Cytotoxicity of fibrous antigorite from New Caledonia.

Exposure to asbestos and asbestos-like minerals has been related to the development of severe lung diseases, including cancer and malignant mesothelioma (MM). A high incidence of non-occupational MM was observed in New Caledonia (France) in people living in proximity of serpentinite outcrops, containing chrysotile and fibrous antigorite. Antigorite is a magnesium silicate, which shares with chrysotile asbestos the chemical formula.

Nearly free surface silanols are the critical molecular moieties that initiate the toxicity of silica particles.

Inhalation of silica particles can induce inflammatory lung reactions that lead to silicosis and/or lung cancer when the particles are biopersistent. This toxic activity of silica dusts is extremely variable depending on their source and preparation methods. The exact molecular moiety that explains and predicts this variable toxicity of silica remains elusive.

Quantitative Flow Cytometric Evaluation of Oxidative Stress and Mitochondrial Impairment in RAW 264.7 Macrophages after Exposure to Pristine, Acid Functionalized, or Annealed Carbon Nanotubes.

Conventional nanotoxicological assays are subjected to various interferences with nanoparticles and especially carbon nanotubes. A multiparametric flow cytometry (FCM) methodology was developed here as an alternative to quantify oxidative stress, mitochondrial impairment, and later cytotoxic and genotoxic events. The experiments were conducted on RAW264.

The puzzling issue of silica toxicity: are silanols bridging the gaps between surface states and pathogenicity?

Background: Silica continues to represent an intriguing topic of fundamental and applied research across various scientific fields, from geology to physics, chemistry, cell biology, and particle toxicology. The pathogenic activity of silica is variable, depending on the physico-chemical features of the particles. In the last 50 years, crystallinity and capacity to generate free radicals have been recognized as relevant features for silica toxicity.

Assessment of the potential respiratory hazard of volcanic ash from future Icelandic eruptions: a study of archived basaltic to rhyolitic ash samples.

Background: The eruptions of Eyjafjallajökull (2010) and Grímsvötn (2011), Iceland, triggered immediate, international consideration of the respiratory health hazard of inhaling volcanic ash, and prompted the need to estimate the potential hazard posed by future eruptions of Iceland's volcanoes to Icelandic and Northern European populations.

Methods: A physicochemical characterization and toxicological assessment was conducted on a suite of archived ash samples spanning the spectrum of past eruptions (basaltic to rhyolitic magmatic composition) of Icelandic volcanoes following a protocol specifically designed by the International Volcanic Health Hazard Network.

Results: Icelandic ash can be of a respirable size (up to 11.

Ζ potential evidences silanol heterogeneity induced by metal contaminants at the quartz surface: Implications in membrane damage.

Among the physico-chemical features responsible for the so-called "variability of quartz hazard", a key role has been assigned to the silica surface charge, evaluated by means of ζ potential measurement. The ζ potential of silica describes the protonation state of silanols which, in turn, determine interactions with cell membranes. To gain a molecular understanding of the role of silanols in silica pathogenicity, we conducted a systematic investigation of the variation of the ζ potential as a function of pH (ζ plot titration curve) on a large set of respirable quartz particles with different levels of metal contaminants.

Unveiling the Variability of "Quartz Hazard" in Light of Recent Toxicological Findings.

The variability of quartz hazard stands as one of the most puzzling issues in particle toxicology, notwithstanding the fact that silicosis, the most ancient occupational disease, was the very topic from which the study of the toxicity of particulates developed. Over the years, other adverse effects of silica particles (i.e.

Evaluating the mechanistic evidence and key data gaps in assessing the potential carcinogenicity of carbon nanotubes and nanofibers in humans.

In an evaluation of carbon nanotubes (CNTs) for the IARC Monograph 111, the Mechanisms Subgroup was tasked with assessing the strength of evidence on the potential carcinogenicity of CNTs in humans. The mechanistic evidence was considered to be not strong enough to alter the evaluations based on the animal data. In this paper, we provide an extended, in-depth examination of the in vivo and in vitro experimental studies according to current hypotheses on the carcinogenicity of inhaled particles and fibers.

Editor's Highlight: Abrasion of Artificial Stones as a New Cause of an Ancient Disease. Physicochemical Features and Cellular Responses.

New outbursts of silicosis were recently reported among workers manufacturing an engineered material known as "artificial stone," composed by high percentages of quartz (up to 98%) agglomerated with pigments and polymeric resins. Dusts released by abrasion during artificial stone polishing were characterized for particle size, morphology, and elemental composition and studied for (1) ability to catalyze free radical generation in acellular tests, (2) membranolytic potential on human erythrocytes, (3) cytotoxic activity (lactate dehydrogenase release) on murine alveolar macrophages (MH-S) and human bronchial epithelial (BEAS-2B) cell lines, (4) induction of epithelial-mesenchymal transition (EMT) in BEAS-2B cells. Min-U-Sil 5 was used as reference quartz.

Physico-chemical properties of quartz from industrial manufacturing and its cytotoxic effects on alveolar macrophages: The case of green sand mould casting for iron production.

Industrial processing of materials containing quartz induces physico-chemical modifications that contribute to the variability of quartz hazard in different plants. Here, modifications affecting a quartz-rich sand during cast iron production, have been investigated. Composition, morphology, presence of radicals associated to quartz and reactivity in free radical generation were studied on a raw sand and on a dust recovered after mould dismantling.

Free-radical chemistry as a means to evaluate lunar dust health hazard in view of future missions to the moon.

Lunar dust toxicity has to be evaluated in view of future manned missions to the Moon. Previous studies on lunar specimens and simulated dusts have revealed an oxidant activity assigned to HO· release. However, the mechanisms behind the reactivity of lunar dust are still quite unclear at the molecular level.

Nanosized TiO2 is internalized by dorsal root ganglion cells and causes damage via apoptosis.

Unlabelled: Titanium dioxide (TiO2) is widely used as ingredient in several products in the nanoform. TiO2-nanoparticles (NPs) are also currently studied for different medical applications. A large debate exists on possible adverse health effects related to their exposure.

Possible Chemical Source of Discrepancy between in Vitro and in Vivo Tests in Nanotoxicology Caused by Strong Adsorption of Buffer Components.

In the course of studies of the interaction of proteins with TiO2 nanoparticles, we have investigated the role of the medium employed in cellular tests, by measuring the variation of ζ-potential vs pH in the range 2-9 and bovine serum albumin adsorption on TiO2 P25 in the presence of either HEPES or PBS as buffers, both mimicking the physiological pH, but with different chemical nature. The two buffers yield remarkably dissimilar surface charges and protein uptake, i.e.

Why does the hemolytic activity of silica predict its pro-inflammatory activity?

Background: The hemolytic activity of inhaled particles such as silica has been widely investigated in the past and represents a usual toxicological endpoint to characterize particle reactivity despite the fact that red blood cells (RBCs) are not involved in the pathogenesis of pulmonary inflammation or fibrosis caused by some inhaled particles. The inflammatory process induced by silica starts with the activation of the inflammasome, which leads to the release of mature IL-1β. One of the upstream mechanisms causing activation of the inflammasome is the labilization of the phagolysosomal membrane after particle phagocytosis.

Toxicity of boehmite nanoparticles: impact of the ultrafine fraction and of the agglomerates size on cytotoxicity and pro-inflammatory response.

Boehmite (γ-AlOOH) nanoparticles (NPs) are used in a wide range of industrial applications. However, little is known about their potential toxicity. This study aimed at a better understanding of the relationship between the physico-chemical properties of these NPs and their in vitro biological activity.

Imogolite: an aluminosilicate nanotube endowed with low cytotoxicity and genotoxicity.

High-aspect-ratio nanomaterials (HARN) (typically, single-walled carbon nanotubes (SWCNT) or multiwalled carbon nanotubes (MWCNT)) impair airway barrier function and are toxic to macrophages. Here, we assess the biological effects of nanotubes of imogolite (INT), a hydrated alumino-silicate [(OH)3Al2O3SiOH] occurring as single-walled NT, on murine macrophages and human airway epithelial cells. Cell viability was assessed with resazurin.

The influence of surface charge and photo-reactivity on skin-permeation enhancer property of nano-TiO₂ in ex vivo pig skin model under indoor light.

Several topical products contain nanometric TiO2 (nano-TiO2), which is a useful and safe component that absorbs UV light and does not cross skin barrier. However, nano-TiO2 may impregnate the first layer of the skin (stratum corneum, SC) and generate free radicals, even under low UV irradiation. These properties, largely dependent on TiO2 surface chemistry, may modulate the transdermal drug permeation.

In vitro cellular responses to silicon carbide particles manufactured through the Acheson process: impact of physico-chemical features on pro-inflammatory and pro-oxidative effects.

Silicon carbide (SiC) an industrial-scale product manufactured through the Acheson process, is largely employed in various applications. Its toxicity has been poorly investigated. Our study aims at characterizing the physico-chemical features and the in vitro impact on biological activity of five manufactured SiC powders: two coarse powders (SiC C1/C2), two fine powders (SiC F1/F2) and a powder rich in iron impurities (SiC I).

Hydroxyl density affects the interaction of fibrinogen with silica nanoparticles at physiological concentration.

An increasing interest in the interaction between blood serum proteins and nanoparticles has emerged over the last years. In fact, this process plays a key role in the biological response to nanoparticles. The behavior of proteins at the biofluid/material interface is driven by the physico-chemical properties of the surface.

Crystalline phase modulates the potency of nanometric TiO₂ to adhere to and perturb the stratum corneum of porcine skin under indoor light.

Nanometric TiO₂ is largely employed in cosmetics, but in vitro toxic effects have been reported when nano-TiO₂ is exposed to UV light. The photoreactivity of TiO₂ largely depends on its crystal phase, namely, anatase and rutile. Surface acidity, which is also dependent on crystal structure, may impart a positive or negative charge to the nanomaterial surface and ultimately modulate particle adhesion to tissues.

Inhibition of catecholamine secretion by iron-rich and iron-deprived multiwalled carbon nanotubes in chromaffin cells.

The assay of the toxic effects of carbon nanotubes (CNTs) on human health is a stringent need in view of their expected increasing exploitation in industrial and biomedical applications. Most studies so far have been focused on lung toxicity, as the respiratory tract is the main entry of airborne particulate, but there is also recent evidence on the existence of toxic effects of multiwalled carbon nanotubes (MWCNTs) on neuronal and neuroendocrine cells (Belyanskaya et al., 2009; Xu et al.

Pleural mesothelioma: epidemiological and public health issues. Report from the Second Italian Consensus Conference on Pleural Mesothelioma.

Malignant mesothelioma is closely connected to asbestos exposure, with epidemiological patterns closely reshaping the geography and history of asbestos exposure. Mechanisms of causation and of interaction of asbestos fibres with pleura are complex and currently not yet completely understood. Curative efforts so far provided little results.

In search of the chemical basis of the hemolytic potential of silicas.

The membranolytic activity of silica particles toward red blood cells (RBCs) has been known for a long time and is sometimes associated with silica pathogenicity. However, the molecular mechanism and the reasons why hemolysis differs according to the silica form are still obscure. A panel of 15 crystalline (pure and commercial) and amorphous (pyrogenic, precipitated from aqueous solutions, vitreous) silica samples differing in size, origin, morphology, and surface chemical composition were selected and specifically prepared.