Chrysotile, crocidolite, asbestiform erionite: mineralogical characterization and cytotoxic effects

UICC chrysotile, chrysotile from Val Malenco, erionite from Nevada and UICC crocidolite fibers were characterized through Transmission Electron Microscopy (TEM) with annexed Energy Dispersive Spectroscopy (EDS). The TEM study was performed forward on three levels for each single sample. The first observed aspect was the morphological and dimensional study: typical fibrous morphology was observed for all the analyzed samples. For each sample 100 fibers were investigated: were registered their dimension (length and diameter) and the L/d ratio were calculated in order to understand if the fibers population can entry in particular dimensional categories (e.g. WHO criteria, Stanton’s Hypothesis criteria or EPA dimensional limits). The second observed aspect was the chemical composition of the fibers. Also the chemistry match well with the expected for this minerals. In particular, both the chrysotile samples show the presence of aluminum and iron as substitute of tetrahedral and octahedral typical cations; the crocidolite bears an adding of calcium and the erionite has magnesium and iron cations normally unexpected in the general formula. At the latter investigation level, all the fibers showed a high degree of crystallinity in the diffraction patterns study, without evidence of natural amorphization (e.g. weathering). These characterized mineral fibres were administrated for 6, 12, 24 and 48h in human bronchial and mesothelial cells, at the concentration of 50µg/ml, to evaluate their cytotoxic effects; some biofunctional parameters at time points were evaluated: % number of alive, death and apoptotic cells; % number of cells with low, medium, high ROS content. These data confirm higher cytotoxic effects exerted by UICC crocidolite and UICC chrysotile, particularly evident since short times of contact (6, 12h). Our next purpose will be to characterize the same fibers extracted from cells after culture treatments

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 asbestoslike 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

Expected performance of the ASTRI-SST-2M telescope prototype

ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) is an Italian flagship project pursued by INAF (Istituto Nazionale di Astrofisica) strictly linked to the development of the Cherenkov Telescope Array, CTA. Primary goal of the ASTRI program is the design and production of an end-to-end prototype of a Small Size Telescope for the CTA sub-array devoted to the highest gamma-ray energy region. The prototype, named ASTRI SST-2M, will be tested on field in Italy during 2014. This telescope will be the first Cherenkov telescope adopting the double reflection layout in a Schwarzschild-Couder configuration with a tessellated primary mirror and a monolithic secondary mirror. The collected light will be focused on a compact and light-weight camera based on silicon photo-multipliers covering a 9.6 deg full field of view. Detailed Monte Carlo simulations have been performed to estimate the performance of the planned telescope. The results regarding its energy threshold, sensitivity and angular resolution are shown and discussed.Comment: In Proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at arXiv:1307.223

Applying Definitions of “Asbestos” to Environmental and “Low-Dose” Exposure Levels and Health Effects, Particularly Malignant Mesothelioma

Although asbestos research has been ongoing for decades, this increased knowledge has not led to consensus in many areas of the field. Two such areas of controversy include the specific definitions of asbestos, and limitations in understanding exposure-response relationships for various asbestos types and exposure levels and disease. This document reviews the current regulatory and mineralogical definitions and how variability in these definitions has led to difficulties in the discussion and comparison of both experimental laboratory and human epidemiological studies for asbestos. This review also examines the issues of exposure measurement in both animal and human studies, and discusses the impact of these issues on determination of cause for asbestos-related diseases. Limitations include the lack of detailed characterization and limited quantification of the fibers in most studies. Associated data gaps and research needs are also enumerated in this review