Plasma Fluoride Concentrations Research Articles

The Association between Fluoride and Bone Mineral Density in US Children and Adolescents: A Pilot Study.

The aim of this study was to examine the association between fluoride exposure and bone mineral density (BMD) in children and adolescents. We used data from the National Health and Nutrition Examination Survey (NHANES) 2015-2016. The fluoride concentrations in the water samples, plasma samples, and urine samples were measured electrometrically using an ion-specific electrode. Total body less head BMD (TBLH BMD) was measured using dual-energy X-ray absorptiometry (DXA). Weighted generalized linear regression models and restricted cubic splines (RCS) regression models were used to analyze the relationships between the three types of fluoride exposure and TBLH BMD. We performed subgroup analyses stratified by sex. A total of 1413 US children and adolescents were included in our study. In our linear regression models, we found inverse associations between fluoride concentrations in water and plasma and TBLH BMD. Additionally, we discovered a non-linear association between fluoride concentrations in water and plasma and TBLH BMD. No significant association or non-linear relationship was found between urine fluoride levels and TBLH BMD. This nationally representative sample study provides valuable insight into the intricate connection between fluoride exposure and skeletal health in children and adolescents.

Effect of zinc intake on association between fluoride exposure and abnormal sex steroid hormones among US pubertal males: NHANES, 2013-2016.

Excessive fluoride exposure can disturb the balance of sex hormones. Zinc is essential for sex hormone synthesis and spermatogenesis. But it is not clear how zinc affects the relationship of fluoride exposure with abnormal sex steroid hormones. Here, a total of 1008 pubertal males from the National Health and Nutrition Examination Survey (NHANES) in two cycles (2013-2014, 2015-2016) were enrolled. The concentrations of water fluoride and plasma fluoride and the levels of serum testosterone, estradiol, and sex hormone binding globulin (SHBG) were measured. Two 24-h dietary recall interviews were conducted to assess the dietary zinc intake. The relationships of fluoride exposure and zinc intake with sex hormones were examined using linear regression and logistic regression models, while the generalized additive model was used to evaluate their non-linear relationship. Our findings revealed that for every two-fold increase in plasma fluoride concentration, testosterone levels decreased by 7.27% (95% CI - 11.49%, - 2.86%) and estradiol levels decreased by 8.73% (95% CI - 13.61%, - 3.57%). There was also significant non-linear association observed between zinc intake and SHBG levels. Being in the first tertile of plasma fluoride had a 60% lower risk of high SHBG (OR = 0.40, 95% CI 0.18, 0.89) compared with being in the second tertile. When compared to the first tertile, being in the second tertile of zinc intake was associated with a 63% (OR = 0.37, 95% CI 0.14, 0.98) lower risk of high SHBG. Furthermore, we observed an interactive effect between the plasma fluoride and zinc intake on estradiol and SHBG, as well as the risk of high SHBG (P-interaction < 0.10). These findings suggest that fluoride exposure and zinc intake can affect sex steroid hormone levels and the risk of high SHBG. Notably, zinc intake may alleviate the increased risk of high SHBG and the abnormal changes of estradiol and SHBG caused by higher fluoride exposure.

Dose-response relationship between toothpaste soluble fluoride absorbed in the gastrointestinal tract and saliva fluoride secretion

Aim: This study aimed to evaluate if there is a dose-response relationship between toothpaste chemically soluble fluoride absorbed in the gastrointestinal tract and fluoride secreted by saliva, giving support to the use of saliva as surrogate for plasma fluoride. Methods: A 4-phase single blind study was conducted, in which 10 participants were subjected in each phase to one of the assigned treatment groups: group I: fresh sample of a Na2FPO3/CaCO3-based toothpaste with 1,334 μg F/g of total soluble fluoride (TSF) and groups II–IV: aged samples of this toothpaste presenting TSF concentrations of 1,128, 808, and 687 μg F/g, respectively. In all phases, the participants ingested an amount of toothpaste equivalent to 70.0 μg F/Kg body weight, as total fluoride (TF). Saliva and blood samples were collected before (baseline) and up to 180 min after toothpaste ingestion as indicator of fluoride bioavailability. F concentration in saliva and blood plasma was determined with a fluoride ion-specific electrode. The areas under the curve (AUC) of F concentration versus time (AUC = ng F/mL × min) and the peaks of fluoride concentration (Cmax) in saliva and plasma were calculated. Results: A significant correlation between mg of TSF ingested and the AUC (r=0.47; p&lt;0.01), and Cmax (r=0.59; p&lt;0.01) in saliva was found; for TF, the correlation was not significant (p&gt;0.05). In addition, the correlations between plasma and saliva fluoride concentrations were statistically significant for AUC (r=0.55; p&lt;0.01) as for Cmax (r=0.68; p&lt;0.01). Conclusion: The findings support that saliva can be used as a systemic biomarker of bioavailable fluoride present in Na2FPO3/ CaCO3-based toothpaste.

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.

Fluoride toxicity: A tale of two sources

The aim of this study was to identify the cause and source of two patients’ clinical manifestations. Case#1 was a 47-year-old male with diffuse bone pain and weakness aggravated by exertion. Past medical history revealed two surgeries for a left fibular fracture with eventual resection of installed hardware. Current medications included: oxycodone, montelukast, and vitamin D3. Magnetic resonance imaging and x-ray showed L5–6 fusion and diffuse trabecular thickening. A pelvic bone biopsy showed features consistent with severe skeletal fluorosis. Case#2 was a 61-year-old male post-heart transplant patient. His medications included: cyclosporine A, prednisone, rosuvastatin, amlodipine, and voriconazole. He complained of joint pain, his alkaline phosphatase was 222 U/L (reference range 40–129 U/L), and his bone density scan showed periostitis. Fluoride was measured in heparinized-plasma in both patients using a fluoride ion-selective-electrode on an Orion™ Dual Star pH/ISE meter (Thermo Scientific). The analytical measurement range is 4.0–21.0 μmol/L with an upper reporting limit of 105 μmol/L. Case#1 and case#2 had plasma fluoride concentrations of 11.3 and 17.5 μmol/L, respectively (reference-range < 4 μmol/L). Fluoride is often added to drinking water, toothpastes, and mouth rinses to prevent dental cavities. While food generally contains low levels of fluoride, tea and seafood have been found to have higher levels. Several medications containing fluorine are used for treating skin diseases and cancer. Following ingestion, plasma concentrations peak within an hour and up to 50% is stored in bones/teeth while the rest is primarily eliminated in the urine. The average person ingests ∼2–3 mg fluoride per day with a recommended daily intake of 3–4 mg/day by the United States Department of Agriculture. Chronic ingestion exceeding 20 mg/day can pose a risk to bone health leading to denser brittle bones, joint pain, and limited joint movement. In case#1, the source of fluoride was identified as excessive consumption of strong black tea (> 10 servings per day). In case#2, voriconazole (trifluorinated antifungal) was associated with the development of excess fluoride and periostitis. Plasma fluoride testing can be useful for diagnosing acute environmental toxicity, as well as, monitoring those taking fluorine-containing drugs. Detailed patient histories are required to identify common (voriconazole) or less-common (tea) sources. Patient#1 limited his tea consumption to one cup/day and his fluoride levels returned to normal on follow-up three months later. Patient#2 was switched from voriconazole to itraconazole (nonfluorinated triazole) and fluoride levels returned to normal. Pain resolution or improvement was also noted in both cases.

Fluoride Status and Cardiometabolic Health: Findings from a Representative Survey among Children and Adolescents.

There is preliminary evidence to suggest a positive association between fluoride exposure and higher blood pressure among children, but population-based biomarker studies are lacking. Thus, data from the 2013/2014 and 2015/2016 cycles of the US-based National Health and Nutrition Examination Survey (NHANES) were analysed to evaluate the association between plasma fluoride concentrations and blood pressure among children and adolescents aged 8 to 19 years. Secondary analyses were carried out on fluoride status in relation to further markers of cardio-metabolic health, i.e., anthropometric indices, biomarkers of lipid and sugar metabolism, and C-reactive protein levels. There was a positive correlation between water fluoride content and plasma fluoride concentrations (Spearman’s r = 0.41, p < 0.01). However, multivariable linear regression models did not show significant differences in adjusted mean values of systolic and diastolic blood pressure across increasing quartiles of fluoride concentrations. Further markers of cardio-metabolic health were not associated with fluoride status, with the exception of a weak inverse association between plasma fluoride and HbA1c levels. Higher plasma fluoride may not be a risk factor for increased blood pressure or impaired cardio-metabolic health among children in the USA, a non-fluoride endemic country, with wide-spread water fluoridation.

Association between fluoride exposure and blood pressure in children and adolescents aged 6 to19 years in the United States: NHANES, 2013–2016

ABSTRACT To examine the association between fluoride exposure and childhood blood pressure (BP), we used data involving 3260 subjects participating in the National Health and Nutrition Examination Survey (NHANES) from 2013 to 2016. Both plasma and water fluoride concentrations were measured using the ion-specific electrode. Outcome variables were systolic blood pressure (SBP) and diastolic blood pressure (DBP). For a 1-mg/L increase in water fluoride concentration, the participantsʻ SBP decreased by 0.473 mm Hg (95% CI: −0.860, −0.087). Specifically, inverse associations were found between water fluoride and SBP in girls (β= −0.423, 95% CI: −0.886, −0.021), adolescents (β= −0.623, 95% CI: −0.975, −0.272), and non-Hispanic whites (β= −0.694, 95% CI: −1.237, −0.151). Also, every 1-μmol/L increase in plasma fluoride concentration was associated with a 1.183 mm Hg decrease in SBP among other races (95% CI: −2.258, −0.108). This study suggested that fluoride exposure may affect childhood blood pressure.

Fluoride Exposure and Age of Menarche: Potential Differences Among Adolescent Girls and Women in the United States

Fluoride exposure is associated with later pubertal development and decreased testosterone production in adolescent and adult males. However, its effects on female reproductive health and pubertal development are unclear. Therefore, we examined associations of fluoride exposure with reproductive health outcomes among adolescent girls and women in the United States. Participants were from The National Health and Nutrition Examination Surveys (2013 to 2016), aged 16–19 and identified as female. There were 524 and 460 participants with measures of plasma fluoride and household tap water fluoride respectively, who had at least one reproductive health outcome examined, and complete covariate data. We applied covariate adjusted survey-weighted linear or logistic regression to examine associations of fluoride exposure with age of menarche, menstrual cycle regularity, or serum sex steroid hormone levels. Median interquartile range (IQR) water and plasma fluoride concentrations were 0.48 (0.53) mg/L and 0.34 (0.30) µmol/L respectively. An IQR increase in water fluoride was associated with a 3.3 month earlier first menstrual period (B = − 0.28, 95%CI − 0.54, − 0.02, p = 0.05). Additionally, we observed a significant interaction between plasma fluoride and race/ethnicity in association with age of menarche (p = 0.01). Among Non-Hispanic Black adolescents, each IQR increase in plasma fluoride was associated with a 5-month earlier age of menarche (B = − 0.42, 95%CI − 0.61, − 0.23, p < 0.001). Potential impacts of chronic low-level fluoride exposure on reproductive health outcomes are an important area of study. Current study findings, as well as potential health disparities due to disproportionate fluoride exposure should be examined in prospective studies.

Soluble Fluoride in Na2FPO3/CaCO3-Based Toothpaste as an Indicator of Systemically Bioavailable Fluoride

Fluoride chemically soluble in toothpaste is an indicator of fluoride bioavailability when the teeth are brushed, and the same should be expected systemically when toothpaste is ingested. A 4-phases study was conducted, in which 8 participants were subjected in each phase to one of the assigned treatment groups: group I: fresh sample of a Na₂FPO₃/CaCO₃ toothpaste with 1,334 μg F/g of total soluble fluoride (TSF) and groups II–IV: aged samples of toothpaste presenting TSF concentrations of 1,128, 808, and 687 μg F/g, respectively. In all phases, the participants ingested an amount of toothpaste equivalent to 70.0 μg F/kg body weight, as total fluoride (TF). Blood was collected before (baseline) and up to 180 min after toothpaste ingestion as indicator of fluoride bioavailability. Total urine (24 h before and 24 h after ingestion) was collected as indicator of absorbed fluoride that was excreted. F concentration in blood plasma and urine was determined with a fluoride ion-specific electrode. The areas under the curve (AUC) of F concentration versus time (AUC = ng F/mL × min) and the peaks of fluoride concentration in blood plasma (C_max) were calculated. The net amount of fluoride excreted (mg/day) was calculated by subtraction. A significant correlation of the amount (mg) of TSF ingested was found between the AUC (r = 0.76; p < 0.01) and C_max (r = 0.86; p < 0.01) in plasma, and the fluoride excreted (r = 0.65; p < 0.01). For TF, no statistical correlations were found (p > 0.05). Data suggest that the concentration of TSF found in Na₂FPO₃/CaCO₃-based toothpastes is a useful predictor of how much fluoride will be systemically bioavailable when this type of formulation is ingested.

Serum Concentration of Fluoride in Patients with Alcoholic Liver Cirrhosis from the Lublin Region in Eastern Poland.

In view of previous reports, it is important to determine the relationship between liver function and the level of fluoride in the serum. The aim of this study was to investigate serum concentrations of fluoride in 72 patients with alcoholic liver cirrhosis, living in the region of Lublin (Eastern Poland) divided based on the severity of disease according to the Child-Turcotte-Pugh criteria. Higher plasma fluoride concentrations were associated with changes in liver related parameters. In all groups of analyzed patients with different stages of alcoholic liver cirrhosis, elevated levels of plasma fluoride and increased activities of both alanine aminotransferase (ALT) and total bilirubin concentration were shown.

Predictors of Plasma Fluoride Concentrations in Children and Adolescents.

Despite increasing concerns about neurotoxicity of fluoride in children, sources of fluoride exposure apart from municipal water fluoridation are poorly understood. We aimed to describe the associations of demographics, drinking water characteristics, diet, and oral health behaviors with plasma fluoride concentrations in U.S. children. We used data from 3928 6–19-year-olds from the 2013–2016 National Health and Nutrition Examination Survey. We used a 24-h dietary recall to estimate recent consumption of fluoridated tap water and select foods. We estimated the associations of fluoridated tap water, time of last dental visit, use of toothpaste, and frequency of daily tooth brushing with plasma fluoride concentrations. The participants who consumed fluoridated (≥0.7 mg/L) tap water (n = 560, 16%) versus those who did not had 36% (95% CI: 22, 51) higher plasma fluoride. Children who drank black or green tea (n = 503, 13%) had 42% higher plasma fluoride concentrations (95% CI: 27, 58) than non-tea drinkers. The intake of other foods and oral health behaviors were not associated with plasma fluoride concentrations. The consumption of fluoridated tap water and tea substantially increases plasma fluoride concentrations in children. Quantifying the contribution of diet and other sources of fluoride is critical to establishing safe target levels for municipal water fluoridation.

Plasma and water fluoride levels and hyperuricemia among adolescents: A cross-sectional study of a nationally representative sample of the United States for 2013–2016

Exposure to excessive fluoride has been associated with a number of adverse health outcomes; however, there is a lack of evidence on the relation between fluoride exposure and serum uric acid levels, especially in human populations. The present study examined a potential relationship between fluoride exposure, measured as both plasma and water fluoride concentrations, and uric acid levels in an adolescent population. A nationally representative subsample of 1933 adolescents, aged 12–19 years, in the 2013–2016 National Health and Nutrition Examination Survey was analyzed for the association of fluoride concentrations with serum uric acid levels using multivariate general linear and logistic regression models, adjusting for potential confounders. Since uric acid levels change during development, hyperuricemia was defined in this study as over the mean plus one standard deviation for each sex and age group of adolescents. Of the study participants, 276 adolescents (weighted prevalence, 16.56%) had hyperuricemia. A significant and dose-dependent increase in prevalence of hyperuricemia was seen among the participants cross increasing quartiles of plasma fluoride (p-trend = 0.0017). After adjusting for potential confounders, we found that adolescents in the higher quartiles of plasma fluoride (≥0.32 µmol/L) and in the highest quartile of water fluoride (≥0.73 mg/L) had significantly increased odds of hyperuricemia compared with those in the lowest quartile. A 1.95-fold increased odds (95% CI: 1.37, 2.77) of hyperuricemia was also observed when analyzing plasma fluoride concentrations as continuous variable. A general linear model revealed that a 1 µmol/L increase in ln-plasma fluoride was associated with a 0.212 mg/dL (p < 0.0001) increased serum uric acid level. Furthermore, a positive relationship was observed between water and plasma fluoride concentrations (β = 0.1907; p < 0.0001). Our study demonstrates a potential relation between fluoride exposure and hyperuricemia in adolescents. Further studies are warranted to overcome the limitations of this study to examine the impact of long-term exposure to low levels of fluoride during development on hyperuricemia and its related health outcomes.

Biomarkers for the Assessment of Fluoride Exposure in Children

Due to practical difficulties in quantifying fluoride exposure, the ability of various biomarkers to predict exposure has been investigated previously. However, the results are inadequate for validation of their application and usefulness. This study aimed to investigate the association between contemporary/recent biomarkers of fluoride exposure and total daily fluoride intake (TDFI) of children with large differences in fluoride exposure through drinking water. TDFI was assessed in 61 healthy 4- to 5-year-old children who provided at least 1 biomarker sample; 32 lived in a low-fluoride area (0.04 mg F/L) and 29 lived in a high-fluoride area (3.05 mg F/L). Validated questionnaires were administered to evaluate fluoride intake from diets (including water) and toothpaste ingestion. Daily urinary fluoride excretion (UFE) and fluoride concentrations in plasma, fasting whole saliva, hair, and nails (toenails/fingernails) were evaluated and related to total fluoride exposure. TDFI, UFE, and fluoride concentrations of biomarkers were statistically significantly higher in the high-fluoride area than in the low-fluoride area. There was a strong statistically significant positive correlation between TDFI and UFE (ρ = 0.756, p < 0.001); plasma fluoride concentration (ρ = 0.770, p < 0.001); and toenail fluoride concentration (ρ = 0.604, p < 0.001). The statistically significant positive correlation between TDFI and fingernail fluoride concentration (ρ = 470, p < 0.001) as well as between TDFI and fasting whole saliva fluoride concentration (ρ = 0.453, p = 0.001) was moderate, whereas it was weak between TDFI and hair fluoride concentration (ρ = 0.306, p = 0.027). In conclusion, the current study confirmed the suitability of 24-h urine samples for estimating fluoride exposure in children. The strong correlations between TDFI and fluoride in plasma and toenails also suggest these biomarkers may be considered for health risk assessments of fluoride in children who are susceptible to development of dental fluorosis.

Fluoride exposure and sleep patterns among older adolescents in the United States: a cross-sectional study of NHANES 2015\u20132016

BackgroundFluoride from environmental sources accumulates preferentially in the pineal gland which produces melatonin, the hormone that regulates the sleep-wake cycle. However, the effects of fluoride on sleep regulation remain unknown. This population-based study examined whether chronic low-level fluoride exposure is associated with sleep patterns and daytime sleepiness among older adolescents in the United States (US).MethodThis cross-sectional study utilized data from the National Health and Nutrition Examination Survey (2015–2016). We analyzed data from adolescents who had plasma fluoride (n = 473) and water fluoride (n = 419) measures and were not prescribed medication for sleep disorders. Relationships between fluoride exposure and self-reported sleep patterns or daytime sleepiness were examined using survey-weighted linear, binomial logistic or multinomial logistic regression after covariate adjustment. A Holm-Bonferroni correction accounted for multiple comparisons.ResultsThe average age of adolescents was 17 years (range = 16–19). Median (IQR) water and plasma fluoride concentrations were 0.27 (0.52) mg/L and 0.29 (0.19) μmol/L respectively. An IQR increase in water fluoride was associated with 1.97 times higher odds of reporting symptoms suggestive of sleep apnea (95% CI: 1.27, 3.05; p = 0.02), a 24 min later bedtime (B = 0.40, 95% CI: 0.10, 0.70; p = 0.05), a 26 min later morning wake time (B = 0.43, 95% CI: 0.13, 0.73; p = 0.04), and among males, a 38% reduction in the odds of reporting snoring (95% CI: 0.45, 0.87, p = 0.03).ConclusionsFluoride exposure may contribute to changes in sleep cycle regulation and sleep behaviors among older adolescents in the US. Additional prospective studies are warranted to examine the effects of fluoride on sleep patterns and determine critical windows of vulnerability for potential effects.

Association between fluoride exposure and cardiometabolic risk in peripubertal Mexican children

BackgroundSeveral animal studies have suggested that fluoride exposure may increase the levels of cardiometabolic risk factors, but little is known about whether fluoride exposure is associated with such risk in humans. ObjectivesWe examined the cross-sectional association between peripubertal exposure to fluoride and markers of cardiometabolic risk in 280 girls and 256 boys at age 10–18 years living in Mexico City. MethodsWe measured plasma fluoride concentration using a microdiffusion method. We collected data on anthropometry including BMI, waist circumference (WC) and trunk fat percentage. We measured serum markers of cardiometabolic risk, including fasting glucose, insulin and lipids. All the indicators of outcome were converted to age- and sex-specific z-scores. We also calculated a summary cardiometabolic risk score for each participant. Multivariable linear regression models were used to examine these associations. ResultsThe geometric mean (95% confidence interval (CI)) of plasma fluoride was 0.21 μmol/L (0.20, 0.23 μmol/L) in the total sample. In girls, plasma fluoride concentrations were associated with higher z-scores for all the individual markers (except for lipids) and for the combined cardiometabolic risk score (risk score: β = 1.28, 95% CI: 0.57–2.00, p-sex interaction = 0.02)), adjusting for covariates. No associations were found in boys. ConclusionsWe found that higher peripubertal fluoride exposure at the levels observed in this study population was significantly associated with increased levels of cardiometabolic risk factors in Mexican girls but not boys. Future studies with a longitudinal design are needed to confirm our findings and further elucidate the role of fluoride in cardiometabolic risk.

Associations of dietary factors and oral health behaviors with plasma fluoride concentrations in children and adolescents aged 6 to 19 years

Associations of dietary factors and oral health behaviors with plasma fluoride concentrations in children and adolescents aged 6 to 19 years

Fluoride exposure and kidney and liver function among adolescents in the United States: NHANES, 2013–2016

BackgroundHepato- and nephrotoxicity of fluoride have been demonstrated in animals, but few studies have examined potential effects in humans. This population-based study examines the relationship between chronic low-level fluoride exposure and kidney and liver function among United States (U.S.) adolescents. This study aimed to evaluate whether greater fluoride exposure is associated with altered kidney and liver parameters among U.S. youth. MethodsThis cross-sectional study utilized data from the National Health and Nutrition Examination Survey (2013–2016). We analyzed data from 1983 and 1742 adolescents who had plasma and water fluoride measures respectively and did not have kidney disease. Fluoride was measured in plasma and household tap water. Kidney parameters included estimated glomerular filtration rate (calculated by the original Schwartz formula), serum uric acid, and the urinary albumin to creatinine ratio. Liver parameters were assessed in serum and included alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, blood urea nitrogen, gamma-glutamyl transferase, and albumin. Survey-weighted linear regression examined relationships between fluoride exposure and kidney and liver parameters after covariate adjustment. A Holm-Bonferroni correction accounted for multiple comparisons. ResultsThe average age of adolescents was 15.4 years. Median water and plasma fluoride concentrations were 0.48 mg/L and 0.33 μmol/L respectively. A 1 μmol/L increase in plasma fluoride was associated with a 10.36 mL/min/1.73 m2 lower estimated glomerular filtration rate (95% CI: −17.50, −3.22; p = 0.05), a 0.29 mg/dL higher serum uric acid concentration (95% CI: 0.09, 0.50; p = 0.05), and a 1.29 mg/dL lower blood urea nitrogen concentration (95%CI: −1.87, −0.70; p < 0.001). A 1 mg/L increase in water fluoride was associated with a 0.93 mg/dL lower blood urea nitrogen concentration (95% CI: −1.44, −0.42; p = 0.007). ConclusionsFluoride exposure may contribute to complex changes in kidney and liver related parameters among U.S. adolescents. As the study is cross-sectional, reverse causality cannot be ruled out; therefore, altered kidney and/or liver function may impact bodily fluoride absorption and metabolic processes.

Concentrations of fluoride in water and plasma for US children and adolescents: Data from NHANES 2013-2014.

For the first time, for 2013-2014, as part of ongoing National Health and Nutrition Examination Survey, data for fluoride concentrations in water and plasma for U.S. children and adolescents were released in the public domain. This study was undertaken to investigate how fluoride concentrations vary in water and plasma with age, gender, race/ethnicity, housing ownership, use of prescription fluoride drops and/or tablets, exposure to environmental tobacco smoke, and recent use of tobacco products (among adolescents). Fluoride concentrations in water were found to be lower among those aged 3-5 years than those aged 6-11 years (p=0.02), lower for non-Hispanic Asians than Hispanics (p=0.04) among 3-5 years old, lower for non-Hispanic Asians than non-Hispanic blacks (p=0.04) among 6-11 years old, and lower for those who used prescription fluoride drops and/or tablets than those who did not (p≤0.048) among 12-19 years old. Adjusted fluoride concentrations in plasma were found to be lower for females than males (p<0.01) among those aged 6-11 years, lower for Hispanics than non-Hispanic whites (p<0.01) among those aged 12-19 years, and lower for those who used prescription fluoride drops and/or tablets than those who did not (p=0.03) among 12-15 years old. Recent smokers were found to have higher fluoride concentration (p=0.03) in plasma than non-smoker adolescents. Over 60% of the children aged 6-11 years and adolescents aged 12-19 years were at the risk of developing dental caries/decay. About 30% of the children were at the risk of dental fluorosis.

Trace Minerals and Biochemical Profile in Buffalo Calves Manifesting Coat Colour Depigmentation in the Fluoride Endemic South-West Punjab

The present work aimed to study trace minerals and haemato-biochemical profile of buffalo calves manifesting depigmentation of coat colour (depigmented calves: DC) in comparison to calves having normal coat colour (normal calves: NC) in the fluoride endemic zone of the South-West Punjab. Plasma fluoride concentrations in NC and DC were higher than the normal but it did not vary between the groups. Plasma copper concentration in DC was lower than the critical limit of 0.70 μgml−1 and it was significantly (p<0.05) lower as compared to NC. Hair copper and plasma ceruloplasmin activity did not vary between the groups. Plasma molybdenum, and plasma and hair zinc and manganese concentrations were normal and did not vary between the groups. Plasma iron concentrations in both the groups were higher than the physiological limit of 2.50 μgml−1. The hair iron concentrations were significantly (p<0.05) higher in DC. The Hb, PCV, TEC, serum total proteins, albumin, globulin, plasma urea nitrogen, creatinine, glucose, cholesterol, triglycerides, ALP, AST, CK and GGT were normal in both the groups. It is concluded that depigmentation of coat colour in buffalo calves from the fluoride endemic South-west Punjab is due to deficiency of copper.

Assessment of the Influence of Meal Type on Fluoride Absorption due to Ingestion of professionally Applied Gels.

The aim of this study is to assess the influence of eating, prior to application of professionally used gels, on the rate of fluoride absorption due to the ingestion of 1.23% acidulated phosphate fluoride (APF). After fasting for 12 hours, 16 adult volunteers (> 65 kg) ingested two types of meal: Breakfast (n = 8) and Lunch (n = 8). Accidental ingestion of fluoride gel used in molding trays was simulated (12,300 ppm; 61.5 mg F; pH = 4.65) 15 minutes after eating. After ingestion of the fluoride solution, 3 mL of venous blood were collected at the following times: Zero (before ingestion) and 15, 30, 45 minutes, 1, 2, and 3 hours. Fluoride concentrations in blood plasma were determined using an ion selective electrode. With the exception of time 0 (p > 0.05), the average blood plasma concentration of the breakfast group (BG) (0.34 ± 0.04 mg/L) was higher than that of the lunch group (LG) (0.24 ± 0.03 mg/L), with the moment of peak concentration being 2 hours after ingestion for both groups (BG = 0.4 mg/L; LG = 0.28 mg/L). Results reinforce the idea that eating before undergoing professional application of fluoride is a factor of extreme importance regarding its safety, and that the time following a patient's heaviest meal should be the time of choice for planning clinical care. Our results should be considered when planning collective action that involves the application of the gel on children in a school environment, thus ensuring the procedure's safety.