A V-shaped bis-coumarin based fluorescence probe for F- detection in tea infusions and potable water and bioimaging applications in living systems.

Fluorine (F) is a pivotal element in the formation of human dental and skeletal tissues, and the consumption of water and tea constitutes a significant source of fluoride intake. However, prolonged ingestion of water and tea with excessive fluoride content can lead to fluorosis, which poses a serious health hazard. In this manuscript, a novel turn-on fluorescent probe DCF synthesized by bis-coumarin and tert-butyldiphenylsilane (TBDPS) was introduced for detecting F- in potable water and tea infusions. By leveraging the unique chemical affinity between fluoride and silicon, F- triggers the silicon-oxygen bond cleavage in DCF, culminating in a conspicuous emission of yellow fluorescence. Validated through a succession of optical tests, this probe exhibits remarkable advantages in terms of superior selectivity, a low detection limit, a large Stokes shift, and robust interference resistance when detecting inorganic fluoride. Moreover, it can serve as portable test strips for on-site real-time identification and quantitative analysis of F-. Furthermore, the application of DCF for in-situ monitoring and imaging of F- in zebrafish and soybean root tissues proved its significant value for F- detection in both animal and plant systems. This probe potentially functions as an efficient instrument for delving into the toxic mechanisms of fluoride in physiological processes.

Water Fluoridation and Birth Outcomes in California.

BACKGROUND: There is a lack of research on the relationship between water fluoridation and pregnancy outcomes. OBJECTIVES: We assessed whether hypothetical interventions to reduce fluoride levels would improve birth outcomes in California. METHODS: We linked California birth records from 2000 to 2018 to annual average fluoride levels by community water system. Fluoride levels were collected from consumer confidence reports using publicly available data and public record requests. We estimated the effects of a hypothetical intervention reducing water fluoride levels to 0.7 ppm (the current level recommended by the US Department of Health and Human Services) and 0.5 ppm (below the current recommendation) on birth weight, birth-weight-for-gestational age z-scores, gestational age, preterm birth, small-for-gestational age, large-for-gestational age, and macrosomia using linear regression with natural cubic splines and G-computation. Inference was calculated using a clustered bootstrap with Wald-type confidence intervals. We evaluated race/ethnicity, health insurance type, fetal sex, and arsenic levels as potential effect modifiers. RESULTS: Fluoride levels ranged from 0 to 2.5 ppm, with a median of 0.51 ppm. There was a small negative association on birth weight with the hypothetical intervention to reduce fluoride levels to 0.7 ppm [-2.2g; 95% confidence interval (CI): -4.4, 0.0] and to 0.5 ppm (-5.8g; 95% CI: -10.0, -1.6). There were small negative associations with birth-weight-for-gestational-age z-scores for both hypothetical interventions (0.7 ppm: -0.004; 95% CI: -0.007, 0.000 and 0.5 ppm: -0.006; 95% CI: -0.013, 0.000). We also observed small negative associations for risk of large-for-gestational age for both the hypothetical interventions to 0.7 ppm [risk difference (RD)=-0.001; 95% CI: -0.002, 0.000 and 0.5 ppm (-0.001; 95% CI: -0.003, 0.000)]. We did not observe any associations with preterm birth or with being small for gestational age for either hypothetical intervention. We did not observe any associations with risk of preterm birth or small-for-gestational age for either hypothetical intervention. CONCLUSION: We estimated that a reduction in water fluoride levels would modestly decrease birth weight and birth-weight-for-gestational-age z-scores in California. https://doi.org/10.1289/EHP13732.

Groundwater vulnerability to fluoride pollution and health risk assessment in the western part of Odisha, India.

The fluoride dynamics of the Dharmagarh Block of Kalahandi District, Odisha, India, and associated health risk assessment have been studied. Complex data matrices were evaluated using groundwater quality index, fluoride pollution index, and principal component analysis to understand the geological evolution and identify potential sources for fluoride pollution. The study region comprises granite, granitic gneiss, and khondalite of hard and compact rock of Precambrian Eon, which supplies mostly the fluoride-bearing minerals. Altogether thirty-four (34) groundwater samples across the entire study area were collected and subjected to various physico-chemical analyses. The majority of the groundwater in the proposed region is hard to very hard type with Mg-HCO3 and Na-HCO3 being the two dominant facies. Groundwater contains fluoride in concentrations ranging from 0.21 to 2.26 mg/L. The statistical analysis of the quality parameters reveals the moderate positive correlation of fluoride with sodium (0.392) and pH (0.313) and week positive correlation with EC, TDS, TH, TA, Mg2+, and HCO3-, which directly depicts the initiation of fluoride problem within the study area. Based on the water quality index, 23.53% samples are good, 73.53% are poor, and 2.94% are very poor in nature. With respect to fluoride pollution index, 5.88% samples show high pollution, 55.88% samples show medium pollution, and 38.24% of samples show low pollution index. Human health risk assessment has also been carried out using the hazard quotient of fluoride. Altogether 70.59% of samples show Total Hazard Index (THI) values < 1 suggesting low risk of cancer and within the permissible range, whereas 29.41% of samples show THI > 1 suggesting the non-carcinogenic risk of pollutants, which exceeds the allowable limit for all the classes of male, female and children.

Changes in Metabolism and Content of Chlorophyll in Common Duckweed (Lemna minor L.) Caused by Environmental Contamination with Fluorides.

The impact of fluorine on plants remains poorly understood. We examined duckweed growth in extracts of soil contaminated with fluorine leached from chicken manure. Additionally, fluorine levels were analyzed in fresh manure, outdoor-stored manure, and soil samples at varying distances from the manure pile. Fresh manure contained 37-48 mg F- × kg-1, while soil extracts contained 2.1 to 4.9 mg F- × kg-1. We evaluated the physiological effects of fluorine on duckweed cultured on soil extracts or in 50% Murashige-Skoog (MS) medium supplemented with fluorine concentrations matching those in soil samples (2.1 to 4.9 mg F- × L-1), as well as at 0, 4, and 210 mg × L-1. Duckweed exposed to fluorine displayed similar toxicity symptoms whether in soil extracts or supplemented medium. Fluoride at concentrations of 2.1 to 4.9 mg F- × L-1 reduced the intact chlorophyll content, binding the porphyrin ring at position 32 without affecting Mg2+. This reaction resulted in chlorophyll a absorption peak shifted towards shorter wavelengths and formation of a new band of the F--chlorophyll a complex at λ = 421 nm. Moreover, plants exposed to low concentrations of fluorine exhibited increased activities of aminolevulinic acid dehydratase and chlorophyllase, whereas the activities of both enzymes sharply declined when the fluoride concentration exceeded 4.9 mg × L-1. Consequently, fluorine damages chlorophyll a, disrupts the activity of chlorophyll-metabolizing enzymes, and diminishes the plant growth rate, even when the effects of these disruptions are too subtle to be discerned by the naked human eye.

Comprehensive risk assessment and interactions of fluoride and boron ions in the water-sediments interface: The Red Sea, Egypt.

This study presents a baseline evaluation of the distribution, human and ecotoxicological risk, and the potential interactions of fluoride and boron in the water-sediment interface in 25 locations from incredible Red Sea tourist destinations. Results showed comparable levels of B and F in the water and sediments with previous literature. Significant positive correlation was found between B and F (r = 0.57; P<0.01). Based on the sediment/liquid partition coefficient (Kd), F is more likely to be released from the sediment into seawater (logKd< 3) than B (3< logKd< 4). pH and alkalinity may affect water-sediment interactions of B and F, respectively, while SO42- and Cl- ions had no significant effect on adsorption ability of F and B. The majority of minerals had average saturation Index (SI) > 1 referring to the over saturation of seawater with these minerals and their inability to dissolve. The formation of CF, FAP, and CFAP may be related to the high correlation between Fw (r = 0.928, P< 0.01; r = 0.527, P< 0.01; r = 0.608, P< 0.01) and Bw (r = 0.38, P< 0.05; r = 0.38, P< 0.05; r = 0.397, P< 0.05). Total hazard quotient (THQ) for children and adults were <1, revealing no health risks from exposure to B and F through ingestion and skin contact while swimming. The risk characterization ratio; RCRmix(MEC/PNEC) showed high short-term risks to aquatic organisms. Further investigations might emphasis on emerging mitigation strategies to address these concerns.

Arsenic and fluoride in groundwater triggering a high risk: Probabilistic results using Monte Carlo simulation and species sensitivity distribution.

The widespread presence of arsenic (As) and fluoride (F-) in groundwater poses substantial risks to human health on a global scale. These elements have been identified as the most prevalent geogenic contaminants in groundwater in northern Mexico. Consequently, this study aimed to evaluate the human health and ecological risks associated with the content of As and F- in the Meoqui-Delicias aquifer, which is in one of Mexico's most emblematic irrigation districts. Concentrations of As and F- were measured in 38 groundwater samples using ICP-MS and ion chromatography, respectively. Overall, these elements showed a similar trend across the aquifer, revealing a positive correlation between them and pH. The concentration of As and F- in the groundwater ranged from 5.3 µg/L to 303 µg/L and from 0.5 mg/L to 8.8 mg/L, respectively. Additionally, the levels of As and F- surpassed the established national standards for safe drinking water in 92% and 97% of samples, respectively. Given that groundwater is used for both agricultural purposes and human activities, this study also assessed the associated human health and ecological risks posed by these elements using Monte Carlo simulation and Species Sensitivity Distribution. The findings disclosed a significant noncarcinogenic health risk associated with exposure to As and F-, as well as an unacceptable carcinogenic health risk to As through water consumption for both adults and children. Furthermore, a high ecological risk to aquatic species was identified for F- and high to medium risks for As in the sampling sites. Therefore, the findings in this study provide valuable information for Mexican authorities and international organizations (e.g., WHO) about the adverse effects that any exposure without treatment to groundwater from this region represents for human health.

Direct fluoride monitoring using a fluorogenic RNA-based biosensor.

Fluorinated compounds, whether naturally occurring or from anthropogenic origin, have been extensively exploited in the last century. Degradation of these compounds by physical or biochemical processes is expected to result in the release of fluoride. Several fluoride detection mechanisms have been previously described. However, most of these methods are not compatible with high- and ultrahigh-throughput screening technologies, lack the ability to real-time monitor the increase of fluoride concentration in solution, or rely on costly reagents (such as cell-free expression systems). Our group recently developed "FluorMango" as the first completely RNA-based and direct fluoride-specific fluorogenic biosensor. To do so, we merged and engineered the Mango-III light-up RNA aptamer and the fluoride-specific aptamer derived from a riboswitch, crcB. In this chapter, we explain how this RNA-based biosensor can be produced in large scale before providing examples of how it can be used to quantitatively detect (end-point measurement) or monitor in real-time fluoride release in complex biological systems by translating it into measurable fluorescent signal.

Microwell fluoride assay screening for enzymatic defluorination.

There is intense interest in removing fluorinated compounds from the environment, environments are most efficiently remediated by microbial enzymes, and defluorinating enzymes are readily monitored by fluoride determination. Fluorine is the most electronegative element. Consequently, all mechanisms of enzymatic C-F bond cleavage produce fluoride anion, F-. Therefore, methods for the determination of fluoride are critical for C-F enzymology and apply to any fluorinated organic compounds, including PFAS, or per- and polyfluorinated alkyl substances. The biodegradation of most PFAS chemicals is rare or unknown. Accordingly, identifying new enzymes, or re-engineering the known defluorinases, will require rapid and sensitive methods for measuring fluoride in aqueous media. Most studies currently use ion chromatography or fluoride specific electrodes which are relatively sensitive but low throughput. The methods here describe refashioning a drinking water test to efficiently determine fluoride in enzyme and cell culture reaction mixtures. The method is based on lanthanum alizarin complexone binding of fluoride. Reworking the method to a microtiter well plate format allows detection of as little as 4 nmol of fluoride in 200 µL of assay buffer. The method is amenable to color imaging, spectrophotometric plate reading and automated liquid handling to expedite assays with thousands of enzymes and/or substrates for discovering and improving enzymatic defluorination.

Innovative soil fluoride estimation method: dual polarimetric saline-associated fluoride for agricultural patches.

Fluoride and its constituents in soil affect plant growth and public health. In this study, soil fluoride was measured for the semi-arid regions in southern India, using Sentinel-1 data in conjunction with the dual polarimetric saline-associated fluoride model (also known as fluoride model). A loss angle was estimated from laboratory-based dielectric components of soil samples with strong electrical conductivity under high and low fluoride conditions. The conductivity loss angle and real and imaginary dielectric constants were used to study fluoride salt's dielectric behavior. The imaginary dielectric component sensitive to dielectric loss could predict fluoride across large areas over time. This was statistically analyzed with R2 = 0.86, RMSE = 1.90, and bias = 0.35 showing a promising depiction that C-band SAR data can distinguish fluoride levels over varied clay soil and soil with varying vegetation development. Moreover, the association between biomass and simulated fluoride helped to identify fluoride-tolerant and non-tolerant crops. The study found that Sorghum and Oryza sativa tolerate saline-associated fluoride, whereas Peanut and Allium do not. Furthermore, the model successfully retrieves fluoride from saline salts based on tangent loss.

Spatial distribution, geochemical processes of high-content fluoride and nitrate groundwater, and an associated probabilistic human health risk appraisal in the Republic of Djibouti.

In the northern East African Rift System, the Republic of Djibouti relies exclusively on groundwater, with levels of fluoride (up to 14 mg/L) and nitrate (up to 256 mg/L) posing potential health risks. To address this, 362 samples were considered, including 133 shallow groundwater samples, along with new and previously published data dating back to 2012 on deep (88) and thermal (141) groundwater samples. To understand the enrichment mechanisms, dissolved anion and cation constituents, geochemical and thermodynamic tools, and stable isotope ratios, such as δ2H(H2O), δ18O(H2O), δ15N(NO3-), and δ18O(NO3-), were used. In particular, two activity diagrams (Mg2+ vs. Ca2+ and Na+ vs. Ca2+), focused on aqueous and solid fluoride species in an updated thermodynamic dataset of 15 fluoride-bearing minerals, are shown for the first time. The dataset offers new and valuable insights into fluoride geochemistry (classic thermodynamic datasets combined with geochemical codes rely solely on fluorapatite and fluorite F-bearing minerals). Activity diagrams and geochemical modeling indicate that mineral dissolution primarily drives groundwater fluoride enrichment in all water types, whereas the elevated nitrate levels may stem from organic fertilizers like animal manure, as indicated by nitrate isotopes and NO3-/Cl- vs Cl- diagrams. Despite the arid climate and 2H18O enrichment in shallow waters, evaporation seems to play a minor role. Monte Carlo simulations and sensitivity analysis were used to assess the health risks associated with elevated F- and NO3- concentrations. Mapping-related spatial distribution analysis identified regional contamination hotspots using a global Moran's I and GIS tools. One fluoride and three nitrate contamination hotspots were identified at a p-value of 0.05. Groundwater chemistry revealed that 88 % of groundwater being consumed exceeded the permissible levels for fluoride and nitrate, posing potential health risks, particularly for teenagers and children. This study pinpoints specific areas with excessive nitrate and fluoride contamination, highlighting a high non-carcinogenic risk.

Analysis of indicators of caries of permanent teeth in children according to the endemic features of the Poltava region, Ukraine.

OBJECTIVE: Aim: This research is focused at analyzing the indicators and substantiating the peculiarities of caries prevention in permanent teeth in schoolchildren of Poltava region, taking into account the endemic features of the Poltava region. PATIENTS AND METHODS: Materials and Methods: A comparative study was conducted among 608 pupils of secondary schools in Kremenchuk, who consumed drinking water with fluoride concentrations in the lower limits of the norm, and 1214 pupils of secondary schools in Poltava, who consumed drinking water with fluoride concentrations in the optimal upper limits of the norm. RESULTS: Results: The rates of caries in permanent teeth in children living in a region with fluoride concentrations in drinking water in the optimal-upper normal range are several times lower than in children of the same age living in a region with fluoride concentrations in drinking water in the lower normal range, and a significant increase in the prevalence and intensity of caries is observed from 7 to 9 to 12 years of age, as teeth after eruption are most vulnerable to caries. In a region where the fluoride concentration in drinking water is in the optimal-upper range of the norm, children with early forms of fluorosis have the lowest prevalence and intensity of caries. CONCLUSION: Conclusions: Endemic features of the region directly affect the prevalence and intensity of the caries process. In regions with a fluoride concentration in drinking water within the optimal upper limits of the norm, prevention of caries in permanent teeth in children should be carried out taking into account the presence of fluorosis.

Naphthalimide-based new architecture for fluorescence turn-on sensing of Cu2+ and colorimetric detection of F-/CN.

A new molecular structure 1 has been developed on naphthalimide motif. The amine and triazole binding groups have been employed at the 4-position of naphthalimide to explore the sensing behavior of molecule 1. Single crystal x-ray diffraction and other spectroscopic techniques confirm the identity of 1. Compound 1 exhibits high selectivity and sensitivity for Cu2+ ions in CH3CN. The binding of Cu2+ shows âˆ¼ 70-fold enhancement in emission at 520 nm. The binding follows 1:1 interaction and the detection limit is determined to be 6.49 × 10-7 M. The amine-triazole binding site in 1 also corroborates the detection of F- through a colour change in CH3CN. Initially H-bonding and then deprotonation of amine -NH- in the presence of F- are the sequential steps involved in F- recognition with a detection limit of 4.13 × 10-7 M. Compound 1 is also sensible to CN- like F- ion and they are distinguished by Fe3+ ion. Cu2+-ensemble of 1 fluorimetrically recognizes F- among the tested anions and vice-versa. The collaborative effect of amine and triazole motifs in the binding of both Cu2+ and F-/CN- has been explained by DFT calculation.

Identification of groundwater pollution sources and health risk assessment in the Fengshui mining area of Central Shandong, China.

The crux of groundwater protection lies in a profound understanding of the sources of pollutants and their impacts on human health. This study selected 47 groundwater samples from the Fengshui mining area in central Shandong Province, China, employing advanced hydrogeochemical techniques, positive matrix factorization (PMF), and Monte Carlo analysis methods, aimed at unveiling the characteristics, origins, and health risks of water pollutants. The results indicated that the majority of samples exhibited a slightly alkaline nature. Notably, the concentrations of fluoride (F-) and nitrate (NO3-) exceeded China's safety standards in 40.43% and 23.40% of the samples, respectively. Moreover, a water quality index (WQI) below 50 was observed in approximately 68.09% of the sites, suggesting that the water quality in these areas generally met acceptable levels. However, regions with higher WQI values were predominantly located in the northern and southern parts of the mining area. PMF analysis revealed that regional geological and industrial activities were the primary factors affecting water quality, followed by mining discharges, fundamental geological and agricultural processes, and leachate enrichment activities. The health risk assessment highlighted the heightened sensitivity of the youth demographic to fluoride, with a more pronounced non-carcinogenic risk compared to nitrate, affecting about 31.89% of the youth population. Hence, it is imperative for local authorities and relevant departments to take prompt actions to remediate groundwater contamination to minimize public health risks.

Water quality and geochemical facie of high-altitude lakes in Tawang, Eastern Himalaya, India.

High-altitude lakes (HALs) can be used as a supplement or alternative source of water in areas where there is a water shortage. When these lakes are efficiently managed, they can supply more water resources to fulfil the increasing demand. Water quality assessment aids in the identification of adequate and safe drinking water sources. It minimizes threats to the public's health by making sure that lake water extraction fulfills safety and health regulations. Water quality and hydrogeochemical study was conducted on six HALs of the Tawang district of Arunachal Pradesh during the year 2022. The water quality index (WQI) values varied from excellent to poor (33.87 to 101.95). Lake 6 stands out with its exceptional water quality as it had the minimum average WQI value of 52.98. In contrast, Lake 5 had the lowest water quality among the studied lakes with the maximum average WQI value of 95.31. However, the water might not be safe to drink due to the elevated levels of fluoride in these lakes. It is crucial to address and minimize the high fluoride levels to ensure the safety and acceptability of the water for consumption. The Piper diagram showed that Ca2+ > Mg2+ > Na+ > K+ and HCO3- > Cl- > SO42-, respectively, were the primary cations and anions present in these lakes. The Gibbs diagram also demonstrated the effect of rock weathering and precipitation dominance on the water chemistry in the research area. These results provide insightful information about the water quality of HALs, which is essential information for concerned government departments and agencies to manage water issues more efficiently. Based on current research, the HALs in this region have a lot of potential to meet the growing demand for drinking water.

Adaptive responses of the ileum of NOD mice to low-dose fluoride: A proteomic exploratory study.

Fluoride (F) has been employed worldwide to control dental caries. More recently, it has been suggested that the consumption of low doses of F in the drinking water may reduce blood glucose levels, introducing a new perspective for the use of F for the management of blood glucose. However, the exact mechanism by which F affects blood glucose levels remains largely unexplored. Given that the small gut plays a pivotal role in glucose homeostasis, the aim of this study was to investigate the proteomic changes induced by low doses of F in the ileum of female nonobese-diabetic (NOD) mice. Forty-two female NOD mice were divided into two groups based on the F concentration in their drinking water for 14 weeks: 0 (control) or 10 mgF/L. At the end of the experimental period, the ileum was collected for proteomic and Western blot analyses. Proteomic analysis indicated an increase in isoforms of actin, gastrotropin, several H2B histones, and enzymes involved in antioxidant processes, as well as a decrease in enzymes essential for energy metabolism. In summary, our data indicates an adaptive response of organism to preserve protein synthesis in the ileum, despite significant alterations in energy metabolism typically induced by F, therefore highlighting the safety of controlled fluoridation in water supplies.

A Bayesian benchmark concentration analysis for urinary fluoride and intelligence in adults in Guizhou, China.

Environmental fluoride exposure has been linked to numerous cases of fluorosis worldwide. Previous studies have indicated that long-term exposure to fluoride can result in intellectual damage among children. However, a comprehensive health risk assessment of fluorosis-induced intellectual damage is still pending. In this research, we utilized the Bayesian Benchmark Dose Analysis System (BBMD) to investigate the dose-response relationship between urinary fluoride (U-F) concentration and Raven scores in adults from Nayong, Guizhou, China. Our research findings indecate a dose-response relationship between the concentration of U-F and intelligence scores in adults. As the benchmark response (BMR) increased, both the benchmark concentration (BMCs) and the lower bound of the credible interval (BMCLs) increased. Specifically, BMCs for the association between U-F and IQ score were determined to be 0.18 mg/L (BMCL1 = 0.08 mg/L), 0.91 mg/L (BMCL5 = 0.40 mg/L), 1.83 mg/L (BMCL10 = 0.83 mg/L) when using BMRs of 1 %, 5 %, and 10 %. These results indicate that U-F can serve as an effective biomarker for monitoring the loss of IQ in population. We propose three interim targets for public policy in preventing interllectual harm from fluoride exposure.

Industrial fluoride emissions and their spatial characteristics in the Nansi Lake Basin, Eastern China.

Excessive fluoride emissions threaten ecological stability and human health. Previous studies have noted that industrial sources could be significant. However, quantifying industrial fluoride emissions has not been yet reported. In this study, both bottom-up and top-down approaches were used to estimate the fluoride emissions in the Nansi Lake Basin. Global and local spatial autocorrelation were adopted to reveal the spatial agglomeration effects. The fluoride emissions calculated by the bottom-up approach were larger than those calculated by the top-down method. The highest fluoride input mainly occurred in Zoucheng and Mudan. The highest fluoride emissions mainly occurred in Zoucheng and Rencheng using the bottom-up approach. The highest fluoride emissions mainly occurred in Zoucheng and Yanzhou using the top-down approach. Mining and washing of bituminous coal and anthracite (BAW) was the most significant source of fluoride input and emissions. A significant spatial agglomeration effect of fluoride emissions was found. These findings could provide a method for accurate industrial fluoride emission estimation, complement the critical data on the fluoride emissions of main industrial sectors, and provide a scientific basis for tracing fluoride sources.

The effect of combined use of resin infiltration with different bioactive calcium phosphate-based approaches on enamel white spot lesions: An in vitro study.

OBJECTIVES: This in vitro study aimed to evaluate the effect of resin infiltration combined with casein phosphopeptide-amorphous calcium phosphate with fluoride (CPP-ACPF) or bioactive glass (BAG) on the stability of enamel white spot lesions (WSLs) treatment. MATERIALS AND METHODS: Eighty-four enamel blocks were prepared from the buccal surfaces of sound human premolars. All enamel blocks were placed in a demineralisation solution for 3 days to establish the artificial enamel WSLs. Enamel blocks with WSLs were randomly divided into three groups (n = 28 each group): RI/B: one-off resin infiltration followed by twice daily BAG treatment; RI/C: one-off resin infiltration followed by twice daily CPP-ACPF treatment; RI: one-off resin infiltration treatment only (as control) and subjected to pH cycling for 7 days. Surface morphology, elemental analysis, crystal characteristics, surface roughness and microhardness of enamel surfaces were investigated by scanning electron microscopy and energy-dispersive spectrometry observation, X-ray diffraction (XRD), atomic force microscope and Vickers' hardness testing, respectively. RESULTS: Mean values of the surface roughness (mean±standard deviation (nm)) were 24.52±5.07, 27.39±5.87 and 34.36±4.55 for groups RI/B, RI/C and RI respectively (p = 0.003). The calcium to phosphate ratios were 1.32±0.16, 1.22±0.26 and 0.69±0.24 for groups RI/B, RI/C and RI respectively (p < 0.001). XRD revealed apatite formation in all three groups. The mean enamel surface microhardness (kg/mm2) of the groups were 353.93±28.49, 339.00±27.32 and 330.38±22.55 for groups RI/B, RI/C and RI respectively (p = 0.216). CONCLUSIONS: Resin infiltration combined with CPP-ACPF or BAG remineralisation appears to improve the surface properties of WSLs. CLINICAL SIGNIFICANCE: The combination of resin infiltration and CPP-ACPF/BAG remineralisation may be a potential treatment for the management of the WSLs.

Hydrogeochemical characteristics, stable isotopes, positive matrix factorization, source apportionment, and health risk of high fluoride groundwater in semiarid region.

Chronic exposure to high fluoride (F-) levels in groundwater causes community fluorosis and non-carcinogenic health concerns in local people. This study described occurrence, dental fluorosis, and origin of high F-groundwater using δ2H and δ18O isotopes at semiarid Gilgit, Pakistan. Therefore, groundwater (n = 85) was collected and analyzed for F- concentrations using ion-chromatography. The lowest F- concentration was 0.4 mg/L and the highest 6.8 mg/L. F- enrichment is linked with higher pH, NaHCO3, NaCl, δ18O, Na+, HCO3-, and depleted Ca+2 aquifers. The depleted δ2H and δ18O values indicated precipitation and higher values represented the evaporation effect. Thermodynamic considerations of fluorite minerals showed undersaturation, revealing that other F-bearing minerals viz. biotite and muscovite were essential in F- enrichment in groundwater. Positive matrix factorization (PMF) and principal component analysis multilinear regression (PCAMLR) models were used to determine four-factor solutions for groundwater contamination. The PMF model results were accurate and reliable compared with those of the PCAMLR model, which compiled the overlapping results. Therefore, 28.3% exceeded the WHO permissible limit of 1.5 mg/L F-. Photomicrographs of granite rocks showed enriched F-bearing minerals that trigger F- in groundwater. The community fluorosis index values were recorded at > 0.6, revealing community fluorosis and unsuitability of groundwater for drinking.

Assessing water quality index and health risk using deterministic and probabilistic approaches in Darab County, Iran; A machine learning for fluoride prediction.

The present study employed deterministic and probabilistic approaches to determine the Water Quality Index (WQI) and assess health risks associated with water consumption in Darab County, Iran. Additionally, pollution levels were predicted using a machine-learning algorithm. The study's findings indicate that certain physicochemical parameters of water in some locations exceeded permissible limits (WHO or EPA), with 79.00 % of total hardness (TH) and 21.74 % of Total dissolved solids (TDS) levels exceeding standard values. The WQI for drinking water was determined to be 94.56 % using the deterministic approach, and 98.4 % of samples included the excellent and good categories according to the WQI classification system using the probabilistic approach. Fluoride (F) exhibited the most substantial impact on WQI values. The Artificial Neural Network (ANN) analysis findings suggest that the pH, nitrate (NO3), and TDS are the most significant factors affecting the prediction of F concentration in water. Multivariate analysis demonstrated that anthropogenic, especially agriculture and geogenic factors, contributed to the water quality in this area. The health risk assessment (HRA) using deterministic methods revealed that water consumption posed a relatively high risk in certain areas. However, Monte Carlo simulation demonstrated that the 5th and 95th percentiles of Hazard Index (HI) for children, teenagers, and adults were within limits of (0.14-2.38), (0.09-1.29), and (0.10-1.00) respectively, with a certainty level of 70 %, 91 %, and 95 %. Interactive indices revealed that the intake of IR and NO3-IR in children, BW and F-BW in teenagers, and NO3 and NO3-IR in adults significantly impacted health risks. Based on these findings, augmenting water treatment processes, regulating fluoride concentrations, and advocating for sustainable agricultural practices complemented by continuous monitoring is imperative.