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Mineralogical study of the fibrous zeolites erionite and offretite and hazard assessment
Full text linkThe exposure of erionite fibres to humans has been unambiguously linked to malignant mesothelio-ma, and in vivo studies have demonstrated that, at present, erionite is the most carcinogenic mineral in the world. Recently, a growing concern has developed regarding the potential risks associated with environmental and occupational exposures to erionite in different Countries, such as Turkey, U.S.A., Mexico and Iran. Despite of the great number of researches, the relationships among miner-alogical features and biological activity of erionite have not been fully understood and there are no systematic studies on the distribution of erionite or other similar fibrous zeolites in the environment. Moreover, there is another zeolite, named offretite, which is closely related both structurally and chemically to erionite. Despite commonly occurring as prisms, offretite has also been found under asbestiform habit, meaning that the morphology of its crystals has not yet been fully known and many mineralogical aspects are still to be discovered. Due to these similarities and to the possible in-tergrowth, the distinction between erionite and offretite can be hampered. To date, there are no studies regarding a potentially hazard of offretite fibers and it is unclear whether the mineralogical distinction between erionite and offretite has any health implications. The gap of knowledge of the fibrous zeolites erionite and offretite has been the starting point for the development of the present PhD project.
A multi-methodological approach, based on field investigation, morphological characterization, SEM/EDS chemical analysis and structure refinement through X-ray powder diffraction was ap-plied to different samples of potentially carcinogenic erionite and offretite from Italy. These investi-gations were performed on representative samples with variable morphologies, ranging from pris-matic, through acicular and fibrous, to extremely fibrous asbestiform habits. In the investigated samples, fibrils of inhalable size are present. Considering that the toxicity and the carcinogenic po-tential of erionite are associated with its size parameters, together with its in vivo durability and very high surface area, most of the investigated fibers may also be potentially carcinogenic. Despite of the lack of epidemiological information on populations exposed to natural asbestiform minerals oth-er than asbestos and erionite, results acquired in the present investigation suggest that other mineral fibres of similar size, habit, and biopersistence may carry a risk for humans.
Successively, morpho-chemical characterization and surface properties determinations were per-formed on a selection of different asbestiform zeolite fibers: two erionite samples (from USA and Turkey), one offretite sample (Italy) and, for comparison, one scolecite sample (India). These sam-ples have been used to carry out in-vitro experiments to assess the level of reactivity and transfor-mation that such fibers may induce to micelles and membranes in contact with them, and therefore, indirectly the possibility of leading to asbestos-related lung diseases. With this aim, specific surface area determinations coupled with EPR analysis and TEM images in the presence of model mem-branes are performed. This type of study has allowed me to obtain informations on the fiber inter-nalization in the membranes and the interactions occurring at a molecular level that mimicked the at-tack of the fibers at the cell membrane. The carcinogenicity of the zeolites may be nicely related to the structural modifications of the model membranes when interacting with these zeolite fibers. These results helped to clarify the chemical properties and the surface interacting ability of these ze-olite fibres which may be related to their carcinogenicity
Stepwise dehydration of thomsonite (THO) with disordered Si/Al distribution: A new partially hydrated phase
Full text linkThe structural transformations occurring as a function of increasing temperature in zeolites are of interest because the porous structure, and therefore the physical properties, can significantly change.
Zeolites with THO framework type are small-pore materials, which received attention because of their applications in catalytic processes. The majority of THO zeolites (synthetic and natural) are characterized by an ordered distribution of the cations at the tetrahedral sites. To date, few cases of disordered thomsonite have been reported. In this study, we investigated the dehydration behavior of a natural thomsonite with disordered Si/Al distribution and chemical composition Ca3.34Na2.66Si11Al9O40∙12H2O. The structure was determined from room temperature (RT) to 698 K in order to compare the thermal behavior with that reported for the ordered variety. Accurate structural analysis was performed by in situ single crystal X-ray diffraction. The dehydration starts at 348 K. Up to 498 K, thomsonite gradually releases four H2O. From 498 to 573 K, additional four H2O are lost and the space group changes from orthorhombic (Pbmn) to monoclinic (P21/n). This partially hydrated phase is characterized by a unit-cell volume contraction of -3% with respect to the RT phase and by a rearrangement of the extraframework cations in the zeolitic pores. The thermally treated thomsonite is able to reabsorb 50% of the lost H2O and transform to the orthorhombic phase, equivalent to that observed at lower temperatures. However, the diffraction pattern analysis indicated a high degree of mosaicity, most probably due to the residual stress accumulated during the phase transformation
Real-time observation of fibrous zeolites reactivity in contact with simulated lung fluids (SLFs) obtained by Atomic Force Microscope (AFM)
Full text linkEnvironmental exposure of erionite fibres to humans has been linked to malignant mesothelioma and at present is classified as the most carcinogenic mineral. In opposite, there are no studies regarding a potential hazard of offretite fibres, closely related to erionite both structurally and chemically. In this paper, the interactions of erionite and offretite surfaces with SLFs were investigated by means of in situ AFM. To simulate different environments in the lungs, Artificial Lysosomal Fluid (ALF) and Gamble’s solution were used. In ALF (4.15 < pH < 4.31) the dissolution of erionite and offretite surfaces was detected, as well as an evident removal of particles (mainly attributed to impurities) from the crystal faces. Instead, the growing of a layer of an unknown phase on the surface of both zeolites, was observed during the interaction with Gamble’s solution (7.4 < pH < 8.48). The thickness of this layer reached few tens on nanometers and covered all the observed areas. The understanding of the observed processes is of paramount importance, since they could be potentially involved in the mechanisms triggering the toxicological effects of erionite fibres
Humidity- and temperature-dependent study of YUG type zeolite. A new dehydrated topology
No full textChrysotile within calcite veins from Northern Apennines
Full text linkIn the Northern Apennines several olistoliths made up of serpentinites, calpionelle limestones and ophiolitic breccias
have been recognized within the Porcellara Complex, Monte Cassio Unit. These olistoliths are frequently crossed by a
dense network of centimeter to decimeter veins generally filled by carbonate minerals (e.g. La Costa, Berceto, PR).
Morphological and compositional data (SEM-EDS and XRPD) have revealed that these carbonate minerals consist
mainly of well-formed, white to milky calcite crystals, strictly associated with chrysotile. This mineral is found as white
thin fibers (< 1 micron), grew up in intimate association with calcite crystals. These fibers may be very rare and
randomly scattered within the crystals of calcite, or can be grouped into bundles of millimeter to centimeter size. At
times, the chrysotile can get to completely fill the vein. Chrysotile fibers are well-formed and euhedral at all scales from
hand specimen to electron microscope images. In some cases, individual fibers of chrysotile are not visible in hand
specimen or under the petrographic microscope; however, SEM images show the characteristic elongate crystal
morphology. The fibers are also characteristically curved at the millimeter scale.
It is important to note that the fibers of chrysotile appear, frequently, as a physical extension of calcite crystals, without
any evident morphological discontinuity in the transition from a massive (calcite) to a fibrous (chrysotile) appearence.
The results of detailed SEM-EDS elemental analyses carried out in various segments of the contact areas between
calcite and chrysotile crystals seem to show a gradual transition in chemical composition from pure calcite to pure
chrysotile phases, passing through various intermediate arrangements
Potential carcinogenic erionite from Lessini Mounts, NE Italy: Mineralogical and chemical characterization
No full textExposure of humans to erionite fibers of suitable morphology and dimension has been unambiguously
linked to the occurrence of malignant mesothelioma. For this reason, a morphological,
morphometrical, mineralogical, and chemical investigation was performed on two representative
samples of potential carcinogenic, fibrous erionite from Lessini Mounts, northeastern (NE) Italy,
which has not apparently been examined previously. The first sample is erionite-Ca with an
extremely fibrous, hair-like and flexible appearance, and growth in intimate association with
levyne. The second sample is erionite-Ca with prismatic to acicular crystals and rigid behavior,
enriched in K+ and Ca2+ extra-framework cations. Although erionite is a nominally Fe-free phase,
iron (Fe) was detected in low amounts in all the analyzed crystals. In both the investigated
samples, erionite is present as individual fibers of respirable size. Considering that the toxicity
and carcinogenic potential of erionite is associated with its size parameters, together with its in
vivo durability and high surface area, most of the investigated fibers may also be potentially
carcinogenic. The presence of erionite in extensively quarried and largely employed volcanic
rocks, suggesting the need for detailed health-based studies in the region
Historical and clinical considerations on Ekbom's syndrome
No full textEkbom's syndrome represents a relatively uncommon neuropsychiatric condition characterized by the recurrent and bizarre fixed delusional belief to be infested by small organisms or even unanimated materials ('Morgellons disease'), without any objective evidence of infestation/parasitosis. The condition, mainly diagnosed in a nonpsychiatric setting, is supposed to be largely underestimated and, hence, undermanaged. The present comprehensive review aims at investigating Ekbom's syndrome, from a historical, epidemiological, clinical and therapeutic perspective, by providing diagnostic-treatment strategies in managing this condition in routine psychiatric clinical settings. The prototypical patient is a middle-aged woman (or a younger subject in those cases in which substance and/or alcohol abuse is implicated), often single, divorced or widowed (loneliness component and social withdrawal), who has already consulted several specialists due to skin lesions associated with a firm and delusional belief to be infested. The identification and diagnosis are challenging due to poor patient's insight, poor knowledge and collaboration between specialists and differential diagnoses to be considered before asking for a psychiatric referral. Management and treatment strategies mainly derive from isolated case reports or observational studies with a small sample size. Further randomized clinical trials should be performed to evaluate the efficacy of newer antipsychotic drugs, including long-acting injectable formulations
Metasomatic to Hydrothermal Genesis of Natural Calcium Silicate Hydrates (C-S-H): Evidence from Lessini Mountains, Veneto Volcanic Province, Italy
Full text linkWe report the occurrence of natural calcium silicate hydrates (C-S-H) from the Grolla quarry in the Lessini Mountains of Northern Italy. These minerals are formed by basic and ultrabasic magma interacting with carbonate rocks. The mineral assemblage includes thaumasite, xonotlite, tobermorite, and plombierite, often intergrown with other silicates, as well as minor amounts of carbonates and sulfates. Common zeolites in this area include chabazite, phillipsite/harmotome, natrolite, and thomsonite. Although less abundant, these zeolites are typically associated with calcite, fluoroapophyllite, and barite. The Grolla quarry outcrop allows for the study of the in situ complex crystalline overgrowths and specific crystal chemistry of rare natural mineral phases, such as C-S-H minerals, formed under metasomatic to hydrothermal conditions
Morphology and chemistry of erionite and offretite: increasing data of carcinogenic fibrous zeolites
No full textZeolites belonging to erionite and offretite families were recently discovered to be very dangerous for the human
health since demonstrated to be carcinogenic (e.g. Carbone et al., 2007; Dogan et al., 2008). Notwithstanding this, the
morphologies of erionite and offretite fibers have not yet been fully understood and many mineralogical and
toxicological aspects are still unknown. Moreover, it is unclear whether the mineralogical similarity between erionite
and offretite has any health implications. For these reasons, it is of paramount importance to improve the knowledge of
their physical and chemical properties because they may be related to the carcinogenic potential of these fibrous
zeolites.
Identification of (and distinction between) erionite and offretite can be difficult because of (i) their mineralogical
similarities and (ii) the possibility of intergrowth of the two species within each crystal (Passaglia et al., 1998). Here we
present morphological and chemical data of erionite and offretite samples, collected from various localities. Four main
morphological types of crystals have been observed. (I) Elongated prisms, often grouped in sub-spherical forms, with a
strong tendency to develop thin fibers. (II) Very elongated, fibrous prisms, terminated by a wider, massive form with
pseudo-hexagonal section. (III) Stocky prismatic forms, with a strong tendency to generate fibers at the ends of the
crystals. (IV) Extremely fibrous crystals with "soft" appearance, which can be found both as single-phases and in
epitaxial growth with other minerals.
Chemical data indicate the presence of a wide range of compositions, based on extra-framework dominant cation.
Types I and III can be referred to both offretite and erionite compositions; this latter has been found as K-, Na- and Caerionite.
Type II shows a notably chemical variation: the prismatic, fibrous body corresponds to Na-erionite, while the
wider, massive termination is offretite. Type IV is always erionite (both K- and Ca-members) and no offretite samples
have been found with this extremely fibrous habit. Intermediate chemical compositions could be natural or due to
intimate intergrowths of these two minerals. A better understanding of the potential toxicity is needed across the range
of erionite and offretite compositions
POTENTIALLY CARCINOGENIC ERIONITE IN ITALY: GEOLOGICAL OCCURRENCE AND RISK ASSESSMENT
No full textErionite is a fibrous mineral of the zeolite group mainly occurring as hydrothermal alteration product. The
exposure of humans to erionite fibres has been unambiguously linked to malignant mesothelioma cases
(Baris et al., 1978), and in vivo studies have demonstrated that erionite is significantly more tumorigenic than
asbestos (Coffin et al., 1992). Recently, a growing concern has developed regarding the potential risks for
environmental and occupational exposures to erionite in Turkey (Carbone et al., 2011), in the United States
(Saini-Eidukat & Triplett, 2014), in Mexico (Ortega-Guerrero & Carrasco-Nùñez, 2014) and possibly in Iran
(Ilgren et al., 2015). Newly researches on the identification of segregation of Fe(II) provide very important
information for the understanding of the molecular mechanism/s inducing its strong carcinogenicity (Ballirano
et al., 2015). Notwithstanding this, the relationships among mineralogical features and biological activity of
erionite have not yet been fully understood and there are no systematic studies on the distribution of erionite
or other similar fibrous zeolites in the environment.
In Italy, erionite was reported in Sardinia and Veneto (Passaglia & Galli, 1974; Mattioli et al., 2016).
Nevertheless, a systematic mapping of its distribution, the quantification of its presence in rocks and data
about airborne fibers are still missing. Here we present mineralogical data of new erionite occurrences from
Northern Italy, with a state of the art on the occurrence of erionite in Italy and some other potentially erionitebearing
deposits. The studied erionite samples show prismatic to extremely fibrous habits and a variable
tendency to break down in thin fibrils, which could be potentially pathogenic on inhalation. The chemical data
acquired revealed variable amounts of Ca, Na, K and Mg as extra-framework cations, with small amounts of
Fe.
In Italy the knowledge of the epidemiology of mesothelioma linked to erionite is extremely scarce, and
domestic cases from exposure to airborne erionite fibers are still to be inferred. Identifying the areas in Italy
where erionite occurs naturally is a starting point for further specific studies on epidemiology, public health
and natural hazards. An effective risk assessment in Italy will require coordinated actions from government
agencies, local health authorities, Universities and research centers, in order to record the actual presence
of fibrous zeolites, recognizing mineral species and quantifying their abundance in rock deposits
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