Cumulative exposure to fluoride is important.
Aobo, T., and Fejerskov, O. Dental fluorosis: chemistry and biology. Crit Rev Oral Biol Med. 2002;13(2):155-70.
This review aims at discussing the pathogenesis of enamel fluorosis in relation to a putative linkage among ameloblastic activities, secreted enamel matrix proteins and multiple proteases, growing enamel crystals, and fluid composition, including calcium and fluoride ions. Fluoride is the most important caries-preventive agent in dentistry. In the last two decades, increasing fluoride exposure in various forms and vehicles is most likely the explanation for an increase in the prevalence of mild-to-moderate forms of dental fluorosis in many communities, not the least in those in which controlled water fluoridation has been established. The effects of fluoride on enamel formation causing dental fluorosis in man are cumulative, rather than requiring a specific threshold dose, depending on the total fluoride intake from all sources and the duration of fluoride exposure. Enamel mineralization is highly sensitive to free fluoride ions, which uniquely promote the hydrolysis of acidic precursors such as octacalcium phosphate and precipitation of fluoridated apatite crystals. Once fluoride is incorporated into enamel crystals, the ion likely affects the subsequent mineralization process by reducing the solubility of the mineral and thereby modulating the ionic composition in the fluid surrounding the mineral. In the light of evidence obtained in human and animal studies, it is now most likely that enamel hypomineralization in fluorotic teeth is due predominantly to the aberrant effects of excess fluoride on the rates at which matrix proteins break down and/or the rates at which the by-products from this degradation are withdrawn from the maturing enamel. Any interference with enamel matrix removal could yield retarding effects on the accompanying crystal growth through the maturation stages, resulting in different magnitudes of enamel porosity at the time of tooth eruption. Currently, there is no direct proof that fluoride at micromolar levels affects proliferation and differentiation of enamel organ cells. Fluoride does not seem to affect the production and secretion of enamel matrix proteins and proteases within the dose range causing dental fluorosis in man. Most likely, the fluoride uptake interferes, indirectly, with the protease activities by decreasing free Ca(2+) concentration in the mineralizing milieu. The Ca(2+)-mediated regulation of protease activities is consistent with the in situ observations that (a) enzymatic cleavages of the amelogenins take place only at slow rates through the secretory phase with the limited calcium transport and that, (b) under normal amelogenesis, the amelogenin degradation appears to be accelerated during the transitional and early maturation stages with the increased calcium transport. Since the predominant cariostatic effect of fluoride is not due to its uptake by the enamel during tooth development, it is possible to obtain extensive caries reduction without a concomitant risk of dental fluorosis. Further efforts and research are needed to settle the currently uncertain issues, e.g., the incidence, prevalence, and causes of dental or skeletal fluorosis in relation to all sources of fluoride and the appropriate dose levels and timing of fluoride exposure for prevention and control of dental fluorosis and caries.
Posted in Fluoride
Li, L. The biochemistry and physiology of metallic fluoride: action, mechanism, and implications. Crit Rev Oral Biol Med. 2003;14(2):100-14.
Fluoride is a well-known G protein activator. Activation of heterotrimeric GTP-binding proteins by fluoride requires trace amounts of Al3+ or Be2+ ions. AlFx mimics a gamma-phosphate at its transition state in a Galpha protein and is therefore able to inhibit its GTPase activity. AlFx also forms complexes with small GTP-binding proteins in the presence of their GTPase-activating proteins (GAP). As phosphate analogs, AlFx or BeFx affect the activity of a variety of phosphoryl transfer enzymes. Most of these enzymes are fundamentally important in cell signal transduction or energy metabolism. Al3+ and F- tend to form stable complexes in aqueous solution. The exact structure and concentration of AlFx depend on the pH and the amount of F- and Al3+ in the solution. Humans are exposed to both F and Al. It is possible that Al-F complexes may be formed in vivo, or formed in vitro prior to their intake by humans. Al-F complexes may play physiological or pathological roles in bone biology, fluorosis, neurotoxicity, and oral diseases such as dental caries and periodontal disease. The aim of this review is to discuss the basic chemical, biochemical, and toxicological properties of metallic fluoride, to explore its potential physiological and clinical implications.
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Rocha-Amador, D., Navarro, M.E., Carrizales, L., Morales, R., and Calderon, J. Decreased intelligence in children and exposure to fluoride and arsenic in drinking water. Cad Saude Publica. 2007;23 Suppl 4:S579-87.
Recent evidence suggests that fluoride (F) and arsenic (As) may adversely affect intelligence quotient (IQ) scores. We explore the association between exposure to F and As in drinking water and intelligence in children. Three rural communities in Mexico with contrasting levels of F and As in drinking water were studied: Moctezuma (F 0.8+/-1.4 mg/L; As 5.8+/-1.3 microg/L); Salitral (F 5.3+/-0.9 mg/L; As 169+/-0.9 microg/L) and 5 de Febrero (F 9.4+/-0.9 mg/L; As 194+/-1.3 microg/L). The final study sample consisted of 132 children from 6 to 10 years old. After controlling for confounders, an inverse association was observed between F in urine and Performance, Verbal, and Full IQ scores (beta values = -13, -15.6, -16.9, respectively). Similar results were observed for F in drinking water (beta values = -6.7, -11.2, -10.2, respectively) and As in drinking water (beta values= -4.30, -6.40, -6.15, respectively). The p-values for all cases were < 0.001. A significant association was observed between As in urine and Full IQ scores (beta = -5.72, p = 0.003). These data suggest that children exposed to either F or As have increased risks of reduced IQ scores.
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Posted in Fluoride
The State of Illinois is giving awards to their communities who add fluoride to drinking water. Science is out…..platitudes are in. Will the state notify those citizens who will be adversely impacted by their water system adding fluoride? There are always risks, even if small…
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Opposition to fluoridation is not going to go away, as citizens become more informed about the science…..
Posted in Fluoride
Consider this report and decide. Would you drinking water in Venezuela, or any other commuist country? Do you think the environment is really betther?
Those of you who think the US Constitutional government is so bad, just go see what its like in Venezuela….we will probably never know for sure.
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Ibekwe, A.M., Murinda, S.E., and Graves, A.K. Microbiological evaluation of water quality from urban watersheds for domestic water supply improvement. Int J Environ Res Public Health. 2011 Dec;8(12):4460-76. Epub 2011 Nov 30.
Abstract: Agricultural and urban runoffs may be major sources of pollution of water bodies and major sources of bacteria affecting the quality of drinking water. Of the different pathways by which bacterial pathogens can enter drinking water, this one has received little attention to date; that is, because soils are often considered to be near perfect filters for the transport of bacterial pathogens through the subsoil to groundwater. The goals of this study were to determine the distribution, diversity, and antimicrobial resistance of pathogenic Escherichia coli isolates from low flowing river water and sediment with inputs from different sources before water is discharged into ground water and to compare microbial contamination in water and sediment at different sampling sites. Water and sediment samples were collected from 19 locations throughout the watershed for the isolation of pathogenic E. coli. Heterotrophic plate counts and E. coli were also determined after running tertiary treated water through two tanks containing aquifer sand material. Presumptive pathogenic E. coli isolates were obtained and characterized for virulent factors and antimicrobial resistance. None of the isolates was confirmed as Shiga toxin E. coli (STEC), but as others, such as enterotoxigenic E. coli (ETEC). Pulsed field gel electrophoresis (PFGE) was used to show the diversity E. coli populations from different sources throughout the watershed. Seventy six percent of the isolates from urban sources exhibited resistance to more than one antimicrobial agent. A subsequent filtration experiment after water has gone through filtration tanks containing aquifer sand material showed that there was a 1 to 2 log reduction in E. coli in aquifer sand tank. Our data showed multiple strains of E. coli without virulence attributes, but with high distribution of resistant phenotypes. Therefore, the occurrence of E. coli with multiple resistances in the environment is a matter of great concern due to possible transfer of resistant genes from nonpathogenic to pathogenic strains that may result in increased duration and severity of morbidity.
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Diouf, M., Cisse, D., Lo, C.M., Ly, M., Faye, D., and Ndiaye, O. [Pregnant women living in areas of endemic fluorosis in Senegal and low birthweight newborns: Case-control study.] Rev Epidemiol Sante Publique. 2012 Mar 14. [Article in French]
Département d’odontologie, faculté de médecine de pharmacie et d’odontologie, université Cheikh Anta Diop de Dakar, BP 45391, Dakar, Fann, Sénégal.
BACKGROUND: In developing countries, maternal and neonatal mortality is high. Among the causes of death during the neonatal period, low birth weight is crucial. A dose of fluoride beyond 2 mg/L causes enamel damage, possibly affecting the fetus. The aim of this study was to search for an association between dental fluorosis in the mother and low birthweight of the newborn.
METHODOLOGY: This was a case-control study performed in an endemic area in Senegal (Diourbel). It included 108 mothers who gave birth to newborns weighing less than 2500g (cases) and 216 mothers with newborns weighing greater or equal to 2500g (controls). Data on socio-demographic, lifestyle, history and pregnancy variables were collected. Those related to water consumption during pregnancy and dental fluorosis (Dean’s index) were measured. The data were analyzed by R software. Logistic regression was used to identify associations and the statistical significance level was set to 0.05.
RESULTS: The proportions of mothers consuming well water were 62% among cases versus 43.5% among controls. The score 4 of Dean’s Index was reported for 25.9% of cases versus 6.9% of controls. The water consumed and the modal score of Dean’s Index were significantly associated with the occurrence of low birthweight adjusted for gender, consanguinity, anemia and hypertension.
CONCLUSION: Low birthweight was associated with pregnant women living in endemic areas. Defluoridation programs and access for pregnant women and children to high quality water are necessary in areas of endemic fluorosis.
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