High Fluoride Concentrations Research Articles

In vitro wearing away of orthodontic brackets and wires in different conditions: A review

IntroductionThe release of metallic ions from orthodontic brackets and wires typically depends on their quality (chemical composition) and the medium to which they are exposed, e.g., acidic, alkaline, substances with a high fluoride concentration, etc. This review examines corrosion and wear of orthodontic brackets, wires, and arches exposed to different media, including: beverages (juices), mouthwashes and artificial saliva among others, and the possible health effects resulting from the release of metallic ions under various conditions. ObjectiveThis review aims to determine the exposure conditions that cause the most wear on orthodontic devices, as well as the possible health effects that can be caused by the release of metallic ions under various conditions. SourcesA search was carried out in the Scopus database, for articles related to oral media that can corrode brackets and wires. The initial research resulted in 8,127 documents, after applying inclusion and exclusion criteria, 76 articles remained. ConclusionStainless steel, which is commonly used in orthodontic devices, is the material that suffers the most wear. It was also found that acidic pH, alcohols, fluorides, and chlorides worsen orthodontic material corrosion. Further, nickel released from brackets and wires can cause allergic reactions and gingival overgrowth into patients.

Application of data-mining technique and hydro-chemical data for evaluating vulnerability of groundwater in Indo-Gangetic Plain.

Vulnerability of groundwater is critical for the sustainable development of groundwater resources, especially in freshwater-limited coastal Indo-Gangetic plains. Here, we intend to develop an integrated novel approach for delineating groundwater vulnerability using hydro-chemical analysis and data-mining methods, i.e., Decision Tree (DT) and K-Nearest Neighbor (KNN) via k-fold cross-validation (CV) technique. A total of 110 of groundwater samples were obtained during the dry and wet seasons to generate an inventory map. Four K-fold CV approach was used to delineate the vulnerable region from sixteen vulnerability causal factors. The statistical error metrics i.e., receiver operating characteristic-area under the curve (AUC-ROC) and other advanced metrices were adopted to validate model outcomes. The results demonstrated the excellent ability of the proposed models to recognize the vulnerability of groundwater zones in the Indo-Gangetic plain. The DT model revealed higher performance (AUC=0.97) followed by KNN model (AUC=0.95). The north-central and north-eastern parts are more vulnerable due to high salinity, Nitrate (NO3-), Fluoride (F-) and Arsenic (As) concentrations. Policy-makers and groundwater managers can utilize the proposed integrated novel approach and the outcome of groundwater vulnerability maps to attain sustainable groundwater development and safeguard human-induced activities at the regional level.

Evaluation of Enamel Acid Resistance and Whitening Effect of the CAP System.

This study aimed to compare the effectiveness of a novel professional tooth-strengthening system and a conventional caries-prevention method that involved the use of high fluoride concentrations, to determine whether the system has a whitening effect. Bovine tooth-enamel samples were treated with fluoride gel (conventional APF method) or a mixture of citric acid gel, calcium phosphate (α-TCP), and fluoride gel, referred to as the CAP system; these treatments were performed to generate an acid-resistant layer on the enamel surface. For the evaluation of the acid resistance, a cyclic experiment, involving a 1-h remineralization and a 24-h acid treatment, was conducted thrice after the treatments. The height profiles were observed using a 3D-measuring laser microscope and the hardness was evaluated by Vickers hardness test. The morphological changes in the surface and cross-section of the enamel were observed by scanning electron microscopy. To evaluate the whitening effect, the enamel was ground until the color of the underlying dentin was recognizable; the CAP system was applied once, and the color change was measured using a color difference meter. As a result, it was confirmed that an acid-resistant layer was formed on the tooth surfaces treated with the CAP system, and a whitening effect was obtained.

Fluoride concentration in teas derived from Camellia Sinensis produced in Argentina.

To evaluate the fluoride concentration and pH of tea derived from Camellia sinensis produced and commercialized in Argentina. Forty-eight varieties of tea (black (n = 16), green (n = 21), red (n = 7), and white (n = 4)) commercialized in the form of leaves or tea bags were acquired. One bag or 2.0 ± 0.05g of each product was infused for 5min in 200mL of distilled boiled water. The F- concentration was determined using an ion-selective electrode and pH was measured using a pH meter. The found fluoride concentrations ranged from 0.1 to 9.7µg/mL and the pH ranged from 2.7 to 5.1. A higher fluoride concentration was observed in the leaves group (2.75 ± 2.65µg/mL) compared to tea bags (1.10 ± 0.82µg/mL) (p < 0.05). Regarding the type of tea, green and black tea were richer in F- than red and white tea. Fluoride and pH appeared not to be correlated (Pearson test). All the studied tea samples presented fluoride concentrations greater than the threshold recommended for drinking water. The pH proved to be low, which could be a risk for erosive tooth wear.

Effectively arsenic(V) and fluoride removal in geothermal water using magnetic Fe3O4@MgO nanoparticles

High residual concentration of arsenic and fluoride is a tricky problem to be solved in the process of reinjection after geothermal water utilization. We develop a method to simultaneously remove As(V) and F− from geothermal water using magnetic Fe3O4@MgO adsorbent, fabricated via a one-step method. The effects of pH, contact time, adsorbent dose and temperature on the removal efficiency were investigated systematically. The results show that the Fe3O4@MgO composite has a wide range of pH (2–11), ultrafast removal dynamics (As(V): 2 min; F−: 30 min), and high removal efficiency (As(V): 99.9%; F−: 96.6%). The adsorption kinetics follows the pseudo-second-order kinetics model, and the adsorption isotherm model fits Freundlich. The adsorption capacity of As(V) and F− can reach 123 and 98.4 mg/g, respectively. The exchange of As(V) and F− with Mg-hydroxyl groups hydrolysis by MgO was determined the adsorption mechanism. The Fe3O4@MgO adsorbent was capable of achieving the adsorption efficiency as high as 99.9% for As(V) and 97.3% for F− in real geothermal water, respectively. Hence, the proposed Fe3O4@MgO composite exhibited as an excellent adsorbent for the remediation of As- and F-contaminated geothermal water.

Origin and migration of fluoride in the area of the Aluto Volcanic Complex (Main Ethiopian Rift)

Fluoride-enriched ground and surface waters represent a major health risk for the local population in many areas along the East African Rift. The present study investigates the origin of fluoride and the reason for its accumulation in the rift waters, following two hypotheses: (i) fluid-rock-interactions release fluoride from minerals into the water and (ii) magmatic-derived fluoride-containing liquids and gases migrate along permeable fault zones until they dissolve in ground- and surface water or be released to the atmosphere.Rock-, gas, water-, soil-, and plant samples were collected from the area within and close by the Aluto Volcanic Complex, which is part of the Main Ethiopian Rift. Most analyzed waters showed fluoride concentrations above the drinking water limit (>1.5 mg/L) with the highest values in hot springs (up to 70 mg/L) and the geothermal well (76 mg/L). In the solid phase, a high fluoride content was found in acid volcanic rocks (ignimbrite: 4391 ppm; rhyolite: 3248 ppm) as well as in pumice (up to 1955 ppm). The fluoride content of soil samples collected within the volcanic complex varied between 82 and 1036 ppm, whereas former lake sediments from outside the Aluto Volcanic Complex showed higher fluoride contents ranging from 674 to 8171 ppm.Identified fluoride-rich minerals are various amphiboles (about 3 wt.-% F−), fluor-apatite (about 3 wt % F−), minerals of the fluor-caphite group (about 5 wt.-% F−), parisite (up to 9 wt.-% F−), and fluorite (CaF2). Elevated fluoride concentrations were also measured in some gas samples from fumaroles (up to 50 ppm) and in plant samples collected next to the fumaroles (up to 65 ppm). Leaching experiments of solid samples with deionized water demonstrated that fluoride can easily be mobilized from pumice and sediments but hardly from consolidated rocks. This fluoride release increased with temperature (up to 150 °C) and correlated roughly with dissolved silica indicating the binding of some fluoride to the amorphous or weakly crystalline silica fraction.Based on these results it was concluded that fluoride migrates via different pathways through the environment: At the depth of the magma chamber during magmatic differentiation fluoride enriches initially in the magmatic melt and accumulates in some late-crystallizing minerals of igneous rocks such as fluorite or mica. Upon volcanic eruption fluoride is predominantly incorporated in the glass (ignimbrite) and ash phase (pumice). On the surface, these rocks are exposed to weathering and fluoride leaches partly out into the aqueous phase. Soft and porous rocks such as pumice release fluoride first whereas hard extrusive/igneous rocks are less prone to weathering and retain the fluoride. Pumice and (lake) sediments might act both, as source and as sink for fluoride in the area. Although some fluoride might drain from the surface into the deeper subsoil, we conclude that magmatic fluids (liquid and gas) contribute more substantially to the overall fluoride ground water content because (i) of the much higher fluoride content in deep geothermal waters and hot springs as compared to surface-near waters; (ii) active geothermal surface manifestations located along fault zones indicate that fluids migrate from deep magmatic intrusions (as gas and liquid) towards the surface, where fluoride dissolves in groundwater; (iii) and the good correlation between bicarbonate (deriving from dissolution of magmatic CO2) and fluoride content in all analyzed water samples.

Study on Waste Acid Modificated Industrial Solid Waste Aluminum Ash to Prepare Environmental Functional Materials to Remove Fluoride Ions in Wastewater

C-SAAoa particles synthesized by simple and low-cost calcining industrial solid waste aluminium ash combined with waste oxalic acid modification process show excellent performance in fluoride removal speed and adsorption capacity. Their adsorption capacity on fluoride was determined at about 180.57 mg/g at pH 3.0, which was among the highest reported values in the literature. It was determined that the adsorption mechanism of fluoride on C-SAAoa particles followed mechanisms such as ion exchange, electrostatic action, and the surface - OH groups played a major role in the fluoride removal process. C-SAAoa particles can effectively remove fluoride, even in the presence of a certain concentration of competing anions. At the same time, the material possesses good cycling performance, and can still maintain 78.9% of the initial adsorption capacity in the longitudinal for eight recycles. Therefore, it may have the potential to become a promising adsorbent as a supplement to industrial solid waste resource-based utilization processes and also for fluoride removal in small-scale treatment facilities or wastewater with high fluoride concentrations.

Fluoride Removal in Synthetic Drinking Water by Electrocoagulation Using Aluminum Electrodes

Fluoride is recognized as an essential constituent in the human diet. Low fluoride concentration could prevent dental problem while higher fluoride concentration will cause dental and skeletal fluorosis. This study aimed to remove fluoride in synthetic drinking water by electrochemical system. It had been performed at laboratory scale using fluoride synthetic water. The process consisted to optimize the fluoride removal in drinking water using the Aluminum electrodes. The effects of operating conditions such as the initial ion fluoride concentration, current density or intensity, contact time, and NaCl amount were studied. Experimental results showed that with the initial concentration of 15 mg/L using the optimal intensity (1.5 A), an admitted residual concentration (1.5 mg/L) was observed during 45 min of electrolysis while maximum fluoride removal percentage of 100 % was achieved for 60 min. The variation of energy consumption from 1.18 to 22.35 Wh showed that the electrocoagulation can be applied using photovoltaic energy for fluoride treatment in drinking water.

Hydrochemical appraisal of fluoride contamination in groundwater and human health risk assessment at Isa Khel, Punjab, Pakistan

Fluoride contamination in the groundwater of Pakistan is widespread with serious potential health consequences. We determine the groundwater of Isa Khel Tehsil upper Indus plain for drinking purposes and fluoride contamination by collecting 236 water samples from the water supply schemes supplied with groundwater. Results show that the majority of the parameters exceed the standard concentration of potable water. The concentration of fluoride ranges from 0.02 to 5.35 mg/L with an average of 1.8 mg/L, and about 58.5% of the collected samples have higher fluoride concentration than the allowed limit for drinking purposes. Fluoride pollution index results show that about 48.73% of samples have a high level of risk, 41.95% samples of the study area have medium level and only 9.32% of the water samples show low level of fluoride contamination. The health risk assessment due to fluoride contamination was computed based on chronic daily intake (CDI) and hazard quotient (HQ). For adult’s variation in CDI and HQ ranges from 0.001–0.15 mg/kg/day and 0.001–2.55 respectively whereas in children it ranges from 0.001–0.29 mg/kg/day and 0.02–4.84. Health risk assessment parameters indicate that in the case of adults, about 40.25% of samples exceeded the maximum allowed value of hazard quotient i.e., HQ > 1, while for children, about 66.95% of samples have HQ > 1, which means that children are at higher risk than adults because of higher vulnerability to fluoride contamination in drinking water. Thus, there is a need for effective groundwater monitoring and management in the study region to safeguard residents from various illnesses associated with drinking water with varying fluoride concentrations. • Worldwide in groundwater, fluoride contamination is becoming a challenge. • Higher fluoride level in drinking water cases dental and skeletal fluorosis at alarming rate. • Evaluation of two hundred and thirty-six water samples indicate more than 50 percent samples not fit for drinking.

Health Risk Assessment in Mexican Children Exposed to Fluoride from Sweetened Beverages.

The primary source of fluoride exposure is groundwater, but evidence suggests that beverages and food are additional fluoride sources. Intake of these products at an early age affects the optimal functioning of soft organs. An increase in sweetened beverage consumption by the pediatric population has been reported, suggesting an increase in fluoride exposure. The objectives of this study were to determine the fluoride concentrations in beverages and analyze the risk to human health from fluoride exposure to sweetened beverages consumed by children. Eighty-two sugar-sweetened beverages produced in different Mexican states were analyzed. The fluoride determination was carried out with an ion-selective electrode. The highest fluoride concentration was 1.92mg/L; 73.2% of beverages showed fluoride values above permitted limits. Low-cost beverages had the highest fluoride values, suggesting that the water used for their production does not comply with fluorine regulations. According to the risk assessment in children from 3 to 6years, the daily consumption of juices and sodas with concentrations that exceeded the normative of 0.7mg/L could represent a risk to dental fluorosis development. It is crucial to control fluoride and regulate its concentrations in beverages for children to ensure food safety, especially in areas of endemic hydrofluorosis.

Knowledge Level and Consumption Behavior of Native Plants, Meats, and Drinking Waters with High Fluoride Concentrations about the Relation to the Potential Health Risk of Fluoride in Lamphun Province Thailand: A Case Study

Fluoride exposure from natural, agricultural, and industrial sources has harmed people living in fluoride-affected areas. Fluoride accumulates in the human body after being exposed to it through the food chain. The population consisted of 371 community health volunteers who were surveyed and chosen based on personal fluoride information. Only 39 residents were chosen to be interviewed and take part in the trial, which involved drinking fluoride-containing groundwater (&gt;1.5 part per million: ppm) and urine testing that revealed urine fluoride level (&gt;0.7 ppm). In addition, 47 biological samples and eight commercially bottled water specimens were examined. The information was gathered in four ways: (1) a questionnaire-based survey of fluoride knowledge, (2) food consumption behavior with locally grown vegetables, fruits, poultry, and meat, and commercially bottled water produced by groundwater in fluoride-affected areas, (3) a semi-food frequency questionnaire, and (4) fluoride content measurements using an ion-selective electrode. According to the analyses, the participants ranged in age from 51 to 60 years, with approximately 60.38% of them female and born and raised in polluted areas. The majority of subjects had a low level of fluoride knowledge (65.23%). The respondents’ primary source of drinking water (100.00%) was commercially bottled water; they chewed camellia sinensis 11.56% of the time (1 to 5 years) and they drank tea 9.16% of the time (during 1 to 5 years). Sus scrofa domesticus was responsible for the intake of vegetables and fruits, whereas Brassica chinensis, Jusl var para-chinensis (Bailey), and Tsen and Lee were responsible for the intake of poultry and animal flesh. They were all purchased at a local farm. The hazard quotient was greater than one, and the fluoride concentration (ppm) ranged between 75.00% (0.29–5.20), 57.14% (0.01–0.46), 88.89% (0.07–0.91), 100.00% (0.43–3.07), 100.00% (0.58–0.77), 42.86% (0.12–0.62 ppm.), 60.00% (0.11–1.44), and 33.33% (0.10–0.80) in drinking water, fruit, young and mature plants. Fluoride ingestion may pose a health concern. Under the 95th percentile condition, 74.47% consumed water with a high fluoride level, vegetables and fruits, and poultry and meats.

Simultaneous and efficient removal of fluoride and phosphate in phosphogypsum leachate by acid-modified sulfoaluminate cement

The high concentration of fluoride and phosphate in phosphogypsum leachate is harmful to the environment and ecosystem. Thus, there is a need to develop feasible materials or technologies to remove both fluoride and phosphate in acidic phosphogypsum leachate. In this study, sulfoaluminate cement (SC) was used to simultaneously remove fluoride and phosphate in wastewater based on its moderate alkalinity and rich content of metal elements (Ca, Al and Fe, etc). The acidized sulfoaluminate cement (ASC) composite was prepared through modifying SC with hydrochloric acid, which can increase the specific surface areas of the raw SC, as well as the activity of the metal elements in SC. Compared with other coagulants, ASC showed excellent removal performance for fluoride and phosphate, such as higher removal efficiency, better effluent quality, and accelerated settling rate. The fluoride and phosphate removal performances of ASC herein were investigated at different dosages, pH values, coexisting substances, and initial concentrations. As a result, ASC exhibited wide pH adaptability and satisfactory selectivity for fluoride and phosphate. The possible removal mechanisms of fluoride and phosphate by ASC included chemisorption, ion exchange, and precipitation. The main end products associated with fluoride were fluorite (CaF2), aluminum fluoride (AlF3), and iron trifluoride (FeF3). The main final products amid phosphate removal, on the other hand, were brushite (CaHPO4·2H2O), aluminophosphate ((H3O)·AlP2O6(OH)2), silicocarnotite (Ca2SiO4·Ca3(PO4)2) and iron phosphate (Fe(H2PO4)3). More importantly, ASC can effectively treat the phosphogypsum leachate at a wide range of concentrations, and the concentrations of phosphate and fluoride in the effluents were lower than 0.5 mg P L−1 and 4 mg L−1, respectively. To sum up, ASC is a competitive candidate to treat wastewater with high fluoride and phosphate content, such as phosphogypsum leachate.

Fluoride Content of Matcha Tea Depending on Leaf Harvest Time and Brewing Conditions

Matcha, or powdered green tea (Camellia sinensis) of the Tencha type, is popular all around the world, and its consumption continues to rise. Because of its unique cultivation method, it is rich in phytochemicals and has many health-promoting properties; it contains high concentrations of polyphenols, theanine and chlorophyll. Tea, and by extension matcha, contains numerous minerals, one of which is fluorine. Under physiological conditions, this mineral plays a significant role in hard tissue mineralisation processes. However, even in low concentrations, with prolonged exposure, fluoride can accumulate in the body, leading to a number of harmful effects. The aim of this study was to evaluate, for the first time, the fluoride content of the matcha infusions from different harvests, brewed using water at different temperatures (25 °C, 70 °C, 80 °C and 90 °C). The content of fluoride ions was measured by the potentiometric method. The fluoride content ranged from 3.36 to 4.03 mg/L and was dependent on both the leaf harvest time and brewing temperature. The concentration of this mineral in the dry powder ranged from 118.39 to 121.65 mg/kg. Irrespective of the water temperature or harvest time, matcha was found to have a high fluoride content, with particularly high concentrations being noted in the powder itself.

Adsorption Characteristics and Charge Transfer Kinetics of Fluoride in Water by Different Adsorbents

Water containing high concentrations of fluoride is widely distributed and seriously harmful, largely because long-term exposure to fluoride exceeding the recommended level will lead to fluorosis of teeth and bones. Therefore, it is imperative to develop cost-effective and environmentally friendly adsorbents to remove fluoride from polluted water sources. In this study, diatomite (DA), calcium bentonite (CB), bamboo charcoal (BC), and rice husk biochar (RHB) were tested as adsorbents to adsorb fluoride (F‐) from water, and this process was characterized by scanning electron microscopy (FEI-SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR). The effects of pH, dosage, and the initial mass concentration of each treatment solution upon adsorption of F‐ were determined. Kinetic and thermodynamic models were applied to reveal the mechanism of defluoridation, and an orthogonal experiment was designed to obtain the optimal combination of conditions. The results show that the surfaces of CB, BC, and RHB have an irregular pore structure and rough surface, whereas DA has a rich pore structure, clear pores, large specific surface area, and high silica content. With regard to the adsorption process for F‐, DA has an adsorption complex electron interaction; that of CB, BC, and RHB occur mainly via ion exchange with positive and negative charges; and CB on F‐ relies on chemical electron bonding adsorption. The maximum adsorption capacity of DA can reach 32.20 mg/g. When the mass concentration of fluoride is 100 mg/L, the pH value is 6.0 and the dosage is 4.0 g/L; the adsorption rate of F‐ by DA can reach 91.8%. Therefore, we conclude that DA soil could be used as an efficient, inexpensive, and environmentally friendly adsorbent for fluoride removal, perhaps providing an empirical basis for improving the treatment of fluorine-containing water in the future.

Monitoring and prediction of high fluoride concentrations in groundwater in Pakistan

Concentrations of naturally occurring fluoride in groundwater exceeding the WHO guideline of 1.5 mg/L have been detected in many parts of Pakistan. This may lead to dental or skeletal fluorosis and thereby poses a potential threat to public health. Utilizing a total of 5483 fluoride concentrations, comprising 2160 new measurements as well as those from other sources, we have applied machine learning techniques to predict the probability of fluoride in groundwater in Pakistan exceeding 1.5 mg/L at a 250 m spatial resolution. Climate, soil, lithology, topography, and land cover parameters were identified as effective predictors of high fluoride concentrations in groundwater. Excellent model performance was observed in a random forest model that achieved an Area Under the Curve (AUC) of 0.92 on test data that were not used in modeling. The highest probabilities of high fluoride concentrations in groundwater are predicted in the Thar Desert, Sargodha Division, and scattered along the Sulaiman Mountains. Applying the model predictions to the population density and accounting for groundwater usage in both rural and urban areas, we estimate that about 13 million people may be at risk of fluorosis due to consuming groundwater with fluoride concentrations >1.5 mg/L in Pakistan, which corresponds to ~6% of the total population. Both the fluoride prediction map and the health risk map can be used as important decision-making tools for authorities and water resource managers in the identification and mitigation of groundwater fluoride contamination.

Color stability and microhardness alteration of irradiated dental enamel treated with a high fluoride concentration toothpaste.

Radiotherapy (RT) is a kind of head and neck cancer (HNC) treatment, which is associated to the habit of smoking and can develop collateral effects in the oral cavity, such as the increase of caries prevalence. This study evaluated the color alteration, the microhardness, and the remineralizing potential of high fluoride concentration toothpastes on irradiated teeth. Forty bovine teeth were used (6 × 6 × 2mm) and after color (EasyShade, VITA) and microhardness initial readings were separated into two groups: exposed to cigarette smoke and non-exposed. All samples were submitted to RT (30Gy) and to cariogenic challenge. New color and microhardness readings were done. After RT (60Gy), the samples were submitted to simulated toothbrushing (73,000 cycles = 5years of brushing) with two different toothpastes: conventional (1450ppm) and high fluoride concentration (5000ppm). Final color and microhardness readings were done after brushing. Data were analyzed with 2-way ANOVA with repeated measures and Tukey's test (p < .05). There was no color difference after RT, nor after brushing (p > .05). However, after brushing, microhardness values increased for the samples treated with high fluoride concentration toothpaste (p < .05). Radiotherapy did not influence the teeth color, and the high fluoride concentration toothpaste presented remineralizing potential; therefore, it could be used on the caries prevention related to HNC radiation. Considering its remineralizing potential, toothpastes with high fluoride concentration could be a proper alternative for caries prevention in patients undergoing radiotherapy.

Evaluation for internal consistency in the thermodynamic network involving fluorite, cryolite and villiaumite solubilities and aqueous species at 25°C and 1 bar

AbstractThermodynamic data are constrained by the interrelated thermodynamic equations in addition to the observational measurements and their uncertainties. The consequence is a network of thermodynamic properties that can be evaluated for their internal consistency. In this study, three fluoride minerals that can cause high fluoride concentrations in groundwaters are evaluated for their solubilities and their internal thermodynamic consistency with calorimetric, isopiestic and electrochemical measurements: fluorite, CaF2, cryolite, Na3AlF6, and villiaumite, NaF. This evaluation involves the three solids and 13 aqueous species, the free ions of Ca2+, Na+, Al3+ and F–, and the hydroxido and fluorido complexes of Al3+, and the CaF+ ion pair. For the fluorite–cryolite–villiaumite–aqueous species network, the number of components is minimal, and the solubility studies are mostly of high quality. Re-evaluations of original data using PHREEQC helps to broaden the quantitative evaluation of thermodynamic properties and to resolve apparent discrepancies. A check on this thermodynamic network shows that through a careful appraisal of the literature, a highly consistent set of values can be derived. The resultant infinite-dilution solubility-product constants at 25°C and 1 bar are: for fluorite solubility, logKsp = –10.57 ± 0.08; for cryolite solubility, logKsp = –33.9 ± 0.2; and for villiaumite solubility, logKsp = –0.4981 ± 0.003.

A Review of Defluoridation Techniques of Global and Indian Prominence

Fluoride(F-) is the 13thmost abundant chemical element in the Earth's crust which has been widely recognised for its health benefits at low concentration but poses a serious threat to public health at very high doses. The world health organization has set the fluoride guideline limit of 1.5 mg/l in drinking water. Globally, over 260 million people drink water with high fluoride concentrations. Widespread distribution and high fluoride levels in the potablewater in most of the areas of the world has prompted substantial research and mitigation efforts to address the growing public health concerns related to fluoride contamination. With the recent advances in science, various defluoridation methods such as adsorption, ion exchange, precipitation-coagulation, membrane processes, biological defluoridation and even integrated approaches have been developed for the management of fluoride-contaminated aquatic environments. This review provides an up-to-date insight into thedefluoridation techniques developed and implemented throughout the world and highlightsthe advantages and disadvantages of each technique.The literature survey confirms that despite developing so many novel techniques for defluoridation over the years, there is still no effective fluoride removal technique that can achieve the desired results in a cost-effective and sustainable manner. Therefore, development of a commercially practical, economical, and sustainable technique is required to prevent people especially the most vulnerable from poor and developing nations (dependent on untreated water)from the hazards of fluoride contamination.

DETERMINATION OF FLUORIDE CONCENTRATIONS LEVEL IN DRINKING GROUND WATER IN SHENDI CITY, RIVER NILE STATE, SUDAN

Fluoride is one of the anions that endanger human health at concentrations lower and higher than the standard, also is one of the main problems in most parts of the world, where about 200 million people from 25 countries are exposed to high or low concentrations of fluoride from groundwater sources. . This descriptive and analytical study was conducted in shendi City to determine concentrations level of fluoride in ground water. 150 samples of ground water were tested per season (50 samples for each season), The water samples were collected from ground water sources (wells), distribution system and storage facilities that are used directly for drinking purpose in the community per seasons. Analyzing of samples had been completed according to standard methods for examinations of water, in this study used photometer device for determination concentrations of fluoride. Our study revealed that: the quality of ground water in study area is low fluoride content and below the optimum levels that recommended by WHO and SSMO guidelines for drinking water and seasonal variations have effects on fluoride’s solubility and concentrations. Based on the findings of this study we recommend that: community must not depend totally on ground water as main source for fluoride, and community in study area should be use other sources for fluoride intake to obtain on daily required amount of fluoride for protection the health.

Fluoride exposure and its potential health risk assessment through ingestion of food in the mica mining areas of Jharkhand, India

The study was taken up to assess the fluoride concentration in the plant and animal based food items (cereals, pulses, vegetables, milk, chicken, egg and fish) in the vicinity of mica mining areas of Jharkhand which is rich in fluoride bearing minerals like biotite, muscovite, apatite, etc. The highest fluoride concentrations were observed in the wheat and chicken samples amongst the plant and animal origin foods, respectively. The leafy vegetables accumulated higher fluoride content as compared to other vegetables. The estimated daily intake (EDI) exceeded the Provisional tolerable daily intake (PTDI) of fluoride of 0.04 mg/kg/day in some of the wheat and rice samples. For the assessment of non-carcinogenic risk of fluoride, Hazard Quotient (HQ) and Hazard Indices (HI) were calculated as per United States Environmental Protection Agency methodology. The HQ of wheat and rice were highest amongst all the food items and contributed about 69% of the total risk. The hazard index (HI) for the adult population in view of the content of fluoride in the food samples ranged from 0.409 to 3.04 considering all the locations. HI exceeded unity in 60% of the locations, indicating non-carcinogenic risk to the populace. Higher HIs were assessed in the locations under the influence of mica mining activities.