Distribution Of Fluoride Research Articles

Determination of bioavailable fluoride from sepiolite by “in vivo” digestibility assays

This work presents a study of the bioavailability and distribution of fluoride in tissues of animals (Wistar rats) which were fed with a poultry feeding that contains sepiolite as an additive. The determination of fluoride concentration was carried out by potentiometric measurements using a fluoride selective electrode. The quantification was done using the standard addition method with enough accuracy and precision in all the assays. The results demonstrate that fluoride present in sepiolite is not bioavailable. The digestion process does not extract all the fluoride from sepiolite, so sepiolite can be use in poultry feedings without any risk. These studies have contributed to the discussions at EU level about extraction procedures and F − determination in feed material of mineral origin.

The distribution and hydrogeological controls of fluoride in the groundwater of central Ethiopian rift and adjacent highlands

Occurrence of fluoride (F) in groundwater has drawn worldwide attention, since it has considerable impact on human health. In Ethiopia high concentrations of F in groundwaters used for community water supply have resulted in extensive dental and skeletal fluorosis. As a part of a broader study, the distribution of F in groundwater has been investigated, and compared with bedrock geology and pertinent hydrochemical variables. The result indicates extreme spatial variations. High F concentration is often associated with active and sub-active regional thermal fields and acidic volcanics within high temperature rift floor. Variations in F can also be related to changes in calcium concentration resulting from dissolution of calcium minerals and mixing with waters of different chemical composition originated from variable hydrogeological environment across the rift valley. The concentration of F dramatically declines from the rift towards the highlands with the exception of scattered points associated with thermal springs confined in local volcanic centers. There are also interactions of F-rich alkaline lakes and the surrounding groundwater. Meteoric waters recharging volcanic aquifers become enriched with respect to F along the groundwater flow path from highland recharge areas to rift discharge areas. Locally wells drilled along large rift faults acting as conduits of fresh highland waters show relatively lower F. These areas are likely to be possible sources of better quality waters within the rift. The result of this study has important implications on site selection for water well drilling.

Urinary Fluoride Reference Values Determined by a Fluoride Ion Selective Electrode

As fluoride has a very short half-life in the body and the major route for fluoride excretion is via the kidney, human exposure is best measured in urine, where the concentration is expected to be highest. The urinary fluoride concentrations of 167 healthy Japanese adults were determined by means of a fluoride ion selective electrode. When the results were corrected for a specific gravity rho = 1.024 g cm-3, the histogram of urinary fluoride concentrations highly skewed toward low values with sharp peakedness (skewness = 1.56, kurtosis = 3.08). The normality of the log-transformed histogram (skewness = 0.12, kurtosis = 0.07) and the straight line on log-probability paper clearly showed a key feature of lognormal distribution of urinary fluoride. A geometric mean (GM) of 613.8 microg/l and 95% confidential interval (CI) of 241.0-1633.1 microg/l were established as reference values for urinary fluoride. The results presented in this study will be useful as guidelines for the biological monitoring of fluoride in normal subjects and individuals at risk of occupational or environmental fluoride exposure.

Fluoride distribution in the environment along the gradient of a phosphate-fertilizer production emission (southern Brazil)

Airborne fluoride was determined in the rainwater, surface soil and groundwater along a gradient of emission of a phosphate fertilizer factory in Rio Grande, southern Brazil. Concentrations of fluoride in rainwater and groundwater achieved 3 mg l(-1) and 5 mg l(-1), respectively, and were dependent on pH. The fluoride deposited from emissions accumulated in a superficial horizon of soil in quantities comparable to those in the manufactured end-products--up to 23,000 mg kg(-1). Fluoride distribution in the environment is controlled by physical-chemical parameters of emission, rain intensity and soil properties. The highest fluoride concentrations were registered at a close distance of up to 2 km from the factory. The distribution of fluoride in groundwater resembled the same distribution in rainwater due to the high permeability of the local soils. Fluoride penetration to the groundwater also depended on the type of vegetation cover. The groundwater in woodland areas was less affected by contamination of fluoride than in the grassland areas, most probably because of the influence of eucalyptus throughfall, which increases the pH of wet precipitates.

Fluoride distribution in electrocoagulation defluoridation process

Electrocoagulation (EC) is an effective process to remove fluoride from water, but few of scientific literatures explore its inside mechanism. A new approach was used in this study to investigate fluoride distribution in the EC defluoridation process, which divided the fluoride into three parts: remained in water, removed by electrodes, and adsorbed on hydroxide aluminum flocs. The fluoride distribution was investigated in terms of several critical parameters such as pH, charge loading, current density and initial fluoride concentration. The experimental results showed that the removal by electrodes was primarily responsible for the high defluoridation efficiency, and the adsorption by hydroxide aluminum flocs gave a secondary effect. The parameters affected the efficiencies of defluoridation in a way of changing the fluoride distribution in the EC process. A chemical complex of Al n (OH) m F k 3 n− m− k was formulated to explain the mechanism inside the EC defluoridation process. The new approach provides a detailed insight of the electrocondensation effect, which helps to gain more scientific comprehension about the cooperation between electrochemical and chemical ways occurring inside the EC process.

A study of fluoride groundwater occurrence in Nathenje, Lilongwe, Malawi

A study was carried out to determine fluoride concentration in groundwaters of Nathenje area situated in Lilongwe District in the central region of Malawi. Water samples were collected from 176 boreholes and shallow wells during different months in 2001 and 2002. Samples were then analysed for fluoride by using a fluoride electrode and an ion selective meter. The results showed that fluoride concentrations for the rainy season varied from <0.5 to 6.98 ± 0.01 mg/l with 52.9% of the boreholes above the World Health Organisation (WHO) maximum permissible limit of 1.5 mg/l. Fluoride concentrations for dry season ranged from <0.5 to 7.02 ± 0.02 mg/l with 50.8% of boreholes above 1.5 mg/l. Fluoride concentrations for the two seasons were significantly different from each other ( p < 0.05). Fluoride data was used to produce a fluoride distribution map. From the map, it was observed that fluoride concentrations in this area followed a pattern. The central part of Nathenje had high fluoride concentration of between 2 and 7.02 mg/l and these high fluoride values seemed to extend eastwards beyond the boundary of the study area. However, the southern and western parts had <1 mg/l of fluoride. The high groundwater fluoride values seem to be associated with the weathered basement complex containing biotite that is a probable source of fluoride. The other suspected sources of fluoride in Nathenje groundwater could be due to the dissolution of hornblende, fluorite and amphibole, which are reported to occur in rocks and soils in this area. There was evidence of dental fluorosis in areas where the fluoride concentration was high.

Total fluoride in Guangdong soil profiles, China: Spatial distribution and vertical variation

A total of 260 soil profiles were reported to investigate the fluoride distribution and vertical variation in Guangdong province. The soil fluoride contents followed an approximately lognormal distribution. Although the soil fluoride geometric mean concentration of 407 mg/kg is lower than that of China, its content varied from 87 to 2860 mg/kg. An upper baseline concentration of 688 mg/kg was estimated for surface soils. In A-, B-, and C-horizon soil fluoride spatial distribution presented similar patterns that high fluoride concentration mainly located in limestone, purple shale, and sandshale areas, indicated that soil fluoride spatial distribution was primarily dependent on the regional bedrock properties rather than anthropogenic inputs. From A- to C- horizon soil fluoride geometric mean concentration had an increasing tendency of 407, 448, and 465 mg/kg. This vertical variation was the result of the intensive eluviation under the subtropical hydrothermal condition, and had closely related with soil properties, such as lower organic matters and clay content variations. Moreover, the soil degradation and erosion was also an important pathway of soil fluoride movement, as a result the soil fluoride exported into surface and groundwaters would reach about 4.1 × 10 4 t year − 1 in the study area.

Distribution of fluoride in groundwater and its suitability assessment for drinking purpose

Groundwater samples collected either from the bore-wells (forms a part of municipal water supply) or from the hand pumps (direct consumption) were analysed for fluoride in Hisar city, India. The results indicate considerable variations among the analysed groundwater samples and the concentration of fluoride ranged from 0.03 – 16.6 mg/l. In most of the groundwater samples the concentration of fluoride was found to be moderately higher, when compared to the WHO standard for drinking water, which may lead to associated health risks in urban population, if the groundwater is being used without proper treatment. Furthermore, it is suggested that the sources of municipal water supply must be established in a region where an adequate level of fluoride was observed.

Fluoride occurrence in publicly supplied drinking water in Estonia

A study was undertaken to examine the content and spatial distribution of fluoride in drinking water. Water samples (735) from public water systems covering all Estonian territory were analysed using SPADNS method. In order to specify the natural source of fluoride, the chemistry data from five aquifer systems utilised for water supply were included into the study. Fluoride concentrations in tap water, to a great extent, ranged from 0.01 to 6.95 mg/l. Drinking water in southern Estonia, where terrigenous Middle-Devonian aquifer system is exploited, has a fluoride concentration lower than recommended level (0.5 mg/l), thus promoting susceptibility to dental caries. The western part of the country is supplied by water with excess fluoride content (1.5–6.9 mg/l). Groundwater abstracted for drinking purposes originates from Ordovician and Silurian carbonate rocks. The content of fluoride in Silurian–Ordovician aquifer system is associated with the groundwater abstraction depth and the main controlling factors of dissolved fluoride are the pH value and the chemical type of water.

Vanadium in ground water from Mt. Fuji: Does it have health effect on habitants around the mountain?

A study was carded out in the Nathenje area in order to determine fluoride concentrations in groundwater and to investigate the occurrence of dental fluorosis in school children. From a fluoride distribution map, it was observed that the central part of Nathenje had high fluoride concentration of between 2 mg/L and 7.02 mg/L. The southern and western parts had less than 1 mg/L. About 52% of the groundwater supplies had fluoride concentrations are above the Word Health Organization maximum permissible limit of 1.5 mg/L. Fluoride concentrations for the rainy season varied from <0.5 to 6.984-0.01 mg/L with 52.9% of the boreholes above the 1.5 mg/L. Fluoride for dry season ranged from <0.5 to 7.024-0.02 mg/L with 50.8% of the boreholes above 1.5 mg/L. Fluoride concentrations remained almost constant during the two seasons of the study period. A social survey revealed that 68.5% of children had dental fluorosis from areas with greater than 4.95 mg/L fluoride. About 25% were affected in areas with an average content of 1.85 mg/L. No occurrence of dental fluorosis was detected in children from areas with less than 1 mg/L fluoride. It was therefore concluded that fluoride is a serious contaminant of groundwater in Nathenje where most of the groundwater contains fluoride higher than World Health Organization acceptable levels. These high fluoride values seem to be associated with the weathered basement complex containing biotite that is a probable source of fluoride. The other suspected sources of fluoride in Nathenje groundwater could be due to the dissolution of hornblende, fluorite and amphibole, which are reported to occur in rocks and soils. The fluoride concentrations in Nathenje groundwater vary from less than 0.5 mg/L to 7.02 mg/L probably due to varying concentrations of fluoride-bearing minerals and their dissolution rate. It was observed that the central part of the Nathenje area where groundwater contains high fluoride content, about 68.5% of children has suffered dental fluorosis. This shows that excess fluoride occurrence in groundwater supplies causes dental fluorosis among children in this area. Based upon the results of this study, it was recommended that further studies should be done on the genesis of fluoride in groundwater. It was also recommended that water quality analyses should be carried out during borehole construction, and monitoring of boreholes should be done after the boreholes have been handed over to the communities.

Evaluation of a New Fluoride-releasing One-step Adhesive

In this study, a newly developed S-PRG (surface pre-reacted glass-ionomer) filler-containing one-step adhesive, called SI (SI-IB551, Prototype), was evaluated regarding its fluoride release behavior. As a result, fluoride ion distribution in the tooth structures and acid resistance of cavity margins were also evaluated. In addition, Absolute (a fluoride-releasing one-step adhesive; AB) was evaluated in comparison to G-Bond (a non-fluoride-releasing one-step adhesive; GB) which was used as a negative control. Concentration of fluoride released was measured using a fluoride ion selective electrode after immersion of each material in distilled water. Fluoride distribution in tooth-adhesive interfacial areas was examined with EPMA following cavity preparation in human premolars and having treated resin restorations with each material. To evaluate acid resistance, restored specimens were immersed in an acetic acid buffer (0.2 M, pH 4.5) for 12 hours and then the cavity margins were observed using scanning electron microscopy. Amounts of fluoride released from AB and SI were significantly greater than that from GB. Further, significant differences in fluoride release were detected between AB and SI. A layer of increased fluoride density was clearly detected at the enamel- and dentin-SI interfaces. In terms of acid resistance, an acid resistance zone was also formed adjacent to the tooth-adhesive interface of AB and SI specimens. However, in GB specimen, acid resistance zone was not observed. These findings suggested that one-step adhesives displayed a favorable fluoride release property, thereby contributing positively to inhibition of recurrent caries.

The geographic distribution of fluoride in surface and groundwater in Ethiopia with an emphasis on the Rift Valley

This paper analyzes the most extensive database on fluoride distribution in Ethiopia. Of the total 1438 water samples tested, 24.2% had fluoride concentrations above the 1.5 mg/l recommended optimum concentration recommended by WHO. Regionally, by far the highest fluoride levels were recorded in the Rift Valley, where 41.2% of all samples exceeded the 1.5 mg/l level. Only 1.0% of the samples from the central and northwestern highlands and 10.0% in the southeastern highlands exceeded 1.5 mg/l. Larger proportions of deep wells (50.0%) and hot springs (90.0%) than shallow wells (27.2%) and cold springs (12.6%) exceeded the 1.5 mg/l level. The highest fluoride concentrations were recorded for Rift Valley lakes Shala (264.0 mg/l) and Abijata (202.4 mg/l) and the lowest in Lake Tana, and rivers, wells and springs in the highlands. The fluoride concentrations of the Awash River, which originates in the highlands and flows through the Rift Valley, increase downstream, giving concern over the current diversion of high-fluoride water from Lake Beseka. Of the various flourosis prevention methods tried in Ethiopia, the treatment of surface water has been shown to be the most feasible and effective for towns and large commercial farms in the Rift Valley, although defluoridation methods should be considered for smaller rural communities.

Gramíneas bioindicadoras da presença de flúor em regiões tropicais

Ten species of tropical grasses, Andropogon gayanus Kunth cv. Planaltina, Panicum maximum Jacq. cv. Coloniao, Panicum maximum Jacq. cv. Tobiata, Chloris gayana Kunth, Eragrostis curvula (Schrad.) Nees, Paspalum notatum Flug. cv. Pensacola, Hiparrhenia rufa (Nees) Stapf., Melinis minutiflora Pal. de Beauv., Brachiaria decumbens Stapf., Brachiaria humidicola (Rendle) Schw. and Lolium multiflorum ssp. italicum var. lema were treated with simulated rain containing 5, 10, and 15 g.m-3 of fluoride, in order to evaluate their relative sensitivity and potential as bioindicator for fluoride under tropical conditions. The plants were cultivated according to standardized techniques for active bioindication. The development of visible damages, the accumulation and distribution of fluoride and the dry weight yield were used to assess the effects of the element on the plants. All studied species showed distinct pattern of fluoride accumulation, fluorine contents above the accepted toxic levels for sensitive species (30 µg.g-1) and a good correlation between fluoride content and the phytotoxicity index, except for Brachiaria humidicola. Chloris gayana and Panicum maximum cv. Coloniao were the species that better adapted to the standardized cultivation techniques, based on their growth rates, sprout homogeneity and fast appearance of visible symptoms (chlorosis and necrosis). Fluoride effects on stomatal conductance, CO2 assimilation and dry weight yield were also evaluated in these two species, with potential for bioindication use. The results indicate Panicum maximum cv Coloniao as a responsive bioindicator while Chloris gayana as a tolerant species, similarly to L. multiflorum.

Effect of three fluoride agents on remineralization and fluoride uptake on enamel lesion

This study is to compare the fluoride uptake of three fluoride agents and the effect of remineralization on artificial enamel lesions. Eight human third molars were all divided into four slabs. The slabs were randomly assigned to the following four groups: group A (9,040 ppm F, APF gel), group B (968 ppm F, SnF 2 home gel), group C (22,600 ppm F, fluoride varnish, FV) and a control group. After 72-hour demineralizing and 10-day pH-cycling period with the application of corresponding fluorides. The distribution of fluoride and mineral change was analyzed with EPMA and CMR respectively. There was a significant increase in the amount of F uptake after the application of the three fluoride agents compared to the control group. Group A showed an extremely greater F uptake compared to group C and B. The amount of F uptake from group C was greater than that of group B. The three tested groups showed signs of significantly greater amounts of remineralization as compared to the control group. Remineralization of group C was detected to be the greatest, followed by group A and group B, but there was no significant difference in them under statistical analysis. It can be concluded that all of the tested agents were effective in regaining mineral loss. FV may be recommended as a professional topical fluoride. It is as effective, if not more so, as traditionally used APF gel. Also 0.4% SnF 2 home gel is an efficient self-applied topical fluoride for daily use.

Fluoride tablet programs in healthy elderly subjects: distribution of fluoride in saliva and plaque with tablets in different sites

Based on root caries data and oral sugar clearance pattern, vestibular surfaces of upper incisors and lower molars may be regarded as risk areas along with the proximal surfaces. The aim of the present study was to use this information in improving fluoride tablet programs for the elderly. Six healthy elderly males with full dental arches took part. Flavored and unflavored tablets dissolved passively either under the tongue or in the vestibule close to the root caries risk areas. Salivary fluoride was determined at five to six intra-oral sites with a micro-sampling technique at intervals up to 10 min tablet use. Plaque samples were collected from single tooth surfaces before and after tablet use, and analyzed for total fluoride and total protein by micro-techniques. Salivary fluoride exposure to root caries risk areas was strongly increased when fluoride tablets were placed in the vestibule in these areas. The unflavored tablet gave higher fluoride retention in saliva than did the flavored brand. Plaque fluoride levels tended to be above baseline in the first couple of hours after tablet use, and then to decline. In the caries risk areas, at vestibular surfaces of lower posterior and upper incisor teeth, most of the fluoride taken up in plaque had been lost after 5 h and a bread meal, whereas in the non-risk areas it was largely retained. The study demonstrated that fluoride exposures to the vestibular caries risk areas can be strongly increased by placing fluoride tablets close to them. An unflavored tablet seemed to give higher exposures than a flavored one. The rapid loss of fluoride from plaque in slow clearance risk areas indicates that more than one daily treatment would be required for elderly caries risk subjects.

Estimation of fluoride distribution in the mandible and teeth of the red deer (Cervus elaphus L.) from industrially polluted areas in Poland

Animals from areas contaminated by industrial emissions containing fluoride may accumulate it predominantly in hard tissues. Therefore, an analysis was performed for the determination of fluoride content in mandibles and teeth of deer living at large in different areas in Western Pomerania (Poland). Samples of hard tissues obtained with a dental drill, were dissolved in perchloric acid and analyzed for fluoride content with an ion-selective electrode. Using the Generalized Regression Neural Network (GRNN), it was possible to arrange definite variables according to their order of importance concerning the fluoride mean content in investigated bone material. Parametric analysis revealed in which sites of mandibles and teeth the fluoride accumulation was the highest. In our calculation, the traditional statistic as well as artificial neural network was applied. One of the interesting properties of fluoride is its balancing accumulation in the hard and soft tissues. In this paper, we decided estimate how the changeable doses of fluoride in natural environment influence on fluoride distribution and accumulation in the examined sites of mandible and teeth. The material consist of 103 mandibles of red deer (Cervus elaphus L.) from five forestry districts of Western Pomerania in Poland, which are located near or far away from two major industrial plants: Police Chemical Work and the Dolna Odra Coal Power Plant. Samples (10 mg of powdered bone or tooth) were dissolved in perchloric acid and the fluoride content was determined with an ion-selective electrode. Comparisons were done with the Statistica 5.5 and Statistica Neural Networks. Animals living in Western Pomerania (Poland) have high fluoride contents in their bones. Fluoride accumulation in mandibles and teeth is irregular. The higher content of fluoride show incisal area, but coronoid process of the mandible was not sensitive to different exposure of environmental fluoride at all. Parametric analysis revealed that the accumulation pattern of fluorine was different in the two groups of deer. Many biological and environmental factors may influence on incessant fluoride accumulation in osseous tissue of ruminants living at large. The use of artificial neural networks enables a more accurate insight into the process of fluorine accumulation in the mandible and teeth and helps in the ranking of factors influencing this process.

MRI of the spine in endemic fluorosis

目的 评价MRI在地方性氟骨症脊柱病变诊断中的作用.方法对81例地方性氟骨症的脊柱MRI进行分析和与X线比较.结果所有椎体内脂肪含量减少和分布不均,在T1WI上信号强度表现为均匀或不均匀性减低,其信号减低程度与X线骨密度的增高程度相比较无明确相关性.32例C3～7椎体的T1WI信号强度平均值明显低于100例对照组(P<0.001).81例中后纵韧带和黄韧带骨化71例(88%),其中后纵韧带骨化35例(43%),黄韧带骨化8例(10%),后纵韧带和黄韧带骨化28例(35%),与X平片所显示的相同.在T1WI上63例后纵韧带骨化和36例黄韧带骨化有中等信号强度区者分别为32例(51%)和31例(86%).81例中椎间盘突出68例(84%),椎间盘变性57例(70%),椎管狭窄75例(92%),脊髓受压63例(78%),其中脊髓内有病理学改变28例(35%).X线测量57例颈椎椎管前后径<9 mm(以此推断脊髓受压)41例(71.92%),MRI显示脊髓受压48例(84.21%,P=0.115).57例颈椎椎间盘后突出51例(89.47%),明显高于对照组(62%)(P<0.001);椎间盘变性37例(64.91%),与对照组(37%)相比较差异有非常显著性意义(P=0.001).结论 MRI显示地方性氟骨症的椎体信号强度均匀或不均匀性减低,可反应成骨活动增强程度和氟化钙及骨髓内脂肪含量及分布.MRI对显示脊髓受压,脊髓内病理学改变和椎间盘突出、变性优于X线。

Site-specific Fluoride Distribution of Enamel Surfaces in Extracted Permanent Teeth Obtained from Chinese Subjects

Site-specific Fluoride Distribution of Enamel Surfaces in Extracted Permanent Teeth Obtained from Chinese Subjects

Distribution and risk assessment of fluoride in drinking water in the west plain region of Jilin province, China.

The west plain region of Jilin province of northeast China is one of the typical endemic fluorosis areas caused by drinking water for many years. Investigations of hydrogeological and ecoenvironmental conditions as well as endemic fluorosis were conducted in 1998. Results show that the ground water, especially, the water in the unconfined aquifer is the main source of drinking water for local residents. The fluoride concentration in groundwater in the unconfined aquifers is higher than that in the confined aquifer in the west plain of Jilin province. The fluoride concentration in the unconfined aquifer can be used to classify the plain into fluoride deficient area, optimum area and excess area, which trend from west to east. High fluoride (>1.0 mg L(-1)) in drinking water resulted in dental and skeletal fluorosis in local residents (children and pregnant women). There exists a positive correlation between fluoride concentration in the drinking water and the morbidities of endemic fluorosis disease (r1 = 0.781, r2 = 0.872). Health risks associated with fluoride concentration in drinking water are assessed. It has been determined that fluoride concentration in excess of 1.0 mg L(-1) exposes residents to high health risks based on risk identification. The study area is classified into five health risk classes as shown in Figure 4. The risk indexes of this area more than 1.0 are accounted for 68% of the total west plain region.

Fluoride content in bones of Adelie penguins and environmental media in Antarctica.

Fluoride (F) distribution and its effects (fluorosis) were investigated in Antarctica. Droppings (L) excreta selected of aquatic birds, lake water, soil and moss (Polytrichum alpinum) showed a high F concentration. Although bones of Adelie penguin (Pygiscelis adeliae) and skua (Catharacta maccormicki) showed exceptionally very high F concentration in the range of 832 to 7187 mg kg(-1), their radiographs did not show any evidence of skeletal fluorosis. The possible reason and geochemical aspects of F in Antarctica region are discussed.