High Levels Of Fluoride Research Articles

A targetable fluorescent probe for real-time monitoring of fluoride ions in mitochondria

Fluorion are pivotal anions in biology because they play an important role in dental care, treating osteoporosis, preventing tooth decay and promoting the healthy growth of bone. Studies have shown that high levels of fluoride will lead to the inactivation of the mitochondria. Therefore, it is urgent to develop a method to detect the fluoride anions in the mitochondria. Herein, we have developed a novel mitochondrial-target fluorescent probe for detecting F− in living cells. The probe exhibited excellent sensitivity and high selectivity for F− over the other relative species. With changing fluoride ions, the fluorescence spectrum of the probe changed significantly with a large turn-on fluorescence signal. Cell imaging indicated that the probe can penetrate viable cell membranes and rapidly detects and images fluorion over other anions in the mitochondria.

On the mechanism controlling fluoride concentration in groundwaters of the south of the Province of Buenos Aires, Argentina: adsorption or solubility?

High levels of fluoride in drinking water affect millions of people due to health problems associated with water consumption. Fluoride concentrations in groundwaters from the unsaturated and saturated zones of a watershed located in the Chaco-Pampean Plain of Argentina are reported and investigated to evaluate the mechanism that controls these concentrations. Two hypotheses were formulated: (a) the adsorption hypothesis, which assumes that fluoride is controlled by adsorption/desorption processes on mineral oxides, and (b) the dissolution hypothesis, which assumes that the solubility of fluorite is the controlling process. Calculations with the CD-MUSIC surface complexation model to test the adsorption hypothesis rendered very poor results. The affinity of fluoride for surface sites is so low that it is easily displaced by carbonate, and thus the calculated fluoride–carbonate trends are very different to the experimentally found with the studied water samples. On the contrary, a comparison of reaction quotients, Q, with equilibrium constants, K, for fluorite dissolution, calcite dissolution and a combination of both processes indicates that fluorite and calcite are in equilibrium or close to equilibrium with their corresponding ions in solution, giving strength to the dissolution hypothesis. This hypothesis can also explain, at least qualitatively, why fluoride correlates positively with arsenate and carbonate. The conclusions could be extrapolated to many other systems worldwide, which present these positive correlations.

GEOCHEMICAL PROVENANCE AND SPATIAL VARIATION OF FLUORIDE IN GROUNDWATER OF SINDHUDURG DISTRICT, WESTERN MAHARASHTRA

The present study focuses on the occurrence and intensity of fluoride in drinking water from the Malvan-Vijaydurg coastal tract in Sindhudurg district, Maharashtra. Concentration of fluoride (F-) from 36 dug wells/bore wells sampled during this study ranged from 0.04 mg/L to 1.6 mg/L. The results indicate that about 47% of the water samples from the study area have fluoride content greater than 1 mg/L, which exceeds the permissible limit of BIS (1 mg/L), while 4 samples exceeded the World Health Organization standards of 1.5 mg/L. Spatial variation in F- concentration indicates that most of the sampling sites having comparatively high fluoride also have high values of pH, EC and TDS concentration measured in groundwater. High fluoride levels are associated with Ca-Mg-Cl-SO4, Na-Cl and Na-HCO3 type water produced by calcite precipitation and/or base ion exchange. The groundwater with higher fluoride concentrations is accompanied by lower Ca+2 levels. This study augments our understanding on geochemical behaviour of F- concentration and highlights the importance of spatial variability of F- in coastal aquifers. It is also pertinent to monitor the water quality periodically in this region and consequently discontinue using the wells which contain high fluoride concentration.

Mus musculus bone fluoride concentration as a useful biomarker for risk assessment of skeletal fluorosis in volcanic areas

Fluoride is often found in elevated concentrations in volcanic areas due to the release of magmatic fluorine as hydrogen fluorine through volcanic degassing. The exposure to high levels of fluoride can affect the processes of bone formation and resorption causing skeletal fluorosis, a pathology that can easily be mistaken for other skeletal diseases. In this study, we aimed to determine if fluoride concentration in the femoral bone of wild populations of the house mouse (Mus musculus) is a good biomarker of exposure to active volcanic environments naturally enriched in fluoride, allowing their use in biomonitoring programs.The fluoride concentration of the whole femoral bone of 9 mice from Furnas (5 males and 4 females) and 33 mice from Rabo de Peixe (16 males and 17 females) was measured by the potentiometric method with a fluoride ion selective electrode.Fluoride in bones was significantly higher in the mice from Furnas when compared with the mice from Rabo de Peixe (616.5 ± 129.3 μg F/g vs. 253.8 ± 10.5 μg F/g). Accumulation rates were also significantly higher in the mice collected in Furnas when compared with Rabo de Peixe individuals (3.84 ± 0.52 μg F/day vs. 1.22 ± 0.06 μg F/day).The results demonstrate a significant association between exposure to fluoride in the active volcanic environment and fluoride content in bone, revealing that bone fluoride concentration is a suitable biomarker of chronic environmental exposure to fluoride.

Association of Hypertension, Body Mass Index, and Waist Circumference with Fluoride Intake; Water Drinking in Residents of Fluoride Endemic Areas, Iran.

Hypertension is becoming a global epidemic for both rural and urban populations; it is a major public health challenge in Iran. Fluoride can be a risk factor for hypertension. Cross-sectional analysis was conducted in two study areas to assess the relation of fluoride with blood pressure prevalence, BMI, waist circumference, and waist-to-hip ratio (WHR) among different age groups in both sexes. The mean value of fluoride concentration in the drinking water from the four study villages varied from 0.68 to 10.30mg/L. The overall prevalence of HTN and prehypertension in all subjects was 40.7%. The prevalence of isolated systolic hypertension, isolated diastolic hypertension, systolic-diastolic hypertension, and prehypertension in the total sample population was 1.15, 0.28, 9.53, and 29.76%, respectively. The odd ratio of hypertension in residents who drank water with high fluoride levels was higher than that in residents who drank water with lower level of fluoride (OR 2.3, 1.03-5.14). Logistic regression results showed that age (P < 0.001), sex (P = 0.018), BMI (P = 0.015), and the fluoride level in drinking water (P = 0.041) had a significant relationship with increased blood pressure. There were no statistically significant correlations between fluoride and BMI, hip circumference, and waist to hip ratio (WHR). The findings of this study are important for health care personnel and policymakers.

Does fluorosis affect the intelligence profile of children? A cross sectional analysis of school children of district Una, Himachal Pradesh, India

Background: The sub Himalayan region of the country does not fall in highly endemic region for fluorosis. Researchers over the world have hypothesized that high fluoride level in water is the cause of low intelligence level among children and adolescents. We aim to establish the association of high and low fluoride levels with intelligence level and oral health status of children aged 10-14 years in district Una, Himachal Pradesh.Methods: The study was conducted in randomly selected 15 government high schools of district Una. Study population included 600 students of government run schools in age group 10-14years. This ICMR funded project was carried out from 2014 through 2017. Dean fluorosis index was used to study fluorosis level and Intelligence test was conducted on students by using Raven’s standard progressive matrices questionnaire.Results: The 60% of sites studied for fluoride levels were found to have &gt;0.5 ppm fluoride level in water and none of them with level more than 1 ppm. Prevalence of dental fluorosis was 12.2%. Dental caries and high Dental Aesthetic Index were positively associated with high fluoride level in water. Low intelligence level of adolescents was not significantly associated with high fluoride level (OR;95% CI: 1.34; 0.72-2.49).Conclusions: This sub Himalayan region is not endemic for fluorosis however lower level of fluoride is observed in many sites. Fluorosis was not significantly associated with intelligence hence indicating towards multifactorial causation of disease.

Aplicação do software Defluoridation no dimensionamento do sistema de desfluoretação de águas subterrâneas utilizando carvão ativado de osso granulado

A ingestão de água com níveis elevados de flúor provoca uma patologia denominada fluorose dental, que resulta da mineralização defeituosa da matriz do esmalte, diretamente associada à quantidade de água ingerida de altas concentrações de fluoretos. Neste contexto, foi desenvolvido um sistema de desfluoretação por adsorção em carvão ativado de osso, seguido por precipitação por contato através da adição de sais de cálcio e fósforo. Este sistema foi construído em um tanque (filtro) de Poly Glass® com revestimento de polietileno transparente de alta densidade, preenchido com 25 kg de carvão ativado de osso de diâmetro de partícula igual a 20 x 50 mesh. Para o dimensionamento do sistema foi desenvolvido um software denominado Defluoridation, que permite a determinação das dimensões do sistema e as vazões de reagentes para o processo de precipitação por contato. O sistema foi aplicado no tratamento de água subterrânea com concentração de flúor entre 2,4 e 3,0 mg.L-1. No total, 30.000 L de água foram tratados, dos quais 13.000 L pela técnica de adsorção, e depois 7.000 L, que foram filtrados para atingir valores próximos da água bruta, e 10.000 L pela técnica de precipitação por contato. Os resultados obtidos demonstram a eficiência da aplicação do software Defluoridation, destacando que a técnica de precipitação por contato é uma forma econômica e simples para o fornecimento de água.

Morbidity and mortality resulting from acute inhalation exposures to hydrogen fluoride and carbonyl fluoride in rats

Objective: Experiments were undertaken to compare morbidity and mortality from brief inhalation exposures to high levels of hydrogen fluoride (HF) and carbonyl fluoride (COF2).Methods: Rats from both sexes were exposed for durations of 5 and 10 min to nominal concentrations of 10,000 to 57,000 ppm HF or 500 to 10,000 ppm COF2. Respiration was monitored before, during, and after exposure. Animals were observed up to 6 days post-exposure. Terminal blood samples were collected for routine clinical chemistry and hematology. Post-mortem lung fluoride concentrations and lung weights were measured, and gross pathology noted.Results: Both gases produced respiratory depression independent of concentration or exposure duration with minute ventilation decreasing to approximately 50% of baseline. Estimated mixed-gender HF and COF2 10-min LC50’s were 48,661 ppm and 1083 ppm, respectively. HF mortalities were generally delayed 3 to 4 days post-exposure, while COF2 mortalities occurred during or briefly after exposure. Lung fluoride levels increased with COF2 dose, though elevated lung weights occurred only at the mid-level exposures. Lung weights were unaffected in the HF-exposed animals, and their lung fluoride concentrations were variable. Clinical chemistry and hematology had few consistent trends with the exception of hemoconcentration primarily in HF-exposed males. These short-term exposure experiments conclude that COF2 is nearly 45 times more lethal than HF in rats.Conclusions: These experiments suggest that hydrolysis to HF cannot solely explain COF2 toxicity. Although HF and COF2 may have common injury mechanisms, they are expressed to markedly different degrees and temporal occurrence.

Preparation and Characterization of Biogenic Chitosan-Hydroxyapatite Composite: Application in Defluoridation

ABSTRACTIn Northern Tanzania, high levels of fluoride in community drinking water supply is recognized as one of the major public health concern, the problem is further ameliorated by presence Escherichia coli and fecal coliform bacteria in surface water and shallow wells. Efforts to decontaminate the water involve mostly the use of low efficient bone char for fluoride removal without disinfecting the pathogens. To address this problem, a robust adsorbent which is capable of removing fluoride and microbes simultaneously with minimal diverse impact on the treated water is necessary. Here we highlight development of composite material developed from recycling of crustacean biomass waste from sea food industry. Chitosan polymer, isolated from prawns shell was composited with crab shell derived brushite (CaHPO4.2H2O) to form chitosan-hydroxyapatite composite. XRD and FT-IR analysis confirmed transformation of brushite phases into hydroxyapatite and formation hybrid composite. Fluoride adsorption tests were performed in batch mode to evaluate effectiveness. Defluoridation capacity of up to 6.4 mg/g in field water containing fluoride concentration of 5-70 mg/L was achieved. The best performance was observed with fluoride concentration of 10 mg/L and below. Apart from fluoride removal, the composite also reduced color tint and microbes from surface water samples. The pH of the treated water in most samples remained around 6.5-8.5, which is acceptable for drinking water.

Fluoride-associated ultrastructural changes and apoptosis in human renal tubule: a pilot study.

The susceptibility of the kidneys to fluoride toxicity can largely be attributed to its anatomy and function. As the filtrate moves along the complex tubular structure of each nephron, it is concentrated in the proximal and distal tubules and collecting duct. It has been frequently observed that the children suffering from renal impairments also have some symptoms of dental and skeletal fluorosis. The findings suggest that fluoride somehow interferes with renal anatomy and physiology, which may lead to renal pathogenesis. The aim of this study was to evaluate the fluoride-associated nephrotoxicity. A total of 156 patients with childhood nephrotic syndrome were screened and it was observed that 32 of them had significantly high levels ( p ≤ 0.05) of fluoride in urine (4.01 ± 1.83 ppm) and serum (0.1 ± 0.013 ppm). On the basis of urinary fluoride concentration, patients were divided into two groups, namely group 1 (G-1) ( n = 32) containing normal urine fluoride (0.61 ± 0.17 ppm) and group 2 (G-2) ( n = 32) having high urine fluoride concentration (4.01 ± 1.83 ppm). Age-matched healthy subjects ( n = 33) having normal levels of urinary fluoride (0.56 ± 0.15 ppm) were included in the study as control (group 0 (G-0)). Kidney biopsies were taken from G-1 and G-2 only, who were subjected to ultrastructural (transmission electron microscopy) and apoptotic (terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling) analysis. Various subcellular ultrastructural changes including nuclear disintegration, chromosome condensation, cytoplasmic ground substance lysis, and endoplasmic reticulum blebbing were observed. Increased levels of apoptosis were observed in high fluoride group (G-2) compared to normal fluoride group (G-1). Various degrees of fluoride-associated damages to the architecture of tubular epithelia, such as cell swelling and lysis, cytoplasmic vacuolation, nuclear condensation, apoptosis, and necrosis, were observed.

Implementing a geographical information system to assess endemic fluoride areas in Lamphun, Thailand.

IntroductionMany studies have shown that fluoride can cross the placenta and that exposure to high fluoride during pregnancy may result in premature birth and/or a low birth weight. Lamphun is one of six provinces in Thailand where natural water fluoride (WF) concentrations >10.0 mg/L were found, and it was also found that >50% of households used water with high fluoride levels. Nevertheless, geographical information system (GIS) and maps of endemic fluoride areas are lacking. We aimed to measure the fluoride level of village water supplies to assess endemic fluoride areas and present GIS with maps in Google Maps.MethodsA cross-sectional survey was conducted from July 2016 to January 2017. Purpose sampling was used to identify villages of districts with WF >10.0 mg/L in the Mueang Lamphun, Pasang, and Ban Thi districts. Water samples were collected with the geolocation measured by Smart System Info. Fluoride was analyzed with an ion-selective electrode instrument using a total ionic strength adjustment buffer. WF >0.70 mg/L was used to identify unsafe drinking water and areas with high endemic fluoride levels. Descriptive statistics were used to describe the findings, and MS Excel was used to create the GIS database. Maps were created in Google Earth and presented in Google Maps.ResultsWe found that WF concentrations ranged between 0.10–13.60 mg/L. Forty-four percent (n=439) of samples were at unsafe levels (>0.70 mg/L), and. 54% (n=303) of villages and 46% (n=79,807) of households used the unsafe drinking water. Fifty percent (n=26) of subdistricts were classified as being endemic fluoride areas. Five subdistricts were endemic fluoride areas, and in those, there were two subdistricts in which every household used unsafe drinking water.ConclusionThese findings show the distribution of endemic fluoride areas and unsafe drinking water in Lamphun. This is useful for health policy authorities, local governments, and villagers and enables collaboration to resolve these issues. The GIS data are available at https://drive.google.com/open?id=1mi4Pvomf5xHZ1MQjK44pdp2xXFw&usp=sharing.

Fluoride in fish flesh, fish bone and regular diet in south-coastal area of Karnataka state of India.

The objective of the study was to estimate the fluoride content in regular food items available, including fish, in a coastal area of the South Karnataka state of India. Fish and food samples were collected from a local market, i.e., Deralakatte, Mangalore of Karnataka State, India. Commonly consumed different species of fish (eight types are included in the study) and popular food items (twelve types) were collected through a random sampling strategy and then processed for the study. The flesh and bones of fish were separated from individual fish. Samples of flesh, bones, and food (nonfish, vegetarian food consumed by a proportion of Karnataka population) were homogenized separately, dried, and the pH of the processed samples was adjusted to neutrality (pH 7.0). Fluoride anion was determined using a fluoride ion selective electrode (ISE, Nico2000 Ltd., UK). Although the ingredients of the different fish and food items explored differed, the same processing technique and analytical laboratory bench-work procedure were performed for each sample, i.e., as per published research elsewhere. This ensured the accurate estimation of fluoride for each food item. Concentrations of fluoride in foods (Nonfish, vegetarian food) was estimated to ranging from 0.85 to 7.09 ppm and that in fish samples ranged from 1.45 to 2.30 ppm. The highest concentration was estimated 3.16 ppm in Rohu fish flesh, and 7 ppm in rava dosa (a vegetarian food). In conclusion, the Rohu (Labeo rohita) fish species were found to contain higher concentrations of bone fluoride. Fluoride determined in fish flesh was also high in concentration 2.28 ppm. Among the regular food items, rava dosa (a thin and crispy crepe made from rava and rice flour) preparation has a higher level of fluoride. These values would provide valid information regarding the future development of recommended dietary allowance strategy for a population.

Assessment of Ground Water Quality in some villages of Lachhmangarh Tehsil-Western part, Sikar District, Rajasthan, India

Groundwater quality is an important criterion for evaluating of water. It is affected by different natural as well as anthropogenic processes. The aim of study is physico-chemical analysis of groundwater quality in some villages of eastern part of Lachhmangarh tehsil, District Sikar in pre monsoon and post monsoon season. All ground water samples were collected from Hand Pumps, Open Wells and Tube Wells and analyzed for physico chemical parameters namely Temperature, pH, Electrical Conductivity, Total Alkalinity, Total hardness, Calcium hardness, Magnesium hardness, Total Dissolved Solid, Dissolved oxygen, Fluoride, Nitrate, Carbonate, Bicarbonate, Chloride, Sulphate, Calcium, Magnesium, Sodium and Potassium. The standard methods of APHA were used to analysis of samples. The quality of groundwater has been assessed by calculating correlation coefficient (r) for every pair of parameters. The fluoride concentration in four different zones ranged from 3.5 mg/L to 7.2 mg/L. Result showed that fluoride concentration in all samples were exceeding the permissible limits prescribed by Bureau of Indian Standard (BIS) and World Health Organization (WHO). Due to the higher fluoride level in drinking water several cases of dental and skeletal fluorosis have appeared at alarming rate in this region.

Skeletal fluorosis in relation to drinking water in rural areas of West Azerbaijan, Iran

Skeletal fluorosis resulting from high fluoride level in drinking water is a major public health problem. The present study evaluated the association between exposures to drinking water fluoride and skeletal fluorosis in 5 villages of Poldasht County, Iran. All the data and information on the prevalence of bone diseases were obtained from the Health Record Department, Poldasht Health Centre. To obtain the odds ratio of bone disease problem in different risk factors, when considering the cluster effect of rural area, logistic regression in a multilevel model was used. Results showed that skeletal fluorosis of people who live in areas with high fluoride concentration is 18.1% higher than that of individuals who live in areas with low fluoride concentration. Skeletal fluorosis (54.5%) was observed in the age group of 71 years and above, and was more commonly found in females than males. According to Unadjusted, individuals who consume ≤3 unit milk and dairy products per week have almost the same level of bone diseases as compared to those that consume more than 3 units. This study indicated that, skeletal fluorosis is a general health problem in these rural areas because the results revealed that high percentage of the studied population had symptoms of skeletal fluorosis.

Characterizing the hydrogeochemistry of two low-temperature thermal systems in Central Mexico

Two low-temperature geothermal systems located at the Trans-Mexican Volcanic Belt with presence of fluoride and arsenic were studied with the aim to determine hydrogeochemical indicators of the toxic elements' presence, and to propose adequate geothermometers. The hydrogeological and geochemical study was carried out in Ixtapan de la Sal and Tonatico (IxS-T) and Santa Cruz de Juventino Rosas (JR), both located at the limits of the Trans-Mexican Volcanic Belt (TMVB). In these regions, low-temperature geothermal activity is present (T=32–47°C), and various fault and fracture systems have been identified. Several faults are active, enabling the upward flow of deep geothermal water. The geothermal waters of IxS-T manifest in the form of springs and have high Na+ and Cl− concentrations, whereas those of JR are captured in wells and mainly present high Na+ and HCO3– concentrations. The hydrochemistry of water samples was analyzed to determine the dominant hydrogeochemical processes in both regions. These data were also useful for understanding the natural origin of the high levels of arsenic and fluoride reported in the water, which are likely due to mineral dissolution processes. The concentrations of these elements surpassed the permissible limits according to Mexican law (Astot=0.025mg/L; F−=1.5mg/L) and represent a toxicity risk for the local populations. The groundwater at JR supplies all needs of the local population, while the water at IxS-T is mainly used for recreational and health spa purposes. Increasing trends of As and F− in the sedimentary aquifer of IxS-T are related with the increase in TDS, Cl−, HCO3– and SiO2, while silicate alteration releasing Na and HCO3– are related with As and F− presence in the volcanic aquifer of JR. Reservoir temperature was adequately estimated with K2/Mg and Na-K-Ca (Mg corrected) geothermometers at IxS-T, and with chalcedony and quartz geothermometers at JR.

Effects of Fluoride on Bone in an Animal Model of Vitamin D Deficiency.

We investigated the combined effect of fluoride exposure and Vitamin D deficiency in causing bone damage as a precursor to development of Fluorotoxic Metabolic Bone Disease. Thirty-six male Sprague-Dawley rats were divided into 6 groups of six; 3 groups received a Vitamin D deficient diet whereas the other 3 received a Vitamin D adequate diet. Serum total 25-hydroxyvitamin D (25OHD), calcium, phosphorus, creatinine, Alkaline phosphatase (ALP), albumin, Parathyroid hormone (PTH), Osteocalcin and C terminal telopeptide (CTx) were measured following exposure to varying levels of fluoride in drinking water (<1.0, 15 and 50ppm). Full body Dual-energy X-ray Absorptiometry (DXA) scans were used to examine changes in bone morphology pre and post exposure to fluoride. Renal tubular function was assessed using serum creatinine and urine Cystatin C. Histopathological examination of sections of bone and kidney tissues were also performed. Prior to fluoride exposure, DXA scans revealed a significant decrease in Bone Mineral Density (BMD) and Bone Mineral content (BMC) (p<0.05) but a significant increase in fat mass (p<0.05) and fat percentage (p<0.01) among Vitamin D deficient rats, with no significant change in biochemical parameters. Following exposure to fluoride, BMD was significantly increased (p<0.05) in both groups with a corresponding increase in serum ALP, bone fluoride content, Osteocalcin, CTx and urine fluoride with increasing levels of fluoride exposure. Serum creatinine calcium and phosphate and urinary cystatin C levels showed no significant changes. Light microscopy examination revealed mild thickening and increased osteoid in 80% of the Vitamin D deficient rats exposed to high levels of fluoride but renal tubular changes were found only in one experimental and one control animal. Fluoride deposited in rat bone affects both osteoblastic and osteoclastic activity. Also, these effects are accentuated in the presence of Vitamin D deficiency.

Changed expressions of N-methyl-d-aspartate receptors in the brains of rats and primary neurons exposed to high level of fluoride

Expressions of N-methyl-d-aspartic acid receptors (NMDARs) in the brains of rats and primary neurons exposed to high fluoride were investigated. Sprague-Dawley rats were divided randomly into a fluorosis group (50ppm fluoride in the drinking water for 6 months) and controls (<0.5ppm fluoride) and the offspring from these rats sacrificed on postnatal days 1, 7, 14, 21 and 28. The primary cultured neurons from the hippocampus of neonatal rats were treated with 5 and 50ppm fluoride for 48h. NMDAR subunits at protein or mRNA levels were quantified by Western blotting or real-time PCR. The phosphorylated calmodulin-protein kinase II (CaMKII) was determined by Western blotting, concentration of Ca2+ in neurons by laser confocal microscopy and apoptosis by flow cytometry. In the brains of adult rats and pups as well as in primary neurons exposed to high fluoride, the mRNAs encoding GluN1 and GluN2B subunits and the corresponding proteins were elevated, the GluN3A lowered and the GluN2A unchanged. In addition, the level of phosphor-CaMKII was reduced, and Ca2+ influx and apoptosis enhanced in the brains of rats and cultured neurons exposed to high fluoride. The results indicate that such modifications may involve brain damage induced by chronic fluorosis.

Gene-environment interaction: Does fluoride influence the reproductive hormones in male farmers modified by ERα gene polymorphisms?

The occurrence of endemic fluorosis is derived from high fluoride levels in drinking water and industrial fumes or dust. Reproductive disruption is also a major harm caused by fluoride exposure besides dental and skeletal lesions. However, few studies focus on the mechanism of fluoride exposure on male reproductive function, especially the possible interaction of fluoride exposure and gene polymorphism on male reproductive hormones. Therefore, we conducted a cross-sectional study in rural areas of Henan province in China to explore the interaction between the estrogen receptor alpha (ERα) gene and fluoride exposure on reproductive hormone levels in male farmers living in the endemic fluorosis villages. The results showed that fluoride exposure significantly increased the serum level of estradiol in the hypothalamic-pituitary-testicular (HPT) axis in male farmers. Moreover, the observations indicated that fluoride exposure and genetic markers had an interaction on serum concentration of follicle-stimulating hormone and estradiol, and the interaction among different loci of the ERα gene could impact the serum testosterone level. Findings in the present work suggest that chronic fluoride exposure in drinking water could modulate the levels of reproductive hormones in males living in endemic fluorosis areas, and the interaction between fluoride exposure and ERα polymorphisms might affect the serum levels of hormones in the HPT axis in male farmers.

ASSESSMENT OF SKELETAL FLUOROSIS AMONG CHILDREN IN TWO BLOCKS OF RURAL AREA, JAIPUR DISTRICT, RAJASTHAN, INDIA

Objective: The objective of the present study was carried out to explore the potential association between fluoride (F) concentration in drinking water and severity of skeletal fluorosis (SF) among the children of rural area.Methods: SF survey was conducted among the children (6-14 years) in two blocks such as (a) Jamwa Ramgarh block in Heerawala, Palera, Nayabas, Saipur, and Birasana and (b) Amber block in Sunder Ka Bas, Chitanukalan, Jugalpura, Peelwa, and Sirsali in Jaipur district of Rajasthan, India, of the study villages. A total of 150 (93 male and 57 female) children were surveyed. The role of fluoride (F) concentration in drinking water in the etiology of SF and the cases of SF was assessed using. The United Nations Children’s Fund three clinical test. The fluoride content in the source of drinking water was estimated by fluoride ion-specific electrode (Thermo Scientific Orion Star A329, USA).Results: The fluoride concentration in hand pump (Hp) water which ranges from 2.1 to 15 parts per million (ppm) and tube well (Tw) water ranges from 0.7 to 6.2 ppm in Jamwa Ramgarh block and Amber block, Hp water which ranges from 0.8 to 5.1 ppm and Tw water ranges from 0.8 to 4.8 ppm. The prevalence of SF 9 (12%) in Jamwa Ramgarh block and 6 (8%) in Amber block out of 75 children were examined in each block. Significantly increase in fluoride level in drinking water is positively correlated with SF.Conclusion: This study has shown the relation of SF to high fluoride levels in the source of drinking water is a major risk factor for SF among the children. SF is a threat among the children in two blocks of rural area, Jaipur district, Rajasthan.

Fluoride Depletes Acidogenic Taxa in Oral but Not Gut Microbial Communities in Mice.

Fluoridation of drinking water and dental products prevents dental caries primarily by inhibiting energy harvest in oral cariogenic bacteria (such as Streptococcus mutans and Streptococcus sanguinis), thus leading to their depletion. However, the extent to which oral and gut microbial communities are affected by host fluoride exposure has been underexplored. In this study, we modeled human fluoride exposures to municipal water and dental products by treating mice with low or high levels of fluoride over a 12-week period. We then used 16S rRNA gene amplicon and shotgun metagenomic sequencing to assess fluoride's effects on oral and gut microbiome composition and function. In both the low- and high-fluoride groups, several operational taxonomic units (OTUs) belonging to acidogenic bacterial genera (such as Parabacteroides, Bacteroides, and Bilophila) were depleted in the oral community. In addition, fluoride-associated changes in oral community composition resulted in depletion of gene families involved in central carbon metabolism and energy harvest (2-oxoglutarate ferredoxin oxidoreductase, succinate dehydrogenase, and the glyoxylate cycle). In contrast, fluoride treatment did not induce a significant shift in gut microbial community composition or function in our mouse model, possibly due to absorption in the upper gastrointestinal tract. Fluoride-associated perturbations thus appeared to have a selective effect on the composition of the oral but not gut microbial community in mice. Future studies will be necessary to understand possible implications of fluoride exposure for the human microbiome. IMPORTANCE Fluoride has been added to drinking water and dental products since the 1950s. The beneficial effects of fluoride on oral health are due to its ability to inhibit the growth of bacteria that cause dental caries. Despite widespread human consumption of fluoride, there have been only two studies of humans that considered the effect of fluoride on human-associated microbial communities, which are increasingly understood to play important roles in health and disease. Notably, neither of these studies included a true cross-sectional control lacking fluoride exposure, as study subjects continued baseline fluoride treatment in their daily dental hygiene routines. To our knowledge, this work (in mice) is the first controlled study to assess the independent effects of fluoride exposure on the oral and gut microbial communities. Investigating how fluoride interacts with host-associated microbial communities in this controlled setting represents an effort toward understanding how common environmental exposures may potentially influence health.