Influence of Inorganic Ions on Fluoride Retention in the Rat. ∗

Abstract

Summary

1) The whole carcass retention of fluoride by rats receiving a fluoride drinking water containing a combination of Ca⁺⁺, Mg⁺⁺, Fe⁺⁺, and PO₄— ions was significantly less than in rats drinking a chemically pure fluoride water containing no additional inorganic ions. 2) In contrast, studies of the individual ions at various concentrations show only small fluctuations in the proportion retained. No significant influence on retention was noted when any of the ions were studied singly. 3) The decrease in retention seen in rats ingesting the water containing a combination of ions suggests that the influence of the ions may be additive or synergistic. This may be important since most natural waters contain a group of several inorganic constituents. More attention should be placed on inorganic composition of the communal water supplies before fortifying them with fluoride. It is possible that if the combination of major inorganic constituents of natural waters exceeds a yet-to-be determined concentration, optimal fluoride concentration would need to differ from the now accepted level of 1 ppm in order to produce maximum anticariogenic benefits.