Fluoride Concentration In Water Research Articles

Dye-assisted analysis of fluoride in water using UV–visible spectrophotometry: a preliminary study

Abstract Dye-assisted method for the analysis of fluoride content of water has been developed in this study using dyes obtained from some flowering plants. This was done to evaluate the potentials of locally accessible dyes in spectrophotometrically detecting F– levels in fluoride-containing water samples. Dye solutions obtained from scarlet jungle flame, Hibiscus flower, Peacock flower or Barbados pride, Royal poinciana, Pink bauhinia, Barbados lily, or Easter lily were adopted to monitor absorbance and corresponding concentrations of serially prepared F− concentrations in a range of 0.001–0.012 ppm. Dye from the Hibiscus flower gave an optimal performance with R2 = 0.9792. Using this dye, the F– content in water samples obtained from tap waters from Moremi Estate, Modomo, Asherifa, Postgraduate Hall of Obafemi Awolowo University, Ile-Ife, and a well water sample from Modomo gave 0.052, 0.053, 0.053, 0.058, and 0.061 ppm, respectively. A comparison of these values indicated that all the water samples monitored were safe for human consumption without experiencing health challenges as the maximum F– limit for potable water recommended by WHO was not exceeded. This study concluded that dye from Hibiscus flower could satisfactorily assist in monitoring F– content in water where ion-selective electrodes are not readily accessible.

Assessing impacts of cemeteries on water quality in an urban headwater watershed with mixed human‐built infrastructure

AbstractCemeteries are understudied integral components to urban watersheds, which provide ecosystem services but can also export nutrients, trace elements, and other contaminants to nearby water bodies. In this study, we focus on Meadowbrook Creek, an urban headwater stream in Syracuse, New York (USA), which has shown significant nitrate contributions from a local cemetery. We collected biweekly surface water samples over the course of 1 year from 2022 to 2023 for analysis of major and trace elemental concentrations including Na, Ca, Mg, K, F, Cl, sulfate, and nitrate. Here, we aim to assess the impact of various human infrastructures on urban stream water quality with a particular focus on the cemetery and nitrate. A comparison between the new dataset in this study and previously reported water chemistry data in Meadowbrook in 2012 suggests a decade‐long impact of road salting and the cemetery on water quality particularly with respect to Na, Cl, and nitrate. Sulfate, Mg, Ca, and K are likely mainly geogenic. Stable nitrogen isotope data, the usage of concrete or steel vaults in the cemetery in the past 50 years, and the lack of correlation between nitrate and fluoride concentrations in stream water argue against burial decay products being a major source of nitrate to the stream. Instead, other nitrate sources that exist in the cemetery such as, fertilizer, decaying plant material, and wastewater, are more viable dominant nitrate sources. In addition, nitrate loading calculations indicate that the groundwater‐connected reach, including the cemetery, acts as an annual net sink for nitrate despite the seasonally varying sink‐source patterns.

Determination of Fluoride Content of Selected Brands of Bottled Water Sold in Lafia Town using Two Different Methods

Fluoride is a well known compound for preventing dental caries, and its major root of ingestion is potable water. In this research, fluoride concentration in five brands of bottled-water samples sold in Lafia city (A, B, C, D and E) was investigated. Five different batches of each brand were analyzed. Samples were determined via potentiometric, and photometric methods. The mean concentration of fluoride within the investigated samples, were of the range 0.30 – 0.44 mg/L which were below WHO recommended limit, except sample B (0.53 mg/L) which was within the recommended limit. In the photometric method, the concentrations of the samples were within the range of 0.51 – 0.88 mg/L which were within WHO recommended limit. The outcome of this research suggests that within areas where there is elevated content of fluoride in water, bottled-water should be consumed instead of tap water because the former minimizes the danger of fluorosis. However, people who majorly drink bottled-water maybe at higher risk of dental caries; and need to take fluoride supplements. In this study, concentration of fluoride determined by photometric method was significantly higher than that of ISE method (P<0.05). Hence, photometric method was more sensitive than the ISE method.

Fluoride exposure and thyroid hormone levels in pregnancy: The MIREC cohort

BackgroundFluoride exposure may increase the risk of hypothyroidism, but results from previous studies are inconsistent at low-level fluoride exposure (i.e., ≤0.7 mg/L). Human studies of fluoride and thyroid hormone levels in pregnancy are scarce. ObjectivesWe examined associations between fluoride exposure and maternal thyroid hormone levels in a Canadian pregnancy cohort, with consideration for fetal sex-specific effects. MethodsWe measured fluoride concentrations in drinking water and spot urine samples collected during each trimester from 1876 pregnant women enrolled in the Maternal-Infant Research on Environmental Chemicals (MIREC) study. We also measured maternal thyroid stimulating hormone (TSH), free thyroxine (FT4), and total thyroxine (TT4) levels during the first trimester of pregnancy. We used linear and non-linear regression models to estimate associations between fluoride exposure and levels of TSH, FT4, and TT4. We explored effect modification by fetal sex and considered maternal iodine status as a potential confounder. ResultsA 1 mg/L increase in urinary fluoride was associated with a 0.30 (95 %CI: 0.08, 0.51) logarithmic unit (i.e., 35.0 %) increase in TSH among women pregnant with females, but not males (B = 0.02; 95 %CI: −0.16, 0.19). Relative to women with urinary fluoride concentrations in the first quartile (0.05–0.32 mg/L), those with levels in the third quartile (0.49–0.75 mg/L) had higher FT4 and TT4 (i.e., inverted J-shaped associations), but the association was not statistically significant after adjustment for covariates (p = 0.06). Water fluoride concentration showed a U-shaped association with maternal FT4, whereby women with water fluoride concentrations in the second (0.13–0.52 mg/L) and third (0.52–0.62 mg/L) quartiles had significantly lower FT4 compared to those with levels in the first quartile (0.04–0.13 mg/L). Adjustment for maternal iodine status did not change the results. DiscussionFluoride exposure was associated with alterations in maternal thyroid hormone levels, the magnitude of which appeared to vary by fetal sex. Given the importance of maternal thyroid hormones for fetal neurodevelopment, replication of findings is warranted.

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.

Dental and alveolar pathologies of the Early Iron Age population of the Upper Ob region based on the materials of the Bystrovka-3 burial ground)

The study is focused on the analysis of distribution of the dentoalveolar pathologies (caries, calculus, periodontitis, dental fluorosis, antemortem enamel chips, alveolar abscess, antemortem loss of teeth), which are generally used for revealing the diet component composition of ancient groups and as the markers of the stress episodes (enamel hypoplasia, child dental caries). In addition, several anomalies in the structure of the dentition (dystopia, crowding, hypo- and hyperdentia) are considered. The study is based on the anthropological materials of the Bolsherechenskaya culture of the Bystrovka-3 burial ground, dated to the second half of the 1st millennium BC. The series consist of 130 skulls: 46 male, 34 female, 26 infants and 24 individuals whose gender could not be determined. The frequencies of the pathologies of the Bystrovka-3 sample were compared with those of the Neolithic and Bronze Ages populations of Western Siberia. The results of the study reveals that diet of the Bystrovka-3 people included both animal and plant products. The presence of endemic fluorosis on the teeth of four people (two female and two infants) may indicate the migration of a small group of people from outer regions with high fluoride content in soil and water to the Bolsherechye area. It was also found that the representatives of the study group experienced significant stress caused by adverse environment event. In addition, in the main group several rather rare dentoalveolar anomalies were identified, which, according to some researchers, are hereditary. Comparative analysis of frequencies of dentoalveolar pathology of the study group and the Neolithic-Bronze Age population of the south of Western Siberia revealed that the component composition of the diet of Bolsherechye people had significant differences from that of the Bronze Age pastoralists and is more similar to the Neolithic and pre-Andronovo bronze populations of Baraba forest-steppe, which had similar economy structure based on fishing, gathering and hunting.

Prenatal fluoride exposure, offspring visual acuity and autonomic nervous system function in 6-month-old infants

BackgroundPrenatal fluoride exposure can have adverse effects on children’s development; however, associations with visual and cardiac autonomic nervous system functioning are unknown. We examined associations between prenatal fluoride exposure and visual acuity and heart rate variability (HRV) in 6-month-old infants. MethodsWe used data from Canadian mother-infant pairs participating in the Maternal-Infant Research on Environmental Chemicals (MIREC) cohort. We estimated prenatal fluoride exposure using: i) fluoride concentration in drinking water (mg/L), ii) maternal urinary fluoride adjusted for specific gravity (MUFSG; mg/L) and averaged across pregnancy, and iii) maternal fluoride intake (µg/kg/day) from consumption of water, tea, and coffee, adjusted for maternal body weight (kg). We used multivariable linear regression to examine associations between each measure of fluoride exposure and Teller Acuity Card visual acuity scores (n = 435) and assessed HRV (n = 400) using two measures: root mean square of successive differences (RMSSD) and the standard deviation of N-N intervals (SDNN) measured at 6-months of age. ResultsMedian (IQR) values for water fluoride, MUFSG, and daily fluoride intake were 0.20 (IQR: 0.13–0.56) mg/L; 0.44 (0.28–0.70) mg/L and 4.82 (2.58–10.83) µg/kg/day, respectively. After adjustment for confounding variables, water fluoride concentration was associated with poorer infant visual acuity (B = -1.51; 95 % CI: −2.14,-0.88) and HRV as indicated by lower RMSSD (B = -1.60; 95 % CI: −2.74,-0.46) but not SDNN. Maternal fluoride intake was also associated with poorer visual acuity (B = -0.82; 95 % CI: −1.35,-0.29) and lower RMSSD (B = -1.22; 95 % CI: −2.15,-0.30). No significant associations were observed between MUFSG and visual acuity or HRV. ConclusionFluoride in drinking water was associated with reduced visual acuity and alterations in cardiac autonomic function in infancy, adding to the growing body of evidence suggesting fluoride's developmental neurotoxicity.

Determinants of oral health status: an ecological study in Iran

ObjectivesThe aim of this ecological study was to assess the association between behavioral, social position, circumstance factors, and caries experience in 35- to 44-year-old adults in Iran at a provincial level.Materials and methodsThe data from the 2011 Iranian Oral Health Survey were obtained from all 31 provinces across Iran on the population level. Oral health status was measured as the number of decayed, missing (MT), and filled (FT) teeth and the percentage of the population who were edentulous. Data were also gathered from each province on the percentage of smokers (Non-Communicable Diseases Risk Factors Surveillance Provincial Report 2009), per capita consumption of free sugars, concentration of fluoride in the drinking water (National and Sub-national Burden of Disease (NASBOD) Survey), number of dentists per 10,000 people, mean years of schooling of adults, expected years of schooling of children, life expectancy at birth and Gross National Income (Integrated Public Use Microdata Series, Global Data Lab). The data were analyzed using simple and multiple linear regression (α = 0.05).ResultsMean DMFT was positively associated with the percentage of smokers (B = 0.01 95%CI 0.01–0.14), and negatively with fluoride concentration (B =-2.6 95%CI -4.3- -0.96). The edentulousness percentage was positively associated with smoking (B = 0.2 (with 95%CI: 0.07–0.37) and negatively with mean years of education (B =-1.08 (with 95%CI: -2.04- -0.12). DT was associated with expected years of schooling (B =-0.6 (with 95%CI: -1.07- -0.17), negatively. Mt was negatively associated with life expectancy (B =-0.5 (with 95%CI: -1.1- -0.007), fluoride concentration (B =-3.4 (with 95%CI: -4.5- -1.5) and number of dentists per 10,000 people (B =-0.4 (with 95%CI: -0.8- -0.01). Mean Years of Schooling (B = 0.5 (with 95%CI: 0.2–0.8) and number of dentists per 10,000 people (B =-0.62 (with 95%CI: 0.51 − 0.48) were positively in associated with FT.ConclusionsThe present findings indicate that there were differences in the oral health measures and their social determinants among the provinces of Iran. Regarding the limitations of the study especially the limitation of the number of independent variables, it seems, this discrepancy could be better explained by social variables of the provinces such as income than by environmental factors.

3 Fluoride Exposure and Hypothyroidism in Pregnant Women: A Potential Mechanism of Fluoride Neurotoxicity

Objective:Fluoride exposure has been associated with thyroid dysfunction, but fluoride's impact on thyroid function in pregnancy is unclear, especially during early gestation when the fetus is dependent on maternal thyroid hormone. We examined the potential thyroid-disrupting effects of maternal fluoride exposure in pregnancy and tested whether thyroid disruption in pregnancy mediates the association between maternal fluoride exposure and child intelligence quotient (IQ) among Canadian mother-child dyads living in areas with optimal fluoridation.Participants and Methods:We measured fluoride concentrations in drinking water and in spot urine samples collected in each trimester from pregnant women enrolled in the Maternal-Infant Research on Environmental Chemicals study. We also measured thyroid hormone (thyroid stimulating hormone [TSH], free thyroxine [FT4], and total thyroxine [TT4]) levels during the first trimester of pregnancy and categorized women as euthyroid (n=1301), subclinical hypothyroid (n=100), or primary hypothyroid (n=28). Those categorized as primary hypothyroid were combined with an additional 79 women who reported clinical diagnoses at time of study enrolment (total n=107). In a sample of 1508 women, we used logistic regression to estimate the association between fluoride exposure and risk of either subclinical or primary hypothyroidism, separately, and linear regression to estimate associations between fluoride exposure and women's thyroid hormone levels (TSH, FT4, TT4). We tested effect modification by child sex and thyroid peroxidase (TPO) antibody status. In a subsample of 439 mother-child pairs, we measured child Full-Scale IQ (FSIQ) at 3-4 years of age using the Wechsler Preschool and Primary Scale of Intelligence. We used linear regression to test associations between maternal hypothyroidism or thyroid hormone levels, and children's FSIQ scores. Finally, mediation analysis in the counterfactual framework was used to estimate the proportion of the effect of maternal fluoride exposure on child FSIQ mediated by maternal hypothyroidism, through evaluation of the natural direct (not through hypothyroidism) and indirect (through hypothyroidism) effects.Results:Using categorical measures of thyroid status, a 0.5 mg/L increase in water fluoride concentration was associated with a 1.64 (95% confidence interval [CI], 1.04 to 2.58) increased odds of primary hypothyroidism. This association was stronger among women with normal TPO antibody levels (< 5.61 IU/mL) (odds ratio, 2.80; 95% CI, 1.24 to 6.36). In contrast, we did not find a significant association between maternal urinary fluoride and hypothyroidism. For continuous measures of thyroid hormone levels, a 1 mg/L increase in maternal urinary fluoride was associated with a 35% (p=0.01) increase in TSH among women pregnant with a female fetus. In our subsample analyses, children born to women with primary hypothyroidism had lower FSIQ than children of euthyroid women, especially among boys (B, 8.78; 95% CI, -16.78 to -0.79). In contrast, maternal TSH, FT4, and TT4 levels were not significantly associated with child FSIQ scores. Maternal primary hypothyroidism did not significantly mediate the relationship between maternal water fluoride concentration and child FSIQ (p natural indirect effect= .35).Conclusions:Fluoride in drinking water may increase the risk of hypothyroidism in pregnancy. Thyroid dysfunction in pregnancy may be one mechanism underlying developmental neurotoxicity of fluoride.

Control of Fluoride Pollution in Cemented Phosphogypsum Backfill by Citric Acid Pretreatment.

Using phosphogypsum (PG) as the aggregate of cemented backfill is an economical and effective method of PG utilization. However, the stability and performance of cemented backfill are challenged by the rich fluoride content in PG. In this study, the effects of citric acid pretreatment on PG defluorination, backfill performance and environmental behavior were investigated by washing PG with different concentrations of citric acid and washing times. The results showed that the citric acid pretreatment could significantly reduce the fluoride content in PG and promote the hydration reaction with the binder, thus greatly reducing the usage and cost of the binder in actual production. Considering the efficiency of defluorination, the optimal citric acid concentration and washing times were determined to be 4% and 7-8 times, respectively. In addition, after citric acid pretreatment, the viscosity and setting time of the backfill slurry and the porosity of the backfill reduced, and the strength of the backfill improved, which was conducive to slurry pipeline transportation and underground mine stability. Finally, a further analysis of environmental behavior was conducted and it was found that the citric acid washing greatly reduced the content of fluoride in the bleeding water of slurry and the backfill leachate, which met the integrated wastewater discharge standard in China. The results of this study can provide important guidance for the large-scale recycling and environmental management of PG.

Probable impact of environmental radiation on thyroid swellings in areas of Eastern Hyderabad and Nalgonda

IntroductionThyroid swellings are prevalent in 4 to 7% of the Indian population and are commonly present in females. Thyroid swelling has been attributed to various causes, such as ingestion of goitrogens and low iodine in the diet in benign, radiation exposure, and genetic in malignancies. Eastern Hyderabad and Nalgonda have a high fluoride content in the ground water, which can potentially disrupt thyroid functioning. Moreover, the region also harbors high uranium content and environmental radiation; hence, a retrospective analysis of the FNAC and histopathology of the thyroid swellings was done to evaluate the paradigm.MethodA retrospective analysis of the patient’s records from February 1, 2022, to January 31, 2023, was conducted considering all the patients who presented with thyroid swelling. The variables taken into consideration were age, gender, and FNAC findings. A correlation was also made with the histopathology of the specimen of operated patients.ResultA total of 88 medical records of the patients were evaluated, and it was determined that there was a preponderance of females with a ratio of 8.77:1. Majority of the swellings were Benign labeled as Bethesda category 2 (n = 61) followed by category 3 (n = 11). To be considered are the cases of malignancies falling into category 6, which comprise 7.95% (n = 7). The majority of the patients were seen between the ages of 31 to 40 (n = 28), followed by 41 to 50 (n = 25).On comparing with the histopathological reports, two cases of category 5 were found to be having papillary thyroid carcinoma and another with follicular thyroid carcinoma making the number of proven malignancies to be 10.22% (n = 9). Other histopathological findings correlated with the results of FNAC.ConclusionThrough this pilot study, we conclude that most thyroid swellings were benign, but there is a higher incidence of thyroid malignancies (10.22%), significantly higher than the country average of 2 to 4%. The higher number of malignant cases can be attributed to many factors, including high fluoride content and environmental radiation. Further studies need to be conducted, taking each element individually.

Association between drinking water fluoride and the serum alkaline phosphatase and phosphate levels in pregnant women and newborn infants.

Endemic fluorosis (skeletal and dental) is a serious public health problem in many parts of the world, especially in India. Age, sex, dietary calcium (Ca), the hormonal status, the dose and duration of the fluoride intake, and renal efficiency in handling fluoride all influence fluoride metabolism. The aim of the study was to evaluate the effect of the fluoride present in drinking water on the serum alkaline phosphatase (ALP) and phosphate levels in pregnant women and newborn infants. In the present cross-sectional study, the participants were categorized into 2 groups based on a fluoride concentration in their drinking water: the low/optimum-fluoride group (<1 ppm); and the high-fluoride group (≥1 ppm). Each group was comprised of 90 pregnant women who were recruited from the hospital at the time of admission for delivery. Fluoride was measured in their drinking water, urine, maternal serum, and cord blood. The ALP and phosphate levels were measured in serum using a fully automated analyzer. The drinking water consumed by the pregnant women contained fluoride, which was significantly positively correlated with the urine and blood serum fluoride levels. There were significant differences in the ALP levels between the 2 groups in both maternal serum and cord blood. The level of phosphate in maternal serum was significantly higher in the high-fluoride group. The results of both simple and multivariate regression analyses revealed that the fluoride content in drinking water was significantly associated with the ALP level in cord blood and the phosphate level in maternal serum. The ALP levels were negatively associated with drinking water fluoride concentrations in both maternal serum and cord blood. The phosphate levels in maternal serum were positively associated with drinking water fluoride concentrations.

Fluoride contamination in ground-drinking water and urine from rural population of Uttar Pradesh, India

This study was carried out to assess the fluoride concentration in ground-drinking water, vegetable juice and urine samples of the five villages in Lakhimpur (Kheri) of Uttar Pradesh, India. The experimental site retains a few agro-based industries like sugarcane processing units due to it enriched cultivation by the local farmers. Hence, the availability of fluoride in ground-drinking water is natural, and its excess intake through drinking water over a period caused irreversible serious illness affecting the nervous system and osteo-dental fluorosis. The fluoride level in ground-drinking water found from 0.5 to 4.3 mg L−1 with average of 3.42 mg L−1. Total number of residents involved in the study for analyzing their urine samples were 548 (277 males and 271 females). The absorption of fluoride was high among the youngsters (13–44 yrs). The positive correlation observed between fluoride content in ground drinking water intake and urine.

A comparative analysis of water quality guidelines for fluoride in Canada and Spain

Although anthropogenic fluoride (F−) pollution is a serious worldwide environmental problem, only a few countries have currently established national water quality criteria for the protection of freshwater biota. Since Canada is a global leader in biodiversity conservation that exhibits restrictive water quality benchmarks, I carry out a comparative analysis of water quality guidelines for fluoride in Canada and Spain. The Canadian water quality benchmark of 0.12 mg F−/l (maximum allowable concentration) prevents Canada’s fresh waters from significant adverse events of fluoride pollution, thereby protecting sensitive native aquatic invertebrates and adult-migrating Pacific salmon. By contrast, the Spanish water quality benchmark of 1.7 mg F−/l (annual mean concentration) allows not only continuous levels of fluoride pollution more than six times higher than natural fluoride concentrations in the fresh waters of mainland Spain, but also much higher discontinuous levels of fluoride pollution (&gt; 15 mg F−/l). This unacceptable scenario is contrary to the current environmental goal of “zero pollution” in the European Union. In view of the existing toxicological data, a Spanish water quality guideline of 0.15−0.3 mg F−/l (maximum allowable concentration) seems much more reasonable. The recommended water quality guideline for fluoride would much better protect sensitive native fish and invertebrate species, and prevent significant bioaccumulation of fluoride in tolerant freshwater organisms.

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.

A National Study Exploring the Association Between Fluoride Levels and Dental Fluorosis

While the effects of fluoride on health have been widely researched, fewer high-quality studies examine the association of fluoride levels in water and dental fluorosis. To investigate the association between fluoride exposure from drinking water and dental fluorosis. This cross-sectional study used the 2013-2014 and 2015-2016 National Health and Nutrition Examination Survey (NHANES) data (January 1, 2013, through December 31, 2016). NHANES uses a complex sampling technique to develop nationally representative sample estimates of the US population that consists of interviews and physical assessments. Children and adolescents aged 6 to 15 years were included because NHANES contains their data for all 3 forms of fluoride measures: plasma fluoride levels, water levels of fluoride, and dietary fluoride supplementation. Data were analyzed from January 1 to April 30, 2023. Water and plasma fluoride levels were measured by laboratory personnel. Dietary fluoride supplement data were self-reported. The Dean's Fluorosis Index was used to evaluate fluorosis status for each tooth. The dental fluorosis severity value was based on the second most affected tooth. Independent variables included plasma and water fluoride concentrations and dietary fluoride supplementation. An independent samples t test was used to compare fluoride exposures between groups, and Pearson correlation assessed the association between plasma and water fluoride levels. To assess whether fluoride exposures were associated with dental fluorosis, logistic regression analyses were conducted. There were 1543 participants in the 2013-2014 NHANES cycle (weighted proportion male, 51.9%; mean [SD] age, 11.0 [2.7] years) and 1452 in the 2015-2016 cycle (weighted proportion male, 52.6%; mean [SD] age, 11.1 [2.8] years). A weighted 87.3% exhibited some degree of fluorosis in the 2013-2014 cycle and 68.2% in the 2015-2016 cycle. Higher fluoride levels in water and plasma were significantly associated with higher odds of dental fluorosis (adjusted odds ratios, 2.378 [95% CI, 2.372-2.383] in the 2013-2014 cycle and 1.568 [95% CI, 1.564-1.571] in the 2015-2016 cycle). The findings of this cross-sectional study suggest that exposure to higher concentrations of fluoride in water and having higher plasma levels of fluoride were associated with a greater risk of dental fluorosis. Further research can help policy makers develop policies that balance substantial caries prevention with the risk of dental fluorosis.

Relationships between dental fluorosis and fluoride concentrations in bottled water and groundwater in low-income children in Mexico.

The aim of the current study was to investigate associations between dental fluorosis in children living in low socioeconomic areas in Mexico, and fluoride concentrations in tap water, fluoride concentrations and in bottled water, and body mass index (BMI). A cross-sectional study involving 585 schoolchildren aged 8-12 years was conducted in communities in a southern state of Mexico with >0.7 parts per million (ppm) fluoride in the groundwater. The Thylstrup and Fejerskov index (TFI) was used to evaluate dental fluorosis, and the World Health Organization growth standards were used to calculate age-adjusted and sex-adjusted BMI Z-scores. A BMI Z-score ≤ -1 SD was used as the cut-off point for thinness, and multiple logistic regression models for dental fluorosis (TFI ≥ 4) were constructed. The mean fluoride concentration in tap water was 1.39 ppm (SD 0.66), and the mean fluoride concentration in bottled water was 0.32 ppm (SD 0.23). Eighty-four children (14.39%) had a BMI Z-score ≤ -1 SD. More than half (56.1%) of the children presented with dental fluorosis in TFI categories ≥ 4. Children living in areas with higher fluoride concentrations in the tap water [odds ratio (OR) 1.57, p = 0.002] and bottled water (OR 3.03, p < .001) were more likely to have dental fluorosis in the severe categories (TFI ≥ 4). BMI Z-score was associated with the probability of dental fluorosis (TFI ≥ 4; OR 2.11, p < 0.001), and the effect size was 29.3%. A low BMI Z-score was associated with a higher prevalence of dental fluorosis in the severe category. Awareness of the fluoride concentrations in bottled water may help prevent dental fluorosis, particularly in children exposed to several high fluoride content sources. Children with a low BMI may be more vulnerable to dental fluorosis.

A low-cost, colorimeter-based portable device, for rapid, on-spot determination of fluoride in water

ABSTRACT Accurate fluoride measurement in water is required for selecting safe water sources or for treatment options to lessen its impact on public health. A low-cost, portable device has been developed as a rapid fluoride measurement system. It works with an optimal concentration of alizarin red S-zirconium complex (ARS-Zr, the sensor reagent). The device is an LED-phototransistor-based assembly to detect changes in light absorbance at 527 nm, due to monotonically decreasing ARS-Zr concentration with increasing fluoride concentration in water. We have optimised reagent composition in the device, enabling us with a wider fluoride detection range (0.2–9 ppm), rapidly within 4 min; simultaneously ensuring better reagent stability for up to 34 days. Limit of detection (LOD) and limit of quantification (LOQ) of the device are 0.2 and 0.6 ppm, respectively. The device replicates an analytical spectrophotometer’s performance, with a maximum error up to 5% in only a couple of cases. The hand-held device does not give any interference in the presence of even a very high 200 ppm concentration of other common heavy metals (, ,, ,) and anions (, , , , CH3COO−, ), which can be present in water. Fluoride concentration measurement above 1 ppm is unaffected, by even high phosphate concentration up to 10 ppm (typical phosphate level being only ≤ 2.3 ppm). Similarly, for silica concentration up to 10 ppm (typical silica level being 1-30 ppm), fluoride measurement remains unaffected. However, the presence of gives significant interference with fluoride. Overall, we demonstrate the device as an on-spot method, for rapid fluoride measurement, independent of TDS (57.6–151 ppm), pH (6.6–12.5) or conductivity (111.2–283 µS/cm) of the samples, at a low device cost of US$ 25 and reagent cost of 0.44 cents per sample.

Abnormal fluoride distribution, human health risk assessment, predicted no-effect concentration (PNEC) and environmental hazards in an Egyptian lake connected to the Mediterranean Sea

Fluoride can affect the metabolism and physiological functioning of humans and aquatic organisms like any hazardous substance when it exceeds its permissible limits and PNEC values. The fluoride content of the lake water and sediment samples collected from different locations was determined to assess its risks to humans and its ecological toxicity in Lake Burullus. Statistical analyses show that the proximity of the supplying drains had an impact on the fluoride content. Fluoride ingestion and skin contact in lake water and sediment during swimming for child, female and male were evaluated at 95, 90, and 50%. The values of hazard quotient (HQ) and total hazard quotient (THQ) for children, females and males were less than one, reflecting that exposure to fluoride through ingestion and skin-to-skin contact while swimming poses no risks to human health. PNEC values for fluoride in lake water and sediment were estimated using the equilibrium partitioning method (EPM). The ecological risk assessment of fluoride for acute and chronic toxicity was performed for the three trophic levels based on the PNEC, the half-maximal effective concentration (EC50), the median lethal dose (LC50), the no-observed effect concentration (NOEC), and the 5% lethal concentration (EC05). The risk quotient (RQ), mixture risk characterization ratios (RCRmix), relative contribution (RC), toxic unit (TU), and sum of toxic units (STU) were estimated. The acute and chronic RCRmix(STU) and RCRmix(MEC/PNEC) produced similar values for the three trophic levels in lake water and sediment, indicating that invertebrates are the most sensitive species to fluoride. These results of evaluating the environmental risks of fluoride in lake water and sediments reflected its significant impact on aquatic organisms living in the lake area in the long term.

E031 A rare case of diffuse osteosclerosis

Abstract Background/Aims Diffuse skeletal fluorosis is a common condition in countries with high content of fluoride in the ground water like India and China. Skeletal fluorosis in the UK is rare and presents with non-specific findings such as back pain, elevated ALP or bone sclerosis. We describe a case referred from haematology for investigation of osteosclerosis. Methods 74-year-old female presented to the emergency department on several occasions with recurrent abdominal pain, severe low back pain and swelling of her lower limbs. Her mobility had been reduced due to previous femoral nerve injury. Blood tests on admission showed mild macrocytic anaemia. Alkaline phosphatase, renal, liver function tests and electrolytes were within normal range. Furthermore, calcium, phosphate, vitamin D and parathyroid hormone levels were within normal limits. CT CAP was done and no obvious or sinister cause for abdominal pain was found. However, it showed diffuse bony sclerosis. Bone densitometry DXA scan results as follows: T-score of + 1.6 in the hip and +1.7 in the neck of femur, they were unable to scan the lumbar spine as the patient was unable to tolerate positioning for the scan. This confirmed relatively raised bone density for patient’s age despite having risk factors for osteoporosis like previous wrist fracture, strong family history of osteoporosis, early menopause following total hysterectomy at age 41, coeliac disease and multiple falls due to poor mobility. Results A bone marrow aspirate and trephine biopsy and immunophenotyping were carried out and did not demonstrate any evidence of myeloid or lymphoid neoplasm. The next line of investigations included an isotope bone scan and blood tests including serum tryptase, uric acid and fluoride levels. Fluoride level came back as 411 which is 8-times more than the normal value. Patient mentioned that she uses fluoride toothpaste and brushed her teeth at least 10-14 times/day. X-ray of the hands showed no evidence of periosteal reactions or sclerosis. We recommended that she use fluoride free toothpaste and referred her for a dental opinion. While there is no effective therapeutic agent to reduce fluoride levels, patient was encouraged to use fluoride free toothpaste and also consult with her dentist for further evaluation. Conclusion This case emphasises the need for a comprehensive history and maintaining a high index of suspicion of skeletal fluorosis when encountered with a patient with a high bone mineral density (BMD) score on the DXA scan or diffuse skeletal sclerosis. The increase in bone mineral density is thought to be related to fluoride’s enhanced osteoblastic activity. Disclosure S. Mohamed: None. A. Phillips: None. J. Thomas: None. D. Makkuni: None.