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Raneri S, Gianoncelli A, Bonanni V, Mirata S, Scarfì S, Fornasini L, Bersani D, Baroni D, Picco C, Gualtieri AF. The influence of cation exchange on the possible mechanism of erionite toxicity: A synchrotron-based micro-X-ray fluorescence study on THP-1-derived macrophages exposed to erionite-Na. Environ Res 2024; 252:118878. [PMID: 38582417 DOI: 10.1016/j.envres.2024.118878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 04/02/2024] [Accepted: 04/03/2024] [Indexed: 04/08/2024]
Abstract
Fibrous erionite is the only zeolite classified as Group 1 carcinogen by the International Agency for Research on Cancer (IARC). Carcinogenesis induced by erionite is thought to involve several factors as biopersistence, the iron role and cation exchange processes. To better understand these mechanisms, a detailed investigation at the micro scale was performed, collecting elemental information on iron and cation release and their distribution in biological systems by synchrotron micro-X-ray fluorescence mapping (SR-micro-XRF) and synchrotron micro-X-ray absorption spectroscopy (SR-micro-XANES) at the TwinMic beamline (Elettra synchrotron) and at the ID21 beamline of the European Synchrotron Radiation Facility (ESRF). By microscopy and chemical mapping, highly detailed maps of the chemical and morphological interaction of biological systems with fibres could be produced. In detail, THP-1 cell line derived macrophages, used as in vitro model, were analysed during erionite-Na phagocytosis at different time intervals, after single dose exposure. For comparison, cellular fluorescent probes were also used to evaluate the intracellular free sodium and calcium concentrations. Synchrotron analyses visualised the spatial distribution of both fibre and mineral particle associated metals during the phagocytosis, describing the mechanism of internalisation of erionite-Na and its accessory mineral phases. The intracellular distribution of metals and other cations was mapped to evaluate metal release, speciation changes and/or cation exchange during phagocytosis. The fluorescent probes complemented microchemical data clarifying, and confirming, the cation distribution observed in the SR-micro-XRF maps. The significant cytoplasmic calcium decrease, and the concomitant sodium increase, after the fibre phagocytosis seemed due to activation of plasma membrane cations exchangers triggered by the internalisation while, surprisingly, the ion-exchange capacity of erionite-Na could play a minor role in the disruption of the two cations intracellular homeostasis. These results help to elucidate the role of cations in the toxicity of erionite-treated THP-1 macrophages and add knowledge to its carcinogenicity process.
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Affiliation(s)
- Simona Raneri
- CNR-ICCOM, National Research Council, Institute of Chemistry and OrganoMetallic Compounds, Via G. Moruzzi, 1, 56124, Pisa, Italy
| | - Alessandra Gianoncelli
- Elettra Sincrotrone Trieste, Strada Statale 14, Km 163.5 in Area Science Park, 34149 Basovizza Trieste, Italy
| | - Valentina Bonanni
- Elettra Sincrotrone Trieste, Strada Statale 14, Km 163.5 in Area Science Park, 34149 Basovizza Trieste, Italy
| | - Serena Mirata
- Department of Earth, Environment and Life Sciences, University of Genova, Corso Europa 26, 16132, Genova, Italy
| | - Sonia Scarfì
- Department of Earth, Environment and Life Sciences, University of Genova, Corso Europa 26, 16132, Genova, Italy.
| | - Laura Fornasini
- Department of Mathematical, Physical and Computer Sciences, University of Parma, Parco Area delle Scienze 7/A, 43124, Parma, Italy
| | - Danilo Bersani
- Department of Mathematical, Physical and Computer Sciences, University of Parma, Parco Area delle Scienze 7/A, 43124, Parma, Italy
| | - Debora Baroni
- Istituto di Biofisica, CNR, Via De Marini 6, 15149, Genova, Italy
| | - Cristiana Picco
- Istituto di Biofisica, CNR, Via De Marini 6, 15149, Genova, Italy
| | - Alessandro F Gualtieri
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Via G. Campi 103, 41125, Modena, Italy
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Gualtieri AF. Journey to the centre of the lung. The perspective of a mineralogist on the carcinogenic effects of mineral fibres in the lungs. J Hazard Mater 2023; 442:130077. [PMID: 36209608 DOI: 10.1016/j.jhazmat.2022.130077] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 09/23/2022] [Accepted: 09/26/2022] [Indexed: 06/16/2023]
Abstract
This work reviews the bio-chemical mechanisms leading to adverse effects produced when mineral fibres are inhaled and transported in the lungs from the perspective of a mineralogist. The behaviour of three known carcinogenic mineral fibres (crocidolite, chrysotile, and fibrous-asbestiform erionite) during their journey through the upper respiratory tract, the deep respiratory tract and the pleural cavity is discussed. These three fibres have been selected as they are the most socially and economically relevant mineral fibres representative of the classes of chain silicates (amphiboles), layer silicates (serpentine), and framework silicates (zeolites), respectively. Comparison of the behaviour of these fibres is made according to their specific crystal-chemical assemblages and properties. Known biological and subsequent pathologic effects which lead and contribute to carcinogenesis are critically reviewed under the mineralogical perspective and in relation to recent progress in this multidisciplinary field of research. Special attention is given to the understanding of the cause-effect relationships for lung cancer and malignant mesothelioma. Comparison with interstitial pulmonary fibrosis, or "asbestosis", will also be made here. This overview highlights open issues, data gaps, and conflicts in the literature for these topics, especially as regards relative potencies of the three mineral fibres under consideration for lung cancer and mesothelioma. Finally, an attempt is made to identify future research lines suitable for a general comprehensive model of the carcinogenicity of mineral fibres.
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Affiliation(s)
- Alessandro F Gualtieri
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Via G. Campi 103, Modena I-41125, Italy.
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Giordani M, Mattioli M, Cangiotti M, Fattori A, Ottaviani MF, Betti M, Ballirano P, Pacella A, Di Giuseppe D, Scognamiglio V, Hanuskova M, Gualtieri AF. Characterisation of potentially toxic natural fibrous zeolites by means of electron paramagnetic resonance spectroscopy and morphological-mineralogical studies. Chemosphere 2022; 291:133067. [PMID: 34838598 DOI: 10.1016/j.chemosphere.2021.133067] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 10/27/2021] [Accepted: 11/23/2021] [Indexed: 06/13/2023]
Abstract
This study explored the morphological, mineralogical, and physico-chemical features of carcinogenic erionite and other possibly hazardous zeolites, such as mesolite and thomsonite, while also investigating the interacting capability of the mineral surface at the liquid/solid interface. Extremely fibrous erionite is K+ and Ca2+-rich and shows the highest Si/Al ratio (3.38) and specific surface area (8.14 m2/g). Fibrous mesolite is Na+ and Ca2+-rich and displays both a lower Si/Al ratio (1.56) and a smaller specific surface area (1.56 m2/g). The thomsonite composition shows the lowest values of Si/Al ratio (1.23) and specific surface area (0.38 m2/g). Electron paramagnetic resonance data from selected spin probes reveal that erionite has a homogeneous site distribution and interacts well with all spin probes. The surfaces of mesolite and thomsonite are less homogeneous and closer polar sites were found through consequent interaction with the probes. The mesolite surface can also clearly interact but with a lower strength and may represent a potential health hazard for humans, though with a lower degree if compared to erionite. The thomsonite surface is not inert and interacts with the probes with a low-grade capability. We can expect small fragments of thomsonite to interact with the biological environment, though with a low-grade intensity.
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Affiliation(s)
- Matteo Giordani
- Department of Pure and Applied Sciences, University of Urbino Carlo Bo, 61029, Urbino, Italy
| | - Michele Mattioli
- Department of Pure and Applied Sciences, University of Urbino Carlo Bo, 61029, Urbino, Italy.
| | - Michela Cangiotti
- Department of Pure and Applied Sciences, University of Urbino Carlo Bo, 61029, Urbino, Italy
| | - Alberto Fattori
- Department of Pure and Applied Sciences, University of Urbino Carlo Bo, 61029, Urbino, Italy
| | | | - Michele Betti
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, 61029, Urbino, Italy
| | - Paolo Ballirano
- Department of Earth Sciences, Sapienza University of Rome, 00185, Rome, Italy
| | - Alessandro Pacella
- Department of Earth Sciences, Sapienza University of Rome, 00185, Rome, Italy
| | - Dario Di Giuseppe
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, I-41125, Modena, Italy
| | - Valentina Scognamiglio
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, I-41125, Modena, Italy
| | - Miriam Hanuskova
- Department of Engineering "Enzo Ferrari", University of Modena and Reggio Emilia, I-41125, Modena, Italy
| | - Alessandro F Gualtieri
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, I-41125, Modena, Italy
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Metintas S, Metintas M, Ak G, Hillerdal G, Koyi H. Mesothelioma in immigrants from Turkey: Genes have a minor role. Respir Med 2021; 186:106527. [PMID: 34218167 DOI: 10.1016/j.rmed.2021.106527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 05/28/2021] [Accepted: 06/27/2021] [Indexed: 11/21/2022]
Abstract
OBJECTIVE To examine the incidence and epidemiology of malignant mesothelioma in immigrants from Karain where there is an extraordinarily high incidence of mesothelioma, Cappadocia, Turkey, to Stockholm, Sweden, and their children over 20 years of age born in Stockholm, i.e. two genetically similar populations with and without erionite exposure. METHODS This survey was conducted as a retrospective cohort study. Standardized average annual mesothelioma incidence rates (AAMIRs) and mesothelioma standardized incidence ratio (mSIR) were calculated. Cox regression analysis was used to determine the importance of different factors related to mesothelioma risk. RESULTS The cohort consisted of 337 people, 203 of whom were born and/or lived in Karain before immigrating to Sweden (erionite-exposed), and 134 who were born in Stockholm (erionite-unexposed). There were 69 deaths, 42 (61%) due to mesothelioma, and two patients with the disease who were still alive. Of these 44 patients, 22 were men. All mesothelioma patients were in the erionite-exposed group. In the age group 30-49 years, mesothelioma developed in 11 of 38 (29%) with erionite exposure, while there were no cases among 86 persons in the non-exposed group. For men, the AAMIR was 253.9 per 100,000 persons in the whole cohort, and for women, it was 350.9. The mSIR was 71.9 for men and 393.1 for women. Exposure to erionite exceeding 20 years and age over 40 years were associated with increased mesothelioma risk. CONCLUSION Exposure to erionite is the leading cause of mesothelioma in Karain villagers, and genetic factors are probably of minor importance.
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Beaucham C, King B, Feldmann K, Harper M, Dozier A. Assessing occupational erionite and respirable crystalline silica exposure among outdoor workers in Wyoming, South Dakota, and Montana. J Occup Environ Hyg 2018; 15:455-465. [PMID: 29580185 DOI: 10.1080/15459624.2018.1447116] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Erionite is a naturally occurring fibrous mineral found in many parts of the world, including the western United States. Inhalational exposure to erionite fibers in some localities is associated with health effects similar to those caused by asbestos exposure, including malignant mesothelioma. Therefore, there is concern regarding occupational exposures in the western United States. Currently, there are no standard sampling and analytical methods for airborne erionite fibers, as well as no established occupational exposure limits. Due to the potential adverse health effects, characterizing and minimizing exposures is prudent. Crystalline silica also occurs naturally in areas where erionite is found, principally as the mineral quartz. Work activities involving rocks containing quartz and soils derived from those rocks can lead to exposure to respirable crystalline silica (RCS). The typically dry and dusty environment of the western United States can increase the likelihood of exposures to aerosolized rocks and soils, but inhalation exposure is also possible in more humid conditions. In this case study, we describe several outdoor occupational environments with potential exposures to erionite and RCS. We describe our method for evaluating those exposures and demonstrate: (1) the occurrence of occupational exposures to airborne erionite and RCS, (2) that the chemical make-up of the erionite mineral can be determined, and (3) that effective dust control practices are needed to reduce employee exposures to these minerals.
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Affiliation(s)
- Catherine Beaucham
- a National Institute for Occupational Safety and Health , Cincinnati , Ohio
| | - Bradley King
- b National Institute for Occupational Safety and Health , Denver , Colorado
| | - Karl Feldmann
- a National Institute for Occupational Safety and Health , Cincinnati , Ohio
| | - Martin Harper
- c Zefon International, Inc. , Ocala , Florida
- d Department of Environmental Engineering Sciences , University of Florida , Gainesville , Florida
| | - Alan Dozier
- a National Institute for Occupational Safety and Health , Cincinnati , Ohio
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Carbone M, Kanodia S, Chao A, Miller A, Wali A, Weissman D, Adjei A, Baumann F, Boffetta P, Buck B, de Perrot M, Dogan AU, Gavett S, Gualtieri A, Hassan R, Hesdorffer M, Hirsch FR, Larson D, Mao W, Masten S, Pass HI, Peto J, Pira E, Steele I, Tsao A, Woodard GA, Yang H, Malik S. Consensus Report of the 2015 Weinman International Conference on Mesothelioma. J Thorac Oncol 2017; 11:1246-1262. [PMID: 27453164 PMCID: PMC5551435 DOI: 10.1016/j.jtho.2016.04.028] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 03/31/2016] [Accepted: 04/26/2016] [Indexed: 01/31/2023]
Abstract
On November 9 and 10, 2015, the International Conference on Mesothelioma in Populations Exposed to Naturally Occurring Asbestiform Fibers was held at the University of Hawaii Cancer Center in Honolulu, Hawaii. The meeting was cosponsored by the International Association for the Study of Lung Cancer, and the agenda was designed with significant input from staff at the U.S. National Cancer Institute and National Institute of Environmental Health Sciences. A multidisciplinary group of participants presented updates reflecting a range of disciplinary perspectives, including mineralogy, geology, epidemiology, toxicology, biochemistry, molecular biology, genetics, public health, and clinical oncology. The group identified knowledge gaps that are barriers to preventing and treating malignant mesothelioma (MM) and the required next steps to address barriers. This manuscript reports the group’s efforts and focus on strategies to limit risk to the population and reduce the incidence of MM. Four main topics were explored: genetic risk, environmental exposure, biomarkers, and clinical interventions. Genetics plays a critical role in MM when the disease occurs in carriers of germline BRCA1 associated protein 1 mutations. Moreover, it appears likely that, in addition to BRCA1 associated protein 1, other yet unknown genetic variants may also influence the individual risk for development of MM, especially after exposure to asbestos and related mineral fibers. MM is an almost entirely preventable malignancy as it is most often caused by exposure to commercial asbestos or mineral fibers with asbestos-like health effects, such as erionite. In the past in North America and in Europe, the most prominent source of exposure was related to occupation. Present regulations have reduced occupational exposure in these countries; however, some people continue to be exposed to previously installed asbestos in older construction and other settings. Moreover, an increasing number of people are being exposed in rural areas that contain noncommercial asbestos, erionite, and other mineral fibers in soil or rock (termed naturally occurring asbestos [NOA]) and are being developed. Public health authorities, scientists, residents, and other affected groups must work together in the areas where exposure to asbestos, including NOA, has been documented in the environment to mitigate or reduce this exposure. Although a blood biomarker validated to be effective for use in screening and identifying MM at an early stage in asbestos/ NOA-exposed populations is not currently available, novel biomarkers presented at the meeting, such as high mobility group box 1 and fibulin-3, are promising. There was general agreement that current treatment for MM, which is based on surgery and standard chemotherapy, has a modest effect on the overall survival (OS), which remains dismal. Additionally, although much needed novel therapeutic approaches for MM are being developed and explored in clinical trials, there is a critical need to invest in prevention research, in which there is a great opportunity to reduce the incidence and mortality from MM.
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Affiliation(s)
- Michele Carbone
- Thoracic Oncology, University of Hawaii Cancer Center, Honolulu, Hawaii.
| | - Shreya Kanodia
- Thoracic Oncology, University of Hawaii Cancer Center, Honolulu, Hawaii; Samuel Oschin Comprehensive Cancer Institute and Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, California
| | - Ann Chao
- Center for Global Health, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Aubrey Miller
- National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina
| | - Anil Wali
- Center to Reduce Cancer Health Disparities, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - David Weissman
- Respiratory Health Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia
| | | | | | - Paolo Boffetta
- Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Brenda Buck
- Department of Geoscience, University of Nevada Las Vegas, Las Vegas, Nevada
| | - Marc de Perrot
- Princess Margaret Cancer Centre, University Health Network, Toronto, Canada
| | - A Umran Dogan
- Chemical and Biochemical Engineering Department and Center for Global and Regional Environmental Research, University of Iowa, Iowa City, Iowa
| | - Steve Gavett
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina
| | | | - Raffit Hassan
- Thoracic Oncology Branch, Center for Cancer Research, National Institutes of Health, Bethesda, Maryland
| | - Mary Hesdorffer
- Mesothelioma Applied Research Foundation, Alexandria, Virginia
| | - Fred R Hirsch
- University of Colorado Cancer Center, Denver, Colorado
| | - David Larson
- Thoracic Oncology, University of Hawaii Cancer Center, Honolulu, Hawaii
| | - Weimin Mao
- Cancer Research Institute, Zhejiang Cancer Hospital and Key Laboratory of Diagnosis and Treatment Technology on Thoracic Oncology of Zhejiang, Hangzhou, People's Republic of China
| | - Scott Masten
- National Toxicology Program, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina
| | - Harvey I Pass
- Cardiothoracic Surgery, New York University Langone Medical Center, New York, New York
| | - Julian Peto
- Cancer Research UK, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Enrico Pira
- Department of Public Health and Pediatrics, University of Turin, Turin, Italy
| | - Ian Steele
- Notre Dame Integrated Imaging Facility, Notre Dame University, Notre Dame, Indiana
| | - Anne Tsao
- Department of Thoracic and Head and Neck Medical Oncology, Division of Cancer Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas
| | - Gavitt Alida Woodard
- Thoracic Surgery, University of California at San Francisco, San Francisco, California
| | - Haining Yang
- Thoracic Oncology, University of Hawaii Cancer Center, Honolulu, Hawaii
| | - Shakun Malik
- Cancer Therapy Evaluation Program, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
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Zebedeo CN, Davis C, Peña C, Ng KW, Pfau JC. Erionite induces production of autoantibodies and IL-17 in C57BL/6 mice. Toxicol Appl Pharmacol 2014; 275:257-64. [PMID: 24518925 DOI: 10.1016/j.taap.2014.01.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 01/09/2014] [Accepted: 01/22/2014] [Indexed: 11/28/2022]
Abstract
BACKGROUND Erionite has similar chemical and physical properties to amphibole asbestos, which induces autoantibodies in mice. Current exposures are occurring in North Dakota due to the use of erionite-contaminated gravel. While erionite is known to cause mesothelioma and other diseases associated with asbestos, there is little known about its effects on the immune system. OBJECTIVES We performed this study to determine whether erionite evokes autoimmune reactions in mice. METHODS Bone marrow derived macrophages (BMDM) were used to measure toxicity induced by erionite. Cytokine production by BMDM and splenocytes of C57BL/6 mice was examined by bead arrays and ELISA following exposure to erionite, amphiboles and chrysotile. Wild type C57BL/6 mice were exposed to saline, erionite, amphibole asbestos (Libby 6-Mix) or chrysotile through intratracheal instillations at equal mass (60μg/mouse). Seven months after exposure, sera were examined for anti-nuclear antibodies (ANA) and IL-17. Immunohistochemistry was used to detect immune complex deposition in the kidneys. RESULTS Erionite and tremolite caused increased cytokine production belonging to the TH17 profile including IL-17, IL-6, TGF-β, and TNF-α. The frequency of ANA was increased in mice treated with erionite or amphibole compared to saline-treated mice. IL-17 and TNF-α were elevated in the sera of mice treated with erionite. The frequency of immune complex deposition in the kidneys increased from 33% in saline-treated mice to 90% with erionite. CONCLUSIONS These data demonstrate that both erionite and amphibole asbestos induce autoimmune responses in mice, suggesting a potential for adverse effects in exposed communities.
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Affiliation(s)
| | - Chad Davis
- Department of Biological Sciences, Idaho State University, Pocatello, ID, USA
| | | | - Kok Wei Ng
- Department of Biological Sciences, Idaho State University, Pocatello, ID, USA
| | - Jean C Pfau
- Department of Biological Sciences, Idaho State University, Pocatello, ID, USA.
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Saini-Eidukat B, Triplett JW. MINERALS IN THE HUMAN BODY: Erionite and offretite from the Killdeer Mountains, Dunn County, North Dakota, U.S.A. Am Mineral 2014; 99:8-15. [PMID: 30542213 PMCID: PMC6287636 DOI: 10.2138/am.2014.4567] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The carcinogenic potential of erionite has sparked concern about human exposure in areas where it is present in regional bedrock. The Arikaree Formation in western North Dakota contains altered tuffaceous units with authigenic zeolites. We sampled stratigraphic profiles in the Killdeer Mountains, Dunn County, North Dakota, to determine the distribution and chemical composition of zeolites. Powder X-ray diffraction, SEM/EDS and electron microprobe analyses were carried out on sample concentrates. Only samples stratigraphically in or below the distinctive burrowed marker unit were found to contain zeolites. Erionite and offretite were the most common zeolites identified, with offretite being more abundant based on frequency of measured Mg/(Ca+Na) ratios. Intermediate chemical compositions could be natural or due to intimate intergrowths of the two minerals. A better understanding is needed of the potential toxicity across the range of erionite and offretite compositions.
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Affiliation(s)
| | - Jason W. Triplett
- Department of Geosciences, North Dakota State University, Fargo, North Dakota 58108, U.S.A
- Environmental and Conservation Sciences Program, North Dakota State University, Fargo, North Dakota 58108, U.S.A
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