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.

How to cite: Petriglieri, J. R., Pacella, A., Barale, L., Leinardi, R., Tomatis, M., Ballirano, P., Piana, F., Huaux, F., Campopiano, A., and Turci, F.: An integrated general approach to assess the potential risk of outcrops contaminated by asbestos and asbestos-like minerals, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9589, https://doi.org/10.5194/egusphere-egu23-9589, 2023.

Elongate Mineral Particles of interest (EMPi) are asbestiform and non-asbestiform varieties of the six regulated asbestos minerals (actinolite, tremolite, anthophyllite, grunerite, riebeckite, chrysotile) and of four other mineral fibers (winchite, richterite, edenite, erionite) known as carcinogen for human. Material and airborne EMPi measurement protocols have been tested and used for a national exploratory campaign entitled Carto PMAi (EMPi Map). The aim of this French national project is to give relevant data on potential exposure of worker and public populations to EMPi and recommendations to the Ministries of Health, of Labor and of Environment. Therefore, they would be able to set up legal provisions proportionally to the risk,
in case of population exposure to EMPi. The “Carto” process that is also used for other campaigns, as for example for crystalline silica measurements, is based on single operating procedures, measurement monitoring and validation by scientific institutes. Here, are presented the measurement protocols that have been used to assess workers and public population to EMPi during the most emissive and the most frequent situations of the construction sector activities, i.e. in quarries producing aggregates for bituminous pavement and during earthworks.

How to cite: Léocat, E. and Deneuvillers, C.: Measurement protocols to assess exposure risk of workers and public population to Elongate Mineral Particle of Interest, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17574, https://doi.org/10.5194/egusphere-egu23-17574, 2023.

Erionite is a naturally occurring zeolite originating from hydrothermal alteration or diagenesis of volcanic rocks. Typically, the two main types of rock in which erionite occurs are basalt and tuff. Erionite generally displays a fibrous morphology, and as with asbestos fibre exposure, respirable fibrous erionite has been linked to cases of malignant mesothelioma. Notably, fibrous erionite appears to be comparable or even more carcinogenic than the six regulated asbestos minerals. The first health issues regarding erionite exposure were observed in Cappadocia (Turkey), and more recently, occupational exposure issues have emerged in the USA. The International Agency for Research on Cancer (IARC) has classified erionite as a Group 1 carcinogen. Nevertheless, undisturbed erionite fibres are not thought to pose a risk to human health. In New Zealand, erionite has been found in surface rock exposures at numerous locations throughout both the North and South Islands, including (from north to south) Kaipara, Auckland, Taupo Volcanic Zone, Banks Peninsula, and the Moeraki coast. Due to the carcinogenic nature of erionite, understanding the distribution and character of the mineral fibres in New Zealand is pivotal. This investigation into erionite in New Zealand is being undertaken using optical and electron microscopy, X-ray powder diffraction and Raman spectroscopy to identify erionite and other zeolites occurring alongside the mineral. Notable examples identified so far include woolly erionite in vesicles within rhyolitic rock in the Canterbury region of the South Island, and asbestiform erionite in the Waitakere Group Volcanics in the Auckland region, of the North Island. Further research is currently ongoing to further delineate the geological occurrence and characterise the mineralogy and chemistry of all erionite samples from New Zealand in an attempt to outline the crystal chemistry of erionite from New Zealand and the related environmental risk hazards.

How to cite: Patel, J. P., Brook, M., Gualtieri, A. F., Kah, M., and Hamilton, A.: New data on the geology and characteristics of erionite in New Zealand, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2917, https://doi.org/10.5194/egusphere-egu23-2917, 2023.

Antigorite occurs in several locations worldwide and is defined as the simple serpentine Mg₃Si₂0₅(OH)₄ polymorph that compensates for the silica tetrahedral layer (Si₂O₅ sheet) misfit with the octahedral brucite Mg(OH)₂ layer by regular structural undulation down the “b” crystalline axis. The chrysotile polymorph of the same chemistry compensates for the misfit in full rolls or scrolls along “b” axis, which can form fine fibres, and is the most common mineral in commercial asbestos. Chrysotile is therefore always asbestiform, but antigorite can exhibit a variety of crystalline habits in hand sample and the microscope, from massive, to platy, to bladed, and (occasionally) fibrous, but is not regulated as asbestos.

Here, we performed a multi-method study in order to characterize a highly fibrous asbestiform occurrence of antigorite from Rowland Flat, South Australia. In comparison to HSE Canadian chrysotile, we show that optical (PLM) and transmission electron microscopy (TEM) allows to distinguish this antigorite from chrysotile. Based on PLM analysis with CS dispersion staining, chrysotile is magenta parallel (ǁ) to the polarizer and exhibits blue perpendicular (Ʇ) colours while this antigorite exhibits gold to golden magenta ǁ and blue-magenta Ʇ colours (1.550 HD RI at 25^◦C). Also, we demonstrate SAED-TEM patterns for the two specimens to distinguish chrysotile “enrolled” crystal structure from the undulating antigorite structure, focusing on the highly characteristic [110] zone rel-rod streaking versus systematic repeats.

Scanning electron microscopy (SEM) images were collected to further investigate the asbestiform nature of the antigorite from Rowland Flat. We show that the dominant morphology of Rowland Flat antigorite is of microscopic laths that split into very thin needles. In order to further investigate the morphometric parameters of this fibrous antigorite, individual fibres were measured at 20,000-25,000x by TEM. We show that the majority of these structures meet or exceed WHO fibres criteria, display high mean aspect ratios, ranging from 20:1 up to more than 100:1, and display widths lower than 1 µm, which in the literature is definition for asbestos fibres.

Finally, our data indicate that the antigorite from Rowland Flat exhibits all characteristics of the asbestiform habit as defined in international standards (i.e., EPA/600/R-93/116), supporting the need for regulation of asbestiform antigorite as asbestos.

How to cite: Menini, A., Truong, B. H., and Fitzgerald, S.: Multi-method characterization of Asbestiform Antigorite from South Australia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3609, https://doi.org/10.5194/egusphere-egu23-3609, 2023.

Studies on naturally occurring asbestos (NOA) and on the relevant geo-environmental problems have been traditionally focused on metamorphic rocks (and, more recently, on magmatic rocks). Besides these 'primary' occurrences (i.e., those related to the in situ growth of NOA minerals), 'secondary', detrital NOA may occur in sediments, sedimentary rocks and soils derived from the erosion of 'primary' NOA bearing rocks.

The occurrence of detrital NOA in sediments and soils is increasingly recognized worldwide. However, a few studies exist that investigate the 'sedimentology of NOA', i.e., the mechanisms underlying the genesis, transport, deposition and post-depositional modifications of detrital NOA particles in the different sedimentary environments. A better understanding of these mechanisms would give us the tools to predict the presence and possible concentration of detrital NOA in sediments and sedimentary rocks.

The occurrence and distribution of detrital NOA within the Oligocene-Miocene succession of the southern Tertiary Piemonte Basin (NW Italy), will be investigated as a scientific development in the frame of the CARG project (Geological Mapping at 1:50,000 scale - sheet 195 Novi Ligure). This succession consists of stratigraphic units rich in ophiolite clasts and deposited in a variety of sedimentary environments, from continental to deep marine, thus representing an ideal study case.

How to cite: Barale, L., d'Atri, A., Petriglieri, J., Piana, F., and Turci, F.: Naturally Occurring Asbestos (NOA) in sedimentary rocks: state of the art and perspectives, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17589, https://doi.org/10.5194/egusphere-egu23-17589, 2023.

Environmental exposomes in the natural environment include silicate ash from volcanic eruptions and wind-blown mineral dust, both of which may promote lung disease if subjected to prolonged exposure. In order to develop strategies for risk mitigation in populations subjected to hazardous minerals in the environment, it may be useful to integrate mineral chemical composition with the three-dimensional particle characteristics (e.g. shape and surface characteristics) as a means to fully assess potential mechanisms of toxicity. In this contribution we show how a combination of confocal laser microscopy, a non-destructive technique capable of resolving true 3D geometry of PM₁₀ and PM_2.5 particles, with spectroscopic analysis, provides a novel and rapid way to assess the minero-chemical properties of potentially hazardous airborne material (Wertheim et al. 2017).

Initial results using samples from the 2021 La Palma volcanic eruption (volcanic silicate ash) show that volcanic particles (angular forms) increased pneumococcal adherence to A549 lung epithelial cells in vitro (Miyashita et al. 2022). Preliminary confocal images of airborne mineral dust originating in Saharan Africa and deposited on Tenerife during a sandstorm (Calima event, February 2020), show more rounded, mature particle shapes than volcanic ash, yet with clear variations in surface features. Hence we are investigating whether Calima particles could also affect pneumococcal adherence to lung cells in vitro.

Applying such a multidisciplinary approach combining results from different techniques may help to raise awareness of and prevent longer-term occupational hazards in populations such as the Canary Islands, where residents are at risk of multiple sources of exposure to both volcanic ash and inorganic dust.

References

Wertheim D, Gillmore G, Gill I, Petford N. High resolution 3D confocal microscope imaging of volcanic ash particles. Sci Total Environ. 2017 Jul 15;590-591:838-842. DOI: 10.1016/j.scitotenv.2017.02.230.

Miyashita L, Coldwell B, Wertheim D, Giddens R, Gill I, Petford N, Pérez N and Grigg J. La Palma Volcanic Ash Particles Increase Susceptibility to Pneumococcal Infection In Vitro. European Respiratory Journal 2022 60: 3163; DOI: 10.1183/13993003.congress-2022.3163

How to cite: Coldwell, B., Wertheim, D., Myashita, L., Gill, I., Crust, S., Giddens, R., Grigg, J., Pérez, N., and Petford, N.: Rapid minero-chemical classification of volcanic ash and inorganic dust at PM10 level: the longer-term effects of short-term hazards in the Canary Islands., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8091, https://doi.org/10.5194/egusphere-egu23-8091, 2023.

The literature indicates that jobs which involve cutting and rectifying or edge-grinding of ceramic tiles are potential sources of particulate matter (PM) and respirable crystalline silica (RCS) emissions. The European Union has recently included “jobs that involve exposure to respirable crystalline silica dust generated in a work process” as a carcinogen in the Directive that regulates exposure to carcinogens or mutagens at work (Directive 2004/37/EC and amendments). In general, ceramic tile production facilities have implemented different preventive and/or corrective measures (air extraction protocols, personal protective measures, etc.) to reduce workers exposure to PM. However, this activity may also be carried out in smaller-sized facilities, where sometimes the mitigation measures applied could have less efficiency, as well as by individuals applying tile floorings in residential areas, not always using the adequate personal protective equipment. The literature regarding this kind of exposures and their impact on the human health is scarce, a gap which this work aims to fill.

The objective of this work was to characterise the number and mass concentrations, RCS, chemical composition, morphology and in vitro toxicity of particles released during different ceramic tile-cutting operations. Experiments were carried out in a chamber with controlled ventilation and no infiltration from outside air, using on-line and offline aerosol instrumentation. Aerosol chemical composition was characterised using SKC PCIS impactors (PM0.25, PM0.5, PM1, PM2.5, PM10) and ELPI+ (0.006 μm to 10 μm). PM2 aerosols were sampled in liquid suspension using a Biosampler, and in vitro assessments were performed with a commercial A549 lung-cell line. Particle morphology was determined by SEM. The dust emitted during cutting operations was also analysed by ICP-OES and ICP-MS.

Release of coarse, fine and ultrafine particles, including nanoparticles, was evidenced during the experiments. Particle number concentrations were comparable during cutting of both types of materials, reaching on average 20.000-45.000/cm³ (1-min concentrations) of which 87% were smaller than 100nm. Peak respirable mass concentrations typically reached 30-50 mg/m³. The dust deposited during the cutting operations showed a similar baseline composition in terms of major components (e.g., SiO₂, Al₂O₃), while it differed regarding tracer elements (e.g., Zn) which could be due to the different body, glaze and decoration composition of the products studied. The chemical composition of aerosols released was consistent with that of the deposited dust. The content of crystalline silica in respirable dust was 10-20%, indicating that cutting operations may also produce high RCS levels. In vitro assessments (MTT assay) showed statistically significant differences between tiles, ranging between non-significant toxicity to moderate cytotoxicity for aerosols generated during the different cutting operations. Similar results were obtained for the generation of reactive-oxygen species (ROS).

Overall, it was concluded that tile cutting has potential to impact human health if exposures are not controlled. The experimental setup used in this work could be useful to characterise dust generation when different ceramic products are processed under controlled conditions.

How to cite: Moreno, V., Roldan, C., Bou, D., López-Lilao, A., Sanfélix, V., Viana, M., and Montfort, E.: Physico-chemical, mineralogical and toxicological assessment of inorganic dusts from tile-cutting operations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17540, https://doi.org/10.5194/egusphere-egu23-17540, 2023.

Crystalline silica (CS) is a well-known toxic particle that may cause severe pathologies including silicosis, lung cancer, and several autoimmune diseases. [1a,b] The hazard associated to crystalline silica is extremely variable and depends on some specific characteristics, including crystal structure and surface chemistry.[1c] In particular, a specific family of surface silanols, called nearly free silanols (NFS), has been recently related to the interaction mechanisms occurring between quartz particles and cell membrane components, which initiate the lung inflammatory reaction. [2] Even though this phenomenon has been studied for decades on quartz,  the research on other silica polymorphs was limited, also because of the relative low abundance of some polymorphs. The CS polymorphs, i.e., quartz, cristobalite, tridymite, coesite, and stishovite, share the SiO₂ stoichiometry and differentiate for crystal structure. [3] Thus, the different crystal lattices expose differently ordered hydroxyl group patterns at the crystal surface. We proved that the NFS occur and take part in the molecular bio-interactions, not only on quartz, but also on the other CS polymorphs. Five high-purity samples representative of the five CS polymorphs were fully characterized by XRPD, Scanning Electron Microscopy, and IR spectroscopy. When CS polymorphs were contacted with model membranes (red blood cells), all of them were able to disrupt cell membranes, except stishovite, which was the only polymorph without NFS. By thermally modulating the topochemistry of surface silanols, it was possible to show that the membranolytic activity of the CS polymorphs quantitatively paralleled the occurrence of NFS. This observations confirmed the central role of NFS in regulating the interaction of silica with biomembranes. In conclusion, these results put the surface characteristics of CS particles in the foreground with respect to the crystal habit and provide a comprehensive understanding of the molecular mechanisms associated with silica hazard and bio-minero-chemical interfacial phenomena. [4]

[1] a) KAWASAKI, H. 2015, Inhal Toxicol, 27, 363-77; b) IARC 2012, IARC monographs on the evaluation of carcinogenic risks to humans, Lyon, World Health 543 Organisation c). BORM, P. J. A., et al. 2018, Part. Fibre. Toxicol., 15, 23;

[2] PAVAN, C., et al., 2020, Proc Natl Acad Sci U S A, 117, 27836-27846.

[3] GUTHRIE, G. D. & HEANEY, P. J. 1995, Scand J Work Environ Health, 21 Suppl 2, 5-8.

[4] PAVAN. C., et al., 2023, accepted on Frontiers in Chemistry, DOI: 10.3389/fchem.2022.1092221.

How to cite: Bellomo, C., Escolano-Casado, G., Cananà, S., Tomatis, M., Leinardi, R., Mino, L., Turci, F., and Pavan, C.: Crystalline silica polymorph surfaces and nearly free silanols: occurrence and possible role in toxicity mechanisms, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8141, https://doi.org/10.5194/egusphere-egu23-8141, 2023.