Urinary Fluoride Concentration Research Articles

Serum calcium improves the relationship between fluoride exposure and hypothalamic-pituitary-testicular axis hormones levels in males—a cross-sectional study on farmers in the lower reaches of the Yellow River

Numerous studies have reported the toxicity of fluoride to the male reproductive system, but epidemiological evidence is limited. We conducted a cross-sectional study in Kaifeng City, Henan Province in 2011 to explore the association between fluoride exposure and hypothalamic-pituitary-testicular (HPT) axis hormones in men. Morning urinary fluoride (UF), serum HPT axis hormones and serum calcium (SC) concentrations were detected. Percent changes and 95% confidence intervals in HPT axis hormones associated with UF were estimated using adjusted linear regression models, and performed subgroup analysis based on SC levels. The restricted cubic spline model was used to fit nonlinear relationships. For every 10% increase in UF, the concentrations of serum GnRH, T, SHBG and TSI decreased by 2.13%, 2.39%, 2.19% and 1.96%, while E2 and FEI increased by 1.11% and 3.33%. Subgroup analysis showed that for every 10% increase in UF, the levels of GnRH, T, TSI and FTI decreased by approximately 3.15%, 5.49%, 4.47% and 5.14%, while the E2 level increased by 2.92% in low-serum-calcium group (LCG). The levels of GnRH and T decreased by approximately 2.97% and 1.82% in medium-serum-calcium group (MCG). In high-serum-calcium group (HCG), serum SHBG levels decreased by 4.70%, while FTI and FEI levels increased by 4.93% and 4.20% as UF concentration increased (P < 0.05, respectively). The non-linear relationship between serum GnRH and UF concentrations presented an approximately inverted U-shaped curve, with a turning point UF concentration of 1.164 mg/L (P < 0.001), and their nonlinear relationship in LCG and MCG were similar to that in the overall subjects. In conclusion, excessive exposure to fluoride can interfere with male serum HPT axis hormones, and a moderate increase in SC alleviates the effect of fluoride. Prospective cohort studies are essential to confirm the causality.

Gut microbiome and function are altered for individuals living in high fluoride concentration areas in Pakistan

BackgroundEndemic fluorosis refers to the condition when individuals are exposed to excessive amounts of fluoride ion due to living in a region characterized by elevated levels of fluorine in the drinking water, food, and/or air. In Pakistan, a substantial proportion of the population is thereby affected, posing a public health concern. ObjectivesAssessing how the gut microbiota and its metabolic profiles are impacted by chronic exposure to fluoride in drinking water (that caused Dental Fluorosis) as well as to perceive how this microbiota is connected to adverse health outcomes prevailing with fluoride exposure. MethodsDrinking water (n=27) and biological samples (n=100) of blood, urine and feces were collected from 70 high fluoride exposed (with Dental Fluorosis) and 30 healthy control (without Dental Fluorosis) subjects. Water and urinary fluoride concentrations were determined. Serum/plasma biochemical testing was performed. Fecal DNA extraction, 16S rRNA analysis of microbial taxa, their predicted metabolic function and fecal short chain fatty acids (SCFAs) quantification were carried out. ResultsThe study revealed that microbiota taxonomic shifts and their metabolic characterization had been linked to certain host clinical parameters under the chronic fluoride exposure. Some sets of genera showed strong specificity to water and urine fluoride concentrations, Relative Fat Mass index and SCFAs. The SCFAs response in fluoride-exposed samples was observed to be correlated with bacterial taxa that could contribute to adverse health effects. ConclusionsMicrobial dysbiosis as a result of endemic fluorosis exhibits a structure that is associated with risk of metabolic deregulation and is implicated in various diseases. Our results may form the development of novel interventions and may have utility in diagnosis and monitoring.

Salivary proteomic signatures in severe dental fluorosis

The relationship between dental fluorosis and alterations in the salivary proteome remains inadequately elucidated. This study aimed to investigate the salivary proteome and fluoride concentrations in urine and drinking water among Thai individuals afflicted with severe dental fluorosis. Thirty-seven Thai schoolchildren, aged 6–16, were stratified based on Thylstrup and Fejerskov fluorosis index scores: 10 with scores ranging from 5 to 9 (SF) and 27 with a score of 0 (NF). Urinary and water fluoride levels were determined using an ion-selective fluoride electrode. Salivary proteomic profiling was conducted via LC–MS/MS, followed by comprehensive bioinformatic analysis. Results revealed significantly elevated urinary fluoride levels in the SF group (p = 0.007), whereas water fluoride levels did not significantly differ between the two cohorts. Both groups exhibited 104 detectable salivary proteins. The NF group demonstrated notable upregulation of LENG9, whereas the SF group displayed upregulation of LDHA, UBA1, S100A9, H4C3, and LCP1, all associated with the CFTR ion channel. Moreover, the NF group uniquely expressed 36 proteins, and Gene Ontology and pathway analyses suggested a link with various aspects of immune defense. In summary, the study hypothesized that the CFTR ion channel might play a predominant role in severe fluorosis and highlighted the depletion of immune-related salivary proteins, suggesting compromised immune defense in severe fluorosis. The utility of urinary fluoride might be a reliable indicator for assessing excessive fluoride exposure.

Combining Network Pharmacology and Experimental Verification to Ascertain the Mechanism of Action of Asparagus officinalis Against the Brain Damage Caused by Fluorosis.

Asparagus officinalis (ASP) has antioxidation, anti-inflammatory, antiaging, and immune system-enhancing effects. We explored the preventive and therapeutic consequences of ASP on the brain damage elicited by fluorosis through network pharmacology and in vivo experimental validation. We ascertained the pharmaceutically active ingredients and drug targets of ASP from the Traditional Chinese Medicine Systems Pharmacology database, predicted the disease targets of fluorosis-induced brain injury using GeneCards and Online Mendelian Inheritance in Man databases, obtained target protein-protein interaction networks in the Search Tool for the Retrieval of Interacting Genes/Proteins database, used Cytoscape to obtain key targets and active ingredients, and conducted enrichment analyses of key targets in the Database for Annotation, Visualization and Integrated Discovery. Enrichment analyses showed that "mitogen-activated protein kinase" (MAPK), "phosphoinositide 3-kinase/protein kinase B" (PI3K-Akt), "nuclear factor-kappa B" (NF-κB), and the "neurotrophin signaling pathway" were the most enriched biological processes and signaling pathways. ASP could alleviate fluorosis-based injury, improve brain-tissue damage, increase urinary fluoride content, and improve oxidation levels and inflammatory-factor levels in the body. ASP could also reduce dental fluorosis, bone damage, fluoride concentrations in blood and bone, and accumulation of lipid peroxide. Upon ASP treatment, expression of silent information regulator (SIRT)1, brain-derived neurotrophic factor (BDNF), tropomyosin receptor kinase B (TrkB), MAPK, NF-κB, PI3K, Akt, and B-cell lymphoma-2 in rat brain tissue increased gradually, whereas that of Bax, caspase-3, and p53 decreased gradually. We demonstrated that ASP could regulate the brain damage caused by fluorosis through the SIRT1/BDNF/TrkB signaling pathway, and reported the possible part played by ASP in preventing and treating fluorosis.

A Bayesian benchmark concentration analysis for urinary fluoride and intelligence in adults in Guizhou, China

Environmental fluoride exposure has been linked to numerous cases of fluorosis worldwide. Previous studies have indicated that long-term exposure to fluoride can result in intellectual damage among children. However, a comprehensive health risk assessment of fluorosis-induced intellectual damage is still pending. In this research, we utilized the Bayesian Benchmark Dose Analysis System (BBMD) to investigate the dose-response relationship between urinary fluoride (U-F) concentration and Raven scores in adults from Nayong, Guizhou, China. Our research findings indecate a dose-response relationship between the concentration of U-F and intelligence scores in adults. As the benchmark response (BMR) increased, both the benchmark concentration (BMCs) and the lower bound of the credible interval (BMCLs) increased. Specifically, BMCs for the association between U-F and IQ score were determined to be 0.18 mg/L (BMCL1 = 0.08 mg/L), 0.91 mg/L (BMCL5 = 0.40 mg/L), 1.83 mg/L (BMCL10 = 0.83 mg/L) when using BMRs of 1 %, 5 %, and 10 %. These results indicate that U-F can serve as an effective biomarker for monitoring the loss of IQ in population. We propose three interim targets for public policy in preventing interllectual harm from fluoride exposure.

Correlations between bone metabolism biomarkers and fluoride exposure in adults and children

Increased exposure to fluoride, which notably affects bone metabolism, is a global concern. However, the correlations and sensitivity of bone metabolism to fluoride remain controversial. In this cross-sectional study, 549 children (aged 7–12 years) and 504 adults (≥ 18 years old) were recruited in the high-fluoride areas of the Henan Province. Urinary fluoride (UF) level was determined using a fluoride electrode. Fasting venous blood serum was collected to measure bone metabolism biomarkers. The selected bone metabolism biomarkers for children included bone alkaline phosphatase (BALP), serum alkaline phosphatase (ALP), osteocalcin (OCN), calcitonin (CT), parathyroid hormone (PTH), phosphorus (P5+), and calcium (Ca2+). For adults, the biomarkers included ALP, CT, PTH, β-CrossLaps (β-CTX), P5+, and Ca2+. The correlations between UF and bone metabolism biomarkers were analyzed using binary logistic regression, a trend test, a generalized additive model, and threshold effect analysis. Regression analysis indicated a significant correlation between serum OCN, PTH, and UF levels in children aged 7–9 years. Serum OCN, PTH, and BALP contents were significantly correlated with UF in boys (P < 0.05). Furthermore, the interaction between age and UF affected serum P5+ and PTH (P < 0.05). The generalized additive model revealed nonlinear dose–response relationships between P5+, BALP, and UF contents in children (P < 0.05). Serum OCN level was linearly correlated with the UF concentration (P < 0.05). Similarly, a significant correlation was observed between β-CTX and UF levels in adults. In addition, significant correlations were observed between UF–age and serum Ca2+, β-CTX, and PTH contents. There was a non-linear correlation between serum Ca2+, P5+, and β- CTX and UF levels (P < 0.05). Overall, serum OCN, BALP, and P5+ levels can serve as sensitive bone metabolism biomarkers in children, while β-CTX, P5+, and Ca2+ can be considered fluoride-sensitive bone metabolism biomarkers in adults.

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.

Association between urinary fluoride concentrations and the prevalence of metabolic syndrome in adult individuals from the Central Region of Mexico

ABSTRACT Emerging scientific studies have supported the hypothesis that exposure to environmental chemicals increases the incidence of diverse human metabolic disorders. Therefore, this study aimed to evaluate the association between fluoride exposure and metabolic syndrome (MetS) prevalence in people from the Central Region of Mexico. This research included 575 adult individuals. Urinary fluoride concentrations were determined using a potentiometric method. Anthropometric measurements and blood pressure were also acquired. Serum fasting glucose and lipid levels were quantified. For the MetS screening, we used the International Diabetes Federation (IDF) and National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria. The mean urinary fluoride levels were 3.50 ± 2.50 mg/L. The prevalence of MetS was approximately 27 and 25% according to NCEP ATP III and IDF criteria, respectively. A multivariate logistic regression analysis showed significant associations (p < 0.05) between urinary fluoride concentrations and MetS occurrence using NCEP ATP III criteria (OR = 1.60; 95% CI 1.05–2.10) and IDF criteria (OR = 1.35; 95% CI 0.95–1.45). These findings emphasize the need to discover the underlying mechanisms that fluoride exposure has on MetS pathogenesis.

Chronic Fluoride Exposure Induces Ovarian Dysfunction and Potential Association with Premature Ovarian Failure in Female Rats.

Chronic fluorosis has been widely investigated for its adverse effects on skeletal and neurological health; however, its impact on reproductive health, especially in females, remains underexplored. In this study, female Sprague-Dawley rats were exposed to different fluoride concentrations (0.75, 50, and 100mg/L) in their drinking water for six months. Dental fluorosis and increased urinary fluoride content were observed in fluoride-exposed rats, reflecting fluoride accumulation and exposure levels. Chronic fluorosis resulted in reduced ovary organ coefficient, indicating harmful effects on ovarian tissue. Additionally, the number of ovarian primordial and primary/secondary follicles decreased, while the number of atresia follicles increased. Furthermore, chronic fluorosis led to disrupted estrous cycles. Hormonal analysis revealed altered secretion of estrogen, progesterone, anti-Müllerian hormone, luteinizing hormone, follicular stimulating hormone, and inhibin B in response to fluoride exposure. Ultrastructural observation of ovarian granulosa cells showed evidence of apoptosis, which was further confirmed by flow cytometry. Caspase-3 activity was increased, and ATP levels were decreased, suggesting mitochondrial impairment and apoptosis induction. The mRNA and protein expression of BMP15 and GDF9, essential regulators of ovarian function, significantly decreased with increasing fluoride concentration. Furthermore, gene expression analysis identified a panel of premature ovarian failure-related genes that were downregulated in fluoride-exposed rat ovaries. These findings suggest that chronic fluoride exposure may contribute to ovarian dysfunction and possibly the pathogenesis of premature ovarian failure. Understanding the toxicological effects of chronic fluoride exposure on ovarian function is essential for identifying potential environmental risk factors affecting female reproductive health.

Association between ADAMTS14_rs4747096 gene polymorphism and bone mineral density of Chinese Han population residing in fluorine exposed areas in ShanXi Province, China.

This study aimed to investigate the effects of fluorine and ADAMTS14_rs4747096 on bone mineral density (BMD). The survey was explored in a cross-sectional case-control study conducted in Shanxi, China. The BMD was measured by an ultrasonic bone mineral density instrument. The urine fluoride concentration was detected using the fluoride ion electrode. ADAMTS14_rs4747096 polymorphism was examined by multiplex polymerase chain reaction (PCR) and sequencing. The multinomial logistic regressions found that the urine fluoride was a risk factor for osteopenia (OR = 1.379, 95% CI: 1.127-1.687, P = 0.0018), osteoporosis (OR = 1.480, 95% CI: 1.1138-1.926, P = 0.0035), and rs4747096 AG + GG genotype increased the risk of osteoporosis (OR = 2.017, 95% CI: 1.208-3.369, P = 0.0073). In addition, the interaction between urine fluoride and rs4747096 polymorphism on the risk of decreased BMD also was observed. The study suggests that fluoride exposure and mutation G allele in ADAMTS14_rs4747096 may be risk factors for the decrease of BMD. And there is an interaction between the two influencing factors.

Association of Dental Fluorosis and Urinary Fluoride with Intelligence among Schoolchildren.

Fluoride is present naturally in water and has been used worldwide for the prevention of caries. Several studies conducted in high water fluoride or endemic fluorosis areas reported that fluoride adversely affected children's cognitive function, but some studies had negative findings. This study aimed to assess the relationship between urinary fluoride, dental fluorosis, and intelligence among schoolchildren living in communities with non-fluoridated drinking water. This cross-sectional study was conducted on 562 children aged 6-12 years in Taichung, Taiwan. Each child's urinary fluoride level was determined by a fluoride-ion-selective electrode, and the dental fluorosis condition was evaluated according to the criteria of Dean's Index. The Raven's Colored Progressive Matrices-Parallel and Standard Progressive Matrices-Parallel were used to assess children's intelligence. The results showed that the mean (±standard deviation) urinary fluoride concentrations were 0.40 ± 0.27 mg/L (0.43 ± 0.23 mg/g creatinine) among participants. The prevalence of dental fluorosis was 23.67%. After extensive evaluation of potential confounders, dental fluorosis and urinary fluoride were not associated with intelligence quotient (IQ) scores or grades in the regression models. In conclusion, dental fluorosis and urinary fluoride levels were not significantly related to the IQ of schoolchildren living in areas with low drinking water fluoride.

Association between polymorphism and haplotype of ATP2B1 gene and skeletal fluorosis in Han population

ABSTRACT To evaluate the association between ATP2B1 gene polymorphisms and skeletal fluorosis, a cross-sectional study was conducted. In China, 962 individuals were recruited, including 342 cases of skeletal fluorosis. Four TP2BA1 polymorphisms (rs2070759, rs12817819, rs17249754, and rs7136259) were analysed. The results suggested that rs17249754 and rs7136259 were associated with skeletal fluorosis. After controlling confounders, the protective effect of GG genotype in rs17249754 was apparent in individuals over 45 years old, female, with urine fluoride concentration below 1.6 mg/L, serum calcium above 2.25 mmol/L or serum phosphorus between 1.1 and 1.3. Heterozygote TC in rs7136259 increased the risk of skeletal fluorosis in subjects who are elderly, female, with urinary fluoride more than 1.6 mg/L, serum calcium more than 2.25 mmol/L and blood phosphorus between 1.1 and 1.3 mmol/L. Four loci were found to be tightly related by linkage disequilibrium analysis, and the frequency of distribution of haplotype GCGT was lower in the skeletal fluorosis group.

Factors influencing the spatial distribution and individual variation in urinary fluoride levels in Tibet, China

Nowadays, fluorosis is the most prevalent endemic disease in Tibet and one of the most concerned public health problems in China; urinary fluoride is a common diagnostic indicator of endemic fluorosis. However, the spatial distribution and influencing factors of urinary fluoride content in Tibet remain unclear. This study aims to bridge this gap by geographically weighted regression (GWR), analyses of variance (ANOVAs), Geodetector, and stepwise multiple linear regression (MLR). To achieve this goal, this study first investigated fluoride levels in the fasting urine among 637 Tibetan residents from 73 counties in Tibet, the urinary fluoride level was chosen as an indicator of fluorosis, which can reflect the health impairment. Then we identified the potential factors that could influence the spatial distribution and individual variation of urinary fluoride levels from physical environmental and socioeconomic perspective, respectively. The results showed that urinary fluoride levels in Tibet were slightly exceeding the average value for adult urinary fluoride in China, and that residents with high urinary fluoride were mainly found in the west and east; those with low urinary fluoride were mainly found in the central-southern regions. And the urinary fluoride levels had a significantly positive correlation with water fluoride and a significantly negative correlation with average annual temperature. Urinary fluoride levels increased until age 60 and followed an inverted “U”-shaped trajectory according to annual household income (80,000 renminbi (RMB) was the inflection point); pastoralists had greater exposure to fluoride than farmers. Furthermore, the Geodetector and MLR showed that the urinary fluoride level was influenced by both physical environmental and socioeconomic factors. The socioeconomic factors such as age, annual household income and occupation had a greater impact than the physical environment on urinary fluoride concentration. These findings can provide scientific basis for preventing and controlling endemic fluorosis in the Tibetan Plateau and adjacent areas.

Correlation analysis and benchmark dose study on bone metabolic biochemical index of low doses of exposed hydrogen fluoride workers

Objective: To analyze correlation of occupational hydrogen fluoride exposure to low doses of bone metabolism index through occupational epidemiological investigation and benchmark dose calculation. Methods: In May 2021, using cluster sampling method, 237 workers exposed to hydrogen fluoride in a company were selected as the contact group, and 83 workers not exposed to hydrogen fluoride in an electronics production company were selected as the control group. The external exposure dose and urinary fluoride concentration, blood and urine biochemical indicators of the workers was measured.The relationship between external dose and internal dose of hydrogen fluoride was analyzed. The external dose, urinary fluoride was used as exposure biomarkers, while serum osteocalcin (BGP), serum alkaline phosphatase (AKP) and urinary hydroxyproline (HYP) were used as effect biomarkers for bone metabolism of hydrogen fluoride exposure. The benchmark dose calculation software (BMDS1.3.2) was used to calculate benchmark dose (BMD) . Results: Urine fluoride concentration in the contact group was correlated with creatinine-adjusted urine fluoride concentration (r=0.69, P=0.001). There was no significant correlation between the external dose of hydrogen fluoride and urine fluoride in the contact group (r=0.03, P=0.132). The concentrations of urine fluoride in the contact group and the control group were (0.81±0.61) and (0.45±0.14) mg/L, respectively, and the difference between the two groups was statistically significant (t=5.01, P=0.025). Using BGP, AKP and HYP as effect indexes, the urinary BMDL-05 values were 1.28, 1.47 and 1.08 mg/L, respectively. Conclusion: Urinary fluoride can sensitively reflect the changes in the effect indexes of biochemical indexes of bone metabolism. BGP and HYP can be used as early sensitive effect indexes of occupational hydrogen fluoride exposure.

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

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

Estimation of fluoride ion concentration in urine after application of silver diamine fluoride in patients with severe early childhood caries.

Despite the University of California San Francisco, the American Academy of Pediatric Dentistry (AAPD), and the Food and Drug Administration having approved the use of silver diamine fluoride (SDF) in arresting dentinal caries, literature available on its systemic absorption is limited. This study aimed to assess any systemic absorption of fluoride ion following the topical application of SDF in young children. Children aged between 3 and 6 years who were diagnosed with severe early childhood caries and required rehabilitation were recruited for the study. Before the onset of treatment for the arrest and control of caries, a baseline urine sample as a control was collected from the patient. In accordance with the manufacturer's instructions and AAPD guidelines, SDF was topically applied on a minimum of five carious teeth, following which additional urine samples were collected after 2 h and after 24 h, respectively, of application of SDF. The urine samples were stored at -20°C, and the estimation of fluoride ion concentrations in urine was then ascertained using a fluoride ion selective electrode. The results revealed that the fluoride concentration in urine before application of SDF was 0.66 mg/L ± 0.25 mg/L, and following 2 h of application, it was 1.13 mg/L ± 0.23. However, 24 h postapplication, the urinary fluoride concentration was reduced to 0.63 mg/L ± 0.20, which is close to the baseline value of the control sample. There was no significant systemic absorption of fluoride following the application of SDF, and it could be adopted as an effective and safe agent in the armamentarium for managing caries in young children.

Biological Monitoring of Urinary Fluoride Among Phosphate Fertiliser Production Industrial Workers

Objectives: Fluoride pollution at the workplace environment arises mostly due to anthropogenic activities. The workers working in phosphate fertilizer industry might have chronic exposure to excessive fluoride which can cause adverse health effects. Therefore, the present study was designed to assess urinary fluoride levels in occupationally exposed workers. Methods: In this study, pre and post-shift urinary samples were collected from phosphate fertilizer industry male workers (n=53). Fluoride levels in urine samples were analysed using an Ion Selective Electrode (ISE). Findings: The mean concentration of pre-shift and post-shift urinary fluoride levels were 2.141.35 and 2.422.02 mg/g of urinary creatinine respectively. Workers’ pre-shift mean urine fluoride levels were categorised according to their working departments. Workers from the manufacture plat of Single Super Phosphate (SSP), Granular Single Super Phosphate (GSSP), maintenance, and administration had fluoride levels of 2.871.88, 2.431.01, 2.161.30, and 0.920.601 mg/g of urine creatinine, respectively. Similarly, the post-shift urinary fluoride levels were 3.683.00, 2.641.85, 2.241.78 and 1.140.53 mg/g of urinary creatinine in these departments respectively. One-way analysis of variance shown significant difference in urine fluoride concentrations between pre-shift (ANOVA, df=3, F=4.717; p=0.006) and post-shift samples (ANOVA, df=3, F=2.895; p=0.044). About 22.64 % of subjects in the pre-shift and 3.77% of subjects in the post-shift had exceeded the urinary fluoride limits prescribed by various statutory agencies. Novelty: Based on pre-shift and post-shift work exposure assessments, this study adds new knowledge to scientific research on the fluoride exposure among phosphate fertiliser sector workers. While there is sporadic information on fluoride levels among various other occupational groups, very few reports reported the fluoride levels in fertilizer industryworkers. Outcomes of this study will help to identify the source of fluoride and extent of fluoride exposure so as to suggest the mitigation measure to control fluoride exposure at occupational settings. Keywords: Biological monitoring; Fluoride exposure; Urinary fluoride; Occupational fluoride exposure; Fertilizer industry workers

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

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

Fluoride Concentration in Urine after Supplementation with Quelites in a Population of Adolescents.

Wild plants have detoxifying and protective properties. They reduce or neutralize the toxic effects caused by chemical agents and pollutants and have beneficial effects on the nutritional and health status. This research was conducted to complement a previous clinical intervention in which participants were exposed to high concentrations of arsenic and fluoride in drinking water to discover similarities or differences in the pattern of fluoride (F−) excretion after supplementation with partial areas of purslane and quelite cenizo (SP-Q). The study was 4 weeks long, and it was carried out on a sample of 27 adolescents in an age range of 11–12 years. Anthropometric and dietary evaluations were performed, and the concentrations of fluoride (F−) in urine and drinking water were quantified using the potentiometric method with an ion-selective electrode. The treated group increased urinary F− excretion after the first week (Baseline: 9.23 mg/g creatinine; Week 2: 0.73 mg/g creatinine), together with significant mobilization of F− and a recovery process at the end of the intervention (Week 4: 0.52 mg/g creatinine). The supplement may act by increasing the excretion of F− and the nutritional dietary conditions that contribute to mitigation and recovery in participants exposed to the contaminant while also managing access to drinking water.

Waterborne arsenic and fluoride exposure in Mexico: risk assessment and epidemiological research on their health effects

Many aquifers in Mexico contain toxic levels of arsenic and fluoride; still, 39% of the population relies on groundwater for drinking. Our objectives were to evaluate the health risks of fluoride and arsenic in drinking water in central [Cuenca Alta del Río Laja (CARL)] and northern [Comarca Lagunera (CL)] Mexico, and to compare economic and health trade-offs of different aquifer pumping scenarios. In two CARL studies, we measured arsenic and fluoride in drinking water and fluoride in children’s urine; health risks were estimated through hazard quotients (HQ). In 2018 we assessed dental fluorosis (n=39) and in 2019, we measured intelligence quotient (IQ) (n=74). Another study modeled the revenues, costs, health, and income outcomes from increasing, decreasing, or maintaining the aquifer pumping rates over 100 years. The fourth study assessed cancer and non-cancer risks in CL according to arsenic levels in 91 wells. In CARL, children who drank groundwater had an increased fluoride risk of health effects (HQ= 1.5); 82% presented dental fluorosis, and their urine fluoride concentrations increased 0.96 mg/L per 1 mg/L increase in water fluoride (p &amp;#x3c; 0.001). Urine fluoride was negatively associated with IQ (β= -1.12, CI 95% -4.1, 1.8). Assuming increasing aquifer pumping rates in the next 100 years, arsenic and fluoride concentrations would increase to 40 &amp;#x3bc;g/L and 2.1 mg/L, respectively, potentially diminishing IQ by 6 and 7 points, respectively. In CL, 90% of the sampled wells exceeded the WHO’s arsenic drinking water guidelines; the carcinogenic risk ranged from 2.6×10-⁵ to 6.1×10-³. Children in CARL and CL are drinking groundwater with toxic fluoride and arsenic concentrations that increase their cancer and non-cancer health risks to unacceptable levels. The health and economic benefits of mitigating exposure to arsenic and fluoride greatly exceed the benefits of increasing pumping for more agricultural production. Keywords: arsenic, fluoride, water, Mexico