Low Levels Of Fluoride Research Articles

Analysis of environmental materials using spectroscopic methods

Background levels of environmental materials are the most crucial to be examined for the purpose of environmental monitoring. Lake Mashu water and mussel tissue powders from an unpolluted area are selected as the example for this study. ICP emission spectrometry with a preconcentration procedure by 8-hydroxyquinoline complexation and graphite furnace atomic absorption are among various spectroscopic methods used for the analyses. Colorimetry with an optical fiber type of a total reflection long capillary cell has been found effective for low level fluoride determination in drinking water.

Enhanced fluoride uptake from mouthrinses.

It has been shown in laboratory and animal studies that tooth enamel becomes considerably more reactive toward low levels of fluoride after receiving pre-treatment which forms dicalcium phosphate dihydrate (DCPD) in the enamel as an intermediate. This in vitro study was undertaken to determine the effect on human enamel fluoride uptake of incorporating DCPD-forming rinses into a conventional fluoride rinsing program. In one group, enamel samples received a one-minute rinse with 0.2% NaF each day for 20 days. Samples in the second group were treated identically, except that they were also given a one-minute DCPD-forming rinse prior to the first, sixth, eleventh, and sixteenth fluoride rinses. At the end of the rinsing program, all samples were washed in 1 M KOH to remove labile fluorides. The enamel biopsy data showed that the fluoride uptake resulting from 0.2% NaF alone was not statistically significant, whereas uptake produced by the DCPD-forming plus NaF rinses was significant. The results suggest that the DCPD-forming rinse may improve the efficacy of fluoride rinse programs.

Apparent Stimulation of Tree Growth by Low Ambient Levels of Fluoride in the Atmosphere

Fluoride emissions from the aluminum smelter of Kitimat, British Columbia have been affecting the adjacent forests since 1954. A review is given of this study conducted from 1954 to 1979. The effects were determined on the foliage analysis, lichen growth, observed plume/air flow and topography. The trees in the plots were measured and recorded by species, diameter, height, and condition. The areas of forest exposed to a very low level of fluoride in the ambient air showed growth rates higher than expected under normal conditions. The effect of the emissions in the inner zone was to reduce the growth rate by 28.1%. The growth rate of the outer zone was reduced by 19.0%. The surround zone showed a small loss of growth at 2.2% At the 1979 remeasurement of the growth from 1974 to 1979, it was found that growth reduction in the inner zone had continued, but the outer and surround zones now showed increases in growth of 2.8% and 13.6% respectively. During the period 1974-1979, the rate of fluoride emission of the smelter had been reduced by 64% of what it had been in the preceding period. It is possible that certain low levels of fluoride may stimulatemore » tree growth without prior injury by higher levels of fluoride. Analysis of results following 1984 remeasurement of sample trees may provide greater understanding of this situation. 1 figure, 1 table.« less

Determination of low-level fluoride ion in natural water by ion-selective electrode after coprecipitation with aluminum phosphate

Determination of low-level fluoride ion in natural water by ion-selective electrode after coprecipitation with aluminum phosphate

Role of Fluoride in Formation of Urinary Calculi: Studies in Rats

The effect of fluoride on urinary caculi formation in young rats was investigated. Two studies, in which rats received diets that included either higher calcium (9 g/kg diet) or normal calcium (5 g/kg diet), were conducted. At each level of calcium, one group of rats received a high level of fluoride and another a low level of fluoride in the diet. Rats ingesting high fluoride diets exhibited a higher incidence of crystalluria and bladder stones compared with those receiving low fluoride diets. However, compared with higher calcium diets, normal calcium diets delayed the appearance of crystalluria and produced smaller calculi. Calcium and oxalate were the major components of the calculi. Calculi of rats fed the higher calcium and high fluoride diet contained relatively less protein and more calcium compared with calculi formed in rats ingesting the higher calcium and low fluoride diet. The concentration of fluoride in calculi from rats fed high fluoride diets was significantly higher than that of calculi from rats fed low fluoride diets. A significant positive correlation between calcium and fluoride concentration of calculi was observed in rats fed the higher calcium diet only. These studies indicate that ingestion of excess fluoride facilitates calcium oxalate crystalluria and promotes the formation of bladder stones in rats, under the experimental conditions used.fluoride urinary calculi crystalluria bladder stones

Chemical composition of some tissues of the Antarctic fish Notothenia rossii marmorata, fischer 1885

Muscle, liver, stomach, intestinal tract and pyloric caeca of the Antarctic fish Notothenia rossii marmorata, Fischer 1885, were analysed for dry matter, crude protein, carbohydrate, total lipids, ash, chloride, phosphorus and fluoride. It was found that the levels of these classes of substance varied considerably within ten fishes of a pre-spawning community. The highest level of protein was found in the stomach (80·8% mean value on a dry weight basis) and the lowest in the liver (39·6%); for total lipids in the liver and stomach the situation was reversed with the relevant figures being 40·8% and 11·27%, respectively. The pyloric caeca showed a maximum of ash content (6·34%), whilst only 3·92% was found in the liver. The liver was extremely rich in carbohydrates (8·22%) whilst, at 1·64%, the muscle contained least. Although N. rossii marmorata mainly feeds on the fluoride-containing krill ( Euphausia superba Dana), the tissues investigated showed only a low level of fluoride (10–40 ppm).

The effect of fluoride in the remineralization of enamel caries and caries-like lesions in vitro.

Remineralization occurs naturally during the formation of a carious lesion in human dental enamel and is seen in the form of two of the four classical histological zones of the lesion. Exposure of small lesions to a synthetic calcifying in vitro results in a significant increase in remineralization of the lesion. The degree of remineralization achieved depends upon the presence of fluoride ions in the calcifying fluid and its degree of supersaturation. It appears that only low levels of fluoride are required to trigger the mechanism of remineralization; raising the fluoride level further does not result in a greater degree of remineralization. The calcium ion concentration of the calcifying fluid is critical with respect to determining which components are supersaturated and which in turn determines the degree of remineralization achieved. With levels of 3.0 mM calcium only the superficial region of the lesion is remineralized whereas with a calcium concentration of 1.0 mM, remineralization occurs in depth. It is hoped that studies on remineralization phenomena will provide further insight into the mechanisms of caries formation and be the basis for a more powerful and effective form of caries prevention.

Reduction in caries after 7 years of water fluoridation under climatic conditions in Cuba.

A study on 614 children (aged 6–13) showed caries reduction in La Salud, Cuba, after 7 years of water fluoridation (0.7 ± 0.1 ppm F). Despite this relatively low fluoride level the caries-inhibiting effect was comparable with a similar study carried out in a temperate climate. The low incidence of mottling in artificially fluoridated and naturally high F areas would seem to justify an increase in the fluoride concentration of water supplies to 0.9 ± 0.1 ppmF.

Dissolution rate behavior of fluoridated apatite pellets.

The dissolution rate of synthetic fluoridated apatite pellets with various fluoride content was measured in acetate buffer solution at pH 4.0. The dissolution rate decreased with degree of fluoridation. The rate decreased greatly at low fluoride levels. The experimental data were analyzed by means of a diffusion-controlled model and compared with the solubility data. This model showed that the initial dissolution rate is greatly affected by both the solubility and the overall mass transfer resistance. Overall mass transfer resistance is affected by fluoride content.

Major ion chemistry in a tropical African lake basin

SUMMARY. The amount of water lost by seepage from Lake Naivasha, calculated as the residual in the water budget, was 5 (1973), 11 (1974) and 20% (1975) of the total water loss. Direct measurements of seepage in nearshore shallows indicated that water entered the lake via ground‐water seepage in the northern portion and left the lake in the southern portion. Naivasha lies in a topographic closed basin but is hydrologically a seepage lake; it is distinctive among the lakes lying in the endorheic rift valleys of Ethiopia, Kenya and Tanzania because the water is fresh.The mean chemical composition (mg l−1) of bulk precipitation collected on two transects across the rift valley near L. Naivasha and at three stations near Nairobi was: Na, 0.54, K, 0.31; Ca, 0.19; Mg, 0.23; SO4, 0.72 and Cl, 0.41. The major inflow, the Malewa River, was largely a solution of bicarbonate (1.15 m‐equiv, l−1), sodium (9 mg l−1) and calcium (8 mg l−1) and carried a total dissolved solid load (kg ha−1) of 62 (1973) and 120 (1974). Total dissolved solids, sodium, calcium and bicarbonate concentrations were inversely related to discharge.Among the standing waters in the Naivasha basin, sodium and bicarbonate are predominant and the mean total dissolved solute content (mg l−1) increased from a low under the northern papyrus swamp (217) to intermediate values in L. Naivasha (329), the nearshore lagoons (367) and Crescent Island basin (394) to a high in Oloidien Lake (831). Ion ratios and stability field diagrams indicated that calcite is formed in the Crescent Island basin and Oloidien Lake. Calcite was detected in the sediments of the two basins. Ion ratios also indicated that sulphate was retained in the sediments of the northern papyrus swamp.Several factors combine to keep L. Naivasha's water fresh. A large fraction of the water supplied to the lake comes from dilute rivers and rain. The lake does not lie in a closed basin, but loses water and solutes via seepage. Exchanges with sediments both in the pelagic and littoral regions of the lake are the major routes for solute movement and biochemical sedimentation is a major factor in removal of silica. Both geochemical and biochemical sedimentation account for much of the potassium, calcium, magnesium and bicarbonate removal. Only low levels of the conservative ions, sodium and chloride, are taken up by the sediments, while very low levels of sulphate and fluoride are actually released.

ChemInform Abstract: THE EFFECT OF FLUORIDE, ZINC, STRONTIUM, MAGNESIUM AND IRON ON THE CRYSTAL‐STRUCTURAL DISORDER IN SYNTHETIC CARBONATED APATITES

AbstractIn Gegenwart von Spuren an Metallen und Fluorid gefällte Carbonata.patite zeigen eine wesentlich geringere Unordnung als einfache Carbonatapatite, d.h." die Reaktivität von Zahnschmelz wird erheblich beeinflußt. Die wirksamste Kombination ist hierfür Zn + F ′.

Fluoride intake of young male adults in the United States

The total daily fluoride intake for young male adults living in four geographical areas of the United States has been estimated by the analysis of "market basket collections" obtained in 1975 and 1977. The fluoride intake in 1975 vaired from 0.912 mg/day in an unfluoridated city (Kansas City, Mo.) to 1.720 mg/day in a fluoridated city (Atlanta, Ga.). The 1977 collection from San Francisco, Calif. contained more fluoride (1.636 mg/day) than the 1975 collection (1.213 mg/day). The level of intake found in this study is less than that reported by San Filippo and Battistone (Clin. Chem. Acta 31: 453, 1971) who analyzed similar collections from Baltimore, Md. in 1967 to 1968 (2.09 to 2.34 mg/day). This study, as well as the earlier one, indicates that relatively low levels of fluoride are being consumed in the United States by the young adult male 16 to 19 years of age.

The effect of fluoride, zinc, strontium, magnesium and iron on the crystal-structural disorder in synthetic carbonated apatites

The purpose of this study was to investigate the effect of trace metals and fluoride on structural disorder in carbonated apatites and to consider the relevance of the results to dental apatite (enamel). Synthetic carbonated apatites were precipitated in the presence of low levels of zinc, magnesium, strontium, iron and fluoride. Crystal imperfection, as indicated by X-ray peak half-widths, was altered markedly by the substituents. Fluoride alone was effective and zinc- fluoride was the most effective combination in compensating for disorder caused by carbonate inclusion. These results show that disorder induced by carbonate inclusion can be modified greatly by appropriate elements. Trace-element inclusions may therefore markedly affect dental enamel reactivity. Carbonate content alone cannot be used as an indicator of the reactivity of apatite or of the potential susceptibility of dental enamel to caries.

Preconcentration of low-level fluoride ion in natural water samples with zirconium-loaded cation exchange resin column

Preconcentration of low-level fluoride ion in natural water samples with zirconium-loaded cation exchange resin column

Buffers for fluoride electrode calibration in the low concentration range

Thorium-buffered fluoride standards for calibration of fluoride electrodes at low fluoride concentration are described. Fluoride electrodes give Nernstian response down to very low fluoride levels, but the practical limit is set at about pF 6 by contamination from distilled water, reagents etc.

Urinary Fluoride Concentration in 6- to 9-Year-Old Children Drinking Water with a Very Low Fluoride Level

Midmorning urine samples were collected from 623 first- and second-grade children in four elementary schools. The mean for water F content in the residential area from which the population was drawn w

Inverse relationship between fluoride and cancer in mouth and throat?

For all the 121 municipalities in Southern Norway where 60% or more of the inhabitants get water from registered water supplies, the municipal average concentration of natural fluoride in the water has been determined and the municipalities divided into three groups with fluoride level 0--0.05 mg/1, 0.06--0.10 mg/1, and 0.11--0.50 mg/1, respectively. The average, age-adjusted municipal mortality rate of cancer in the mouth and throat was then determined for each of these groups by sex. The resulting figures show that the mortality rate declines for both sexes with increasing fluoride level: For males from 4.7 deaths per 100 000 per year on the low fluoride level, to 3.9 deaths per 100 000 per year on the medium fluoride level, and to 3.1 deaths per 100 000 per year on the high fluoride level. For females the corresponding figures are 1.5, 1.3 and 0.5. Arguments to show that these figures are unbiased from different tobacco consumption habits, differences between urban and rural municipalities, and differences in population size are presented. Possible, explicatory models are discussed.

Distribution of trace metals during oil shale retorting

Three samples of raw oil shale from the Green River formation of western Colorado were retorted under conditions simulating the Tosco II process, a potentially commercial process. The raw shales and all resulting retort products were analyzed for various trace metals in an attempt to ascertain migratory patterns and resulting distributions through the retort so that effective environmental control measures could be implemented if necessary. Some evidence of low-level fluoride, boron, and copper partitioning to the water fraction was found. Similar behavior of arsenic and zinc partitioning to the shale oil product was observed with the ramainder of the metals investigated predominantly retained in the spent fly ash. 20 references, tables.

21—THE HYDROLYSIS OF FLUOROZIRCONATE ON WOOL

An investigation is reported in which the extensive loss of fluoride on the laundering of fluorozirconate-treated wool is confirmed by using a pyrohydrolysis-analysis method. Fluoride is not necessary for adequate flame-retardance, but, at low fluoride levels (i.e., F/Zr ratio less than 2), the formation of a complex between zirconium and the carboxyl groups of wool is necessary. The burning behaviour of an esterified fluorozirconate-treated sample is adversely affected as fluoride is lost because a carboxyl complex cannot be formed. Zirconium dioxide itself is ineffective as a flame-retardant for wool.

Permeability and fluoride release of lining materials containing amine fluorides.

The addition of amine fluorides to a copal recin (Copalite) and a chlorine caoutchouc varnish (Pergut S-40) has been studied. The permeability of Copalite films was only slightly increased whereas the excellent film-forming qualities of Pergut S-40 were destroyed by the addition of fluorides. A high fluoride release was found initially from test films of the materials but within 2-3 weeks a decrease to very low fluoride levels was observed.