Health Risk Assessment Of Fluoride Research Articles

Shallow groundwater quality and health risk assessment of fluoride and arsenic in Northwestern Jiangsu Province, China

Assessing groundwater quality is critical to regional water resource conservation and human health safety, especially in areas with co-existence of toxic constituents fluoride (F−) and arsenic (As). In this study, fourteen groundwater samples were collected in Feng County, Northwestern Jiangsu Province to identify dominant contaminants and their spatial distribution and health risk. The composition and variation characteristics of major ions (K+, Na+, Ca2+, Mg2+, Cl−, SO42−, HCO3−, and NO3−) and trace elements (F−, As, and Mn) were analyzed. The hydrochemical results revealed that high F− groundwater was mainly distributed in the northern areas whereas As-riched groundwater was primarily distributed in southern areas. Notably, over 85.7% and 21.4% of the shallow groundwater samples exceeded the drinking water quality standard of 1.5 mg/L for F− and 10 µg/L for As, respectively. Based on the water quality index (WQI) appraisal result, 71.4% of the groundwater in the study area is classified as “poor”, and thus unsuitable for drinking directly. We assessed the human non-carcinogenic health risk of F− (HQFluoride) and As (HQArsenic) and the carcinogenic health risk of As (CRArsenic). The calculated hazard quotient (HQ) for F− indicated nearly all groundwater samples have an unacceptable risk (HQ > 1) for each age group. However, HQArsenic values revealed that 28.6%, 21.4%, 21.4%, and 21.4% of groundwater samples posed potential non-carcinogenic health risks for infants, children, females, and males, respectively. The calculated results of CRArsenic showed that 0%, 21.4%, 28.6%, and 28.6% of groundwater samples posed unacceptable health risks (CR > 1.0 × 10−4) to infants, children, females, and males, respectively. The groundwater irrigation suitability assessment results showed that 21.4% of samples were doubtful to unsuitable for irrigation, and 85.7% owed magnesium hazards. The findings of this study will assist policymakers in formulating proper remedial policies and mitigation strategies to ensure the safety of drinking and irrigation water.

Hydrogeochemical characterization and non-carcinogenic health risk assessment of fluoride and nitrate-affected groundwater in northern parts of Tumkur district, Karnataka, India

Groundwater contamination from geogenic and anthropogenic sources is a significant concern for the public health across the globe. In India, fluoride and nitrate contamination are the most prevalent contaminants in the groundwater. This study evaluated groundwater quality in four over-exploited sub-districts of Tumkur district in Karnataka by collecting 143 samples from post and pre-monsoon seasons and using different hydrogeochemical, statistical and bivariate graphical approaches. Comparison with Drinking Water Standard guidelines revealed elevated levels of fluoride, nitrate, and total dissolved solids (TDS), rendering the groundwater unsuitable for drinking. According to Chadha’s diagram, the predominant groundwater type is Na-Cl, and Gibbs diagram suggested the influence of rock dissolution and weathering. Bivariate plots indicated that hydrogeochemical characteristics were primarily influenced by silicate weathering of minerals, cation ion exchange processes, and anthropogenic factors. A non-carcinogenic health risk assessment was conducted using two different hazard index (HI) approaches from United States Environmental Protection Agency (USEPA) and Agency for Toxic Substances and Disease Registry (ATSDR). It was found that health risk associated with fluoride is more significant than the health risk from nitrate, with children being the most affected, followed by adolescents and adults. A holistic approach to assess cumulative health risks from fluoride and nitrate contamination in groundwater, as demonstrated in this study, promotes the synergistic advancement of SDG 3: Good health and well-being and SDG 6: Clean water and sanitation.

Non-carcinogenic Health Risk Assessment of Fluoride and Nitrate of Groundwater–A Case Study of the Central Dry Zone of Chikkanayakanahalli Taluk, Tumkur District, Karnataka

Non-carcinogenic Health Risk Assessment of Fluoride and Nitrate of Groundwater–A Case Study of the Central Dry Zone of Chikkanayakanahalli Taluk, Tumkur District, Karnataka

Spatial-temporal variability and probabilistic health risk assessment of fluoride from lentic ecosystem, Türkiye

ABSTRACT Thrace Region is a part of the Marmara Region of Türkiye. There are many natural and artificial stagnant water habitats in the region that are used for irrigation and drinking water supply. This study is intended to determine the spatial-temporal variability and probabilistic health risk of fluoride exposure in the water of stagnant water bodies in the Thrace region. A total of 33 stagnant water bodies were selected, and water samples were collected during the dry and wet seasons of 2021–2022. The fluoride levels were measured using a spectrophotometric method (wavelength is 588 nm). The fluoride accumulations varied from 0.16–0.64 mg/L for the natural lakes, 0.04–0.74 mg/L for the reservoirs, and 0.01–0.53 mg/L for the artificial ponds. The World Health Organization (WHO) suggested a level of fluoride in drinking water of 0.5 to 1.5 mg/L. The study area had a fluoride deficiency of less than 0.5 mg/L in natural water bodies during the wet season (87.87%) and the dry season (93.93%), which might be a potential threat to dental health. Estimation Daily Intake (EDI) and Hazard Quotient (HQ) widely used health risk assessment methods were applied to the data in the current research to describe the non-carcinogenic risk of fluoride. All the calculated hazard quotient (HQ) values, both in the dry and wet seasons and in all age groups, were recorded as below 1. Both teenagers and children living in the central part of the study area are at higher risk than infants and adults. To evaluate model uncertainty, Monte Carlo simulations were employed. The outcome of the sensitivity analysis revealed that the major risks to the health of the inhabitants are the high content of fluoride and their daily intake of water.

Enrichment Mechanism and Health Risk Assessment of Fluoride in Groundwater in the Oasis Zone of the Tarim Basin in Xinjiang, China

Enrichment Mechanism and Health Risk Assessment of Fluoride in Groundwater in the Oasis Zone of the Tarim Basin in Xinjiang, China

Fuzzy logic-based health risk assessment of fluoride in groundwater used as drinking source in Sira region, Tumkur, India.

Fluoride contamination in drinking water is a serious public health concern across the world, and more than 90 million people in India are affected by health risks associated with fluoride. Though the fatality due to fluoride chronic toxicity is uncommon, the exposure to fluoride at different concentration levels shows various adverse health effects such as dental and skeletal fluorosis, multiorgan failure, cognitive and behavioural effects. Hence, the objectives of the present study are to understand the hydrogeochemistry and drinking water suitability of groundwater of the Sira region, Karnataka, India, and to understand the occurrence of fluoride and its health risks using the United State Environmental Protection Agency (US EPA) method and fuzzy logic concepts. Forty-six samples were collected from each pre and post-monsoon season. The hydrogeochemistry studied through Chadha's diagram and Gibb's diagram indicated that the groundwater in this region is of Na-Cl type and the hydrogeochemistry is majorly controlled by rock-water interaction and followed by evaporative dominance. Water quality parameters were compared with drinking water standards guidelines, and the results showed that around 50% of the samples were contaminated with fluoride. The occurrence of high levels of fluoride in the study region is associated to the presence of granitic rocks and it is influenced by high pH and low calcium dissolution in the groundwater. Based on US EPA method, the order ofpopulation group under the risk of dental and skeletal fluorosis, is children > adolescents > adults. A fuzzy inference system model is developed to assess the health risk due to fluoride and its output gives severity levels of each type of health risk, i.e. dental caries, dental fluorosis and skeletal fluorosis. The results of the application of the fuzzy inference system model in the Sira region showed that the children (< 8Yr.) are more susceptible to the moderate risk of dental caries, dental fluorosis and skeletal fluorosis. Whereas adolescents (8-18Yr.) and adults (> 18Yr.) are less susceptible to low-very low risk. Hence, health risks associated with fluoride can be better addressed with the help of a fuzzy inference system model which can be used for more reliable and grounded results to improve the quality of decision-making.

Monitoring and Health Risk Assessment of Fluoride in Drinking Water Based on Monte Carlo Simulation and Sensitivity Analysis: a Study in Rural Areas of East Azerbaijan Province, Iran

Monitoring and Health Risk Assessment of Fluoride in Drinking Water Based on Monte Carlo Simulation and Sensitivity Analysis: a Study in Rural Areas of East Azerbaijan Province, Iran

Spatial-Temporal Variation and Health Risk Assessment of Fluoride in Surface Water in the Tibetan Plateau.

The Tibetan Plateau (TP) is known as the “Asian Water Tower” and provides vital drinking water for residents of China and Southeast Asian countries. However, large-scale regional research on water quality in this climate-sensitive and ecologically-fragile area is still lacking. Considering that drinking from fluoride-contaminated water poses serious health concerns worldwide, especially in Asian counties, it is urgent to clarify the spatial–temporal distribution characteristics, influencing factors, and health risk of fluoride in surface water in the TP. In this study, a total of 2697 surface water samples from major rivers and typical lakes in the TP were systematically analysed. Overall, fluoride concentrations ranged from 0.003 to 6.240 mg L−1 and varied among water periods, water basins and even water types. Pearson’s correlation analysis showed that the distribution of fluoride concentration was closely related to the regional climate and positively correlated with anthropogenic activities. Probabilistic health risk assessment revealed that potential hazards in the Inner Basin were the highest for all age groups (HR > 1), especially for infants and adults (HR > 3), while the risks in most other water basins were acceptable (HR < 1). Our findings can provide scientific support for fluorosis prevention, and guide water resource utilization in the TP and adjacent regions.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12403-022-00490-4.

Distribution, prevalence and health risk assessment of fluoride and arsenic in groundwater from lower Gangetic plain in West Bengal, India

Distribution pattern of fluoride and arsenic in groundwater (n = 984) from 35 wards of Rajpur-Sonarpur Municipality and its associated health risk have been evaluated. Presence of fluoride ≥1.5 mg/L (mean = 1.9 mg/L, range: 1.51–2.9 mg/L) and <1.5 mg/L (mean = 0.6 mg/L, range: 0.01–1.49 mg/L), whereas, for arsenic ≥10 μg/L (mean = 56.2 μg/L, range: 10.1–213 μg/L) and <10 μg/L (mean = 3.3 μg/L, range: <3–9.7 μg/L) have been observed in the studied groundwater samples. Simultaneous occurrence of fluoride and arsenic above their permissible limit in drinking water were found from two wards (ward number 6 and 7). About 13% and 16% of the collected groundwater samples (n = 984) have been found beyond the permissible limit of fluoride and arsenic, respectively. Mean concentrations of calcium and iron in groundwater were 31 mg/L (range: 7.3–184 mg/L) and 3.79 mg/L (range: <0.05–50.4 mg/L), respectively. The distribution of both fluoride and arsenic was established with a moderate positive correlation value (r = 0.30) and their relationship is dependent on the interrelationship between Ca and Fe. While the negative correlation between F− and Ca (r = −0.33) designates the increasing F−/Ca ratio in solution. Cluster analysis showed that calcium, iron and the two above contaminants are likely to be highly concentrated in the depth ranges 30.5–60.9 m, 60.9–152 m and 152–305 m. The highest concentration of both the toxicants has been observed in the depth range of 24.4–30.5 m. Weak (fluoride) to strong (arsenic) correlation between water & urine showed exposure of two toxic contaminants. Modelled Average Daily Dose (ADD) and Targeted Hazard Quotient (THQ) of fluoride and arsenic were found maximum for adults followed by teenagers and children. Cancer risk of arsenic was estimated higher than the threshold value among all the age groups.

Concentration, spatial distribution, and health risk assessment of fluoride in rural drinking water resources, North Khorasan Province, Iran

ABSTRACT Presence of fluoride in drinking water resources is one of the most important challenges related to water management and health issues. This study aimed to monitor the fluoride concentration in rural areas of North Khorasan province, Iran. During a seven-year sampling period, the water quality of over 500 points was assessed annually, based on SPADNS colorimetric method. The geostatistical analyses and spatial distribution of fluoride were performed through global Moran’s I index (spatial autocorrelation), and inverse distance weighting (IDW). In addition, the health impact probabilities of fluoride were evaluated via comparing concentrations with Iran national standard and the health risk assessment method recommended by EPA. According to the results, the measured concentrations of fluoride were in the range of 0–8.73 mg/L (average ± SD = 0.855 ± 0.458 mg/L). The lowest fluoride concentrations were determined in Esfarayen and Farouj counties (0.63 mg/L) and highest ones in Maneh Samalghan (0.9 mg/L). Moreover, Global Moran’s I was calculated to be close to zero, indicating a random distribution of fluoride throughout the province. The average THQs for adult and children age groups were 4.94 and 3.61, respectively, which showed a high non-carcinogenic risk for both adult and children age groups. However, the concentration of fluoride in all studied water resources has not exceeded the standard and was in a good condition. Therefore, it is necessary to control the excessive concentrations, especially in areas with higher amounts.

Spatial distribution and probabilistic health risk assessment of fluoride in groundwater of Angul district, Odisha, India

Presence of fluoride (F−) in drinking water both at low and high levels causes serious human health hazard. In this investigation, 106 number of groundwater samples of Angul district (Odisha, India) were collected and analyzed using statistical, hydrogeochemical, spatial distribution and health risk assessment methods. About 28% of the collected groundwater samples, the concentration of F− exceeded the permissible limit set by WHO as well as Buero of Indian Standards (BIS). Apart from this, 13 % of the collected samples the concentration of F− varied from 2 to 3.4 mgl−1 and thus, highly harmful for human consumption. The human health risk assessment was carried out as recommended by the USEPA. In the study area, the calculated hazard quotient (HQ) caused by F− contamination varied from 0.0 to 2.12 and 0.0 to 3.92 for adults and children respectively. Almost 28.30% and 58.49% groundwater samples are exhibited non-carcinogenic health risk due to F− contamination for adult and children respectively. The non-carcinogenic health risk posed by F− to children is higher than adult. Further, F− exhibited a positive correlation with bicarbonate (HCO3−) alkalinity. The concentration of F− increases with pH, which indicating that higher pH augments the dissolutions of F− ions from metamorphic and sedimentary F− containing minerals of the study area. In addition, intensive uses of phosphate fertilizer, pesticides and industrial activities may be contributing as the other sources of F− in the groundwater.

Spatial distribution, source identification, and health risk assessment of fluoride in the drinking groundwater in the Sulin coal district, northern Anhui Province, China

Abstract Previously, systematic studies of distribution, sources, and health risks of high F− groundwater used as a drinking-water source in the Sulin coal district, northern Anhui Province of China have not been carried out. In this study, 30 groundwater samples were collected in May 2019, and the data were analyzed using geographic information system, factor analysis, positive matrix factorization, and risk-based corrective action models. The results indicated that the F− concentration of the groundwater samples ranged from 0.16 to 2.06 mg/L, with a mean value of 1.10 mg/L. The F− concentrations of 53.33% of the groundwater samples exceeded China's maximum permissible limit for drinking water (1.00 mg/L). Quantificational source apportionment revealed that the weathering of F-bearing minerals is the main source (66.20%). Cation exchange (16.30%), agricultural activities (13.20%), and natural geological processes (4.30%) were the other sources of F−. The percentages of infants, children, teens, male adults, and female adults that face health risks due to excess F− intake were approximately 20.00%, 70.00%, 6.67%, 20.00%, and 10.00%, respectively. This research provided useful insights into the proper management of groundwater extraction to mitigate health problems associated with excessive F− intake.

Evaluation of groundwater quality with health risk assessment of fluoride and nitrate in Virudhunagar district, Tamil Nadu, India

The present investigation deals with the health risks due to fluoride and nitrate ions in drinking water of Virudhunagar district, Tamilnadu. A total of 143 water samples were collected for the assessment of fluoride and nitrate in groundwater. After the analysis of samples, it was found that the fluoride concentration exceeds the permissible limit of the Bureau of Indian Standards (BIS) in 61% of the analyzed samples, while nitrate concentration exceeds 37% of the samples. The water quality index of the samples employed suggests that of the analyzed samples, 19%, 33%, 36%, and 10% are excellent, good, poor, and very poor respectively, and the remaining 2% is unsuitable for drinking purposes. Piper, Chadha, and Gibbs plots were used for estimating the hydro-geochemical behavior of the samples. A correlation analysis was derived between the various parameters calculated. The non-carcinogenic health risk assessment of fluoride and nitrate was established by using the model recommended by the United States Environmental Protection Agency (USEPA). The calculated non-carcinogenic risk of fluoride and nitrate is between 0.1 to 12 with a mean of 1.8. A total of 63% of the samples exceed the acceptable limit of non-carcinogenicity recommended by the United States Environmental Protection Agency (USEPA). The spatial distribution plots were used to establish the non-carcinogenic risks and other water quality parameters.

Monitoring and health risk assessment of fluoride in drinking water of East Azerbaijan Province, Iran

ABSTRACT The amount of fluoride in drinking water sources is very important for public health. This study was conducted to evaluate the fluoride concentration in drinking water and compare the results with national and international standards, health risk assessment in non-cancerous diseases in East Azerbaijan province. This cross-sectional study was conducted in 20 large cities of East Azerbaijan province (West North of Iran) in warm (spring and summer) and cold (autumn and winter) seasons in 2017–2018.The results showed that the mean fluoride concentration in drinking water during cold and warm seasons was variable in the range of 0.19–0.65 and 0.18–0.62 mg/L, respectively. The Fluoride concentration in 80% of samples was lower than the standards. Also, the fluoride concentration in drinking water of studied cities was lower than calculated optimum concentration by Galagan and Vermillion equation. The estimated daily intake of fluoride (EDI) for infants, children, teenagers, and adults were 3.06, 2.15, 12 and 12.5 µg/kg/day, respectively. The hazard quotient (HQ) values for four age groups (infants, children, teenagers, and adults) for both seasons were lower than 1.Fluoridation and adjusting its concentrations in drinking water could be useful to compensate for its deficiency and prevent tooth decay. Based on the results, the non-carcinogenic risks of fluoride for the four exposed populations were below the safe limit.

Spatial variation and health risk assessment of fluoride in drinking water in the Chongqing urban areas, China.

Fluoride is an essential trace element for humans, and its deficiency or excess in the environment could lead to disease. To investigate the spatial distribution and health risk assessment of fluoride (F-) in drinking water, 302 tap water samples from Chongqing urban areas, China, were collected to analyze F- using an ion chromatograph. The results showed that (1) F- concentration in drinking water ranged from 0.100 to 0.503mg/L, with an average of 0.238 ± 0.045mg/L. (2) The spatial autocorrelation analysis showed that high-low clusters were mostly located in Dadukou District and Beibei District, while low-low clusters were mainly in southern Banan District. (3) The fluoride average daily doses of children, teens and adults were 0.030, 0.029 and 0.031mg/(kgday). (4) Hazard quotients of excessive fluoride (HQe) of children, teens and adults were 0.51 ± 09, 0.49 ± 0.09 and 0.52 ± 0.10, respectively (inferior to 1.00), whereas hazard quotients of inadequate fluoride (HQi) of those groups were 1.21 ± 0.26, 1.23 ± 0.26 and 1.15 ± 0.25, respectively (superior to 1.00). Therefore, average daily fluoride intake of residents with drinking water was inadequate. This could pose dental caries and osteoporosis threats for residents from Chongqing urban areas.

Geochemical and health risk assessment of fluoride and nitrate toxicity in semi-arid region of Anantapur District, South India

Abstract This paper reports to the fluoride and nitrate concentration in groundwater resources of the semi-arid region of Anantapur district, South India, and its related potential health risk assessment issues with the resident peoples. For this purpose, 50 groundwater samples were analyzed for hydrochemical parameters including major ions, fluoride and nitrate. The results revealed that most of the groundwater samples are alkaline in nature. Hydrochemical type of groundwater in the study area mainly Na+-K+-Cl−-SO42− and few samples belong to Na+-K+-HCO3−. Non carcinogenic health risks due to fluoride and nitrate exposure through consumption of groundwater were assessed using the USEPA method. In the study area groundwater samples, fluoride and nitrate concentration ranges from 1.2 to 5.9 mg/L and 36 to 92 mg/L. Based on these results, 86% of fluoride (>1.5 mg/L) and 94% of the nitrate (>45 mg/L) in groundwater samples exceed the permissible limit. The Total Hazard Index (THI) quotients for adults, children and infants had health hazards (THI > 1) in 98%, 88%, and 80% of samples, respectively. Hence, proper precautionary measures have to be taken to control health risk in this area.

Monitoring, mapping and health risk assessment of fluoride in drinking water supplies in rural areas of Maku and Poldasht, Iran.

The aim of this study was to investigate and determine fluoride concentrations in drinking water supplies in rural areas of Maku and Poldasht in West Azerbaijan Province, the northwest of Iran. Fluorosis risk assessment and characterization was also investigated. Fluoride concentrations mapping was accomplished by using the GIS system. Totally, 356 water samples, including one sample in each season, were collected from 89 water supplies providing water for 95 and 61 rural areas of Maku and Poldasht, respectively. According to the results, in Maku and Poldasht, 25 and 30 rural areas had contaminated water sources, respectively. Average annual fluoride concentrations ranged from 3.04 to 7.31mg/l in the contaminated villages of Maku, which is about 2-4.8 times higher than the maximum standard level of the Iranian drinking water standard, and 4.52-8.21mg/l in the contaminated areas of Poldasht, which is about 3-5.47 times higher than the maximum standard level. The maximum fluoride level was determined 11.12mg/l and 10.98mg/l in one of villages of Maku and Poldasht Counties in summer, respectively. Neither in Maku nor in Poldasht, water resources showed dental cavity risk, while dental fluorosis risk and skeletal fluorosis risk were very significant in some villages of both cities. Children were at most risk of fluorosis. New alternative water supplies for the contaminated villages if possible, consumption of bottled water and application of reverse osmosis are recommended as remedial actions in the contaminated areas.

Accumulation, fractionation and health risk assessment of fluoride and heavy metals in soil-crop systems in northwest China

Untreated industrial sewage and domestic wastewater irrigation has led to agricultural soil-crop system contamination by heavy metals and fluoride in Dongdagou and Xidagou stream basins, Baiyin city, China. A total of 36 pairs of soil and wheat samples (roots, stalks, leaves, husks, and grains) and 42 pairs of soil and maize samples (roots, stalk1, stalk2, stalk3, leaves, husks, corncobs and grains) were collected from Dongdagou and Xidagou stream basins to examine the accumulation, fractionation, correlation of heavy metals and F in soil-crop systems. Risks posed by heavy metals and F in this system to human health was also assessed. The total contents of F and heavy metals (Cd, Cu, Pb, Mn Zn, Cr and Ni), as well as the fraction distribution in soil, were determined. The total contents of F and heavy metals in crop tissues were also determined. The results indicated that the average contents of Cd, Cu, Pb, Mn Zn, F and Cr in Dongdagou and Xidagou stream basins exceeded the soil background value. Heavy metals and F more easily accumulated in the male inflorescence of maize. Correlation analysis showed that content of water soluble F positively were correlated with the contents of Cd, Cu, Pb, Mn Zn, Cr and Ni in exchangeable and carbonate fractions (P < 0.05). Stepwise discriminant analysis showed that the combined stresses of soil total Cu and Ni accounts for 100% effect on water soluble F accumulation in soil and crop roots. The hazard index indicated that noncancerous risk is likely to occur through maize grains and wheat grains consumption by children and adults.

Monitoring and health risk assessment of fluoride in drinking water in Babol, Mazandaran Province, Iran

Because of high variations in fluoride concentration and many contaminated areas, Iran has been known as an interesting country regarding different fluoride studies. However, researches on fluoride concentration and its effects in northern strip of Iran are limited; moreover, risk assessment studies have been neglected in these areas. Therefore, this study focused on the measurement and risk assessment of fluoride in water supplies of villages around Babol County in north of Iran. Therefore, this descriptive cross-sectional research was performed in the city of Babol, Iran, 2017. Eighty water samples were taken from 40 wells in the rural areas (40 and 40 samples in cold and warm seasons). The SPANDS method was used for the measurement of fluoride concentration. The non-carcinogenic risk of fluoride was assessed in four age groups (infant, children, teenager and adult). The risk of dental and skeletal fluorosis was counted based on the international standard. From all villages (n = 24), respectively, 4 and 3 villages in cold and warm seasons had proper fluoride concentrations according to the WHO standard; fluoride concentration of other villages was lower than the WHO minimum standard of. Any observable risk of dental and skeletal fluorosis in all studied villages for the whole age groups was not observed; the HQ of all the villages was lower than 1 except for Kalhu Dasht because its HQ was higher than 1 in infants and children in cold season. Infant and children of this village were exposed to risk of dental fluorosis. In northern areas of Iran, not only there is not a risk of dental or skeletal fluorosis, which is related to high concentration of fluoride, but also there is a risk of dental decay due to low fluoride concentration in water drinking water. However, this hypothesis needs to further study. © 2019 Desalination Publications.

Source apportionment and health risk assessment of fluoride in water resources, south of Fars province, Iran: Stable isotopes (δ18O and δD) and geochemical modeling approaches

In this study the key factors influencing fluoride enrichment in water resources, south of Fars province, Iran are investigated. For this purpose, hydrogeochemical, statistical and isotopic studies were conducted on water and dominant rock types. Impact on human health is also considered. The results indicated that fluoride concentrations in water resources range from 0.06 to 4.95 mg/L, while 67.5% of the analysed samples displayed concentrations above the world health organization guidelines for drinking water. Fluoride enrichment is associated with NaCaMgClSO4 water type and the chemical evolution of groundwater along flow path. F/Cl ratio, δ18O and δD results of water samples indicated that evaporation favored F‾ enrichment. Calculated mineral saturation indices and statistical analysis indicated that while the lithological units play a prominent role in fluoride anomalies, anthropogenic sources are negligible. Inverse geochemical modeling and calculated Chloro-Alkaline indices proved the occurrence of reverse ion exchange processes in the groundwater. Conducted leaching tests and X-ray diffraction data on abundant geological formations revealed dolomite and clay minerals as two likely candidates for contributing fluoride to the aquifers. The alkaline nature of water seems to have intensified the F‾ exchange in clay minerals with OH‾ in water. Fluoride exposure risk assessment revealed that children and adults are prone to fluoride-related diseases caused by ingestion of fluoride-rich water. Considering the prevailing climatic conditions and the ongoing geochemical processes, fluoride level in local aquifers will undoubtedly rise with time unless preventive and remediative measures are taken by the responsible authorities.