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Chemical compositions of a range of groundwaters with naturally high fluoride concentrations. The table also gives the modelled dominant species in the waters and fluorite saturation indices, calculated using PHREEQC..

Chemical compositions of a range of groundwaters with naturally high fluoride concentrations. The table also gives the modelled dominant species in the waters and fluorite saturation indices, calculated using PHREEQC..

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The element fluorine has long been recognised to have benefits for dental health: low-fluoride intake has been linked to development of dental caries and the use of fluoride toothpastes and mouthwashes is widely advocated in mitigating dental health problems. Fluoridation of water supplies to augment naturally low fluoride concentrations is also un...

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... these generally low concentrations, fluoride in surface waters can be much higher in geothermal areas. Many alkaline lakes in the East African Rift Valley for example have concentrations of the order of tens to hundreds of mg L -1 (up to 1980 mg L -1 ; Table 4). ...
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... concentrations are lower in the humid tropics because of high rainfall inputs and their diluting effect on groundwater chemical composition. Table 4 shows the chemical compositions of a range of typical high-fluoride groundwaters from various parts of the world. The data illustrate the dominance of Na over Ca in most, though not all, waters and the high concentrations of HCO 3 that typify high-fluoride waters. ...
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... formation of complexes may have ramifications for human health for example in aluminium-bearing waters, where the total fluorine may be much higher than the measured ionic fluoride. Thus aluminium fluoride may stabilise the fluoride as a complex ion, but if these complexes are broken down during metabolism they could release both F -and potentially toxic Al. Table 4 gives the saturation indices for fluorite for each of the waters. Fluorite solubility is likely to control the upper limits of fluoride concentrations in most natural waters. ...

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... Although anthropogenic emissions from certain industrial processes can also contribute fluoride from the atmosphere to the water (Chapman 1996;García and Borgnino 2015), most of the dissolved fluoride has a geogenic origin. Therefore, the occurrence of fluoride in natural waters mainly depends on its abundance in the local lithology (Edmunds and Smedley 2013). Several authors have explored the mechanism of fluoride release into the solution from solid phases (e.g., Jacks et al. 2005;Chae et al. 2006;Chaïrat et al. 2007;Zhu et al. 2009;Keshavarzi et al. 2010;Borgnino et al. 2013;García et al. 2014). ...
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Dental fluorosis is a disease associated with prolonged intake of high concentrations of fluoride, mainly by drinking water consumption. In a rural region in NW Argentina, several localities are supplied for domestic use by surface waters with variable contents of dissolved F⁻ (from 0.3 to 3.1 mg L⁻¹) of geogenic origin. Dental fluorosis, from very mild to severe, has been registered in the population according to the spatial variability of dissolved F⁻. In this work, statistical models demonstrated that the concentrations of dissolved F⁻ that determine the occurrence of dental fluorosis (and its severity) depend on the concentrations of dissolved Ca²⁺. In children and adolescents, the probability of presenting this disease, at any degree, increases with age and dissolved F⁻; whereas moderate-to-severe degree is controlled by an inverse relationship between dissolved F⁻ and Ca²⁺. This last result was also obtained in the group of adults, for any degree of dental fluorosis. Thus, for a particular concentration of dissolved F⁻, as dissolved Ca²⁺ increases, the probability of developing dental fluorosis decreases. The findings of this work could be useful to adjust the current regulations, since guidelines of dissolved F⁻ in drinking water for different degrees of dental fluorosis are not considered, nor the relationship between F⁻ and Ca²⁺.
... The concentration is mostly high in almost all locations of the study area which should be within 1.5 mg/l for drinking water stated by WHO. Edmunds and Smedley (2013) stated the best range suited for luoride in the drinking water is 1 mg/l. Fluoride concentration in water can be classiied into the following classes: < 1 mg/l as low luoride; 1-1.5 mg/l acceptable limit of luoride; and > 1.5 mg/ as high luoride. ...
... Ca +2 and Mg +2 are dominant as the result of weathering of silicate rocks like granite gneiss (Adimalla et al., 2018a(Adimalla et al., , 2018b(Adimalla et al., , 2018c. These samples also show high EC with high TDS which determines the major role of rock-water interaction along with longer residential time (Dehbandi et al., 2018;Edmunds & Smedley, 2013). ...
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... T he natural occurrence of high concentrations of fluoride in groundwater is a global health concern potentially affecting 100's of millions of people, predominantly in the Global South [1][2][3][4][5][6][7][8][9][10][11][12][13][14] . The health effects resulting from the long-term ingestion of fluoride include dental and skeletal fluorosis, in many cases severely impacting the lives of those affected [15][16][17][18][19][20][21] . ...
... High fluoride concentrations are often found naturally in aquifers in acidic igneous basement rocks, volcanic and geothermal rocks as well as derived sedimentary deposits and metamorphic rocks with high pH and alkalinity, low calcium concentrations, higher temperatures, and/or long groundwater residence times 9,27,28 . High pH promotes the desorption of fluoride from clay; hydroxyl anions (OH − ) exchange with F − in F-bearing minerals; and bicarbonate (HCO 3 − ) reacts with fluorite (CaF 2 ) to release fluoride, though dissolved calcium can bind with fluoride and remove it from dissolution to again form fluorite 9,29-31 . ...
... High pH promotes the desorption of fluoride from clay; hydroxyl anions (OH − ) exchange with F − in F-bearing minerals; and bicarbonate (HCO 3 − ) reacts with fluorite (CaF 2 ) to release fluoride, though dissolved calcium can bind with fluoride and remove it from dissolution to again form fluorite 9,29-31 . Furthermore, higher temperatures (e.g., geothermal waters) enhance chemical weathering 31 and longer groundwater residence times provide more time for reactions to take place 9 . Arid and semi-arid regions are generally more likely to contain high fluoride groundwaters on account of higher pH and alkalinity as well as longer residence times 2,14 . ...
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... Fluoride is more soluble in acid soils and primarily accumulates in the leaf [56,57]. According to a related study conducted by Edmunds and Smedley (2013), the fluoride content of the leafy part of vegetables grown in this area is significantly higher than the fluoride content of the fruits and tubers [58]. Seeds accumulate very little fluoride in comparison to other parts of the plant. ...
... Fluoride is more soluble in acid soils and primarily accumulates in the leaf [56,57]. According to a related study conducted by Edmunds and Smedley (2013), the fluoride content of the leafy part of vegetables grown in this area is significantly higher than the fluoride content of the fruits and tubers [58]. Seeds accumulate very little fluoride in comparison to other parts of the plant. ...
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... While in PC5, moderate loading factors were Turbidity (0.50) calculated for the district Ghotki, whereas SO 4 2− (0.53) and Fe (0.61) were recorded for the Nawab Shah, respectively ( Table 2). High loading factors of Cl − and SO 4 2− in PC2 may also be attributed to dissolution of evaporites (gypsum and halite), sulfide oxidation, and anthropogenic input of industrial activities, whereas NO 3 − in PC2 and Fe in PC3 and PC5 could be related to agricultural practices and inputs of domestic waste (Edmunds and Smedley, 2013;Xiao et al., 2016;Hou et al., 2020;Rashid et al., 2021) (see Supplementary Figure S2). The moderate factors of variables in PC3, PC4, and PC5 could be associated with anthropogenic activities leading to influence the hydrochemical characterization of groundwater aquifers (Fan et al., 2014;Zhang et al., 2019;Huang et al., 2020a;Zhang M. et al., 2020). ...
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... High Fconcentration in drinking water may cause a dental enamel of higher porosity and lower mineral content (dental fluorosis) (Alvarez et al., 2009, Edmunds andSmedley 2013). The ion Ba 2? is responsible by the barium toxicity in mammals as they are promptly absorbed from the gastrointestinal tract due to the high permeability of the intestinal mucosa (DiBello et al., 1991). ...
... Fconcentration [ 1.5 mg/L was found at AJS groundwater (Table 2), as well in other Brazilian natural mineral waters (Bonotto 2016), and in some aquifer systems worldwide (Smedley et al., 2002;Reddy et al., 2010, Edmunds andSmedley 2013, etc.). Additionally, Fordyce et al. (2007) and Edmunds and Smedley (2013) pointed out that the waters enriched in Na ? , K ? ...
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... The fluoride concentration is higher in groundwater because water dissolves the fluoridebearing mineral while percolating and flowing in the subsurface aquifer through rock-water interaction (Falvey, 1999;Marghade et al., 2020;Rango et al., 2009). Fluoride-rich groundwaters are closely associated with fractured crystalline basement aquifers containing many fluoride-bearing minerals at a certain depth (Edmunds & Smedley, 2013;Jacks et al., 2005;Rukah & Alsokhny, 2004;Subba Rao, 2003, 2017. Fluoride levels in groundwater can range from 0 to 35 mg/L in nature (World Health Organization, 1994). ...
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The menace of fluorosis is quite anticipatable for the people of the Puruliya district because of the excessive fluoride level in the groundwater. More than 80% of the population is rural, and 85% depend on groundwater as their single means of drinking water. Therefore, the current paper aims to determine the block-wise distribution of villages and populations based on the fluoride level of groundwater and associated health risk in the Puruliya district. The study is based on the report on village-level fluoride concentration from the National Rural Drinking Water Mission Survey. Blocks of Puruliya District are categorized according to the World Health Organization's classes of different fluoride concentrations and related health impacts. For each category, the population is calculated based on the census of India 2011 data. The mapping of the severity of fluoride-exposed villages and populations is prepared using Arc. GIS 10.5. Our study found that 35.39% of the population is in danger of getting fluorosis through ingesting fluoride-rich water. Applying a geospatial approach to study the fluoride distribution is very significant in identifying the endemic fluoride region and safe areas for the entire district, which will help to take proper management remedies regarding prevention and control of fluorosis in the concerned district.
... The basement rocks of the Eastern Ghats (which is a part of the study area) are granitic in composition. These rocks contain fluorite (CaF 2 ) and fluoride-containing biotite where fluoride substitutes for hydroxyl in the crystal lattice and mobilizes fluoride to the groundwater (Edmunds and Smedley, 2005;Farooq et al., 2018). ...
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Reservoir temperature Geochemistry of thermal water Indian geothermal systems Isotope systematics of geothermal waters A B S T R A C T To meet the increase in global energy consumption in an eco-friendly and sustainable manner more emphasis has been put on non-conventional energy resources, such as geothermal energy. India aims to significantly increase the contribution of geothermal energy to its energy mix. In order to do so, a thorough investigation into the geothermal resources of India is of utmost importance. Here we report the hydrochemistry and stable isotope systematics of thermal springs located in the state of Odisha, Eastern India, to evaluate the feasibility of harnessing the geothermal reservoirs. Water chemistry and stable isotope ratios of surface-, non-thermal and thermal water were studied to access the origin and chemical evolution of the thermal waters. The waters had a pH of 5.9 to 8.6 and a suggested meteoric origin based on their δ 18 O and δD ratios. Chemical geothermometers indicate reservoir temperatures in the range 96-128 • C, caused by a high radiogenic heat production at depth coupled with the deep circulation of meteoric water through faults. Processes such as water-rock-interaction, mixing of thermal water with the shallow groundwater and mineral precipitation and dissolution were found to be responsible for the chemical evolution of the thermal waters.
... Globally, an estimated 200 million people are at risk of exposure to F − levels exceeding the recommended limit of 1.5 mg/L in drinking water (Edmunds and Smedley 2013;NRC 2006;WHO 2016). The Ethiopian Rift Valley is one of the hot spots for F − exposure in groundwater (Rango et al. 2014(Rango et al. , 2020Demelash et al. 2019) that exceeds Ethiopia's maximum permissible level of 1.5 mg/L for F − in drinking water (Ethiopian Standards Agency 2013). ...
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Many essential/beneficial elements including Ca, Mg, Sr, B, and F⁻ play an important role in bone health. While elevated levels of F⁻ are known to cause adverse health effects on bone, variations of these elements in nails that can be influenced by F⁻ toxicity are unclear. This study aims to assess the relationship between the concentrations of Ca, Mg, Sr, and B in fingernails and bone quality of F⁻exposed individuals in the Ethiopian Rift Valley. Bone quality was determined using an ultrasonic method that measures the magnitude of speed of sound (SOS) conduction in cortical bones. We collected fingernails of individuals aged 10 to 70 years old (144 males and 123 females) in 25 communities drinking water from wells with F⁻ concentrations ranging from 0.3 to 15.5 mg/L (mean 7 ± 4.7 mg/L). Fluoride concentrations in drinking water were measured using the ion selective electrode (ISE) method. Concentrations of Ca, Mg, Sr, and B in fingernails were measured using Inductively Coupled Plasma Spectrometry (ICP-MS). Mean Ca, Mg, Sr, and B concentrations (mg/kg) in fingernails were 740 ± 425, 98 ± 89, 1.33 ± 1.6, and 0.63 ± 1.2, respectively. Each element was categorized by F⁻ concentrations (mg/L) in drinking water as groups: 1 (< 2), 2 (> 2–6), 3 (> 6–10), and 4 (> 10–15.5). The mean concentrations of these elements in fingernails increased with the increase in F⁻ concentrations in drinking water, and significant differences were observed in the means of groups 1 and 4 for all elements, group 2 for Sr, and group 3 for B. The correlation trends for SOS measurements with these elements in fingernails at different age groups decrease with high F⁻ exposure and the negative associations are more pronounced at older (51–70) ages. These associations suggest F⁻related bone deterioration in the studied subjects, which is noticeable with the increase in age. The study demonstrates the effect of F⁻ exposure on bone quality, and the studied fingernail elemental variations in populations chronically exposed to F⁻ in drinking water.
... Fluoride is one of the ubiquitous elements found on Earth and is one of the few elements that may cause a harmful impact on human and animal health Yadav et al. 2019). Among many other diseases with geo-environmental significance, the link between fluoride in drinking water and incidence of dental and skeletal fluorosis is a well-established relationship in medical geology (Yadav et al. 2019;Edmunds and Smedley 2013;Chandrajith et al. 2012). Although many trace elements enter the human body through food, air, medicines, and cosmetics, fluoride mainly enters the body through drinking water (Edmunds and Smedley 2013). ...
... Among many other diseases with geo-environmental significance, the link between fluoride in drinking water and incidence of dental and skeletal fluorosis is a well-established relationship in medical geology (Yadav et al. 2019;Edmunds and Smedley 2013;Chandrajith et al. 2012). Although many trace elements enter the human body through food, air, medicines, and cosmetics, fluoride mainly enters the body through drinking water (Edmunds and Smedley 2013). Therefore, fluoride in drinking water has now become a major problem in many terrains, particularly in the tropical belt. ...
... Therefore, fluoride in drinking water has now become a major problem in many terrains, particularly in the tropical belt. A higher prevalence of endemic fluorosis was reported in countries such as China, India, Sri Lanka, Mexico, and in many countries in tropical Africa (Daesslé et al. 2009;Edmunds and Smedley 2013;Vithanage and Bhattacharya 2015). Endemic fluorosis is one of the common health issues in the dry zone of Sri Lanka, leading to serious clinical manifestations (Rubasinghe et al. 2015;Ranasinghe et al. 2019;Chandrajith et al. 2020). ...
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Excessive fluoride levels in drinking water poses serious global health issues. Decreased male fertility rates are reported from fluorosis endemic regions globally. This study aimed to examine potential impacts of chronic exposure to fluoride in drinking water on male reproductive parameters. The case–control study was based on recruits from a fluorosis endemic region, Anuradhapura, and a non-endemic region, Colombo, (n = 15 fertile with proven paternity and 15 subfertile, from each region) in Sri Lanka. Seminal fluid analysis (SFA) was performed according to WHO guidelines. Fluoride ion-selective electrodes quantified serum fluoride levels, while sandwich ELISAs assayed seminal IL-4 and IL-1β cytokines. SFA between the fertile groups did not differ significantly (p > 0.05). Compared to the non-endemic subfertile group (NESG), the endemic subfertile group (ESG) manifested highly significant higher serum fluoride concentration, percentage of morphologically normal spermatozoa (p < 0.001), and liquefaction time (p < 0.02), while the contrary was true of semen volume (p < 0.001). Significantly lower spermatozoa count (p < 0.02), motility (p < 0.001), and viability (p < 0.002) detected in the ESG compared to the NESG, was reiterated by significant negative correlation established between serum fluoride concentration and aforementioned three spermatozoa parameters in ESG (p < 0.05). Seminal plasma IL-4 and IL-1β levels did not significantly differ between ESG and NESG (p > 0.05). The source of drinking water significantly differed in ESG (67% well water) and NESG (60% pipe-borne water) (p < 0.02). These findings were indicative of serum fluoride concentration as an important contributory factor for male factor subfertility in a fluorosis endemic region in Sri Lanka.