valuable ornamental characteristics, which have been exploited since ancient times. Actually, their use is limited and monitored in several countries worldwide because they can contain fibrous asbestos minerals that may be carcinogenic. Furthermore, certain types of fibrous minerals can be confused with asbestos, and must therefore be carefully investigated. We have investigated the possible presence of the asbestos and non-asbestos fibrous phases contained in serpentinitic rocks in a meta-ophiolitic sequence from the Gimigliano-Mount Reventino Unit (Southern Italy), which had not been previously assessed. The detection and quantification of asbestos and the correct distinction of the fibrous non-asbestos minerals are very important not only from a scientific point of view, but also from a legislative one. This is especially the case for the administrative agencies that have to take decisions with regards to the implementation of public and occupational health protection measures (e.g., in road yards and quarry excavations). As a consequence of this, serpentinitic rock samples have been characterized in detail through X-ray powder diffraction, scanning and transmission electron microscopy combined with energy-dispersive spectrometry, analytical electron microscopy (SEM–EDS and TEM–AEM), differential scanning calorimetry, thermogravimetry and micro-Raman spectroscopy. Two kinds of asbestos and four kinds of non-asbestos fibrous silicates have been detected in the examined samples. In order of decreasing abundance these are polygonal serpentine, chrysotile, fibrous antigorite, tremolite, gedrite and magnesiohornblende. The size, morphology, crystallinity and chemical composition of the fibres were also discussed, in the light of the possible role these properties could play in the carcinogenic effect on human health.

Effects of asbestiform antigorite on human alveolar epithelial A549 cells: A morphological and immunohistochemical study

The purpose of the study was to investigate the biological risk of asbestiform antigorite, which is a fibrous variety of antigorite, one of the natural mineral fibres of the serpentine group to which asbestos chrysotile belongs. Asbestiform antigorite is very abundant and commonly found associated with asbestos chrysotile in serpentinites, a kind of rock outcropping present in many geographical locations worldwide. In this study we evaluated the morphological, immunohistochemical and functional effects of antigorite fibres in alveolar epithelial cancer cells (A549), a standardized human cell line currently used as a model to study cytotoxicity induced by pharmacological agents. The antigorite fibres were identified and characterized morphologically and chemically by X-ray powder diffractometry, transmission and scanning electron microscopy, both with annexed energy dispersive spectrometry. The effects of 50 microg/ml of antigorite in A549 lung cells treated at 24 and 48 h resulted in increased synthesis of VEGF, Cdc42 and beta-catenin that represent potential risks for cancer development. Phalloidin labelling showed an irregular distribution of filamentous actin resulting from antigorite contact. Our studies indicate potential cellular toxicity of antigorite in vivo, providing the opportunity to elucidate the effect of asbestos on cancer induction and possible modes of therapy.

Synthesis and characterization of tremolite asbestos fibres

Fibres of Fe-free tremolitic amphibole were synthesized using hydrothermal conditions. The run products contained only minor amounts of one other phase, quartz, as determined by X-ray powder diffraction (XRPD). The fibrous material was characterized by scanning and transmission electron microscopies combined with energy dispersive spectrometry (SEM-EDS and TEM-EDS), differential scanning calorimetry (DSC), thermogravimetry (TG) and micro-Raman spectroscopy. The average length and width of the fibres, as determined by SEM and TEM on about 600 fibrils, fall within the definition of breathable fibres and potentially carcinogenic. Electron diffraction patterns of selected areas (SAED) from single fibres revealed a high crystallinity. Raman spectroscopy showed bands matching those observed on natural samples of tremolite. These synthetic and well-characterized fibres can be used in in vitro studies, where cell reactions to synthetic and natural tremolite fibres are compared.

Cytotoxicity induced by exposure to natural and synthetic tremolite asbestos: an in vitro pilot study.

Mineral fibers are potential carcinogens to humans. In order to help clarify the etiology of the pathological effects of asbestos, cellular reactions to natural and synthetic asbestos fibers were compared using a lung alveolar cancer cell line (A549 epithelial cells), considered the first target of inhaled micro-environmental contaminants. Natural asbestos tremolite (NAT) fibers were collected from rocks in NW Italy. Synthetic asbestos tremolite (SAT) was iron-free and therefore considered as standard tremolite. Both fibers, subjected to mineralogical characterization by X-ray powder diffractometry, electron microscopy and energy dispersive spectrometry, fell within the definition of respirable and potentially carcinogenic fibers. Several signs of functional and structural cell damage were found after treatment with both fibers, documented by viability, motility, and morphological perturbations. Phalloidin labeling showed irregular distribution of cytoskeletal F-actin, whereas immunohistochemical investigations showed abnormal expression of VEGF, Cdc42, β-catenin, assessed as risks indicators for cancer development. Both fibers caused significant loss of viability, even compared to UICC crocidolite, but, while SAT fibers exerted a more direct cytotoxic effect, survival of damaged cells expressing high VEGF levels was detected after NAT contact. This in vitro pilot study outlines potential health risks of NAT fibers in vivo related to their iron content, which could trigger signaling networks connected with cell proliferation and neoplastic transformation.

Kinetics of the Decomposition of Crocidolite Asbestos: A Preliminary Real-Time X-Ray Powder Diffraction Study

This work is a preliminary kinetic study of the crocidolite decomposition followed in situ at high temperature using real time conventional powder diffraction and DTA in the temperature range 720-795 °C. The data analysis using the Avrami models indicates that the rate limiting step of the reaction is monodimensional ion diffusion (n=0.5) with an activation energy of 129 (10)kcal/mole.

New insights on the biomineralisation process developing in human lungs around inhaled asbestos fibres

Once penetrated into the lungs of exposed people, asbestos induces an in vivo biomineralisation process that leads to the formation of a ferruginous coating embedding the fibres. The ensemble of the fibre and the coating is referred to as asbestos body and is believed to be responsible for the high toxicological outcome of asbestos. Lung tissue of two individuals subjected to prolonged occupational exposure to crocidolite asbestos was investigated using synchrotron radiation micro-probe tools. The distribution of K and of elements heavier than Fe (Zn, Cu, As, and Ba) in the asbestos bodies was observed for the first time. Elemental quantification, also reported for the first time, confirmed that the coating is highly enriched in Fe (~20% w/w), and x-ray absorption spectroscopy indicated that Fe is in the 3+ oxidation state and that it is present in the form of ferritin or hemosiderin. Comparison of the results obtained studying the asbestos bodies upon removing the biological tissue by chemical digestion and those embedded in histological sections, allowed unambiguously distinguishing the composition of the asbestos bodies, and understanding to what extent the digestion procedure altered their chemical composition. A speculative model is proposed to explain the observed distribution of Fe.

Trace elements in hazardous mineral fibres.

Both occupational and environmental exposure to asbestos-mineral fibres can be associated with lung diseases. The pathogenic effects are related to the dimension, biopersistence and chemical composition of the fibres. In addition to the major mineral elements, mineral fibres contain trace elements and their content may play a role in fibre toxicity. To shed light on the role of trace elements in asbestos carcinogenesis, knowledge on their concentration in asbestos-mineral fibres is mandatory. It is possible that trace elements play a synergetic factor in the pathogenesis of diseases caused by the inhalation of mineral fibres. In this paper, the concentration levels of trace elements from three chrysotile samples, four amphibole asbestos samples (UICC amosite, UICC anthophyllite, UICC crocidolite and tremolite) and fibrous erionite from Jersey, Nevada (USA) were determined using inductively coupled plasma mass spectrometry (ICP-MS). For all samples, the following trace elements were measured: Li, Be, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, As, Rb, Sr, Y, Sb, Cs, Ba, La, Pb, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, U. Their distribution in the various mineral species is thoroughly discussed. The obtained results indicate that the amount of trace metals such as Mn, Cr, Co, Ni, Cu and Zn is higher in anthophyllite and chrysotile samples, whereas the amount of rare earth elements (REE) is higher in erionite and tremolite samples. The results of this work can be useful to the pathologists and biochemists who use asbestos minerals and fibrous erionite in-vitro studies as positive cyto- and geno-toxic standard references.

Asbestiform Minerals Associated with Chrysotile from the Western Alps (Piedmont - Italy): Chemical Characteristics and Possible Related Toxicity

Two new asbestiform minerals, balangeroite (Balangero, Italy) and carlosturanite (Val Varaita, Italy), have been investigated from the standpoint of their potential toxicity. Their characteristics have been compared with chrysotile and antigorite with which they are always associated. EPR spectra of the minerals revealed the presence of paramagnetic ions, including Fe3+ and Mn2+, in different crystal configurations. The presence of Fe2+ was shown by the enhancement of the Fe3+ signals after grinding in air. Balangeroite is the richer in both Fe2+ and Fe3+ which are in magnetic interaction with each other, unlike antigorite, in which only isolated and weakly interactive ions are present. Profound modifications of the structures are found upon standing in solutions mimicking the biological environment. This suggests that these minerals may interact in a number of ways in vivo Taking into account both their form and chemical composition they may be regarded as potentially carcinogenic components of fibrous minerals extracted from the Piedmont mines.