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CAN FLUORIDATION AFFECT WATER LEAD (II) LEVELS AND LEAD (II) NEUROTOXICITY?
Citation:
Urbansky*, E T. AND M R. Schock*. CAN FLUORIDATION AFFECT WATER LEAD (II) LEVELS AND LEAD (II) NEUROTOXICITY? Presented at American Water Works Association Annual Conference, Denver, CO, 6/11-15/2000.
Description:
Recent reports have attempted to show that certain approaches to fluoridating potable water is linked to increased levels of lead(II) in the blood. We examine these claims in light of the established science and critically evaluate their significance. The completeness of hexafluorosilicate hydrolysis is of paramount importance in ensuring that total water quality is maintained. The possible impacts of such complexes as PbII-F-SiF5 or PbF(2-x) are discussed as are the contributions of fluoridation byproducts to total acid content. We caluclate the fractional distribution of aqueou species based on known chemical equilibria and show the species concentrations for a selected model tap water with a composition that would favor lead fluoride and silicofluoride complexation. We discuss and quantitatively show the effects of other complexing anions, such as carbonate or hydroxide. Overall, we conclude that no credible evidence exists to show that water fluoridation has any quantifiable effects on the solubility, bioavailability, bioaccumulation, or reactivity of lead(O) or lead(II) compounds. The governing factors are the concentrations of a number of other species, such as (bi)carbnonate, hydroxide, or chloride, whose effects far exceed those of fluoride or fluorosilicates under drinking water conditiions. Lastly, we consider some previous epidemiological studies of lead(II) exposure and how recent papers fare methodologically.