Impact of the urea nitrate content in the leaching solution on the granite weight decrease and the fluoride ion concentration

Objective To investigate and master the outcome of endemic fluorosis surveillance, the use and management situation of the facilities for decreasing fluorine in water-related endemic fluorosis in Fengshun County, Guangdong Province. Methods The surveillance was carried out according to The National Surveillance Scheme of Endemic Fluorosis in 1991 - 2007. Dazhai, Hupo and Anquan Villages in Fengshun County of Guangdong Province were selected as monitoring spots. The dental fluorosis of 8 - 12 years old children was examined with Dean index, the fluoride contents in urine and drinking water were determined with fluoride selective ion electrode method. Clinical and X-ray skeletal fluorosis of adults over 16 years of age were examined every 3 to 5 years. Results The fluoride contents in water almost reached the hygienic requirements (1.0 mg/L) in Dazhai (0.83 mg/L in 2007) and Anquan Villages(0.27 mg/L in 2007) after improving water and decreasing fluorine. The prevalence rate of dental fluorosis of students aged 8 - 12 years old fluctuated and decreased gradually, especially prevalence rate of mederate and severe fluorosis decreased obviously and reached the hygienic requirements (30%) after altering water source(20.8% in Dazhai, 3.8% in Anquan in 2007). But the fluoride contents in water were in relatively high level (1.01～2.30 mg/L), and the prevalence rate of dental fluorosis of students aged 8-12 years old(44.3% in 2007) was above the hygienic requirements in Hupo Village after improving water and decreasing fluorine. The dental fluorosis index in Daizai, Hupo and Anquan Villages dropped from 1.5, 3.0 and 1.3 in 1991 to 0.30, 0.80 and 0.10 in 2007, respectively. Epidemic strength reached respectively the criteria in mild and non-endemic areas. Fluoride contents in urine of children aged 8-12 years old in the three villages all were under the limit of 1.50 mg/L after 2002. The prevalence rate of adult clinical fluorosis [31.8% (84/264), 34.4% (131/381), 44.1% (89/202) in 1991; 11.0% (43/388), 12.9% (61/473), 9.6% (27/280) in 2005] and positive detection rate of skeletal fluorosis examined by X-ray [70.0% (35/50), 86.0% (43/50), 46.0% (23/50) in 1991 ; 20.0% (10/50), 16.0% (8/50),10.0% (5/50) in 2005] decreased gradually in Dazahai, Hupo and Anquan Villages. Conclusions The fluoride contents in the Dazhai Village and Anquan Village have met the national hygienic standard, with water fluoride content and the rate of dental fluorosis of 8 - 12 years children nearly matching to that of non-disease area. The prevalence of endemic fluorosis in the surveillance villages has been under control. Key words: Fluoride poisoning; Fluorosis; dental; Surveillance

In the present study, identification of groundwater zones that are affected by anthropogenic contaminants based on litho-hydrogeological parameters has been attempted using multi-criteria decision analysis–analytical hierarchy process (MCDA–AHP) technique in an agriculturally intensive Arang block of Raipur district, Chhattisgarh, Central India. Litho-hydrogeological factors, such as geological and aquifer characteristics, land use–land cover, depth to water table, soil type, rainfall distribution, slope, geomorphological features, drainage density, elevation and lineament density parameters are considered for the delineation of anthropogenic contamination zones based on an integrated index model in Arc-GIS. Various input layers were assigned weights and then weight normalization process was adopted using Saaty’s AHP method to develop the integrated potential anthropogenic contamination zone (PACZ) map, based on the relative importance of anthropogenic contamination of groundwater. According to the proposed model majority of the study area falls under precarious zone, though certain areas fall under safe zone. In course of time, without proper planning the area could turn out to be moderately unsafe to unsafe zone. The PACZ map was validated with the fluoride concentration in groundwater as per National Rural Drinking Water Programme (NRDWP) report along with the measured nitrate concentration values. Model accuracy was achieved by agreement of about 82% of the fluoride values and 94% of the nitrate values with the proposed output map. Further validation of the model with fluoride and nitrate data was performed using computing similarity analysis with Pearson’s correlation coefficient which suggests anomalously higher concentrations of fluoride and nitrate ion concentration in certain areas of Arang block, which could be emanated from non-point anthropogenic sources. Additionally, Gibbs’s plot and saturation indices of fluorite and calcite suggest that groundwater chemistry is primarily controlled by aquifer lithological characteristics (rock–water interaction) and diffused anthropogenic contamination sources.

Objective To detect the levels of oxidative stress in brain and serum of rats with chronic fluorosis and the antagonistic effects of vitamin E (VitE), and to reveal the role of oxidative stress in brain injury. Methods Thirty healthy SD rats were divided into three groups based on body weight by means of a random number table (10 rats in each group, half male and half female). In the control group, the rats were fed with drinking water containing less than 0.5 mg/L fluoride; in the fluoride group, the rats were fed with high doses of sodium fluoride in drinking water (50.0 mg/L) and the VitE antagonistic group were fed with the same content of fluoride in drinking water as the fluoride group, but adding VitE (50.0 mg/kg) by intragastric administration once a day. All rats were fed with normal diet (6.2 mg/kg). After exposure to fluoride for 10 months, all rats were put to death, dental fluorosis of the rats was examined and the fluoride content in bone was determined by fluoride-ion selective electrode; the activity of superoxide dismutase (SOD) was determined by the xanthine oxidase method and glutathione peroxidase (GSH-Px) by the colorimetric method, the level of malonaldehyde (MDA) by the glucosinolates barbituric acid fluorescence method and the levels of OH-, H2O2 and in rat serum and/or brain were detected by the colorimetric method. Results In the rats of the fluoride group, fluoride content in bone was higher as compared to control [bone fluoride: (211.07 ± 48.52) vs. (33.40 ± 9.26) mg/kg,P < 0.01]. The activities of SOD and GSH-Px in rat brains of the fluoride group [(20.10 ± 1.98) kU/g, (28.70 ± 19.35) kU/L] were significantly lower than those of controls [(37.05 ± 3.13) kU/g, (59.63 ± 12.83) kU/L, all P < 0.01], the activity of SOD in VitE antagonistic group [(26.27 ± 1.74) kU/g] was higher than the fluoride group (P < 0.01); the activities of SOD and GSH-Px in rat serum of the fluoride group were significantly decreased [(11.55 ± 1.75) kU/L, (79.50 ± 19.18) U/L] than those of controls [(20.79 ± 2.43) kU/L, (170.00 ± 14.68) U/L, all P < 0.01], the activity of SOD in VitE antagonistic group[(17.23 ± 0.68) kU/L] was higher than the fluoride group (P < 0.01). The levels of MDA in rat brain and serum of the fluoride group [(8.84 ± 0.69) μmol/L, (1.46 ± 0.11) nmol/L] were significantly higher than those of controls [(1.27 ± 0.74) μmol/L, (0.83 ± 0.10) nmol/L, all P < 0.01], VitE antagonistic groups [(4.51 ± 1.13) μmol/L, (1.29 ± 0.02) nmol/L] were lower than the fluoride groups (all P < 0.01). The levels of OH-, H2O2 and in rat brains of the fluoride group [(24.24 ± 1.80) kU/g, (15.28 ± 2.97) mmol/L, (6.53 ± 0.96) U/g] were significantly higher than those of controls [(11.44 ± 1.63)kU/g, (5.28 ± 1.20) mmol/L, (2.93 ± 0.42) U/g, all P < 0.01], VitE antagonistic groups [(14.43 ± 0.76) kU/g, (8.09 ± 0.55) mmol/L, (4.41 ± 0.49) U/g] were lower than the fluoride groups (all P< 0.01). Conclusions Elevated levels of oxidative stress are found in brain and serum of the rats with chronic fluorosis, which may be a main mechanism of brain injury. VitE may play an important antagonistic role in oxidative damage induced by fluoride toxicity. Key words: Fluorosis; Oxidative stress; Brain; Serum; Vitamin E

Objective To investigate the current status of coal-burning endemic fluorosis and the fluoride content in foods and drinking water in Hongya County,Sichuan Province.Methods Dental fluorosis and urinary fluoride were suveyed in children of 8～12 years old in two schools which repectively located in Gaomiao and Wawushan Town.The adults above 20 years old underwent clinical examination.At the same time,fifty adults above 20 years old in Garden Village were chosen to take forearm and calf X-ray films to find out the evidence of skeletal fluorosis.The content of fluoride in food such as bacon,corn,dry capsicum in Sanxing Village in Gaomiao Town and Futian Village in Wawushan Town as well as drinking water in five families in Sanxing Village were determined.Results The dental fluorosis rate of children was 40.76%(161/395),the dental fluorosis index was 0.86 in Gaomiao Town.The dental fluorosis rate of children was 14.36%(82/571),the dental fluorosis index was 0.31 in Wawushan Town.The medium value of the urine fluoride was 0.81 mg/L.ranged 0.16～3.89 mg/L.The positive rate oi the clinical examination of skeletal fluorosis was 5.27%(27/512),the X-rays detective rate was 4.00%(2/50).The medium value in bacon,corn,dry capsicum were 6.00,0.64,1.49 mg/kg.The averaged content of the fluoride in drinking water(0.14±0.06)mg/L of local household was within the eligible limitation.Conclusions It is currently a mild endemic disease in Hongya Country,its incidence is reduced apparently,pathogenetic environmental fluoride content is reduced.The main source of fluoride is from the preserved ham contaminated with fluoride,which is epidemiologically significant in endemic area of Hongya County.Defluoriding countermeasures should be taken in the endemic areas. Key words: Fluoride poisoning; Fluorosis,dental; X-rays; Environmental pollution

Objectives: The aims of this study were to determine the total fluoride concentration and bioavailable fluoride concentration in different toothpastes, based on a newly suggested method by the International Organization for Standardization (ISO), and to compare the measured concentrations with the concentrations written on the packaging. Methods: The concentrations of total fluoride (TF) and bioavailable fluoride (BF) were measured in six toothpastes. For the TF measurement, 1 g of each toothpaste was mixed with dipotassium hydrogen phosphate (K2HPO4), and hydrogen chloride (HCl) was placed. After 24 hours, the samples were centrifuged and total ionic strength adjustment buffer (TISAB) solution was added. For the BF measurement, the toothpaste was mixed with K2HPO4 for only 1 minute. The samples were centrifuged, and then HCl was placed and allowed to stand for 24 hours. The TISAB solution was added subsequently. The concentration of fluoride ions was measured using a fluoride ion-selective electrode and calculated against a standard curve. Results: The six toothpastes were composed of different fluoride compounds and abrasives. The measured TF concentration ranged from 624.99 ppm to 1,353.00 ppm, and the similarity to the declared fluoride concentration ranged from 53.48% to 93.31%. The measured BF concentration ranged from 587.61 ppm to 1,360.05 ppm, and the similarity to the expected fluoride concentration ranged from 41.97% to 93.80%. Two samples were clearly separated when the samples were centrifuged, whereas the remaining four samples had unclear supernatants. The clearly separated toothpastes (i.e., toothpastes 5 and 6) had BF concentrations that were similar to or lower than the declared fluoride concentrations and the measured TF concentrations. However, the unclearly separated toothpastes showed inconsistent relationships between the measured TF and BF concentrations. Conclusions: The measured TF and BF concentrations of the six toothpastes did not reach the expected fluoride concentration. This finding resulted from the different compositions and forms of the toothpastes. Therefore, the properties of toothpastes need to be considered when measuring their fluoride concentrations.

According to the World Health Organization, fluoride in drinking water, either below or above the established permissible range, can adversely affect oral health, including tooth decay and dental fluorosis. The objective of this study was to evaluate fluoride and chloride ion concentration and their health implications in groundwater within Bwari Area Council, Abuja, Nigeria using ion-selective electrode potentiometric titration for fluoride ion and Argentometric titration for chloride ion determinations. The results showed a high fluoride concentration in well water samples ranging from 0.126 mg/L to 0.216 mg/L, compared to borehole water samples ranging from 0.013 mg/mL to 0.052 mg/L. Among the chloride concentrations, the highest levels were observed in the well water sample A (96.09 mg/L), followed by borehole samples, A (63.08 mg/L) and B (49.35 mg/L). The lowest chloride concentration was recorded in the borehole sample H (11.82 mg/L). Notably, both well and borehole water sources in the studied communities had fluoride concentrations below the established minimum WHO standard (0.5 mg/L). The chloride concentrations in the groundwater samples from the study area fell within WHO standards (&lt; 250 mg/L). The results from this study suggest that the continuous consumption of water from these community sources, without additional sources of fluoride, may increase the risk of tooth decay. Therefore, addressing this issue and ensuring appropriate water treatment measures is vital for maintaining optimal oral health in the region.

Highly sensitive and rapid method for determination of fluoride ion concentrations in serum and urine using flow injection analysis with a fluoride ion-selective electrode

The objectives were to study the applicability of electrocoagulation (EC) for the denitrification of drinking water and to determine the main mechanisms of pollution removal. Electrolysis in the intensiostatic mode was applied to a synthetic water representative of potable water in which the concentration of nitrate ions was varied up to 200 mg/L. The respective influences of process parameters, initial concentration of nitrates, and initial pH were investigated. Experimental results show that EC removes efficiently nitrates, following first‐order kinetics. A two‐step mechanism was established: it consisted of the electroreduction of nitrates into ammonium on the cathode, followed by the adsorption of ammonium on the precipitated oxyhydroxides. Adsorption exhibited a zero‐order mechanism. The rates of the two mechanisms were proportional to electrical charge loading and to the total amount of aluminum released in water, as current did not modify significantly the surface area of precipitates. However, adsorption was impaired by the increase of pH resulting from the electroreduction of nitrates, whereas the electrochemical step was insensitive to pH. While the electroreduction of nitrates is known to be far more expensive than biological denitrification, aluminum hydroxides formed during EC present interesting adsorption properties for ammonium removal.

Fluoride ions are used in battery electrolytes in fluoride shuttle batteries. Since organic solvents are used in battery electrolytes, there is a growing demand to develop appropriate methods for quantifying fluoride ion concentration in organic solvents. In this study, a fluoride ion-selective electrode (ISE) for organic solutions is proposed as an electrode of the second kind. A Ag|AgF electrode was made via the anodization of a silver wire in propylene carbonate (PC) containing dissolved fluoride ions. The resultant electrode exhibits a stable linear response of the open circuit potential to the logarithm of the fluoride ion concentration in PC solutions over a range of 10-4-10-2 mol dm-3. The lower and upper limits of the linear response were interpreted in terms of the solubility and the formation of a silver fluoride complex. The use of this electrode of the second kind is suitable for the analysis of fluoride ions in organic solutions and is a promising concept for the development of ISEs for the detection of ions in organic solutions under highly restrictive conditions.

Fluoride has remained the most important ingredient in the prevention of tooth decay for many years. Therefore, fluoride prophylaxis should be highly individualized to provide patients with maximum benefits while minimizing the risk of toxic effects. This study aims to compare the degree of fluoride ion release from two commercially available dental fluoride gels (Fluormex and Fluor Protector Gel) in five different physiological solutions as well as their effect on pH. The concentration of fluoride ions and pH of tap water, distilled water, demineralized water, NaCl, and artificial saliva were evaluated before and after 48 h after dissolving and incubating the same amounts of gels. The concentration of fluoride ions was higher in solutions containing Fluormex than Fluor Pro-tector Gel (p < 0.05), with the highest concentration in demineralized water (16,917 ppm). It was accompanied by a decrease in pH below the critical value of 5.5 in all solutions except tap water. Not only the composition of the gel but also the chemical composition of the environment affects the release of fluoride ions. No relationship was found between the change in pH and the concentration of fluoride ions.

When fluoride is administered to a living body, a considerable amount is promptly absorbed, resulting in a rise in the serum fluoride concentration. This study discusses the changes in the serum total fluoride concentration and ionic fluoride concentration, as well as in the serum calcium concentration in Japanese white rabbits after fluoride administration by intubation. Rabbits were given an NaF solution containing 1, 2, 4, 6, 8 or 10 mgF/kg body weight. Blood was then taken from a marginal vein and tested. After fluoride intubation, the ionic fluoride concentration and the total fluoride concentration both rose promptly. Furthermore, the greater the fluoride dose, the more rapid the rise in serum ionic fluoride concentration and total fluoride concentration. For all fluoride treated groups, the rises in serum ionic fluoride concentration and total fluoride concentration 4 hours after administration were significantly higher than before administration.The serum ionic Calcium concentration was decreased 4 hours after fluoride administration, but later returned to normal levels (same as before administration) at 24 hours after administration. There was no significant difference in the serum total calcium concentration in all fluoride treated groups before and after fluoride administration.Serum phophorus concentration in the fluoride treated groups reached its lowest value 15 or 30 minutes after fluoride administration, but then soon returned to pre-administration values. The phosphorus concentrations at each time after administration were not significantly different from those before administration. On the other hand, blood sugar values determined within 4 hours after administration were significantly higher than those before fluoride administration. In all treated groups, however, blood sugar decreased as time passed after administration and eventually drew near to that of pre-administration values.The half-life of serum fluoride after administration was determined from the ionic fluoride concentration and total fluoride concentration. The half-life of every concentration increase proportionately to the increase in the fluoride dose.

Addressing the health concern of fluoride ions contamination in water, that cause such deceases as dental and skeletal fluorosis, requires the development of effective adsorption materials for water treatment. Our research objective was to evaluate the adsorption properties and capacities of zeolite and bentonite, sourced from Ukrainian deposits, and their acid-activated forms in relation to fluoride ions and estimate fitting this data to various adsorption models. Characterization of natural and acid-activated zeolite and bentonite sorbents was performed through X-ray diffraction to determine the phase composition of these substances. Adsorption experiments were carried out at different initial fluoride ions concentrations (3, 5, 10 and 15 mg/l) and pH (3.7; 7.5). Acidification (changing pH from 7.5 to 3.7) increase adsorption capacity of natural zeolite and bentonite more than twice. It was found that natural zeolite removes fluoride ions at the level of 67 % at pH 3.7 and a high dosage of sorbent – 10 g/l and an initial concentration of fluoride ions – 5 mg/l, while its acid‑activated form was more effective - the removal of fluoride ions is 86 % at a lower dosage of sorbent – 1 g/l. Similarly, natural bentonite demonstrated a maximum removal efficiency of 45 % at pH 3.7 and a dosage of sorbent – 10 g/l, and its acid-activated form allowed for the removal of fluoride ions of about 83 % at a dosage of sorbent – 2 g/l at the same fluoride ions concentration. It is shown that the Vagelar-Langmuir (VL) isotherm model is the most accurate for describing the process of fluoride ions adsorption by acid-activated forms of natural sorbents, where the R² values are close to 0.999, indicating monolayer adsorption on homogeneous active centers. The obtained results indicate the greater efficiency of acid-activated forms of natural sorbents and the prospects of their use for the removal of fluoride ions from water.

Objective To explore the relationships between different levels of fluoride, the global histone H3 acetylation in peripheral blood mononuclear cells (PBMC) and the condition of skeletal fluorosis, which might be helpful in explaining the mechanism of skeletal fluorosis. Methods In 2012, two counties were chosen in each area, the Tibetan living area in Guoluo of Qinghai Province and the Kazakh living area in Altay of Xinjiang Uygur Autonomous Region and 3 to 4 drinking brick-tea type fluorosis districts were chosen as the investigated districts in the counties. Totally 59 patients with skeletal fluorosis in the typical brick-tea type fluorosis districts were selected, and 59 healthy controls were selected based on age (difference ≤3 years old) and nationality. The adults were investigated by questionnaire, brick-tea water (or buttered tea), urine and 2 ml peripheral blood samples were collected, and their skeletal fluorosis was diagnosed according to the national criteria. The fluoride concentrations in brick-tea water (or Buttered tea) and urine were detected by fluoride ion selective electrode. The global histone H3 acetylation was quantified using colorimetric methord. Results The global histone H3 acetylation in PBMC between female and male population (female: 20.05 mg/g and male: 19.94 mg/g) was not significantly different (U = 1 664.5,P > 0.05). The global histone H3 acetylation in PBMC between Tibetans (17.73 mg/g) and Kazakans (20.49 mg/g) was not significantly different (U =-0.902,P > 0.05). However, global histone H3 acetylation and age was positively correlated (r =-0.213,P 3.25-8.05, > 8.05-12.33, > 12.33 mg) and global histone H3 acetylation in PBMC (21.12, 20.05, 19.94 and 35.04 mg/g,H = 1.706,P > 0.05). There was also no significant difference between urine fluoride (4 group: 0-1.69,> 1.69-2.64, > 2.64-4.00, > 4.00 mg/L) and global histone H3 acetylation in PBMC (24.42, 18.13, 19.80 and 28.90 mg/g,H = 5.928,P > 0.05). Global histone H3 acetylation in PBMC from fluorosis patients (21.69 mg/g) and control healthy subjects was similar (19.43 mg/g,Z =-1.39,P > 0.05). The difference among the different conditions of skeletal fluorosis (normal group, mild group and moderate group) was not significant (median: 19.43, 21.32 and 35.95 mg/g,H = 1.692,P > 0.05). Conclusions High fluoride exposure maybe not the factors influencing the global histone H3 acetylation in PBMC. Key words: Fluorosis, skeleton; Histone; Acetylation

Objective To explore the epidemiological situation of drinking brick-tea fluorosis in Qinhai Province.Methods According to the survey results of drinking brick-tea fluorosis in Qinghai Province in 2006,an investigation was carried out inchildren aged 8-12 in 28 counties of Qinghai Province by the method of field epidemiology in 2010.In the 28 counties,three townships and one town were selected in each county; a primary school was selected in each township (town).Fluoride content of water,brick-tea and urine was determined by using a fluoride ion-selective electrode; dental fluorosis was diagnosed by Deans method.Results In 28 counties of Qinghai Province,the mean of water fluoride concentration was 0.26 mg/L and the rang was 0-1.00 mg/L; the mean of brick-tea fluoride concentration was 1.96 mg/L and the rang was 0.14-12.59 mg/L.Chidren's geometric mean of urinary fluorine concentration was 1.14 mg/L and the rang was 0.03-9.84 mg/L; the average amount of brick-tea water drank daily by each child was (587.09 ± 237.02)ml and the rang was 0-7 000 ml; children's daily fluoride intake from brick-tea was 1.15 mg and the rang was 0-13.65 mg.Chidren's detection rate of dental fluorosis was 24.38％(3 012/12 355),and the index of dental fluorosis was 0.44.Conclusions Drinking brick-tea fluorosis of children aged 8-12 in Qinghai Province has a epidemic trend.Although the state of the disease is not serious,it is widely distributed.The intake from brick-tea water has showed an increasing trend with increasing age,we should strengthen monitoring. Key words: Child ; Brick-tea; Fluoride poisoning ; Analysis

Objectives The market for bottled water is increasing steadily in South Korea. Bottled water contains several naturally occuring minerals, such as calcium, magnesium, sodium, and fluoride. Fluoride is proven to be effective in preventing dental caries. In South Korea, the maximum permissible concentration of fluoride is 2 ppm for bottled water and 1.5 ppm for tap water. The aim of this study was to investigate the fluoride content of different commercially available brands of bottled water in South Korea, and compare the measured fluoride concentration to the concentration written on the label of each brand of bottled water. Methods Twenty-seven of the 59 different brands of bottled water produced in South Korea were investigated in this study. Three bottles of each brand were purchased from supermarkets, marts, and convenience stores in each region of Korea in August 2016. For each bottled water brand, the fluoride content was measured three times using a fluoride-ion selective electrode (Orion ionplus Fluoride Electrode 9609, Orion Research, USA). The calibration curve was generated using 0.2 and 2 ppm standard solutions, and confirmed using a 1 ppm standard solution. Results The mean fluoride content of the 27 brands of bottled water was 0.374±0.332 mg/L (range=0.040 to 1.172 mg/L). The fluoride content was labeled by the manufacturer, on each of the tested brands of bottled water. In eight brands, the labeled fluoride content differed from the experimental data. The minimum to maximum fluoride content measured from 10 brands showed a variation of 0.3 mg/L or more when compared to the labeled fluoride content. Conclusions This study investigated the fluoride content of various brands of bottled water produced in South Korea and compared the measured fluoride levels with fluoride information on the bottle labels. To ensure that consumers are suitably informed regarding their exposure to fluoride, correct labelling of fluoride content in bottled water is important.