Fluorine In Water Research Articles

The Effect of Water Fluoride Concentration on DMFT Index in Vardar Population in Macedonia

The aim of this study is to determine the correlation between the DMFT index of 12-year-old children and the concentration of fluorine in drinking water from the populated areas where children live. Material and method: In the examination, 85children were enrolled, out of 2 central and 2regional primary schools, at which the DMFT index was determined. The children live in 2 different cities and 2 different villages. Four water samples were taken from the examined area to determine the fluorine concentration by using the electrochemical method using the pH/ISE Meter-Thermo-Orion with a special F-electrode (Thermo Orion Ion Plus Fluoride Electrode) at the Institute for public health. Spearman's method was used to determine the correlation between the specified variables. Results: The total number of children in the examined sample was 85, out of which45 were male and 40 were female. The average DMFT index in this group of children was 2.75 with a standard deviation of ±2.56. Maximum concentration of fluorine in drinking water of 0.39ppmF was determined in the village Vinicani, while the minimum (0.17ppmF) in the city Veles and (0.20 ppmF) in the village Melnica. Correlation of the DMFT index in children from the Vardar region and the concentration of fluorine in the drinking water has a negative, indirect correlation, with the value of the coefficient r=-0.393. Conclusion: The correlation between the DMFT index and the concentration of drinking water is a negative, indirect and correlation is highly significant.

The Effect of Water Fluoride Concentration on DMFT Index in Vardar Population in Macedonia

The aim of this study is to determine the correlation between the DMFT index of 12-year-old children and the concentration of fluorine in drinking water from the populated areas where children live. Material and method: In the examination, 85children were enrolled, out of 2 central and 2regional primary schools, at which the DMFT index was determined. The children live in 2 different cities and 2 different villages. Four water samples were taken from the examined area to determine the fluorine concentration by using the electrochemical method using the pH/ISE Meter-Thermo-Orion with a special F-electrode (Thermo Orion Ion Plus Fluoride Electrode) at the Institute for public health. Spearman's method was used to determine the correlation between the specified variables. Results: The total number of children in the examined sample was 85, out of which45 were male and 40 were female. The average DMFT index in this group of children was 2.75 with a standard deviation of ±2.56. Maximum concentration of fluorine in drinking water of 0.39ppmF was determined in the village Vinicani, while the minimum (0.17ppmF) in the city Veles and (0.20 ppmF) in the village Melnica. Correlation of the DMFT index in children from the Vardar region and the concentration of fluorine in the drinking water has a negative, indirect correlation, with the value of the coefficient r=-0.393. Conclusion: The correlation between the DMFT index and the concentration of drinking water is a negative, indirect and correlation is highly significant.

The Effect of Water Fluoride Concentration on DMFT Index in Vardar Population in Macedonia

The aim of this study is to determine the correlation between the DMFT index of 12-year-old children and the concentration of fluorine in drinking water from the populated areas where children live. Material and method: In the examination, 85children were enrolled, out of 2 central and 2regional primary schools, at which the DMFT index was determined. The children live in 2 different cities and 2 different villages. Four water samples were taken from the examined area to determine the fluorine concentration by using the electrochemical method using the pH/ISE Meter-Thermo-Orion with a special F-electrode (Thermo Orion Ion Plus Fluoride Electrode) at the Institute for public health. Spearman's method was used to determine the correlation between the specified variables. Results: The total number of children in the examined sample was 85, out of which45 were male and 40 were female. The average DMFT index in this group of children was 2.75 with a standard deviation of ±2.56. Maximum concentration of fluorine in drinking water of 0.39ppmF was determined in the village Vinicani, while the minimum (0.17ppmF) in the city Veles and (0.20 ppmF) in the village Melnica. Correlation of the DMFT index in children from the Vardar region and the concentration of fluorine in the drinking water has a negative, indirect correlation, with the value of the coefficient r=-0.393. Conclusion: The correlation between the DMFT index and the concentration of drinking water is a negative, indirect and correlation is highly significant

The Effect of Water Fluoride Concentration on DMFT Index in Vardar Population in Macedonia

The aim of this study is to determine the correlation between the DMFT index of 12-year-old children and the concentration of fluorine in drinking water from the populated areas where children live. Material and method: In the examination, 85children were enrolled, out of 2 central and 2regional primary schools, at which the DMFT index was determined. The children live in 2 different cities and 2 different villages. Four water samples were taken from the examined area to determine the fluorine concentration by using the electrochemical method using the pH/ISE Meter-Thermo-Orion with a special F-electrode (Thermo Orion Ion Plus Fluoride Electrode) at the Institute for public health. Spearmans method was used to determine the correlation between the specified variables. Results: The total number of children in the examined sample was 85, out of which45 were male and 40 were female. The average DMFT index in this group of children was 2.75 with a standard deviation of ±2.56. Maximum concentration of fluorine in drinking water of 0.39ppmF was determined in the village Vinicani, while the minimum (0.17ppmF) in the city Veles and (0.20 ppmF) in the village Melnica. Correlation of the DMFT index in children from the Vardar region and the concentration of fluorine in the drinking water has a negative, indirect correlation, with the value of the coefficient r=-0.393. Conclusion: The correlation between the DMFT index and the concentration of drinking water is a negative, indirect and correlation is highly significant

The Effect of Water Fluoride Concentration on DMFT Index in Vardar Population in Macedonia

The aim of this study is to determine the correlation between the DMFT index of 12-year-old children and the concentration of fluorine in drinking water from the populated areas where children live. Material and method: In the examination, 85children were enrolled, out of 2 central and 2regional primary schools, at which the DMFT index was determined. The children live in 2 different cities and 2 different villages. Four water samples were taken from the examined area to determine the fluorine concentration by using the electrochemical method using the pH/ISE Meter-Thermo-Orion with a special F-electrode (Thermo Orion Ion Plus Fluoride Electrode) at the Institute for public health. Spearman's method was used to determine the correlation between the specified variables. Results: The total number of children in the examined sample was 85, out of which45 were male and 40 were female. The average DMFT index in this group of children was 2.75 with a standard deviation of ±2.56. Maximum concentration of fluorine in drinking water of 0.39ppmF was determined in the village Vinicani, while the minimum (0.17ppmF) in the city Veles and (0.20 ppmF) in the village Melnica. Correlation of the DMFT index in children from the Vardar region and the concentration of fluorine in the drinking water has a negative, indirect correlation, with the value of the coefficient r=-0.393. Conclusion: The correlation between the DMFT index and the concentration of drinking water is a negative, indirect and correlation is highly significant

Study of the fluorine adsorption onto zirconium oxide deposited strong alkaline anion exchange fiber

ABSTRACTA kind of adsorbent, strong alkaline anion exchange fiber loaded with zirconium strong alkaline anion exchange fiber (Zr@SAAEF) was prepared. Zr(IV) was uniformly distributed on SAAEF through chemical bonds and physical deposition. Zr@SAAEF has a decent effect on the removal of fluorine in water and scanning electron microscopy images and Fourier transform infrared spectroscopy spectrum showed that the Zr(IV) was successfully loaded on the fiber by chemical bonding. The average adsorption capacity of fluorine was 28.14 mg/g with pH ranging from 5.0 to 8.9, when fluorine solution (100 mg/L) was adsorbed by 0.1 g SAAEF, and the extent of removal exceed 96% when the adsorbent dose was 0.3 g. The adsorption isotherms were well fitted with Langmuir equation, and the maximum adsorption capacities calculated by Langmuir equation were close to the experiment results. The adsorption was an endothermic reaction. These results implied that fluorine adsorption onto Zr@SAAEF belonged to chemical adsorption using monolayer coverage on surface of the fiber. The adsorption kinetics of fluorine onto Zr@SAAEF could be described by pseudo‐second‐order rate mode. Zr@SAAEF showed a decent ability for fluorine removal from aqueous solution. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45855.

Determination of fluorine in herbs and water samples by molecular absorption spectrometry after preconcentration on nano-TiO2 using ultrasound-assisted dispersive micro solid phase extraction

This work presents ultrasound-assisted dispersive micro solid phase extraction (USA DMSPE) for preconcentration of fluorine (F) in water and herb samples. TiO2 nanoparticles (NPs) were used as an adsorbent. The determination with slurry sampling was performed via molecular absorption of calcium monofluoride (CaF) at 606.440 nm using a high-resolution continuum source electrothermal absorption spectrometry (HR-CS ET MAS). Several factors influencing the efficiency of the preconcentration technique, such as the amount of TiO2, pH of sample solution, ultrasonication and centrifugation time and TiO2 slurry solution preparation before injection to HR-CS ET MAS, were investigated in detail. The conditions of detection step (wavelength, calcium amount, pyrolysis and molecule-forming temperatures) were also studied. After extraction, adsorbent with the analyte was mixed with 200 μL of H2O to prepare a slurry solution. The concentration limit of detection was 0.13 ng mL−1. The achieved preconcentration factor was 7. The relative standard deviations (RSDs, %) for F in real samples were 3–15%. The accuracy of this method was evaluated by analyses of certified reference materials after spiking: INCT-MPH-2 (Mixed Polish Herbs), INCT-SBF-4 (Soya Bean Flour), ERM-CAO11b (Hard Drinking Water) and TMDA-54.5 (Lake Ontario Water). The measured F contents in reference materials were in satisfactory agreement with the added amounts, and the recoveries were found to be 97–109%. Under the developed extraction conditions, the proposed method has been successfully applied for the determination of F in real water samples (lake, sea, tap water) and herbs.

Distribution and Potential Health Risks of Arsenic, Selenium, and Fluorine in Natural Waters in Tibet, China

The contents of major and trace elements were analyzed in 204 different types of water samples in 138 villages across 51 counties and cities of Tibet. The average concentrations of arsenic (As), selenium, and fluorine for each water category decreased in the following order: arsenic (in μg/L: hot spring 241.37 > lake 27.46 > stream 22.11 > shallow well 11.57 > deep well 6.22), selenium (in μg/L: deep well 0.85 > shallow well 0.68 > stream 0.62 > hot spring 0.39 > lake 0.36), and fluorine (in mg/L: hot spring 2.10 > lake 1.06 > deep well 0.45 > stream 0.20 > shallow well 0.15). The distribution of arsenic in Tibetan waters ranged between 77.35 μg/L in Ali prefecture and 1.17 μg/L in Chamdo prefecture, with intermediate values of 4.39, 2.52, 2.10, 1.68, and 1.51 μg/L in the prefectures of Shigatse, Nagchu, Lhasa, Lhoka, and Nyingchi, respectively. Carbonatite is a major source of elements in these waters. The non-carcinogenic risk in Tibet caused by heavy metals in drinking water is low overall, except in Ali prefecture’s surface and shallow ground waters, which contain high levels of As. Thus, deep well water in Tibet is safe to drink.

Reuse Research Progress on Waste Clay Brick

Waste clay brick (WCB) is silicate solid waste, its recycling has great environmental and social significance. The application of WCB as recyclable coarce and fine aggregate in concrete and mortar, wall materials, as well as raw material or addition in the production of recyclable cement, has been briefly introduced. The following aspects were emphasized: the research progress of the impact of WCB as supplementary cementitious material on physical mechanics, deformation and durability of cementitious materials; the progress of the function of WCB as environmental materials on eliminating fluorine, ammonia nitrogen and phosphate in waste water; the current research status of the impact of WCB as recyclable aggregate on the mechanics, durability of GRC; the current status of WCB as filler in decorative paints, as filler in rubber plastic materials after being organically modified, as well as in the production of recyclable ancient architectural brick in recent years. The problems in recycling of WCB has also been summarized.

Influence of the Synthesis Parameters on the Properties of NaYF4:Yb3+,Tm3+ Nanoparticles.

Fluorescent nanoparticles, especially fluorides, have received a great deal of interest due to their optical properties, making them suitable for applications in bio-imaging. For this reason they need to exhibit a superior chemical stability in aqueous media. We have studied the influence of the synthesis parameters on the chemical stability of NaYF(4) nanoparticles co-doped with Yb(3+) and Tm(3+). These nanoparticles have different crystal structures, and were synthesized hydrothermally or with thermal decomposition. The samples were characterized with X-ray diffraction and transmission electron microscopy. The up-conversion fluorescence of nanoparticles dispersed in water was measured at 400-900 nm. The partial dissolution of the fluorine in water was detected with an ion-selective electrode for all the samples. The dissolution of the other constituent ions was analysed with an optical emission spectrometer using inductively coupled plasma. The nanoparticles with a hexagonal crystal structure and sizes of around 20 nm that were synthesized with thermal decomposition showed a superior chemical stability in water together with a superior up-conversion fluorescence yield.

Arsenic and fluorine in groundwater in western Jilin Province, China: occurrence and health risk assessment

In this paper, the triangular fuzzy numbers theory is introduced to health risk assessment. On the basis of defining the parameters as triangular fuzzy numbers, uncertain models were established. As a case study, the fuzzy models were applied to evaluate the health risk of arsenic and fluorine in groundwater in western Jilin Province. The evaluation results indicated that there was great carcinogenic risk of arsenic in Quaternary phreatic water, Quaternary confined water, and Tertiary confined water, and the most probable risk values were 20.94 × 10−5, 55.22 × 10−5, and 24.02 × 10−5 a−1, respectively; all of these values are greater than 5.0 × 10−5 a−1, the acceptable maximum value recommended by the International Agency for Research on Cancer (IARC). The most probable risk values of fluorine in Quaternary phreatic water, Quaternary confined water, and Tertiary confined water were 3.64 × 10−8, 2.48 × 10−8, and 2.17 × 10−8 a−1, respectively, all of which are less than the acceptable maximum value recommended by IARC. The assessment results showed that groundwater in the study area posed great health risks, and the fuzzy models reveal the health risk state of hazardous substances in groundwater more scientifically than traditional models.

Fluorine in surface and subsoil waters in the Middle Klyaz’ma Basin

Data on fluorine concentration in water in the Middle Klyaz’ma Basin during summer low-water period have been obtained. Fluorine background concentration has been determined in streams (Klyaz’ma R., small rivers, and creeks), water bodies (drainage ditches, lakes), and subsoil waters. Anthropogenic fluorine hydrochemical anomalies have been determined and localized with respect to urbanized industrial areas. An assumption has been made and experimentally substantiated, according to which fluorine concentration in subsoil water is governed by the processes of its distribution between water and host rocks. It has been established that the interaction of soils with snowmelt water and alluvial deposits with river water in neutral and acid media is accompanied by fluorine removal from solution, while in a weakly alkaline medium, fluorine passes from solid phase into solution. The effect of dissolved organic matter on the process of fluorine leaching from rock minerals also depends, primarily, on the equilibrium pH value: in weakly alkaline media, the presence of organic acids contributes to fluorine mobilization, while in weakly acid media, it reduces mobilization rate.

Determination of fluorine in milk and water via molecular absorption of barium monofluoride by high-resolution continuum source atomic absorption spectrometer

This study describes the determination of fluorine evaluating the molecular absorption of barium monofluoride (BaF) at the rotational lines of 495.088 and 495.263nm simultaneously using a high-resolution continuum source electrothermal atomic absorption spectrometer. Upon pipetting of samples together with Ba as its nitrate, BaF was generated in the gas-phase of the atomizer. All experiments were performed using pyrolytically coated graphite tubes/platforms and applying 900°C for pyrolysis and 2200°C for vaporization. In the presence of 50μg of Ba, a perfect linearity up to 0.1μg of F was maintained. The limit of detection and characteristic mass of the method were 0.105ng and 0.055ng of F, respectively. The F concentration of a standard waste water sample was found in the uncertainty limits of its certified value as well as spike additions were quantitatively recovered. Finally, F concentrations in various water and milk samples sold in markets were determined.

Determination of adsorbable organic fluorine from aqueous environmental samples by adsorption to polystyrene-divinylbenzene based activated carbon and combustion ion chromatography

A new method for the determination of trace levels of adsorbable organic fluorine (AOF) in water is presented. Even if the individual contributing target compounds are widely unknown, this surrogate parameter is suited to identify typical organofluorine contaminations, such as with polyfluorinated chemicals (PFCs), and represents a lower boundary of the organofluorine concentration in water bodies. It consists of the adsorption of organofluorine chemicals on a commercially available synthetic polystyrene-divinylbenzene based activated carbon (AC) followed by analysis of the loaded AC by hydropyrolysis combustion ion chromatography (CIC). Inorganic fluorine is displaced by excess nitrate during the extraction step and by washing the loaded activated carbon with an acidic sodium nitrate solution. Due to its high purity the synthetic AC had a very low and reproducible fluorine blank (0.3μg/g) compared to natural ACs (up to approximately 9μg/g). Using this AC, fluoride and the internal standard phosphate could be detected free of chromatographic interferences. With a sample volume of 100mL and 2× 100mg of AC packed into two extraction columns combined in series, a limit of quantification (LOQ), derived according to the German standard method DIN 32645, of 0.3μg/L was achieved. The recoveries of six model PFCs were determined from tap water and a municipal wastewater treatment plant (WWTP) effluent. Except for the extremely polar perfluoroacetic acid (recovery of approximately 10%) the model substances showed fairly good (50% for perfluorobutanoic acid (PFBA)) to very good fluorine recoveries (100±20% for perfluorooctanoic acid (PFOA), perfluorobutanesulfonate (PFBS), 6:2 fluorotelomersulfonate (6:2 FTS)), both from tap water and wastewater matrix. This new analytical protocol was exemplarily applied to several surface water and groundwater samples. The obtained AOF values were compared to the fluorine content of 19 target PFCs analyzed by high performance liquid chromatography–electrospray tandem mass spectrometry (HPLC–(−)ESI-MS/MS). In groundwater contaminated by PFC-containing aqueous film-forming foams (AFFFs) up to 50% of the AOF could be attributed to PFC target chemicals, while in diffuse contaminated samples only <5% of the AOF could be identified by PFC analysis.

Origin of fluorine in mineral waters of Bujanovac valley (Serbia, Europe)

This paper deals with mineral and thermomineral water occurrences of the Bujanovac valley in south eastern part of Serbia related to granitoides of the Bujanovac massif along both the margin and the floor of the valley. In past decades (1966–2010) numerous hydrogeological, hydrogeochemical and geophysical explorations were carried out. One of results of these explorations is the completion of test holes and exploratory—production wells. They provide groundwater for three water bottling factories: “Heba”, “Bivoda”, “Prohor” as well as the “Vrelo Bujanovac Banja Spa Centre” for rehabilitation, treatment, and prevention. All stated consumers use the same mineral water aquifer. The content of fluoride in the majority of examined mineral waters is higher than 4 mg/1, whereby they are singled out as typical fluoride waters. The content of calcium ions in them amounts 80 mg/1, and the values of the saturation index in relation to calcium fluoride (SI) range from 0.4 to 0.7 mg/1, which points to mineral waters saturated in relation to fluorite. However, in the study area, there are mineral water occurrences with the content of fluoride significantly lower than in the majority of analysed waters representing hydrochemical anomalies. These waters occur as hydrochemical anomalies in marl and sandstone wherein Secondary mineral water aquifers, originating from cracked granite of the Bujanovac massif, are formed. When mineral waters from granite (with the increased content of fluoride) reach these secondary aquifers, the content of fluoride ions lowers to about 1 mg/1, which is of great significance from the point of view of mineral water utilisation as table bottled water. In this paper, it is proved that, in addition to the presence of some minerals as basic fluorine bearers, the role of the lithological environment where the natural process of defluoridation occurs is significant, which is confirmed by the revitalization of the A-4 well. The paper deals with mineral water deposits of the Bujanovac valley, and the natural way of lowering of fluorine content in the given waters.

Analysis of endemic fluorosis of Xinbaerhuyouqi in Hulunbeir city of Inner Mongolia in 2000 - 2009

Objective To investigate the dynamics and development trends of drinking water type of endemic fluorosis after water improvement in Xinbaerhuyouqi of Hulunbeir city, Inner Mongolia and to provide a scientific evidence for the development of countermeasures. Methods We mainly selected Adunchulusumu and Kerlunsumu in Xinbaerhuyouqi of Hulunbeir city as the two monitoring points after water improvement in 2000 -2009. Of these, 1 sample of centralized water supply source water and 3 samples of tap water and 5 samples of noncentralized water supply source water according to water well locations of east, west, south, north and center were collected and the levels of water fluoride were tested; the prevalence of dental fluorosis of school children aged 8 to 12 were examined; from 2002 onwards, the urine samples of 30 children aged 8 to 12(five age groups, six urine samples for each age group) were collected, and all urine samples were collected in the case of less than 30, and urine fluoride was tested. Dental fluorosis was diagnosed using Dean method; water fluoride was tested using fluoride ion selective electrode(WS/T 106-1999); urinary fluoride was tested by determination of fluoride in urine using ion-selective electrode(WS/T 89-1996). Results In 2000 - 2009, the mean levels of fluorine in drinking water in Adunchulusumu and Kerlunsumu were 1.79 - 4.35 mg/L and 1.38 - 3.18 mg/L, respectively; the detection rate of dental fluorosis of children aged 8 to 12 were 45.24％(19/42) - 89.78％(123/137) and 40.00％ (28/70) - 74.47％ (70/94), respectively; the median urinary fluoride of them were 2.30 - 4.15 mg/L and 2.73 - 4.55 mg/L, respectively. Conclusions The detection rate of children's dental fluorosis remains high in Xinbaerhuyouqi during the past 10 years after changing water. The endemic fluorosis remains a serious disease. Effective prevention and control measures must be taken to control the occurrence of fluorosis in the future. Key words: Fluoride poisoning; Drinking; Urine; Fluorosis, dental

Analysis of surveillance results of drinking water type of endemic fluorosis in Qinghai province in 2009

Objective To investigate the development trend of drinking water type of endemic fluorosis in Qinghai province, and to provide the basis for the prevention and treatment of the disease. Methods In 2009, six monitoring counties were chosen by using simple random sampling methods, all diseased villages of the six monitoring counties were classified into light, moderate and severe disease types according to water fluorine content on the historical data, and 1 village was respectively chosen from each type. In monitoring villages with improved water, 3 tap water and one source water samples were collected, respectively. Five water samples were collected randomly in water unimproved monitoring villages according to water well locations of east, west, south, north and center. The fluorine content in water and urine was determined according to the Standard Testing Methods for Drinking Water (GB/T 5750-2006). Children aged 8 to 12 were examined for dental fluorosis by Dean method.Clinical osteofluorosis of all the resident over the age of 16 was examined, 2 village of these counties were randomly selected, and clinically diagnosed patients with skeletal fluorosis were examined again by X-ray using Diagnostic Criteria of Endemic Skeletal Fluorosis (WS 192-2008). Urine sample of 30 children aged 8 to 12 and of 20 adults over the age of 16 were randomly collected and urinary fluoride was determined by F-ion selective electrode method (WS/T 89-2006). Results Improving water projects had been implemented in 14 monitoring villages of the 18 villages in 6 counties, the rate of improved-water was 77.78％(14/18). Among the 14 projects, 5 improved-water projects ran normally, and 9 projects ran with intermittently water supply. Seventy-five water samples were tested, themean of water fluoride was 0.48 mg/L. The prevalence of dental fluorosis was 31.95％ (285/892), that of clinical skeletal fluorosis was 36.55％(1570/4295) and the X-ray detection rate of skeletal fluorosis was 25.64％ (20/78).Five hundred and seventy-one urine samples of children were determined, and geometric mean of urinary fluorine was 1.04 mg/L; 370 adult urine samples were determined, and geometric mean of urinary fluorine was 1.52 mg/L Conclusion Epidemic of drinking water type of endemic fluorosis is still serious in Qinghai province, and drinking water defluoride measures should be further strengthened and improved. Key words: Fluoride poisoning; Fluorosis, dental; Osteofluorosis; Data collection

Endemic fluorosis in Jilin province: analysis of surveillance data for 2006 - 2010

Objective To identify changes in the occurrence of endemic fluorosis in order to provide scientific basis for making countermeasures. Methods Five villages from 14 counties of mild, moderate and severe fluorosis affected areas were selected by stratified cluster sampling every year in the whole province during 2006 - 2010. Water and urinary fluorine were determined by ion selective electrode method(GB/T 8538-1995); dental fluorosis of children 8-12 years old was diagnosed with Dean method; skeletal fluorosis was diagnosed according to clinical indexing standards of endemic skeletal fluorosis (GB 16396-1996), between 2006 and 2008, and clinical diagnosis standard of endemic skeletal fluorosis(WS 192-2008) between 2009 and 2010. Results A total of 25 diseased villages were surveyed, 14 with water sources changed, covered a resident population of 8005 people, beneficiary population 7154, and accounting for 89.37% of the resident population; not changed villages 11. In accordance with the State drinking water health standards, in the 14 changed villages the fluoride in drinking water was qualified (≤ 1.20 mg/L), there were 3 schools whose water fluorine content exceeded the standard; among the 11 villages that did not change water sources 7 drinking water samples fluorine content exceeded the standard. Of the 8 to 12 years old children in villages with changed water sources, 363 of them were checked and 142 dental fluorosis were found, the detection rate of dental fluorosis was 39.12% (142/363); in villages with water sources not changed, 303 children were checked, the detection rate of dental fluorosis was 43.89%(133/303). Of sixteen and elder adults in water source changed villages, 6424 people were checked and 403 skeletal fluorosis were found, skeletal fluorosis detection rate was 6.27% (403/6424); 3572 people were checked in not changed villages, the detection rate of skeletal fluorosis was 13.89%(496/3572). In water sources changed areas, geometric mean of urinary fluoride was in the normal reference value(WS/T 256-2005, 1.40 mg/L)or less. Conclusions Endemic fluorosis is decreased in water improved areas, but in unimproved areas the disease is still severe, and control of endemic fluorosis is still an arduous task. Key words: Endemic diseases; Fluorosis, dental; Osteofluorosis

Geochemistry and health aspects of F-rich mountainous streams and groundwaters from sierras Pampeanas de Cordoba, Argentina

Symptoms of dental fluorosis have been observed in rural communities located in the Sierras Pampeanas de Cordoba, a mountainous area in Central Argentina. The clinical assessment was performed in the Charbonier Department, where the fluoride (F−) intake was determined to be 3.90 ± 0.20 mg day−1 (n = 16). In this community, mild and severe fluorosis reach an incidence of 86.7% (total teeth surface = 636 teeth) among the children population. To determine the origin and distribution of fluorine in natural waters from the Charbonier Department and nearby regions, sampling was performed in the area covering the San Marcos River basin. The obtained results show that F− concentrations vary between ~1 to ~2.5 mg l−1, with an outlier value of 8 mg l−1. The spatial distribution of F− shows that the lowest concentrations are found at the basin’s catchments. Maximum values are located in two sectors of the basin: the Charbonier depression in the eastern part and at the San Marcos village, downstream the main collector, in the western part of the basin. In these two regions, the F− contents in ground- and surface waters are >2.0 mg l−1 and nearly constant. Dissolved F− in natural waters from the study area has its origin in the weathering of F-bearing minerals present in the region’s dominant lithology. The extent of mineral weathering is mostly determined by the residence time of water within the aquatic reservoir. Longer residence times and a major solid–water interaction lead to enhanced release of F−. This explains the higher F− concentrations found in basin areas with lower run off. The removal of F− from water appears to occur by neither fluorite precipitation, nor by adsorption. Hence, variations in F− concentrations seem to be more related to regional hydrological conditions.

Fluorine in Water and Dental Fluorosis in a Community of Queretaro State Mexico

The community La Llave, Queretaro State, Mexico, has not been identified by the sanitary authorities as living in a hazard area related to dental fluorosis. However; a high concentration of fluoride is found in their drinking water causing them dental fluorosis. Physical-chemical analysis was carried out in the groundwater sources to determine the prevalence of dental fluorosis risk and caries accordingly to criteria of The World Health Organization, and 154 school children of ages 10 to 13 years were examined. As a result, 1.9 mg/L of fluorine concentration in drinking water was obtained; dental fluorosis presence was detected in the school children with an incidence of about 98%, in 47% of cases severe fluorosis with a dental caries index of 3.06 was traced. The groundwater sources in La Llave community contains fluorine above the limits dictated by Mexican regulations, producing serious repercussions on the health of school children, with an unnaturally high incidence of dental fluorosis.