High Levels Of Fluoride Research Articles

Occurrence and distribution of high arsenic in sediments and groundwater of the Claromecó fluvial basin, southern Pampean plain (Argentina)

Occurrences of high arsenic (As) in sediments and groundwaters were investigated in the Claromecó fluvial basin, southern Pampean plain, Argentina. This investigation includes sedimentology, mineralogy, and hydrogeochemistry of the Neogene and Quaternary aquifers to determine possible sources and transport mechanisms for As in the Claromecó basin. Characterization of the sediments revealed homogeneous mineralogy in both Neogene highlands and Quaternary floodplains with abundant plagioclase, volcanic glass shards (VGS), K-feldspar, quartz, clay minerals and minor concentrations of clinopyroxenes, orthopyroxenes, hornblende, epidote, Fe-(oxy)hydroxides and fluorapatite. The sedimentary As concentrations ranged between 2.8 and 31 mg kg−1 in both aquifers. The average total dissolved As (dissolved AsT) concentrations was 47.2 ± 30.8 μg L−1 (15.3–110 μg L−1) in groundwater in Neogene aquifer (GW1), while it was 97.1 ± 30.6 μg L−1 (45–144 μg L−1) in Quaternary floodplain aquifer (GW2), with all samples exceeding WHO's guideline for dissolved AsT in safe drinking water of 10 μg L−1. Some GW1 (33%) and all GW2 samples contained high levels of fluoride (F−) ranging from 0.6 to 2.6 mg L−1 (1.37 ± 0.59 mg L−1) in GW1 and 2 to 5 mg L−1 (3.2 ± 0.9 mg L−1) in GW2 which also exceeded WHO's guideline for F− in safe drinking water of 1.5 mg L−1. Elevated concentrations of Na+, Cl− and SO42− in the Quaternary flood plain groundwater (GW2) could indicated some degree of sea water mixing as well as some contribution from inland processes (e.g. high evapotranspiration rates, long residence time and soil-water interactions). Dissolution of As bearing VGS or Fe-(oxy)hydroxides, alkaline desorption or competitive desorption with HCO3– from Fe-(oxy)hydroxides appear to be dominating processes of As mobilization, while desorption from fluorapatite elevate dissolved F− levels. This study provides valuable insights on As mobilization processes in Neogene and near coast Quaternary floodplain aquifer.

Utilización de un sistema de destilación solar para remoción de Arsénico y Flúor en agua subterránea destinada al consumo humano

Arsenic and fluorine occur naturally in groundwater, especially in desert and semi-desert areas. Chronic exposure through drinking water to these substances causes adverse health effect, which are limited in water intended for human consumption. Objective: This work was carried out with the aim of improving the quality of water from wells with high contents of arsenic and fluorine, achieving compliance with the limits established in the Mexican regulations for drinking water. Methodology: A system of two-panel solar distillation was used for treatment of water from three wells characterized by high levels of arsenic and fluoride, which are intended for human consumption. Contribution: The solar distillation system used improved the quality of the groundwater through the removal of arsenic (99%), fluoride (96%) and dissolved solids (98%). The proven system is a viable alternative for water treatment in small communities that do not have access to demineralization water plants that operate with high costs, thus eliminating health risks associated to the chronic intake of these elements.

Intestinal barrier damage involved in intestinal microflora changes in fluoride-induced mice

Intestinal microflora play an important role in maintaining the homeostasis of the intestinal microenvironment, but fluoride-induced changes in intestinal mechanical barrier and intestinal microflora have not been well studied. Given this paucity of information, this study aims to determine the effects of high fluoride level on intestinal mechanical barrier and intestinal microflora in the cecum of mice. Seventy-two female 21-day-old Kunming mice were randomly assigned to three groups and raised for 70 days. Changes in intestinal pathomorphology and intestinal epithelial cell proliferation were observed by haematoxylin and eosin–staining and Brdu measurement, respectively. The distribution of goblet cells, glycoproteins and mast cells was analysed through Alcian blue and periodic acid-Schiff (AB-PAS) staining, Periodic Acid-Schiff (PAS) staining, and toluidine blue staining. Results showed that excessive fluoride damaged the structure of the cecal tissues, inhibited epithelial cell proliferation and decreased the relative distribution of goblet cells, glycoproteins and mast cells that are involved in defense responses. Intestinal microflora sequencing analysis revealed that the composition of the diversity and composition of intestinal microflora was altered by excessive fluoride based on 16S rRNA amplicon sequencing. The relative abundance of Firmicutes (P = 0.03174), Bacteroidetes (P = 0.04462), Actinobacteria (P = 0.01085) and Spirochacteria (P = 0.04084) was significantly changed in the fluoride group as compared with the control group. In conclusion, excessive fluoride intake induced intestinal barrier damage, leading to changes in cecal composition, epithelium secretion and intestinal microflora.

Use of CaO Loaded Mesoporous Alumina for Defluoridation of Potable Groundwater Containing Elevated Calcium Levels

Defluoridation in the presence of high calcium levels in potable groundwater is paramount, as the consumption of groundwater enriched with fluoride, and calcium has been implicated in causing chronic kidney disease of unknown etiology (CKDu) in Sri Lanka. CaO loaded mesoporous alumina (COMA) offers a great potential for defluoridation of potable water, but the effectiveness of COMA in the presence of calcium has not been investigated. This study, therefore, focuses on the investigation of the suitability of COMA for the defluoridation of potable water with high calcium levels. Mesoporous alumina was successfully functionalized with CaO to synthesize nano-level COMA with an optimum dosage for defluoridation being 2 g L−1. The amount of fluoride adsorbed increased (2.4–19.5 mg g−1) with the increase of the initial fluoride concentration (5–40 mg L−1), and the residual fluoride levels (0.8–1.47 mg L−1) were within the range specified by the WHO for drinking water. The amount of fluoride adsorbed by COMA varied between 6.50 and 7.97 mg g−1 with initial calcium levels between 0 and 1500 mg L−1, indicating that defluoridation was effective in the presence of high calcium levels. The fluoride adsorption was best fitted with the Langmuir model with a maximum monolayer capacity of COMA being 17.83 mg g−1, and adsorption kinetics fitted with the pseudo-2nd order model indicating strong covalent bonding by way of chemisorption. Thus, COMA can be effectively utilized as an adsorbent material in defluoridation efforts in areas prevalent with CKDu in the presence of high fluoride (15 mg L−1) and calcium (1500 mg L−1) levels.

Anuran tadpoles inhabiting a fluoride-rich stream: diets and morphological indicators

We in situ assessed the influence of natural fluoride concentrations in lotic freshwater ecosystems on diet and morphology of Boana cordobae tadpoles. Two streams were sampled in Argentina: Los Vallecitos stream (LF-LV) and Los Cerros Negros stream (HF-CN) with low and high fluoride levels, respectively. We captured tadpoles of B. cordobae in each stream using nets. Body weight (BW), total length (TL) and body condition (BC) of tadpoles was registered. Food items were identified to genus level and assigned to functional traits. Tadpoles showed significant differences in TL between streams, with smaller individuals in HF-CN, while did not show differences in BW and BC. The diet of tadpoles consisted mostly of microalgae. In tadpoles from HF-CN stream the proportion of cyanobacteria was lower than tadpoles from LF-LV. In relation to functional traits, small algae, high profile and colonial algae were more abundant in HF-CN. Algae attached by pads showed a higher proportion in HF-CN diets and stalked algae were more abundant in LF-LV. The differences in TL and diet of tadpoles can be attributed to differences in algal community composition, with genera that are affected by high concentrations of natural fluoride; for example cyanobacteria. The low algal richness registered in HF-CN stream does not affect the physiological state of the tadpoles, possibly because of a higher algal density in HF-CN diets. However, in further studies it would be important to evaluate the population status of B. cordobae from the HF-CN, because a small body length of tadpoles could have consequences at the population level.

Fluoride Concentration in Groundwater of Khapa Town, Saoner Tehsil, Nagpur District – A Case Study

Fluoride is known to contaminate groundwater in many countries notably India, Sri Lanka, China, rift valley countries in East Africa, Turkey and parts of South Africa. Sporadic incidence of high fluoride content in groundwater has been reported in 19 states and union territories across the country (CGWB 2010; Pol 2012). The fluoride occurrences in top aquifer system are endemic in many parts of Andhra Pradesh, Tamil Nadu, Karnataka, Gujarat, Rajasthan, Punjab, Haryana, Bihar and Kerala (Agarwal et al. 1997; Latha et al. (1999); Gopalakrishnan et al. (2012). The toxicity of fluoride is generally influenced by high ambient temperature, alkalinity, calcium and magnesium contents in drinking water (BIS 1991). High level of fluoride posses serious health hazards to humans and irreversible damage to plants. The present study was carried out to assess the fluoride concentration of groundwater in the selected villages around Khapa town of Nagpur district.

Exposure to fluoride aggravates the impairment in learning and memory and neuropathological lesions in mice carrying the APP/PS1 double-transgenic mutation

BackgroundAlzheimer’s disease (AD) is responsible for 60–70% of all cases of dementia. On the other hand, the tap water consumed by hundreds of millions of people has been fluoridated to prevent tooth decay. However, little is known about the influence of fluoride on the expression of APP and subsequent changes in learning and memory and neuropathological injury. Our aim here was to determine whether exposure to fluoride aggravates the neuropathological lesions in mice carrying the amyloid precursor protein (APP)/presenilin1 (PS1) double mutation.MethodsThese transgenic or wide-type (WT) mice received 0.3 ml of a solution of fluoride (0.1 or 1 mg/ml, prepared with NaF) by intragastric administration once each day for 12 weeks. The learning and memory of these animals were assessed with the Morris water maze test. Senile plaques, ionized calcium binding adaptor molecule 1 (Iba-1), and complement component 3 (C3) expression were semi-quantified by immunohistochemical staining; the level of Aβ42 was detected by Aβ42 enzyme-linked immunosorbent assays (ELISAs); the levels of synaptic proteins and enzymes that cleave APP determined by Western blotting; and the malondialdehyde (MDA) content and activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) measured by biochemical procedures.ResultsThe untreated APP mice exhibited a decline in learning and memory after 12 weeks of fluoride treatment, whereas treatment of these some animals with low or high levels of fluoride led to such declines after only 4 or 8 weeks, respectively. Exposure of APP mice to fluoride elevated the number of senile plaques and level of Aβ42, Iba-1, and BACE1, while reducing the level of ADAM10 in their brains. The lower levels of synaptic proteins and enhanced oxidative stress detected in the hippocampus of APP mice were aggravated to fluoride.ConclusionsThese findings indicate that exposure to fluoride, even at lower concentration, can aggravate the deficit in learning and memory and neuropathological lesions of the mice that express the high level of APP.

Morphological abnormalities in natural populations of the common South American toad Rhinella arenarum inhabiting fluoride-rich environments

Morphological abnormalities in amphibians may be attributed to contaminants, ultraviolet radiation and trematode parasites, or a synergistic effect between them. In the present study, morphological abnormalities in Rhinella arenarum adults from natural and artificial fluoride-rich environments were identified and evaluated. Three sites were sampled in central Argentina: Los Vallecitos stream (LF-LV), Los Cerros Negros stream (MF-CN), and Decantation ponds (HF-DP), with low (0.33 mg/L), middle (2.03 mg/L) and high (14.0 mg/L) fluoride levels respectively; the latter site is associated with a fluoride mine. Abnormal individuals were photographed and then standard radiographs were taken. Abnormality frequencies and relative percentage of abnormal individuals were calculated for each site. In addition, skeletochronology was used to estimate toad's age. Five abnormality types were identified: syndactyly, ectrodactyly, polydactyly, microphthalmia and ectromelia. Percentages of abnormal individuals per site were: LF-LV = 4%, MF-CN = 21.2% and HF-DP = 6.4%. The MF-CN and HF-DP populations had morphological abnormality frequencies that exceeded the reference value (5%) reported in the literature. The average age did not differ between sites. The results of this study indicate that there is an association between frequency of morphological abnormalities and high fluoride levels.

Geospatial Analysis of Fluoride Concentration in Groundwater in Puruliya District, West Bengal

Fluoride contamination in groundwater is a major geo-environmental issue. In India, groundwater sources contribute more than 85 per cent of the drinking water requirement in rural areas, 76 per cent of irrigation requirements and more than 50 per cent of the urban and industrial water supplies. Many studies have reported fluoride-related health problems such as dental and skeletal fluorosis in humans due to drinking of fluoride-rich water which has severe socio-economic implications. The permissible limit of fluoride in drinking water is 1.5 mg/l according to the World Health Organisation (WHO, 2004) and the Bureau of Indian Standards (BIS, 2012). Puruliya is the westernmost district of West Bengal and located on the eastern slope of the Chotanagpur plateau. The intensive and prolonged dry spell, semi-arid climate, long-term withdrawal of groundwater for irrigation, alkaline nature of sub-surface circulating water, a long residence time of water in fractured aquifers and low chances of dilution are favourable for fluoride enrichment in the Puruliya District. Eighteen out of 20 blocks of the district have high fluoride level in groundwater. This paper attempts to examine the status of fluoride concentration in groundwater, its distribution including the causative factors for its occurrence. It also tries to draw a comparative view of the change in fluoride pattern for the period 2005-06 and 2015-16 and estimate population under threat. Data collected from Physical Health & Engineering Department (PHED) is superimposed over topographical maps and Google Earth. Mapping of fluoride endemic areas in Puruliya district is attempted to delineate areas and the extent of fluoride contamination in the study area.

Fluoride distribution in underground water of district Mahendergarh, Haryana, India

High fluoride concentration in groundwater occurs in majority of the dry and semidry regions of the Indian subcontinent. Mahendergarh district of Haryana state has been identified as Red Alert zone of high fluoride by Geological Survey of India (GSI). Most of the residents of Mahendergarh district are using ground water for drinking and irrigational purposes. The main purpose of the present study was to analyze the level of fluoride in ground water in all the eight blocks, i.e., Satnali, Sihma, Narnaul, Mahendergarh, Nizampur, Ateli, Kanina and Nangal Chaudhary of Mahendergarh district. Water samples were collected from 355 villages of the study area during December 2016 to May–June 2017 and were analyzed to find out the fluoride concentration with ion-selective electrode method. The fluoride distribution in Mahendergarh district ranged from 0.3 to 16.0 mg/l in ground water samples. Lowest value of 0.3 mg/l was reported in Dalanwas village of Satnali block and highest value of 16.0 mg/l in Narnaul city of Narnaul block. The outcome of the study revealed that out of 355 villages of the district, the fluoride level in 205 villages was found within the upper acceptable limit prescribed by WHO, i.e., 1.5 mg/l. The fluoride concentration in 150 villages was above permissible limit that may cause fluorosis among residents of the district. The fluoride distribution pattern showed that the high fluoride level was observed in the central part and the lowest in northwest part of the study area.

Comparison of different iron oxide adsorbents for combined arsenic, vanadium and fluoride removal from drinking water

Contamination of groundwater by arsenic due to natural processes is rather common worldwide and hinders its use for drinking water supply. In many cases, arsenic contamination is found together with high levels of vanadium and fluoride. Therefore, more than one type of treatment is required to reduce concentrations of all these contaminants below non-hazardous levels so to make the source drinkable. The present study investigated the uptake capacity of arsenic, vanadium and fluoride by three iron-based adsorbent media differing for particle size, iron content and specific surface. The aim of the treatment was to achieve the maximum allowable concentration set on drinking water by the law. The removal efficiency was evaluated in single and binary contaminated solutions. All the tested adsorbents demonstrated an efficient and rapid removal process of both arsenic and vanadium in the single and binary solutions, with a higher adsorption capacity for vanadium; by contrast, they were unable to achieve an appreciable reduction in fluoride concentration. The particle size showed to have the highest effect on the removal rate. The best kinetic and isotherm models and the related parameters were determined for each condition. In the binary solutions, the presence of vanadium hindered the uptake of arsenic, whereas fluoride did not have any effect. The results obtained showed that the iron-based adsorbents tested in the present study can be successfully applied for the treatment of drinking water contaminated by arsenic and vanadium, whereas a different medium or process needs to be adopted for the removal of fluoride.

White Teeth and Healthy Skeletons for All: The Path to Universal Fluoride-Free Drinking Water in Tanzania

Fluorosis has been prevalent in the great East African Rift Valley (EARV) since before this region was given a name. In the Tanganyika days, Germans reported elevated fluoride concentrations in natural waters. In the 1930s, the clear relationship between high fluoride level and mottling of teeth was established. Since then, the global research community has engaged in the battle to provide fluoride-free drinking water, and the battle is not yet won for low-income communities. An applicable concept for fluoride-free drinking water in the EARV was recently presented, using the Kilimanjaro as a rainwater harvesting park. The Kilimanjaro concept implies that rainwater is harvested, stored on the Kilimanjaro mountains, gravity-transported to the point of use, eventually blended with natural water and treated for distribution. This article provides a roadmap for the implementation of the Kilimanjaro concept in Tanzania. Specifically, the current paper addresses the following: (i) presents updated nationwide information on fluoride contaminated areas, (ii) discusses the quality and quantity of rainwater, and current rainwater harvesting practices in Tanzania, (iii) highlights how low-cost water filters based on Fe0/biochar can be integrating into rainwater harvesting (RWH) systems to provide clean drinking water, and (iv) discusses the need for strict regulation of RWH practices to optimize water collection and storage, while simplifying the water treatment chain, and recommends strict analytical monitoring of water quality and public education to sustain public health in the EARV. In summary, it is demonstrated that, by combining rainwater harvesting and low-cots water treatment methods, the Kilimanjaro concept has the potential to provide clean drinking water, and overcome fluorosis on a long-term basis. However, a detailed design process is required to determine: (i) institutional roles, and community contributions and participation, (ii) optimal location and sizing of conveyance and storage facilities to avoid excessive pumping costs, and (iii) project funding mechanisms, including prospects for government subsidy. By drawing attention to the Kilimanjaro concept, the article calls for African engineers and scientists to take the lead in translating this concept into reality for the benefit of public health, while simultaneously increasing their self-confidence to address other developmental challenges pervasive in Africa.

Dental fluorosis and oral health in the African Esophageal Cancer Corridor: Findings from the Kenya ESCCAPE case-control study and a pan-African perspective.

There are no studies of oral health in relation to esophageal cancer in Africa, or of Eastern Africa's endemic dental fluorosis, an irreversible enamel hypo‐mineralization due to early‐life excessive fluoride intake. During 2014–18, we conducted a case–control study of squamous cell esophageal cancer in Eldoret, western Kenya. Odds ratios (AORs (95% confidence intervals)) were adjusted for design factors, tobacco, alcohol, ethnicity, education, oral hygiene and missing/decayed teeth. Esophageal cancer cases (N = 430) had poorer oral health and hygiene than controls (N = 440). Compared to no dental fluorosis, moderate/severe fluorosis, which affected 44% of cases, had a crude OR of 20.8 (11.6, 37.4) and on full adjustment was associated with 9.4‐fold (4.6, 19.1) increased risk, whilst mild fluorosis (43% of cases) had an AOR of 2.3 (1.3, 4.0). The prevalence of oral leukoplakia and tooth loss/decay increased with fluorosis severity, and increased cancer risks associated with moderate/severe fluorosis were particularly strong in individuals with more tooth loss/decay. Using a mswaki stick (AOR = 1.7 (1.0, 2.9)) rather than a commercial tooth brush and infrequent tooth brushing also independently increased risk. Geographic variations showed that areas of high esophageal cancer incidence and those of high groundwater fluoride levels have remarkably similar locations across Eastern Africa. In conclusion, poor oral health in combination with, or as a result of, high‐altitude susceptibility to hydro‐geologically influenced dental fluorosis may underlie the striking co‐location of Africa's esophageal cancer corridor with the Rift Valley. The findings call for heightened research into primary prevention opportunities of this highly fatal but common cancer.

Health impact of supplying safe drinking water on patients having various clinical manifestations of fluorosis in an endemic village of west bengal.

Background:Excessive fluoride in drinking water causes dental, skeletal and non-skeletal fluorosis which is encountered in endemic proportions in several parts of the world. The World Health Organization (WHO) guideline value and the permissible limit of fluoride as per the Bureau of Indian Standards (BIS) is 1.5 mg/L. Studies showed that withdrawal of sources identified for fluoride, often leads to reduction of fluoride in the body fluids (re-testing urine and serum after a week or ten days) and results in the disappearance of non-skeletal fluorosis within a short duration of 10-15 days.Objective:To determine the prevalence of signs and symptoms of suspected dental, skeletal and non-skeletal fluorosis along with food habits, addictions and use of fluoride-containing toothpaste among participants taking water with fluoride concentration above permissible limit and to assess the changes in clinical manifestations of the above participants after consumption of safe drinking water with fluoride concentration below permissible limit.Materials and Methods:A longitudinal intervention study was conducted from October 2010 to December 2011 in a village selected randomly in Purulia District of West Bengal which is endemic for fluorosis. Thirty-six families with 104 family members in the above village having history of taking unsafe water containing high level of fluoride were selected for the study. The occurrence of various dental, skeletal and non-skeletal manifestations of fluorosis along with food habits, addictions and use of fluoride-containing toothpaste among the study population was assessed; the impact of taking safe water with fluoride concentration below permissible limit from a supplied community filter on these clinical manifestations was studied by follow-up examination of the above participants for six months. The data obtained is compared with the collected data from the baseline survey.Results:The prevalence of signs and symptoms of dental, skeletal and non-skeletal fluorosis was (18.26%), (18.26-43.26%) and (12.49-38.46%) among the study population. Withdrawal of source(s) identified for fluoride by providing community filters supplying safe water along with nutritional interventions lead to 1.92% decrease of manifestation of dental fluorosis, 2.88-18.26% decrease of manifestations of skeletal fluorosis and 3.8-5.77% decrease in manifestations of non-skeletal fluorosis within six months. Following repeated motivation of participants during visit there was also 2.88% decrease in the usage of fluoride-containing toothpaste, 4.81% decrease in consumption of black lemon tea, supari and tobacco which are known sources of fluoride ingestion in our body.Conclusion:Increased prevalence of dental, skeletal and non-skeletal fluorosis was found among the study population. Withdrawal of sources(s) identified for fluoride by supplying community filter, dietary restriction and other nutritional interventions led to decrease of manifestations of the three types of fluorosis within six months. The government should play a vital role in ensuring drinking water safety at the household and community level by supplying domestic filters at affordable costs and community filter along with nutritional intervention to the fluorosis-affected villages on a priority basis to mitigate the problem.

A mini review of fluoride-induced apoptotic pathways

Fluorine or fluoride can have toxic effects on bone tissue and soft tissue at high concentrations. These negative effects include but not limited to cytotoxicity, immunotoxicity, blood toxicity, and oxidative damage. Apoptosis plays an important role in fluoride-induced toxicity of kidney, liver, spleen, thymus, bursa of Fabricius, cecal tonsil, and cultured cells. Here, apoptosis activated by high level of fluoride has been systematically reviewed, focusing on three pathways: mitochondrion-mediated, endoplasmic reticulum (ER) stress-mediated, and death receptor-mediated pathways. However, very limited reports are focused on the death receptor-mediated apoptosis pathways in the fluoride-induced apoptosis. Therefore, understanding and discovery of more pathways and molecular mechanisms of fluoride-induced apoptosis may contribute to designing measures for preventing fluoride toxicity.

Hydrogeochemistry and groundwater quality assessment of high fluoride levels in the Yanchi endorheic region, northwest China

Groundwater is the primary source of water for irrigation and domestic purposes in the Yanchi endorheic region, an arid area in northwest China. A comprehensive understanding of the hydrogeochemical characteristics and groundwater quality is indispensable for the sustainable utilization of the groundwater sources. For this reason, twenty-seven groundwater samples were collected in three seasons. A hydrogeochemical assessment and entropy-weighted water quality index (EWQI) were used to investigate the sources of high sodium, sulfate and fluoride concentrations, to evaluate the groundwater quality and to ascertain the factors controlling the groundwater quality, the spatial distribution and the seasonal variation. The dissolution of halite and gypsum supplies most of the Na+ and SO42−, respectively, in the groundwater, and cation exchange further enhances the Na+ content. The main sources of the high F− concentrations are the dissolution of fluorite and desorption of exchangeable F−. This groundwater environment, which is Na-rich and Ca-poor, has high pH values, and the precipitation of calcite and dolomite provides favorable conditions for the enrichment of fluoride. In the three sampling seasons, 48%, 52% and 48% of the groundwater was categorized as poor- or extremely poor-quality water, which is not suitable for drinking purposes, according to the self-defined classifications of EWQI. The high EWQI values are mainly observed in the mountain front and discharge area of the groundwater runoff. The high concentrations of Na+, SO42−, F−, and TDS are the greatest contributing parameters to the low groundwater quality, and the assessed impacts decrease in the following order: Na+ > TDS > SO42− > F−. The spatial distribution of the EWQI versus four hydrochemical parameters reveals that the groundwater quality improves but the influential factors do not change with the seasonal variation.

Dopamine receptor D2 gene polymorphism, urine fluoride, and intelligence impairment of children in China: A school-based cross-sectional study

ObjectiveWe aimed to study the association of urine fluoride with intelligence quotient (IQ) in children with a careful consideration of up to 30 potential confounding factors as well as possible heterogeneity of the relation between urine fluoride levels and IQ scores across children with different dopamine receptor-2 (DRD2) Taq 1A genotypes (CC, CT, and TT). MethodsA school-based cross-sectional study design was applied. A total of 323 children (2014–2015, 7–12 years old) were enrolled from four schools in both historical endemic and non-endemic areas of fluorosis in Tianjin of China using a cluster sampling method. Urine fluoride levels and age-specific IQ scores in children were measured at the enrollment. Polymerase chain reaction-restriction fragment length polymorphism methods were used to genotype DRD2 Taq 1A polymorphism with genomic DNA isolated from whole blood collected at the enrollment. Multiple linear regression models were applied to evaluate the relationship between urine fluoride levels and IQ scores overall and within the DRD2 Taq 1A SNP = CC/CT and TT subgroups. Model robustness was tested through bootstrap, sensitivity analysis, and cross-validation techniques. A safety threshold of urine fluoride levels for IQ impairment was determined in the subgroup TT. ResultsIn overall participants, the DRD2 Taq 1A polymorphism itself was not related to IQ scores in children who had a high level of urine fluoride. In the CC/CT subgroup, urine fluoride levels and IQ scores in children were unrelated (adjusted β (95% confidence interval (CI)) = − 1.59 (− 4.24, 1.05), p = 0.236). Among the participants carrying the TT genotype, there was a strong and robust negative linear relationship between log-urine fluoride and IQ scores in children (adjusted β (95% CI) = − 12.31 (− 18.69, − 5.94), p < 0.001). Urine fluoride levels had a stronger association with IQ in children carrying the TT genotype (adjusted β = − 12.31, bootstrapped standard error (SE) = 1.28), compared to that in overall participants (adjusted β = − 2.47, bootstrapped SE = 3.75) (Z = 2.483 and bootstrapped p = 0.007). The safety threshold of urine fluoride levels in the subgroup TT was 1.73 mg/L (95% CI = (1.51, 1.97) (mg/L)). ConclusionsThere is heterogeneity in the relation between urine fluoride and IQ across children carrying different DRD2 Taq 1A genotypes. Large-scale epidemiological studies are needed to confirm our findings.

Occurrence of fluorosis in a population living in a high-fluoride groundwater area: Nakuru area in the Central Kenyan Rift Valley.

Endemic fluorosis caused by the consumption of high-fluoride groundwater is a public health problem in Nakuru, in the Kenyan Rift Valley. The present study was carried out during the period January-February 2017 to determine the prevalence and severity of dental fluorosis among patients of two Nakuru healthcare facilities, namely St. Mary's Hospital-Gilgil and Egerton University-Njoro Dental Clinic. The patients consisted of both young and old members of the Nakuru population served with groundwater containing high levels of fluoride ranging from 0.1 to 72mg/l. The Thylstrup-Fejerskov (TF) index was used to estimate the severity of dental fluorosis. Among the patients of St. Mary's Hospital-Gilgil, the prevalence of dental fluorosis was 86% (n = 100), whereby 54% of the patients were found to have mild to moderate dental fluorosis and 32% had severe dental fluorosis. Whereas the prevalence of dental fluorosis in patients below the age of 14years was higher (92%) than in older patients (85.56%), severity was reversed (average TF = 3.77 for older patients; average TF = 2.18 for younger patients). No significant variation in severity and prevalence of dental fluorosis was recorded with respect to both genders of the patients. The dental fluorosis prevalence rate amongst the patients of the Egerton University-Njoro Dental Clinic was found to be 79.49% (n = 73). However, a comparative analysis of the two age groups revealed a much higher prevalence rate of 100% for patients below the age of 14 relative to the older patients (79.49%). While a high number of cases of dental fluorosis from both healthcare facilities were reported in patients residing in Njoro, Nakuru town, Gilgil and Bahati, the fewer cases were from Solai and Rongai. The results seem to suggest a much higher occurrence of dental fluorosis within the younger population group. This implies that rapid population growth and urbanization puts more pressure on public water resources which leads to a strong reliance on fluoride contaminated groundwater and the concomitant increased cases of dental fluorosis. Therefore, there is a need for a change of local government policy to enhance access to safe water and public education on fluorosis in the areas that were under investigation.

Investigating the chemistry of alumina based defluoridation using safe H+ source

The existence of high levels of fluoride in drinking water is a worldwide problem and activated alumina is an established adsorbent for fluoride removal. This article investigates factors governing rate of fluoride uptake, mechanical stirring as well as interference from competing ions, of the defluoridation employing activated alumina. Pre-treatment with aqueous solution of sulphuric acid has shown faster uptake in a small setup was demonstrated recently. An attempt to understand the phenomena by profiling ionic species on the active surface of activated alumina, native and acid treated. Presence of carbonate species was found, in Raman spectra, on native surface which can explain effectiveness of pre-treatment. Broadening of hydroxyl species profiles, in infrared and solid-state NMR spectra, suggests incorporation of water into new sites. Fluoride treatment of the pre-treated activated alumina leads to narrowing of hydroxyl species profiles suggesting incorporation of fluoride into new sites. A mechanism is being proposed wherein H+ ions in the presence of SO42- (from KHSO4 or NaHSO4) enables the energetics for faster defluoridation and regeneration of activated alumina.

Potential Co-exposure to Arsenic and Fluoride and Biomonitoring Equivalents for Mexican Children.

Background:Mexico is included in the list of countries with concurrent arsenic and fluoride contamination in drinking water. Most of the studies have been carried out in the adult population and very few in the child population. Urinary arsenic and urinary fluoride levels have been accepted as good biomarkers of exposure dose. The Biomonitoring Equivalents (BE) values are useful tools for health assessment using human biomonitoring data in relation to the exposure guidance values, but BE information for children is limited.Methods:We conducted a systematic review of the reported levels of arsenic and fluoride in drinking water, urinary quantification of speciated arsenic (inorganic arsenic and its methylated metabolites), and urinary fluoride levels in child populations. For BE values, urinary arsenic and fluoride concentrations reported in Mexican child populations were revised discussing the influence of factors such as diet, use of dental products, sex, and metabolism.Results:Approximately 0.5 and 6 million Mexican children up to 14 years of age drink water with arsenic levels over 10 µg/L and fluoride over 1.5 mg/L, respectively. Moreover, 40% of localities with arsenic levels higher than 10 µg/L also present concurrent fluoride exposure higher than 1.5 mgF/L. BE values based in urinary arsenic of 15 µg/L and urinary fluoride of 1.2 mg/L for the environmentally exposed child population are suggested.Conclusions:An actual risk map of Mexican children exposed to high levels of arsenic, fluoride, and both arsenic and fluoride in drinking water was generated. Mexican normativity for maximum contaminant level for arsenic and fluoride in drinking water should be adjusted and enforced to preserve health. BE should be used in child populations to investigate exposure.