Health risk from fluoride exposure of a population in selected areas of Tamil Nadu South India

Soft Drinks as a Dietary Source of Fluoride Exposure

High fluoride exposures can lead to adverse effects such as dental and bone fluorosis, as well as endocrine and cognitive developmental problems. Water is the main dietary source of this ion, although significant concentrations have also been detected in other beverages widely consumed by the population such as soft drinks. A total of 200 soft drink samples (60 flavoured, 70 extracts, 60 fruit juice and 10 soft drinks) were analysed by fluoride ion selective potentiometry. A consumption of 330 mL was estimated for exposure assessment and subsequent F-risk assessment by soft drink consumption. The highest average concentration was found in extract soft drinks (2.45 ± 1.15 mg/L), followed by flavoured (1.71 ± 2.29 mg/L) and carbonated soft drinks (1.38 ± 0.40 mg/L), while the lowest was found in fruit juice soft drinks (1.09 ± 0.62 mg/L). The flavours with the highest concentration were tea-melon and tea-passion fruit with 3.66 ± 0.40 and 3.17 ± 0.56 mg/L respectively and the lowest was lemon flavour with 0.69 mg/L. The contribution of these beverages, considering the UL (Upper level) reference values set by EFSA (European Food Safety Authority) are between 3.28-41.78%, depending on age group and sex.

Health risk assessment of fluoride exposure due to groundwater consumption in Romania

Fluoride has both beneficial and detrimental effects on human health. Concentrations of fluoride less than 1.0 mg/L in ingested water are beneficial for the rate of tooth decay, especially in children. The aims of the paper are as follows: (i) to monitor fluoride concentrations in drinking water samples (well water and tap water from the rural district of Valea Râmnicului, Romania); (ii) to study and select the optimal buffer solution and the optimal volume used in the analyses and (iii) to validate the potentiometric method for determining fluoride ions with a selective ion electrode. The values of fluoride ion concentrations in the groundwater samples and in tap water varied from 0.01 to 0.138 mg^/L. The values for the hazard quotient for the studied samples varied from 0.01 to 0.13.

Mesoporous aluminum impregnated rubber seed shell waste enriched with calcium as adsorbent material for the removal of microbial DNA in aqueous solution

Water contamination by pathogens and diseases induced by these pathogens is a major water quality issue all over the world. Poor public health has been linked to tap water polluted with DNA harboring antibiotic resistance genes sequence. According to HSAB concept, surface modification of rubber seed shell waste with alumina (AIRSS) as novel agro-waste adsorbent creates more active surface constituents for DNA adsorption. The proximate, ultimate and EDAX analysis provides the percentage levels of ash concentration, volatile, moisture and fixed carbon content, elemental composition present in the adsorbent. The structural features of AIRSS were determined using FT-IR, SEM and XRD. In order to improve reaction conditions, the effect of pH, temperature, adsorbent amount, and reaction time is also examined. The highest percent of DNA removal (92.5%) was achieved at the optimum conditions: 2 g/L at pH 4, contact time 120 minutes as compared to the conventional methods. The DNA adsorbs onto the surface of AIRSS through physical (vander Waals force) and chemical interactions, as demonstrated by kinetics and spectroscopic analyses. Changes in enthalpy (H), free energy (G), and entropy (S) indicate that adsorption is a spontaneous and exothermic process, according to thermodynamic parameters. The results of the experiments showed that the prepared AIRSP adsorbent could be used to remove DNA from water. The efficacy of AIRSS for the removal of DNA has decreased after nine months of storage and use. Low pH and the presence of AIRSS improved DNA-AIRSS adsorption, according to our findings.

Enhanced biosorption of fluoride by extracted nanocellulose/polyvinyl alcohol composite in batch and fixed-bed system: ANN analysis and numerical modeling

The present investigation attempted to examine the defluoridation feasibility onto the extracted nanocellulose/PVA polymer composites. Nanocellulose were derived from sugarcane bagasse and blended with PVA (polyvinyl alcohol) polymer matrix. The defluoridation potential of nanocellulose/PVA was observed to be significantly dependent on the various operational factors including pH, time interval, etc. the Temkin isotherm (R² = 0.989) as well as the Langmuir isotherm equation (R² = 0.982) could well fit with the investigational data. Following the Langmuir isotherm, the maximum monolayer adsorption capacity for fluoride elimination at 25°C was obtained as 11.363 mg g^-1. The nature of rate-limiting steps involved in defluoridation process might be effectively predicted by pseudo-second-order kinetics. Values of thermodynamic state properties achieved as of the thermodynamic analysis showed that the defluoridation process was spontaneous, exothermic, and feasible. The diffusion and mass transfer study were estimated by following the Boyd's model. Average effective diffusion coefficient (D_e) at various initial fluoride concentrations (4-10 mg L^-1) was obtained as 15.3343×10^-7 m²s^-1 and the estimated magnitude of the mass-transfer coefficient (K_f) was 0.0346×10^-9 m s^-1 (temperature = 298 K, C₀= 6 mgL^-1). An ANN (artificial neural network) model applied to optimize and simulate the defluoridation procedure. Furthermore, continuous flow column reactor was conducted to investigate the practical applicability of composites in the defluoridation process. The Yoon-Nelson and the Thomas model exhibited excellent conformity with the breakthrough curves. Nanocellulose/PVA satisfactorily eliminated fluoride from its aqueous solution and can be considered as a suitable bio-sorbent for defluoridation.

Spatial Assessment of Groundwater Quality and Health Risk of Nitrogen Pollution for Shallow Groundwater Aquifer around Fuyang City, China

Prolonged exposure to intensive and extensive agricultural and industrial activities is leading to an increased deterioration of groundwater quality, especially nitrogen pollution in shallow groundwater aquifers. This study was carried out using the fuzzy comprehensive method to assess the overall groundwater quality, and the noncarcinogenic risks were estimated using the human health risk assessment method recommended by the United States Environmental Protection Agency (USEPA) via drinking water intake pathways around Fuyang City, China. A total of 34 samples were collected from shallow groundwater private wells, and 16 parameters were analyzed for each groundwater sample. The evaluation results of groundwater quality show 14.7% of groundwater samples classified as poor and very poor quality, and NO3-N, TH, TDS, Fe3+, and Mn are of high potential to affect the quality of potable drinking water. These are mainly derived from anthropogenic pollutants, predominantly due to uncontrolled agricultural and industrial activities, as well as some natural processes. The noncarcinogenic risk of nitrate indicates that 8.82% of groundwater samples surpass the permissible limit recommended by the USEPA for both adults and children. This study may provide the local authority with insights into making scientific decisions for exploiting groundwater in a sustainable manner so as to protect public health.

Co-occurrence, possible origin, and health-risk assessment of arsenic and fluoride in drinking water sources in Mexico: Geographical data visualization

Arsenic and fluoride in drinking water present a significant challenge to public health worldwide. In this study, we analyze the results of one of the largest surveys of drinking water quality in Mexico: 14,058 samples from 3951 sites, collected between January and December 2017. We use these data to identify the distribution and possible origin of arsenic and fluoride in drinking water throughout the country, and to estimate the associated health burden. The highest concentrations appear in alluvial aquifers in arid northern Mexico, where high-silica volcanic rock likely releases both arsenic and fluoride to the groundwater. We find fluoride contamination to be significantly correlated with aridity (Pearson correlation = -0.45, p = 0.0105), and also find a significant difference in fluoride concentrations between arid and humid states (Welch's t-test, p = 0.004). We estimate population exposure by assigning to each town in Mexico the average concentration of any sampling sites within 5 km. Our results show that 56% of the Mexican population lives within 5 km of a sampling site, 3.05 million people are exposed to fluoride above the reference dosage of 0.06 mg/(kg ∗ day), 8.81 million people are exposed to arsenic above the limit of 10 μg/L, and an additional 13,070 lifetime cases of cancer are expected from this arsenic exposure alone. This burden of disease is concentrated in the arid states of north-central Mexico.

Fluoride contamination in groundwater and associated health risks in Karbi Anglong District, Assam, Northeast India

Health hazards due to excess intake of fluoride via groundwater contamination are a major concern worldwide. This study provides a comprehensive report on the human health risks associated with the consumption of groundwater contaminated by fluoride. Several groundwater samples were collected across 8 blocks of Karbi Anglong district of Assam, India. The concentration of fluoride was observed in the range of 0.15-17.13 mg/L. In 4 out of 8 studied blocks, the mean fluoride level exceeded the permissible limit (1.5 mg/L) as prescribed by the World Health Organization. Elevated fluoride levels in some parts of the district may be attributed mainly to dissolution from fluoride-containing minerals in the granitic rocks and regional geological settings. The health risk of fluoride was assessed in terms of hazard quotient (HQ). The HQ was observed in the ranges of 0.06-10.7 (adult) and 0.2-35 (children). Mean HQ values exceeded the safe level (HQ > 1) for children in all blocks, except B-6 and B-8. For adult population, the HQ value was above the safe limits in 13-40% of the sampled locations in different blocks and HQ values were within safe limits in B-6 and B-8. These findings suggest that some sites in the district need serious attention in order to ensure the health safety of local residents.

Assessment of fluoride intake from groundwater and intake reduction from delivering bottled water in Chiang Mai Province, Thailand

Fluoride intake from tap water supplied by fluoride-containing groundwater has been the primary cause of fluorosis among the residents of Buak Khang Subdistrict, Chiang Mai Province, Thailand. To reduce fluoride intake, bottled water treated using reverse-osmosis membranes has been made available by community-owned water treatment plants. This study aimed to assess the resultant reduction in fluoride intake from using bottled water for drinking and cooking. Water consumption surveys were conducted by providing bottled water to 183 individuals from 35 randomly selected households and recording the amount of water consumed for drinking and cooking. The mean drinking water consumption was 1.62-1.88 L/capita/day and the cooking water consumption on weekends (5.06 ± 3.04 L/household/day) was higher than that on weekdays (3.80 ± 1.90 L/household/day). The per capita drinking water consumption exhibited a positive correlation with body weight; however, the low-weight subjects consumed more drinking water per kilogram of body weight than the heavy subjects. Although sex and day of the week did not significantly affect drinking water consumption per capita, girls consumed less water in school possibly due to their group mentality. Drinking water consumption per kilogram of body weight was significantly higher among women, children, and the elderly because these groups generally have low body weights. The fluoride intake from using tap water for drinking and cooking was estimated to be 0.18 ± 0.10 mg/kg-body weight/day and 5.55 ± 3.52 mg/capita/day, respectively, whereas using bottled water for drinking and cooking reduced the fluoride intake to 0.002 ± 0.002 mg/kg-body weight/day and 0.07 ± 0.05 mg/capita/day, respectively. Despite the increased cost, 98% and 90% of the subjects selected bottled water over tap water for drinking and cooking, respectively; thus, bottled water delivery services could be used to mitigate fluoride intake in developing countries.

Calix[4]arene urea derivatives: The pathway from fundamental studies to the selective removal of fluorides and phosphates from water

Wet processes of phosphoric acids produce untreated wastewater containing large amounts of fluoride leading to serious environmental problems. This paper reports fundamental studies on two lower rim functionalised calix[4]arene based receptors namely 5, 11, 17, 23 tetra-tert-butyl, 25, 27 bis [diethylphenylurea]ethoxy, 26, 28 dihydroxycalix[4]arene, 1 and 25, 27 bis[diethylphenylurea]ethoxy, 26, 28 dihydroxycalix[4]arene, 2 and their ionic interactions. It is shown that these receptors only interact with fluoride and phosphate in acetonitrile. Their receptive properties are higher for phosphate (2:1 anion:receptor complex) relative to fluoride (1:1 complex). However, thermodynamics shows that these receptors are more selective for fluoride relative to phosphate in the formation of the 1:1 complex. The pathway from fundamental studies to the use of these receptors for removing these anions from water has been tested. The receptive properties of 1 for phosphate are held when the extraction involves aqueous solutions containing individual ions. However, in mixtures containing both anions, the kinetics of the process and the selectivity of 1 for fluoride predominate and as a result, fluoride is better extracted than phosphate. The counter-ion effect on the removal process is assessed from Molecular Simulation studies. The removal of fluoride from phosphate is discussed taking into account existing technologies.

Groundwater fluoride contamination, probable release, and containment mechanisms: a review on Indian context

Fluoride contamination in the groundwater has got great attention in last few decades due to their toxicity, persistent capacity and accumulation in human bodies. There are several sources of fluoride in the environment and different pathways to enter in the drinking water resources, which is responsible for potential effect on human health. Presence of high concentration of fluoride ion in groundwater is a major issue and it makes the water unsuitable for drinking purpose. Availability of fluoride in groundwater indicates various geochemical processes and subsurface contamination of a particular area. Fluoride-bearing aquifers, geological factors, rate of weathering, ion-exchange reaction, residence time and leaching of subsurface contaminants are major responsible factors for availability of fluoride in groundwater. In India, several studies have reported that the groundwater of several states are contaminated with high fluoride. The undesirable level of fluoride in groundwater is one of the most natural groundwater quality problem, which affects large portion of arid and semiarid regions of India. Rajasthan, Andhra Pradesh, Telangana, Tamil Nadu, Gujarat, and West Bengal are the relatively high-fluoride-contaminated states in India. Chronic ingestion of high doses of fluoride-rich water leads to fluorosis on human and animal. Over 66 million Indian populations are at risk due to excess fluoride-contaminated water. Therefore, groundwater contamination subject to undesirable level of fluoride needs urgent attention to understand the role of geochemistry, hydrogeology and climatic factors along with anthropogenic inputs in fluoride pollution.

Provenance, prevalence and health perspective of co-occurrences of arsenic, fluoride and uranium in the aquifers of the Brahmaputra River floodplain

The present work focuses on understanding the provenance, prevalence and health perspective of As and F^- along with possible co-occurrence of uranium (U) in the aquifers of the Brahmaputra floodplains (BFP), India. Groundwater (n = 164) and sediment samples (n = 5) were obtained from the upper, middle and lower BFP. Energy dispersive spectroscopy (EDX) revealed the presence of As, U and Fe in the sediment matrix. Regression analysis showed a weaker relationship between As and F^- co-occurrence. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) suggested reductive dissolution of Fe (hydr)oxides responsible for As release in the BFP, especially in the upper and lower BFP. Bicarbonate appeared to compete with As oxyanions for adsorption on positively charged surfaces leading to As release. Arsenic desorption in presence of PO₄^3-, F^- and HCO₃^- at elevated pH appeared greatest in the upper BFP, suggesting the highest potential for co-occurrence. Co-occurrence, were mainly in isolated aquifers of the upper BFP owing to desorption of adsorbed As and F^- from Fe (hydr)oxides at higher pH. Weathering and dissolution of clay minerals in the upper BFP, and competitive desorption in presence of HCO₃^- and PO₄^3- in the middle and lower BFP, respectively, explain variabilities in F^- release. Amorphous Fe (hydr)oxides like ferrihydrite act as sinks of U. Concentrations of As and F^- will likely increase in the future as projected from the saturated levels of goethite and ferrihydrite. Hazard indices (HI) revealed that children (3-8 years) were at greater health risk than adults.

Risk Assessment of Fluoride Intake from Tea in the Republic of Ireland and its Implications for Public Health and Water Fluoridation

The Republic of Ireland (RoI) is the only European Country with a mandatory national legislation requiring artificial fluoridation of drinking water and has the highest per capita consumption of black tea in the world. Tea is a hyperaccumulator of fluoride and chronic fluoride intake is associated with multiple negative health outcomes. In this study, fifty four brands of the commercially available black tea bag products were purchased and the fluoride level in tea infusions tested by an ion-selective electrode method. The fluoride content in all brands tested ranged from 1.6 to 6.1 mg/L, with a mean value of 3.3 mg/L. According to our risk assessment it is evident that the general population in the RoI is at a high risk of chronic fluoride exposure and associated adverse health effects based on established reference values. We conclude that the culture of habitual tea drinking in the RoI indicates that the total cumulative dietary fluoride intake in the general population could readily exceed the levels known to cause chronic fluoride intoxication. Evidence suggests that excessive fluoride intake may be contributing to a wide range of adverse health effects. Therefore from a public health perspective, it would seem prudent and sensible that risk reduction measures be implemented to reduce the total body burden of fluoride in the population.

Recommendations for fluoride limits in drinking water based on estimated daily fluoride intake in the Upper East Region, Ghana

Both dental and skeletal fluorosis caused by high fluoride intake are serious public health concerns around the world. Fluorosis is particularly pronounced in developing countries where elevated concentrations of naturally occurring fluoride are present in the drinking water, which is the primary route of exposure. The World Health Organization recommended limit of fluoride in drinking water is 1.5 mg F(-) L(-1), which is also the upper limit for fluoride in drinking water for several other countries such as Canada, China, India, Australia, and the European Union. In the United States the enforceable limit is much higher at 4 mg F(-) L(-1), which is intended to prevent severe skeletal fluorosis but does not protect against dental fluorosis. Many countries, including the United States, also have notably lower unenforced recommended limits to protect against dental fluorosis. One consideration in determining the optimum fluoride concentration in drinking water is daily water intake, which can be high in hot climates such as in northern Ghana. The results of this study show that average water intake is about two times higher in Ghana than in more temperate climates and, as a result, the fluoride intake is higher. The results also indicate that to protect the Ghanaian population against dental fluorosis, the maximum concentration of fluoride in drinking water for children under 6-8 years should be 0.6 mg F(-) L(-1) (and lower in the first two years of life), and the limit for older children and adults should be 1.0 mg F(-) L(-1). However, when considering that water treatment is not cost-free, the most widely recommended limit of 1.5 mg F(-) L(-1) - which is currently the limit in Ghana--may be appropriate for older children and adults since they are not vulnerable to dental fluorosis once the tooth enamel is formed.