Chemistry and Bioavailability Aspects of Fluoride in Drinking Water


1. Hexafluorosilicate added to fluoridate water is effectively 100% dissociated to form fluoride ion under water treatment conditions. Therefore in terms of chemistry and bioavailability there is absolutely no difference between added and “natural” fluoride.

2. The effect of major cations – calcium and magnesium (hardness) and sodium – on the chemical speciation and hence bioavailability of fluoride is very small.

3. Fluoride forms strong complexes with aluminium so effects on bioavailability are possible. Animal studies suggest that the presence of fluoride may increase the bioavailability of aluminium and that aluminium may decrease the availability of fluoride. However this is based on limited evidence from studies that employed much higher concentrations of aluminium and fluoride than would be present in drinking water.

4. The presence of fluoride at a concentration on 1 mg/l will have practically no effect on the chemical speciation and bioavailability of iron, copper or lead.

5. At a concentration of 1 mg/l as F, fluoride could not cause significant interactions between other chemical species in drinking water. Fluoride at a concentration of 1 mg/l will have negligible impact on corrosivity of water towards the distribution system.

6. The quantities of trace metals impurities added as a result of fluoridation are very small and would have no discernible impact on “toxicity” of drinking water.

NSF Report No.: CO 5037 July 2002 Authors: P J Jackson, P W Harvey and W F Young Contract Manager: M Hosford Contract No.: 09607-7

Read Full Study