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Comparative tests of the following fibers are conducted under the same conditions: mineral (basalt, glass), carbon, chemical (polycaproamide, polyacrylonitrile, viscose fibers), and vegetable (bast fibers of linen, hemp, nettle). The diameter of a monofiber, linear density, breaking strength of a roving (a bundle of fibers) and microplastics, breaking tenacity, and gain ratio are assessed. Glass and basalt fibers have the highest linear density of 1200–2500 tex; carbon, 378 tex; chemical, 183 tex (except for PANF, which has 826 tex); and bast vegetable fibers, 440–630 tex. The breaking tenacity for glass rovings and basalt rovings is comparable of 240–264 mN/tex and is the highest of 597 mN/tex for carbon rovings; the gain ratio is 2–2.25. For chemical fibers, the breaking tenacity is 282–323 mN/tex (92 mN/tex in viscose ones) and the gain ratio is 0.5–0.9. Of vegetable fibers, the highest breaking strength of 93–102 mN/tex is in the fibers of linen and hemp, which exceeds this parameter for a viscose fiber; the gain ratio is 1.6 in hemp and 4.39 in linen. In fibers of nettle, the results are the lowest among vegetable fibers. [ABSTRACT FROM AUTHOR]

In this article, we review the existing types of binders for thermal and acoustic insulation made of glass and mineral fibers. The current interest in the development and modification of binders for the manufacture of thermal insulation used in the transport, construction, and other industrial sectors is associated with increased requirements for their operational, environmental, and fire-retardant characteristics. Directions in the development of binders for fiber thermal insulation materials that meet modern requirements are indicated. Thus, thermal protection systems should possess sufficient strength and flexibility to maintain their integrity during manufacture, transportation, and installation in target volumes, as well as sufficient elasticity to restore their volume after compression, low specific gravity, low coefficient of thermal conductivity, flame resistance, low smoke emission, and resistance to moisture gain during heating and cooling. [ABSTRACT FROM AUTHOR]

Using computer physicochemical modeling methods, we determine the mineral compositions of igneous rocks corresponding to latite and trachyte, medium volcanic rocks of the subalkaline series 53 ≤ SiO2 ≤ 64.5 ≤ (Na2O + K2O) ≤ 14. The possibility of modifying the mineral composition of these rocks to enable their use as raw materials for the production of stone ceramics, stone-casting products, and mineral fibers is established. [ABSTRACT FROM AUTHOR]

During a Loss Of Coolant Accident involving a primary circuit failure in a nuclear power plant, debris, generated by the impact of the steam jet, is transported to the hot liquid phase formed at the bottom of the nuclear containment. Water is recirculated after passing through filters. Chemicals are released and may precipitate on the filters, increasing the pressure drop. This paper investigates the characterization of precipitate formation in a soda/borate buffer, due to the presence of calcium, silicon, and zinc, released from mineral fibers, concrete particles, or the corrosion of metal surfaces. Experiments run at various temperatures and chemical compositions are presented, with the objective of identifying the precipitates and determining the critical thresholds of concentration and temperature beyond which the risk of chemical clogging disappears. The experimental results are compared to those calculated with the CHESS software, intended to calculate the speciation at thermodynamic equilibrium. The results show the formation of amorphous precipitates: silica, calcium borates, borosilicates and zinc silicate. Precipitation is temperature dependent, with the highest masses obtained between 50 and 60 °C. The comparison of experimental and calculated results indicates a good overall consistency. This work demonstrates the importance of considering chemical clogging in this context. [Display omitted] • Chemical effects on of sump filter clogging in LOCA situations are studied. • The precipitates are silica, calcium borate, borosilicate and zinc silicates. • Precipitation is influenced by temperature and is maximal around 60 °C. • Speciation calculations (CHESS) predict the experimental results fairly well. • Chemical effects contribute to the clogging of PWR sumps. [ABSTRACT FROM AUTHOR]

Mineral fibre composites are widely employed in a variety of industries due to their superior qualities over other fibres. Mineral fibres have proven to be effective in a variety of applications, including electronics, aviation, medical, maritime, cars, and concrete structural elements. Glass and basalt fibres are the most often utilized mineral fibres in polymer composites. Various researchers have recently attempted to improve the properties of composite materials by hybridizing fibre reinforced composites with nano fillers. The fillers have a high aspect ratio due to their nanosize dimension, which provides more surface area for interaction with the matrix material. When these nanoparticles are utilized as a reinforcement in mineral fiber-based composites, they exhibit outstanding qualities that meet industry standards. This study provides a brief overview of the most commonly utilized mineral fibres in polymer composites, as well as nano filler-based polymer hybrid composites and their current developments. [ABSTRACT FROM AUTHOR]

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Mineral oxide fibers of various chemical compositions are reviewed: aluminosilicate, alumina, silica, biosoluble, fibers made from zirconium oxide, and others. Methods for manufacturing discrete and continuous fibers are given, such as spinning fibers from melts, sol-gel technology, spinning from solutions of metal salts, and others. The physicochemical characteristics of mineral fibers are described and their applications are indicated, such as thermal insulation up to 1150 or 1000°C and high temperature filtration for aluminosilicate and biosoluble fibers; thermal insulation up to 1600 or 2000°C, and reinforcement of composites used in the aerospace and defense industries for alumina fibers and fibers based on zirconium dioxide, and so on. Manufacturers of mineral oxide-containing fibers and products based on them in and outside of Russia are indicated. [ABSTRACT FROM AUTHOR]

This study explored morphological, mineralogical, and physicochemical features of suspected toxic mordenite fibers from Northern Italy. All the mordenite samples (FAS1, GC1, SP1) show similar structural and chemical character, are Na-rich (Na > Ca > K), and the Al content decrease reflects the unit cell volumes in the series: FAS1 > SP1 > GC1. The aerodynamic diameter (Dae) values of the mordenite fibers are 1.19 μm for the GC1 sample, 2.69 μm for FAS1, and 3.91 μm for SP1. All the studied mordenite samples are characterized by "respirable" fibers despite the size differences, which could reach the deeper parts of the lungs. For this reason, fibrous mordenite could represent a potential health hazard and then need to be handled with attention, but further toxicity studies are needed. [ABSTRACT FROM AUTHOR]

Objectives: Pleural mesothelioma is a rare respiratory cancer, mainly caused by inhalation of asbestos fibres. Other inorganic fibres are also suggested risk factors. We aimed to investigate the association between exposure to asbestos or refractory ceramic fibres (RCFs) and pleural mesothelioma among male Norwegian offshore petroleum workers., Methods: Among 25 347 men in the Norwegian Offshore Petroleum Workers (NOPW) cohort (1965-1998), 43 pleural mesothelioma cases were identified through the Cancer Registry of Norway (1999-2022). A case-cohort study was conducted with 2095 randomly drawn non-cases from the cohort. Asbestos and RCF exposures were assessed with expert-made job-exposure matrices (JEMs). Weighted Cox regression was used to estimate HRs and 95% CIs, adjusted for age at baseline and pre-offshore employment with likely asbestos exposure., Results: An increased risk of pleural mesothelioma was indicated for the highest versus lowest tertile of average intensity of asbestos (HR=1.21, 95% CI: 0.57 to 2.54). Pre-offshore asbestos exposure (vs no such exposure) was associated with increased risk of pleural mesothelioma (HR=2.06, 95% CI: 1.11 to 3.81). For offshore workers with no pre-offshore asbestos exposure, an increased risk of pleural mesothelioma was found for the highest tertile of average intensity of asbestos (HR=4.13, 95% CI: 0.93 to 18), versus the lowest tertile. No associations were found between RCF and pleural mesothelioma., Conclusions: Associations between JEM-based offshore asbestos exposure and pleural mesothelioma were confirmed in the NOPW cohort. Pleural mesothelioma risk was also associated with asbestos exposure before work in the offshore petroleum industry., Competing Interests: Competing interests: The authors declare that they have no financial or other relationships that might lead to a conflict of interest. However, coauthors TKG and JSS have received funding from the Research Council of Norway (governmental agency) in the form of an industry-collaborative grant to the Cancer Registry of Norway (governmental agency) in 2019, to establish an enlarged cohort of offshore petroleum workers. A condition pertaining to such industry-collaborative grants is that 20% (US$175 000) of the grant was provided by the petroleum industry and 80% (US$700 000) from State funding by the Research Council itself with the intention of joining forces for the common interest of occupational health among petroleum workers. The application process was governed by the Research Council alone without any involvement from the petroleum industry. The grant does not cover the salary of the PIs or any of the employees at collaborating institutions., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

A variety of actively precipitating mineral environments preserve morphological evidence of microbial biosignatures. One such environment with preserved microbial biosignatures is the oxidized portion of a massive sulfide deposit, or gossan, such as that at Iron Mountain, California. This gossan may serve as a mineralogical analogue to some ancient martian environments due to the presence of oxidized iron and sulfate species, and minerals that only form in acidic aqueous conditions, in both environments. Evaluating the potential biogenicity of cryptic textures in such martian gossans requires an understanding of how microbial textures form biosignatures on Earth. The iron-oxide-dominated composition and morphology of terrestrial, nonbranching filamentous microbial biosignatures may be distinctive of the underlying formation and preservation processes. The Iron Mountain gossan consists primarily of ferric oxide (hematite), hydrous ferric oxide (HFO, predominantly goethite), and jarosite group minerals, categorized into in situ gossan, and remobilized iron deposits. We interpret HFO filaments, found in both gossan types, as HFO-mineralized microbial filaments based in part on (1) the presence of preserved central filament lumina in smooth HFO mineral filaments that are likely molds of microbial filaments, (2) mineral filament formation in actively precipitating iron-oxide environments, (3) high degrees of mineral filament bending consistent with a flexible microbial filament template, and (4) the presence of bare microbial filaments on gossan rocks. Individual HFO filaments are below the resolution of the Mars Curiosity and Mars 2020 rover cameras, but sinuous filaments forming macroscopic matlike textures are resolvable. If present on Mars, available cameras may resolve these features identified as similar to terrestrial HFO filaments and allow subsequent evaluation for their biogenicity by synthesizing geochemical, mineralogical, and morphological analyses. Sinuous biogenic filaments could be preserved on Mars in an iron-rich environment analogous to Iron Mountain, with the Pahrump Hills region and Hematite Ridge in Gale Crater as tentative possibilities.

Exposure to asbestos fibers is associated with non-neoplastic pleural diseases including plaques, fibrosis, and benign effusions, as well as with diffuse malignant pleural mesothelioma. Translocation and retention of fibers are fundamental processes in understanding the interactions between the dose and dimensions of fibers retained at this anatomic site and the subsequent pathological reactions. The initial interaction of fibers with target cells in the pleura has been studied in cellular models in vitro and in experimental studies in vivo. The proposed biological mechanisms responsible for non-neoplastic and neoplastic pleural diseases and the physical and chemical properties of asbestos fibers relevant to these mechanisms are critically reviewed. Understanding mechanisms of asbestos fiber toxicity may help us anticipate the problems from future exposures both to asbestos and to novel fibrous materials such as nanotubes. Gaps in our understanding have been outlined as guides for future research.

Nowadays, research studies about optimal application of natural resources in products manufacturing instead of fossil and non-renewable resources are of utmost and ever growing importance. Cellulosic resources as the future reliance of Green products and also mineral mines as plenty, cheap and available materials, especially in Iran, are appropriate options for various products developing. Then, effects of cellulosic fibers and Rockwool fibers (0.25% and 0.5%) in the absence and presence (0.1% and 0.2%) of nano bentonite on conventional and specific properties of Epoxy composite were evaluated. Tensile strength (47.9 MPa), modulus of rupture (86.3 MPa) and modulus of elasticity (2100 MPa) for the mineral fiber/epoxy composite and bentonite/epoxy nanocomposite were higher than the cellulosic fiber/epoxy composite. However, cellulosic fiber/epoxy composite showed higher energy absorption of the ballistic impact with lesser damage area caused by the impact than rockwool/epoxy composite which provide better protection against the ballistic impact. In the presence of nano bentonite particles into the epoxy resin context, rupture and elasticity moduli and tensile strength were dependent on the type and amounts of the additives with superiority of the mineral fibres/epoxy nanocomposite than the cellulosic fibers ones. In contrast, the composites energy absorption caused by the ballistic impact and its damaged area were more successful and favorable in cellulosic fibers than the mineral ones. Somehow that the highest absorbed energy of ballistic impact (60.7 J) and the least damaged area (10.7 cm2) were achieved by the highest application of cellulosic fibers (0.5%) and nano-bentonite (0.2%).

The processes of melting of different types of igneous rock constituting gabbro-basalt raw material are examined. The role of the main rock-forming elements in the formation of these melts for the production of mineral fibers and stone-cast articles is shown. Special attention is devoted to their influence on the viscosity and crystallizability of the production melts as well as iron—the only element present in two degrees of oxidation Fe(II) and Fe(III), which can participate, correspondingly, in the processes of Mg and Al isomorphism. Information is presented on the influence of the ratio of these oxides on the crystallization processes of mineral fibers and stone-cast articles. [ABSTRACT FROM AUTHOR]

Abstract Background The mechanisms by which mineral fibers induce adverse effects in vivo are still not well understood. The mechanisms of fiber dissolution in the lungs and subsequent release of metals in the extracellular/intracellular environment must be taken into account. Aim For the first time, the kinetics of release of metals during the acellular in vitro dissolution of chrysotile, crocidolite and fibrous erionite were determined. Methods In vitro acellular dissolution of chrysotile, crocidolite, and fibrous erionite-Na was conducted using a solution mimicking the phagolysosome environment active during the phagocytosis process (pH=4.5, at 37 °C). The kinetics of release of a representative selection of metals were determined over a period of three months. Results Despite the fact that the difference in Fe content between chrysotile and crocidolite is one order of magnitude, the much faster dissolution rate of chrysotile compared to crocidolite prompts greater release of available active surface Fe in the first weeks of the dissolution experiment and comparable amounts after 90 d. Such active iron may promote the formation of toxic hydroxyl radicals. The fast release of metals like Cr, Ni and Mn from chrysotile is also a source of concern whereas the release of V in solution is negligible. Conclusion Because chrysotile undergoes fast dissolution with respect to crocidolite and fibrous erionite, it behaves like a carrier that releases its metals' cargo in the lung environment, mimicking the phenomenon that explains the toxicity of nanoparticles. Hence, the toxicity paradigm of a non biodurable fiber like chrysotile should also take into account the release of toxic metals in the intracellular/extracellular medium during the rapid dissolution process. Graphical abstract fx1 Highlights • Metals released during the dissolution of asbestos and erionite fibers were determined. • Fast release of Cr, Ni and Mn from chrysotile is a source of concern. • The model of in vitro dissolution of nanoparticles may also apply to mineral fibers. • Rapid dissolution of the fibers prompts intracellular/extracellular release of toxic metals. • 'Fiber toxicity paradigm' should consider the release of toxic metals during dissolution. [ABSTRACT FROM AUTHOR]

Abstract Iron and its role as soul of life on Earth is addressed in this review as iron is one of the most abundant elements of our universe, forms the core of our planet and that of telluric (i.e., Earth-like) planets, is a major element of the Earth's crust and is hosted in an endless number of mineral phases, both crystalline and amorphous. To study iron at an atomic level inside the bulk of mineral phases or at its surface, where it is more reactive, both spectroscopy and diffraction experimental methods can be used, taking advantage of nearly the whole spectrum of electromagnetic waves. These methods can be successfully combined to microscopy to simultaneously provide chemical (e.g. iron mapping) and morphological information on mineral particles, and shed light on the interaction of mineral surfaces with organic matter. This review describes the crystal chemistry of iron-bearing minerals of importance for the environment and human health, with special attention to iron in toxic minerals, and the experimental methods used for their study. Special attention is devoted to the Fenton-like chain reaction involving Fe2+ in the formation of highly reactive hydroxyl radicals. The final part of this review deals with release and adsorption of iron in biological fluids, coordinative and oxidative state of iron and in vitro reactivity. To disclose the very mechanisms of carcinogenesis induced by iron-bearing toxic mineral particles, crystal chemistry and surface chemistry are fundamental for a multidisciplinary approach which should involve geo-bio-scientists, toxicologists and medical doctors. Graphical abstract fx1 Highlights • The role of iron as soul of life on Earth is seen from the geology perspective. • Crystal chemistry of iron-bearing minerals endangering human health is described. • The major experimental techniques used to study iron in minerals are described. • Fe2+ in asbestos promotes the formation of OH• via Fenton-like chain reactions. • Iron crystal-chemistry is the basis to disclose iron-related carcinogenesis. [ABSTRACT FROM AUTHOR]

Abstract Some mineral fibers represent a health hazard because they are classified as cancer-causing chemical/physical toxicants upon (chronic) dust inhalation. Although in the last decades they have been the subject of intensive multidisciplinary investigations, the mechanisms by which mineral fibers induce toxic and pathogenic adverse effects on human health and environment are not yet fully understood. The major intricacy of the biological approach that prevents the design of a conclusive shared model of behavior of mineral fibers in a biological system stems from their very nature with intrinsic variability in chemical, molecular, structural and morphometric parameters, biodurability and surface reactivity. This paper presents the first attempt to devise a quantitative predictive model of toxicity/pathogenicity of minerals fibers based on their physical/chemical and morphological parameters. Although the author is aware that all parameters should be measured in comparable in vivo systems that accurately simulate the lung and or pleural environment, this preliminary model was conceived to deliver a fiber potential toxicity/pathogenicity index (FPTI) to be integrated with the biological approach so to create a quantitative predictive model of behavior of mineral fibers in a biological system. The FPTI model is thought to be a predictive tool aimed at ranking the toxicity and pathogenicity potential of fibers like asbestos or unregulated/unclassified mineral fibers. It may eventually be applied to other materials like man-made synthetic fibers and elongated mineral particles (EMP). Work is in progress to revise and validate the model in joint collaboration with international competent organizations, and to deliver a FPTI model-based user-friendly code. Highlights • The FPTI model calculates the potential toxicity/pathogenicity of mineral fibers. • The model applies to asbestos, unclassified and synthetic fibers and possibly EMP. • Different toxicity potentials are found for amphibole, erionite and chrysotile. • FPTI was calculated for 'safe' mineral fibers such as wollastonite and sepiolite. [ABSTRACT FROM AUTHOR]

In nature, a huge number of unregulated minerals fibers share the same characteristics as asbestos and therefore have potential adverse health effects. However, in addition to asbestos minerals, only fluoro-edenite and erionite are currently classified as toxic/pathogenic agents by the International Agency for Research on Cancer (IARC). Mordenite is one of the most abundant zeolites in nature and commonly occurs with a fibrous crystalline habit. The goal of this paper is to highlight how fibrous mordenite shares several common features with the well-known carcinogenic fibrous erionite. In particular, this study has shown that the morphology, biodurability, and surface characteristics of mordenite fibers are similar to those of erionite and asbestos. These properties make fibrous mordenite potentially toxic and exposure to its fibers can be associated with deadly diseases such as those associated with regulated mineral fibers. Since the presence of fibrous mordenite concerns widespread geological formations, this mineral fiber should be considered dangerous for health and the precautionary approach should be applied when this material is handled. Future in vitro and in vivo tests are necessary to provide further experimental confirmation of the outcome of this work.

This paper presents general data on the diorite family: intermediate plutonic rocks in the normally and low alkaline rock subclass. Using quartz diorite from the Altai Mountains as an example, we analyze the feasibility of using methods developed at the Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, for modifying the composition of magmatic and metamorphic rocks for mineral fiber fabrication and stone casting. [ABSTRACT FROM AUTHOR]

Using picrobasalt from the Bulatovskoe occurrence (Arkhangelsk oblast) as an example, we analyze the feasibility of using methods developed at the Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, for modifying the composition of magmatic and metamorphic rocks for mineral fiber fabrication and stone casting. [ABSTRACT FROM AUTHOR]

In this work, hyperspectral imaging in the short wave infrared range (SWIR: 1000–2500 nm) coupled with chemometric techniques was evaluated as an analytical tool to detect and classify different asbestos minerals, such as amosite ((Fe 2+ ) 2 (Fe 2+ ,Mg) 5 Si 8 O 22 (OH) 2 )), crocidolite (Na 2 (Mg,Fe) 6 Si 8 O 22 (OH) 2 ) and chrysotile (Mg 3 (Si 2 O 5 )(OH) 4 ), contained in cement matrices. Principal Component Analysis (PCA) was used for data exploration and Soft Independent Modeling of Class Analogies (SIMCA) for sample classification. The classification model was built using spectral characteristics of reference asbestos samples and then applied to the asbestos containing materials. Results showed that identification and classification of amosite, crocidolite and chrysotile was obtained based on their different spectral signatures, mainly related to absorptions detected in the hydroxyl combination bands, such as Mg-OH (2300 nm) and Fe-OH (from 2280 to 2343 nm). The developed SIMCA model showed very good specificity and sensitivity values (from 0.89 to 1.00). The correctness of classification results was confirmed by stereomicroscopic investigations, based on different color, morphological and morphometrical characteristics of asbestos minerals, and by micro X-ray fluorescence maps, through iron (Fe) and magnesium (Mg) distribution assessment on asbestos fibers. The developed innovative approach could represent an important step forward to detect asbestos in building materials and demolition waste. [ABSTRACT FROM AUTHOR]

In this study, the phase transformation and micromorphology evolution of sepiolite fibers were studied along with the increase of temperature from 300 to 1300 °C, using raw sepiolite samples as raw materials. Through characterization by scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA/DTG) and differential scanning calorimeter (DSC), it was found that the determined transition temperature values for the dehydrations of the hygroscopic water and the zeolitic water were 120 °C and 340 °C, and the values for the dehydration of the bound water and the dehydroxylation of the hydroxyls were about 500 °C and 810 °C. Moreover, orthoenstatite (MgSiO 3 ) was recrystallized from dehydroxylated phase at 852 °C and then transformed into protoenstatite at 970 °C, and enstatite crystals grew along with c-axis of the fiber with the increase of temperature. Amorphous phase as the other phase of sepiolite dehydroxylation recrystallized into cristobalite in the temperature range of 1130–1200 °C and the samples began to melt at the above temperature range. In terms of morphology, both sepiolite bundles and laths remained constant after heating up to 1000 °C and sintering phenomenon appeared when the temperature was up to 1100 °C. The bundles partly melted and adhered each other, which further formed a porous structure after calcination at 1200 °C. When the temperature was up to 1300 °C, the sample substantially melted except for a small amount of enstatite and cristobalite crystals. The present study reflects the thermal reaction of sepiolite, which could be applied in exploring the reinforcement mechanism of sepiolite reinforced ceramic body composites. [ABSTRACT FROM AUTHOR]

The properties of andesite, a neutral or subalkaline medium volcanic rock, are reviewed. Using the example of andesite mined in Kamchatka, an analysis of the possibility of applying methods for modifying the composition of igneous rocks, which were developed at the Kurnakov Institute of General and Inorganic Chemistry, to the production of mineral fibers and stone casting has been made. [ABSTRACT FROM AUTHOR]

Mineral wool fibers can be released into the air during the production and handling of a mineral wool product where a small fraction of fibers will stay airborne and can potentially be inhaled. The aerodynamic fiber diameter determines how far an airborne fiber can pass through the human airway. Respirable fibers with an aerodynamic diameter < 3 µm can reach the deep part of the lungs (i.e., the alveolar region). Binder material (i.e., organic binder and mineral oil) is used in the production of mineral wool products. However, at the current stage, it is unknown if airborne fibers can contain binder material. We explored binder presence on airborne respirable fiber fractions being released and collected during the installation of two mineral wool products (a stone wool product and a glass wool product). Fiber collection was done by pumping a controlled air volume (2, 13, 22, and 32 l/min) through polycarbonate membrane filters during the installation of the mineral wool products. The morphological and chemical composition of the fibers were studied using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDXS) analysis. The study demonstrates that binder material is found on the surface of the respirable mineral wool fiber mainly as circular or elongated droplets. Our findings suggest that respirable fibers explored in previous epidemiological studies, which have been used for proving a lack of hazardous effects of mineral wool on humans, may have also contained binder materials on the fibers.

Erionite belonging to the zeolite family is a human health-hazard, since it was demonstrated to be carcinogenic. Conversely, offretite family zeolites were suspected carcinogenic. Mineralogical, morphological, chemical, and surface characterizations were performed on two erionites (GF1, MD8) and one offretite (BV12) fibrous samples and, for comparison, one scolecite (SC1) sample. The specific surface area analysis indicated a larger availability of surface sites for the adsorption onto GF1, while SC1 shows the lowest one and the presence of large pores in the poorly fibrous zeolite aggregates. Selected spin probes revealed a high adsorption capacity of GF1 compared to the other zeolites, but the polar/charged interacting sites were well distributed, intercalated by less polar sites (Si–O–Si). MD8 surface is less homogeneous and the polar/charged sites are more interacting and closer to each other compared to GF1. The interacting ability of BV12 surface is much lower than that found for GF1 and MD8 and the probes are trapped in small pores into the fibrous aggregates. In comparison with the other zeolites, the non-carcinogenic SC1 shows a poor interacting ability and a lower surface polarity. These results helped to clarify the chemical properties and the surface interacting ability of these zeolite fibers which may be related to their carcinogenicity. [ABSTRACT FROM AUTHOR]

Background: Exposure to asbestos is associated with malignant and nonmalignant respiratory disease. To strengthen the scientific basis for risk assessment on fibers, the National Institute of Environmental Health Sciences (NIEHS) has initiated a series of studies to address fundamental questions on the toxicology of naturally occurring asbestos and related mineral fibers after inhalation exposure. A prototype nose-only exposure system was previously developed and validated. The prototype system was expanded to a large-scale exposure system in this study for conducting subsequent in vivo rodent inhalation studies of Libby amphibole (LA) 2007, selected as a model fiber., Results: The exposure system consisting of six exposure carousels was able to independently deliver stable LA 2007 aerosol to individual carousels at target concentrations of 0 (control group), 0.1, 0.3, 1, 3, or 10 mg/m 3 . A single aerosol generator was used to provide aerosol to all carousels to ensure that exposure atmospheres were chemically and physically similar, with aerosol concentration as the only major variable among the carousels. Transmission electron microscopy (TEM) coupled with energy dispersive spectrometry (EDS) and selected area electron diffraction (SAED) analysis of aerosol samples collected at the exposure ports indicated the fiber dimensions, chemical composition, and mineralogy were equivalent across exposure carousels and were comparable to the bulk LA 2007 material., Conclusion: The exposure system developed is ready for use in conducting nose-only inhalation toxicity studies of LA 2007 in rats. The exposure system is anticipated to have applicability for the inhalation toxicity evaluation of other natural mineral fibers of concern.

Background: Asbestos has been classified as a human carcinogen, and exposure may increase the risk of diseases associated with impaired respiratory function. As the range of health effects and airborne concentrations that result in health effects across asbestos-related natural mineral fiber types are not fully understood, the National Institute of Environmental Health Sciences has established a series of research studies to characterize hazards of natural mineral fibers after inhalation exposure. This paper presents the method development work of this research project., Results: A prototype nose-only exposure system was fabricated to explore the feasibility of generating natural mineral fiber aerosol for in vivo inhalation toxicity studies. The prototype system consisted of a slide bar aerosol generator, a distribution/delivery system and an exposure carousel. Characterization tests conducted using Libby Amphibole 2007 (LA 2007) demonstrated the prototype system delivered stable and controllable aerosol concentration to the exposure carousel. Transmission electron microscopy (TEM) analysis of aerosol samples collected at the exposure port showed the average fiber length and width were comparable to the bulk LA 2007. TEM coupled with energy dispersive spectrometry (EDS) and selected area electron diffraction (SAED) analysis further confirmed fibers from the aerosol samples were consistent with the bulk LA 2007 chemically and physically., Conclusions: Characterization of the prototype system demonstrated feasibility of generating LA 2007 fiber aerosols appropriate for in vivo inhalation toxicity studies. The methods developed in this study are suitable to apply to a multiple-carousel exposure system for a rat inhalation toxicity testing using LA 2007.

Objective: We developed predictive formulae for the in vitro dissolution rate constant k dis of acid-soluble synthetic vitreous fibers (SVF), paralleling our earlier work with glass wools, which are typically more soluble at neutral pH. Developing simple models for predicting the k dis of a fiber can allow prediction of in vivo behavior, aid fiber developers, and potentially reduce in vivo testing., Methods: The k dis of several acid-soluble SVF were determined using high simulant fluid flow/fiber surface area (F/A) conditions via a single-fiber measurement system. Four fluids were employed, varying in base composition and citrate levels. Equations predicting the k dis were derived from fiber chemistry and dissolution measurements for two of the fluids., Results: Testing of several fibers showed a ∼10× increase in the k dis when citrate was included in the simulant solution. Data from tests with Stefaniak's citrate-free Phagoloysosmal Simulant Fluid (PSF) yielded k dis values aligned with expectations from in vivo results, unlike results from citrate-containing modified Gamble's solution. Predictive equations relating fiber chemistry to k dis showed reasonable agreement between the measured and predicted values., Conclusions: Citrate inclusion in the solution under high F/A conditions significantly increased the measured k dis . This resulted in more biorelevant data being obtained using the PSF fluid with the high F/A method used. The developed predictive equations, sufficient for fiber development work, require refinement before a recommending their use in place of in vivo biopersistence testing. Significant fit improvements are possible through additional measurements under these experimental conditions.

Objectives The aim of Evalutil is to document occupational exposure to asbestos and man-made mineral fibers. Methods These databases provide grouped descriptive and metrological data from observed situations of occupational exposure, collected through the analysis of scientific articles and technical reports by industrial hygienists. Results Over 5,000 measurements were collected. We describe the occupations, economic activities, fiber-containing products, and operations on them that have been documented most often. Graphical measurement syntheses of these data show that the situations presented for asbestos and RCF, except mineral wools, report fiber concentrations mainly above historical occupational exposure limits. Conclusion Free access to these data in French and in English on the Internet () helps public health and prevention professionals to identify and characterize occupational exposures to fibers. Extended recently to nanoscale particles, Evalutil continues to contribute to the improvement of knowledge about exposure to inhaled particles and the health risks associated with them. Am. J. Ind. Med. 58:1059-1074, 2015. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]