THE GENOTOXIC AND CYTOTOXIC ACTIVITIES OF INORGANIC FLUORIDE IN CULTURED RAT BONE-MARROW CELLS

The effects of sodium and potassium fluoride (NaF and KF) at concentra tions ranging from 10(-7) to 10(-2) M for 12, 24, or 36 h on cultured rat bone marrow cells have been studied with respect to cytotoxicity a nd induction of sister-chromatid exchanges (SCE). At the three exposur e times, cell survival progressively decreased with increasing concent rations. Treatment with 10(-2) M fluoride resulted in a statistically significant death (62-65%) of cells. Similarly, no dividing cells were encountered at concentrations of 10(-3) M and 10(-2) M, and significa nt reductions in mitotic index (MI) were calculated at 10(-4) M. In co ntrast, cell kinetics, expressed as cell proliferation index (CPI), re vealed no significant inhibitory effect of fluoride on cell proliferat ion. Furthermore, the mean SCE score reached a maximum (7.64 SCE/cell) in the 24-h-treated cultures. This value was not significantly differ ent from that observed in sodium chloride (NaCl) at 10(-2) M (5.42 SCE /cell) and distilled water (4.86 SCE/cell) controls. In comparison, mi tomycin-C (MMC, positive control) at 5 X 10(-8) M caused an average of 22.13 SCE/cell. These results indicated an inhibition of cell divisio n and death of cells with high doses of fluoride with no effect on SCE frequencies.