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The natural occurrence of asbestos and asbestos-like minerals (NOA) poses a risk to the environment and human health, notably when natural processes and anthropic activities promote fibre dispersion. Hundreds of potentially hazardous elongate mineral particles (EMPs, NIOSH 2011 definition) exist, and their toxicological profile is often unknown. We aim here to define a general approach, from field analysis to nano-structural investigation, to assess whether a fibrous mineral occurring in a specific site could pose a risk to human health. To evaluate the hazard associated with NOA, a multi-scale and multi-analytical integrated approach was adopted. Specifically, the geological factors that control the occurrence and distribution of NOA on site, and the mechanisms of formation and liberation of airborne fibres were investigated. In parallel, we explored the key bulk and surface properties of several natural mineral fibres and defined crystallographic, chemical, and morphological aspects that should be considered during hazard assessment. Also, the effect of standardized mechanical stress was used to quantitatively evaluate the potency of NOA-bearing exposed rock to generate inhalable fibres. This property was connected with the mineral characteristic, the rock fabric, and the rock erosion rate. Isolated fibre specimens were used to assess solubility in simulated body fluids, surface reactivity, and toxicological endpoints in vitro and in vivo. Taken together, these findings allowed us to build a multidimensional description of the hazard parameters of mineral fibre and paved the way for a science-based risk assessment in an unexplored NOA site.

The natural occurrence of asbestos and asbestos-like minerals (NOA) poses a risk to the environment and human health, notably when natural processes and anthropic activities promote fibre dispersion. Hundreds of potentially hazardous elongated mineral particles (EMPs, NIOSH 2011 definition) exist, and their toxicological profile is often unknown. We aim here to define a general approach, from field analysis to nano-structural investigation, to assess whether a fibrous mineral occurring in a specific site could pose a risk to human health. To evaluate the hazard associated with NOA, a multi-scale and multi-analytical integrated approach was adopted. Specifically, the geological factors that control the occurrence and distribution of NOA on site, and the mechanisms of formation and liberation of airborne fibres were investigated. In parallel, we explored the key bulk and surface properties of several natural mineral fibres and defined crystallographic, chemical, and morphological aspects that should be considered during hazard assessment. Also, the effect of standardized mechanical stress was used to simulate variation on morphometric parameters of investigated minerals and allowed us to quantitatively evaluate the potency to generate inhalable fibres. This property was connected with the mineral characteristic and the rock fabric. Isolated fibre specimens were used to assess solubility in simulated body fluids, surface reactivity, and toxicological endpoints in vitro and in vivo. Taken together, these findings allowed us to build a multidimensional description of the hazard parameters of a mineral fibre and paved the way for a science-based risk assessment in an unexplored NOA site.

Exposure to asbestos and asbestos-like minerals has been related to the development of severe lung diseases, including cancer and malignant mesothelioma (MM). A high incidence of non-occupational MM was observed in New Caledonia (France) in people living in proximity of serpentinite outcrops, containing chrysotile and fibrous antigorite. Antigorite is a magnesium silicate, which shares with chrysotile asbestos the chemical formula. To achieve information on antigorite toxicity, we investigated the physico-minero-chemical features relevant for toxicity and cellular effects elicited on murine macrophages (MH-S) and alveolar epithelial cells (A549) of three fibrous antigorites (f-Atg) collected in a Caledonian nickel lateritic ore and subjected to supergene alteration. Field Atg were milled to obtain samples suitable for toxicological studies with a similar particle size distribution. UICC chrysotile (Ctl) and a non-fibrous antigorite (nf-Atg) were used as reference minerals. A high variability in toxicity was observed depending on shape, chemical alteration, and surface reactivity. The antigorites shared with Ctl a similar surface area (16.3, 12.1, 20.3, 13.4, and 15.6 m

The investigated mantle bodies from the External Ligurians (Groppo di Gorro and Mt. Rocchetta) show evidences of a complex evolution determined by an early high temperature metasomatism, due to percolating melts of asthenospheric origin, and a later metasomatism at relatively high temperature by hydrothermal fluids, with formation of rodingites. At Groppo di Gorro, the serpentinization and chloritization processes obliterated totally the pyroxenite protolith, whereas at Mt. Rocchetta relics of peridotite and pyroxenite protoliths were preserved from serpentinization. The rodingite parageneses consist of diopside ​+ ​vesuvianite ​+ ​garnet ​+ ​calcite ​+ ​chlorite at Groppo di Gorro and garnet ​+ ​diopside ​+ ​serpentine ​± ​vesuvianite ​± ​prehnite ​± ​chlorite ​± ​pumpellyite at Mt. Rocchetta. Fluid inclusion measurements show that rodingitization occurred at relatively high temperatures (264–334 ​°C at 500 ​bar and 300–380 ​°C at 1 ​kbar). Garnet, the first phase of rodingite to form, consists of abundant hydrogarnet component at Groppo di Gorro, whereas it is mainly composed of grossular and andradite at Mt. Rocchetta. The last stage of rodingitization is characterized by the vesuvianite formation. Hydrogarnet nucleation requires high Ca and low silica fluids, whereas the formation of vesuvianite does not need CO2-poor fluids. The formation of calcite at Groppo di Gorro points to mildly oxidizing conditions compatible with hydrothermal fluids; the presence of andradite associated with serpentine and magnetite at Mt. Rocchetta suggests Fe3+-bearing fluids with fO2 slightly higher than iron-magnetite buffer. We propose that the formation of the studied rodingite could be related to different pulses of hydrothermal fluids mainly occurring in an ocean-continent transitional setting and, locally, in an accretionary prism associated with intra-oceanic subduction.

Covered by ultrabasic units for more than a third of its surface, the New Caledonia (South West Pacific) is one of the largest world producers of Ni-ore from lateritic deposits. Almost all outcrops of geological units and open mines contain serpentine and amphibole, also as asbestos varieties. In this geological context, in which weathering processes had a great contribution in the production and dispersion of mineral fibres into the environment, the development of a routinely analytical strategy, able to discriminate an asbestiform fibre from a non-harmful particle, is a pivotal requisite. However, the acquisition of all these parameters is necessary for determining the risk associated to fibres exposition. A multidisciplinary routinely approach, based on the use of complementary simply-to-use but reliable analytical methods is the only possible strategy. In addition, the instrumental apparatus must be easily transportable on the field, directly on the mining site. The employment of specialized tools such as Polarized Light Microscopy associated to Dispersion Staining method (PLM/DS) and portable Raman spectroscopy for identification of environmental asbestos, are proved extremely effective in the improvement of the performance and rapidity of data acquisition and interpretation. Both PLM/DS and handheld Raman devices confirmed to be discriminant in the detection and characterization of asbestos fibres for both serpentine and amphibole. Furthermore, these techniques proved extremely effective even in the presence of strongly fibrous and altered samples. Keywords: Asbestos, Fibrous antigorite, In situ monitoring, Dispersion staining, Portable Raman, New Caledonia

The occurrence of asbestos and asbestos-like minerals in natural sites may pose a risk to human health and the environment when rocks and soils are mobilized. Weathering and anthropic activities favour the liberation of potentially hazardous Elongated Mineral Particles (EMP, NIOSH 2011). The definition of EMP includes both asbestos and other fibrous minerals. The latter share several physical-chemical properties with asbestos, but their toxicological profile is still unknown. The assessment of risk requires the quantification of the occurrence and the estimation of the potential emissivity of EMP from the hosting matrix.We quantitatively described the potency of a rock to disperse EMPs in the environment with a quantitative parameter namely the “liberability factor” (Lf). Lf was measured for 40 meta-ophiolite fragments from the NOA-bearing units of Liguria (Voltri Group and Sestri-Voltaggio Zone) and Calabria (Gimigliano-Monte Reventino Unit, Southern Ligurian Domain). The mineral–petrographic characterization of these rocks showed the presence of veins of chrysotile, fibrous tremolite-actinolite, fibrous sepiolite and fibrous antigorite.By adapting the UNI EN 12457-2:2004 method for solid waste, we designed a weathering simulation test to quantify the EMPs and the fibres (according to the World Health Organization) possibly liberated by applying to the rock a standardized mechanical stress. Waterborne EMPs were filtered on membranes and counted by electron microscopy (SEM-EDS), by adapting the Italian Regional Agency for the Protection of the Environment (ARPA) procedure for waterborne asbestos (ARPA Piemonte, 2016). We obtained Lf values as the number of waterborne fibres suspended per unit volume of water (fibres/Litre). All analysed rock samples showed Lf values ranging from 30 Mf/L to 21’000 Mf/L. Chrysotile, tremolite, sepiolite, and antigorite, with asbestos-like habit, were detected.Lf proved to be a reliable, easy to use method for the characterization and prediction of EMP and fibre dispersion in the environment from NOA-bearing rocks subjected to a standardized mechanical stress. This study is part of the BRIC 2019 project (grant number ID 57.1) supported by INAIL (Italian National Institute for Insurance against Accidents at Work). ReferencesARPA Piemonte 2016. U.RP. M842 rev.03. Asbestos in water by Scanning Electron Microscopy. NIOSH, 2011. Asbestos fibers and other elongate mineral particles. Current Intelligence Bulletin 62. WHO, 1997. Determination of Airborne Fibre Number Concentrations. ISBN 92 4 154496 1

Asbestos inhalation is associated with fatal respiratory diseases and raises concerns from the perspective of workplace safety and environmental impacts. Asbestos and asbestos-like minerals naturally occur in rocks and may become airborne when outcrops or soils are disturbed by anthropic activities. In situ detection of these minerals is a crucial step for the risk evaluation of natural sites. We assess here whether a portable Raman spectrometer (pRS) may be used in the identification of asbestos and asbestos-like minerals at the mining front during exploitation. pRS performance was tested at three geologically different mining sites in Italy and New Caledonia and compared with a high-resolution micro-Raman spectrometer (HRS). About 80% of the overall in situ analyses at the mining front were successfully identified by pRS, even when intermixed phases or strongly disaggregated and altered samples were analyzed. Chrysotile and tremolite asbestos, asbestos-like antigorite, and balangeroite were correctly detected during surveys. The major difficulties faced during in situ pRS measurements were fluorescence emission and focussing the laser beam on non-cohesive bundles of fibers. pRS is adequate for discriminating asbestos and asbestos-like minerals in situ. pRS may support risk assessment of mining sites to better protect workers and environment.

Exposure to natural occurrences of asbestos (NOA) and other potentially hazardous elongated mineral particles (EMPs) may pose a risk to human health and the environment. Weathering forces and anthropic activities may alter the cohesion of NOA-bearing outcrops and disperse EMPs in air, water, and soil. The current paradigm for fibre toxicity indicates that morphology and crystal chemistry are key parameters in determining the toxicological properties of a mineral. This work aims to assess and discuss the impact of sub-tropical supergene alteration and weathering on the morphology and the chemical composition of antigorite, a non-regulated serpentine that shares chemical composition with asbestos chrysotile. Antigorite naturally occurring in lateritic Ni ores of New Caledonia exhibits a unique asbestos-like habit at the microscopic scale. Standardized mechanical stress was performed on antigorites, selected to represent different cohesion states. The specimens produced a relevant amount of respirable fibres, between 32 and 42% (WHO counting criteria). PCA on chemical data and ternary diagrams show that all antigorites exhibit a similar Si content (from 2.05 to 2.09 a.f.u.) but were mainly differentiated by Mg and Ni content, ranging from 2.66 to 2.80 and 0.00 to 0.09 a.f.u., respectively. Si content in Caledonian antigorite is higher than Si in non-lateritic samples. This suggests that a main alteration process occurred after the obduction of the ultramafic protolith. The supergene alteration determined the Ni enrichment of lateritic deposits and is likely the main cause of the mineral alteration of antigorite under sub-tropical environments. Further, weathering processes prompt the disaggregation of altered antigorite causing the generation and dispersion of respirable, potentially hazardous, antigorite fibres in the environment.

Open-pit nickel mining is the main economic activity in New Caledonia. Lateritic Ni-ore deposits formed on weathered ultrabasic rock cover more than a third of the territory. However, among the mineral phases that make up these laterites, some belong to the asbestos family and have the capacity to emit pathogenic fibres. The inhalation of air polluted by such fibres may lead to severe respiratory diseases; asbestos may penetrate deep into the lungs causing at worst malignant mesothelioma.In order to manage the natural occurrence of these fibres and take the necessary measures for the protection of workers, it is necessary to evaluate and monitor the concentration of asbestos fibres into the environment (e.g., airborne, waterborne). The current monitoring approach adopted by asbestos laboratories relies on counting method using Transmission Electron Microscopy (TEM), according to French regulation (NF X 43-050). Analysts operatively count and measure fibres and elongated mineral particles (EMPi) with on a filter viewed through the microscope device at high magnification. It is worth noting that analytical procedures involving electron microscopies are time-consuming, and show an intrinsic bias related to the subjectivity of operator analysis. These drawbacks explain the need to develop an automatic method for fibre and EMPi detection and quantification.This paper presents a new method for detecting fibres on filters by using image processing and machine learning methods, discriminating single fibres, particles, juxtaposed objects and fibre bundles, minimizing as much image noise.

The rising awareness about the risk due to asbestos environmental exposure has led to a new interest in the investigation of non-regulated mineral fibers. Evidence of chronic diseases has been described in individuals exposed to naturally occurring asbestiform (NOA) minerals in Turkey (erionite), Italy (fluoro-edenite), and the United States (winchite/richterite). In New Caledonia, an increased incidence of asbestos-related diseases was correlated with the natural occurrence of fibrous serpentines chrysotile and fibro-lamellar antigorite in outcrops, roadways, and soils. A minor amount of tremolite asbestos was also observed, increasing the health hazard. By adopting a precautionary principle, New Caledonia legislation classified antigorite as regulated asbestos, even if limited toxicity assessment is available. Caledonian antigorite exhibits a wide range of natural shapes, morphologies, and degrees of alteration as a result of pedogenic alteration induced by subtropical conditions. As the alteration increases, lamellar antigorite gradually cleaves into fibrous-like particles, assuming a fibro-lamellar habit. An increase in the emission of inhalable (potentially asbestiform) fibers in air was observed. To understand this mechanism, a multidisciplinary mineralogical and geochemical investigation was carried out. Additionally, several in vitro tests have been performed on three antigorite samples, subjected to different levels of alteration, to collect preliminary information on antigorite toxicity. Alteration modifies the surface reactivity of antigorite. The circulation of fluids induces a mechanical stress and an elemental exchange at mineral/water interface, promoting the loss of cohesion of the mineral structure and affecting the surface chemistry and toxicity of fibrous (asbestiform) antigorite.

Anatase nanoparticles in suspension have demonstrated high photoactivity that can be exploited for pollutant removal in water phases. The main drawback of this system is the difficulty of recovering (and eventually reusing) the nanoparticles after their use, and the possible interference of inorganic salts (e.g., sulfates) that can reduce the performance of the photocatalyst. The present work describes the development of a cordierite-honeycomb-supported TiO2 film to eliminate the problems of catalyst recovery. The catalyst was then tested against phenol in the presence of increasing concentrations of sulfates in a specially developed recirculating modular photoreactor, able to accommodate the supported catalyst and scalable for application at industrial level. The effect of SO42&minus, was evaluated at different concentrations, showing a slight deactivation only at very high sulfate concentration (&ge, 3 g L&minus, 1). Lastly, in the framework of the EU project Project &Ocirc, the catalyst was tested in the treatment of real wastewater from a textile company containing a relevant concentration of sulfates, highlighting the stability of the photocatalyst.

Le programme « ABP, Amiante et bonnes pratiques », a proposé une étude intégrée et pluridisciplinaire depuis l’identification jusqu’au caractère pathogène des fibres issues des minéraux amiantifères présents en secteur minier néo-calédonien.- Au travers d’un échantillonnage d’un panel représentatif des asbestes présents (famille des serpentinites et des amphiboles), les minéralogies, les propriétés physico-chimiques et toxicologiques de ces minéraux amiantifères ont été caractérisées.- À noter que le programme ABP a apporté les premières données toxicologiques sur les fibres d’amiante néo-calédoniennes. Un intérêt particulier est porté sur l’antigorite, minéral fibreux très présent sur le territoire calédonien, notamment en secteur minier, mais non répertorié comme amiante dans la législation hors territoire.

Serpentinites are rocks, often used in buildings, formed in large extent by minerals of the serpentine group: chrysotile, antigorite, lizardite, and polygonal serpentine. The fibrous type (e.g. chrysotile) of serpentine group minerals, along with several amphibole varieties (e.g. actinolite and tremolite), are the major components of asbestos family. The exposure to fine fibrous asbestos powder is linked to diseases such as pleural mesothelioma and asbestosis. The identification of the main varieties of the serpentine group, laminated or fibrous, becomes an issue of great interest for public health. This work introduces an analytical strategy able to distinguish the different serpentine polymorphs directly on the sample, allowing the analysis within their textural environment, evidencing at the micrometer scale the mineral reactions of the phases. Samples coming from the Koniambo massif (Grande Terre Island, New Caledonia) were studied by means of optical microscopy, scanning electron microscopy–energy dispersive X-ray spectroscopy, and Raman spectroscopy. Raman peaks observed in the high wavenumber spectral range of 3550–3850 cm−1, associated with OH stretching vibrations, allow the discrimination of the all four serpentine varieties. The relationship between the different varieties of serpentine, at a micrometric scale, in complex samples, has been investigated by two-dimensional Raman mapping. Copyright © 2015 John Wiley & Sons, Ltd.