Human health fluoride effects

Fluoride is one of the chemical contaminants that must be considered, because high fluoride levels in drinking-water are a major source of adverse human health effects in some parts of the world,... 

TABLE 8.5.3 Predicted Effects on Human Health of Exposure to Various Concentrations of Hydrogen Fluoride ... 

Fluorine is available to humans, plants and animals mainly in the form of fluoride ion (F ). Body fluoride status depends on numerous factors, including the total amount of fluoride ingested daily, its bioavailability and metabolism. The adequate intake (Al) of fluoride from all sources is set by the Standing Committee on the Scientific Evaluation of the Dietary Reference Intakes at 0.05 mg/day/kg body weight this intake is recommended for all ages above 6 months, because it confers a high level of protection against dental caries and is not associated with any known unwanted health effects [8]. 

Fluoride has certain physiological properties [31,32] of great importance to human health. The role of fluoride in the process of mineralization of certain tissues is important. At low concentrations fluoride stabilizes the skeletal system by increasing the size of apatite crystals and reducing their solubility [12]. Although beneficial effects can be demonstrated at low concentrations, it has detrimental effects when concentrations exceed the threshold [33],... 

More than 15 additional trace elements are considered by some investigators to have a potentially important role in human medicine. A review by Nielsen considers these in detail and discusses emerging concepts of essentiality. For some such as lead, cadmium, arsenic, aluminum, and nickel, the clinical laboratory will primarily consider them as toxic elements (see Chapter 35). Others, such as lithium and fluoride, are classified as pharmacologically beneficial and monitoring of dosage may be required. Some elements can be considered nutritionally beneficial and are reported to produce restorative health effects at lower dosages. Evidence comes mainly from animal studies when dietary depletion of the element is combined with other metabohc, hormonal, or physiological stressors. ... 

As discussed within this symposium, it is not possible to keep all chemicals out of groundwater. As limits of detection are reduced more chemicals will be detected. Clearly there are many different chemicals in our potable water. Some are intentionally introduced, such as chlorine or fluoride salts some are natural products some are unintentionally present, such as pathogens, industrial chemicals, pharmaceuticals, and pesticides and some are synthesized in situ, such as chloroform. Although clear documentation of adverse effects is not common, epidemiological implications of water quality effects have been reported [12]. The present paper will address questions concerning the safety of pesticides in groundwater from the perspective of human health. 

Sodium fluoride (SO-dee-um FLOR-ide) is a colorless to white crystalline solid or powder. It is best known for its role in efforts to prevent tooth decay. It may he added to toothpastes or mouthwashes or to municipal water supplies for this purpose. Although the practice of fluoridating water is now widespread in the United States, it remains the subject of controversy regarding its potential health effects on humans. 

In fact, the presence of such inorganic arsenic (As(V/III)), fluoride (F ) and uranium (U(VI)) species (mostly ions) in groundwater (and to less extent in surface water) is a critical global issue, and has created severe health impacts for decades. Bioaccumulation and adverse effects on human health by intake of these ions via drinking water have been well documented (e.g., Fawell et al., 2006 Qrloff et al., 2004 Smedley and Kinniburgh, 2002). 

An excess amount of fluoride anions in drinking water has been known to cause adverse effects on human health. To prevent these harmful consequences, especially problems resulting from fluorosis, the World Health Organization (WHO) fixed the maximum acceptable concentration of fluoride anions in drinking water to 1.5 mg/L (Essadki et al., 2009). 

Health and Safety Factors. Boron trifluoride is primarily a pulmonary irritant. The toxicity of the gas to humans has not been reported (58), but laboratory tests on animals gave results ranging from an increased pneumonitis to death. The TLV is 1 ppm (59,60). Inhalation toxicity studies in rats have shown that exposure to BF at 17 mg/m resulted in renal toxicity, whereas exposure at 6 mg/m did not result in a toxic response (61). Prolonged inhalation produced dental fluorosis (62). High concentrations bum the skin similarly to acids such as HBF and, if the skin is subject to prolonged exposure, the treatment should be the same as for fluoride exposure and hypocalcemia. No chronic effects have been observed in workers exposed to small quantities of the gas at frequent intervals over a period of years. 

This paper is written with the aim of providing sufficient background to help understand the mechanism of action of fluoride ion on humans. The main focus is on the effects of fluoride on dental health, in-depth discussion of skeletal fluorosis and use of fluoride for treating osteoporosis being outside the scope of this paper. Current information on the main sources of human exposure to fluoride and current recommendations for adequate intake (Al) of fluoride, as well as methods for assessing exposure, will be reviewed. 

Stannous fluoride is a classic example of a compound that must be used in moderation. In small concentrations, it appears to be completely safe for human uses. In larger doses, it may have some health risks. For example, in concentrations of more than two parts per million, stannous fluoride (and other fluorides) may causes fluorosis, a mottling (brownish coloring) of the teeth and changes in bone composition. Individuals who work with pure stannous fluoride may also be at risk from exposure to its powder or dust. It is an irritant and may cause inflammation of the skin, eyes, or respiratory system. Symptoms may include coughing, wheezing, and shortness of breath. These effects do not occur, however, at the level at which stannous fluoride occurs in tooth care products. 

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