Abstract
The effects of calcium ion and broad pH ranges on free fluoride ion aqueous concentrations were measured directly and computed theoretically. Solubility calculations indicate that blood fluoride concentrations that occur in lethal poisonings would decrease calcium below prevailing levels. Acute lethal poisoning and also many of the chronic effects of fluoride involve alterations in the chemical activity of calcium by the fluoride ion. Natural calcium fluoride with low solubility and toxicity from ingestion is distinct from fully soluble toxic industrial fluorides. The toxicity of fluoride is determined by environmental conditions and the positive cations present. At a pH typical of gastric juice, fluoride is largely protonated as hydrofluoric acid HF. Industrial fluoride ingested from treated water enters saliva at levels too low to affect dental caries. Blood levels during lifelong consumption can harm heart, bone, brain, and even developing teeth enamel. The widespread policy known as water fluoridation is discussed in light of these findings
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Environmental and physiological factors affecting dental fluorosis
In addition to differences in fluoride intake and possibly to calcium deficiency or malnutrition, there are several factors which may account for individual differences in the occurrence of dental fluorosis. Disorders in acid-base balance affect the renal handling of fluoride such that, in acidosis, the excretion rate is diminished and,
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Effects of plasma fluoride and dietary calcium concentrations on GI absorption and secretion of fluoride in the rat
This 30-day balance study with weanling rats was designed to determine the effects of plasma fluoride and dietary calcium concentration and their interaction on the absorption, balance, and tissue concentrations of fluoride. The three major groups differed according to the total exposure and plasma concentrations of fluoride. One group received
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Efficacy of Calcium-Containing Eggshell Powder Supplementation on Urinary Fluoride and Fluorosis Symptoms in Women in the Ethiopian Rift Valley.
Dietary calcium binds Fluoride (F), thus preventing excess F absorption. We aimed to assess the efficacy of supplementing calcium-containing Eggshell Powder (ESP) on F absorption using urine F excretion and on fluorosis symptoms. In total, 82 women (41 Intervention Group, IG; 41 Control Group, CG) were recruited; overall, 39 in
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Fluoride metabolism
Knowledge of all aspects of fluoride metabolism is essential for comprehending the biological effects of this ion in humans as well as to drive the prevention (and treatment) of fluoride toxicity. Several aspects of fluoride metabolism - including gastric absorption, distribution and renal excretion - are pH-dependent because the coefficient
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Modulation of fluoride toxicity in rats by calcium carbonate and by withdrawal of fluoride exposure.
In order to assess the effect of calcium on the toxic effects of fluoride, adult female Wistar rats were treated with sodium fluoride (NaF, 500 ppm in drinking water) alone or in combination with calcium carbonate (CaCO3, 50 mg/kg by oral intubation) daily for 60 days. Food, water and fluoride
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Nutrient Deficiencies Enhance Fluoride Toxicity
It has been known since the 1930s that poor nutrition enhances the toxicity of fluoride. As discussed below, nutrient deficiencies have been specifically linked to increased susceptibility to fluoride-induced tooth damage (dental fluorosis), bone damage (osteomalacia), neurotoxicity (reduced intelligence), and mutagenicity. The nutrients of primary importance appear to be calcium,
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Factors which increase the risk for skeletal fluorosis
The risk for developing skeletal fluorosis, and the course the disease will take, is not solely dependent on the dose of fluoride ingested. Indeed, people exposed to similar doses of fluoride may experience markedly different effects. While the wide range in individual response to fluoride is not yet fully understood, the following are some of the factors that are believed to play a role.
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Fluoride Exposure Aggravates the Impact of Iodine Deficiency
A consistent body of animal and human research shows that fluoride exposure worsens the impact of an iodine deficiency. Iodine is the basic building block of the T3 and T4 hormones and thus an adequate iodine intake is essential for the proper functioning of the thyroid gland. When iodine intake is inadequate during infancy and
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Skeletal Fluorosis & Individual Variability
One of the common fallacies in the research on skeletal fluorosis is the notion that there is a uniform level of fluoride that is safe for everyone in the population. These "safety thresholds" have been expressed in terms of (a) bone fluoride content, (b) daily dose, (c) water fluoride level, (d) urinary fluoride level, and (e) blood fluoride level. The central fallacy with each of these alleged safety thresholds, however, is that they ignore the wide range of individual susceptibility in how people respond to toxic substances, including fluoride.
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Fluorine recovery in the fertilizer industry - a review.
The fluorine compounds liberated during the acidulation of phosphate rock in the manufacture of phosphoric acid and fertilizers are now rightly regarded as a menace, and the industry is now obliged to suppress emissions of fluorine-containing vapours to within very low limits in most parts of the world. As with any pollution control operation, it is highly desirable for the operator of the fluorine scrubbing operation to find a use or market for the recovered fluorine to help defray at least partially the cost of the operation.
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