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There are six elongate mineral particles (EMPs) corresponding to specific dimensional and morphological criteria, known as asbestos. Responsible for health issues including asbestosis, and malignant mesothelioma, asbestos has been well researched. Despite this, significant exposure continues to occur throughout the world, potentially affecting 125 million people in the workplace and causing thousands of deaths annually from exposure in homes. However, there are other EMPS, such as fibrous/asbestiform erionite, that are classified as carcinogens and have been linked to cancers in areas where it has been incorporated into local building materials or released into the environment through earthmoving activities. Erionite is a more potent carcinogen than asbestos but as it is seldom used for commercial purposes, exposure pathways have been less well studied. Despite the apparent similarities between asbestos and fibrous erionite, their health risks and exposure pathways are quite different. This article examines the hazards presented by EMPs with a particular focus on fibrous erionite. It includes a discussion of the global locations of erionite and similar hazardous minerals, a comparison of the multiple exposure pathways for asbestos and fibrous erionite, a brief discussion of the confusing nomenclature associated with EMPs, and considerations of increasing global mesothelioma cases.

Erionite is a fibrous zeolite classified as a Group 1 carcinogen and may pose a significant public health hazard when aerosolized into individual respirable-sized fibers. SEM-EDXA has been widely used to identify individual erionite fibers in environmental samples as it combines morphological imaging with elemental analysis. However, the reliability of SEM-EDXA data when applied to the quantitative chemical analysis of individual erionite fibers rather than bulk samples remains uncertain. This study analyzed 325 individual erionite fibers (obtained from a bulk sample with high-purity) across a range of fiber widths and four commonly used sample preparation methods, using two different SEM-EDS systems. SEM-EDXA results were compared with previously acquired EPMA reference data from the bulk sample to assess analytical accuracy. Systematic overestimations of Si and Mg and underestimations of Al, K, and Ca were observed. Framework elements (Si and Al) exhibited relatively stable detection in fibers > 0.5 μm. However, preparation methods—deionized water dispersion and hydrogen peroxide digestion—introduced greater variability, likely due to ion exchange and cation mobilization. Despite the purity of the erionite bulk sample, none of the analyzed individual fibers fully met the established quantitative chemical criteria for erionite identification. These results highlight the need for pre-calibration with erionite standards and the application of correction index to improve SEM-EDX accuracy, and subsequent confirmation of mineralogy using TEM-SAED, when determining whether individual fibers found in airborne samples are erionite.

Synthesis of zeolite T with a variety of desired characteristics necessitates extensive work in formulation and practical experiments, either by conventional hydrothermal methods or aided with different approaches and synthesis techniques, such as secondary growth or microwave irradiation. The objectives of this review are to adduce the potential work in zeolite T (Offretite-Erionite) synthesis, evaluating determining factors affecting the synthesis and quality of zeolite T crystals. Attention is given to extensive studies that interconnect with other significant findings.

Fibrous erionite is classified by the International Agency for Research on Cancer (IARC) as carcinogenic substance to humans (Group 1). In the areas where it is present in the bedrock, it may cause environmental exposure, and both professional and environmental exposures are possible when the bedrock is used for industrial applications (e.g., building materials). For health and environment protection, prevention is a priority action. In this framework, the recent guidelines of the Consensus Report of the Weinman International Conference on Mesothelioma suggest identifying locations where potentially hazardous mineral fibers (like erionite) are found in the environment, to prevent environmental exposure. The present study will show that one such potentially hazardous mineral fiber might be fibrous ferrierite. Here, the mineralogy, chemical-physical properties, and surface activity of a hydrothermal fibrous ferrierite from Monte Lake British Columbia (Canada) and a diagenetic fibrous ferrierite from Lovelock, Nevada (U.S.A.), were investigated using a combination of \"state of the art\" experimental methods including optical microscopy, electron microscopy and microprobe analysis, laser ablation-inductively coupled plasma-mass spectrometry (for the trace elements), vibrational spectroscopy, electron paramagnetic resonance, and synchrotron powder diffraction. The chemical-physical properties of these fibrous ferrierites (morphometric parameters, specific surface area, chemical composition with special attention to metals, mainly iron) that prompted adverse effects in vivo were compared to those of the positive carcinogenic standard fibrous erionite-Na from Jersey, Nevada (U.S.A.). The results of our study have demonstrated that, although there are differences in the crystal chemistry and genetic environment, ferrierite samples exhibit outstanding similarities with fibrous erionite samples: both fibrous erionite and fibrous ferrierite may occur in large amounts as microcrystalline fibrous-asbestiform phases in diagenetic rocks with fibers of breathable sizes. For both zeolites, iron is not structural but is associated with impurities lying at the surface of the fibers. Moreover, data useful to understand the surface activity of these fibrous ferrierites were collected. As far as hydrothermal sample is concerned, the EPR data indicate the presence of hydrophilic (SiO-, AlO-, SiOH) and hydrophobic (Si-O-Si) interacting surface groups able to bind the charged CAT1 probes at close sites and attract the probes in the water pools formed into the fiber aggregates. A high percentage of CAT1 probes weakly interacting with the surface due to competition with metal ions were observed for surface of the diagenetic sample. CAT8 probes were less adsorbed by its surface if compared to the diagenetic sample but the more charged surface provided a stronger binding strength for the diagenetic sample compared to the hydrothermal one. In summary, the results of this study indicate that fibrous ferrierite may represent a potential health hazard and, applying the precautionary principle, it should undergo a procedure of toxicity testing.

Erionite is a non-asbestos fibrous zeolite classified by the International Agency for Research on Cancer (IARC) as a Group 1 carcinogen and is considered today similar to or even more carcinogenic than the six regulated asbestos minerals. Exposure to fibrous erionite has been unequivocally linked to cases of malignant mesothelioma (MM) and this killer fibre is assumed to be directly responsible for more than 50% of all deaths in the population of the villages of Karain and Tuzköy in central Anatolia (Turkey). Erionite usually occurs in bundles of thin fibres and very rarely as single acicular or needle-like fibres. For this reason, a crystal structure of this fibre has not been attempted to date although an accurate characterization of its crystal structure is of paramount importance for our understanding of the toxicity and carcinogenicity. In this work, we report on a combined approach of microscopic (SEM, TEM, electron diffraction), spectroscopic (micro-Raman) and chemical techniques with synchrotron nano-single-crystal diffraction that allowed us to obtain the first reliable ab initio crystal structure of this killer zeolite. The refined structure showed regular T —O distances (in the range 1.61–1.65 Å) and extra-framework content in line with the chemical formula (K 2.63 Ca 1 . 57 Mg 0.76 Na 0.13 Ba 0.01 )[Si 28.62 Al 7.35 ]O 72 ·28.3H 2 O. The synchrotron nano-diffraction data combined with three-dimensional electron diffraction (3DED) allowed us to unequivocally rule out the presence of offretite. These results are of paramount importance for understanding the mechanisms by which erionite induces toxic damage and for confirming the physical similarities with asbestos fibres.

The zeolitic rocks of Akrotiri, on Santorini Island (Aegean Sea, Greece), can be grouped according to the zeolite minerals present. The first group includes zeolitic rocks that contain only clinoptilolite, the second group contains clinoptilolite and mordenite and the third group contains only mordenite. Clinoptilolite accounts for up to 56 wt.% and mordenite for up to 69 wt.% of the rocks. All samples contain feldspars (8-36 wt.%), clay minerals (6-8 wt.%), quartz (3-6 wt.%), opal-CT (2 wt.%), amphibole (2-4 wt.%) and amorphous materials (4-7 wt.%). The studied samples were classified chemically as andesites or dacites. The ammonium-exchange capacity of the studied samples was 104-158 meq 100 g-1. According to Commission Implementing Regulation (EU) No. 651/2013, zeolitic rocks that contain ≥80 wt.% clinoptilolite, ≤20 wt.% clay minerals and are free of fibrous minerals and quartz can be used as feed additives in animal husbandry. Zeolites with fibrous habit (mordenite, erionite, secondarily roggianite and mazzite) and SiO2 minerals such as quartz, cristobalite and tridymite can be dangerous to both humans and animals. The mineralogical study showed that, due to their low clinoptilolite content and the presence of both quartz and fibrous mordenite, the studied zeolitic rocks do not conform with European Regulation No. 651/2013. As a result, their use as feed additives and nutrition supplements is prohibited.

The modification of natural zeolites via ion exchange is an efficient technique used to improve their performances and tune their properties for specific applications. In this study, a natural levyne-Ca intergrown with erionite was fully exchanged by Ag and its structure [with idealized chemical composition Ag (Si,Al) ·18H O] was investigated by combining a theoretical and experimental approach. Single-crystal X-ray difraction data demonstrated that Ag-levyne maintained the space group, characteristic of the natural levyne. Ag ions distribute over partially occupied sites along the threefold axis and, differently from the pristine material, at the wall of the 8-membered ring window of the cavity. The lack of ~30% of Ag ions that could not be located by the structural refinement is ascribed to the strong disorder of the extraframework occupants. The structural results obtained by Molecular Dynamics simulations are in overall agreement with the experimental data and showed that, on average, Ag is surrounded by ~2 H O and 1 framework oxygen at distances between 2.43 and 2.6 Å. Molecular Dynamics trajectories indicate that the occurrence of silver inside the D6R cage depends on the water content: silver occupancy of D6R cages is estimated to be 83, 30, and 0% when the structure contains 3, 2.5, and 2 H O per Ag ion, respectively. The cation-exchange process, as demonstrated by scanning electron microscopy and energy-dispersive spectroscopy (SEM-EDS) spectrometry, affects the intergrown erionite as well. A structural characterization of the Ag-erionite phase (with dimension <100 μm) was possible by means of a Cu α micro-focus source: structure solution pointed to space group, indicating no change with respect to natural erionite. In agreement with previous studies, K ions in the cancrinite cage could not be exchanged, whereas Ag is found in the cavity.

Microporous erionite-activated carbon (E-AC) composite was synthesized by activating oil palm ash followed by reacting with aluminum oxide (Al 2 O 3 ) under alkaline conditions using hydrothermal method. The Al 2 O 3 was added to the activated palm ash to balance the excess silica dioxide (SiO 2 ) to obtain the erionite type of zeolite. The E-AC composite was employed to remove a potent pharmaceutical water pollutant, doxycycline antibiotic under batch adsorption. The effect of solution pH (3–13), doxycycline initial concentration, and temperature were screened in the batch study. The E-AC composite revealed appreciable surface area and average pore size of 467.23 m 2 /g and 2.765 nm, respectively, with abundant chemical surface hydroxyl (-OH) and amine (N-H) adsorptive sites. The textural and surface chemistry greatly contributed to a high monolayer adsorption capacity of 353.81 mg/g at 50 °C. Also, the Langmuir isotherm with a high R 2 of 0.99 for doxycycline adsorption on E-AC sufficiently described the equilibrium data. High monolayer adsorption capacity of E-AC compared to other adsorbents in the literature suggests the efficiency of this study. Novel composite synthesis was aimed to enhance the surface area and to increase the doxycycline removal capacity. These encouraging results show that the E-AC composite could pave the way for more low-cost composites to be used as adsorbents for pharmaceutical and other pollutant removals from wastewater.

Particulate matters (PM) are atmospheric aerosols that can derive from anthropogenic and natural sources, directly affecting air quality. Particularly, fine grain-sized particulate matters (PM10, PM2.5, and ultrafine PM-UFPM) can be carried by winds. Such mineral dust can cause significant respiratory diseases. Furthermore, the alteration of the volcanic glass causes the crystallization of abundant erionite minerals in the Cappadocian rhyolitic ignimbrites. Malignant mesothelioma cases have been known for many years in the Cappadocia region, and exposure to acicular–fibrous erionite minerals in the natural stones of which village houses are built is shown as the primary cause (Indoor effect). The state constructed new buildings to prevent indoor exposure of the villagers since more than 50% of the inhabitants of some villages had lung cancer due to indoor exposure. Then the villages such as Tuzköy and Karain were moved to their new places. This study emphasizes mineralogically hazardous substances such as amorphous and crystalline silica and the cancerogenic erionite minerals based on scanning electron microscopy and XRD works. The geological units containing these minerals are open to wind erosion, as demonstrated by the Böhme abrasion resistance tests. Besides, we show that the relocation of villages probably has a limited effect in solving the problem. In addition, our HYSPLIT particle transport models determining the possible impact areas show that the issue of outdoor exposure has also become critical. With the dispersion of harmful substances into the atmosphere, humans are subject to short- and long-term exposures to those toxic substances.

Trace quantities of erionite series minerals were identified along with chabazite, clinoptilolite, and morderite within Chichindaro rhyolites (~ 30 Ma) at latitude 21°8′30″–21°17′00″ and longitude 101°5′00″–101°10′00″, ~ 15 km south of the present-day town of San Felipe in the state of Guanajuato, Mexico. Special attention was given to the erionite -K, Na, and Ca varieties. Despite their occurrence in trace amounts, image analyses of these minerals with the aid of Scanning Electron Microscope indicates the existence of both hair-like and needle-like fibers that are 5.85–29.26 μm long and 2.510–0.252 μm thick, which allows them to be categorized as “inhalable” (with length > 5 μm and thickness < 3 μm) that readily enters the respiratory tract of human and their livestock residing in this region. Chemical data along with the atomic% and apfu values obtained based on 72 oxygen atoms reveals that six crystals spots from SF-14-a and sample SF-12 show Si/(Si + Al) = 0.69–0.78, similar to the cancerogenic erionite identified at Tierra Blanca, Mexico; Lessini Mountains, NE Italy; Cappadocia, Turkey, and North Dakota, USA. However, these spots fail the E% and Mg content test. On the contrary, spots SF-14-2A, 2B, and 2C show Mg content in the range of 0.35–0.54 and balance error E% of − 2.90% (only in SF-14-2B) and pass the positive identification tests for erionites. Therefore, it is advisable to comment that the erionite series minerals identified within Chichindaro rhyolites area are of “undifferentiated” type and may not be carcinogenic.