Understanding the extent of human health risks with an emphasis on carcinogenesis development attributable to potentially toxic chemicals is critical to effective prevention and mitigation strategies. Chromium (Cr), mainly the hexavalent chromium (Cr (VI)), is a chemical associated with cancer when found in drinking water, making it a major public health issue. This study assessed a possible carcinogenic human health risk among the general population due to exposure to total or hexavalent chromium. We performed a systematic review of the international scientific literature, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol to determine the human risk of cancer mortality and morbidity. In total, 76 articles were checked for eligibility, 13 of which were included in the final systematic review. Only scientific articles from January 2000 to November 2022 published on PubMed were included. Data from both epidemiological ecological studies (Relative Risk and Rate Ratio—RR and Standardized Mortality Rate—SMR) and epidemiological case studies (Lifetime Cancer Risk—LCR, Incremental Lifetime Cancer Risk—ILCR, Cancer Risk—CR, Hazard Quotient—HQ, Hazard Index—HI, Health Risk Assessment—HRA, Disability-Adjusted Life Year—DALY, and Chronic Daily Intake Index—CDI) were included for the overall assessment of carcinogenicity in the general population. According to most articles, there is credible evidence that hexavalent chromium via water is indicated as a major contributor to the global burden of cancer in humans. Some of them emphasize malignant neoplasms in the lung, liver, stomach, and genitourinary system. Although the health index data of the case studies are based on a limited number of samples, they raise concerns about the possibility of an increase in the degree of carcinogenesis. However, there are significant limitations due to the lack of information on the dose and duration of exposure in the target group. Further research involving extensive analysis of the association of the two variables is needed, which depends on more complete information extraction and advanced methodologies.
Specific continuous layers of zeolitic tuff in Ntrista stream location of Petrota area of Evros region (NA11) and pure natural crystals of heulandite (HEU1) from the collection of the Department of Mineralogy-Petrology-Economic Geology, School of Geology, Aristotle University of Thessaloniki, have been investigated. The X-Ray Diffraction analyses showed that the sample NA11 consists of 86 wt% HEU-type zeolite, 4 wt% micas+ clay-minerals, 4 wt% quartz, 2 wt% christobalite and 4 wt% feldspars, while the sample HEU1 is pure heulandite crystal. The mineral-chemistry was determined by SEM-EDS microanalyses. The zeolite of the NA11 sample is Ca-rich clinoptilolite and its chemical formulae is Ca1.8K1.0Mg0.7Na0.5Al6.4 Si29.5O72·21H2O, while the zeolite of the sample HEU1 is heulandite and its chemical formulae is Ca3.6Na1.0Κ0.2Sr0.2Ba0.1Al8.1Si27.6O72·21H2O. The uptake ability of the samples was measured by the AMAS method (Ammonium Acetate Saturation). The two examined materials show high uptake ability. The measured value for the zeolitic tuff NA11 is 231 meq/100g, while for the heulandite crystal (HEU1) is 296 meq/100g. For the determination of the cesium sorption a CsNO3 solution (concentration 500 mg/L), labelled with small activity of 137Cs, and pH 2-12 was used. The sorption of the cesium by the two materials, was determined by measuring the gamma radiation emitted by the 137Cs tracer. The zeolitic tuff presents higher uptake ability of radioactive cesium than the pure heulandite crystal, whereas the sorption of radioactive cesium is not significantly affected by the pH values of the initial solutions in the range pH 2-12.The clinoptilolitic zeolitic tuff NA11 is suitable material for various environmental, agricultural and industrial applications.
Diatomitic and clastic-volcanoclastic marly samples from the Paranisia area of Limnos Island, were studied mineralogically by X-ray diffraction (XRD), chemically by X-ray fluorescence spectroscopy (XRF) and morphologically by scanning electron microscopy (SEM-EDS), together with some physical properties such as the insulation block density, specific surface area and porosity. The diatomaceous samples were classified as porcelaneous or clayey (moler type) diatomite. Opal-CT forms microplates disseminated in the groundmass and are diagenetically formed in expense of opal-A dissolution. The purest diatomaceous beds have been transformed into opaline beds (opal-CT-rich rocks), whereas the clayey beds were not influenced by diagenetic transformations. The studied diatomites from Limnos Island are suitable materials for environmental uses, as an absorbent, for the production of insulation bricks or as lightweight aggregates.
Fifteen (15) zeolitic rocks from Karlovassi-Marathokampos basin of Samos Island (Greece) were investigated for their mineralogical composition by X-Ray Diffraction (XRD) method. According to EU Regulation No 651/2013, clinoptilolite of sedimentary origin with ≥80 wt% clinoptilolite, ≤20 wt% clay minerals, free of fibres and quartz, can be used as feed additive for all animal species. Depending on the zeolites, the zeolitic rocks are grouped to those containing: Clinoptilolite (33-86 wt%), clinoptilolite (59 wt%) + mordenite (20-21 wt%), clinoptilolite (22 wt%) + analcime (29 wt%), clinoptilolite (17 wt%) + phillipsite (27 wt%), analcime (29-70 wt%), mordenite (62%) and chabazite (63 wt%). None of the clinoptilolite-containing rocks (10 samples) meet the requirements of the EU Regulation No 651/2013, and thus cannot be used as feed additives for all animal species and consequently as nutrition supplements, since all of them contain 2-5 wt% quartz, two of them 20-21 wt% mordenite (fibrous zeolite), nine of them <80 wt% clinoptilolite (17-73 wt%) and two of them >20 wt% clay minerals (27-42 wt%). Although the EU Regulation No 651/2013 refers to clinoptilolite of sedimentary origin, using the presence or absence of quartz and fibrous minerals, none of the five mordenite, analcime and chabazite containing zeolitic rocks, can be used as feed additives and nutrition supplements, since all of them contain 2-6 wt% quartz and one of them contains 62 wt% mordenite (fibrous zeolite).
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