Characterization of Fibrous Wollastonite NYAD G in View of Its Use as Negative Standard for In Vitro Toxicity Tests

Today, despite considerable efforts undertaken by the scientific community, the mechanisms of carcinogenesis of mineral fibres remain poorly understood. A crucial role in disclosing the mechanisms of action of mineral fibres is played by in vitro and in vivo models. Such models require experimental design based on negative and positive controls. Commonly used positive controls are amosite and crocidolite UICC standards, while negative controls have not been identified so far. The extensive characterisation and assessment of toxicity/pathogenicity potential carried out in this work indicate that the commercial fibrous wollastonite NYAD G may be considered as a negative standard control for biological and biomedical tests involving mineral fibres. Preliminary in vitro tests suggest that wollastonite NYAD G is not genotoxic. This material is nearly pure and is characterized by very long (46.6 µm), thick (3.74 µm) and non-biodurable fibres with a low content of metals. According to the fibre potential toxicity index (FPTI) model, wollastonite NYAD G is an inert mineral fibre that is expected to exert a low biological response during in vitro/in vivo testing.

Assessment of the potential health hazard of fibrous glaucophane

<p>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 (<em>e.g.</em>, 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 <em>in vitro</em> 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 <em>in vivo</em> 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, <em>in vivo</em> 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).</p>

Fibrous ferrierite from Lovelock, Nevada, USA

<p>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.</p>

Moisture performance of a new thermal insulation composite for interior application

The paper introduces prototypes of a new composite insulation product for interior application. The product consists of a standard mineral fibre insulation batt, which is wrapped in a combination of a thin fabric of moisture absorbing, capillary active material and vapour retarding membranes. The insulation composite has been tested with small samples in a laboratory setup and in an outdoor field test on a full-scale brick wall, and has so far shown promising results in comparison with other products. The paper describes the new insulation composite and the initial moisture tests that have been made with its constituents as well as results from the laboratory and field tests of its ability to prevent moisture accumulation.

Characterisation of fibrous ferrierite in the rhyolitic tuffs at Lovelock, Nevada, USA

Ferrierite is the name for a series of zeolite-group of minerals which includes three species with the same ferrierite framework (FER) crystal structure but different extra-framework cations. Recent studies have shown that ferrierite can exhibit a fibrous-asbestiform crystal habit and may possess the same properties as carcinogenic fibrous erionite. Characterisation of the ferrierite in and around a mine location will be helpful in assessing the potential for toxic outcomes of exposure in the mine and any local population.The zeolite-rich tuff deposit of Lovelock, Nevada, USA is the largest occurrence of diagenetic ferrierite-Mg. A previous survey reported that ferrierite hosted in these rocks displays a fibrous morphology. However, these observations concerned a limited number of samples and until now there has been little evidence of widespread occurrence of fibrous ferrierite in the Lovelock deposit.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 powder X-ray diffraction, scanning and transmission microscopies, micro-Raman spectroscopy, thermal analyses, and surface-area determination was applied.The results prove fibrous ferrierite is widespread and intermixed with mordenite and orthoclase, 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.

Yellow Nail Syndrome with Bilateral Pleural Plaques and Diffuse Pleural Thickening: A Mimic of Asbestos Related Disease

Yellow nail syndrome is a rare acquired condition of unknown aetiology associated with distinct nail discolouration/xanthonychia, pulmonary manifestations, and lymphoedema. Pleural plaques and diffuse pleural thickening are typically, although not exclusively, recognised as markers of prior commercial asbestos exposure. The presence of such biomarkers may assist an asbestos personal injury evaluation. A postmortem examination performed on a 72-year-old man with known long-standing yellow nail syndrome identified pleural plaques and diffuse pleural thickening. An evaluation of the occupational history identified no known asbestos exposure. Electron microscopic mineral fibre analysis detected no asbestos fibres. To the best of our knowledge, this is the only case of yellow nail syndrome in which these benign pleural changes are reported ex asbestos. Alternate causes for such pleural pathology were absent. There is merit in physicians and pathologists having an awareness of these new manifestations when considering claimed asbestos related changes during life and at postmortem.

Anthophyllite Asbestos: The Role of Fiber Width in Mesothelioma Induction Part 1: Epidemiological Studies of Finnish Anthophyllite Asbestos

Anthophyllite asbestos only occurs in a few parts of the world in sufficient quantities to be mined. The largest deposits of anthophyllite asbestos occur in Finland where it was mined for more than 75 years and very extensively used and distributed, anciently, for more than six millennia. Anthophyllite is one of the five minerals known collectively as amphibole asbestos. Studies of the effect of these five mineral fibre types when inhaled have shown that fibre width is an important determinant of mesothelioma induction. Only the “thinner” fibres or those with fiber diameter dimensional profiles predominantly less than 0.25 – 0.30 µm, are clearly mesotheliogenic. The “thicker” ones or those whose predominant widths are greater than these diameters do not appear to show an observable attendant risk of mesothelioma. Observations based on studies of at least, two “thick” forms of amphibole asbestos support these hypotheses. The one is Bolivian crocidolite; the other Finnish anthophyllite. The Finnish anthophyllite industry presents an important opportunity to study the robustness of the theory that fibre width is key to mesothelioma genesis as vast numbers of people in all sectors of the Finnish industry and their families have historically incurred massive fiber exposures sufficient to cause a gross excess of asbestosis. Nonetheless, in spite of these long term, high dose exposures clear evidence for a mesothelioma risk due to anthophyllite asbestos is still lacking.