Distinguishing asbestos cement from fiber-reinforced cement through portable µ-Raman spectroscopy and portable X-ray fluorescence.

It is now widely acknowledged that asbestos can adversely affect human health; accordingly, in recent decades, fiber-reinforced cement (FRC) has been used as a substitute for asbestos cement (AC). This manuscript focuses on portable micro-Raman spectroscopy coupled with portable microscopy (p-µR) and portable X-ray fluorescence (p-XRF) as a means to identify chrysotile fibers in AC (Eternit) and fibers present in the asbestos-free FRC used as a substitute. Our results show that the simultaneous use of portable devices such as p-µR and p-XRF may be useful in quickly identifying fibrous chrysotile asbestos in Eternit, as well as polyvinyl fibers in new material FRC used as substitutes for Eternit. Chrysotile shows bands in the 800-200 cm-1 range, whereas polyvinyl alcohol fibers show bands in the 3000-800 cm-1 range. The p-XRF data on the two types of cement could possibly be used as a chemical fingerprint for the two different materials. Given that exposure to asbestos is a serious health hazard, its rapid and reliable detection in situ on residential buildings is important both for citizens and for administrative bodies charged with safeguarding public health. We believe that our study provides valuable insight into the potential use of portable devices for identifying asbestos and asbestos-free materials.

Natural occurrence of asbestos in serpentinite quarries from Southern Spain.

The nevado-filábride complex (NFC) (southern Spain) is well known for its widespread mining and quarrying activities. Serpentinite and metabasite rocks are extracted, processed and traded as building and ornamental stones. Due to the possible presence of natural occurrence of asbestos (NOA) in these rocks, the aim of this paper is to conduct an in-depth characterisation of fibrous minerals. To this aim, seven serpentinite rock samples were collected in four quarries located in the Sierra Nevada and Sierra de los Filabres (South-eastern Spain), which were then analysed by X-ray powder diffraction (XRPD), scanning electron microscopy combined with energy-dispersive spectrometry (SEM/EDS), differential scanning calorimetry (DSC), derivative thermogravimetry (DTG) and X-ray synchrotron microtomography (SR-µCT). It is essential to investigate asbestos minerals from both scientific and legal perspective, especially for public health officials that implement occupational health and safety policies, in order to safeguard the health of workers (e.g. quarry excavations, road yards, civil constructions, building stones).

Synthesis of Ni-Doped Tremolite Fibers to Help Clarify the Aetiology of the Cytotoxic Outcome of Asbestos.

Asbestos fibers act as complex crystal-chemical reservoirs susceptible of releasing potentially toxic elements (such as ions impurities) into the lung cellular environment during permanency and dissolution. To comprehend the exact pathological mechanisms that are triggered upon inhalation of asbestos fibers, in vitro studies on possible interactions between the mineral and the biological system have been carried out mostly by using natural asbestos. However, this latter comprises intrinsic impurities such as Fe2+/Fe3+ and Ni2+ ions, and other eventual traces of metallic pathogens. Furthermore, often, natural asbestos is characterized by the co-presence of several mineral phases, fiber dimensions of which are randomly distributed in width and in length. For these reasons, it is albeit challenging to precisely identify toxicity factors and to define the accurate role of each factor in the overall pathogenesis of asbestos. In this regard, the availability of synthetic asbestos fibers with accurate chemical composition and specific dimensions for in vitro screening tests would represent the perfect tool to correlate asbestos toxicity to its chemico-physical features. Herein, to palliate such drawbacks of natural asbestos, well-defined Ni-doped tremolite fibers were chemically synthesized in order to offer biologists adequate samples for testing the specific role of Ni2+ in asbestos toxicity. The experimental conditions (temperature, pressure, reaction time and water amount) were optimized to produce batches of asbestos fibers of the tremolite phase, with uniformly distributed shape and dimensions and a controlled content of Ni2+ metal ions.

Dissolution Reaction and Surface Modification of UICC Amosite in Mimicked Gamble's Solution: A Step towards Filling the Gap between Asbestos Toxicity and Its Crystal Chemical Features.

This study focuses on the dissolution process and surface characterization of amosite fibres following interaction with a mimicked Gamble's solution at a pH of 4.5 and T = 37 °C, up to 720 h. To achieve this, a multi-analytical approach was adopted, and the results were compared to those previously obtained on a sample of asbestos tremolite and UICC crocidolite, which were investigated under the same experimental conditions. Combining surface chemical data obtained by XPS with cation release quantified by ICP-OES, an incongruent behaviour of the fibre dissolution was highlighted for amosite fibres, similarly to asbestos tremolite and UICC crocidolite. In particular, a preferential release of Mg and Ca from the amphibole structure was observed, in agreement with their Madelung site energies. Notably, no Fe release from amosite fibres was detected in our experimental conditions (pH of 4.5 and atmospheric pO2), despite the occurrence of Fe(II) at the M(4) site of the amphibole structure, where cations are expected to be rapidly leached out during mineral dissolution. Moreover, the oxidation of both the Fe centres initially present on the fibre surface and those promoted from the bulk, because of the erosion of the outmost layers, was observed. Since biodurability (i.e., the resistance to dissolution) is one of the most important toxicity parameters, the knowledge of the surface alteration of asbestos possibly occurring in vivo may help to understand the mechanisms at the basis of its long-term toxicity.

X-ray synchrotron microtomography: a new technique for characterizing chrysotile asbestos.

Over the last decades, many studies have been conducted on rocks containing Naturally Occurring Asbestos (NOA) to determine the potential health risks to exposed neighboring populations. It is difficult to accurately characterize the asbestos fibres contained within the rocks as conventional techniques are not effective and have drawbacks associated with the disturbance of the sample under study. X-ray synchrotron microtomography (SR-µCT) supplemented with polarized light microscope (PLM), scanning electron microscopy analysis combined with energy dispersive spectrometry (SEM/EDS), electron probe micro-analysis (EPMA) were used for identifying asbestos fibres in a mineral matrix. As a case study, we analyzed a representative set of veins and fibrous chrysotile that fills the veins, taken from massive serpentinite outcrops (Southern-Italy). We were able to identify respirable chrysotile fibres (regulated asbestos) within the serpentinite matrix. SR-µCT of NOA veins achieved the resolution and reconstructed 3D structures of infill chrysotile asbestos fibres and other phase structures that were not resolvable with PLM, SEM or EPMA. Moreover, due to differences in chemical composition between veins and matrix, the data obtained enabled us to evaluate the vein shapes present in the massive serpentinite matrix. In particular, iron and aluminum distribution variations between veins and matrix induce different radiation absorption patterns thus permitting a detailed image-based 3D geometric reconstruction. The advantages of the SR-µCT technique as well as limitation of conventional methods are also discussed. These analytical approaches will be used for conducting future research on NOA of other minerals, which exhibit asbestiform and non-asbestiform habits within veins, including asbestos amphiboles.

Thermal inertization of amphibole asbestos modulates Fe topochemistry and surface reactivity.

This study discloses the morphological and chemical-structural modifications that occur during thermal degradation of amphibole asbestos. Low-iron tremolite and iron-rich crocidolite were heated at temperatures ranging from r.t. to 1200 °C. Heating promoted a complex sequence of iron oxidation, migration and/or clustering and, finally, the formation of brittle fibrous pseudomorphs consisting of newly formed minerals and amorphous nanophases. The effects of the thermal modifications on toxicologically relevant asbestos reactivity were evaluated by quantifying carbon- and oxygen-centred, namely hydroxyl (OH), radicals. Heating did not alter carbon radicals, but largely affected oxygen-centred radical yields. At low temperature, reactivity of both amphiboles decreased. At 1200 °C, tremolite structural breakdown was achieved and the reactivity was further reduced by migration of reactive iron ions into the more stable TO4 tetrahedra of the newly formed pyroxene(s). Differently, crocidolite breakdown at 1000 °C induced the formation of hematite, Fe-rich pyroxene, cristobalite, and abundant amorphous material and restored radical reactivity. Our finding suggests that thermally treated asbestos and its breakdown products still share some toxicologically relevant properties with pristine fibre. Asbestos inertization studies should consider morphology and surface reactivity, beyond crystallinity, when proving that a thermally inactivated asbestos-containing material is safe.

Order-disorder character and twinning in the structure of a new synthetic titanosilicate: (Ba,Sr)4Ti6Si4O24 x H2O.

Prismatic crystals of the title compound, up to 100 microm long and {001} twinned by metric merohedry, were obtained as a side-product of a hydrothermal run devoted to synthesizing the heterophyllosilicate lamprophyllite. Single-crystal X-ray diffraction data were collected on a Bruker-AXS Smart Apex diffractometer from a crystal with approximate composition (Ba(0.80)Sr(0.20))(4)Ti6Si4O24 x H2O. The structure was solved and refined as a disordered structure in the space group Cmmm [a(o) = 5.906 (2), b(o) = 20.618 (8), c(o) = 16.719 (6) A, R = 0.089 for 682 reflections with I(o) > 2sigma(I(o))], and then deciphered by the order-disorder (OD) theory as an ordered structure and refined in the space group P2/c [a = 5.906, b = 16.719, c = 10.724 A, beta = 105.99 degrees , R = 0.083 for 1090 reflections with I(o) > 2sigma(I(o))]. The discussion based on the OD theory shows that the refined ordered structure corresponds to one (2M) of two maximum degree of order (MDO) polytypes. The structure of the second MDO polytype (4O) was modelled but not refined because it does not substantially occur in our sample. In the structure, infinite (001) ribbons of Ti octahedra elongated along the [100] direction are connected by (SiO3)4 four-membered rings, thus realising a new type of heteropolyhedral framework. The ribbons are three-octahedra wide and one-octahedron thick; they are formed by linking, via edge-sharing, rutile-type edge-sharing rows of octahedra. This ribbon represents a slice of the octahedral sheet that occurs in perrierite-(Ce), Ce4MgFe2Ti2O8(Si2O7)2. The (Ba,Sr) ions are hosted within two independent [100] narrow channels both delimited by four Ti octahedra and four Si tetrahedra. The disorder of H2O is discussed on the basis of a Raman spectrum.

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.

Spectroscopic, microchemical and petrographic analyses of plasters from ancient buildings in Lamezia Terme (Calabria, Southern Italy).

This work shows the results of the spectroscopic, microchemical and petrographic study carried out on six plasters coming from three important residential buildings of the 18th century, located in Lamezia Terme (Catanzaro, Southern Italy). To study the provenance of the raw materials used to make the plasters, one sample of limestone and two samples of sand were also collected from the quarries near Lamezia Terme and compared with the historical plasters. Samples were studied by polarized optical microscopy (OM), X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and Raman spectroscopy. The results of these analyses allowed to determine the mineralogical, petrographical and chemical characteristics of the plasters, identify the pigments used for their coloration and provide useful information about the building techniques, the raw materials employed and the production technology of plasters during the 18th century in Lamezia Terme. SEM-EDS microanalysis also revealed the presence of gold and silver on the surface of two samples.

Effects of source rocks, soil features and climate on natural gamma radioactivity in the Crati valley (Calabria, Southern Italy).

The study, which represents an innovative scientific strategy to approach the study of natural radioactivity in terms of spatial and temporal variability, was aimed to characterize the background levels of natural radionuclides in soil and rock in the urban and peri-urban soil of a southern Italy area; to quantify their variations due to radionuclide bearing minerals and soil properties, taking into account nature and extent of seasonality influence. Its main novelty is taking into account the effect of climate in controlling natural gamma radioactivity as well as analysing soil radioactivity in terms of soil properties and pedogenetic processes. In different bedrocks and soils, activities of natural radionuclides ((238)U, (232)Th (4) K) and total radioactivity were measured at 181 locations by means of scintillation γ-ray spectrometry. In addition, selected rocks samples were collected and analysed, using a Scanning Electron Microscope (SEM) equipped with an Energy Dispersive Spectrometer (EDS) and an X-Ray Powder Diffraction (XRPD), to assess the main sources of radionuclides. The natural-gamma background is intimately related to differing petrologic features of crystalline source rocks and to peculiar pedogenetic features and processes. The radioactivity survey was conducted during two different seasons with marked changes in the main climatic characteristics, namely dry summer and moist winter, to evaluate possible effects of seasonal climatic variations and soil properties on radioactivity measurements. Seasonal variations of radionuclides activities show their peak values in summer. The activities of (238)U, (232)Th and (4) K exhibit a positive correlation with the air temperature and are negatively correlated with precipitations.

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, ß-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.