Average Fluoride Concentration Research Articles

Analysis of the distribution across media, migration, and related driving factors of fluoride in cold and arid lakes during the freezing period

Fluoride pollution in water has become a global challenge. This challenge especially affects China as a country experiencing serious fluoride pollution. While the have been past studies on the spatial distribution of fluoride, there has been less attention on different forms of fluoride. This study collected 176 samples (60, 40, and 76 ice, water, and sediment samples, respectively) from Lake Ulansuhai during the freezing period. The occurrence and spatial distribution characteristics of fluoride in lake ice-water-sediment were explored using Kriging interpolation, Piper three-line diagram, and Gibbs diagram analysis methods. The migration and transformation of fluoride during the freezing period were revealed and the factors influencing fluoride concentration in the water body were discussed considering the hydrochemical characteristics of lake surface water. The results showed that the average fluoride concentrations in the upper ice, middle ice and lower ice were 0.18, 0.09, and 0.12 mg/L, respectively, decreasing from north to south in the lake. The average concentrations of fluoride in surface water and bottom water were 0.63 and 0.83 mg/L, respectively. The concentrations of fluoride in ice and water were within the World Health Organisation drinking water threshold of 1.50 mg/L and the Class III Chinese surface water standard (GB3838-2002). The average sediment total fluorine was 1344.38 ± 200 mg/kg, significantly exceeding the global average (321 mg/kg) and decreasing with depth. The contents of water soluble, exchangeable, Fe/Mn bound, organic bound, and residual fluorides were 40.22–47.18, 13.24–43.23, 49.52–160.48, and 71.59–173.03 mg/kg, respectively. There was a significant positive correlation between fluoride concentration in ice and that in water. The change in fluoride concentration in water was mainly due to specific climatic and geographical conditions, pH, hydrochemical characteristics and ice sealing. This study is of great significance for the management of high-fluorine lakes in arid and semi-arid areas.

Variability of groundwater fluoride and its proportionate risk quantification via Monte Carlo simulation in rural and urban areas of Agra district, India

This study quantifies the groundwater fluoride contamination and assesses associated health risks in fluoride-prone areas of the city of Taj Mahal, Agra, India. The United States Environmental Protection Agency (USEPA) risk model and Monte Carlo Simulations were employed for the assessment. Result revealed that, among various rural and urban areas Pachgain Kheda exhibited the highest average fluoride concentration (5.20 mg/L), while Bagda showed the lowest (0.33 mg/L). Similarly, K.K. Nagar recorded 4.38 mg/L, and Dayalbagh had 1.35 mg/L. Both urban and rural areas exceeded the WHO-recommended limit of 1.5 mg/L, signifying significant public health implications. Health risk assessment indicated a notably elevated probability of non-carcinogenic risk from oral groundwater fluoride exposure in the rural Baroli Ahir block. Risk simulations highlighted that children faced the highest health risks, followed by teenagers and adults. Further, Monte Carlo simulation addressed uncertainties, emphasizing escalated risks for for children and teenagers. The Hazard Quotient (HQ) values for the 5th and 95th percentile in rural areas ranged from was 0.28–5.58 for children, 0.15–2.58 for teenager, and 0.05–0.58 for adults. In urban areas, from the range was 0.53 to 5.26 for children, 0.27 to 2.41 for teenagers, and 0.1 to 0.53 for adults. Physiological and exposure variations rendered children and teenagers more susceptible. According to the mathematical model, calculations for the non-cancerous risk of drinking water (HQ-ing), the most significant parameters in all the targeted groups of rural areas were concentration (CW) and Ingestion rate (IR). These findings hold relevance for policymakers and regulatory boards in understanding the actual impact and setting pre-remediation goals.

Regional and racial/ethnic inequalities in public drinking water fluoride concentrations across the US

BackgroundAlthough the US Centers for Disease Control and Prevention (CDC) considers fluoridation of community water systems (CWSs) to be a major public health achievement responsible for reducing dental disease, recent epidemiologic evidence suggests that chronic exposure to population-relevant levels of fluoride may also be associated with adverse child neurodevelopmental outcomes. To our knowledge, a nationally representative database of CWS fluoride concentration estimates that can be readily linked to US epidemiologic cohorts for further study is not publicly available. Our objectives were to evaluate broad regional and sociodemographic inequalities in CWS fluoride concentrations across the US, and to determine if county-level racial/ethnic composition was associated with county-level CWS fluoride.MethodsWe generated CWS-level (N = 32,495) and population weighted county-level (N = 2152) fluoride concentration estimates using over 250,000 routine compliance monitoring records collected from the US Environmental Protection Agency’s (EPA) Third Six Year Review (2006–2011). We compared CWS-level fluoride distributions across subgroups including region, population size served, and county sociodemographic characteristics. In county-level spatial error models, we also evaluated geometric mean ratios (GMRs) of CWS fluoride per 10% higher proportion of residents belonging to a given racial/ethnic subgroup.Results4.5% of CWSs (serving >2.9 million residents) reported mean 2006–2011 fluoride concentrations ≥1500 µg/L (the World Health Organization’s guideline for drinking water quality). Arithmetic mean, 90th, and 95th percentile contaminant concentrations were greatest in CWSs reliant on groundwater, located in the Southwest and Eastern Midwest, and serving Semi-Urban, Hispanic communities. In fully adjusted spatial error models, the GMR (95% CI) of CWS fluoride per a 10% higher proportion of county residents that were Hispanic/Latino was 1.16 (1.10, 1.23).Impact statementWe find that over 2.9 million US residents are served by public water systems with average fluoride concentrations exceeding the World Health Organization’s guidance limit. We also find significant inequalities in community water system fluoride concentration estimates (2006–2011) across the US, especially for Hispanic/Latino communities who also experience elevated arsenic and uranium in regulated public drinking water systems. Our fluoride estimates can be leveraged in future epidemiologic studies to assess the potential association between chronic fluoride exposure and related adverse outcomes.

Fluoride Concentration in Baby Milk Formulas Available in Riyadh Pharmacies, Saudi Arabia

Purpose: This study aimed to ascertain the fluoride concentrations in infant formula (baby milk) sold in pharmacies situated in Riyadh, Saudi Arabia, and to confirm the accuracy of the fluoride quantities declared on the package. Methods: 26 different infant formulae product samples from 13 manufacturers were obtained from pharmacies in Riyadh, Saudi Arabia. Two different products from the same manufacturer measured fluoride concentrations (one product for the 0-6 months age group and one for the 1-3 years age group) using a combination fluoride-ion-selective electrode. Results: The average concentration of fluoride for all the samples measured was 0.987 µg/g. In all but one sample, there was a wide difference between the declared Fluoride concentrations and what was measured. The difference was smallest in Humana Bebemil 1 which had 0.84 µg/g (measured) and 0.75 µg/g (declared). The average intake of fluoride is way below the recommended daily allowance. The quantities of fluoride that can potentially be consumed, depending on the brand, ranged from 0.115 mg/day to 0.206 mg/day. Conclusion: All the analyzed infant formulae did not reveal fluoride concentrations above the recommended daily allowance. One can cautiously assume that there is no risk for children to suffer from over-exposure to fluoride.

Flúor em Moçambique: estudo retrospectivo

ABSTRACT Objective: The study aims to analyse the fluoride concentration in the water supply of the capital of each province of Mozambique, 2019 and compare with previous data 1978 and 2008. Methods: The water supply in cities of Mozambique were analysed in 1978, 2008 and 2019 and water from Tete’s River in 1978 and 2019. The fluoride concentration of the water samples was determined in duplicate, using the ion-sensitive electrode (Orion 9609), coupled to a potentiometer (Procyon, model 720), adopting a significance level of 5%. Results: The average fluoride concentration found in the years 1978, 2008 and 2019 was 0.31, 0.33 and 0.14 mg F/L, respectively. The fluoride concentrations collected from household taps in 1978, 2008 and 2019 were: Cabo Delgado/Pemba (0.62, 0.28 and 0.07 mg F/L), Niassa/Lichinga (0.18, 0.98 and 0.07 mg F/L), Nampula/Nampula (0.18, 0.01 and 0.06 mg F/L), Zambézia/Quelimane (0.81, 0.37 and 0.15 mg F/L), Tete/Tete (1.00, 0.97 and 0 .46 mg F/L), Sofala/Beira (0.00, 0.01 and 0.10mg F/L), Manica/Chimoio (0.04, 0.01 and 0.07 mg F/L), Inhambane/Inhambane (0.00, 0.05 and 0.19 mg F/L), Gaza/Xai-Xai (0.01, 0.06 and 0.06 mg F/L) and Maputo (0.23, 0.36 and 0.23 mg F/L), respectively. In the waters of the Zambeze River was 5.5 mg F/L in 1978 and 0.12 mg F/L in 2019. There was no significant change between the fluoride concentrations in the water collected from the taps during the periods studied (p=0.83), however there was a significant difference in the water collected from the river (p<0.05). Conclusion: Tete’ River showed a significant reduction in fluoride concentration, and in the piped water collected in all municipalities, the fluoride content was below optimum.

Fluoride and silver ion concentrations and pH in silver diamine fluoride solutions from Argentina.

The aim of this study was to measure the fluoride (F) and silver (Ag) ion concentration and the pH, over time, of 2 solutions of 38% silver diamine fluoride (SDF) produced in Argentina. The brand Fluorsilver® was established as Group 1 (G1) (Densell), and the brand FAgamin® (Tedequim) as Group 2 (G2), each with two different lots. The following were determined at time 0 (t0) and 30 days after opening (t30): a) fluoride concentration (w/v) by visible spectrophotometry b) Ag content (w/v) by atomic absorption spectrophotometry c) pH. Results: The data in the freshly opened bottles were for G1 lot1/lot2: a) 0.96/1, b) 8.3/7.8, c).11.5/11.3; G2 lot1/lot2: a) 11.5/9.9, b) 39/39, c) 7/6,9; and after 30 days, G1 lot1/lot2: a) 0.85/0.81, b) 7.2/8.2, c) 11.3/11.6; G2 lot1/lot2: a) 9.35/8.43, b) 38/38, c) 7.6/7.6. Conclusion In relation to the expected values (5.0-5.9% fluoride and 24.4-28.8% silver), the average concentration of fluoride and silver ions was lower for G1, but higher for G2. The pH was alkaline for G1 and neutral for G2. Over the 30 days, the content of fluoride and silver tended to decrease.

Comprehensive assessment of water quality and associated health risks in an arid region in south Iran

This study aims at investigating the quality of drinking water and evaluating the non-carcinogenic risk of fluoride and nitrate ions in drinking water, and fluoride in tea in Zarrin Dasht, Iran. We focus on tea since it is the most popular drink among Iranian people and in the study region. We collected and analyzed 23 drinking water samples and 23 tea samples from different locations in the study region. Based on the water quality index, the consumed drinking water does not have a good quality in most Zarrin Dasht areas. Accordingly, the water quality index (WQI) is poor and very poor in 70% and 13% of the water samples, respectively. The average fluoride concentration of the tea samples is 2.71 mg/L. The mean values of Fluoride Hazard Index (HIfluoride) are 3.77, 2.77, and 2.33 for children, teenagers, and adults, respectively, which are higher than the safe limit of 1. The Nitrate Hazard Index (HInitrate) is higher than the safe limit of 1 in 8.7% of the samples. The results of the Monte Carlo simulation demonstrate that HIfluoride and HInitrate are higher than 1 in all the groups, except for adults. According to the results of the sensitivity analysis, ingestion rate and body weight have a large effect on HIfluoride and HInitrate, but body weight is inversely associated with sensitivity. According to the Piper diagram, saline water is the predominant type in Zarrin Dasht. Besides, the results of the principal component analysis (PCA) show a high correlation between fluoride and pH, which could be related to the effect of pH on fluoride dissolution and ion exchange. Therefore, appropriate measures are recommended to be taken in order to reduce the amount of fluoride in the drinking water resources of this region. Reduction of tea consumption can also be considered an important factor in decreasing the amount of fluoride intake.

Risk Assessment for fluoride ion in Groundwater in Kurnool District of Andhra Pradesh

Generally, the fluoride ion in drinking water helps to human by preventing tooth decay. But excess fluoride in Drinking water will lead to Dental, and Skeletal fluorosis. Recent studies proved that excess provide in drinking water will produces different organ failures. So risk assessment study was carried in the study area. Total 10 samples collected from the hand pumps in rural village in Kurnool district, Andhra Pradesh state. The collected samples are analyzed for physical parameters and fluoride. The obtained results are compared with BIS standards. The average fluoride concentration observed 0.68 ppm and it is within the prescribed samples specified by BIS. Risk assessment carried out by using hazard quotient. After the investigation, confirmed that no risk observed for the collected samples. Keywords: Fluoride, Dental fluorosis, Skeletal Fluorosis, Physical parameters, Hazard quotient.

Study on the diffusion of hydrogen fluoride in an electrolytic fluoride plant based on CFD numerical simulation method

Objective: Using CFD technology to grasp the distribution and diffusion of hydrogen fluoride in an electrolytic fluorine plant, provide guidance and scientific basis for enterprises to carry out occupational health management in enterprises, install hazardous substance alarm devices, and protect workers' occupational health. Methods: In July 2019, the diffusion law of hydrogen fluoride gas produced in an electrolytic fluorine plant is selected as the research object. Through the establishment of models and grids, the Fluent numerical simulation method is finally used to simulate the diffusion and distribution of hydrogen fluoride gas under ventilation conditions. Results: The results showed that the average concentration of hydrogen fluoride was 0.045 mg/m(3) in the workplace, and the absorbed zone height (1.5 m) was 0.02 mg/m(3) in the inspection channel, which was in accordance with the national standard. However, there is eddy current above the electrolyzer near the inlet, may lead to the accumulation of hydrogen fluoride gas. Conclusion: The research of CFD numerical simulation method on the distribution and diffusion of hydrogen fluoride concentration in electrolytic fluorine plant can be applied to the prevention, control and management of occupational hazards in electrolytic fluorine plant.

Fluoride Contamination in Groundwater and Its Effect on Human Health: Case Study of Baramati Tehsil Area, India

Baramati Tehsil is the rural part of the Pune district which have an arid to semi-arid region. Groundwater is the main source of drinking water for the people living in this area. The groundwater is being removed from a dug well and borewells in the study area for drinking purposes. The present study studied, fluoride from Dug well water of the Baramati Tehsil area. A total of 15 groundwater samples of dug well were collected in post-monsoon (POM) winter 2015 to pre-monsoon (PRM) summer 2017 for four seasons by using standard methods of American Public Health Association (APHA). The various physico-chemical parameters such as pH, Electrical conductivity (EC), Total Dissolved Solids (TDS), Total Hardness (TH), Calcium (Ca2+), Magnesium (Mg2+), Sodium (Na+), Potassium (K+), Bicarbonate (HCO3-), Chloride (Cl-), Sulphate (SO42-) and Fluoride (F-) were determined using standard procedures of APHA suggested for determination of the water quality for drinking purpose. The results obtained from the analysis was used for interpretation of fluoride and other ions concentration and the effect on human health. Results obtained indicate that the fluoride concentrations in POM and PRM were within the maximum permissible limit of WHO and BIS recommended for drinking. World Health Organization (WHO 2006) has fixed a safe limit of fluoride from 0.5 to 1.5 mg/l in drinking water. The maximum fluoride concentration in the study area was 0.68 mg/l while the minimum was 0.12 mg/l and the average fluoride concentration was 0.41 mg/l in all four seasons. The drinking water intake with fluoride content less than 0.5 mg/l can cause tooth decay. The groundwater of all wells was suitable for drinking purposes without treatment for fluoride removal at the time of analysis.

Hazardous exposure of children with heavy metal in a southwestern city of Iran

ABSTRACT This study aimed to investigate the concentration and risk of carcinogenic and non-carcinogenic causes due to skin and drinking exposure with water in 27 points of potable water in Shiraz. The total samples were 162 the studied variables included fluoride and heavy metals (HMs). The results showed that the concentration of all parameters in winter was higher than in summer (p value < 0.05). However, the concentration in this study was lower than the standards of Iran, the World Health Organization (WHO), and the United state environmental protection agency (USEPA). The average fluoride (F−) concentration in summer and winter was 462 and 588 µg/L, respectively. The lead concentration in winter (8.91 µg/L) was higher than in summer (5.86 µg/L). So, in 40% of the samples, it was higher than the WHO standard. Zinc (Zn) and cadmium (Cd) concentrations were lower than allowed, and only 70% and 15% of winter samples were above the WHO standard. The chronic daily intake (CDI) for variable was F− > Zn > Cu > Pb > Cr > As > Cd but HQ < 1 for all HMs. The risk of cancer and non-cancer caused by HMs in children due to dermal and drinking exposure has been higher than in other groups. Chromium (Cr) cancer risk (1.84 × 10−4) in children has been 30 times higher than the allowable limit. The highest risk of non-carcinogenic risk was caused by arsenic in the children group. Overall, the best chemical quality of water was in the centre to the west of the city. So that most of the parameters were in optimal condition. However, cancer and non-cancer risk through drinking have been significant, especially in children.

Dental Fluorosis in Children from Aguascalientes, Mexico: A Persistent Public Health Problem

This paper estimates the prevalence and severity of dental fluorosis among participants in the first wave of The Aguascalientes Longitudinal Study of Child Development (EDNA). The analytical sample includes 1052 children in 100 public elementary schools. Dental fluorosis is determined using the Modified Dean’s Index. There is a 43% general dental fluorosis prevalence, and the estimated Community Fluorosis Index is 0.99. Five municipalities report average groundwater fluoride concentrations above the official Mexican guideline value of 1.5 mg/L. In those municipalities, there is a 50% average dental fluorosis prevalence. An ordered logistic regression analysis indicates that obesity in participants increases the likelihood of suffering more severe dental fluorosis symptoms compared with normal-weight participants (OR = 1.62, p &lt; 0.05). Households consuming tap water are more likely to have children suffering more severe dental fluorosis symptoms (OR = 1.63, p &lt; 0.05). Children aged 8 years are more likely to present more severe dental fluorosis symptoms than their peers aged 7 years (OR = 1.37, p &lt; 0.05). Dental fluorosis will persist as a public health problem in Aguascalientes State unless appropriate technologies for fluoride removal from water are installed and operated.

Spatial distribution and potential health risk of fluoride in drinking groundwater sources of Huaibei, Anhui Province

Fluoride enrichment in drinking groundwater at Huaibei leads to potential health risk to the residents. A total of 49 groundwater samples from groundwater sources were collected to evaluate the potential health risk of fluoride ingestion through drinking water for children and adults in Huaibei. Results shown that the average concentration of fluoride in centralized sources is less than that of decentralized sources, which may be attributed to different geological conditions including fluoride-rich minerals, environmental conditions and high fluoride waste discharge. The corresponding health risk value of fluoride in centralized source is lower than that in decentralized one, and the HI values of fluoride in the three exposed groups varied in the same order: infants > children > adults. Infants and children were more sensitive receptors to the non-carcinogenic health hazards of fluoride than adults. Special care should be taken to infants and children for the highly prone to health risk compared to adults.

FLUORIDE CONCENTRATION AND OTHER ELEMENTS IN TOOTH STRUCTURE AND ITS EFFECT ON DENTAL CARIES IN KIRKUK, IRAQ

The study involved the determination of fluoride and other elements like Mn, Na, Mg, Si, K, Ca, Fe, Al, Cl and some trace elements (Cr, Cd, Ni, Zn, Pb, Sr, As, Co, Cu, Mo and Se) in 220 teeth samples with age group ranging from 6–45 year. The average concentration of fluoride in samples were less than the global average, and the total contents of fluoride in the children deciduous teeth are relatively higher than that of permanent teeth. The infection rate of dental caries in children seen in age between 6–11 years and increasing after the age of 12 due to certain environmental factors, age, water and food quality, so there is a strong relationship between the rising amount of fluoride concentration in the area and reducing the rate of dental caries. The study also determines the different limits and importantly the optimum value of fluoride concentration in drinking water of Kirkuk City which is done by correlation with the mean value of the maximum daily temperature of the city over the last five years, and also taking in consideration that human gets the fluoride from a different source such as food, air and tooth paste, so we correlate our finding with the rate of fluoride taken from other sources which not greater than 6mg/day, according to World Health Organization (WHO), in order to avoid the hyper fluorosis (excess fluoride).

Study on the Emission Characteristics of PCDD/Fs and Other Multiple Pollutants in Flue Gas from Sintering Plant in China

In China, sintering flue gas has become the most important source of air pollution rather than burning coal-fired flue gas.The emission characteristics and removal efficiencies of various gaseous pollutants were studiedon a 180 m2 sintering equipped with a semi-dry oxidative desulfurization and denitrification system in Tangshang, Hebei province. The emission concentrations of particulate matter, fluoride,NOX and SO2were measured in the flue gas whilepolychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs) were tested in both flue gas and dust ash at 100% and 60% loadconditions. The collections and analyses ofpollutantswere used by smoke sampler, TESTO350 and dioxin sampleraccording to national standards of China. The results shown that the average emission concentration of particulate matter, fluoride, NOX and SO2 in the inlet of the flue gas purification system were 47.4 mg/m3, 0.12 mg/m3, 150 mg/m3 and 521 mg/m3 while the emission concentrations in the outlet were 1.2 mg/m3, 0.07 mg/m3, 24 mg/m3 and 20 mg/m3,respectively. Through the flue gas purification system, the PCDD/Fs concentrations were reduced from 23.12 ng/m3to 1.14 ng/m3at100% load and from 12.25 ng/m3 to 0.84 ng/m3at60% load. The PCDD/Fs concentrations in the dust ash were about 178.56~197.21 ng/kg. Thedesulfurization and denitrification system significant reduced effect on the emission of particulate matter, fluoride, NOX, SO2 and PCDD/Fs with the value 97.5%, 41.7%, 84.0%, 96.2% and 95.1% at 100% load, respectively.The removal affects increases along the chlorination degree of PCDD/Fs. Meanwhile,the different load influenced the emission concentrations and removal rates of PCDD/Fs in the flue gas, the removal effects increases as the load increases. Although the desulfurization and denitrification system has good removal effects on various pollutants, the dioxins were enriched in the dust ashso as to cause secondary pollution.

Fluoride Exposure During Pregnancy and Offspring IQ

Research Article| December 01 2019 Fluoride Exposure During Pregnancy and Offspring IQ AAP Grand Rounds (2019) 42 (6): 70. https://doi.org/10.1542/gr.42-6-70 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Cite Icon Cite Search Site Citation Fluoride Exposure During Pregnancy and Offspring IQ. AAP Grand Rounds December 2019; 42 (6): 70. https://doi.org/10.1542/gr.42-6-70 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search toolbar search search input Search input auto suggest filter your search All PublicationsAll JournalsAAP Grand RoundsPediatricsHospital PediatricsPediatrics In ReviewNeoReviewsAAP NewsAll AAP Sites Search Advanced Search Topics: fluorides, offspring, prenatal exposure Source: Green R, Lanphear B, Hornung R, et al. Association between maternal fluoride exposure during pregnancy and IQ scores in offspring in Canada. JAMA Pediatr. 2019; 173(10): 940– 948; doi: https://doi.org/10.1001/jamapediatrics.2019.1729Google Scholar Investigators from multiple institutions in Canada and the United States conducted a prospective study to assess the association between prenatal fluoride exposure and IQ in children. Participants were children of women from 6 Canadian cities who were enrolled in the Maternal-Infant Research on Environmental Chemicals program during the first 14 weeks of pregnancy between 2008–2011. Prenatal exposure to fluoride was assessed using 2 measures. First, maternal urinary fluoride (MUF) concentration, adjusted for urine specific gravity, was the average fluoride concentration from 3 specimens collected during each trimester of pregnancy. The other estimate of exposure was based on self-reported consumption of tap water, tea, and coffee during the first and third trimesters; fluoride intake was then estimated based on the fluoride measurements at the water treatment plants serving the participants’ postal code. The Wechsler Preschool and Primary Scale of Intelligence (third edition) was administered to study children when they were 3–4 years old. The primary outcome was Full Scale IQ (FSIQ). Regression analyses were used to assess the association of 1 mg changes in fluoride exposures (using each measure of exposure) with this outcome. The following covariates were included in the regression models: city, maternal education level, race/ethnicity, and quality of the home environment (quantified by Home Observation for Measurement of the Environment [HOME] scores) as well as a child sex interaction term. IQ testing was completed by 601 children. Of these, MUF data were available for 512 children, and maternal fluoride intake during pregnancy information was available for 400. Mean MUF concentrations were significantly higher for women living in communities with fluoridated drinking water than in those living in communities without fluoride supplementation (0.69 mg/L and 0.40 mg/L, respectively; P<.001). The overall estimated change in FSIQ for every 1 mg/L increase in MUF concentration was −1.95 (95% CI, −5.19, 1.28). There was a significant interaction between child sex and MUF. In boys, a 1 mg/L increase in MUF was associated with a −4.49 (95% CI, −8.38, −0.60) change in FSIQ. There was no statistically significant association between MUF in FSIQ in girls. Among women with fluoride intake data, 162 (40.5%) lived in cities with fluoridated drinking water, and 238 (59.5%) drank non-fluoridated tap-water during pregnancy. A 1 mg increase in daily maternal fluoride intake during pregnancy was associated with a change in FSIQ of −3.66 (95% CI, −7.16, −0.15) in study children, with no significant interaction between intake and child sex. The authors conclude that maternal exposure to higher levels of fluoride during pregnancy was associated with lower FSIQ in their children when they were 3–4 years old. Dr Chung has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device. The AAP... You do not currently have access to this content.

Design and optimization of an electrocoagulation reactor for fluoride remediation in underground water sources for human consumption

Fluoride remediation in underground waters of volcanic origin was performed at laboratory scale using an electrocoagulation (EC) technique. The natural waters from certain volcanic springs on the island of Tenerife (Canary Islands, Spain) contain average fluoride concentrations in excess of 7 mg/L. Thus, it is necessary to treat the water for fluoride mitigation below the maximum acceptable concentration of 1.5 mg/L according to Spanish regulations for drinking water. The design and optimization of a sustainable process was accomplished using a progressive scale-up procedure involving three pilot reactors with different configurations and effective working volumes. A bipolar electrode cell design using aluminum electrodes was used in all cases. The good performance of the process was confirmed by reducing the fluoride concentration from 7.35 to 1.4 mg/L. The following optimized operating conditions were determined for a continuous flow cell system: current density, 10 mA/cm2; residence time, 10 min; and, half-period of polarity reversal, 1 min. Furthermore, the kinetics of the remediation process can be fitted using the Variable Order Kinetic (VOK) model, with a power relationship between fluoride concentration and residence time in the EC reactor.

Community level defluoridation of groundwater with limestone derived adsorbent

Fluorosis is a worldwide, chronic degenerative disease caused by excessive level of fluoride in drinking water, mostly impacting rural, resource poor communities. Success of any technological solution to this problem, by reducing fluoride in water to safe level, is contingent on its feasibility to be implemented under resource limited circumstances for extended periods. Keeping these constraints in mind, we have developed a method to adsorb fluoride using surface modified limestone, using a simple and scalable process. The adsorbent was prepared using crystalline calcium carbonate, calcium chloride and monobasic sodium phosphate as the main ingredients. Surface and elemental analyses showed that fluoride constituted up to 3.8% of the surface of the saturated adsorbent. Kinetic data showed that the diffusional resistance was a rate limiting step to water defluoridation. Pilot scale operation of the process in a rural tenement with local help to prepare the adsorbent and treat 700 l of groundwater each day for 4 months was demonstrated. During this period the average fluoride concentration of the feed water was 7.1 ppm, and was reduced to 1.0 ppm by the treatment. We also show that the saturated adsorbent could be regenerated by acid wash followed by surface modification.

FIMAR: A new Fluoride Index to mitigate geogenic contamination by Managed Aquifer Recharge

The objective of this study is to develop a Fluoride Index for mitigation of geogenic contamination by Managed Aquifer Recharge (FIMAR). This index was tested by applying to the Pambar river basin in southern India. About 40% of the study area had fluoride >1.5 mg/L, contributed from the dissolution of fluorite, fluorapatite, biotite and hornblende. The relationship between groundwater level and fluoride concentration exhibited two types of relationship. In shallow wells, groundwater recharge during monsoon increases the groundwater level and dilutes the fluoride concentration. During summer, evaporation decreases the groundwater levels and increases the fluoride content. In deep wells, the fluoride-rich salts that is deposited in the unsaturated zone due to evaporation in the pre-monsoon season is flushed during groundwater recharge and thus, the fluoride concentration increases with increase in groundwater level. This relationship was used as a key layer in FIMAR. Overlay analysis including the well type derived from the groundwater level and fluoride fluctuation, average fluoride concentration, geology, geomorphology, soil, drainage density, land use, lineament density and thickness of the weathered zone indicated 30% of the area was suitable for MAR to mitigate fluoride contamination. Since the construction of new MAR structures is cost-intensive, it is proposed to rejuvenate the existing ponds in the areas identified by FIMAR to induce recharge and dilute fluoride concentration. The positive impact was confirmed using numerical and geochemical modelling. This proves that FIMAR can be used as a planning tool in fluoride endemic areas and that the future MAR methods will be beneficial to mitigate geogenic fluoride contamination.

Study of Defluoridation of Water Using Natural Clay Minerals

AbstractFluoride is an essential component in the mineralization of bones and in the formation of dental enamel. Excessive intake may result, however, in teeth mottling and dental and skeletal fluorosis. With an average fluoride concentration of ~2.4 mg L−1 in Tunisian drinking water, the present study focused on promoting low-cost materials for removal of excess fluoride. Two Tunisian raw clays were used as adsorbents in a batch process to eliminate excess fluoride ions from drinking water and, thus, avoid fluorosis phenomena. Physicochemical characterization and chemical analysis of the raw clays were carried out using X-ray fluorescence, X-ray diffraction, and the BET method. For fluoride removal, the effects of contact time, adsorbent dose, and pH were evaluated. The optimum defluoridation capacity was at 30 min of contact time, 20 g/L of clay dose, and at pH = 3. The kaolinite tested removed more fluoride than smectite. The selected clay was used successfully to remove fluoride from contaminated water with high concentrations of foreign ions that exceeded the potability limits. Adsorption isotherms revealed that the data fitted well to both the Langmuir and Freundlich adsorption isotherms, thus confirming both monolayer and multilayer adsorption.