pH and the cytotoxicity of fluoride in an animal cell culture system.

To investigate the mechanism for the toxicity of silicate cement as observed in a cell culture system, the effects of pH and fluoride were tested on human epithelial cells (NCTC 2544). At pH 7.3, fluoride concentrations from 15 to 25 mug/ml (0.79 to 1.3 mM) had a growth inhibitory effect. When pH of the incubation medium was lowered in the range 7.0 to 6.4, an enhanced cytoxic effect of fluoride was found, and even at 5 to 10 mug/ml growth inhibition occurred. Concomitant with the enhanced cytotoxicity of fluoride at low pH, there was an increased utilization of glucose and formation of lactate. Upon lowering the pH of the incubation medium from 7.4 to 6.7 a twofold increase in the intracellular concentration of fluoride was found.