Search

Mesothelioma is a fatal disease that has historically been associated with exposure to airborne asbestos. Because occupational asbestos exposures dropped dramatically in the late 1960s and early 1970s, far fewer cases of mesothelioma today are due to these fibers but, instead, are usually a result of the aging process or genetic predisposition. In May of 2022, a Morbidity and Mortality Weekly Report (MMWR) was issued by the Centers for Disease Control and Prevention (CDC) regarding malignant mesothelioma incidence in women from 1999 to 2020. While this MMWR alerted citizens to the continued presence of the disease, after reading this article one might have thought that the CDC was suggesting that the disease was increasing in women due to asbestos exposures (which it is not). In the present analysis, we investigate several factors related to the interpretation of epidemiological data for mesothelioma, including the role of asbestos as a risk factor over time. The authors conducted a review of the scientific community's understanding of mesothelioma incidence and asbestos exposures amongst women, as well as an investigation of the methods and references in the MMWR article. Although various articles have recently discussed the incidence of both peritoneal and pleural mesothelioma in women, it is fortunate that the age-adjusted rates for mesothelioma have remained flat (neither increased nor decreased significantly) in women for the past 50 years. Incredibly few women in the U. S. have had appreciable cumulative exposures to any type of asbestos (chrysotile, amosite, or crocidolite) in the workplace or from the ambient environment, especially since about 1965–1970. In this paper, we highlight six factors that should be considered when evaluating the incidence of mesothelioma amongst American women in the current era. Without sufficient consideration of these factors, improper conclusions have been drawn over the past several years. [ABSTRACT FROM AUTHOR]

Waste generated during asbestos manufacturing contains substantial quantities of iron, nickel, magnesium, and silicon. The existing techniques for processing chrysotile-asbestos waste (CAW) cannot fully recover these elements. Therefore this paper presents a hydrometallurgical method for processing the CAW of the Zhitikara deposit in the Kostanay region of Kazakhstan. Batch reactors are used in both laboratory and pilot experiments, and initial trials are conducted in a recently constructed industrial Ti reactor at the Kostanay Minerals JSC plant in the Kostanay region of Zhitikara. The primary benefits of the industrial reactor include operation without excessively grinding the feedstock and creation of a pulp with enhanced filtration properties. A moderate agitation speed (10 rpm) helps ensure a consistent pulp density and prevent the production of silica gel. Optimal leaching conditions are determined as a fraction size of CAW between − 1.25 and 0.25 mm, hydrochloric acid concentration of 18 wt%, temperature of ~ 85–90 °C, pressure of 1 atmosphere, and duration of 2 h. An investigation of the process kinetics reveals that diffusion is the rate-controlling step. Further, the activation energies are determined to be 54.4 kJ.mol− 1, and the leaching rates of Mg, Fe, and Ni under these conditions are 96.0, 87.8, and 81.3%, respectively. Washing and recycling water enhances helps to increase the recovery of magnesium chloride. Implementing pilot-scale hydrometallurgical processing of CAW can effectively address environmental issues that pose a threat to human health and provide commercial advantages. [ABSTRACT FROM AUTHOR]

Serpentine (Mg3Si2O5(OH)4), like quartz, dolomite and magnesite minerals, is a versatile mineral group characterized by silica and magnesium silicate contents with multiple polymorphic phases. Among the phases composed of antigorite, lizardite, and chrysotile, lizardite and chrysotile are the most prevalent phases in the serpentinites studied here. The formation process of serpentinites, which arise from the hydrothermal alteration of peridotites, influences the ratio of light rare earth elements (LREE) to heavy rare earth elements (HREE). In serpentinites, the ratio of light rare earth elements (LREE)/heavy rare earth elements (HREE) provides insights into formation conditions, geochemical evolution, and magmatic processes. The depletion of REE compositions in serpentinites indicates high melting extraction for fore-arc/mantle wedge serpentinites. The studied serpentinites show a depletion in REE concentrations compared to chondrite values, with HREE exhibiting a lesser degree of depletion compared to LREE. The high ΣLREE/ΣHREE ratios of the samples are between 0.16 and 4 ppm. While Ce shows a strong negative anomaly (0.1–12), Eu shows a weak positive anomaly (0.1–0.3). This indicates that fluid interacts significantly with rock during serpentinization, and highly incompatible elements (HIEs) gradually become involved in the serpentinization process. While high REE concentrations indicate mantle wedge serpentinites, REE levels are lower in mid-ocean ridge serpentinites. The enrichment of LREE in the analyzed samples reflects melt/rock interaction with depleted mantle and is consistent with rock–water interaction during serpentinization. The gradual increase in highly incompatible elements (HIEs) suggests that they result from fluid integration into the system and a subduction process. The large differential thermal analysis (DTA) peak at 810–830 °C is an important sign of dehydration, transformation reactions and thermal decomposition, and is compatible with H2O phyllosilicates in the mineral structure losing water at this temperature. In SEM images, chrysotile, which has a fibrous structure, and lizardite, which has a flat appearance, transform into talc as a result of dehydration with increasing temperature. Therefore, the sudden temperature drop observed in DTA graphs is an indicator of crystal form transformation and CO2 loss. In this study, the mineralogical and structural properties and the formation of serpentinites were examined for the first time using thermo-gravimetric analysis methods. In addition, the mineralogical and physical properties of serpentinites can be recommended for industrial use as additives in polymers or in the adsorption of organic pollutants. As a result, the high refractory nature of examined serpentine suggests that it is well-suited for applications involving high temperatures. This includes industries such as metallurgy and steel production, glass manufacturing, ceramic production, and the chemical industry. [ABSTRACT FROM AUTHOR]

This study aimed to estimate workers' occupational lifetime exposure to chrysotile and examine the respiratory symptoms and lung cancer risk. A total of 112 workers were interviewed about their occupational histories. Exposure modeling using information on the determinants of exposure was used to estimate chrysotile emissions. The cumulative lifetime exposure was then assessed for each worker. Respiratory symptoms were obtained using a validated questionnaire. Lung cancer mortality rate was also predicted using a model. Almost all the workers were male and young (mean age = 30 years, SD = 7). The estimated lifetime occupational chrysotile inhalation exposure ranged from 0.0001 to 0.0486 f/mL.years (median = 0.0018 f/mL.years, IQR = 0.486). A high prevalence of cough symptom (11.7%), and low estimated cancer risk (<1%) were reported. In conclusion, the lung cancer risk among our cohort of workers was at a low level because of lower cumulative lifetime occupational chrysotile exposure. [ABSTRACT FROM AUTHOR]

The discovery of the detrimental effects of asbestos on human health came long after its widespread use, with the first scientific evidence of asbestos-related diseases emerging in the late 19th and early 20th centuries. Despite efforts to ban its use, asbestos continues to be mined and used in Central Asia (as well as in Russia, China, and other countries). To gain a deeper understanding of the situation in Central Asia, we have conducted a review of scientific literature on the use of asbestos, exposure assessment, and health consequences of asbestos exposure in this geographic area. This review encompasses studies about exposure assessments, epidemiological data, and biochemical or clinical surveys conducted in Kazakhstan, Uzbekistan, Tajikistan, Turkmenistan, and Kyrgyzstan. A total of 18 articles met the inclusion criteria, and their content is summarised in this review, which represents the first attempt to systematically examine research on asbestos and its impact on the health of workers and the general population in Central Asia countries, including literature published in Russian and English. The findings here highlighted the substantial limitations of the currently available knowledge about the impact of asbestos on health in this geographical area. [ABSTRACT FROM AUTHOR]

The aim of this paper is to examine the environmental resistance and chrysotile content of different asbestos cement products and to prove the relationship between these two factors by analytical results. The paper includes Fourier-transform infrared (FT-IR) spectroscopic analysis of asbestos cement pipes and asbestos cement products with corrugated and flat characteristics. The methodology of the study is based on FT-IR spectroscopy and general statistical approaches, and the results obtained are compared using correlation analysis. The background to the topic is that asbestos cement products are still widely used today despite their harmful effects on health, contrary to European Union asbestos-free targets. A damaged and eroded asbestos cement product loses several grams of asbestos and cement per year from its matrix structure, which is exacerbated by exposure to various environmental influences. The match rate of the chrysotile spectrum for analysed samples has been over 50 % in each case. In the number of measurements, the chrysotile detection rate was 7.64 % higher for degraded and eroded samples. In addition, in the samples exposed to environmental factors, the percentage variance was approximately 10 % or higher, with the exception of asbestos cement pipes. The results provide a basis for situational awareness options. Analytic practitioners, material science researchers, and analysts can use them. [ABSTRACT FROM AUTHOR]

The rapid expansion of textile industries has contributed significantly to non‐biodegradable waste generation, presenting a global environmental challenge. Additionally, waste from the mining industry, such as chrysotile serpentine, contributes to this environmental issue. Therefore, this study investigates the possibility of recycling polyamide 6 waste combined with chrysotile serpentine waste to produce nanotextile fabric‐based composite (NTF‐BC). This study highlights the environmental significance of sustainable techniques in waste management specifically within the textile industry. The chrysotile serpentine waste was intensively pulverized into nanoscale particles to eliminate its hazardous fibrous nature and facilitate the electrospinning process. Comprehensive characterization was conducted using various analytical techniques including XRD, XRF, FT‐IR, SEM, BET, and DMA, to explore the properties of prepared fabrics as a function of electrospinning parameters (Ctl.Sp concentration, spinning distance, applied voltage, and flow rate.). SEM analysis indicated optimal fabrication conditions for smoother and more homogeneous NTF‐BC at Ctl.Sp concentration of 7.5%, voltage of 20 kV, spinning distance of 15 cm, and flow rate of 1 mL/h. XRD and FT‐IR analyses showed that increasing the Ctl.Sp ratio, distance, and voltage negatively affected sample crystallinity and favored the α‐form over the γ‐form. In terms of DMA characteristics, the Ctl.Sp ratio and applied voltage positively impacted the E′ values, with minimal influence from spinning distance and rate. Notably, the highest geometric properties (i.e., SBET and Vt) of the fabricated NTF‐BC were attained at the lowest Ctl.Sp ratio of 5%. [ABSTRACT FROM AUTHOR]

BackgroundChrysotile is widely used in construction and industry. Research has shown that it is associated with lung fibrosis in occupational groups, but the involvement of microRNAs (miRNAs) in chrysotile-induced lung fibrosis has been less well studied, and the specific mechanism is still unclear. ObjectiveUsing next-generation sequencing technology to analyze the effects of chrysotile exposure on the miRNAs expression profiles of human lung epithelial cells (BEAS-2B cells), to explore the variations of differentially expressed miRNAs and related signaling pathways, and to identify potential targets and molecular mechanisms of chrysotile-induced lung fibrosis. MethodsChrysotile was analyzed with a laser particle size analyzer and an X-ray diffractometer for particle size and physical phase. BEAS-2B cells were exposed to chrysotile for designed time sessions (12, 24, and 48 h) and doses (0, 50, 100, and 200 μg·mL−1). Cell viability was detected with a cell viability assay kit (CCK8); expression levels of Fibronectin, Collagen-Ⅰ, and α-smooth muscle actin (α-SMA) were detected by Western blot after exposure to 200 μg·mL−1 chrysotile for 24 h. Sample correlation and changes in miRNAs expression profiles between the chrysotile-exposed and the control groups were analyzed by next-generation sequencing technology. The target genes of differentially expressed miRNAs were predicted and subjected to Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. ResultsThe average particle size of the chrysotile dust sample used in this study was 3.58 μm, and the results of X-ray diffraction analysis confirmed the characteristic peaks of chrysotile. Compared with the control group, the chrysotile gradually inhibited the survival rate of BEAS-2B cells with increasing concentration and exposure time (P

Abstract Serpentine minerals, either polymorphs or polytypes (mostly chrysotile, lizardite and antigorite), are hardly distinguished in ophiolitic serpentinites and serpentinized peridotite unless sophisticated mineralogical tools are applied. Among them, chrysotile has special chemical and structural characteristics, which can be used to identify and classify different modes, and accordingly as significant petrographic indicators of serpentinization in ophiolite sequences. Generally, chrysotile characterizes low-grade metamorphism and it occurs in massive serpentinites as well as asbestos veinlets traversing them. The present paper aims to characterize the different modes of chrysotile in serpenitinite and serpentinized peridotite from the Semail ophiolite at the Daftah area in the United Arab Emirates (UAE). The objectives include microscopic and chemical separation of three chrysotile modes; namely slip-fiber (most common), mass fiber (common) and cross-fiber (less common). The cross-fiber mode is considered a “spinning type” in sheared serpentinite with asbestos veinlets whereas the other two belong to “non-spinning type” in massive serpentinite being formed by a contact volume metasomatic process by replacement of olivine and pyroxene. Excess Mg from the transformation of ferromagnesian minerals into chrysotile, in the presence of additional SiO2, results in an association of cryptocrystalline talc with the chrysotile fibers. Differential thermal analysis (DTA) and thermogravimetry (TG) indicate that the process of thermal decomposition of chrysotile leads to the formation of olivine (forsterite). The infra-red (IR) absorption technique for end products of some selected samples appear to indicate that the spectra of the end products are similar and the absorption bands are assigned in the range of (1100–800 cm−1) and (700–200 cm−1) corresponding to Si–O and Mg–O vibration modes. Based on the findings of the present paper, the chrysotile serpentinization process is due to metasomatic replacement of peridotite during the ocean floor early episode and later an episode of ophiolite obduction. The chemical data focalize that the similarity in chemical behaviour of chrysotile veins implies that a close cogenetic relationship among three modes of chrysotile and removal of such major elements occurred during serpentinization; Mg, Fe and Si were removal in solution from the peridotite and precipitated in tension and shear fractures to form fibrous chrysotile and magnetite. Also, it can be concluded that the mode of occurrence and timing of chrysotile vein formation can be fitted according to the type of chrysotile mode. Cross-fiber type develops along tension fractures whereas mass-fiber type is finally developed via CO2 metasomatism. Finally, the slip-fiber type forms by a volume-for volume metasomatic process due to the replacement of olivine and/or pyroxene. In terms of time and tectonism, the different mode witnessed different metamorphic/metasomatic events and structures. Shear deformation is more likely connected to the formation of cross-fibers in NW- and NE-trending asbestos veins and veinlets.

The Gysian ophiolite of NW Iran is located at the intersection of the ophiolite belts of SE Turkey, NE Iraq, and Iran, and provides the opportunity to investigate the preserved subduction and obduction history of an important tectonic site that has not previously been studied. The serpentinized peridotites of the Gysian ophiolite contain the assemblage lizardite + chrysotile + spinel/Mg-spinel with relict clinopyroxene (diopside) and very rare relict orthopyroxene and olivine. The compositions of clinopyroxenes and spinels are more consistent with the formation of the inferred protolith harzburgites in a fore-arc or supra-subduction zone instead of an abyssal environment. The Gysian ophiolite is a remnant of the Neo-Tethyan arc-ophiolitic system and records shallow subduction (< 50 km, indicated by the absence of antigorite) in the Late Cretaceous to Paleocene before obduction along thrust faults over the continental margin. We review the spatial trends of the metamorphic grade of the Neo-Tethyan ophiolites in this region and provide detailed information about the petrology and mineral chemistry of the Gysian ophiolite. [ABSTRACT FROM AUTHOR]

Most asbestos-related studies have focused on asbestos exposure risks, their associated health implications, and waste management issues. Our research introduced a unique perspective that has rarely been explored: the impact of environmental factors on asbestos cement products. The novelty of the study is that, in contrast to previous research, in addition to determining the material quality of asbestos, it analyses the trace materials, additives and the emissive nature of chrysotile fibers. This study aims to identify the chrysotile-asbestos content in three common asbestos cement products found in Hungary, with regard to the release of their fibers upon exposure to the environment and to identify trace elements that could be used to identify the origin and function of each of these products. Our analyses revealed the presence of chrysotile in each tested sample, with spectral matches ranging from 59.6% to 86.7%. Asbestos cement products exposed to various environmental influences for long periods showed a greater chrysotile emission capacity than those unexposed or hermetically sealed ones. Additionally, we established that all asbestos cement products contained glass fibers, with an average spectral match of 62.1%. We further identified polysilicate in the materials with an average spectral match of 66.0%, as it was included in asbestos cement products to enhance their heat resistance. Our results pave the way for a new methodology for assessing asbestos cement products with regard to the implementation of their trace element level assessments. [ABSTRACT FROM AUTHOR]

Studies of magnesium (Mg) isotope ratios in subduction zone lavas have revealed small but significant offsets from the mantle value with enrichments in the heavy isotopes. However, the very high concentration of Mg in the mantle contrasts with much lower concentrations in the subducted igneous crust and oceanic sediments, making these subduction components unlikely vehicles of the Mg isotope anomalies in arc lavas. Only serpentinites, which in various proportions form part of oceanic plates, have high Mg contents comparable to fresh mantle rocks, and they have thus been regarded as a potential source of exotic Mg in the source of arc magmas. In this study we analyzed serpentinite samples from different oceanic settings for their Mg isotopic compositions. The majority of samples are indistinguishable from the depleted mantle (δ26Mg=-0.24 ‰ ± 0.04 ‰) irrespective of their origin. Only a small number of seafloor-weathered serpentinites are slightly enriched in the heavy isotopes (up to δ26Mg=-0.14 ‰ ± 0.03 ‰), implying that bulk serpentinites are unlikely sources of isotopically anomalous Mg in subduction zones. We also developed a partial dissolution method in which 5 % acetic acid for 180 min was shown to fully dissolve the minerals brucite and iowaite while leaving the serpentine mineral chrysotile essentially undissolved. Partial dissolution of 11 bulk serpentinite samples revealed Mg isotopic composition of brucite (± iowaite) that is systematically ∼0.25 ‰ heavier than that of coexisting serpentine. Thus, preferential breakdown of brucite and/or iowaite in a subducted slab prior to serpentine could preferentially release isotopically heavy Mg, which could subsequently be transported into the source region of arc magmas. Such a scenario would require brucite/iowaite breakdown to occur at pressures in excess of 3 GPa and produce fluids with very high concentrations of Mg that could be transported to arc magma source regions. Whether these conditions are met in nature has yet to be experimentally investigated. [ABSTRACT FROM AUTHOR]

In this work, the self-made chrysotile fiber membrane (CFM) and raw chrysotile fiber (CF) were calcined in air from 500 to 800 °C. The XRD pattern of CFM showed that the diffraction peak of chrysotile weakened when the temperature was from room temperature to 550 °C, and CFM had a shorter amorphous interval at 600–700 °C. While, no amorphous phase appeared in CF during calcination, and forsterite begined to appear at 650 °C. SEM images showed that CFM could still maintain the integrity of the network structure at 600–800 °C, while CF gradually melted into coarse fiber bundles with the increase of calcination temperature, and sintering traces appeared. After that,the kinetics of the dehydroxylation of chrysotile in CFM and CF was studied. The dehydroxylation of CFM is a one-step reaction, the calculated activation energy is 243.33 kJ mol−1, which conforms to the two-dimensional ‘Valensi’ model with mechanism function G(α) = (1−α)ln(1−α) + α. The dehydroxylation of CF is divided into two stages, the activation energy are 222.87 kJ mol−1 and 316.04 kJ mol−1. The first stage of CF conforms to two-dimensional ‘Jander’ model (n = 2) with mechanism function G(α) = [1−(1−α)1/2]2, the second stage of CF conforms to the random nucleation and subsequent growth ‘Avrami-Erofeev’ model (n = 3/2) with mechanism function G(α) = [−ln(1−α)]2/3. [ABSTRACT FROM AUTHOR]

The paper presents the results of an investigation into the kinetics of catalytic hydrogenation of vacuum residue at temperatures of 380, 400 and 420 °C and different durations, ranging from 30 to 70 min, using a nanocatalyst containing the active metals nickel and titanium supported on chrysotile. It was found that the yield of oils from 30 to 50 wt.% and tars from 12 to 18 wt.% increased with increasing temperatures and reaction times. A slight increase in the proportion of solids in the range of 2.0 to 6.0 wt.% is explained by the activity of the nanocatalyst used. In the study of the kinetics of vacuum residue hydrogenation, using the nanocatalyst developed by the authors, we were able to achieve a low yield of solids with a short contact time as well as a high yield of low-molecular-weight compounds such as oils and tars. To determine the kinetic parameters (rate constants and activation energies), Simpson's integral method and a random search engine optimization method were used. High values of rate constants are characteristic of reactions in the formation of oils k1, tars k2 and asphaltenes k3 in the temperature range of 380–420 °C. The high values of the rate constants k1, k2 and k3 in the catalytic hydrogenation of the vacuum residue indicate the high reaction rate and activity of the nanocatalyst used. With an increase in temperature from 380 to 420 °C, the rate constant of the formation of gas products from vacuum residue and the conversion of asphaltenes into oils significantly increase, which indicates the accumulation of low-molecular-weight compounds in oils. The activation energy for reactions leading to the formation of oils, tars, asphaltenes, gas and solid products was 75.7, 124.8, 40.7, 205.4 and 57.2 kJ/mol, respectively. These data indicate that the processes of vacuum residue hydrogenation with the formation of oils and asphaltenes require the lowest energy inputs. Reducing the process temperature to increase the selectivity of the vacuum residue hydrogenation process when using the prepared nanocatalyst is recommended. The formation of oils at the initial stage plays a key role in the technology of the heavy hydrocarbon feedstock (HHF) hydrogenation process. Perhaps the resulting oils can serve as an additional solvent for high-molecular-weight products such as asphaltenes, as evidenced by the low activation energy of the process. [ABSTRACT FROM AUTHOR]

In this work, the effect of microwave-assisted acid treatments on the morphological and crystallochemical characteristics of chrysotile fibers is investigated. A low concentration of nitric acid (0.2 N) is used to remove Mg2+-species located in the octahedral sheet of its structure, thereby causing a crystallo-chemical change forming a skeleton of non-crystalline amorphous silica. This skeleton maintains an elongated morphology but characterized by rounded -not sharp-edges and porous surfaces whose physical resistance under stress is reduced when compared with the initial fibers of chrysotile, favoring a lower pathogenicity of the fibers. Thus, microwave-assisted acid treatment rise as a low-cost, fast and effective option in avoiding the dangerousness associated with asbestos waste management. [ABSTRACT FROM AUTHOR]

Some layered phyllosilicates are characterized by spontaneous scrolling due to size mismatch between sublayers. The doping of layers by transition metal ions allows nanoscrolls to acquire magnetic properties. The magnetic behavior of synthetic (Mg1 –xCox)3Si2O5(OH)4 (x = 0.2, 0.4, 0.6, 0.8, 1) phyllosilicates with the chrysotile structure before and after partial hydrogen-induced reduction is studied. The dominant ferromagnetic behavior has been revealed in all studied phyllosilicates. Ensembles of cobalt metal nanoparticles in a silicate matrix have demonstrated a collective magnetic response at room temperature with a narrow hysteresis loop and fast saturation. [ABSTRACT FROM AUTHOR]

Thermoacid behavior of serpentinite from the Zhitikarinsky field (g. Zhitikara, Kazakhstan). The character of dissolution of heat-treated serpentinite in a narrow temperature range of 600–750 °C is investigated, where the crystal lattice of the structural structure of chrysotile in sulfuric acid is destroyed. The X-ray and chemical analysis of the products of dissolution of heat-treated serpentinite at 600 °C, 725 °C and 750 °C in sulfuric acid solution show that the reason for the increase in the reactivity of heat-treated serpentinite at 725 °C and 750 °C with respect to the acidic medium and the degree of magnesium extraction into sulfate solution is the formation of periclase (MgO) in the serpentinite composition after heat treatment of them within a temperature range of 600–750 °C. The results were discussed using data obtained by conducting a thermodynamic evaluation of probable reactions during the thermoacid treatment of serpentinite, phase compressions of heat-treated serpentinite at 600–750 °C, and after its acid treatment at 1.0 M H2SO4. [ABSTRACT FROM AUTHOR]

This paper summarizes historical asbestos exposure data collected during the handling of short-fiber chrysotile asbestos that was used as an additive to drilling fluid in oil and gas exploration. A total of 1171 industrial hygiene (IH) personal and area air samples were collected and analyzed from more than 20 drilling rigs between 1972 and 1985. The dataset consists of 1097 short-term samples (<240 min) with more than 80% having sample durations less than 30 min. Average airborne fiber concentrations measured during asbestos handling activities ranged from 0.62 f/cc to 3.39 f/cc using phase-contrast microscopy (PCM). An additional 14 samples were considered long-term samples (>240 min) and there were 60 samples with no reported sample duration. Eight-hour time-weighted average (8-h TWA) results, calculated using short-term samples, along with long-term samples greater than 240 min, did not exceed contemporaneous Occupational Safety and Health Administration (OSHA) permissible exposure limits (PELs). This analysis fills a data gap in the evaluation of asbestos exposures from the use of drilling mud additives (DMAs) that contained chrysotile asbestos. [ABSTRACT FROM AUTHOR]

To evaluate potential airborne asbestos exposures during brake maintenance and repair activities on a P&H overhead crane, and during subsequent handling of the mechanic's clothing. Personal (n = 27) and area (n = 61) airborne fiber concentrations were measured during brake tests, removal, hand sanding, compressed air use, removal and reattachment of chrysotile-containing brake linings, and reinstallation of the brake linings. The mechanic's clothing was used to measure potential exposure during clothes handling. All brake linings contained between 19.9% to 52.4% chrysotile asbestos. No amphibole fibers were detected in any bulk or airborne samples. The average full-shift airborne chrysotile concentration was 0.035 f/cc (PCM-equivalent asbestos-specific fibers, or PCME). Average task-based personal air samples collected during brake maintenance, sanding, compressed air use, and brake lining removal tasks ranged from 0 to 0.48 f/cc (PCME). The calculated 30-minute time-weighted average (TWA) airborne chrysotile concentration associated with 5-15 minutes of clothes handling was 0–0.035 f/cc PCME. The results indicated that personal and area TWA fiber concentrations measured during all crane brake maintenance and clothes handling tasks were below the current OSHA 8-h TWA Permissible Exposure Limit for asbestos of 0.1 f/cc. Further, no airborne asbestos fibers were measured during routine brake maintenance tasks following the manufacturer's maintenance manual procedures. All short-term airborne chrysotile concentrations measured during non-routine tasks were below the current 30-minute OSHA excursion limit for asbestos of 1 f/cc. This study adds to the available data regarding chrysotile exposure potential during maintenance on overhead cranes. [ABSTRACT FROM AUTHOR]

Serpentinization has been widely documented and investigated at mid-ocean ridges (MOR) and subduction zones. In contrast, at magma-poor rifted margins serpentinization has received much less attention, despite its importance in controlling rheology and mass fluxes during breakup and establishing of a steady-state MOR. In this study, we present new petrological and geochemical data on subcontinental exhumed serpentinized peridotites from the spectacularly exposed Platta, Tasna and Totalp nappes in the Eastern Central Alps in SE Switzerland, belonging to the Alpine Tethys Ocean Continent Transition (OCT). The results testify of a complex history of fluid–rock interactions recorded by several serpentinization events starting with lizardite mesh and bastite textures (S1), subsequently followed by a succession of serpentine-filling veins with distinct textures and serpentine polysomes that include spherical polyhedral serpentine (S2); chrysotile ± polygonal ± lizardite banded veins (S3); lamellar antigorite veins and patches (S4) and chrysotile crack-seal (S5). The serpentinization sequence differs at proximal (i.e. continentwards) and distal (i.e. oceanwards) domains of the OCT. At proximal domains of the OCT (Upper Platta, Tasna) serpentinites record the complete serpentinization sequence (S1 to S5), whereas at distal domains (Lower Platta) serpentinization is restricted to pseudomorphic mesh and bastite (S1) and chrysotile crack-seal (S5). We attribute this discrepancy to contrasted mechanisms of mantle exhumation along the OCT. While at proximal domains mantle is unroofed along continuous and single large offset detachment faults allowing for the formation of all serpentine generations, mantle exhumation at distal domains is a more discontinuous process, controlled by sequential out-of-sequence detachment and flip-flop faults preventing the full development of all serpentine generations. In this frame, the nature and order of formation of the serpentine polysomes are directly controlled by the conditions of serpentinization (i.e. temperature, mantle composition and fluid/rock ratio). We propose that this new conceptual model can be extrapolated to serpentinization at slow to ultra-slow MORs, where close similarities in the serpentinization sequences have been recently reported. [ABSTRACT FROM AUTHOR]

Background We investigated mortality in workers of the world's largest chrysotile mine and enrichment factories located in the town of Asbest, Russian Federation. Methods This historical cohort study included all workers employed for at least 1 year between 1975 and 2010 and follow-up until the end of 2015. Cumulative exposure to dust was estimated based on workers' complete occupational history linked to dust measurements systematically collected from the 1950s. Exposure to chrysotile fibers was estimated using dust-to-fiber conversion factors. Relative risks (RRs) and 95% confidence intervals (CIs) were estimated as mortality rate ratios in Poisson regression models. Results A total of 30 445 (32% women) workers accumulated 721 312 person-years at risk and 11 110 (36%) died. Of the workers, 54% had more than 30 years since their first exposure. We found an exposure-response between cumulative dust and lung cancer mortality in men. No clear association with dust exposure but a modest increase in the highest category of fiber exposure was seen for lung cancer in women. Mesothelioma mortality was increased (RR = 7.64, 95% CI = 1.18 to 49.5, to at least 80 fibers per cm3 years and RR = 4.56, 95% CI = 0.94 to 22.1, to at least 150 mg/m3 years [dust]), based on 13 deaths. For colorectal and stomach cancer, there were inconsistent associations. No associations were seen for laryngeal or ovarian cancer. Conclusion In this large-scale epidemiological study in the world's largest active asbestos mine, we confirmed an increased risk of mesothelioma with high fiber exposure and an increasing mortality for lung cancer in men with increasing dust exposure. Less clear-cut increased lung cancer mortality was seen in the women. Continued mortality follow-up is warranted. [ABSTRACT FROM AUTHOR]

The process of transformation of the silicate components of the crystal lattice structure of chrysotile during its quantitative interaction with aqueous solutions containing various stoichiometrically required amounts of sulfuric acid (SRA H2SO4) calculated with respect to the magnesium content in the composition of chrysotile is investigated. It has been shown by IR spectroscopic, X-ray phase, thermal and chemical methods of investigation and analysis that, with quantitative interactions of chrysotile and sulfuric acid, first of all, the "brucite layer" of the molecular structural structure of chrysotile is exposed to acid at SRA H2SO4 = 0.1–0.3. As a result of ion exchange processes, acidic silanol (≡Si–O–H) or disilanol (=Si=(O–H)2) bonds are formed. These acid groups form one-dimensional silicate chains with transverse bridges (≡Si–O–Si≡), where the angles (Si–O–Si = 180 °C) straighten, which are recorded in the IR spectra in the region of characteristic absorption of 1220–1250 cm−1 silica. The association of the resulting acid groups into silicate chains, dimers, and trimers with transverse bridges, leads to the appearance of colloidal silica particles in the system, which cause some inhibition of the dissolution of layered magnesium hydrosilicate in sulfuric acid solutions containing H2SO4 ˃ 0.3 SRA. [ABSTRACT FROM AUTHOR]

The study’s objective was to determine the air quality in an asbestos-related industry and its impact on current workers’ respiratory health. Seventy-seven air and 65 dust samples were collected at 5-day intervals in an asbestos roofing sheets production factory in Sri Lanka having two production facilities. Sampling was performed in ten sites: Defective sheets-storage, Production-plant, Pulverizer, Cement-silo, and Loading-area. A detailed questionnaire and medical screening were conducted on 264 workers, including Lung Function Tests (LFT) and chest X-rays. Asbestos fibres were observed in deposited dust samples collected from seven sites. Free chrysotile fibres were absent in the breathing air samples. Scanning Electron Microscopy confirmed the presence of asbestos fibres, and the Energy Dispersive X-ray analysis revealed Mg, O, and Si in depositions. The average concentrations of trace metals were Cd-2.74, Pb-17.18, Ni-46.68, Cr-81.01, As-7.12, Co-6.77, and Cu-43.04 mg/kg. The average Zn, Al, Mg, and Fe concentrations were within 0.2–163 g/kg. The highest concentrations of PM2.52.5 and PM1010, 258 and 387 µg/m3, respectively, were observed in the Pulverizer site. Forty-four workers had respiratory symptoms, 64 presented LFT abnormalities, 5 indicated chest irregularities, 35.98% were smokers, and 37.5% of workers with abnormal LFT results were smokers. The correlation coefficients between LFT results and work duration with respiratory symptoms and work duration and chest X-ray results were 0.022 and 0.011, respectively. In conclusion, most pulmonary disorders observed cannot directly correlate to Asbestos exposure due to negligible fibres in breathing air, but fibres in the depositions and dust can influence the pulmonary health of the employees. [ABSTRACT FROM AUTHOR]

In order to assess the geochemical effects of retrograde metamorphic rehydration, fluid metasomatism, and the fluid-mobile elements (FMEs) budget in the case of oceanic and continental subduction, we report the petrography, bulk, and in situ LA-ICP-MS trace-element data for the two poorly studied ophiolites in the northern (Khara-Nur, Eastern Sayan, Russia) and central (Alag-Khadny accretionary wedge, SW Mongolia) parts of the peri-Siberian orogenic framing. Both complexes are relics of the ancient oceanic mantle, which was subjected to processes of partial melting, metasomatism, and retrograde metamorphism. Typical mineral assemblages include olivine + orthopyroxene + chlorite + tremolite ± secondary olivine (640–800 °C), olivine + antigorite ± secondary clinopyroxene (<640 °C), and olivine + chrysotile ± secondary clinopyroxene (<250 °C) and are stable at pressures up to 2 GPa. Hydration and partial serpentinization of mantle peridotites lead to tremolite formation after orthopyroxene, followed by olivine replacement by antigorite. Serpentine-group minerals (antigorite and chrysotile) were distinguished by Raman spectroscopy, and the contents of incompatible elements (mobile and immobile in fluids) in metamorphic minerals (tremolite, antigorite, and chrysotile) were examined in situ by LA-ICP-MS. The behavior of conservative HFSE (Zr, Nb, Ta, and Ti) and—in part—HREE does not distinguish between the two types (oceanic and continental) of subduction environments. Different patterns of FMEs (Cs, Rb, Ba, U, Sb, Pb, Sr, and LREE) enrichment in metaperidotites reflect variations in the slab fluid composition, which was primarily governed by the contrasting nature of subducted lithologies. The affinity of Alag-Khadny to the subduction of a continental margin is recorded by increased FME contents and selective enrichment by some moderately mobile elements, such as U, Th, and LREE, with respect to the oceanic-type subduction environment of Khara-Nur. Distinct patterns of FME enrichment in tremolite and antigorite from two complexes indicate different sequences of fluid-induced replacement, which was controlled by Opx composition. We demonstrate that evaluation of the initial composition of precursor minerals affected by multi-stage melting and melt metasomatism should be considered with care to estimate the differential fluid overprint and associated elemental uptake from subduction fluids. [ABSTRACT FROM AUTHOR]

Erionite is a naturally occurring fibrous mineral found in soils in some geographical regions. Known for its potency for causing mesothelioma in the Cappadocia region of Turkey, the erionite fiber has attracted interest in the United States due to its presence in a band of rock that extends from Mexico to Montana. There are few toxicology studies of erionite, but all show it to have unusually high chronic toxicity. Despite its high potency compared to asbestos fibers, erionite has no occupational or environmental exposure limits. This paper takes what has been learned about the chemical and physical characteristics of the various forms of asbestos (chrysotile, amosite, anthophyllite, and crocidolite) and predicts the potency of North American erionite fibers. Based on the fiber potency model in Korchevskiy et al. (2019) and the available published information on erionite, the estimated mesothelioma potency factors (the proportion of mesothelioma mortality per unit cumulative exposure (f/cc-year)) for erionites in the western United States were determined. The model predicted potency factors ranged from 0.19 to 11.25 (average ∼3.5), depending on the region. For reference, crocidolite (the most potent commercial form of asbestos) is assigned a potency factor ∼0.5. The model predicted mesothelioma potency of Turkish erionite (4.53) falls in this same range of potencies as erionite found in North America. Although it can vary by region, a reasonable ratio of average mesothelioma potency based on this model is 3,000:500:100:1 comparing North American erionite, crocidolite, amosite, and chrysotile (from most potent to least potent). [ABSTRACT FROM AUTHOR]

The three main serpentine minerals, chrysotile, lizardite, and antigorite, form in various geological settings and have different chemical compositions and rheological properties. The accurate identification of serpentine minerals is thus of fundamental importance to understanding global geochemical cycles and the tectonic evolution of serpentine-bearing rocks. However, it is challenging to distinguish specific serpentine species solely based on geochemical data obtained by traditional analytical techniques. Here, we apply machine learning approaches to classify serpentine minerals based on their chemical compositions alone. Using the Extreme Gradient Boosting (XGBoost) algorithm, we trained a classifier model (overall accuracy of 87.2%) that is capable of distinguishing between low-temperature (chrysotile and lizardite) and high-temperature (antigorite) serpentines mainly based on their SiO2, NiO, and Al2O3 contents. We also utilized a k-means model to demonstrate that the tectonic environment in which serpentine minerals form correlates with their chemical compositions. Our results obtained by combining these classification and clustering models imply the increase of Al2O3 and SiO2 contents and the decrease of NiO content during the transformation from low- to high-temperature serpentine (i.e., lizardite and chrysotile to antigorite) under greenschist–blueschist conditions. These correlations can be used to constrain mass transfer and the surrounding environments during the subduction of hydrated oceanic crust. [ABSTRACT FROM AUTHOR]

Asbestos has been used extensively in the construction industry for its superior insulation properties before its health hazards were discovered and its use eventually banned. It is likely that many residential buildings built before the 2000s in Turkey contain asbestos. Therefore, it is important to raise awareness of the potential danger of asbestos exposure during demolition work and to identify asbestos-containing materials and ensure their safe removal and disposal. This study is executed to determine the residential dwellings containing asbestos in Izmir, Turkey. The research included field studies to determine asbestos presence in the buildings that were damaged during the 2020 earthquake. Air measurements and bulk samples were taken from 50 buildings that would go through the demolition process. Eleven buildings were found to contain asbestos which corresponds to 22%. The detected asbestos type was 60% chrysotile (white asbestos). Results could be helpful for future demolition work, which are conducted in the same region that includes buildings with similar properties. Also, it is expected that the database created for this study could be useful in other studies in Turkey, where accurate statistical data related with asbestos measurements is essentially non-existent. [ABSTRACT FROM AUTHOR]

Abstract Background Asbestos lung content is regarded as the most reliable tool for causal attribution of malignant mesothelioma (MM) to previous asbestos exposures. However, there is a lack of studies on asbestos burden in lungs of MM patients in comparison with healthy individuals. This study aims to provide such a comparison, investigating, as well, differences in asbestos lung burden with sex and time trends. Methods Asbestos lung content has been assessed on formalin-fixed lung fragments using scanning electron microscopy coupled with energy dispersion spectroscopy (SEM–EDS) on individuals deceased from MM (cases) and healthy subjects without any lung disease who died from violent causes (controls) between 2005 and 2023. Results Asbestos and asbestos bodies (ABs) were found, respectively, in 73.7% and 43.2% of cases and in 28 and 22% of controls; in MM cases the most represented asbestos types were crocidolite and amosite, whereas in controls it was tremolite-actinolite asbestos. The concentration of both asbestos fibers and ABs was statistically significantly higher in MM cases compared to controls. The mean asbestos fibers width was also significantly higher in cases than controls. Males and females with MM showed similar asbestos and ABs concentrations, but females had higher concentrations of chrysotile, and significantly lower fibers width compared to males. Time trends show that MM lung asbestos concentrations decreased starting in 2011. Discussion The results suggest a correlation between asbestos burden in lungs and MM risk. The different concentration of chrysotile, as well as the different width of asbestos fibers in MM males and females might reflect a sex difference in response of the lung microenvironment to inhaled asbestos. Finally, this study provides the first pathological evidence of the effect of the ban of asbestos use, demonstrating a significant decrease of asbestos lung content after 2011.

Serpentines are geologically important minerals, and antigorite (Atg), lizardite (Lz) and chrysotile (Ctl) are the three key varieties. Their quick and accurate identification with micro-Raman spectroscopy requires to consider the effects of different crystallographic orientations and different chemical compositions. By collecting from existing literatures all Raman spectroscopic data and compositional data acquired from the same or identical Atg, Lz and Ctl samples, we critically examined the compositional effects for the first time, and found that some compositional parameters like the Al2O3 and Cr2O3 contents have significant impacts on the Raman features. Taking into account the effects of both compositional difference and crystallographic orientation difference, we propose two identification schemes for Atg, Lz and Ctl: the first one uses those weak but characteristic Raman peaks at 1200–1000 cm−1, and the second one uses those intense and unanimously-observed Raman peaks at ∼688, 378 and 229 cm−1. As for the first identification scheme, no peak at 1200–1000 cm−1 suggests the presence of Lz; a single peak at ∼1045, at ∼1070, or at ∼1106 cm−1 indicates the presence of Atg, Lz, or Ctl, respectively; two Raman peaks at ∼1040 and 1070 cm−1 implies the presence of Lz; the occasionally observed one single peak at ∼1040 cm−1 may imply the presence of either Atg or Lz, which can be sought out by resorting to the peak position ratio R∼1045/688 (Atg having R∼1045/688 > ∼1.521 whereas Lz attaining R∼1045/688

Abstract Background Asbestos is a mineral present in nature and it has been used for years in numerous settings. Asbestos enters the bloodstream and lymphatic system mainly through breathing. Objectives Studies with asbestos fiber’s quantification in human tissues are scarce except for the lung. This article summarizes asbestos studies in some extra-abdominal tissues. Methods A scoping review of articles that quantified asbestos fibers in extra-abdominal tissues (lymph nodes, pharynx, larynx, trachea, heart) by electron microscopy (Scanning—SEM or Transmission—TEM) was performed. Results The 10 studies selected comprised 52 cases, out of whom 108 samples were analyzed. Mostly samples were lymph node tissues (102), followed by larynx (3) and myocardium (3). No studies were found that determined the presence of asbestos in the pharynx or trachea. The concentration of asbestos fibers detected in the lymph nodes was from 0.003 million fibers per gram of dry tissue (mfgdt) up to 7400 mfgdt, in the larynx the range was from 0.5 mfgdt up to 3.6 mfgdt, in myocardium no asbestos fibers were detected. Discussion The studies included were heterogeneous in terms of case and sample characteristics and analytical techniques. As subjects exposed to asbestos are often positive for fibers in thoracic lymph nodes, we suggest that whenever a human tissue sample is analyzed for asbestos presence, the relevant draining lymph node should be concomitantly studied.

As a mineral material widely used in life, chrysotile is a public health concern for its fibrogenicity and carcinogenicity. Currently, more than 50 countries have completely banned the import and use of chrysotile, but China is still the world's largest consumer and second largest producer of chrysotile, with a large occupationally exposed population. Investigations have shown that chrysotile miners are significantly more likely to develop pulmonary fibrosis, lung cancer, and mesothelioma than workers in other occupations. Chrysotile-induced cancers generally have a decades-long latency period and are difficult to diagnose and treat in a timely manner. Therefore, the cancer fatality due to chrysotile exposure is significant and is a leading contributor to occupational cancer death. Epithelial mesenchymal transition is a key step in the biological processes of chronic inflammation, fibrosis, carcinogenesis, and cancer metastasis in tissues and organs, also plays an important role in pulmonary fibrosis, lung cancer, and other diseases due to chrysotile exposure. This paper summarized the mechanisms of chrysotile inducing epithelial interstitial transition from dynamics of inflammatory factors, mitogen-activated protein kinase pathways, oxidative stress, and other biological pathways, and proposed possible research directions for further study on chrysotile-induced epithelial mesenchymal transition, aiming to provide a reliable basis and reference for in-depth research on pulmonary fibrosis, lung cancer, and other diseases due to chrysotile exposure.

Studies of magnesium (Mg) isotope ratios in subduction zone lavas have revealed small, but significant offsets from the mantle value with enrichments in the heavy isotopes. However, the very high concentration of Mg in the mantle contrasts with much lower concentrations in the subducted igneous crust and oceanic sediments, making these subduction components unlikely vehicles of the Mg isotope anomalies in arc lavas. Only serpentinites, which in various proportions form part of oceanic plates, have high Mg contents comparable to fresh mantle rocks and have thus been considered a potential source of exotic Mg in the source of arc magmas. In this study we analyzed serpentinite samples from different oceanic settings for their Mg isotopic compositions. The majority of samples are indistinguishable from the depleted mantle (δ26Mg = −0.24 ± 0.04 ‰) irrespective of their origin. Only a small number of seafloor-weathered serpentinites are slightly enriched in the heavy isotopes (up to δ26Mg = −0.14 ± 0.03 ‰), implying that bulk serpentinites are unlikely sources of isotopically anomalous Mg in subduction zones. We also developed a partial-dissolution method in which 5 % acetic acid for 180 minutes was shown to fully dissolve the minerals brucite and iowaite while leaving the serpentine mineral chrysotile essentially undissolved. Partial dissolution of 11 bulk serpentinite samples revealed a Mg isotopic composition of brucite (±iowaite) that is systematically ~0.25 ‰ heavier than that of coexisting serpentine. Thus, preferential breakdown of brucite and/or iowaite in a subducted slab prior to serpentine could preferentially release isotopically heavy Mg, which could subsequently be transported into the source region of arc magmas. Such a scenario would require brucite/iowaite breakdown to occur at pressures in excess of 3 GPa and produce fluids with very high concentrations of Mg that could be transported to arc magma source regions. Whether these conditions are met in nature has yet to be experimentally investigated. [ABSTRACT FROM AUTHOR]

Bioremediation utilizes living organisms such as plants, microbes and their enzymatic products to reduce toxicity in xenobiotic compounds. Microbial-mediated bioremediation is cost effective and sustainable and in situ application is easily implemented. Either naturally occurring metabolic activity can be utilized during bioremediation for the degradation, transformation or accumulation of substances, or microbial augmentation with non-native species can be exploited. Despite the perceived low potential for the biological degradation of some recalcitrant compounds, successful steps towards bioremediation have been made, including with asbestos minerals, which are prevalent in building stock (created prior to the year 2000) in New Zealand. Evidence of the in situ biodegradation of asbestos fibres was investigated in samples taken from a retired asbestos mine, asbestos-contaminated soils and biofilm or lichen-covered asbestos-containing building materials. Microbial diversity within the biofilms to be associated with the asbestos-containing samples was investigated using internal transcribed spacer and 16S DNA amplicon sequencing, supplemented with isolation and culturing on agar plates. A range of fungal and bacterial species were found, including some known to produce siderophores. Changes to fibre structure and morphology were analysed using Transmission Electron Microscopy and Energy-Dispersive X-ray Spectroscopy. Chrysotile fibrils from asbestos-containing material (ACMs), asbestos-containing soils, and asbestos incorporated into lichen material showed signs of amorphisation and dissolution across their length, which could be related to biological activity. [ABSTRACT FROM AUTHOR]

We report the formation of minerals from the tochilinite-valleriite group (TVG) during laboratory serpentinization experiments conducted at 300 and 328 °C. Minerals in the TVG are composed of a mixture of sulfide and hydroxide layers that can contain variable proportions of Fe, Mg, Cu, Ni, and other cations in both layers. Members of this group have been observed as accessory minerals in several serpentinites, and have also been observed in association with serpentine minerals in meteorites. To our knowledge, however, TVG minerals have not previously been identified as reaction products during laboratory simulation of serpentinization. The serpentinization experiments reacted olivine with artificial seawater containing 34S-labeled sulfate, with a small amount of solid FeS also added to the 300 °C experiment. In both experiments, the predominant reaction products were chrysotile serpentine, brucite, and magnetite. At 300 °C, these major products were accompanied by trace amounts of the Ni-bearing TVG member haapalaite, Ni,Fe-sulfide (likely pentlandite), and anhydrite. At 328 °C, valleriite occurs rather than haapalaite and the accompanying Ni,Fe-sulfide is proportionally more enriched in Ni. Reduction of sulfate by H2 produced during serpentinization evidently provided a source of reduced S that contributed to formation of the TVG minerals and Ni,Fe-sulfides. The results provide new constraints on the conditions that allow precipitation of tochilinite-valleriite group minerals in natural serpentinites. [ABSTRACT FROM AUTHOR]

Background The association between asbestos exposure and ovarian cancer has been questioned given the possible misdiagnosis of peritoneal mesothelioma as ovarian cancer. Aims To update a systematic review on ovarian cancer risk in women occupationally exposed to asbestos, exploring the association with the time since first exposure and the duration of exposure. Methods We searched PubMed from 2008 onwards, screened previous systematic reviews, combined standardized mortality ratios (SMR) using random effect models and quantified heterogeneity using the I 2 statistic. To assess tumour misclassification, we compared the distribution of observed excess ovarian cancers (OEOC) to that expected (EEOC) from the distribution of peritoneal cancers in strata of latency and exposure duration. Results Eighteen publications (20 populations), including a pooled analysis of 21 cohorts, were included. The pooled SMR was 1.79 (95% confidence interval 1.38–2.31), with moderate heterogeneity between studies (I 2 = 42%), based on 144 ovarian cancer deaths/cases. The risk was increased for women with indirect indicators of higher exposure, longer duration and latency, and lower for chrysotile than for crocidolite exposure. The effect of duration and latency could not be completely disentangled, since no multivariate analysis was available for time-related variables. The dissimilarity index between OEOC and EEOC for the time since first exposure was small suggesting a similar pattern of risk. Conclusions While some misclassification between ovarian and peritoneal cancers cannot be excluded, the observed excess risk of ovarian cancer should be added to the overall disease burden of asbestos. [ABSTRACT FROM AUTHOR]

Background: Asbestos lung content is regarded as the most reliable tool for causal attribution of malignant mesothelioma (MM) to previous asbestos exposures. However, there is a lack of studies on asbestos burden in lungs of MM patients in comparison with healthy individuals. This study aims to provide such a comparison, investigating, as well, differences in asbestos lung burden with sex and time trends. Methods: Asbestos lung content has been assessed on formalin-fixed lung fragments using scanning electron microscopy coupled with energy dispersion spectroscopy (SEM–EDS) on individuals deceased from MM (cases) and healthy subjects without any lung disease who died from violent causes (controls) between 2005 and 2023. Results: Asbestos and asbestos bodies (ABs) were found, respectively, in 73.7% and 43.2% of cases and in 28 and 22% of controls; in MM cases the most represented asbestos types were crocidolite and amosite, whereas in controls it was tremolite-actinolite asbestos. The concentration of both asbestos fibers and ABs was statistically significantly higher in MM cases compared to controls. The mean asbestos fibers width was also significantly higher in cases than controls. Males and females with MM showed similar asbestos and ABs concentrations, but females had higher concentrations of chrysotile, and significantly lower fibers width compared to males. Time trends show that MM lung asbestos concentrations decreased starting in 2011. Discussion: The results suggest a correlation between asbestos burden in lungs and MM risk. The different concentration of chrysotile, as well as the different width of asbestos fibers in MM males and females might reflect a sex difference in response of the lung microenvironment to inhaled asbestos. Finally, this study provides the first pathological evidence of the effect of the ban of asbestos use, demonstrating a significant decrease of asbestos lung content after 2011. [ABSTRACT FROM AUTHOR]

Background: Asbestos is a mineral present in nature and it has been used for years in numerous settings. Asbestos enters the bloodstream and lymphatic system mainly through breathing. Objectives: Studies with asbestos fiber's quantification in human tissues are scarce except for the lung. This article summarizes asbestos studies in some extra-abdominal tissues. Methods: A scoping review of articles that quantified asbestos fibers in extra-abdominal tissues (lymph nodes, pharynx, larynx, trachea, heart) by electron microscopy (Scanning—SEM or Transmission—TEM) was performed. Results: The 10 studies selected comprised 52 cases, out of whom 108 samples were analyzed. Mostly samples were lymph node tissues (102), followed by larynx (3) and myocardium (3). No studies were found that determined the presence of asbestos in the pharynx or trachea. The concentration of asbestos fibers detected in the lymph nodes was from 0.003 million fibers per gram of dry tissue (mfgdt) up to 7400 mfgdt, in the larynx the range was from 0.5 mfgdt up to 3.6 mfgdt, in myocardium no asbestos fibers were detected. Discussion: The studies included were heterogeneous in terms of case and sample characteristics and analytical techniques. As subjects exposed to asbestos are often positive for fibers in thoracic lymph nodes, we suggest that whenever a human tissue sample is analyzed for asbestos presence, the relevant draining lymph node should be concomitantly studied. [ABSTRACT FROM AUTHOR]

Asbestos is a known carcinogen; however, the influence of chrysotile asbestos on the development of tumor-related diseases remains a subject of intense debate within the scientific community. To analyze the effect of asbestos, we conducted a study using the MRC5 cell line. We were able to demonstrate that chrysotile asbestos stimulated the production of reactive oxygen species (ROS), leading to cell death and DNA damage in the MRC5 cell line, using various techniques such as ROS measurement, comet assay, MTT assay, and qPCR. In addition, we found that chrysotile asbestos treatment significantly increased extracellular mitochondrial DNA levels in the culture medium and induced significant changes in the expression profile of several miRNAs, which was the first of its kind. Thus, our research highlights the importance of studying the effects of chrysotile asbestos on human health and reveals multiple adverse effects of chrysotile asbestos. [ABSTRACT FROM AUTHOR]

This analysis updates two previous analyses that evaluated the exposure-response relationships for lung cancer and mesothelioma in chrysotile-exposed cohorts. We reviewed recently published studies, as well as updated information from previous studies. Based on the 16 studies considered for chrysotile (<10% amphibole), we identified the "no-observed adverse effect level" (NOAEL) for lung cancer and/or mesothelioma; it should be noted that smoking or previous or concurrent occupational exposure to amphiboles (if it existed) was not controlled for. NOAEL values ranged from 2.3–<11.5 f/cc-years to 1600–3200 f/cc-years for lung cancer and from 100–<400 f/cc-years to 800–1599 f/cc-years for mesothelioma. The range of best-estimate NOAELs was estimated to be 97–175 f/cc-years for lung cancer and 250–379 f/cc-years for mesothelioma. None of the six cohorts of cement or friction product manufacturing workers exhibited an increased risk at any exposure level, while all but one of the six studies of textile workers reported an increased risk at one or more exposure levels. This is likely because friction and cement workers were exposed to much shorter chrysotile fibers. Only eight cases of peritoneal mesothelioma were reported in all studies on predominantly chrysotile-exposed cohorts combined. This analysis also proposed best-estimate amosite and crocidolite NOAELs for mesothelioma derived by the application of relative potency estimates to the best-estimate chrysotile NOAELs for mesothelioma and validated by epidemiology studies with exposure-response information. The best-estimate amosite and crocidolite NOAELs for mesothelioma were 2–5 f/cc-years and 0.6–1 f/cc-years, respectively. The rate of peritoneal mesothelioma in amosite- and crocidolite-exposed cohorts was between approximately 70- to 100-fold and several-hundred-fold higher than in chrysotile-exposed cohorts, respectively. These findings will help characterize potential worker and consumer health risks associated with historical and current chrysotile, amosite, and crocidolite exposures. [ABSTRACT FROM AUTHOR]

Background: Quantification of asbestos fibers has been mainly performed in the lung but rarely in other organs. However, this may be relevant to understanding better translocation pathways and the oncogenic effects of asbestos on the human body. Electron microscopy is the best technology available to assess the type of fiber, dimensions, and distribution of asbestos fibers in different tissues and as a biomarker of cumulative dose. Objectives: This scoping review aims to summarize the findings of the studies in which asbestos fibers have been quantified by electron microscopy, occasionally associated with X-ray microanalysis, in normal and pathological tissue of ten abdominal organs. Methods: A scoping review has been performed by searching articles that quantified asbestos fibers in abdominal organs by electron microscopy (Scanning-SEM or Transmission-TEM). Results: The colon and rectum, kidney, bladder, and abdominal lymph nodes were the organs with at least ten samples available with quantification of asbestos fibers. Asbestos fibers were detected in all the abdominal organs considered: the highest value (152,32 million fibers per gram of dry tissue) was found in the colon and was identified using STEM with EDS. Conclusion: The studies included were heterogeneous in terms of exposure and cases, type of samples, as well as analytical techniques, therefore we cannot confirm a specific pattern of distribution in any organ, based on the low homogeneity of the exposure status. The colon is the organ in which the number of fibers is the highest, probably because of exposure arising from both internal distribution of inhaled fibers and ingestion. Additional studies of the number of asbestos fibers in abdominal organs should be made to achieve better representativity. [ABSTRACT FROM AUTHOR]

Asbestos mining in Zimbabwe left vast tracts of unrehabilitated land characterised by heaps of potentially carcinogenic tailings dumps. The research sought to trace the abandoned mines' environmental footprint, establish the tailings' tonnage, and explore the possibility of resuscitation against repurposing one of the prominent Gaths Mines for recovery of metals from the tailings. The mine has been under closure for two decades. the research findings indicated that over 2600km2 of land has potentially been contaminated by asbestos tailings within the abandoned Gaths Mines. The research concluded that resuscitating Gaths mines for asbestos extraction was not feasible given the international scrutiny on asbestos as a hazardous substance. However, after confirming that the Gaths mines hosts over 140 million tonnes of asbestos with 40.3% Mg content and traces of platinum group metals and Al among other recoverable metals, the research concluded that repurposing the site was feasible. The overall estimate for the capex for a 50 000t/pa Mg Plant 25-year project was estimated at US$416,7 million against an estimated net cash flow of US$1 billion. The NPV for the project was estimated to exceed US$95,5 million at a discount rate of 10%. The project’s Internal Rate of Return was estimated at 16.14%. Overall, the research concluded that the site can potentially be converted from a liability to a legacy that will transform the host communities toward the creation of a sustainable city in Mashava, Zimbabwe.

We have studied the effect of the composition of starting Mg1– хNiх(OH)2 nanoplates on the formation of (Mg1– хNiх)3Si2O5(OH)4 nanoscrolls under hydrothermal conditions and determined the structure, morphology, size parameters, and specific surface area of the synthesized nanopowders based on (Mg1– хNiх)3Si2O5(OH)4 hydrosilicates with the chrysotile structure. The thermodynamically driven dehydration of the starting (Mg1– хNiх)(OH)2 hydroxide with х ≳ 0.4 during hydrothermal treatment of a mixture of magnesium nickel hydroxide nanoplates and silica gel (SiO2∙nH2O) particles dispersed in an aqueous sodium hydroxide solution has been shown to play a key role in determining the formation and structural characteristics of (Mg1– хNiх)3Si2O5(OH)4 nanopowders with tubular structure. [ABSTRACT FROM AUTHOR]