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Fluoride in Drinking Water: A Review on the Status and Stress Effects
Critical Reviews In Environmental Science and Technology
Abstract
‘Water is life,’ so central to human life, yet over one billion people across the world have no access to safe drinking water. Of late, there has been increasing global attention focused on resolving water quality problems especially in developing countries, as the lack of access to clean water denies the most essential of all rights, the right to life. The latest estimates suggest that around 200 million people, from among 25 nations the world over, are under the dreadful fate of fluorosis. India and China, the two most populous countries of the world, are the worst affected. India is plagued with numerous water quality problems due to prolific contaminants mainly of geogenic origin and fluoride stands first among them. The weathering of primary rocks and leaching of fluoride-containing minerals in soils yield fluoride rich groundwater in India which is generally associated with low calcium content and high bicarbonate ions. The unfettered ground water tapping exacerbates the failure of drinking water sources and accelerates the entry of fluoride into groundwater. Most of the scientific literature substantiates the benefits of low fluoride concentrations in preventing dental decay. However, as a surprising paradox, incidence of dental, skeletal and crippling skeletal fluorosis was reported in India with average fluoride concentrations as low as 0.5, 0.7 and 2.8 ppm respectively. Fluorosis, turns out to be the most widespread geochemical disease in India, affecting more than 66 million people including 6 million children under 14 years age. Though fluoride has spread its tentacles in 36,988 habitations and the number of people falling prey to fluoride poisoning have been steadily increasing, an exact exposure-health relationship is yet to be properly elucidated. There is an essential relation between poverty and fluorosis as malnutrition is found to play an aggressive role in its severity.
... The condition is cumulative and gradual (WHO, 2019), and the pathological bone modifications it causes may decrease overall life expectancy (Walser et al., 2020). Prolonged fluoride intake (exceeding ten years) can lead to mild skeletal changes, with fluoride accumulation slowing and reaching a plateau after approximately 55 years of age (Ayoob and Gupta, 2006;Ponikvar, 2008). If fluoride intake ceases, the reduction of fluoride levels in bone occurs gradually (Khairnar et al., 2015). ...
... It can also be present as a result of human activities such as industrial pollution (e.g. aluminium industry) or as an artificial additive in foodstuffs, water or dental care products (WHO, 1992;Ayoob and Gupta, 2006;Ghosh et al., 2013;Zohoori and Duckworth, 2017). Despite this wide variety of sources, water is considered to be the main source of fluoride, with concentrations varying between geographic regions and influenced by parameters such as pH, temperature and water hardness (WHO, 1984;Ayoob and Gupta, 2006;Barbier et al., 2010;Zohoori and Duckworth, 2017;Chowdhury et al., 2019). ...
... aluminium industry) or as an artificial additive in foodstuffs, water or dental care products (WHO, 1992;Ayoob and Gupta, 2006;Ghosh et al., 2013;Zohoori and Duckworth, 2017). Despite this wide variety of sources, water is considered to be the main source of fluoride, with concentrations varying between geographic regions and influenced by parameters such as pH, temperature and water hardness (WHO, 1984;Ayoob and Gupta, 2006;Barbier et al., 2010;Zohoori and Duckworth, 2017;Chowdhury et al., 2019). Groundwater in volcanic regions is particularly rich in fluoride. ...
La fluorose osseuse est une pathologie liée à l’ingestion prolongée de grandes quantités de fluorure, qui entraine notamment une augmentation de la densité des os. Cette maladie sévit souvent à l’état endémique dans certaines zones volcaniques où les eaux souterraines contiennent des doses élevées de fluor. Cette étude vise à proposer une approche multidisciplinaire combinant observations paléopathologiques et analyses archéométriques pour le diagnostic de la fluorose osseuse des restes humains provenant de sépultures secondaires à crémation de la période romaine (IIe siècle av. J.-C. – Ier siècle apr. J.-C.). L’échantillon étudié est composé de 45 individus originaires de la ville de Cumes (Campanie, sud de l’Italie), dans la région volcanique des Champs Phlégréens. Les lésions pathologiques ont été enregistrées selon un protocole d’observations macroscopiques. La détection et les mesures de fluor ont été effectuées par Spectroscopie d’émission atomique de plasma induit par laser (LIBS). Les résultats ont permis de confirmer que les os des habitants de Cumes présentaient des concentrations élevées de fluor et des lésions pathologiques très probablement liés à la fluorose osseuse. 49 % des sujets étudiés a été classé dans les catégories de suspicion modérée à forte de fluorose, indiquant une potentielle intoxication environnementale. Cela est probablement liée au caractère volcanique de la région et à la consommation des eaux souterraines.
... In many safely managed drinking water systems, fluoride is added to a concentration of approximately 0.7 mg/L [1] as it binds with calcium in enamel to help build strong teeth and bones [2]. The beneficial range of fluoride in drinking water is 0.5 mg/L to 1.5 mg/L [3,4]. Fluoride above 1.5 mg/L can leach calcium from teeth and jaw bones [2]. ...
... Dental fluorosis is indicated by mottled teeth and increases the risk of dental caries. Skeletal fluorosis is a chronic metabolic bone disease [7] indicated by an increase in bone mass and density, bony outgrowths at bone surfaces, and the development of cartilaginous lesions in cancellous bones [3,8]. Additionally, tensile strength, energy required for fracture, and modulus of elasticity may be lowered with skeletal fluorosis [7]. ...
... Additionally, tensile strength, energy required for fracture, and modulus of elasticity may be lowered with skeletal fluorosis [7]. Around the world, over 150 million people suffer from some form of fluorosis [3]; a recent assessment estimated that 167 million people consume high (>1.5 mg/L) fluoride water, but provide a confidence interval that encompasses the prior estimate [9]. The majority of people affected by the debilitating effects of fluorosis are from low-and middleincome regions where there is a need for safely managed water systems [4]. ...
High fluoride concentrations in drinking water affect millions of people around the world. The World Health Organization recommends a fluoride concentration in drinking water below 1.5 mg/L. Fluoride above this concentration can cause long-term problems known as fluorosis, such as mottled teeth and increased risk of dental caries, or skeletal deformities. Rural communities near Arusha, Tanzania have high fluoride concentrations in their water; although, they typically consume even more tea. While tea has the benefit of disinfection by boiling, the tea leaves also impart additional fluoride; our tests with local water and tea show tea to increase fluoride from 3.2 to 6.4 mg/L. In the region, tea is traditionally prepared with milk. To better determine the total fluoride intake in the area, we measured tea prepared with and without milk. Tea infused with water and mixed with milk had 0.3 mg/L or 15% more fluoride compared to the fluoride from the constituents. Tea infused with water and milk had 0.8 mg/L or 40% less fluoride compared to the fluoride from the constituents. This apparent difference in fluoride is small, but the consistent difference from preparations warrants further investigation including reactions that may have caused less fluoride infusion or unknown interferences. Surveys also indicated that residents do not have water within 30 min of their residents, which places them into the Limited category for drinking water as defined by the Joint Monitoring Program.
... Water represents just one of the numerous elemental materials that contain fluoride (Fig. 14.1). Fluoride may additionally enter water from other sources, including business operations, runoff from agriculture, and of course some natural events (Ayoob and Gupta 2006). ...
... Mineral dissolution, industrial wastes, and volcanic emissions all cause fluoride to progressively build up in the environment. The earth's crust has between 300 to 900 parts per million meters of fluoride, with the mantle thought to have 200 times more of the mineral (Ayoob and Gupta 2006). Fluoride is thus present in magma and magmatic gas, simultaneously uncontrolled and interacting with the element hydrogen, silicon, and ammonium. ...
... It is thought that the main cause of adult fluoride poisoning in communities that consume large amounts of tea is fluoridated tea. Most of the fluoride exposure in many modern nations comes from toothpaste (usually 1,000-2,500 ppm), dental gel (12,300 ppm), varnish (23,000 ppm), and water that has been treated by the government (Ayoob and Gupta 2006;Brouwer et al. 1988, Ali et al. 2016). ...
Fluoride is a mineral which occurs naturally and often is ordinarily found in soil, rocks, and water. Fluoride may additionally enter water from other sources, including business operations, runoff from agriculture, and of course some natural events. Fluoride from such sources may disintegrate and find its way into ground water as well as surface water whenever precipitation or melting snow penetrates into the earth. It is called inevitable fluoride, which may be found in various amounts in a wide range of water supplies worldwide. Long-term excessive fluoride consumption has been scientifically connected to a number of physical problems, such as thyroid malfunction along with brain damage. Water poisoned with fluoride poses a serious risk to human health and necessitates extremely efficient water and environmental management. Fluoride poisoning is a serious health concern since fluoride is released into the environment by anthropogenic activities. The efficacy of fluoride removal is contingent upon chemicals in nature, topographical, and economic variables unique to each location; hence, actual applications may deviate from the theoretical framework. A process that satisfies requirements in one place could not meet those in another. Depending on the requirement, a public–private collaboration project should be carried out with sufficient preparation, oversight, and ongoing reinforcement.
... The groundwater in primarily humid, tropical regions of the world has been shown to be contaminated with fluoride ions. According to Ayoob and Gupta (2006), China, South Asian countries, and African countries are among those with this kind of climate. Nonetheless, estimates indicate that fluoride-contaminated groundwater water is being consumed by at least 200 million people globally (Podgorski and Berg, 2022;Ayoob and Gupta 2006). ...
... According to Ayoob and Gupta (2006), China, South Asian countries, and African countries are among those with this kind of climate. Nonetheless, estimates indicate that fluoride-contaminated groundwater water is being consumed by at least 200 million people globally (Podgorski and Berg, 2022;Ayoob and Gupta 2006). Synthesis of global data shows that fluoride pollution in groundwater exceeds the WHO maximum allowed level of 1.5 mg L −1 in more than 100 nations. ...
... Because of its extremely high surface area to weight ratio and abundance of tiny pores, activated alumina, which is derived from aluminum oxide, has many small pores running through it (Fawell et al. 2006). Comparably, numerous sorbents based on aluminum have demonstrated improved adsorption capacity and increased surface area, which raises fluoride removal (Ayoob and Gupta 2006). Additionally, defluoridation has been tried with aluminum-based adsorbents combined with minerals and oxides of calcium, iron, and manganese (Vithanage and Bhattacharya 2015). ...
In most places of the world, groundwater is the primary supply for a variety of uses. A significant problem is the presence of high concentrations of specific ions, which render groundwater unfit for use in a variety of ways. One such ion that affects people's health in more than 100 countries worldwide is fluoride. Groundwater contains varying amounts of fluoride, which can be attributed to either natural or man-made sources, or a mix of the two. Fluoride exposure has long-term effects on human health including skeletal fluorosis, which weakens and bends bones but also dental fluorosis, which causes teeth to turn brown, thus it's important to periodically check the amount of fluoride from groundwater sources and take action to get it down to the legally allowed range of 0.6–1.5 mg l−1. Fluoride can be extracted either in-situ or ex-situ from groundwater using a variety of techniques. However, the specific conditions of the area, such as the groundwater quality and the anthropogenic or natural cause of contamination, will determine which approach is best. Since fluoride contamination is a major and pervasive issue in many regions of the world with largely natural and preventable causes, public education and defluoridating groundwater before consumption are crucial for maintaining global health.
... Tropical countries are mainly affected by high fluoride concentrations in groundwater (Raju et al., 2015), where the per capita consumption of water is higher because of the prevailing climate. Although the cases of fluorosis have been documented worldwide, the problem is quite severe in densely populated countries like India (Ayoob & Gupta, 2006). In India, cases of endemic fluoride has been reported by various workers in different parts of the country like, from Nalgonda and Guntur districts of Andra Pradesh (Rao et al., 2021;Yasaswini et al., 2024), Garhwa district, Jharkhand (Anshuman & Subodh, 2020)), Brahmaputra valley of Assam (Gogoi et al., 2021), Rajnanadgaon district of Chhattisgarh (Lal et al., 2023); semi-arid regions of Gujrat (Mandal et al., 2021); Mahendergarh and Jhajjar districts of Haryana (Singh et al., 2022), Tumkur district of Karnataka (Thabrez & Parimalarenganayaki, 2024), Palghat District, Kerala (Gayen et al., 2024), Nandurbar district, Maharashtra (Patil et al., 2024), Mandla District, Madhya Pradesh ; Dausa District, Rajasthan (Dauji et al., 2023), Tirunelveli District, Tamil Nadu (Gopalakrishnan et al., 2012); Indo-Gangatic plains (Jha & Tripathi, 2021;Sulaiman et al., 2024) and Hooghly District of West Bengal (De el al., 2024). ...
... A weak positive correlation between pH and fluoride ( Fig. 10) implying some dependence relationship and signifies that an increase in alkalinity accelerates fluoride enrichment in groundwater (Adimalla et al., 2019;Narsimha & Sudarshan, 2017). A weak positive correlation of fluoride with Na + and HCO 3 − suggests both ion exchange (Subha Rao, 2016) and dissolution of rocks and leaching of fluoride-bearing minerals affect its higher concentration (Adimalla et al., 2018;Ayoob & Gupta, 2006;Li et al., 2019;Subba Rao et al., 2017). The same ion exchange process responsible for Na + enrichment also leads to a decline in Ca 2+ concentration in groundwater, as indicated by a moderate negative correlation (Table 2 & Fig. 10); thus, a higher calcium content favors a low fluoride concentration in groundwater (Adimalla et al., 2019). ...
Fluoride contamination of groundwater exerts serious health concerns in developing countries like India, where surface water resources in general are not considered for domestic consumption. The present investigation attempts to evaluate the groundwater quality in terms of fluoride contamination in Deobhog and adjoining areas in Gariaband district, Chhattisgarh. A total of 68 groundwater samples were collected both in the pre- and post-monsoon period and analyzed for different physicochemical parameters like Temperature, pH, EC, TDS, Na⁺, K⁺, Ca²⁺, Mg²⁺, HCO3⁻, NO3⁻, Cl⁻, SO4²⁻, and F⁻. The results reveal that the cation abundance is in the order of Ca²⁺ > Na⁺ > Mg²⁺ > K⁺, and that for anions, it is HCO3⁻ > Cl⁻ > SO4²⁻ > NO3⁻ > F⁻. Hydrochemical characterization shows that the water is dominantly calcium bicarbonate type in general, irrespective of their fluoride concentration. The source of the dissolved constituents in water is identified to be due to rock-water interaction. Hydrochemical processes like ion exchange, along with carbonate and silicate weathering, are responsible for major cations and anions concentrations in fluoride-rich water. Changes in alkalinity of water accelerate the dissolution of fluoride from fluoride-bearing mineral phases, thus increasing the concentration in water. The highest concentration of fluoride is observed at Nangaldehi village (4.9 mg L⁻¹ post-and 3.83 mg L⁻¹ pre-monsoon), in the north-eastern part where dental fluorosis is noted in residents of the affected area. Lithounits like mafic granulite, Dongargarh granite, charnockite, etc. have a higher concentration of fluoride due to the presence of minerals such as apatite, biotite, hornblende, etc., confirmed through detailed petrographic studies. The fluoride from these sources also dispersed into the residual soil developed over the weathered rocks. The water in the area is observed to be undersaturated with fluoride, which signifies the area’s proneness to more fluoride contamination in the near future. The contaminated aquifers are structurally controlled, and the shallow, unconfined aquifers are less contaminated with fluoride than those that are present at an elevation around 200 m above mean sea level. This study provides first-hand information about the fluoride contamination in the area and established its geogenic origin. It also emphasizes to explore the possibility of alternate surface water sources for the affected areas.
... Children may have higher HQ values than adults because to their lower body weight. At 2-6 years old, this hazardous disease is more prevalent than at 18 [5,21,55]. Dental fluorosis is typically determined by fluoride exposure up to age 8-10, as it stains developing teeth in the jawbones and under the gums. ...
... The current study found that the highest concentration was 3.80 mg/L, which reduces the likelihood of developing crippling skeletal fluorosis. The likelihood of developing this condition depends on a number of factors, including the amount of fluoride consumed, the type and solubility of the fluoride, the age of the individual at the first exposure, and their response to the fluoride [4,55]. ...
Groundwater contamination with fluoride is a considerable public health concern that affects millions of people worldwide. The rapid growth of urbanization has led to increase in groundwater contamination. The health risk assessment focuses on both acute and chronic health consequences as it investigates the extent and effects of fluoride exposure through contaminated groundwater. Fluoride exposure, especially in endemic locations, has serious health consequences, including dental and skeletal fluorosis. An accurate assessment of these hazards is essential for public health planning and mitigation actions. The present study uses Monte Carlo Simulation (MCS) and an Artificial Neural Network (ANN) model to perform a Probabilistic Health Risk Assessment on populations in fluoride-endemic areas. Analysis of the results of the study reveals that the concentration of fluoride ranged from 0.58 to 3.80 mg/L with an average of 2.30 mg/L across the Kasganj district, which was higher than permissible limits given by BIS and WHO. The highest value of hazard quotient of 3.29 for Children is found to be in the Durga Colony area, while the lowest value of the hazard quotient of 0.31 for adults is found to be in the Nadrai Gate area. The assessment of health risks revealed a high probability of non-carcinogenic disease from the consumption of groundwater containing fluoride. The ANN model has the R² value of 0.9989 in training and 0.9870 in testing while RMSE value in training and testing was 0.02230 and 0.0267. The findings suggest that before being used, the groundwater in Kasganj, Uttar Pradesh, India, needs to be treated and made drinkable. The results emphasize the critical need for ongoing monitoring, public education initiatives, and implementing feasible mitigating techniques to lower fluoride exposure. The findings show that this hybrid model is excellent at addressing the numerous uncertainties associated with fluoride use, hence improving the reliability of health risk estimates in fluoride-endemic locations. The results offer vital information to help policymakers and local health officials create focused measures to safeguard public health in Kasganj.
... Excessive F intake during early childhood can lead to dental fluorosis (Nizam et al., 2022), characterized by discoloration and pitting of the teeth, which may affect appearance and function (Dar and Kurella, 2024). Prolonged exposure to high F levels can result in skeletal fluorosis, a more severe condition involving pain, stiffness, and damage to bones and joints (Ayoob and Gupta, 2006). ...
Groundwater contamination is a significant global challenge, particularly in arid and semi-arid regions where groundwater is a primary source for drinking and irrigation. This contamination is closely associated with human health risks, potentially leading to severe diseases and long-term health consequences. In this study, the groundwater quality of the Nubian Aquifer System (NAS) in the Shendi area, Sudan, is assessed to evaluate health risks linked to nitrogen compounds (NO₂, NO₃, NH₃) and fluoride (F). The analysis integrates self-organizing maps (SOM), principal component analysis (PCA), and Monte Carlo-based health risk simulations. SOM analysis revealed distinct clustering patterns in groundwater samples, identifying three major hydrochemical trends. PCA indicated that elevated NO₃ concentrations were localized, primarily associated with agricultural runoff, while NO₂ and NH₃ reflected pollution from both agriculture and wastewater. High fluoride concentrations were linked to geogenic sources, particularly water-rock interactions with fluorine-bearing minerals. The Monte Carlo simulation assessed probabilistic health risks, revealing higher mean hazard quotients (HQs) and hazard index (HI) values for children compared to adults. Children’s mean HI of 1.06 significantly exceeds the safe threshold, indicating potential non-carcinogenic health hazards. Sobol sensitivity analysis identified the most influential parameters in shaping health risks, including average exposure time, body weight, and exposure duration, with strong parameter interactions amplifying these effects. Among contaminants, NO₃ and F contributed the most to cumulative HI values. These findings underscore the urgent need for targeted interventions, such as advanced water treatment, stricter pollution controls, and public health awareness programs to mitigate groundwater contamination and protect vulnerable populations.
... The corrosion resistance of Mg alloys was enhanced by 45.2% through the in situ synthesis of ZrO 2 achieved by incorporating K 2 ZrF 6 into the electrolyte [23]. While strategies like in situ synthesis mitigate particle agglomeration issues, the toxicity of electrolyte additives and their disposal protocols remain critical considerations for industrial scalability [24]. These aspects, though beyond the scope of the current study, highlight the need for future investigations into greener alternatives for PEO processes. ...
This study investigates the enhancement of corrosion resistance in magnesium-lithium alloys through plasma electrolytic oxidation (PEO) coatings incorporating ZnF2 via in situ synthesis. By adjusting Zn²⁺ concentrations (4–16 g/L) in a zirconium salt-based electrolyte, ceramic coatings with tailored ZnF2 content, thickness, and porosity were fabricated. The optimal Zn²⁺ concentration of 12 g/L yielded a ZnF2-rich coating with isolated pores and enhanced densification (inner layer resistance Ri = 3.01 × 10⁴ Ω⋅cm²), achieving a corrosion current density (icorr) of 4.42 × 10⁻⁸ A/cm² and polarization resistance (Rp) of 8.5 × 10⁵ Ω⋅cm², representing a 354-fold improvement over untreated LA103Z. Higher Zn²⁺ concentrations (16 g/L) induced interconnected pores and ZnO formation, degrading corrosion resistance. Long-term immersion (168 h in 3.5 wt% NaCl) confirmed the durability of Zn12 coatings (mass loss: 0.6 mg), while Zn4 and Zn16 coatings exhibited severe localized corrosion. The study demonstrates that balancing Zn²⁺ concentration optimizes ZnF2 passivation and pore isolation, offering a scalable strategy for Mg-Li alloy protection in corrosive environments.
... Fluoride toxicity can lead to dental fluorosis and skeletal fluorosis. Preventing geogenic contamination requires a multi-faceted approach that includes identifying areas with high levels of fluoride contamination, monitoring the fluoride migration and implementing appropriate in situ treatment technologies for affected groundwater sources (Ayoob and Gupta 2006;Hug et al. 2020). Numerical modeling aids in predicting, managing, and recommending remedial measures for groundwater pollution. ...
Geogenic contamination of fluoride severely impacts groundwater quality rather than industrial contamination. In this study, MODFLOW and MT3D applications are used to predict the groundwater flow and fluoride transport in Vaniyambadi and Ambur taluk in Tirupathur district. The conceptual model with three-layered aquifer system has been developed using visual MODFLOW flex v6.1 for an area of 955 km ² , with each grid cell sized 1000 m × 1000 m (51 rows × 49 columns). The model was calibrated from 2021 to 2022 for 30 -day period. Calibration of groundwater flow simulation after 365 days indicates that R ² value was 0.98; SEE, RMSE and NRMSE were 3.72 m, 27.87 m and 6.33%, respectively. MT3D simulation reveals that the value of R ² was 0.97, and RMSE and NRMSE were 0.23 m and 7.41%, respectively. The calculated fluoride concentration ranges between 0.3 and 3.49 mg/L; after 20 years of prediction, it was found to be 0.35–2.69 mg/L. The source of fluoride contamination is charnockite and granite-gneiss complex rock in Yelagiri Hill, which has 4 mg/L; after 20 years of simulation, the concentration was 9.91 mg/L and the plume extends up to 8 km towards the Palar River basin. Furthermore, HHRA has been used to evaluate the impact of fluoride on adults and children. According to the HHRA, hazard index (HI) was found to be more than one in many locations, causing serious health hazard. The results of these findings pave the way for further research on prevention of groundwater pollution due to geogenic migration.
... Fluoride levels between 0.5 and 1.5 mg/L are essential for human health, aiding bone and teeth development; however, concentrations above 1.5 mg/L pose severe health risks, including dental and skeletal fluorosis, hypertension, renal failure, and cancer [6][7][8][9][10]. With over 200 million people worldwide affected by high fluoride levels, the issue is critical in India, where 66 million, including 6 million children, are at risk [11][12][13][14]. The district of Balasore in Odisha, India, known for its agriculture, faces elevated fluoride contamination in groundwater due to the natural leaching from fluoride-bearing minerals like fluorite, mica, and apatite, which has been exacerbated by high alkalinity, low calcium levels, and sodium bicarbonate-type water [15][16][17]. ...
Groundwater fluoride levels have begun to be a global concern, posing significant challenges to the safe utilization of water resources and mitigating potential impacts on human health. Chronic exposure to elevated levels of naturally occurring fluoride in groundwater affects millions worldwide. Prolonged exposure can lead to health issues such as dental fluorosis and skeletal fluorosis. The World Health Organization (WHO) has established a maximum fluoride concentration guideline of 1.5 mg/L for drinking water. However, groundwater quality is not regularly tested in many regions, leaving communities unaware if water sources, such as wells and springs, contain harmful fluoride levels. In the Balasore area, Odisha, India, rising fluoride concentrations and spatial variability necessitate accurate predictions for effective groundwater management. This article proposes four predictive models, Random Forest (RF), Support Vector Regression (SVR), Gradient Boosting (XGBoost), and Stacking Regressor (SR), to estimate fluoride concentrations using physicochemical parameters and sampling depth as predictor variables. The performance of these models is assessed using the coefficient of determination (accuracy), mean square error (MSE), and mean absolute error (MAE). This article compared fluoride concentrations of machine learning models, including SR, RF, XGBoost, and SVR, in groundwater in Balasore, Odisha. Based on predictive performance, an SR model yielded the lowest MSE and MAE scores at 0.01817 and 0.10327, respectively. These findings underscore the superiority of ensemble learning approaches in addressing complex datasets and provide a robust framework for effective groundwater fluoride management. This article highlights the potential of advanced machine learning in improving public health outcomes in fluoride-affected regions. Finally, the recommendations for decreasing the fluoride concentrations and the guidelines for future research will be proposed.
... However, too much fluoride can lead to urolithiasis, fluorosis, nephrotoxic alterations, kidney problems in the stomach, and even cancer. [2][3][4][5] Fluoride ions (F − ) are excellent and suitable for treating osteoporosis and maintaining oral health. [6,7] Depending on the geographic area, fluoride concentrations in groundwater can range from 0.1 mg L −1 to well over 30 mg L −1 . ...
Fluoride ions (F⁻) are well‐known for their beneficial effects on oral health and their involvement in acting osteoporosis. But it is crucial to understand that consuming too much fluoride can of several adverse health effects. Dental fluorosis, urolithiasis, and even cancer can result from excessive fluoride exposure. This is why monitoring fluoride levels is so important. A 2,4‐dinitrophenyl hydrazine derivative of a BODIPY‐based aldehyde system (BDNP) is a sensitive, ratiometric, and selective naked‐eye sensor that we have developed for the quick detection of fluoride ions in biological and environment samples showed a significant color change from pink‐to‐grey and a significant redshift in absorbance maxima when interacting with fluoride ions. The notable color shift demonstrates the effectiveness of both BDNP and Poly‐BDNP in detecting fluoride ions. Interestingly, here we also showed that the ring‐opening polymerization (ROP) technique‐synthesized biodegradable and biocompatible ε‐Caprolactone homopolymer of BDNP (Poly‐BDNP) is a great system that can detect fluoride ions colorimetrically with a higher limit of detection (LOD) value than the monomer and rapid detection ability. Using the UV–visible spectroscopy study and the ¹H NMR spectroscopic titration technique, the interaction between BDNP and fluoride ions was examined. It was determined that the deprotonation of N–H protons triggers the intermolecular charge transfer (ICT) reaction, which results in the system's dramatic color change. The precision of both BDNP and Poly‐BDNP in detecting F⁻ ions with LOD values of 7.73 µM and 87.9 nM, respectively, is determined by the ratiometric absorbance change of the sensor during the sensing process.
... dental and skeletal decay. Excessive consumption of fluoride concentration leads to skeletal and dental fluorosis, blindness, stooped backs, crooked hands and legs (Ayoob & Gupta, 2006;Nagaraj & Masilamani, 2023;Yadav et al., 2019), thyroid, damage of brain, liver, endocrine glands, nervous and digestive system (Ma et al., 2011;Tor et al., 2009;Wang et al., 2023). Overall 260 million people in 25 developed and developing nations are affected due to excessive consumption of fluoride concentration in drinking water. ...
The direct consumption of fluoride-contaminated groundwater is increasing day by day without our knowledge escalating health risks. Therefore, it is imperative to carry out in-situ fluoride treatment where fluoride exposure is higher, rather than confining to small or large-scale industries. This necessitates of choosing appropriate purification methods and materials for effective treatment. The main objective of this research is to determine the adsorption/removal capacity of different proportions of activated red mud and bentonite mixture (RM:BEN) to remove fluoride from water. The characteristics of adsorption materials such as Red Mud (RM) and Bentonite (BEN) have been studied using Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray Spectroscopy (EDS), and X-ray diffractometer (XRD). These techniques reveal the morphological changes and a loss of crystalline nature, indicating the adsorption of fluoride on the RM:BEN mixture. Different mix proportions of activated red mud and bentonite such as 95%:05% (Mix-A), 90%:10% (Mix-B), 85%:15% (Mix-C), 80%:20% (Mix-D) was analysed to determine its fluoride adsorption characteristics. The results revealed that RM:BEN (Mix-C) mixture demonstrated a higher adsorption capacity of 2.65 mg/g than other mixtures. The adsorption isotherm and kinetics model, fitting the Langmuir and Pseudo-first-order models, suggest that monolayer physical adsorption occurs during fluoride removal. In-situ experiments showed that the maximum removal efficacy of RM:BEN (Mix-C) reached 89.52% on the 7th day under lateral flow conditions and 93.81% on the 10th day under longitudinal flow conditions.
... Fluoride ions are also released into natural water by several companies [7][8][9][10][11]. Fluoride in higher amount is detrimental to both humans and aquatic life [12][13][14][15][16][17][18]. And the same is reported in many regions of the world [19][20][21]. ...
Many effective and efficient treatment technologies have been applied for fluoride removal, but are found to be energy-intensive, expensive, requiring high operational and capital inputs, and need advanced technologies and skilled manpower. Adsorption, by contrast, is a flexible, efficient, simple-to design, and cost-effective treatment method. Many adsorbent types along with recently emerged nanoadsorbents represent a very promising treatment technology, but the limitations of this technology are still being studied. This implies that a lot of work is required by the scientific community to effectively apply this technology towards environmental sustainability, particularly in the water sector. In this work, thermally treated granular medium adsorbent prepared using combination of Regur soil, Omnibus soil and activated charcoal are used as adsorbent for defluoridation experiment. The fluoride reduction in aqueous solution after 1 h was 70% with adsorbent dosage of 4.8 g with 5 mg/L as the starting fluoride and 78% for groundwater sample with 3.6 mg/L starting fluoride. Reduction in fluoride was significantly observed for a pH range of 2 to 14, highest fluoride reduction was observed at pH range of 6 to 10. The isotherm model study gave better fit for Langmuir isotherm with regression parameter (R2 = 0.98) than the Freundlich isotherm (R2 = 0.84) which signifies monolayer adsorption. The study adhered to pseudo-second order kinetics. Surface morphology of the granular medium is also studied using SEM and EDAX and due to fluoride ions adsorption on the adsorbent surface there was textural change observed. This study indicated that thermally processesed soil and activated charcoal adsorbent was effective for defluoridation of aqueous solution with 70% reduction and groundwater with 78% reduction and hence can be used as cost effective adsorbent as naturally available materials with minimum processing are being used. However future research studies can be carried out with varying ratios of other efficient natural materials in order to increase the efficiency of defluoridation.
... Үүнээс үзэхэд говийн бүсийн 3 аймгийн худгийн усан дахь фторын ионы агуулга HCO 3 --Na + төрлийн усанд өндөр агуулгатай байна. Энэ нь гүний усанд натрийн гидрокарбонат давамгайлж байвал фторыг уусгах идэвх өндөр байдаг байна [17,18]. Үүнийг дараах урвалаар илэрхийлнэ: CaF 2 + 2NaHCO 3 -→ CaCO 3 + 2Na + + 2F -+ H 2 O + CO 2 (1) Корреляцийн коэффициент: Судалгаанд хамрагдсан гүний худгийн усны химийн найрлагад натрийн ион давамгайлж байгаа тохиолдолд фтор өндөр агуулгатай байна. ...
This study aimed to determine the fluoride ion content of deep well water in the Gobi region, compare it with established standards, and identify its origin. Within the scope of the work, we examined the physical and chemical parameters, as well as fluoride ion content of 144 deep well water samples collected from three provinces: Dundgobi, Dornogobi, and Umnugobi. The results were compared with the requirements set by the Mongolian drinking water standard MNS 0900:2018. According to measured pH values, the environment of the analyzed deep well water samples ranged from alkaline to neutral, whereas the hardness varied from very soft to very hard. It was also found that 63.2% percent of the samples did not meet the requirements of the drinking water standard MNS 0900:2018 for fluoride ion content. Specifically, 64.8% of the groundwater samples in Dundgobi province (F- , 0.7-7.18 mg/L), 56.8% in Dornogobi province (F- , 0.04-4.62 mg/L), and 17.4% in Umnugobi province (F- , 0-5.6 mg/ L) exceeded the maximum permissible limit specified in the MNS standard. The analysis revealed that deep well water used as drinking water in the three provinces of the Gobi region falls into multiple mixed composition categories, including hydrocarbonate -sodium, hydrocarbonate-calcium, magnesium, sulfate-sodium, calcium, chlorine, and sulfate-sodium types. Notably, the hydrocarbonate-sodium (HCO3--Na+) type water was found to have a high fluoride content. Due to the presence of multifidous mineral and rock deposits in the three provinces of the Gobi region, it was determined that the water from deep wells undergoes water-rock interactions, and the chemical composition of the water, especifically the fluoride ion content, depend on the geological formations as well as the chemical composition of rocks of the surrounding environment. Говийн бүсийн гүний худгийн усны фторын ионы судалгаа Бид энэ удаагийн судалгаагаар говийн бүсийн гүний худгийн усны фторын ионы агуулгыг тодорхойлж, стандарттай харьцуулан дүгнэлт өгөх, гарал үүслийг тодорхойлох зорилгоор энэхүү ажлыг хийж гүйцэтгэв. Энэхүү судалгаанд Дундговь, Дорноговь, Өмнөговь аймгуудын 144 гүний худгийн усны физик-химийн үзүүлэлт, фторын ионы агуулгыг Монгол улсад мөрдөгдөж байгаа ундны усны MNS 0900:2018 стандарт шаардлагатай харьцуулан тодорхойлсон болно. Судалгаанд хамрагдсан гүний худгийн ус нь саармагаас шүлтлэг орчинтой, маш зөөлнөөс маш хатуу усны ангилалд хамаарагдаж байгаа бөгөөд фторын ионы агуулгаараа 63.2% ундны усны стандарт MNS 0900:2018 шаардлага хангахгүй байгааг тодорхойлов. Үүнээс Дундговь аймгийн гүний худгийн усанд (F- 0.7-7.18 мг/л) буюу 64.8%, Дорноговь аймгийн гүний худгуудын усанд (F - 0.04-4.62 мг/л) буюу 56.8%, Өмнөговь аймгийн худгийн усанд (F- 0-5.6 мг/л) буюу 17.4% нь тус тус MNS стандартын зөвшөөрөгдөх дээд агууламжаас хэтэрсэн байна. Мөн говийн бүсийн 3 аймгийн унданд хэрэглэж буй гүний худгийн ус нь гидрокарбонат-натри, гидрокарбонат-кальци, магни, сульфат-натри, кальци, хлор, сульфат-натрийн төрлийн холимог найрлагатай усны ангилалд хамаарагдаж байгаа бөгөөд HCO3- -Na+ төрлийн усанд фтор өндөр агуулгатай байгааг тодорхойлов. Говийн бүсийн 3 аймаг эрдэс, чулуулгийн орд ихтэйн улмаас гүний худгуудын ус нь ус, чулуулгийн харилцан үйлчлэлд орж усны химийн найрлага, фторын ионы агуулга тухайн орчны геологийн тогтоц болон чулуулгаас хамаарч байгааг тогтоов. Түлхүүр үг: газрын доорх ус, химийн найрлага, гүний худаг, фтор
... However, prolonged exposure to excessive fluoride can result in a range of health issues, including Alzheimer's disease, renal disorders, gastric cancer, and skeletal diseases [4,6,8]. Fluoride contamination has severely threatened several nations, placing over 200 million people globally at risk of fluoride toxicity [9,10]. To ensure human health, the U.S. Environmental Protection Agency (EPA) recommends that the fluoride concentration in drinking water does not exceed 2 ppm [8,11]. ...
A novel fluoride ion fluorescent probe is designed by introducing the strong electron-withdrawing triazine groups into the triarylboron/acridine conjugation system. The A-D-A′ molecular configuration endows this molecule with multiple charge-transfer channels; upon reaction with F⁻, the triazine groups act as primary acceptors within the molecule, facilitating charge transfer between the acridine units and the triazine groups. During fluoride ion detection, changes in the triarylboron moiety lead to a significant bathochromic-shift in fluorescence emission from green to yellow. Theoretical calculations attribute this phenomenon to a reduction in the molecular S1 state energy level upon fluorination, resulting in a pronounced visible color change and chromogenic response during detection. Based on fluorescence intensity changes with varying degrees of F⁻ coordination, a detection limit as low as 10⁻⁷ M was determined for TB-1DMAc-2TRZ, demonstrating the high sensitivity of this probe.
... Nitrate (NO₃ − ) contamination, mainly from agricultural runoff, poses health risks like methemoglobinemia, particularly in infants (WHO 2017). Fluoride (F − ) concentrations over 1.5 mg/L cause dental and skeletal fluorosis (Ayoob and Gupta 2006). Potassium (K + ), though essential, is generally found in low concentrations, with higher levels often indicating pollution (Ravikumar and Somashekar 2017), while sodium (Na + ), influenced by saltwater intrusion and fertilizers, can affect the taste and be unsuitable for sodium-restricted diets if over 200 mg/L (WHO 2017). ...
... Fluoride poisoning is serious in some regions of Morocco and represents a real public health problem [27,28]. Since then, research has been directed to finding an economically feasible method of fluoride removal for regions that have a high concentration of fluoride in their water supplies [29][30][31][32][33]. ...
In this study, we are interested in the elimination of fluoride ions in a batch and dynamic reactor by adsorption on fly ash from the Jorf-Lasfar thermal power plant in El Jadida, Morocco. Indeed, the results obtained showed that the fly ash made it possible to have treated water meeting international standards for fluorides and certain metals such as Pb and Fe; they will undergo a combined treatment. The elimination efficiency increases with the mass of the adsorbent and the stirring speed, with the pH values in a basic medium (7 < pH < 9.5), and this is for a treatment at room temperature. Additionally, it was concluded that fly ash can be used for fluoride removal in waters with high fluoride concentrations. The results obtained in a dynamic reactor have shown that a fluoride elimination percentage of 97% can be reached under the optimal conditions of our experiment. According to its encouraging results by the simplicity proper to the work, the reasonable cost of the works and the equipment and the good efficiency of elimination, it can be foreseen that the fly ash can be used as a filterable adsorbent in the field of water defluoridation.
... While F is considered a micronutrient for humans and drinking water is the primary source of intake, concentrations higher than 1.5 mg L −1 (WHO permissible limit) can lead to health issues such as acute or chronic dental and skeletal fluorosis (WHO 2004). About 95% of ingested F accumulates in teeth and bones (Cerklewski 1997) and can also cause neural and renal disorders, including myopathy (Ayoob and Gupta 2006;Brindha and Elango 2011;Fawell et al. 2013). Dental fluorosis affects teeth, causing discoloration and pitting, while skeletal fluorosis affects bones and joints, leading to pain and limited mobility. ...
Groundwater (GW), which accounts for 97% of the world’s freshwater, is vital for sustaining ecosystems and providing drinking water for millions. However, fluoride (F) contamination in GW poses a significant environmental and public health issue globally. This chapter talks about these important issues and looks at both natural and industrial sources of pollution. It talks about how minerals like fluorite, apatite, cryolite, and amphibole are weathered and used in industries like making bricks and ceramics, smelting aluminum, burning fossil fuels, and making phosphate fertilizer. Factors such as climate change, sedimentary formations, arid regions, and seawater intrusion further exacerbate F levels in GW. High concentrations of F in GW led to severe health risks, including dental and skeletal fluorosis, cognitive impairment, and kidney and thyroid dysfunction. Additionally, F contamination disrupts ecosystems and biodiversity by affecting plants and aquatic life. To mitigate these risks and restore water quality, the chapter discusses various strategies, including natural attenuation, myco-phyco-phyto remediation, membrane filtration, ion exchange, precipitation, and adsorption using materials like activated alumina and biochar. This synthesis of scientific research and practical interventions emphasizes biotechnological approaches and underscores the importance of interdisciplinary collaboration involving fields such as environmental science, public health, and engineering. Effective mitigation measures are essential to protect human health and ensure environmental sustainability. The chapter highlights the need for continued research, proactive management, and policy development to address F contamination in GW comprehensively.
... The non-adsorptive retention process involves precipitation, trapping, caking, and straining, which depend on soil properties such as texture, compaction, porosity, temperature, and wetness, as well as the density and size of the contaminant. Fluoride is not easily transported from the soil due to its strong association with soil components (Ayoob and Gupta 2006). Instead, it is commonly found in soils precipitated into minerals or adsorbed to clays and oxy-hydroxides. ...
Fluoride is necessary for maintaining dental and skeletal health at low concentrations. However, exposure to excessive amounts can lead to fluorosis. On the other hand, the carbon-fluoride (C-F) bond is powerful and persistent, making most fluorocarbons stable, non-corrosive, and reactive. Due to these properties, fluo-rinated compounds (FCs) are used in various industrial production processes and are present in many products we use daily. Before 1966, the potential effects of FCs on the environment and human health were not well-studied. However, that year, fluoride was discovered in human sera, and most fluorocarbons and their daughter compounds were linked to a high threat to human health. The FCs in human sera were later traced back to the environmental aspects of air, water, and soil. This prompted researchers to focus on studying fluoride contamination behaviour in various matrices, including soil and groundwater. This chapter discusses the mobility behaviour of fluoride and fluorocarbons in the soil profile and the fundamental mechanisms that govern their transport and fate. A thorough comprehension of the mobility mechanisms of fluoride and fluorocarbons in the soil profile is crucial to evaluate their possible risks accurately. This involves providing insight into physical, chemical, and biological factors affecting fluoride and fluorocarbons movement and environmental interactions. With this knowledge, we can determine fluoride and fluorocarbon's likelihood of migrating into groundwater and their probable impact on ecosystems and human health. An inclusive understanding of these mechanisms is essential for developing effective risk mitigation strategies for fluoride and fluorocarbons in the soil profile and groundwater.
... Although water can be accessed from various sources, its surface chemical composition is a major factor in determining its suitability. Groundwater is the freshest form of water on earth (Ayoob 2006) and also the most preferable source which covers almost 80% of total domestic requirements (Maity 2018). Even though it is relatively safeguarded from contamination compared to other sources of water, natural processes such as geogenic contamination, along with rising industrialization has rendered groundwater unsafe for drinking. ...
Rapid development of human civilization with increase in human population has contributed to the accumulation of hazardous pollutants in the environment. Fluorine a highly reactive element, is ubiquitously found in the world environment, mostly as inorganic compounds of fluoride. Fluoride is beneficial in trace amounts to the human body, but is extremely toxic beyond threshold limits of 1–1.5 mg/L in drinking water, as established by health organizations. Unfortunately, due to modern industrial activities, agricultural technologies, domestic facilities and rampant urbanization, its presence in all components of the ecosystem has increased to alarming levels. With the contamination of soil, water and air, its effects on plants and humans are extremely adverse. Several damaging effects on the physical and biochemical processes of plants and animals have been documented, the most common being dental and skeletal fluorosis in humans. Asian and African countries are the most affected, with India and China enumerating 66 million and 45 million people suffering from fluorosis respectively. Defluoridation is the attenuation or removal of fluoride from water, deeming it safe for consumption. In the past, various physiochemical and electrochemical methods for remediation or removal of fluoride from contaminated samples have been successfully applied. However, most of these methods requiring sophisticated equipment, laborious procedures, expensive construction and time, proved to be impractical and universally inapplicable. In the past few decades, the role of microorganisms in bioremediation ignited hope in their ability to defluoridate water as well. In this chapter, we provide a comprehensive understanding of the biological means of defluoridation, including the use of microorganisms for bioremediation approaches of biosorption and bioaccumulation to attenuate environmental pollutants. The role of microbial immobilization for defluoridation, metabolic engineering and omics approach for improvements in fluoride-resistant microbes, have been illustrated. This chapter documents the various findings of microorganisms, their consortia, defluoridation rates and mechanisms involved in bioremediation of fluoride. We present the current challenges faced in defluoridation and bioremediation of environmental pollutants, along with some future perspectives.
... Symptoms of dental and skeletal fluorosis have been reported in these areas (S. Kumar et al., 2019;Kumari and Misra, 2023a): these symptoms can arise from chronic exposure to elevated levels of F − through drinking water (Ayoob and Gupta, 2006;Srivastava and Flora, 2020;Veneri et al., 2023;Zhou et al., 2023). The source of F − in contaminated regions of Bihar is thought to be geogenic, being particularly associated with granite gneiss hydrogeological settings (Kumar et al., 2018b). ...
The fluoride-contaminated soil underwent various analyses, including NMR (19F, 27Al, 29Si), thermal analysis (TG-DSC and CP), ATR-IR, and UV-Vis-NIR spectrum. A fluoride meter measured the fluoride ion in the acid and alkali-treated soil filtrate. Entropy was calculated for the original, acid and alkali-treated soil. The calculated entropy of all three soil types is approximately 7.45 . The results showed that the maximum CP of the acid-treated soil at ~310K, 2.37 is higher than that of the original soil at ~326K, 2.11 . This is due to increased hydrated molecules and decreased fluoride compounds in the acid-treated soil. According to NMR analysis, the composition of all the examined soil is similar to various ZSM-5F, HY, H-ZSM-5/ NH4-ZSM-5 FLD, C3A/ C12A7, AlOyN4-y(0≤y≤4), and AHFS washed ZSM-5 zeolite types. It was found that treating the soil with acid followed by thudding filtrate with alkali is more effective in removing the presence of fluoride in the filtrate. After filtering the precipitate, the fluoride ion is reduced from 266 ppm at pH 11.08 to ~2.0 ppm at 7.08 pH. It is also found that the fluoride ion is suppressed as fluoride compounds, {NaF, NH4F, (NaF)n, and NaHF2}, through the use of an ammonia solution.
Fluoride related health issues such as dental and skeletal fluorosis have become a global concern in recent times. Adsorption is one of the affordable defluoridation techniques. This study reports the potentiometric determination of fluoride adsorbed onto Aluminium modified zeolite Na-LSX (AMZL) from aqueous solution at 25oC and various experimental conditions: pH (4.5-9), initial fluoride concentrations (3-15 mg/L), adsorbent dosage (2.5-12.5 g/L) and contact time (4-6 days) in a batch system. The obtained adsorption data was fitted to Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms. Error functions, χ2, SSE, SAE were used in conjunction with R2 to ascertain the best fitted isotherm. The various kinetic models Lagergren’s pseudo-first-order, Ho’s pseudo-second-order, Intra-particle Diffusion and Elovich models were used to evaluate the kinetics of fluoride adsorption. The maximum fluoride uptake unto AMZL occurred at pH 5.5 over a period of 360 min. An increase in adsorbent dosage and pH affected fluoride removal. The presence of bicarbonate ions had a negative effect on the adsorption of fluoride however, chloride and nitrate did not affect the adsorption of fluoride. By the use of error functions, χ2, SSE, SAE and the coefficient of regression, R2 values, Langmuir isotherm model gave the best description of fluoride adsorption onto AMZL. The maximum fluoride adsorption capacity of AMZL based on Langmuir model was found to be 4.122 mg/g. The Ho’s pseudo-second order kinetics best fitted the fluoride adsorption data obtained. The adsorption mechanism was found to be predominantly physisorption than chemisorption.
A facile method was employed to impregnate activated carbon, a commonly used water treatment medium, with nanostructured magnesium oxide for fluoride removal. Batch adsorption tests were conducted to evaluate the adsorption performance of the nanostructured magnesia-impregnated activated carbon (nMgO@AC) for fluoride removal. The results demonstrated that this composite material exhibited a good adsorption capacity, with a maximum equilibrium uptake of approximately 121.1 mg/g for fluoride. Kinetic studies revealed that the adsorption process followed the pseudo-second-order adsorption kinetic model, reaching equilibrium in about 100 min. Within the initial pH range of 3 to 11, the adsorption efficiency of nMgO@AC for fluoride remained above 95%, indicating that the initial solution pH had a minimal effect on the material’s fluoride removal capability. The adsorption mechanism was elucidated by characterizing the material properties before and after adsorption using SEM, TEM, XRD and XPS. Initially, magnesium oxide reacted with water and rapidly transformed into magnesium hydroxide. Subsequently, a ligand exchange occurred between the hydroxide groups in magnesium hydroxide and fluoride ions in the aqueous solution, resulting in the effective removal of fluoride. The findings of this study suggest that nanostructured magnesia-impregnated activated carbon holds significant potential for the treatment of fluoride-containing wastewater, particularly for highly alkaline wastewater.
Food chain contamination by toxic elements such as arsenic (As) and fluoride (F) has emerged as a significant global public health issue. Both elements are naturally occurring in the environment, but their presence in the food chain has been exacerbated by anthropogenic activities such as mining, industrial processes, and the use of contaminated water for irrigation. Chronic exposure to arsenic and fluoride through contaminated food and water can lead to severe health consequences, including cancer, neurological disorders, and skeletal fluorosis. This paper provides an overview of the sources, pathways, and health impacts of arsenic and fluoride contamination in the food chain, along with mitigation strategies.
Fluoride ion possessing substantial biological importance demands widespread applications on the basis of physiological and detrimental effects on human body and environmental aspects. Therefore, attractive attention has been paid by the researchers to reach the utmost stage of development of versatile colorimetric and fluorometric fluoride ion sensors. For this purpose, proton transfer phenomenon is an excellent pathway to trigger the recognition of fluoride ion using various kinds of sensor molecules. A strong mode of binding interaction between the chemosensor and F ⁻ ion was streamlined in terms of colorimetry, fluorometry and NMR‐ and DFT‐based theoretical studies. This minireview article summarizes the recent development of various fluoride sensors based upon the proton transfer–mediated signalling mechanisms, namely, hydrogen bonding–promoted proton transfer, excited state intermolecular proton transfer (ESPT) and excited state intramolecular proton transfer (ESIPT).
Fluoride (F⁻) toxicity has become a significant environmental and public health concern globally. Microbial defluoridation offers a promising approach to restoring soil health, increasing crop yields, and minimizing fluoride bioaccumulation in the food chain. In the present experiment, seven bacteria with varied levels of fluoride resistance were screened out in vitro using tryptone soya agar medium supplemented with different grades of Sodium Fluoride (NaF) from the composite topsoil (0–0.2 m depth) of fluoride-rich rice fields of three blocks (Arsha, Jhalda-I, and Joypur) of the Purulia district, West Bengal, India. Using NCBI- BLAST and 16S rDNA barcode sequence-based molecular phylogeny, the seven isolates were identified as Aeromonas aquatica strain KPNA_FR1 (GenBank Acc. PP957426), Bacillus pumilus strain KPNA_FR2 (GenBank Acc. PP948725), Enterobacter sp. Strain KPNA_FR3 (GenBank Acc. PP948726), Enterobacter ludwigii strain KPNA_FR4 (GenBank Acc. PP948727), Priestia aryabhattai strain KPNA_FR5 (GenBank Acc. PP948728) Enterobacter sp. strain KPNA_FR6 (GenBank Acc. PP948729), Bacillus pumilus strain and KPNA_FR7 (GenBank Acc. PP948730). Out of these seven isolates, the most Fluoride tolerant bacterium Enterobacter ludwigii strain KPNA_FR4 can tolerate a maximum of 11,250 ppm NaF in vitro and exhibited ~ 78% defluoridation capacity from medium. The plant growth-promoting efficiency of KPNA_FR4 including other isolates concerning the solubilzation of phosphate (123.67 ± 13.41 ppm), potassium (2.49 ± 0.10 ppm) and zinc (50.80 ± 5.38 ppm) have also been reported. Thus, the isolated fluoride-resistant bacteria, having significant potential as fluoride bioremediator and biofertilizers, may be used to mitigate soil fluoride toxicity sustainably and to increase agricultural productivity as well.
Jeera River of Bargarh District, Odisha faces serious deterioration due to massive human intervention. It is particularly susceptible to degradation because it receives industrial and waste water emissions from surrounding organizations and municipal bodies. The river was formerly a flourishing tributary of the massive Mahanadi River that possessed excellent navigability, an array of aquatic ecosystems, and a well-established basin with an expanding agricultural sector. The current condition of the Jeera River is deplorable, leaving behind only minimal economic and ecological values. The study emphasizes analyzing the seasonal variation of the water quality rating of Jeera River in terms of the Water Quality Index (WQI). WAWQI (Weighed Arithmetic Water Quality Index) values show that almost all sampling sites have poor or unsuitable quality. During the monsoon season, the water quality deteriorated the most, with an average WQI score of 516.430 compared to pre- and post-monsoon with average WQI values of 154.558 and 276.014 respectively. CCMEWQI (Canadian Council of Ministers of Environment Water Quality Index) values indicate that water quality ranges from marginal, and poor to fair. This study concludes that out of the eight sampling sites, station 5 (Dumerpali) is observed to be the most polluted site. Many water quality parameters including iron, turbidity, nitrate, phosphate, E. coli, and Total coliform are found to exceed the permissible limits prescribed by WHO and BIS. Reducing sewage outflow, blocking direct stormwater discharge, and avoiding continuous solid garbage disposal by neighbouring populations are ways to improve river water quality.
Graphical abstract
This book chapter presents a comprehensive analysis of the controversial topic surrounding water fluoridation and its potential link to cancer risk. The longstanding debate over the merits and drawbacks of water fluoridation has sparked discussions on its impact on dental health, while also raising concerns about the possible association with cancer development. Through a meticulous examination of scientific literature, this chapter scrutinizes the epidemiological evidence pertaining to the correlation between water fluoridation and cancer incidence. It critically assesses research studies that either support or challenge the notion that exposure to fluoride in drinking water may elevate the likelihood of cancer occurrence. Moreover, this chapter delves into the biological mechanisms underlying the potential carcinogenic properties of fluoride within the human body. It explores the intricate pathways through which fluoride may influence the initiation and progression of cancer, elucidating the molecular processes at play. The overarching objective of this chapter is to furnish a nuanced and informative portrayal of the existing knowledge base on water fluoridation and cancer risk. By synthesizing and evaluating available evidence, it aims to enrich the discourse on this intricate public health issue, fostering a deeper understanding of its complexities.
Fluoride toxicity, resulting from prolonged exposure to elevated fluoride levels leading to oxidative stress, poses significant health risks, affecting various bodily systems and cellular processes. It also upregulates hormonal mechanisms, causing hormonal disruption in exposed individuals. Extracellular matrix degradation and bone deformity are expected impacts of fluoride toxicity, which are executed by elevated levels of Cyt c, Beclin 1, calcium, and Nf-kB. Due to the excessive release of calcium ions in the cytosol, it was depleted from its natural reservoir in the body, like teeth and bone, which finally leads to dental fluorosis, enamel hypo mineralization, weakening tooth structure, and susceptibility to decay. Skeletal fluorosis was also found commonly in fluoride-exposed individuals, which finally leads to bone and joint abnormalities. Fluoride also hampers ATP formation by interfering with glycolysis pathways, and it alters metabolic and reproductive hormones, causing impaired spermatogenesis, reduced sperm quality, and infertility. Hepatic effects manifest as hepatocyte degeneration and necrosis, contributing to liver damage. Developmental effects include genetic damage to DNA, IQ deficits, and increased risk of developmental abnormalities. Neurological impacts involve structural changes in the brain, memory issues, and neuronal loss. In this way, it was evident that Fluoride toxicity affects cellular organelles, inducing oxidative stress, apoptosis, and disrupting hormonal balance, mediated through alterations in cellular signaling pathways, transcription factors, and protein synthesis. It alters different genes implicated in bone metabolism, hormone signaling, and immune function, which leads to harmful impacts of fluoride on human health.
The results of the analysis of F and other trace elements (As, V, Cr, Ni, Cu, Zn, Se, Mo, Ag, Cd, Sn, Sb, Hg, Pb, Li) of natural waters (18 sites — surface waters of the White Tisza rivers, Yew, streams, springs, Lake Brebeneskul and well water) of the Rakhiv district of Transcarpathia region, statistical indicators were calculated (the median content was taken as background). In most samples, the concentration of fluorine ranges from 0.014 to 0.44 mg/dm3 (the background content is set at 0.076 mg/dm3, the maximum permissible concentration (MPC) is 1.5 mg/dm3). The content of fluorine in the waters of different altitude zones (low-mountain, mid-mountain, mountain, sub-alpine and alpine) was analyzed — no dependence was found. Correlation analysis showed an average positive relationship between fluorine and arsenic (the background content of As was determined to be 0.00009 mg/dm3, the MPC was 0.05 mg/dm3). For a comparative analysis of the content of F and As in the waters, the concentration coefficient was calculated (Kс — the ratio of the element in the water to the background content). It was found that in the well waters of the sanatorium “Hirska Tysa” (used for baths) Kс As — 3277, Water “Health Falls” Ks As — 30, with Kс F less than 1. Water samples where Kс F and As are increased were also found: stream of the Krasne Plesso tract — Kс As —11, Kс —F of the Shchaul stream — 2; Kс As — 22, Kс F — 2. Analysis of the fluorine content in bottled water (17 names) sold in Ukraine showed that the optimal content (0.7—1.2 mg/dm3) in deep artesian waters is Rohansk , Zhytomyr springs, Water V7, which can be recommended to the population to replenish the fluoride balance of the population of the region.
Many minerals and rocks contain fluoride, a common element that has caused significant concerns due to its extensive distribution and high concentration in groundwater. Naturally occurring in soil and water, fluoride (F−), an anion of fluorine, acts as a harmful inorganic pollutant even at lower concentrations and requires rapid treatment. Although expensive, time-consuming, and labour-intensive, conventional fluoride remediation techniques are not viable for sustainable agriculture. The answer is to eradicate this environmental pollution as much as possible by implementing contemporary, economical, eco-friendly, and cost-effective technology. biological techniques, such as bioremediation, which uses higher plants, fungi, bacteria, and algae, provide promise for managing fluoride pollution, recovering polluted soil, and enhancing vegetation. Native natural agents may be more effective in sustainable agriculture and preferred over hazardous chemicals. The current article examines several bioremediation strategies intended for fluoride-contaminated habitats and evaluates their possible implications for environmental management.
Fluorosis affects around 70 million people worldwide but remains a neglected public health concern. Countries like China, India, and Pakistan reported high fluoride levels of naturally occurring fluoride in their water. Other sources of high fluoride concentration in the environment are from using F-enriched fertilizer and the chemical processing of phosphorus and other industrial activities such as using Fluorine-based compounds. Therefore, this chapter focuses on the mobility of fluorine in the environment, its distribution, and associated health risk assessment. We also discussed the impact of fluorine on humans and animals as well as the gene expression of different cell types exposed to high levels of fluoride. Consequently, research is concentrated primarily on finding ways to lower the fluoride content in environments, mainly water and soil. Many methods have been developed to reduce or eliminate fluoride concentrations in the environment or remove it from drinking water. Among the most often employed techniques are ion exchange, coagulation, precipitation, and adsorption. Nevertheless, substantial drawbacks include high operating costs, complex maintenance schedules, and sludge disposal requirements. Thus, simple, affordable, and applicable methods to an array of conditions are beneficial. The conditions mentioned above can be met with the use of adsorption strategies. Industrial waste products, biogenic adsorbents, and alumina are a few often utilized adsorbents for fluoride removal. Here, we covered some of the best economical, eco-friendly, and effective bio-adsorbents, along with their features. Despite reports of some adsorbents having exceptional fluoride removal capabilities, additional innovative adsorbents with both technological and commercial benefits are urgently required to be developed.
Fluorinated compounds are utilized in several industrial processes and mining activities where they find their way into wastewater and sludge from municipal wastewater treatment plants. The presence of these compounds in wastewater streams poses significant environmental and health risks that should not be underestimated due to their high resistance to biological and chemical degradation. Various techniques, such as nanofiltration, ion exchange, chemical precipitation, adsorption, etc., have been employed to remove these pollutants from waste water, but limitations identified with these methods cannot be overlooked. Microorganisms offers an alternative approach in the elimination of fluoride from wastewater due to their cell wall composition contain amines, carboxylates, and phosphate. The various enzymatic mechanisms utilized by microorganisms in the removal of fluorinated compounds from wastewater are discussed. The application of microalgal-bacterial systems in fluorine removal and the importance of mitigating fluorine pollution in wastewater is also highlighted.
Fluoride and fluorocarbons find their use in consumer products and industrial products. They have raised considerable debates due to their potential toxicity which casts significant health and environmental concerns. Fluorides primarily enter living organisms through dental care products, foods, beverages, and drinking water giving benefits to teeth and bone health. However, excessive intake leads to fluorosis, posing threats to bones and other physiological systems. Fluoride toxicity can be attributed to their interference with enzymatic activities and calcium metabolism. Fluorocarbons including polyfluoroalkyl substances (PFAS) find widespread use in non-stick coatings, fire extinguishants, refrigerants, foam blowing and various other industrial processes owing to their unique physical and chemical properties. Despite their utility, these compounds are persistent and bioaccumulate to exert potential adversities on wildlife and man. Fluorocarbons may disrupt endocrine functions related to cancer, hepatic damage and developmental issues. They are also causing serious environmental problems like stratospheric ozone depletion and global warming that stand out to be the primary concerns about the survival of the human race. Fluoride and fluorocarbon management thus needs a critical review of the risk assessment frameworks, and regulatory measures with more advances in detection techniques, stringent and rigorous monitoring, and mitigation strategies to minimize overexposure. Developing safer alternatives is pivotal to addressing such challenges. Hence a comprehensive understanding is the need of the hour to underscore the balance between their beneficial impact and potential risks, emphasizing the importance of informed policy decisions for protecting human health and the environment.
This study aims to delineate the spatial distribution of nitrate and fluoride in groundwater and to estimate the non-carcinogenic risks using the human health risk assessment model recommended by the United States Environ- mental Protection Agency (USEPA). Forty-two samples were collected from wells and boreholes and analyzed for nitrate, fluoride and other water quality parameters. Results of the study indicate that fluoride and nitrate concentra- tions vary respectively from 0.13 to 9.41 mg·L−1 and from 0.13 to 432.24 mg·L−1 with respective median values of 2.65 and 13.85. About 69% of groundwater samples exceed the allowable limit (1.5 mg·L−1) of fluoride for drinking water. Spatial distribution of fluoride shows high concentrations in certain locali- ties with values ranging from 6.74 mg·L−1 to 9.41 mg·L−1. The spatial distri- bution of nitrate indicates that the majority of water samples (87.18%) have nitrate concentrations lower than the World Health Organization (WHO) standard guideline value of 50 mg·L−1. Assessment of non-carcinogenic risks associated with intake of polluted groundwater in local populations indicates that 82.05% and 87.18% of groundwater samples have a THI > 1 in adults and children, respectively. However, the highest THI value (15.87) was recorded for children suggesting that children face greater non-carcinogenic risks than adults. The results of this study can be used as a support by the policymakers and practitioners to develop appropriate policies for effective and sustainable groundwater management and to monitor human health implications and sustainable groundwater management and to monitor human health implications.
Some of the fundamental questions about the fluoridation of public water supplies are ethical in nature: e.g. Is medication with an uncontrolled dose wrong? Is mass medication, which is either compulsory or expensive to avoid, wrong? Is fluoridation right if its risks are less than its benefits? Some leading proponents of fluoridation attempt to evade such ethical issues by quasi-scientific argument. For instance, they claim that fluoridation is not medication, but merely an 'adjustment' of the natural fluoride concentrations in drinking water to the 'optimal' level for reducing tooth decay. Or they allege that fluoride is an essential nutrient, rather than a medication. But, ethical questions cannot be so easily transformed into scientific and technical ones to be answered glibly by dentists and medical practitioners. This paper assists the elucidation of several ethical questions about fluoridation by first clarifying several related questions of science, technology and logic. This clarification leads to the conclusions that fluoride, at the levels recommended by pro-fluoridationists for reducing tooth decay, is not an essential nutrient; is not a natural substance for babies or for most adults; is not a compulsory medication, but is an expensive-to-avoid medication with an uncontrolled dose; and is harmful to some people. There is scientific evidence that the benefits of fluoridation have been greatly overestimated, bet the actual magnitude of benefits is still unclear. It is now clear that any benefit comes from the action of fluoride on the surface of teeth, but there is negligible benefit from swallowing fluoride. It is net possible to weigh risks against benefits in a value-free manner. These scientific, technical and logical conclusions prepare the way for ethicists and others to examine the fluoridation issue, unencumbered by the usual 'scientific' myths. The original ethical concerns about fluoridation are found to be well-posed questions, an ethical question used by proponents to justify fluoridation is found to be improperly posed, and a new ethical question arises from the analysis.
A Survey was made in fifteen villages of Dungarpur district of Rajasthan for the prevalence of dental and skeletal fluorosis in villagers and their domestic animals. Fluoride concentration (mean) in drinking waters of these villages varied between 1.7 to 6.1 mg/L. An overall 73.0 and 82.9 percent prevalence of dental fluorosis was observed in children (below 18 years age) and adults respectively. Cent percent prevalence of dental fluorosis in children and adults was observed at 5.2 and 3.8 mg/L fluoride concentration respectively. The prevalence of skeletal fluorosis in adults was 32.5 percent and the highest prevalence (60.8%) was observed at 6.1 mg/L flouoride concentration. Male subjects relatively showed higher prevalence of skeletal fluorosis. Out of 1521 cattle and 471 buffaloes, 1007 (66.2%) and 318 (67.5%) showed the evedence of dental flourosis. Cent-percent prevalence of dental fluorosis in calves of both animal species was observed at the above 2.8 mg/L fluoride concentration. The highest prevalence of skeletal fluorosis, 61.6 percent in cattle and 66.6 percent in buffaloes has been observed at 6.0 mg/L fluoride concentration. Simultaneously, 1260 goats and 580 sheeps were also examined for the evidence of fluorosis but not a single case was detected.
A preliminary and systematic study of the chemical composition of monsoon rainwater over Bhopal has been carried out during the years 1977 and 1978. The analytical results reveal that the total minerals of the rainwater is governed by the meteorological and geographical parameters. A definite pattern, however, could not be ascertained and the concentration of different ions vary considerably. Bicarbonate is the predominant anion and calcium is the predominant cation. Most of the ions originate from the non-marine sources, although marine origin is also likely to contribute for the presence of some ions in the rainwater. The presence of trace elements such as strontium, copper, zinc, manganese and iron have been recorded but lithium and nickel could not be detected in the local rainwater samples during the period.
Chronic fluoride intoxication (fluorosis) was observed in villagers and their domestic animals (cattle, buffaloes, sheep and goats) from ten villages of the Udaipur district of Rajasthan where drinking waters contained 0.3 to 7.0 mg/L fluoride. The prevalence of dental fluorosis and skeletal fluorosis in villagers was relatively higher than that observed in the animals. At 5.8 mg/L mean fluoride concentration, 88.7% of children (<18 years) and 100% of adults were found to be affected with dental fluorosis. The highest prevalence (42.2%) of skeletal fluorosis was observed at 5.8 mg F/L (mean). Males showed relatively a higher prevalence of skeletal fluorosis. In general, the prevalence and severeness of skeletal fluorosis increased with increasing of fluoride concentration and with age. None of fluorotic subjects revealed evidence of genu-valgum syndrome and goitre (hyperthyroidism). Among mature animals, buffaloes were found to have a higher prevalence and greater severity of dental and skeletal fluorosis when compared with cattle. The prevalence of dental fluorosis was higher in calves of both type of animals than in adults. Sheep and goats examined at the same time were found to be free of fluorosis. Radiological findings and deformities in fluorotic subjects as well as fluorosis in relation to fluoride concentrations, age and sex have also discussed.
Human diseases associated with excess consumption of fluoride through drinking water and food grains have been observed in many localities in Peddavankahalla basin. Fluorosis is severe in the part of the basin covered by black cotton soil which is under intensive irrigation, comprising six villages. Dental hypoplasia has been noticed in a few villages. We discuss here probable source of fluoride, causes for its concentration and suggest possible remedial measures.
Anomalously high concentration of fluoride (upto 16 ppm) has been observed in dug/tube well water, which is being used for drinking and irrigation purposes, around Palri, Andor and Wan villages, in western part of Sirohi district, Rajasthan. Fluoride concentration in groundwater is much higher than the permissible limit of 0.6-1.5 ppm of fluoride recommended for potable purposes. Water samples with more than 5 ppm fluoride are confined to Andor and Wan villages. Mottling is commonly observed in people of this area with a few cases of crippling fluorosis. Areas with such a high fluoride content require serious attention and remedial measures like setting up of large-scale defluoridation plant, use of simple domestic defluoridation methods and public awareness for preventing harmful diseases like fluorosis.
During a project to determine the fluoride levels of milk in Lake Elementaita region, the authors were astonished by the high levels of fluorosis in children living in the area. With special reference to children, a study was designed to establish and describe the levels of dental fluorosis and also to determine other sources of fluoride to the community. The levels of dental fluorosis were recorded using Thylstrup and Fejerskov classification method (TF) for children aged between 2-14 years. Biodata information, feeding habits and details of fluoride history were collected using a questionnaire form filled out with the help of teachers and/or parents. Results pertain to both continuous and non-continuous residents for both primary and permanent dentition. The high fluorosis level of 95.8% was associated with the fluoride concentration in the community water supply and food. Food samples analysed for fluoride include cows milk (the major source of nutrients for the children in the area), vegetables and water. Fluoride levels in drinking water from different boreholes were high, varying from 2.0-20.9 μg/mL-1. Milk fluoride levels in samples from seven localities ranged from 0.05-0.22 μg/mL-1 (mean) and an individual animal range of 0.02-0.34 μg/g-1. Vegetables had fluoride levels between 7.9-59.3 μg/g-1 with an exception of one with 296.6 μg/g-1. The soils in which the vegetables are grown had over 1000 ppm. This being a landscape formed by the process of faulting and volcanic activity, the dust from Lake Elementaita also had high fluoride concentration of 2300 μg/g-1.
Any use of fluorides, whether systemic or topical, in caries prevention and treatment in children results in ingestion and absorption of fluoride into the blood circulation. The mineralization of teeth under formation may be affected so that dental fluorosis may occur. Dental fluorosis reflects an increasing porosity of the surface and subsurface enamel, causing the enamel to appear opaque. The clinical features represent a continuum of changes ranging from fine white opaque lines running across the tooth on all parts of the enamel to entirely chalky white teeth. In the latter cases, the enamel may be so porous (or hypomineralized) that the outer enamel breaks apart posteruptively and the exposed porous subsurface enamel becomes discolored. These changes can be classified clinically by the TF index to reflect, in an ordinal scale, the histopathological changes associated with dental fluorosis. Compared with Dean's and the TS1F index, we consider the TF index to be more precise. Recent studies on human enamel representing the entire spectrum of dental fluorosis have demonstrated a clear association between increasing TF score and increasing fluoride content of the enamel. So far, no useful data on dose (expressed in mg fluoride/kg b.w.) -response (dental fluorosis) relationships are available. In this paper, we have, therefore, re-evaluated the original data by Dean et al. (1941, 1942), Richards et al. (1967), and Butler et al. (1985) from the USA, by applying the equation of Galagan and Vermillion (1957) which permits the calculation of water intake as a function of temperature. By so doing, it can be demonstrated that there is a linear association between fluoride dose and dental fluorosis (r ² = 0.87). Even with very low fluoride intake from water, a certain level of dental fluorosis will be found in a population. When the linear dose-response curve is applied to previous data from the use of fluoride supplements, these data are in full accordance. This indicates that we already have useful data available which to some extent allows us to predict prevalence and severity of fluorosis in a child population which is exposed to a known amount of fluoride. Because dental fluorosis may occur in some individuals and populations to a higher prevalence and degree than expected, and there exist rare cases who exhibit clinical changes similar to those of fluorosis—but with no known excessive fluoride background—it is concluded that it is important to intensify studies on factors which alone or in combination can make individuals more or less susceptible to the effect of fluoride.
Effect of varying levels of exchangeable sodium percentage (ESP) on the solubility and adsorption of fluorine in a soil was studied in the laboratory. Water-extractable F of 25 differentially gypsum treated and uniformally cropped field plots increased linearly with increase in soil ESP (r = 0.93) and pH (r = 0.95). Incubation studies revealed that a major portion of the added F was immobilized within the 1st 8 days. A relatively lesser quantity of added F was immobilized in soil of higher ESP and pH. Fluorine adsorption by these soils was describeable by Langmuir isotherm up to an equilibrium soluble-F concentration of 0.6 mmol/liter. Beyond this limit the adsorption pattern seemed to reflect immobilization through precipitation. At any equilibrium soluble F concentration, there was a decrease in adsorption of F with increase in soil ESP or pH. Addition of amendments, like gypsum, to these soils which reduce ESP and pH will also simultaneously result in a reduction of water-extractable F.
This is a review of findings on workers in an aluminum plant with industrial fluorosis. Early signs of the disease are nocturnal back pains and restriction of the rotation of the trunk. Stage I of the disease usually occurs after 10 yr, stage II after 15 yr and stage III after 20 yr. The diagnosis was established at an early stage through biopsies of the iliac crest by histological and microanalytical determinations of fluoride. A fluoride level exceeding 4000 ppm in the iliac crest ash was found to be associated with typical signs of fluorosis. The early histological changes including the microradiographic findings and typical foci of calcification in the corticalis are demonstrated. Three necropsies in patients with fluorosis at different stages are reviewed. One of them showed a lesion in the cells of the anterior horn of the spinal cord which was believed to be related to fluorine. Cristallographic studies revealed that crystals of fluorotic bone mineral had become more slender. Increase in gastric acidity was associated with greater sensitivity toward fluoride. Prophylaxis and treatment of industrial fluorosis are discussed. (60 references)
Studies on 5 patients with gross symptoms and signs of fluorosis provided evidence that hyperactivity of the parathyroid glands is a frequent consequence of skeletal fluorosis. The plasma IPTH levels were elevated in all cases and one patient exhibited an adenoma and hyperplasia of the parathyroid glands at surgery. The hyperactivity of the parathyroid glands in skeletal fluorosis in the presence of decreased solubility of the bone mineral (fluoroapatite) strongly suggests that it is a compensatory attempt to maintain a normal extracellular ionized calcium equilibrium. The possible mechanism responsible for hyperfunction of the parathyroid glands is discussed.
Adsorption and leaching of fluoride in typical Chinese soils in relation to physical and chemical parameters of the soils were studied. F-adsorbing capacity of soil can be ranked as Black soil > Purplish soil > Red earth > Dark brown earth > Drab soil > Sierozen. Leaching rate from different soils was Drab soil > Sierozen > Black soil > Purplish soil > Red earth > Dark brown earth. The adsorption of Fin soils decreased from humid areas to arid areas and from acidic soils to alkaline soils. The smaller loss of F leaching occurred from acid soil in tropical humid areas and in temperate semi-humid areas compared with arid areas. This would result in enrichment of fluoride in shallow groundwater in northern China.
Ribs, metacarpal, and metatarsal bones were obtained from cows subjected to excessive fluoride ingestion and examined for fluorine, citric acid, calcium, and phosphorus content, and alkaline phosphatase activity. The fluorine content increased approximately 10- to 20-fold over the controls, the increase being greater in the periosteal zones of the bones than in the endosteal zones. The alkaline phosphatase activity exhibited a 3.58 to 6.92 fold increase in the osteofluorotic bone, and the activity generally closely correlated with the fluorine concentrations of the bone. The citric acid concentration in bones showed a wide range variation; however, no significant changes were observed with the citric acid calculated on an average base between normal and osteofluorotic bones. Bone calcium was somewhat higher and phosphorus level lower in the bones from the cows with osteofluorosis.
No significant alteration of function of the thyroid gland was observed in cases of fluorosis. Definite changes in the parathyroid status have been noted in a few patients. The mechanism is not precisely understood but it is related to the initial osteomalacia like picture produced by fluoride ions in combination with calcium deficiencies. These changes constitute a compensatory homeostatic mechanism. These preliminary observations call for further elaboration.
Dental data collected for virtually all New Zealand children, as well as comprehensive data from other countries, indicate no dental benefit from water fluoridation. Claims for a benefit depend on small-scale studies of selected samples of children. The classic fluoridation research is critically re-examined.
Results are reported of a comprehensive investigation into fluoride levels in drinking water and other environmental characteristics, and their relation to endemic fluorosis, in Hohhot Region, Inner Mongolia.
This paper represents an extension of a previous study concerned with the incidence of cancer in the steel city of Ontario. A review of the mortality rates for cancer for the years 1966 to 1970 in Hamilton reveals a considerably higher death rate from cancer in Hamilton than in the less industrialized city of Ottawa. The highest rate (65 per 100,000) occurred in the proximity of the steel mills, compared with the death rates (23 and 12 per 100,000) farther distant. Admission records at two large Hamilton hospitals showed a close correlation between respiratory disease and the daily pollution indices. The role of fluoride, as a major pollutant derived from the manufacture of steel, is discussed.
Further study was made of the estimated population of 50,760 using well water high in arsenic and fluoride in the area of Kuitun, in China, by examining, for arsenism and fluorosis, over 3,500 residents using water from seven wells. Arsenic and fluoride were seen to be able to exert toxic effects independently when present in well water at levels of 0.12 mg/L or more of arsenic and 0.2 mg/L or more of fluoride. As the level of arsenic increased from 0.12 to 0.6 mg/L the incubation period for arsenism decreased from 10 to 0.6 years and the prevalence at 10 years increased from 1.4 to 47%. Improvement occurred in 82% and the development of new cases was prevented one year after the quality of the water was improved.
Data from dental examinations of 39,207 schoolchildren, aged 5-17, in 84 areas throughout the United States are analyzed. Of these areas, 27 had been fluoridated for 17 years or more (F), 30 had never been fluoridated (NF), and 27 had been only partially fluoridated or fluoridated for less than 17 years (PF). No statistically significant differences were found in the decay rates of permanent teeth or the percentages of decay-free children in the F, NF and PF areas. However, among 5-year-olds, the decay rates of deciduous teeth were significantly lower in F than in NF areas.
Radiographs of 80 patients with severe endemic fluorosis of coal-burning type [CBEF]-49 males and 31 females aged 30 to 70 years-were analysed to examine the changes to the bone substance, peripheral structure of bone, and joints. The changes to bone substance were: 1) osteosclerosis type, 62 cases (77.5%); 2) mixed type, 16 cases (21.25%); 3) osteoporosis type, one case (1.25%); 4) osteomalacia type, one case (1.25%). The changes to the joints were: articular lesions were found in the hips and elbows in 79 cases (98.75%), and in the knees in 75 cases (93.75%). When combinations of the above three changes occur, the classification of the disease is according to the most severe one of the three. Our findings can increase the accuracy of X-ray diagnosis, making it more consistent with clinical diagnosis, thus improving prevention and treatment of CBEF.
The mechanisms by which fluoride acts in caries prevention and in the therapy of osteoporosis can be understood only in the light of the pharmacokinetic behavior of fluoride. More detailed studies of the dynamics of fluoride absorption, distribution, retention in hard tissues, and excretion in urine, saliva and sweat are now possible, since modern and more sensitive techniques of F− analysis have become available, e.g. F−-specific electrometry and gas chromatography. They provide a continuous follow-up of F− levels in body fluids. The concentrations of free F− ions in plasma and saliva of man, and the rate and duration of F− elevation in these body fluids following fluoride uptake and absorption are of special importance with regard to the availability of fluoride for the calcified tissues. Therefore, we evaluated fluoride levels in human plasma and saliva during 24-h periods under controlled dietary conditions.
Leachable fluoride absorbed in the soil and clays are the main sources of fluoride in groundwater. A good correlation between F- and Na+ (lithogenic sodium) have been obtained. Alkalinity of the circulating waters may be one of the deciding factors for the high incidence of fluoride in natural waters in Amreli district. -Authors
This comprehensive epidemiological study - performed during the period 1963-1993 on 0.4003 million children residing in non-endemic (F- ≤ 1.0 ppm) and endemic (F- > 1.0 ppm) fluorosis villages of India - was designed to investigate the essentiality or otherwise of fluoride and calcium nutrition in the prevention and control of dental caries. In non-endemic areas, of the children with adequate calcium nutrition, 7 percent showed dental fluorosis and 2 percent had dental caries, while of children with inadequate calcium nutrition 14.2 percent showed dental fluorosis and 31.4 percent had dental caries. In endemic areas, of the children with adequate calcium intakes, 59 percent had dental fluorosis and 10 percent had dental caries, while in the calcium-inadequate group, 100 percent exhibited dental fluorosis and 74 percent had dental caries. Our findings indicate that dental caries was caused by high fluoride and low dietary calcium intakes, separately and through their interactions. Dental caries was most severe and complex in calcium-deficient children exposed to high intakes of endemic fluoride in drinking water. The only practical and effective public health measure for the prevention and control of dental caries is the limitation of the fluoride content of drinking water to < 0.5 ppm, and adequate calcium nutrition (dietary calcium > 1 g/day). The World Health Organisation policy and recommendations on fluorides are not universally acceptable, especially for the environment of developing countries, with nutritional deficiencies, endemic fluorosis, and different caries prevalence trends. In the light of our scientific data, WHO recommendations require modifications to achieve dental health for all by the year AD 2000.
The relation between fluoride naturally in drinking water, mottled enamel and dental caries in children is analyzed. The prevalence of mottled enamel (dental fluorosis) in children of 73 communities with drinking water containing 0.4-6.6 ppm (parts per million) F- is log-normally distributed with the concentration of natural fluoride in drinking water. Signs of intoxication may be anticipated at levels below 1 ppm F-; at 0.4 ppm F-, approximately 3% of the children, on the average, show dental fluorosis. The prevalence of dental caries in children aged 12 to 14 from 136 communities with drinking water containing 0.15-5.8 ppm F- shows no relationship with the concentration of fluoride naturally in drinking water. It can be concluded from these results that at the so-called 'caries prophylactic level' of fluoride (1 ppm) some signs of intoxication must be expected but no caries prophylactic effect.
Data indicating a more rapid increase in cancer death rate in fluoridated than in nonfluoridated cities were analyzed to determine to what extent the net increase observed in fluoridated cities could be attributed to age, race, or sex. Between 1952 and 1969, no significant fluoridation-linked increase in cancer death rate could be observed in populations 0-24 and 25-44 years of age. In populations 45-64 years of age, a fluoridation-linked increase in cancer death rate of 15/100,000 population was observed (P < .02); in populations 65+ years of age, an increase of 35/100,000 was observed (P < .05). The fluoridation-linked increase in cancer death rate could not be ascribed to changes in the racial or sex compositions of the fluoridated and nonfluoridated populations.
The present investigation was carried out to provide biochemical and ultrastructural evidences on the aberrations that appear in teeth in human Dental Fluorosis (DF), a condition caused by excess intake of fluoride. Human fluorosed teeth were obtained from the OPD of Madras Dental College, Chennai. Normal tooth samples were also collected from patients who opted for denture. The samples were investigated for fluoride and calcium contents, besides the tooth surfaces were examined under scanning electron microscope to assess the morphological aberrations. An increase in fluoride content and decrease in calcium content in fluorosed human teeth were observed when compared to the control. The scanning electron micrographs of the enamel surface of fluorosed human teeth show pitted, uneven and rough surfaces. Cracks and fissures were also observed on the enamel surface of fluorosed teeth. The present study provides evidence to suggest that pitting, perforation and structural alterations in DF are the result of impaired enamel mineralization.