Displays

The government of California, in the United States, has created requirements that are intended to protect the public from naturally occurring asbestos (NOA), partly due to the widespread areas in which asbestos minerals (including chrysotile and various amphiboles) are found within the state.Over ten years ago, the California Department of Toxic Substances Control Schools Unit published a thorough set of guidelines for addressing NOA at school construction sites.Their guidance document includes soil sampling procedures and frequency, recommended laboratory analytical testing methods, construction best practices to protect nearby residents from airborne exposures, capping methods to prevent re-exposure to students and public following the completion of the school improvement project, and follow-up procedures to ensure the capping method remains protective.Many of these best practices have been adapted into the construction process for commercial and residential buildings.  In California, protection of air is the regulated by Air Quality Management Districts, who regulate the generation of airborne asbestos as an air pollutant.Additionally, workers who are employed by a company, and working at a job site where asbestos is present, are protected by California Occupational Safety and Health (Cal-OSHA). Cal-OSHA requires varying protective measures to be implemented, based on the amount of asbestos that the worker is exposed to during their time at the construction project.This presentation will review the various regulations and best practices used in California by comparing a school construction project with a commercial office building.

How to cite: Kalika, S.: Naturally Occurring Asbestos Assessment, Exposure Prevention Strategies During Construction, and Capping for Long-Term Protection: a California, USA Example, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1366, https://doi.org/10.5194/egusphere-egu2020-1366, 2020.

Italy was one of the largest producers of asbestos-containing minerals and materials (ACM), with large areas affected by natural asbestos (NOA). In 1992 Italy began the first reclamation activities at the largest European asbestos mine in Balangero (Piedmont) and in 2001 in minor mines in Valle d'Aosta (Emarese), also adopting specific reclamation procedures and protective measures for the workers. Also in 2001, reclamation work was started in Biancavilla etnea (Sicily), a city with a great contamination from two quarries containing fluorine-edenite, an amphibole of volcanic origin recognized as a category 1A carcinogen by the IARC. Although the asbestos extraction and asbestos containing materials trading has been banned since 1992 (Law n.257/92), to now, the extraction of green stones as inert or ornamental stone and other anthropic activities (eg the digging, tunneling or farming activities in areas with potentially contaminated soils) are still going on in many quarry districts and wide areas, with no regulations if not at local level.

The only legislative act concerning NOA has been enacted in 1996 (the 14/5/96 decree) and it’s mainly referred to "green-stones" identification in mines and quarries. From that date no further act has been approved on NOA.

In this context, to fill the gap, Inail (Dit and Contarp) issued the NOA Project to take the most correct workers’ protection actions in the management of a territory, as NOA.

The project lists the different activities carried on in areas with green stones occurrence with a workers' potential asbestos exposure risk, together with an analysis of the specific prevention and protection measures.

The activities are:

• Extraction and processing of ornamental stones and inert gravel

• Remediation of NOA contaminated sites, slopes rearrangement and restoration works of hydrogeological instability

• Excavations for road and railway tunnels

• Excavations and urbanization at different scales

• Farming.

· Railway ballast removal and disposal / remediation.

In the final document, in the drafting phase, we also propose an updated definition of NOA sites as:

“Asbestos minerals contained in ophiolitic rocks, outcropped or buried, in variable amount and localization, not definable in advance, whose fibers can be released into the environment due to anthropic activities or exogenous agents”.

How to cite: Malinconico, S., Conestabile della Staffa, B., Guercio, A., Paglietti, F., and Rimoldi, B.: Natural Occurring Asbestos (NOA) in Italy: Workers' potential exposure risks and prevention and protection measures, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4918, https://doi.org/10.5194/egusphere-egu2020-4918, 2020.

New Caledonia, a French overseas territory, is located in the southwest of the Pacific Ocean, less than 2,000 km from both the Australian and New Zealand coasts. This small archipelago (18,575 km2) presents the third largest nickel deposit in the world and, according to recent estimates, would have more than 25% of the world's nickel resources and about 40% of the world's oxidized mineral resources, together with the presence of cobalt, chromium and manganese. The mining areas, spread over the whole ‘Grande Terre’ (mainland), comprise about 250,000 hectares of scattered concessions shared by French and international world scale mining and metallurgic companies and a few other local small-scale miners.

To face the challenges of a “better way of mining”, fit the new regulatory requirements and improve mining social acceptability, the mining sector stakeholders decided to create a dedicated resource agency devoted to applied research and technology development in New Caledonia’s mining industry. Created in 2007, this unique public and private organisation jointly involves all New Caledonian’s mining companies, political and administrative stakeholders and various scientific research bodies.

Research has focused on three identified areas (technology and mineral resources, natural environment and social issues) to fill on-going gaps in fundamental knowledge, offer and adapt new technology that is relevant to the industry, develop methodology aids, manage knowledge transfer and upgrade practices on the ground. If action of CNRT has effectively added value to New Caledonian research, at the same time it permanently keeps in touch with industry.

A presentation of some of the flagships scientific programs will give an overview of the main achievements in the three research areas with a focus concerning works on asbestos. CNRT started working on the environmental asbestos hazard in New Caledonia since 2010. This public health area is being examined alongside the New Caledonian Geological Survey and the various industry initiatives, such as the Inter-Mine Environmental Asbestos Committee.

How to cite: Bailly, F.: New Caledonia, a land of Nickel - Research and innovation acting for the sustainable development, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6163, https://doi.org/10.5194/egusphere-egu2020-6163, 2020.

Naturally occurring asbestos (NOA) occurs in rocks and soils as a result of natural weathering and human activities. It is proved that inhalation of asbestos fibers can lead to increase risk of developing several diseases such as lung cancer and malignant mesothelioma. The parent rocks of asbestos have been mainly associated with (ultra)mafic and carbonate rock. The previous studies on NOA were mainly limited to (ultra)mafic rock-hosted asbestos in S. Korea, but studies on carbonate rock-hosted asbestos are relatively rare in S. Korea. Therefore, this study was aimed to examine mineralogical characteristics of carbonate rock-hosted NOA. Types of rocks at the several sites mainly consisted of Precambrian metasedimentary rocks, carbonate rock, and Cretaceous and Jurassic granites. Asbestos-containing carbonate rock samples were obtained for mineralogical characterization. XRD, PLM, EPMA, SEM and EDS analyses were used to characterize mineralogical characteristics of the carbonate rock-hosted NOA. From the carbonate rock, fibrous minerals were occurred acicular and columnar forms in the several sites. Fibrous minerals were composed of mainly tremolite, actinolite, and associated minerals included possibly asbestos containing materials (ACM) such as talc, vermiculite, and sepiolite. The length and aspect ratios of tremolite and actinolite were similar to the standard asbestiform (length >5 ㎛, length:width = 3:1). These results indicate that both non-asbestiform and asbestiform tremolite and actinolite with acicular forms occurred in carbonate rocks at several sites. Geological and geochemical characteristics and mineral assemblages indicate tremolite and associated minerals might be formed by hydrothermal alternation and/or hydrothermal veins of carbonate rocks due to intrusion of acidic igneous rocks.

How to cite: Roh, Y., Park, B. P., Kim, Y., Park, J., Kim, H., Jeong, H., and Yoon, S.: Mineralogical Characteristics of Carbonate Rock-Hosted Naturally Occurring Asbestos from Republic of Korea, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7737, https://doi.org/10.5194/egusphere-egu2020-7737, 2020.

In Germany, there has been an exemption for the use of mineral raw materials containing asbestos since 1993 on the basis of the Hazardous Substances Ordinance. While activities involving asbestos or materials containing asbestos are generally prohibited since that time, demolition/maintenance work and working involving asbestos containing mineral raw materials (maximum permissible asbestos content: 0.1 mass%) are permitted, subject to compliance with defined protective measures. Activities involving mineral raw materials containing asbestos (e.g. talcum, gravel) NOA are usually released from tremolite / actinolite or anthophyllite, in a few cases also chrysotile / antigorite. The occurrence of grunerite or riebeckite is the exception. In occupational health and safety, analytical methods for determining exposure are limited to the detection of fibres with critical dimensions (L > 5 µm, D < 3 µm, L:D > 3:1; so-called WHO fibres). For this purpose, an extended definition of asbestos has been laid down in the Special Technical Rules for Hazardous Substances ("TRGS" 517), which concerns the chemical composition and morphology of the NOAs to be determined. It was also necessary to establish a convention by means of which asbestos minerals can be distinguished from other chemically similar minerals. In Germany, the determination of asbestos fibre concentrations is usually carried out by means of SEM-EDX analysis. The convention therefore refers to a distinction based on certain element contents and their ratios. This catalogue of criteria is freely available in the form of an EXCEL sheet. This ensures that different laboratories achieve comparable results. On this basis, exposure measurements have been carried out by the measurement services of the accident insurance institutions since about 1998. Measurement results are presented from the extraction of rocks in quarries, the cold milling of road pavings, the use of talcum and from asphalt mixing plants, among others. Depending on the determined exposure level, protective measures have to be taken for the activities concerned. In addition to general protective measures, special protective measures have been defined for specific industries. For the determination of the asbestos content in mineral raw materials, the TRGS 517 defines four specific determination procedures, including a procedure based on a dustiness test.

How to cite: Mattenklott, M.: The identification and assessment of asbestos exposure from mineral raw materials in Germany - definitions, conventions, analytical methods, exposure situation and protective measures, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10543, https://doi.org/10.5194/egusphere-egu2020-10543, 2020.

For a reliable evaluation of the geo-environmental risk related to the presence of naturally occurring asbestos (NOA) in rocks excavated for large infrastructural projects, a proper procedure has to be followed in order to achieve:

1) the definition of a detailed geological model, tailored on NOA-related issues;

2) a representative sampling;

3) a reliable quantitative determination of asbestos content in rock samples.

Here we describe the approach followed for the evaluation of the NOA content for the excavation of a complex highway tunnel system (“Gronda di Genova” NW Italy), in NOA-bearing meta-ophiolite rocks. The NOA-oriented geological model has been constrained by the individuation of the main “NOA-related petrofacies” —i.e., classes of rocks with common lithological, structural and NOA content features—, and by the identification of “homogeneous zones” – i.e. geological units into which the NOA petrofacies are distributed. Implementation of Gy’s theory on sampling was used and here described to maintain statistical validity during sample processing from the primary rock sample to the analytical sample. SEM-EDS procedure for the quantitative determination of NOA content was improved with an error analysis delivering the minimum number of fibers to be measured to achieve the best analytical results.

The obtained results allowed the prediction of the NOA hazard in terms of risk zonation along the tunnel section and for the evaluation of the amount of asbestos-bearing spoil to be excavated and managed.

How to cite: Piana, F., Avataneo, C., Barale, L., Botta, S., Compagnoni, R., Cossio, R., Marcelli, I., Tallone, S., and Turci, F.: Assessment of NOA risk for the excavation of a highway tunnel system ("Gronda di Genova", Italy): from NOA-oriented geological model to asbestos quantification, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10105, https://doi.org/10.5194/egusphere-egu2020-10105, 2020.

This paper presents the results of 810 pre-project baseline samples collected over four years (2010-2011), and 7,210 offsite (ambient) and 14,314 perimeter samples collected over 7 years (2012-2018) during the CDRP project. The principal asbestos particles were chrysotile from serpentinite, and glaucophane-winchite amphibole from blueschist. The baseline data showed that asbestos concentrations measured at each station are not representative of a regional average background, rather, they reflect contributions from several variables such as: location on or near NOA-containing units, wind direction, intensity of localized soil disturbance, and time of year. The data shows that baseline sampling prior to a project cannot be used as a measure of “background” during the project. The analysis of amphibole composition in air and rock/soil samples was applied to differentiate local source impacts from the primary CDRP asbestos emissions. Of particular value was the application of the calcic-amphibole to total amphibole ratio (Ca index) measured during ABS sampling and comparison with the ratios measured in the samples. This analysis delineated three primary amphibole sources: 1) alluvium in the Sunol Valley with a high Ca index, 2) imported road surfacing material with a moderate Ca index, and 3) blueschist with a low Ca index. When the data was sorted by wind direction, the analysis showed that the contribution of CDRP-generated asbestos to monitoring stations was significant near the point of disturbance only, and did not significantly impact offsite stations that were located at or near sensitive receptors. The asbestos measured at the offsite stations were correlated with local geologic units. The analysis verified that the CDRP emissions were well below the project-specific risk-based thresholds established for the CDRP project, documenting that the offsite receptors were not exposed to an adverse risk by CDRP activities.

How to cite: Erskine, B. and Bailey, M.: Analysis of Baseline and Perimeter Air Monitoring Data from the Calaveras Dam Replacement Project (CDRP), Fremont, California, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22383, https://doi.org/10.5194/egusphere-egu2020-22383, 2020.

Ferrierite is the name of a family of zeolite minerals that includes three species with the same topological framework (FER) but with different content of extra-framework cations. In Nevada (USA), the zeolite-rich tuff deposit of Lovelock is the largest occurrence of diagenetic ferrierite-Mg, one of the member of the family. Recent studies have shown that Lovelock ferrierite can exhibit fibrous-asbestiform crystal habit and may possess the same physical-chemical and crystallographic properties of carcinogenic fibrous erionite, Nevertheless, it has not yet been classified by the International Agency for Research on Cancer (IARC). Nowadays, outcrops hosting fibrous ferrierite are being mined in Nevada for commercial purposes. Dust generated by these excavation activities may expose workforces and general public to this potential natural hazard. The main goal of this study was to perform a mineralogical and morphometric characterisation of the tuff deposit at Lovelock and evaluate the distribution of fibrous ferrierite in the outcrop. For this purpose, a multi-analytical approach including X-ray powder diffraction, scanning and transmission electron microscopy techniques, micro-Raman spectroscopy, thermal analyses, and surface-area determination was applied. The results indicate that fibrous ferrierite is widespread in the deposit and intermixed with mordenite and feldspar, although there are variations in the spatial distribution in the bedrock. The crystal habit of the ferrierite ranges from prismatic to asbestiform (elongated, thin and slightly flexible) and fibres are aggregated in bundles. According to the WHO counting criteria, most of the ferrierite fibres can be classified as breathable. While waiting for confirmatory in vitro and in vivo tests to assess the actual toxicity/pathogenicity potential of this mineral fibre, it is recommended to adopt a precautionary approach for mining operations in this area to reduce the risk of exposure.

How to cite: Gualtieri, A., Zoboli, A., Di Giuseppe, D., Baraldi, C., Gamberini, M. C., Malferrari, D., Lassinantti Gualtieri, M., and Bailey, M.: Fibrous ferrierite from Lovelock, Nevada, USA, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5441, https://doi.org/10.5194/egusphere-egu2020-5441, 2020.

The French Ministry of Health, Ministry of Labor and Ministry of Environment are faced with the emerging issue of cleavage fragment particles with same chemical composition as actinolite asbestos in aggregates used in road pavement. In 2015, the National Agency for Food, Environmental and Occupational Health and Safety (ANSES) published a literature review on the health effect of these non asbestiform particles. The conclusion is that any study can show the evidence of risk absence related to these particles.

After this first report, the French government mandated the national agency to conduct a research on the emission source of EMPs of interest (EMPi; ANSES, 2017). These particles correspond to the asbestiform and non-asbestiform varieties of the six regulated asbestos minerals and to four other mineral fibers. The agency recommends following the precaution principle by applicating the asbestos regulation to these whole particles. It also recommends leading a measurement campaign for exploring the potential exposure of workers and general population to EMPi during some construction activities.

In this context, the three ministries asked in 2017 the Professional Organization for Risk Prevention in Building and Public Work Sector (OPPBTP) to coordinate a project on EMPi, based on the requirements of the ANSES second report. This national project, called Carto PMAi, addresses the potential exposure of populations to EMPi, in order to provide reliable data to the three ministries to set up legal provisions. The first step is to build reliable protocols to measure EMPi in materials and in the air. Several national scientific organisms and asbestos testing laboratories take part at this phase that includes interlaboratory comparisons. The second phase is the measurement campaign in construction areas, including quarries and earthwork in natural environment.

How to cite: Leocat, E., Deneuvillers, C., and Richard, P.: Carto PMAi : a measurement campaign to evaluate the exposition of the workers and the general population to the EMP of interest , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19651, https://doi.org/10.5194/egusphere-egu2020-19651, 2020.

During the mining and processing of some mineral commodities and other rock types there is the potential to produce respirable dust containing naturally occurring elongate mineral particles (EMPs), including both asbestos and/or non-asbestos fibers. The United States National Institute for Occupational Safety and Health (NIOSH) estimated that 44,000 mine workers may be exposed to EMPs. EMPs have been documented to cause lung cancer and mesothelioma in humans in addition to fibrotic lung disease (asbestosis), with some estimating up to 76,700 EMP-caused lung cancer deaths between the years of 1980 and 2009. Unfortunately, there is little information available relating the geologies of the materials being mined to the potential for EMP exposure to mine workers. There is a strong need for research on fundamental mineralogical properties of EMPs—relevant to toxicology, epidemiology, and exposure assessment— and their geographic distribution, which industry can use as a basis for exposure monitoring and miner protection. This presentation will outline the NIOSH research addressing these concerns including; 1) assessment of miners’ potential exposure to asbestos and other EMPs by analyzing bulk material samples previously collected from copper, granite, gold, iron, limestone, sand and gravel, coal, and other types of mines across the country, 2) further elucidation of the toxicology of EMPs by creating new separation methods to allow both in vitro and in vivo toxicity tests on EMPs of specific lengths, widths and other characteristics of concern, 3) establishment of an application of qualitative and quantitative analysis of regulated asbestos and other EMPs for end-of-shift measurement using newly developed and novel techniques for EMP analysis, and 4) making new reference materials (anthophyllite asbestos and actinolite-tremolite asbestos) available to laboratories analyzing the elongate mineral particle fraction of bulk rocks and airborne dusts, and for toxicity testing.

How to cite: Mischler, S.: NIOSH Elongate Mineral Particle Research, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9002, https://doi.org/10.5194/egusphere-egu2020-9002, 2020.

The determination of the asbestos content in ophiolitic rocks is carried out by well-known and standardized analytical techniques (SEM-EDS according to Italian regulation on environmental parameters on spoils, waste and rock and soil). Despite the high resolution and the possibility to obtain elemental information, SEM-EDS is not always able to discriminate serpentine minerals, including chrysotile and non-regulated fibrous antigorite, lizardite, and possibly polygonal serpentine.

Moreover, the analytical procedures using electron microscopies are time-consuming and show an intrinsic lack of statistical representativeness, due to the low portion of the analytical sample that is effectively analyzed. Conversely, optical microscopy delivers fast results affected by a lower resolution and unreliable mineral fibre identification. Many sectors related to the realization of geo-engineering projects would take enormous advantages from a more efficient and statistically-sound approach.

To evaluate the results obtained from a state-of-the-art optical microscope with automatic image analysis in-line with micro-Raman spectrometer, we designed a study to comparatively determine the asbestos content from a large set of samples deriving from asbestos-bearing rock of the ophiolitic domain. The performance of a Malvern G3 Morphology microscope equipped with a 850 nm laser Raman spectrometer was tested on 40 samples. The same samples, prepared from ophiolitic rocks from the Ligurian Alps comminuted down to top-size = 100 μm, were parallelly analyzed and results compared with SEM-EDS quantitative method described by Italian regulation (Ministerial Decree 6 September 1994, All 1B).

How to cite: Trapasso, F., Tempesta, E., Passeri, D., Belardi, G., Petriglieri, J. R., Avataneo, C., Compagnoni, R., Piana, F., and Turci, F.: Asbestos determination in ophiolitic rocks by Image Analysis coupled with Raman Spectroscopy, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20813, https://doi.org/10.5194/egusphere-egu2020-20813, 2020.

Retrograde metamorphism corresponds to the metamorphic processes that occur during orogenic uplift (diminishing temperatures) and cooling (lowering temperatures). These pressure and temperature conditions induce fracturing and fluids circulation which may prompt the crystallization of fibrous actinolite and tremolite within magnesium-iron rich rocks. Such fibrous amphiboles may result from the destabilization of earlier minerals (magmatic or metamorphic pyroxenes and/or amphiboles). In all cases, fibrous occurrences concern discrete locations and limited extents in space. These Naturally Occurring Asbestos minerals only form along fracture planes (in slip-vein mode) or within open veins (cross-vein mode). That is in the space where fluids circulated. Actinolite and tremolite minerals also crystalize inside mafic rock matrix, though not under their asbestiform habitus. Altering fluids diffuse from vein walls into the rock and actinolite and tremolite substitute themselves to destabilized pyroxenes and amphiboles of the matrix. This deliberately simplified geological logic may be used  to predict the location of Naturally Occurring Asbestos (NOA) on different rock outcrops.

We contend that 3D digital outcrop models commonly acquired by photogrammetry (ground- or UAV-based) alone or together with lidar, are efficient supports to map NOA presence susceptibility using this conceptual model. The rock assemblage architecture is best interpreted either in 3D, on a photorealistic textured meshed model itself, or on 2D orthophotos projected on a vertical plane. Geometric processing of dense (centimeter-resolution) 3D point clouds enables identifying host structures (fractures, faults and layer contacts) in the outcrop relief. Already, with these information supported by field observations, a first model may be produced for most likely NOA sites on the outcrop. If hyperspectral imaging in the shortwave infra-red (1300-2500 nm) spectral range, constrained by point-based field spectrometer acquisition, is added to the pool of available data sets, diffuse alteration rings of the mafic rock matrix may be imaged and included to the presence susceptibility model. Amphibole mineralogy provides diagnostic spectral properties due to hydroxyl absorption and can be therefore identified and mapped by hyperspectral imaging in the outcrop.

This theoretical approach to mapping NOA presence susceptibility is demonstrated on examples from Norway and France. Ground-based photogrammetric survey replicates the geometry and colour of the outcrop with a dense point cloud spacing of 1pt/15-20 mm and a photorealistic textured meshed model. Lithological architecture and structural interpretation were performed manually using LIME software (virtualoutcrop.com). Geometric fracture mapping was undertaken using CloudCompare (cloudcompare.org) with the Compass and Facets plugins. Both lithological and structural information were brought together on a 2D NOA presence susceptibility map using Geographic Information System. This output, validated in the field, guides rock sample collection for laboratory analysis and objectivates their spatial representatitivity for NOA presence susceptibility reports.

How to cite: Dewez, T. J. B., Lahondère, D., Kurz, T. H., Naumann, M., Naumann, N., Capar, L., Cagnard, F., and Buckley, S. J.: Guiding Naturally Occurring Asbestos rock sampling using digital outcrops and geological reasoning , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18665, https://doi.org/10.5194/egusphere-egu2020-18665, 2020.

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.

How to cite: Selmaoui-Folcher, N., Galante-Gras, N.-C., Laporte-Magoni, C., Turci, F., and Petriglieri, J. R.: Machine learning for identification and counting of Naturally Occurring Asbestos, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21534, https://doi.org/10.5194/egusphere-egu2020-21534, 2020.

Aggregates (sand, gravel and crushed stone) characterized by good mechanical properties and no undesired reactivity, are used in huge amounts in many industrial sectors, especially in construction (e.g. concrete, asphalt, paving). Sand and gravel extracted from alluvial or glacial deposits are typically rounded and well selected, whereas crushed stone is angular and suitable for certain applications (e.g. railway ballast). Use of offshore deposits is mostly restricted to beach erosion control and replenishment. Demand for aggregates is governed essentially by markets, and sources of supply need to be situated close to each other, because of transportation costs. The most common rock types (depending on geology) are represented by basalts, porphyries, orthogneisses, carbonatic rocks and “green stones” (serpentinites, prasinites, amphibolites, metagabbros). Especially “green stones” may contain traces, and sometimes appreciable amounts of asbestiform minerals (chrysotile and/or fibrous amphiboles). For example in Italy, the chrysotile asbestos mine in Balangero (Turin) produced over 5 Mt railroad ballast (crushed serpentinites), which was used for in northern and central Italy, from 1930 up to 1990. The legal threshold for asbestos content in track ballast is established in 1000 ppm: if the value is below this threshold, the material can be used, otherwise it must be disposed of as hazardous waste, with very high costs. The presence of asbestiform minerals must be first assessed by preliminary geological and mineralogical surveys in quarry areas, both for glacial – alluvial deposits and “massive” rock mass (crushed stone). The quantitative asbestos determination in rocks is a very complex analytical issue: although techniques like TEM-SAED and micro-Raman are very effective in the identification of asbestos minerals, a quantitative determination on bulk materials is almost impossible or expensive and time consuming. Another issue is represented by the discrimination of asbestiform minerals (e.g. chrysotile, asbestiform amphiboles) from the common acicular – pseudo-fibrous varieties (lamellar serpentine, non-asbestiform amphiboles). Also, the correct sampling is of crucial importance, considering the size of rock fragments (sand, gravel or silt) and the geological variability within the quarry. In this work, more than 400 samples from the main Italian quarry areas were characterized by a combined use of XRD and an up to date sample preparation and quantitative SEM-EDS analytical procedure. The first step consists in the recognition of “green stones” (presence of serpentine and/or amphiboles) by means of macroscopic petrography (gravel) or XRD (sand, silt). The second step is represented by the “self-grinding” of the rock fragments (Los Angeles rattle test for gravel), and the quantitative SEM-EDS analysis of the “fine” fraction (< 2 mm). The third and last step consists in the complete grinding of the bulk sample and following SEM-EDS quantification. The results show a great variability for serpentinite-rich samples, with a wide asbestos concentration range; on the other hand, metabasites (prasinites, amphibolites) are generally less critical, because the presence of asbestiform amphiboles (especially tremolite - actinolite) is rarer and more occasional. As regards the samples deriving from alluvial and glacial deposits, the fibers tend to concentrate in the fine fraction (<2 mm).

How to cite: Cavallo, A.: Aggregates and naturally occurring asbestos: the need of a correct analytical approach, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3900, https://doi.org/10.5194/egusphere-egu2020-3900, 2020.

The event geological maps consist in innovative numerical maps that were just designed and produced for the first time, as part of the RGF (“French Geological Referential”) mapping program in the Pyrenees. Rocks acquire their mineralogical, structural and textural characteristics through a complex geological history reflecting successive stages of transformation (i.e. metamorphism, deformation, alteration…), so called “geological events”. Classical geological maps can only represent some of these events.  In the Pyrenean orogenic belt, which results from a polyphase tectono-metamorphic history over 600 Ma (from Precambrian to present), 3400 geological events were identified. Such geological events were classified by types (e.g. deposit, volcanism, intrusion, metamorphism, weathering, hydrothermal alteration…) and time periods. They were referenced into a database and associated to mapped features (120,000 polygons and lines), coming from a compilation of 60 geological maps at 1: 50,000 scale.

In the Pyrenees, Naturally Occurring Asbestos (NOA) mostly occur in specific lithologies such as ultrabasic, basic and intermediate plutonic rocks, and meta-limestones. These rocks may be affected by different metamorphic events (i.e. hydrothermal alteration, greenschist and/or HT-LP regional metamorphism, contact metamorphism). We performed a GIS treatment to produce a predictive map of potential NOA hosting lithologies. This treatment crosses lithological and selected geological event informations (e.g different metamorphic and alteration events).

Subsequent geological field investigations with associated sampling and laboratory analyses (combining optical microscopy, microprobe and SEM analyses) allowed us to identify and characterize fibrous and asbestiform mineralogical species. Results of this work particularly emphasize: (i) the importance of actinolite-asbestos in doleritic rocks, and (ii) the occurrence of fibrous actinolite/tremolite in different marbles and skarns. Finally, we present a 1: 50,000 scale map of potential NOA occurrences in the Pyrenees.

Conversely, field observations allowed us to improve both the lithostratigraphic and the event geological maps, in particular with the identification of geological domains where intense hydrothermal alteration was not previously mapped. All the data (maps of potential NOA occurrences, field observations and results of laboratory analyses) are stored in a geospatial database, partly accessible to the public. This work illustrates a possible use of geological event maps as a powerful innovative and predictivity tool. This approach will be useful in the context of the evolution of French regulations now imposing the search for asbestos before all types of works in natural environments.

How to cite: Cagnard, F., Lahondère, D., Le Bayon, B., Hertout, A., Baudin, T., Padel, M., Duron, J., and Stephan-Perrey, J.: The event geological maps: a new predictive tool to identify potential NOA (Naturally Occurring Asbestos) lithologies, Example from the Pyrenees (France)., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9453, https://doi.org/10.5194/egusphere-egu2020-9453, 2020.

Minerals defined as asbestos include only the fibrous varieties (length > 5 µm, diameter < 3 µm and length/diameter ratio > 3:1) and asbestiform (high tensile strength or flexibility) of serpentine and amphibole.

However, there are also prismatic varieties of amphiboles, which despite the same chemical composition, are not classified as asbestos. Their geometric ratio would fall within the concept of fiber, but the minerals are not asbestiform.

Starting from a fairly contradictory context, the goal of this work was to analyze the variables inherent the morphological, but above all, the clastogenic effect determined by exposure of both asbestiform and non-asbestiform amphiboles.

The asbestiform fibers (F3), and the other three samples containing non-asbestiform amphiboles (P1, P2, P3) were tested in A549 cells line. Each sample of fiber was inoculated in A549 cells at a concentration of 100 µg/ml for 48h. Experiments were assayed in triplicate and repeated twice. To evaluate the micronuclei number for each sample the fixed cells were dropped onto clean microscope slides, stained and observed by optical microscopy at 100X.

Obtained results showed a statistically significant increase (P < 0.05) of micronuclei in F3 exposed cells when compared to negative controls. Similar results were reported when A549 cells were exposed with non-asbestiform amphiboles P2. No significant increase of micronucleated cells was observed after exposure of cells line at samples P1 and P3.

Moreover, to investigate the effect long-term triggered after 24h post fiber exposure of the medium inoculated cells were replaced with fresh culture medium and the cultures were grown for 72h. Albeit a prolonged contact of the F3 and P3 fibers resulted in a statistically significant increase (P < 0.01) of the micronuclei, no increase was reported for P2.

These results indicate that the contact of non-asbestiform amphiboles in vitro, can determine a genetic disorder, a necessary step in the cancer development. However, the kinematic of processes and the bearing of results are to be further clarified. For this purpose, the same starting materials are presently tested to determinate the transformation efficiency in no-tumoral cells and will be analyzed the different pathway involved in the etiopathogeneses of diseases trigger by inhalation of fiber.

How to cite: Militello, G. M., Gaggero, L., Sanguineti, E., Yus González, A., and La Maestra, S.: Can non-asbestiform amphibole fibers trigger carcinogenesis mechanisms?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18420, https://doi.org/10.5194/egusphere-egu2020-18420, 2020.

The presence of Naturally Occurring Asbestos (NOA) is one of the greatest danger during excavations and tunneling.  The most important instrument for the NOA content prediction is the geological model.

As part of the consultancy provided in the works of the "Terzo valico dei Giovi" which includes the excavation of numerous tunnels in areas potentially affected by rocks containing asbestos, the case study of the tunnel called "Castagnola" is illustrated. The opera is the new high velocity railway connection between Genova and Milano and the case study is located in the Piedmont southern area near Fraconalto (AL).

The “Castagnola” tunnel area is characterized by greenish - reddish rocks metabasalt covered by recent grey shales in the upper part of the area; it refers to the ophiolitic Figogna Unit, elongated in a north-south direction, which belongs to Sestri-Voltaggio Zone.

Starting from geological sections and thanks to surface investigation and core drilling, an effective geological model was built.

This study highlights how, during the progress of the works, situations other than the forecast geological model are encountered. It also highlights the importance of the environmental monitoring of the airborne fibers dispersion inside the tunnel, which has proved extremely effective even in the presence of low asbestos content in the excavated rock.

Moreover, this study describes the trends in asbestos content in the material excavated during the route of the tunnel in comparison with the concentration of airborne fibers. Furthermore, the management of the asbestos problem, from the abatement of dust to the excavation and storage methods and the installation of efficient technologies such as an aspirating ventilation system already successfully tested in a previous excavation phase, are presented.

How to cite: Baietto, O., Amodeo, F., Vitaliti, M., Parisi, G., Scuderi, A., and Marini, P.: Dealing with asbestos presence in tunnel excavation: the Castagnola case study and the importance of the geological model, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17365, https://doi.org/10.5194/egusphere-egu2020-17365, 2020.

Over the last decades, rocks containing Naturally Occurring Asbestos (NOA) have been widely studied by many authors with the aim of determining 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. Indeed, the size and geometric shape ratios of asbestos chrysotile fibres can be subjected to change, thus leading to the misevaluation of asbestiform fibre findings. In this frame, our study aims to determine the characteristics of the veins that form in serpentinite (i.e. shape) and their infill (i.e. size of fibres), without grinding and/or particle size reduction.

To obtain this ambitious goal, 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. In the specific case, we analyzed a representative set of veins and fibrous chrysotile that fills the veins, taken from massive serpentinite outcrops (Southern-Italy; Bloise and Miriello, 2008). The non-destructive SR-μCT technique allowed to identify respirable chrysotile fibres (regulated asbestos) within the serpentinite matrix and to reconstruct the 3D structures of infill chrysotile asbestos fibres as well as other phase, whose structures were not resolvable with PLM, SEM or EPMA. Moreover, due to differences in chemical composition between veins and matrix, the obtained data enabled 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 (Bloise et al., 2019). The results proved that SR-μCT is a valuable and promising technique for analyzing asbestos chrysotile that fills the veins within massive serpentinite. The 3D images of veins may help to identify NOA contained within serpentinite rocks.

References:

Bloise, A., Miriello, D., 2018. Multi-analytical approach for identifying asbestos minerals in situ. Geosci. 8 (4), 133. https://doi.org/10.3390/geosciences8040133.

Bloise, A., Ricchiuti, C., Lanzafame, G., Punturo, R., 2019. X-ray synchrotron microtomography: a new technique for characterizing chrysotile asbestos, Sci. Total Environ. https://doi.org/10.1016/j.scitotenv.2019.135675

How to cite: Ricchiuti, C., Bloise, A., Lanzafame, G., and Punturo, R.: Synchrotron X-ray imaging for characterizing chrysotile asbestos, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-343, https://doi.org/10.5194/egusphere-egu2020-343, 2020.

Erionite is a well known carcinogenic fibrous zeolite being one of the most carcinogenic mineral fibre (IARC, 1987). In the last years other fibrous zeolites, such as offretite and ferrierite, assumed a growing interest in the scientific community, because of their probably carcinogenic effects to human after inhalation (Mattioli et al., 2018; Gualtieri et al., 2018).

The toxicity of these minerals is mainly defined by two important parameters: biodurability and biopersistence. Solubility plays a key role on these parameters; however, to the best of our knowledge, the experimental determination of the solubility of erionite and offretite is still missing. The lack of these data for natural zeolites, even in the most simple system (i.e. water), represents a severe limitation for the understanding of the complex interaction with the biological environments. The aims of this study is to be a starting point for further detailed studies on the dissolution kinetics of zeolites. Our experimental setup for low temperature kinetic studies could allows to figure out (I) the behaviour in pure water and then (II) the effect of inorganic and organic additives (e.g. in Simulated Lung Fluids). The assessment of the individual role of each component is fundamental to better understand the observed processes, and could be a starting point for the comprehension of the risks associated to human health.

Natural samples of erionite, offretite and stellerite (more abundant zeolite used as reference material) were used to perform dissolution experiments, at 25° C, to assess their aqueous solubility under the effect of atmospheric CO₂ concentration.

To obtain a relatively homogeneous crystal particle in the range 64 µm - 250 µm, the natural crystals were ground and sieved. The selected fraction was added to ultrapure H₂O (previously equilibrated with air for 30 minutes under stirring, i.e. in equilibrium with atmospheric CO₂ at pH 5). The dissolution process was followed over time with a conductivity probe equipped on a Metrohm OMNIS system. After several hours (days) under vigorous stirring (a floating stirrer was used to avoid a milling effect on the crystals), the samples were filtrated and the amount of Ca, Na, K, Mg, Al and Si was determined by ICP-OES (Agilent Varian, 700 ES). The powders were characterized before and after the interaction period. X-ray powder diffraction was used for the mineralogical characterization. The morphological characterization of the grains and the determination of the elemental formula were obtained by means of SEM-EDS and EMPA, respectively.

IARC. 1987. IARC Monographs on the Evaluation of the Carcinogenic Risk to Humans; Overall Eval. Carcinog. Updating IARC Monographs Vol. 1 to 42; IARC: Lyon, France.

Mattioli, M., Giordani, M., Arcangeli, P., Valentini, L., Boscardin, M., Pacella, A. and Ballirano P. 2018. Prismatic to Asbestiform Offretite from Northern Italy: Occurrence, Morphology and Crystal-Chemistry of a New Potentially Hazardous Zeolite. Minerals, 8, 69.

Gualtieri, A.F., Gandolfi, N.B., Passaglia, E., Pollastri, S., Mattioli, M., Giordani, M., Ottaviani, M.F. Cangiotti, M., ... and Gualtieri, M. L. 2018. Is fibrous ferrierite a potential health hazard? Characterization and comparison with fibrous erionite. American Mineralogist, 103(7), 1044-1055.

How to cite: Giordani, M., Di Lorenzo, F., Mattioli, M., and V. Churakov, S.: Erionite, Offretite and Stellerite: Solubility Assay, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11324, https://doi.org/10.5194/egusphere-egu2020-11324, 2020.

The naturally occurring asbestos (NOA) and naturally occurring of asbestiform minerals non asbestos classified (NONA) in North Western Italian Alps is known since many years and described in a few papers (e.g., Belluso et al., 1995; ARPA Piemonte, 2008). Whereas the noxiousness due to professional exposure to asbestos is well known, there are few information dealing with natural environmental exposure as that occurring to general population living closeness to NOA (and NONA) in outcropped rocks.

The investigation of inorganic fibres content in urine may understand if people respired them in the latest period (from several days to some months: e.g., ATSDR, 2001).

In this study we present a case of a very high and abnormal content of tremolite asbestos detected in urine of a young girl during a survey of several toxic contaminants respired from young students in a Turin province school (NW Italy).

The absence of asbestos revealed by further investigation carried out in urine sample of girl’s parents and in other samples from the girl, showed that the high asbestos content previously detected was due to an exposure occurrence limited in time and related only to the girl.

The investigation carried out on the lifestyle of the girl in the year preceding the urine analysis allowed to suppose that the detected high content of tremolite asbestos might be due to a specific environmental exposure. Indeed, the girl spent a holiday period away from her habitual home, where there were excavation works in NOA rocks spotty containing important amount of tremolite asbestos. Therefore, the asbestos detected in the urine is probably connected to those dispersed from NOA rocks.

This finding focuses on the need to evaluate the risk of asbestos air dispersion from NOA rocks before carrying out excavation works.

ARPA PIEMONTE (2008) Amianto naturale in Piemonte. Agenzia Regionale per la Protezione Ambientale del Piemonte, ARPA Piemonte, Ed. L’Artistica Savigliano (CN), I

ATSDR, Agency for Toxic substances and Disease Registry (2001). U.S., Department of Health and Human Services, Public Health Service. Atlanta, GA, USA

BELLUSO E, COMPAGNONI R, FERRARIS G. (1995) Occurrence of asbestiform minerals in the serpentinites of the Piemonte Zone, Western Alps. In: Giornata di studio in ricordo del Prof. Stefano Zucchetti, Politecnico di Torino, 57-64. Ed. Politecnico di Torino, I

How to cite: Belluso, E. and Capella, S.: High tremolite asbestos content in urine related to dispersion from NOA rocks: a case study, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5730, https://doi.org/10.5194/egusphere-egu2020-5730, 2020.

Water pollution by asbestos may result from anthropogenic sources, such as water passing in cement-asbestos aqueduct pipes, or natural sources. Referring to this second case, pollution could be due to the flow of superficial water or groundwater into naturally occurring asbestos (NOA) in rock formations like green stones and serpentinites.

Asbestos-bearing rocks weathering is the principal natural cause of fibres water-dispersion. Despite the abundant occurrence of NOA rocks where water can flow (underground and superficially) in the North-Western part of the Alps, a few is known about the mechanism of fibres release in water and the correlation with the geolithological and hydrogeological characteristics of the area.

Moreover, the knowledge on the eventual noxiousness of waterborne fibres have still to be deepened: in fact, they can come into contact with human being as airborne fibres after water vaporization, or by ingestion, especially if fibres are present in drinking water. While a lot is known about disease caused by airborne asbestos fibres high-dose respiration, not enough has been yet comprehended about potential noxiousness of fibre ingestion. Following some in vivo studies, US-EPA (United States Environmental Protection Agency) defined a maximum contaminant level of 7x10⁶ ff/l in drinking water, but this limit is not fully shared by the whole scientific community.

Against this background, it has become fundamental to clarify the main aspects related to waterborne fibres, in particular their natural occurrence in water and their transportation due to water flowing into NOA. Consequently, decision has been made to conduct a study on the former chrysotile mine of Balangero, in Piedmont (Italy), which was selected as a reference case study for its great significance in the North-Western Alps context. The case study was developed in collaboration with R.S.A. s.r.l., the company that is in charge of the site remediation.

A sampling and analysis campaign regarding the superficial hydrographic network of the area was settled: 5 different sampling points were selected, 2 of them inside the principal site perimeter and 3 in the villages situated downstream of the site. They have been monitored for about one year, to evaluate the seasonal variability.

The main aims of the research are:

• the evaluation of asbestos concentration in term of number of fibres per liter (ff/l);
• the correlation between the concentration variability and the precipitation pattern over the four seasons;
• the evaluation of asbestos concentration defined as mass per liter (pg/l), depending on fibres dimension;
• the study of fibres characteristics, such as their dimension, morphology and chemical composition;
• the study of a possible correlation between asbestos concentration in pg/l and ff/l;
• the potential presence of fibres bundles or aggregates which can constitute a problem in the evaluation of the asbestos concentration, in particular for the correlation between ff/l and pg/l.

Finally, an attempt to relate the number of waterborne fibres to those that can eventually be released in air is still ongoing.

How to cite: Avataneo, C., Belluso, E., Bergamini, M., Capella, S., De Luca, D. A., Lasagna, M., and Turci, F.: Waterborne Naturally Occurring Asbestos: a case study from Piedmont (NW Italy), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19615, https://doi.org/10.5194/egusphere-egu2020-19615, 2020.

As we continue to investigate the asbestos-forming minerals and their associated geology as they occur in North America, we have found that subtle variations can make the standardization of what is and what is not asbestos more difficult. On the other hand, some geochemical trends recently observed have given us significant insight into what we can expect in the ground, which we hope will lend much-needed information to medical investigators to better understand the relationship of mineral morphologic and chemical differences and the ramifications to human health for those potentially exposed. In efforts to understand why certain minerals form in the asbestiform habit, mineralogists still cannot fully explain the cause-and-effect of this phenomenon. Although we know that there are chemical variances and pressure or temperature regimes that are conducive to the formation of asbestos, a complete and absolute picture of how and why amphibole forms fibers, or serpentine forms chrysotile scrolls remains elusive. Research indicates however that there are two primary ways that sheet silicates compensate for the fundamental misfit between their tetrahedral silica layers (T) and their octahedrally-coordinated cation layers (O) that is by either tetrahedral rotation /stretching or by bending or modulation of the layers in concert. Rotation or stretching occurs in both the 1:1 layer silicates (T-O) such as serpentines, and the 2:1 phyllosilicates (T-O-T) such as vermiculite or talc. The other primary means of misfit compensation is structural bending, with the obvious examples of antigorite or chrysotile. Although it was originally hypothesized as early as the 1950s that this curving or bending of the sheet structure was entirely due to the T-O misfit, more recent research points to the importance and variances of hydroxyl bonding in the chrysotile structure. A secondary mode of compensation for the fundamental misfit is by the addition or subtraction of silica tetrahedra or octahedral cations in modulated fashion, which affects the overall chemistry of the mineral as a whole. In polysomatic hydrous biopyriboles we see the importance of hydration alteration reactions in the transformation of chain zippers. Thusly, a wide variety of intergrowth microstructures appear in Mg-rich 1:1 modulated layer silicates, analogous to the hydrous biopyriboles as is common intimate intermixing in a polysomatic series. It is therefore common that the means by which all of our regulated asbestos minerals form is through the combined action of T-O misfit compensation and the action of water in the crystallizing or re-crystallizing process. 

How to cite: Fitzgerald, S.: Asbestiform anthophyllite, tremolite, and related fibrous amphibole chemistry, both as primary and secondary mineralization in metamorphic facies in asbestos occurrences in North American deposit comparisons, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1205, https://doi.org/10.5194/egusphere-egu2020-1205, 2020.

The widespread concern on the environmental hazards and public health issues related to exposure to respirable dusts from naturally occurring asbestos (NOA) in principle should also apply to deposits of mineral fibres other than the currently regulated six asbestos minerals. Recent studies highlight that glaucophane can assume a fibrous habit resembling the regulated amphibole asbestos minerals. Glaucophane, sometimes occurring in a fibrous habit, is a major mineral component of blueschist rocks of the Franciscan Complex, USA. Recently, fibrous blueschist occurrences within the Franciscan Complex were being excavated in California for construction purposes (e.g., the Calaveras Dam Replacement Project) and concern existed that the dust generated by the excavation activities might potentially expose workers and the general public to health risks. For this reason, fibrous glaucophane (Gla) was considered to represent a potential health hazard as NOA by the dam owner, the San Francisco Public Utilities Commission, though an evaluation of the potential health hazard of this mineral fibre was not mandatory per local state and federal regulations. To fill this gap, the potential toxicity/pathogenicity of Gla from the Franciscan Complex has been assessed using the fibre potential toxicity model (FPTI) model and specific in vitro toxicity tests. FPTI is an analytical tool to predict the toxicity/pathogenicity of minerals fibers, based on physical/chemical and morphological parameters that induce biochemical mechanisms responsible for in vivo adverse effects. This model delivers an FPTI index aimed at ranking the toxicity and pathogenicity of a mineral fibre. Compared to asbestos minerals, the FPTI of Gla is considerably higher than that of chrysotile, comparable to that of tremolite and lower than that of crocidolite. Biological responses of cultured human lung cells (THP-1 and Met-5A) following 24 and 48h of exposure to different doses of Gla (25, 50 and 100 µg/mL), have been determined by Alamar Blue viability, Extra-cellular lactate dehydrogenase (LDH) and Comet assays. Generation of reactive oxygen species (ROS) has been evaluated performing the luminescent ROS-Glo™ assay. Crocidolite UICC asbestos (100 µg/mL) was also tested for comparison. Results of in vitro tests showed that Gla may induce a decrease in cell viability and an increase in LDH release in tested cell cultures in a concentration dependent mode. Overall, the rank of the investigated fibres in increasing order of cytotoxicity is: Gla (25 μg/mL) < Gla (50 μg/mL) < crocidolite (50 μg/mL) < Gla (100 μg/mL). For both the cells lines, Gla was able to induce DNA damage. Moreover, it was found that Gla can induce the formation of ROS. The chemical-structural features and biological reactivity of Gla confirm that this mineral fibre is a toxic agent. Although Gla induced lower toxic effects compared to the carcinogenic crocidolite, the inhalation of its fibres may be hypothetically responsible for the development of lung diseases. For a conclusive understanding of the mechanisms of the cellular/tissues responses to fibrous glaucophane, in vivo animal tests should be performed and compared to our outcome to stimulate a critical evaluation and a classification by the International Agency for Research on Cancer (IARC).

How to cite: Di Giuseppe, D., Gualtieri, A., Zoboli, A., Filaferro, M., Vitale, G., Avallone, R., Bailey, M., and Harper, M.: Assessment of the potential health hazard of fibrous glaucophane, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5356, https://doi.org/10.5194/egusphere-egu2020-5356, 2020.

Non-occupational (environmental) exposure to naturally occurring asbestos (NOA) represents a potentially important source of risk for human health in several parts of the world. Chemical reactivity of fibres surface is one of the most relevant physical-chemical property to asbestos toxicity and is commonly associated to the presence of Fe at the surface, and in particular to its coordination and oxidation state. However, no detailed information is still available about dependence of chemical reactivity on surface iron topochemistry, which is the basis for defining structure-activity relationships. In this work the chemical reactivity of two amphibole asbestos samples, UICC crocidolite from Koegas Mine, Northern Cape (South Africa) and fibrous tremolite from Montgomery County, Maryland (USA), was investigated after sample heating up to 1200 °C. Ex-situ X-ray powder diffraction (XRPS and the Rietveld method), scanning (SEM) and transmission (TEM) electron microscopy were used for characterizing the mineral fibres before and after the thermal treatment. In addition, thermal stability of the of the amphibole asbestos was analysed in-situ by TG/DSC. Two conventional target molecules (H₂O₂ and HCOO^-) and the DMPO spin-trapping/EPR technique were used to measure the radical activity of both pristine and thermal treated samples. Results show that, after thermal treatment, both amphibole asbestos are completely converted into hematite, cristobalite and pyroxene, still preserving the original fibrous morphology (pseudomorphosis). Notably, in spite of the thermal decomposition, the heated samples show a radical production comparable to that of the pristine ones.

How to cite: Ballirano, P., Pacella, A., Tomatis, M., Turci, F., Viti, C., and Bloise, A.: Chemical reactivity of thermal treated naturally occurring amphibole asbestos, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10801, https://doi.org/10.5194/egusphere-egu2020-10801, 2020.

This study analizes the dissolution reactions, and the corresponding surface modifications, of two amphibole asbestos incubated for 1, 24, 48, 168 and 720 h in a modified Gamble’s solution at pH 4.5. The investigated samples are UICC crocidolite from Koegas Mine, Northern Cape (South Africa), and fibrous tremolite from Montgomery County, Maryland (USA). Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) was used to monitor the ion release into solution, X-Ray Photoelectron Spectroscopy (XPS) was performed to unveil the chemistry of the leached surface, and High Resolution Transmission Electron Microscopy (HR-TEM) was exploited for monitoring the structural modifications of the fibres.

An incongruent cation mobilization was observed in both samples. Fe mobilization was detected only in UICC crocidolite, due to the occurrence of Fe-bearing accessory phases in the sample (siderite, iron carbonate, and minnesotaite, an iron-bearing phyllosilicate). Notably, tremolite lifetime is shown to be roughly ten times that of UICC crocidolite under the same experimental conditions. This result agrees with previous dissolution studies at pH 7.4 indicating a higher dissolution and surface alteration for UICC crocidolite with respect to tremolite.

How to cite: pacella, A., nardi, E., montereali, M. R., fantauzzi, M., rossi, A., viti, C., and ballirano, P.: Dissolution of amphibole asbestos in modified Gamble’s solution at pH 4.5: a combined ICP-OES, XPS and TEM investigation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11407, https://doi.org/10.5194/egusphere-egu2020-11407, 2020.

Soils contaminated with asbestos, whether of natural origin or deriving from anthropogenic pollution, can have very different dimensional, chemical and humidity characteristics.

The legal limit that allows to define an asbestos contaminated soil is a concentration of 1000 mg / kg of asbestos fibers, as per DLGS 152/2006. The analytical methods suggested in Italy by regulation (DM 6/09/94) for the determination of asbestos content are Diffrattometry (XRD) and  Fourier Transform Infrared (FTIR), methods that do not allow to distinguish the fibrous material and secondly Scanning Electron Microscopy (SEM). The Phase Contrast Optical Microscopy (PCOM) is considered a methodology only useful for a qualitative analysis for it low rilevability index (0,1 mm in respect of   for SEM and    for XRD and FTIR).

The goal of this study is to describe the cheap and quick soil analysis methodology used in the Asbestos laboratory of DIATI Politecnico di Torino where also the representativeness of the analysed quantity of material is considered.

When the sample is an incoherent soil, sieving (at 0.6 - 0.3 – 0.150-0.075 mm) after drying is carried out. The asbestos fibers eventually present in the classes >0.6 mm and 0.6-0.3 mm, that are visible with a low magnification (5-10 x), can be recovered by flotation and weighted after drying. The quantitative analysis of the classes 0.3-0.075 is perfomed by means of PCOM, measuring the dimensions of the fibers, hipotyzing the third dimension equal to the width and calculating the weight knowing the density of the asbestos fiber observed.  .The presence of asbestos in the finer particle size class can be verified by SEM, but is the asbestos content in the other particle size classes is high the value obtained for the finer class is generally found to be irrelevant to the final result.If the initial sample has a very fine particle size, it is homogenized by grinding and is prepared for reading under the SEM by depositing a known quantity on a polycarbonate membrane. The results thus obtained are referred to the analysis of at least 100 g of material.

The reliability of the technique has been verified by participating in interlaboratory circuits.

How to cite: Zanetti, G., Marini, P., and Baietto, O.: Methods for the analysis of asbestos in incoherent soils, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20129, https://doi.org/10.5194/egusphere-egu2020-20129, 2020.

Asbestos is a commercial term which refers to six minerals that crystallize as fibrous bundles made of very thin and easily separable fibrils. Asbestos fibers have been exploited for a long time and voluntary added in a very large set of manufactured products. In France, asbestos is prohibited since an official decree published in 1997 that prohibits the manufacture, processing, sale and import of asbestos. The asbestos ban has been the subject of an European directive published in 1999. 
Following this ban, a standard was defined in order to specify the sampling, preparation and identification methods for asbestos fibers in samples of commercial origin (ISO 22262-1). For natural materials, no specific analytical protocol is currently defined in France. Searching for asbestos in a rock sample, the commonly used protocols require the reduction of the sample, the grinding of a sub-sample (1 to 2 g) and its calcination in order to eliminate organic matter, then an acid attack to dissolve some constituents (calcite, gypsum). The final test portion (~ 20 mg) is mixed in water, stirred using ultrasound, filtered through a metallized membrane and covered with a new layer of carbon before it can be examined using a transmission electron microscope.
The protocols currently used are long and complex and require the grinding of the sub-sample. This grinding operation is a critical step because it can lead, starting from non-asbestiform minerals, to the artificial formation of more or less fine and elongated fibriform particles (cleavage fragments), quite similar in some cases to asbestos fibers. Grinding is therefore an operation liable to affect the quality of the final diagnosis.
The new protocol presented here was built with the aim of developing an analytical approach specific to coherent rock samples. This protocol does not involve the grinding of the sample and allows the in-situ morphological and chemical characterization of fibrous minerals. It is based on the use of combined analytical techniques (MOLP, EPMA, FESEM-EDS, FIB-SEM, and confocal RAMAN in SEM) from a single support corresponding to a polished thin section. This protocol allows to observe the natural morphologies of the fibers, to measure their dimensions, to characterize the relationships between fibers and the other mineralogical constituents while preserving the texture of the rock and to acquire precise chemical analyzes of the fibers. It also overcomes problems related to the grinding of the sample and the formation of cleavage fragments. This protocol has been tested through the study of several types of massive rock samples. It provides a representative and reliable in-situ diagnosis of the initial state of the fibers in solid rocks.

How to cite: Lahondère, D., Wille, G., Schmidt, U., Silvent, J., Duron, J., and Duée, C.: Morphological and chemical characterization of asbestos fibers in solid rocks: Towards an in-situ and combined analytical approach, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13773, https://doi.org/10.5194/egusphere-egu2020-13773, 2020.

The quantification of asbestos in ophiolitic rocks is of particular importance in the management of soil and rock excavated in civil works and materials from quarry exploitation.

In Italy, a well-described quantitative method is currently available taking advantage of the high resolution of scanning electron microscopy (SEM) and the mineral discrimination provided by energy dispersion spectroscopy (EDS) (Italian Ministerial Decree of 06/09/1994). The method provides a limit of detection of ca. 4-10 ppm and delivers quantitative results for asbestos content higher than 100 ppm. Conversely, a guide for on-field sampling and laboratory sample milling / preparation is still required, to correctly define the quantities of materials of variable geometric dimensions and weight to be sampled following a representative approach. The development of a proper sampling protocol will define the minimum volume of material that is required to correctly represent an asbestos-bearing soil/rock.

The work aims to introduce a structured composite sampling and processing protocol, to reduce data variability and increase sample representativeness for a specified volume of material under investigation.

The protocol is designed to obtain one single aliquot for SEM-EDS quantitative analysis (ca. 10 g) that has all the constituents in the same proportion with a known grade of accuracy and to minimize sample preparation time.

Variability in measured asbestos concentration in ophiolitic rocks between discrete samples is due primarily to the texture of rocks and heterogeneity in the distribution of asbestos. To consider the heterogeneous distribution of asbestos, a simulation of size distribution of the material after laboratory size reduction (crushing and grinding) as a function of operating parameters was obtained. It was studied the influence of some parameters, specifically linked to ophiolitic rocks, such as: particles shape factor, granulometric factor, mineralogical factor, asbestos liberation factor, and maximum particle size on the representativeness of the subsamples.

The methodology provides reasonably unbiased, reproducible estimates of the mean concentration of asbestos in the specified volume of material.

How to cite: Belardi, G., Trapasso, F., Tempesta, E., Passeri, D., Paciucci, M., Botta, S., Avataneo, C., Barale, L., Piana, F., and Turci, F.: Sampling protocol, preparation scheme and error evaluation for SEM-EDS quantitative analysis of asbestos in ophiolitic rocks, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21950, https://doi.org/10.5194/egusphere-egu2020-21950, 2020.

In this study, two types of natural asbestos-like actinolite occurrences were sampled in order to understand their tectonic and metamorphic signification. Studied rocks were collected within two Variscan ophiolitic formations (Tréogat and Pont de Barel Formations, South Armorican Massif, Western France), mainly composed of amphibolites, and which recorded amphibolite to greenschist facies metamorphism. In these localities, the natural asbestos-like actinolite occurrences are closely related with the development of tectonic structures such as extension veins, tension gashes, σ and δ-type boudins. Field and petrostructural studies together with optical microscope, SEM and electron-microprobe analyses (EPMA) allowed to link early steps of the retrograde deformation event, during which acicular hornblende crystallizes in extension veins showing fuzzy boundaries or in hosting rock, with the late step of the same deformation event, during which hornblende is downgraded into asbestos-like actinolite synchronous with felsic melt circulation and tectonic structures opening. Field and microtectonic observations point to a sinistral strike-slip shearing for Pont de Barel formation and to a sinistral transtensive shearing for the Tréogat formation, which is consistent with the late regional variscan exhumation of the South Armorican Terrane.  SEM observations show that asbestos-like actinolite originate from hornblende crystallographic plan fragmentation, starting first along the (110) plans and continue both along the (100) and (110) plans. EPMA analyses show that Na-Al-Si metasomatism is associated with this fragmentation. Temperature estimates of chlorite crystallization after hornblende are around 300°C for the Tréogat Formation and 200°C for the Pont de Barel Formation, suggesting that amphibole fragmentation can occur over a wide temperature range. Additionally, Principal Component Analysis was performed using crystallographic sites distribution. Results show a clear correlation between actinolite Si(T) and hornblende Al(T), Al(C) and Na(A) crystallographic sites, suggesting that asbestos-like actinolite after hornblende fragmentation is rather due to a decrease of pressure within the tectonic structures, as Al in amphibole is pressure-dependent. This decrease could be due to the fluid pressure, which is supra-lithostatic during tectonic structures opening.

How to cite: Aertgeerts, G., Lahondère, D., Triantafyllou, A., Lorand, J.-P., Monnier, C., and Bouton, P.: Asbestos-like actinolite crystallization during late regional variscan exhumation in the South Armorican Massif (France), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8001, https://doi.org/10.5194/egusphere-egu2020-8001, 2020.