Chrysotile asbestos in serpentinite quarries: a case study in Valmalenco, Central Alps, Northern Italy

From field analysis to nanostructural investigation: A multidisciplinary approach to describe natural occurrence of asbestos in view of hazard assessment

The environmental impact of natural occurrences of asbestos (NOA) and asbestos-like minerals is a growing concern for environmental protection agencies. The lack of shared sampling and analytical procedures hinders effectively addressing this issue. To investigate the hazard posed by NOA, a multidisciplinary approach that encompasses geology, mineralogy, chemistry, and toxicology is proposed and demonstrated here, on a natural occurrence of antigorite from a site in Varenna Valley, Italy. Antigorite is, together with chrysotile asbestos, one of the serpentine polymorphs and its toxicological profile is still under debate. We described field and petrographic analyses required to sample a vein and to evaluate the NOA-hazard. A combination of standardized mechanical stress and automated morphometrical analyses on milled samples allowed to quantify the asbestos-like morphology. The low congruent solubility in acidic simulated body fluid, together with the toxicity-relevant surface reactivity due to iron speciation, signalled a bio-activity similar or even greater to that of chrysotile. Structural information on the genetic mechanism of antigorite asbestos-like fibres in nature were provided. Overall, the NOA site was reported to contain veins of asbestos-like antigorite and should be regarded as source of potentially toxic fibres during hazard assessment procedure.

Size characteristics of asbestiform fibers in lung tissue of animals that grazed in areas rich in ophiolitic outcrops in Central Calabria (Southern Italy)

In Calabria (Southern Italy) naturally occurring asbestos (NOA) mainly occurs in the ophiolitic sequences cropping in the Mount Reventino area. The most common type of asbestos detected was the amphibole tremolite; fibrous antigorite and minor chrysotile were also found. The development of asbestos-related diseases depends on, among other things, the morphological characteristics of fibers, length and width, affecting the durability of asbestos fibers in the lung. In this work fifteen lung samples of sheep, goats and wild boars, grazing around the Mount Reventino area were collected and asbestos fibers analysed. Observed fibers (357), of which 97 % were tremolite and 3 % antigorite fibers, were grouped according to species, grazing area and age of the animals. The aim of this work was to highlight any differences among the groupings and to compare our size results with data in literature related to exposed populations. Principal Component Analysis (PCA) highlighted a positive correlation between tremolite fiber length and width and revealed groupings in terms of animal age. The Kruskal-Wallis test showed statistically significant differences between fiber mean widths in young and old animals. 63 % observed asbestiform fibers were longer than 5 μm and 7 % of the fibers were longer than 20 μm (critical fiber length connected to the frustrated phagocytosis by the macrophage). Fibers conforming to the Stanton Hypothesis size (predictor of the carcinogenic potency of fibers) were 1 %. Our size parameters of fibers detected in the animal lungs were in fairly good agreement with literature data for human asbestos exposure to tremolite. These results confirmed that an animal-sentinel system could be used to monitor the natural background of the airborne breathable fibers exposure. In addition, the size correlation of animal-human breathed fibers could be useful to study their potential toxicity. Additional data are necessary for improving the agreement with human exposure data.

Impact of Naturally Occurring Asbestos on Asbestos Ban: Regulations and Experience of the Republic of Korea

This review examined the main issues debated in Korea regarding the production and use of materials containing naturally occurring asbestos (NOA) as impurities, and investigated the impacts of these debates on the asbestos ban, as well as the future implications. In Korea, incidents associated with the production and use of NOA-contaminated talc powders, construction rocks, serpentinites, and dolomite rocks raised public concern and led to accelerating the ban on asbestos. The main controversies concern policies on appropriate asbestos content limits, whether materials containing a trace amount of NOA should be banned, and the control of materials with high human exposure risk. To address recurring controversies, the implementation of preventive measures to manage elongated mineral particles and the use of transmission electron microscopy for more sensitive analysis need to be discussed, along with reaching social agreement on the controversial policies. To minimize the potential exposure to asbestos that may occur during the production and use of industrial minerals in the future, it is necessary to apply occupational exposure control measures and monitor the health effects of the relevant population groups. These national policies on NOA should be prepared based on close collaboration and discussion with policymakers, industry stakeholders, and related academic experts.

Portable Raman Spectrometer for In Situ Analysis of Asbestos and Fibrous Minerals

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

Environmental contamination by naturally occurring asbestos (NOA): Analysis of sentinel animal lung tissue

Ophiolites are known sources of naturally occurring asbestos (NOA). In Calabria (Southern Italy) NOA are mainly concentrated in the ophiolitic sequences cropping in the Mount Reventino area, in the southern part of the Sila massif, and along the Coastal Chain. The most common type of asbestos identified in the rocks of these areas belongs to the tremolite-actinolite series. Another identified asbestiform mineral is fibrous antigorite belonging to the serpentine mineral group with a minor amount of chrysotile. The purpose of the present study is to evaluate the diffusion of natural asbestiform fibers from NOA using sentinel animals. Fifteen lung samples of sheep, goats and wild boars from Mount Reventino area and two from an area free from NOA were collected. The lung samples were subjected to anatomopathological examination and lung fiber burden analysis by electron microscopy. Abundant tremolite and few antigorite fibers were detected in the lung samples coming from the NOA area. No corpuscle of asbestos was observed. No fiber was found in the two lung samples of sheet from the area free from NOA. These concentrations of fibers per gram of dry weight of lung tissue (f/gdw) ranged from 10⁴ to 10⁶ f/gdw. The asbestos fibers detected in the lungs of the examined animals reflect the geological features of the areas where they grazed and lived. The anatomopathological analysis showed that 60% of the examined animals had macroscopic lesions affecting their lungs. The presence of tremolite fibers in the lungs confirms the diffusion of mineral fibers in the environment and the real advantage of using animal populations in the study areas.

Multi-Analytical Approach for Identifying Asbestos Minerals In Situ

An innovative and, as yet, untested approach is to analyze serpentinite and metabasite rocks containing asbestos using a portable multi-analytical device, which combines portable digital microscopy (p-DM), portable X-ray Fluorescence (p-XRF) and portable micro-Raman Spectroscopy (p-µR). The analyses were carried out in two inactive quarries of serpentinitic and metabasitic rocks from the Gimigliano-Mount Reventino Unit (Southern Italy) already characterized in previous studies, with the aim of testing the efficiency of these portable tools. In this study, a portable X-ray fluorescence analyzer was used to obtain the in situ rapid chemical discrimination of serpentinite and metabasite rocks. The characterization of outcropping rocks using portable devices enabled us to detect the presence of chrysotile and asbestos tremolite. The results obtained were consistent with the findings from previous research studies and therefore combining p-DM, p-XRF and p-µR could be a useful approach for discriminating asbestos contained in outcropping rocks, especially when sampling is prohibited or for field-based sampling.

Asbestiform minerals in ophiolitic rocks of Calabria (southern Italy)

Ophiolitic rocks cropping on Calabria territory, southern Italy, can hold asbestiform minerals potentially harmful for human health. The aim of this work was to detect the fibrous phases of ophiolites along the Coastal Chain of northern Calabria and southern part of the Sila massif. Above 220 massive samples were collected in the study areas and analyzed using optical and electron microscopy, X-ray diffractometry, and Fourier transform infra-red spectrometry. The main fibrous constituent belonged to tremolite-actinolite series followed by fibrous antigorite that becomes more abundant in the samples collected in Reventino Mount surroundings. Results highlighted that serpentinites samples mainly consisted of antigorite and minor chrysotile. Samples collected along the coastal chain of northern Calabria did not hold fibrous materials. The results will be useful for Italian natural occurrences of asbestos (NOA) mapping in order to avoid an unintentional exposition by human activity or weathering processes.

Airborne asbestos fibres monitoring in tunnel excavation

Tunnelling across ophiolitic formation with Naturally Occurring Asbestos (NOA) can release fibres into the environment, exposing workers, and the population, if fibres spread outside the tunnel, leading to increased risk of developing asbestos-related disease. Therefore, a careful plan of environmental monitoring is carried out during Terzo Valico tunnel excavation. In the present study, data of 1571 samples of airborne dust, collected between 2014 and 2016 inside the tunnels, and analyzed by SEM-EDS for quantification of workers exposure, are discussed. In particular, the engineering and monitoring management of 100 m tunnelling excavation across a serpentinite lens (Cravasco adit), intercalated within calcschists, is reported. At this chrysotile occurrence, 84% of 128 analyzed samples (from the zone closer to the front rock) were above 2 ff/l. However, thanks to safety measures implemented and tunnel compartmentation in zones, the asbestos fibre concentration did not exceed the Italian standard of occupational exposure (100 ff/l) and 100% of samples collected in the outdoor square were below 1 ff/l. During excavation under normal working conditions, asbestos concentrations were below 2 ff/l in 97.4% of the 668 analyzed samples. Our results showed that air monitoring can objectively confirm the presence of asbestos minerals at a rock front in relative short time and provide information about the nature of the lithology at the front. The present dataset, the engineering measures described and the operative conclusions are liable to support the improvement of legislation on workers exposure to asbestos referred to the tunnelling sector, lacking at present.