Fluoride Concentration In Water Research Articles

Fluoride exposure and hypothyroidism in a Canadian pregnancy cohort

BackgroundWhile fluoride can have thyroid-disrupting effects, associations between low-level fluoride exposure and thyroid conditions remain unclear, especially during pregnancy when insufficient thyroid hormones can adversely impact offspring development. ObjectivesWe evaluated associations between fluoride exposure and hypothyroidism in a Canadian pregnancy cohort. MethodsWe measured fluoride concentrations in drinking water and three dilution-corrected urine samples and estimated fluoride intake based on self-reported beverage consumption. We classified women enrolled in the Maternal-Infant Research on Environmental Chemicals Study as euthyroid (n = 1301), subclinical hypothyroid (n = 100) or primary hypothyroid (n = 107) based on their thyroid hormone levels in trimester one. We used multinomial logistic regression to estimate the association between fluoride exposure and classification of either subclinical or primary hypothyroidism and considered maternal thyroid peroxidase antibody (TPOAb) status, a marker of autoimmune hypothyroidism, as an effect modifier. In a subsample of 466 mother-child pairs, we used linear regression to explore the association between maternal hypothyroidism and child Full-Scale IQ (FSIQ) at ages 3-to-4 years and tested for effect modification by child sex. ResultsA 0.5 mg/L increase in drinking water fluoride concentration was associated with a 1.65 (95 % confidence interval [CI]: 1.04, 2.60) increased odds of primary hypothyroidism. In contrast, we did not find a significant association between urinary fluoride (adjusted odds ratio [aOR]: 1.00; 95%CI: 0.73, 1.39) or fluoride intake (aOR: 1.25; 95%CI: 0.99, 1.57) and hypothyroidism. Among women with normal TPOAb levels, the risk of primary hypothyroidism increased with both increasing water fluoride and fluoride intake (aOR water fluoride concentration: 2.85; 95%CI: 1.25, 6.50; aOR fluoride intake: 1.75; 95%CI: 1.27, 2.41). Children born to women with primary hypothyroidism had lower FSIQ scores compared to children of euthyroid women, especially among boys (B coefficient: −8.42; 95 % CI: −15.33, −1.50). DiscussionFluoride in drinking water was associated with increased risk of hypothyroidism in pregnant women. Thyroid disruption may contribute to developmental neurotoxicity of fluoride.

Application Progress of New Adsorption Materials for Removing Fluorine from Water

A large amount of fluorine−containing wastewater was produced with the rapid development of the industry. Excessive fluoride content in water will not only endanger ecological security but also pose threat to human health. In this study, common new adsorbents for defluorination, such as metal−based adsorbents, natural adsorbents, and nanomaterial adsorbents were reviewed for its physicochemical properties and fluorine removal efficiency. The fluorine removal mechanism of different adsorbents was introduced in detail, and the future work of the removal of fluorine using novel adsorbents was proposed. This research also introduces the application of the coupling of the adsorption method with the technology of chemical precipitation, filtration, and super−magnetic separation to treat high concentration of fluoride wastewater. A good selection of process combinations according to different needs can achieve high−efficiency defluorination in water. Finally, some existing problems of practical operation of fluorine using removal materials in the environment are summarized, hoping to contribute to the future research of fluorine removal materials.

Coal mine waste characterization and defluoridation property

Fluoride contamination has been addressed as a major problem worldwide, along with the scarcity of water. This attracts researchers to do more research in the field of fluoride contamination and mitigation of high fluoride content in water. There are various studies, that used a variety of adsorbents for the removal of fluoride from contaminated water. But none of them utilized the vast number of waste, that is generated from the coal mining industries. In this paper, Shale, which is a common coal mine waste, has been used as an adsorbent for fluoride removal from aqueous solution. Along with the defluoridation property of shale, the effect of weathering on the adsorption property of shale was also analyzed using different characterization tests, such as XRD (X-ray powder diffraction), SEM (Scanning Electron Microscope), and FTIR (Fourier Transform Infrared spectroscopy). Two types of shale samples were collected, crushed, and used in the adsorption process in the lab using synthetic fluoride solution. The maximum efficiency of type I (weathered) shale was obtained as 47.05% compared to type II (fresh) shale as 40.02% for 3 ppm initial fluoride solution for 60 min of contact time in pH range 5–7 using batch adsorption process. Other parameters such as shale particle size, pH, and total suspended solid present before and after the adsorption process were also taken into consideration. The adsorption followed pseudo-second kinetics and Freundlich isotherm with an adsorption capacity of 23.66 mg/g, and 21.33 mg/g for weathered and fresh shale respectively. The characterization test showed more clayey content in the weathered shale compared to fresh shale, making it more porous and suitable as a fluoride adsorbent. XRD showed the F− containing minerals such as Villiaumite (5.1%) and Fluorite (4.3%) in F− loaded weathered shale, confirming the F− adsorption onto the shale surface. The major advantage of shale over other existing adsorbents is, it removes the fluoride without significant change in pH, and there are no or very less suspended ions that can be found in treated water. This means the water may not need any secondary treatment after the adsorption process. Shale is a very common and readily available mine waste, that is used for the ceramic industry, building materials, and road construction, making it a no-cost material to be used as an adsorbent for fluoride removal.

Association between dental fluorosis prevalence and inflammation levels in school-aged children with low-to-moderate fluoride exposure

Inflammation mediates the neurological deficits caused by fluoride. Thus, whether inflammation is the underlying mechanism of dental fluorosis (DF) in school-aged children is worth exploring. A cross-sectional study was conducted to investigate the association between inflammation and the prevalence and severity of DF with low-to-moderate fluoride exposure. Fasting morning urine and venous blood samples were collected from 593 children aged 7–14 years. The fluoride content in the water and urine samples was measured using a fluoride ion-selective electrode assay. The levels of interleukin-1β (IL-1β) and C-reactive protein (CRP) were detected using an enzyme-linked immunosorbent assay. The Dean's index was used when performing dental examinations. Regression, stratified, and mediation analyses were performed to analyze the association between fluoride exposure, inflammation, and DF prevalence. In the adjusted regression models, the prevalence of mild DF was 1.723-fold (95% confidence interval [CI]:1.612, 1.841) and 1.594-fold (1.479, 1.717) greater than that of normal DF for each 1 mg/L increase in water and urinary fluoride content, respectively. The prevalence of mild DF increased by 3.3% for each 1 pg/mL increase in the IL-1β level and by 26.0% for each 1 mg/L increase in the CRP level. Stratified analysis indicated a weaker association between fluoride concentration and DF prevalence in boys than in girls, and susceptibility in the boys was reflected by the association of IL-1β with very mild and moderate DF prevalence. For every 1 mg/L increase in water and urinary fluoride levels, the proportion of IL-1β-mediated effects on the prevalence of mild DF was 10.0% (6.1%, 15.8%) and 8.7% (4.8%, 15.2%), respectively, and the proportion of CRP-mediated effects was 9.2% (5.5%, 14.9%) and 6.1% (3.3%, 11.0%), respectively. This study indicates that the DF prevalence may be sex-specific. Inflammatory factors may partially mediate the increased prevalence of mild DF in school-aged children with low-to-moderate fluoride exposure.

Level of natural fluoride in public water supply: geographical and meteorological factors in Brazil's Northeast.

This study analyzed the relationships between the concentration of natural fluoride in public water supply and meteorological and hydrographic factors in a northeastern region of Brazil. This was a descriptive, analytical, ecological, longitudinal, and field study conducted by collecting water in 23 municipalities (2019 to 2020) of four macroregions of Paraíba (Brazil): coast (1), borborema (2), agreste (3), and outback (4). Four collection sites were selected per municipality: two near and two distant from the water treatment plant. Fluoride concentration was determined using a combined ion-specific electrode and classified according to the Collaborating Center of the Ministry of Health in Oral Health Surveillance. Meteorological, hydrographic, and population characteristics were also collected. All analyzed samples showed natural fluoride; macroregions 2 and 4 showed the highest mean fluoride concentration, macroregion 4 presented the highest mean temperature, and all macroregions showed a similar pattern of precipitation. The mean fluoride concentration of the four macroregions was below the appropriate value to prevent caries. An increase in precipitation would decrease the fluoride concentration in water. In conclusion, the concentration of natural fluoride varied according to meteorological and hydrographic factors. The concentration in surface waters increased during periods of low precipitation. Therefore, this study provided important information to support implementation of community water fluoridation in this region.

Treatment of fluoride contaminated water using mango (Mangifera indica) leaves powder as an adsorbent

Excessive levels of Fluoride in water is detrimental to human health as it can cause many health problems including both dental and skeletal fluorosis etc. The aims of the current research work were to prepare a novel check the efficiency of Mango (Mangifera indica) leaves powder (MLP) for fluoride removal as well as to observe the effect of various factors over fluoride adsorption from water. The experiments were performed under batch mode and the results indicated that maximum adsorption efficiency was noticed in the acidic range. The Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) techniques were applied for adsorbent characterization. Data modeling declared that pseudo second order kinetic model and Langmuir isotherm models were in best fitting. The study concluded that the investigated adsorbent material is suitable for reducing the high fluoride concentration in water to the WHO established level and is suggested as an ecofriendly material for water purification. Conclusively, future research prospects and further modification of mango leaves materials for fluoride adsorption are recommended.

Effect of Drinking Water Fluoride on Gingivitis and Caries: A Study in Peat and Non-Peat Land: A Comparative Cross-Sectional Study.

Humans get fluoride from food and water available in their environment. The source of clean water in peatlands comes from rainwater with a low mineral content, especially fluoride. The objective of this study was to investigate the correlation between the fluoride level in drinking water and salivary fluoride levels, as well as their potential impact on dental and oral health conditions. It is a causal-comparative study with a cross-sectional approach at the Health Polytechnics of Pontianak and Yogyakarta. The population were indigenous people in peat land (Pontianak) and non-peat land (Yogyakarta). The data were pH and mineral content in drinking water, saliva, the number of Streptococcus mutans colonies, dental caries rates, and gingivitis. Drinking water fluoride is only significantly correlated with salivary fluoride on non-peat land. If these data are combined, it can be seen that drinking water fluoride is positively correlated (P < 0.05; CI 95%) with pH water, fluoride water, and pH saliva. Increased levels of fluoride in drinking water were negatively correlated with gingivitis, dental caries, and S. mutans. Drinking water fluoride is negatively correlated with dental caries and gingivitis in peatland and non-peatland communities, but would be significantly associated with dental caries and gingivitis if both peatland and non-peatland data were analyzed together. This is due to the low content of fluoride in the drinking water of peatland. Therefore, it is necessary to add fluoride gel to the teeth to prevent the development of dental caries.

Prevalence of Thyroid Disorders in and around Nalgonda District, Telangana, India: A Cross-sectional Study

Introduction: Among the endocrine disorders, thyroid disorders are the most common. Long term and excessive intake of fluoride plays a significant role in the development of thyroid disorders. Nalgonda is one of the highly drought-prone districts in Southern India and its groundwater has 10 to 15 parts per million (ppm) of fluoride in contrast to a maximum permitted level of just 1.5 ppm. The entire Nalgonda division is under the threat of fluorosis due to high concentration of fluoride in the drinking water. Aim: To assess the prevalence of thyroid disorders in and around areas of Nalgonda district, Telangana, India. Materials and Methods: A cross-sectional study was conducted in Department of Biochemistry, Government Medical College, Nalgonda, Telangana, India, from December 2021 to May 2022. Total 391 subjects attending Outpatient Department (OPD) of General Medicine, Nalgonda were included in the study. Samples were analysed for thyroid function tests (total T3,T4, thyroid stimulating hormone) by chemiluminiscence immuno assay method in an Abbott architect ci4100 automated analyser. Statistical analysis was done by using Microsoft Excel spreadsheets and results were expressed as prevalence percentages, mean±Standard Deviation (SD). Results: In the present study, the mean age was 39.5±20.506 years. Out of the total participants, 273 (69.8%) subjects were found to be euthyroid and 118 (30.2%) had thyroid disorders. Among 30.2% subjects with thyroid disorders, 32 (8.2%) were hypothyroid, 19 (4.9%) were hyperthyroid, 54 (13.8%) were having subclinical hypothyroidism, 13 (3.3%) were having subclinical hyperthyroidism. The prevalence of thyroid disorders was higher in females compared with males, with the ratio of 3:1 and females contributing to major disease burden. Conclusion: According to this study, prevalence of thyroid disorders was 30.2% with more disease burden in females. Subclinical hypothyroidism contributes to the major disease burden.

AFFECTION ON CARIES AND ITS COMPLICATIONS OF TEMPORARY TEETH OF CHILDREN IN A REGION WITH EXCESS FLUORINE CONTENT IN DRINKING WATER.

Aim: The aim of the study was to determine the indicators of caries and its complications in the temporary teeth of children who permanently live in a region with a high fluoride content in drinking water. Materials and Methods: It was examined with the definition of caries and its complications 277 children in the age range from 2 to 13 years, who were born and permanently live in the urban-type settlement of Mashivka. The fluoride content in the drinking water of the settlement was 1.7-2.5 mg/l. Results: During the analysis of data from the survey of children who were born and permanently lived in the urban-type settlement of Mashivka, it was determined that the prevalence of caries of temporary teeth probably increases with age. Half of the 3-5-year-old children had caries-affected teeth, and temporary tooth caries reached the highest rates in 10-year-old children. It should be noted that a fifth of children in the youngest age group (3-5 years old) suffer from pulpitis and periodontitis of temporary teeth. Conclusions: The conducted examination of children urban-type settlement of Mashivka confirms the opinion that the excessive content of fluorine in drinking water does not have a caries-protective effect, and the intensity of the process reaches the indicators characteristic of regions with its optimal content. Such a situation requires strengthening measures for both primary and secondary prevention of dental diseases.

Development of a tea waste-based mixture for the removal of fluoride in water: A case study with selected concentrations of fluoride in water

Development of a tea waste-based mixture for the removal of fluoride in water: A case study with selected concentrations of fluoride in water

Mapping the evidence for monitoring fluoride exposure in community prevention programmes for oral health using nail clippings and spot urine samples: a scoping review.

There is an increased interest in identifying practical and accurate biomarkers for fluoride exposure. Due to the narrow 'dose-gap' between the benefit of caries reduction and the risk of dental fluorosis, monitoring of fluoride exposure is vital when introducing any fluoridation programme for the prevention of dental caries. This scoping review aimed to ascertain the nature and extent of the available evidence on how spot urine and nail clippings are used to measure fluoride intake/exposure, by using a unique approach of mapping the studies according to population, setting, type of study design, methodology and analytical approach in community prevention programmes. Multiple relevant databases were searched up to July 2021 for any study designs, including randomised controlled studies, quasi-experimental studies, surveys, retrospective and prospective cohort studies, case studies, phenomenological studies, and expert opinions. The search retrieved 9,222 studies of which 155 met the inclusion criteria. A high proportion of the studies (25.2%) originated from Latin America and the Caribbean continent subregion. However, per country, China recorded the highest number, followed by India and Mexico. The majority (62.6%) employed a cross-sectional study design, and 65.8% combined participants from different age groups. Of the included studies, 82.6% used spot urine samples as a biomarker for assessing fluoride intake/exposure. Water fluoride concentration was reported in 66.5% of the studies with 46.6% of all included studies reporting a water fluoride concentration of > 1.2mg/L. The methods used in assessing oral hygiene and dietary intake were not reported in 72.3% and 71.0% of the included studies, respectively. Only 35.5% of the included studies assessed the relationship between fluoride exposure and excretion. This review revealed a large variability in the way in which spot urine samples and/or nail clippings are used to measure fluoride exposure in different settings and situations. Particularly, there are inconsistencies in the methodologies and the analytical approaches used in assessing fluoride exposure. Therefore, there is a need for more rigorous primary research studies using standardised approaches to determine the suitability of spot urine samples and nail clipping as biomarkers for monitoring fluoride exposure.

Fluoride exposure and blood cell markers of inflammation in children and adolescents in the United States: NHANES, 2013–2016

BackgroundIngestion of fluoride in drinking water has been shown to result in increased cellular markers of inflammation in rodent models. However, the approximately 5–10 × increase in water fluoride concentrations required in rat and mouse models to obtain plasma fluoride concentrations similar to those found in humans has made relevant comparisons of animal to human studies difficult to assess. As an increased white blood cell count (WBC) is a marker of inflammation in humans, we used available NHANES survey data to assess the associations between plasma fluoride levels in the U.S. and blood cell counts children and adolescents. MethodsMultiple linear regressions were done to determine the association of blood cell counts and plasma fluoride in publicly available NHANES survey data from the 2013–2014 and 2015–2016 cycles. Plasma fluoride concentration measurements were available only for children aged 6 to 19, inclusive, and therefore this subpopulation was used for all analyses. Covariate predictors along with plasma fluoride were age, ethnicity, gender, and Body Mass Index (BMI). ResultsPlasma fluoride was significantly positively associated with water fluoride, total WBC count, segmented neutrophils, and monocytes, and negatively associated with red blood cell count when adjusted for age, gender and BMI.ConclusionOur finding that neutrophils and monocytes are associated with higher plasma fluoride in U.S. children and adolescents is consistent with animal data showing fluoride related effects of increased inflammation. These findings suggest the importance of further studies to assess potential mechanisms that are involved in absorption and filtration of ingested fluoride, particularly in tissues and organs such as the small intestine, liver and kidney.

Assessment of Fluoride Content in Water and Its Impact on the Intelligence Quotient of School Children Aged 12–13 Years

The preliminary study was undertaken with the aim to assess the effect of fluoride content in water on the Intelligence Quotient (IQ) of school children aged 12-13 years residing in areas that differ with respect to fluoride levels. The IQ was measured using Raven's Colored Progressive Matrices in 90 children, who were life-long residents in three villages (30 children each) of similar population size but differing in the level of fluoride in drinking water. Urinary fluoride concentration was measured using the selective ion electrode technique. One-way ANOVA was used for the statistical analysis of the data. Results: Children who lived in locations with fluoride levels of 1.60, 6.70, or 2.80 parts per million in their drinking water had urinary fluoride concentrations of 1.60, 6.82, or 2.69 parts per million, and IQ scores of 16.77 + 8.24, 19.36 + 9.98, or 21.87 + 7.47, respectively. The results indicated that there was a positive correlation between excess fluoride in drinking water and IQ.

Increasing The Efficiency of Bone Charcoal in Water Defluoridation Using Eggshell Powder and Dry Banana Peel Medium (DBPM)

The world health organization (WHO) has set an upper limit of 1.5 mg/l fluoride concentration in water meant for human consumption. Ground water has high fluoride level which exceeds the value recommended by the WHO. Defluoridation is the only viable way of dealing with the issue of high fluoride levels in water. The most common defluoridation method is the use of bone charcoal. This research shows how adding dry banana peel medium (DBPM) and egg shell powder to bone charcoal increases its defluoridation capacity as well as the water defluoridation rate. Raw water samples were collected from different boreholes and their initial fluoride concentration measured. The groundwater was then subjected to different adsorbent combinations of bone charcoal, eggshell powder and DBPM and the rate of fluoride removal as well as the final concentration of fluoride in the water after two hours, were determined. Eggshell powder and DBPM were found to increase the fluoride removal capacity of bone charcoal by more than 20%. The highest fluoride removal was achieved when bone charcoal was combined compositely with eggshell powder and DBPM. Hence the addition of eggshell powder and DBPM was found to increase the defluoridation rate as well as the fluoride removal capacity of bone charcoal.

Fluoride exposure via public drinking water supplies and associated health outcomes: an ecological study in England

BACKGROUND AND AIM The protective effect of drinking water fluoridation on dental caries is established. While adverse effects are known for fluoride concentrations above 1.5mg/L, the evidence is less clear for effects at lower concentrations. In new updated analyses, we aimed to estimate the association between fluoride exposure and dental health outcomes and hip fractures. METHODS Exposure was defined as mean public drinking water fluoride concentrations, assigned to geographical areas, over time periods of interest. Concentrations were categorised: &amp;#x3c;0.1, 0.1-&amp;#x3c;0.2, 0.2-&amp;#x3c;0.4, 0.4-&amp;#x3c;0.7, &amp;#x2265;0.7mg/L. Area-level health outcomes, deprivation scores, and age- and sex-specific denominators were obtained from hospital data, oral health surveys, and routine data sources. Binomial models with logit link were used to determine the association (adjusted odds ratios) between fluoride and dental caries prevalence. Negative binomial models were used to determine the association (adjusted incidence rate ratios) with dental extractions and hip fractures. RESULTS The association between fluoride and dental outcomes varied by deprivation. Odds of caries decreased in each fluoride concentration category relative to the lowest, with the greatest reduction in the most deprived quintile (ORs 0.61-0.80, composite p&amp;#x3c;0.001). Incidence of hospital admissions for carious tooth extractions decreased similarly (IRRs 0.37-0.66, composite p&amp;#x3c;0.001). The association with hip fracture varied by age (p&amp;#x3c;0.001), with evidence of a protective association in those aged under 50 (IRRs 0.83-0.97, composite p&amp;#x3c;0.001) and an adverse association in those aged over 80 (IRRs 0.98-1.08, composite p&amp;#x3c;0.01) at some individual concentration categories. There was no evidence of a dose response. CONCLUSION Exposure to fluoride in drinking water, at concentrations &amp;#x3c;1.5mg/L, was associated with reduced dental caries and extractions. The most deprived populations benefited the most. There was no clear evidence of an association with hip fractures. The findings support adoption of water fluoridation as an equitable dental public health intervention. KEYWORDS Fluoride; oral health; fractures

Multimodal Single-Entity Electrochemical Fluoride Sensor for Fuel Cell Membrane Degradation Diagnostics

To the best of our knowledge, very few works have been done for the continuous real-time monitoring of Proton Exchange Membrane Fuel Cells (PEMFCs) membrane degradation based on fluoride-specific electrochemical microsensors. PEMFCs are eco-smart energy sources for efficient transportation but experience variable degradation rates that wear the Membrane Electrode Assembly (MEA), a critical component of the fuel cell’s functionality. Current market options lack specific diagnostics and a legitimate indication of when exactly the membrane needs to be replaced. As such, this work focused on manufacturing a sensor for measuring MEA degradation in real-time by selectively monitoring fluoride concentration in effluent water, a signature PEMFCs degradation status, through functionalized LaF3:(Au nanoparticle) thin films (∼60 nm). The sensor’s exceptional specificity/sensitivity has been achieved in real-time at a sub 10 ppb level, optimized through spin-coating deposition and post-annealing process. Its multimodal readout has been achieved and studied through the characterizations of open circuit potential, cyclic voltammetry, chronoamperometry, and differential pulse voltammetry revealing a consistent linear decrease of 15.7 mA cm−2 at 0 ppb to 10.2 mA cm−2, while also maintaining its low-cost, small size, and robustness.

Enhanced defluoridation in household filter using binary metal hydrochar composite

Elevated fluoride concentration in water can trigger several health-related problems. In this study, the influence of post pyrolysis hydrothermal activation on defluoridation has been investigated to check their interacting effect using response surface methodology. Amongst the various optimizing factors which were investigated, temperature and time emerged as the most significant factors (p-value < 0.05). The Fe–Zn (2:1) binary metal hydrochar composite synthesized from optimized hydrochar demonstrated an optimum dose, contact time, initial concentration and solution pH of 0.8 g/L, 120 min, 5 mg/L and 7 respectively. The isotherm and kinetic results indicated that experimental data best fitted to Langmuir and pseudo-second order, with a determination coefficient approaching one (R2 = 0.99). Maximum monolayer adsorption capacity for this composite was found to be 28.41 mg/g. Thermodynamic parameters corroborate that defluoridation was chemisorption in nature (ΔH⁰ >10 kJ/mol) and was favoured at lower temperature (30 °C). An extensive characterization was employed to explain the adsorption mechanism, and confirmed occurrence of Lewis acid-base interactions, ion-exchange processes and electrostatic interactions. The performance of a fixed bed column was assessed based on breakthrough curve analysis. This novel composite could therefore serve as an efficient fluoride adsorbent because of enhanced sorption at neutral pH and reusability, thereby ensuring a sustainable and practical solution for low-cost defluoridation of drinking water.

Drinking Bottled and Tap Water for Healthier Living in Volcanic Areas: Are All Waters the Same?

In most volcanic areas, the population considers the use of bottled waters as a healthier and safer option. This study aimed to (i) assess the fluoride concentrations in tap and bottled water consumed on São Miguel Island, (ii) confirm the accuracy of the labeling of fluoride levels on bottled water, and (iii) assess the fluoride daily intake and risk exposure and discuss the possible health effects in adults and children. Fluoride concentrations were measured in tap water (49 samples) and bottled water (23 samples) with a fluoride ion-selective electrode. The fluoride concentration was above the recommended limit in tap water from Sete Cidades (1.71 mg/L), in bottled waters nº 5 and 7 from category C (2.05 ± 0.04 mg/L and 2.36 ± 0.14 mg/L, respectively), and in bottled water nº 5 from category D (1.92 ± 0.03 mg/L). Fluoride daily intake in children reached a maximum value in gasified water nº 7 (0.059 mg F/day/kg). The risk assessment evidenced that all the brands with over 1.2 mgF/L might be a concern for potential non-cancer health effects, especially in adults. The most recognized brands of gasified and gasified flavored waters represent a higher risk of exceeding fluoride daily intake when compared to tap and mineral bottled waters.

Nanogravimetric Monitoring of Electrochemically Driven Fluoride Ion Extraction from Water By Aniline-Based Copolymer Films

Sustainable access to safe drinking water is a global societal goal [1]. Accordingly, much attention has been given to the development of technologies for remediation of the unintended effects of agricultural practices and industrial processes. The case of fluoride in water is an interesting case in two respects: its desirability up to a point and its natural origins. The beneficial effects of fluoride on dental health are recognized: in some countries drinking water is routinely fluoridated. However, high levels of fluoride can have detrimental effects on teeth, bones and internal organs; the recommended upper limit is 1.5 mg/L. The fluoride concentration in natural waters - the source of most drinking water - is dictated by the presence of calcium ions, through the solubility product of calcium fluoride. Dependent on the local geology, the calcium ion concentration may be relatively low or high, such that either the beneficial effects of fluoride may not be realized or its injurious effects may dominate. Determination of fluoride concentration using ion selective electrodes is well-established. The question then is how to remedy high fluoride levels. Existing methods for removal of excess fluoride from drinking water and wastewater include precipitation (as Ca or Al salts), membrane technologies and adsorption. Each of these has limitations, e.g. high costs, toxic by-products and slow or complex processes.Here we explore electrochemically controlled fluoride ion extraction by electroactive polymer films. This approach has been studied for water softening (using polypyrrole [2]) and perchlorate removal (using polypyrrole composites [3] and polyaniline-based copolymers [4]). Here we explore the feasibility of using a range of polyaniline-based materials in an electrochemically switched ion exchange system for fluoride removal from water [5]. The concept is based on F- ion uptake as counter ions in the oxidation (p-doping) of the conducting polymer film. Upon oxidation, the film will “capture” F- ions from solution. After separation of the purified water, the F- ions would then be ejected into a concentrated waste stream by reduction (un-doping) of the oxidized polymer.In this presentation we compare the characteristics and performance of polyaniline, poly(o-aminophenol) and poly(o-toluidine) homopolymer films with each other and with those of their copolymers of various composition. Film deposition is controlled electrochemically and monitored nanogravimetrically using the EQCM. Acoustic impedance enables distinction between gravimetric and viscoelastic interpretation of the response [8]. The extent of redox-driven fluoride uptake is then determined upon exposure to solutions of varying fluoride (and in some cases chloride) concentration. Correlation of EQCM-derived film mass and charge responses is used to assay fluoride and solvent uptake during film oxidation and reduction. Comparison with the total redox site population (from the response in fluoride-free media) yields the efficiency. Observations for these aniline-based homopolymers and copolymers reveal behavior that is quite different to that seen for typical small anionic dopants, such as chloride, nitrate and perchlorate. Further, there are surprisingly diverse responses to fluoride for these relatively similar polymeric materials, notably the extent of film solvation change during fluoride uptake. Use of different electrochemical control functions and timescales reveals differences in fluoride ion uptake and release rates. The relevance of these data to defluoridation will be discussed.

Preliminary Protein Profiling of Sodium Fluoride treated Lactobacillus acidophilus and Lactobacillus salivarius

Sodium fluoride is a trace element required for human beings to prevent early dental disorders and to meet body’s minimum Fluoride levels. It is signified as a nutritional supplement for the prevention of dental caries in children of areas with inadequate Fluoride concentration in the drinking water. When Fluoride concentration exceeds required levels in the body, it commences bacteriostatic activity against beneficial flora in the gastrointestinal tract. Two such commonly affected organisms are L. acidophilus and L. salivarius. These are probiotic organisms that help to maintain immunogenic gut against several pathogenic organisms. In our previous study, Minimum inhibitory concentration (MIC) and growth dynamics were assessed on L. acidophilus and L. salivarius, in the presence of different Sodium fluoride concentrations. L. acidophilus and L. salivarius were observed to be inhibited at 20 mM and 40 mM Sodium fluoride concentrations respectively. These inhibitory concentrations were selected for further analysis. The proteins were isolated from such Sodium fluoride treated and untreated cells, the protein concentration was estimated by Bradford assay and protein profiling was done by 1D Gel Electrophoresis. The protein concentration is found to be higher in Sodium fluoride untreated organisms and below 3 kDa proteins of Sodium fluoride treated samples. Whereas low protein concentration was observed in the above 3 kDa protein samples (L.acidophilus treated protein sample above 3 kDa and L.salivarius treated protein sample above 3 kDa) of fluoride treated organisms. L. acidophilus and L. salivarius showed difference in protein expression under fluoride stress. Protein expression is high in L. salivarius than L. acidophilus. This is an indication that these strains have different capabilities for adapting to varying environmental conditions. we conclude that there is no impact on below 3 kDa protein samples in Sodium fluoride treated organisms and impact was there on the above 3 Kda proteins which are inhibited.