10,326
edits
Changes
Jump to navigation
Jump to search
Line 235:
Line 235: − + + + + + + + + + + + + + +
→Toxicity effects of excess fluoride
Fluoride (F-), the ionic form of fluorine, can stimulate bone formation and it also has been demonstrated to reduce dental caries at doses of at least 0.7 mg/l in drinking water (Selinus et al, 2013). Concentration in the excess of this figure leads to adverse health effects called fluorosis (Table 4). Dental fluorosis occurs when the fluoride ions continually substitute for hydroxyl ions in the apatite [Ca10 (PO4)6(OH, F, Cl, Br)2] crystals of the enamel. The enamel loses its glittering appearance as chalky white patches develop; this is called mottled enamel (Schamschula and Barmes, 1981). Dental fluorosis proceeds to change the colour of the teeth from chalky white to yellow, brown or black. Finally, the yellow, brown or black patches become dissolved ([[:File:UNN_Medical_Geology_Fig_7.png|Figure 7]]).
Fluoride (F-), the ionic form of fluorine, can stimulate bone formation and it also has been demonstrated to reduce dental caries at doses of at least 0.7 mg/l in drinking water (Selinus et al, 2013). Concentration in the excess of this figure leads to adverse health effects called fluorosis (Table 4). Dental fluorosis occurs when the fluoride ions continually substitute for hydroxyl ions in the apatite [Ca10 (PO4)6(OH, F, Cl, Br)2] crystals of the enamel. The enamel loses its glittering appearance as chalky white patches develop; this is called mottled enamel (Schamschula and Barmes, 1981). Dental fluorosis proceeds to change the colour of the teeth from chalky white to yellow, brown or black. Finally, the yellow, brown or black patches become dissolved ([[:File:UNN_Medical_Geology_Fig_7.png|Figure 7]]).
[[TABLE 4]]
{| class="wikitable"
|-
|+ Table 4: Possible Health Effects of Different Fluoride Concentrations in Drinking Water (Davies, 2010).
|-
! Concentration of Fluoride (mg/l) || Possible Health Effects
|-
| Less than 0.5 ||Possibility of dental cavities
|-
| 0.5–1.5 || Normal concentration
|-
| Greater than 1.5 || Possibility of mottling of teeth and dental fluorosis
|-
| Greater than 3 || Occurrence of skeletal fluorosis (e.g. osteoarthritis, [[:File:UNN_Medical_Geology_Fig_7.png|Figure 7]])
|}
Geologic materials that are characteristically rich in fluorine are organic clays and shales, carbonatites, phosphates, hydrothermal ores and silicic igneous rocks such as rhyolites, dacites and granites (Selinus et al, 2010).
Geologic materials that are characteristically rich in fluorine are organic clays and shales, carbonatites, phosphates, hydrothermal ores and silicic igneous rocks such as rhyolites, dacites and granites (Selinus et al, 2010).