[Genotoxic activity test of sodium fluoride in vitro].

Abstract

The artificial drinking water fluoridization provided as a mass preventive measure against dental decay poses another substantial problem which is a possibility of genotoxic action. Up to this date, this matter remains still obscur and is discussed with more or less intensity from time to time. The mentioned fact supported authors to study the impact of short-term 24 hrs sodium fluoride (NaF) action in concentration range of 0-500 mg.1(-1) drinking water in the frame of so-called minimal testing set (analysis of chromosomal aberrations in human peripheral lymphocytes, Ames test). For the initial NaF concentration applied, the reference value of 1 mg per 1 liter artificial fluoridization was estimated. The use of Ames test with TA 98 and TA 100 Salmonella typhimurium (+/- S9) strains showed no significant increase in revertants responsible of NaF mutagenic activity in any of applied concentrations (0-1300 mg per 1 Petri dish; = 0-520 mg.l-1 converted to the basic supplementative dose). Cytogenetic analysis of peripheral lymphocytes showed more sensitivity than prototrofic salmonella test. Yet one order higher NaF concentration than its application norm 1 mg.l-1 (i.e. 11 mg.l-1) has induced the occurrence of 3.8% ABB after single addition for 24 hrs to the "healthy" blood cultivated in vitro at short-term. This accounts for a value close to the level of statistically significant difference with regard to the application norm recommended. This level has been even exceeded as for a total count of fragments and exchanged parts. Thus the two orders higher NaF concentration (110.0 mg.l-1) resulted in a strong increase of cells with chromosomal aberrations for all of indicators observed; e.g. 27.5% ABB. Based on literary sources, obtained results and properly experience in practical proceeding artificial fluoridation, the authors concluded that the latter is not adequate to the up-to-date status of knowledge. Besides of economical and technical problems, those scientific are mainly concerned with making doubtful the auto-presumed genotoxic inertness for chronic users of fluoridated drinking water. Author's opinion is that when necessarily provided, the artificial fluoridization of drinking water should be proceeded selectively (in accord with real requirements of an appropriated population group, its age structure and location), temporarily and with intermittent checkout of fluoridization application regimen. To conclude, authors recommend further observation with use of biological model situations in vivo.