Search

Amphibole asbestos is related to multiple diseases, mainly those targeting the lungs. Asbestos-related malignancies can also be caused by non-regulated asbestiform minerals and some elongated mineral particles (EMPs). In particular, the role of nano- and micro-sized EMPs internalized by lung epithelial cells must be clarified. This is of major importance when considering that EMPs to which humans are exposed are likely a highly heterogeneous mix of different mineral types, shapes, and sizes. Here, we document that particles smaller than 4.54 µm in length and smaller than 0.89 µm in width (e.g., particles that do not fit the regulatory categories to be identified as asbestos) are easily internalized because of their specific dimensions, surface charge, and shape (mostly dictated by the aspect ratio L/w). Once internalized, these particles can be found in proximity to the cell nucleus, in vesicles, and in the cytoplasm. Examining the localization of particles in cells provides important information, which helps in determining the physicochemical environment found inside the biological compartment, thus allowing for a better comprehension of the mineralogical transformation that might happen after internalization by cells. [ABSTRACT FROM AUTHOR]

Calcium oxalate phytoliths are one of the most prominent types of Ca speciation in the plant kingdom, and they store extensive amounts of carbon in crystalline form. Ca phytoliths were investigated in the root, trunk, and bark of Vitis vinifera Chasselas from a vineyard in Alsace, France. A multi-analytical approach was used, which included SEM coupled with EDX spectroscopy, XRD, XRF, TGA, and 13C-NMR spectroscopy. These techniques revealed that phytoliths are composed of crystalline calcium oxalate monohydrate (whewellite). The whewellite crystals exhibited mostly equant or short-prismatic habits in all of the three studied grapevine parts, but bipyramidal crystals also occurred. Raphide crystals were only observed in the root, where they were abundant. Instead of using wet chemical procedures to extract the mineral components from the organic parts of the biomass, a thermal treatment via calcination was chosen. The suitable temperature of calcination was determined through TGA experiments. The calcination of the biomass samples at 250 °C enhanced the amounts of Ca phytoliths in the residual chars. The thermal treatment, however, affected the appearance of the Ca oxalate crystals by producing surfaces that displayed macroporosity and by creating fractures. For calcination at both 300 °C and 350 °C, Ca oxalate lost a molecule of carbon monoxide to form Ca carbonate, and the modifications of the original crystal surfaces were more pronounced than those observed after thermal treatment at 250 °C. [ABSTRACT FROM AUTHOR]

Vibrational spectroscopies (Fourier Transform Infra Red, FTIR, and Raman) are exceptionally valuable tools for the identification and crystal-chemical study of fibrous minerals, and asbestos amphiboles in particular. Raman spectroscopy has been widely applied in toxicological studies and thus a large corpus of reference data on regulated species is found in the literature. However, FTIR spectroscopy has been mostly used in crystal-chemical studies and very few data are found on asbestos amphiboles. This paper is intended to fill this gap. We report new FTIR data collected on a suite of well-characterized samples of the five regulated amphibole species: anthophyllite, amosite, and crocidolite, provided by the Union for International Cancer Control (UICC) Organization, and tremolite and actinolite, from two well-known occurrences. The data from these reference samples have been augmented by results from additional specimens to clarify some aspects of their spectroscopic features. We show that the FTIR spectra in both the OH-stretching region and in the lattice modes region can be effective for rapid identification of the asbestos type. [ABSTRACT FROM AUTHOR]

Around the world, charcoal has persisted as an energy resource and retained unequivocal dominance in the energy consumption mix of some nations many years on since modern alternatives were invented. Furthermore, it has secured unyielding significance as a commodity on local and international markets and remained an aggressive competitor to electricity and gas for cooking. Here, we analyze the charcoal supply chain and highlight the rudimentary production techniques common within the sub-Saharan region, using Uganda as an example. Top global producers, importers, and exporters are discussed and, based on fieldwork from ten locations in Uganda, we describe common trade practices, economic contributions and the realities of charcoal consumption in areas with concentrated grid and electricity coverage. Indeed, forest degradation and deforestation in the charcoal trade is indiscriminate and the world's top producers and exporters of charcoal do not necessarily have vast forest resources. Pyrolysis, the process used to produce charcoal from wood, exacerbates risks of wild fires and deteriorates air quality. Our fieldwork indicates that little to no innovation exists to manage waste materials such as ash and polluting gases along the supply chain. Recommendations for the future include better forest conservation practices and more innovation at the cooking level, because effects of localized environmental degradation inevitably lead to negative impacts beyond geographical borders. [ABSTRACT FROM AUTHOR]

One of the open questions regarding the asbestos problem is the fate of the mineral fibres in the body once inhaled and deposited in the deep respiratory system. In this context, the present paper reports the results of an electron microscopy study of both mineral fibres and asbestos bodies found in the lung tissue of a patient who died of malignant mesothelioma due to past occupational exposure. In concert with previous in vivo animal studies, our data provide evidence that amphibole asbestos fibres are durable in the lungs, whereas chrysotile fibres are transformed into a silica-rich product, which can be easily cleared. Amphibole fibres recovered from samples of tissue of the deceased display a high degree of crystallinity but also show a very thin amorphous layer on their surface; 31% of the fibres are coated with asbestos bodies consisting of a mixture of ferroproteins (mainly ferritin). Here, we propose an improved model for the coating process. Formation of a coating on the fibres is a defence mechanism against fibres that are longer than 10 µm and thinner than 0.5 µm, which macrophages cannot engulf. The mature asbestos bodies show signs of degradation, and the iron stored in ferritin may be released and potentially increase oxidative stress in the lung tissue. [ABSTRACT FROM AUTHOR]

In nature, asbestos is often associated with minerals and other non-asbestiform morphologies thought to be harmless, but not much is known about the potential toxic effects of these phases. Therefore, the characterization of natural assemblages should not be limited to asbestos fibers only. This paper combines a multi-analytical characterization of asbestos from Valmalenco (Italy) with data from dissolution experiments conducted in a simulated interstitial lung fluid (Gamble's solution), and a detailed dimensional study that compares the particle population before and after this interaction. The sample is identified as a tremolitic amphibole, exhibiting a predominance of fiber and prismatic habits at lower magnification, but a bladed habit at higher magnification. The results show that at different magnification, the dimensional and habit distributions are notably different. After the dissolution experiments, the sample showed rounded edges and pyramid-shaped dissolution pits. Chemical analyses suggested that a nearly stoichiometric logarithmic loss of Si and Mg occurred associated with a relatively intense release of Ca in the first 24 h, whereas Fe was probably redeposited on the fiber surfaces. A rearrangement of the more frequent habits and dimensions was recorded after the dissolution experiment, with a peculiar increase of the proportion of elongated mineral particles. [ABSTRACT FROM AUTHOR]