RESUMEN
The biological effects of fluoride were investigated on rats fed pure spring water (natural F- concentration=0.2 ppm) or spring water enriched with NaF to result 0.8, 1.1 or 2.2 ppm F- during 180 days. The main effects of fluoride have been: 1. electrocardiographic recordings showed a significant reduction of the electrical systole (QTc). 2. body weight gain was unaffected by the treatment. 3. bivalent cations (Ca²+, Mg²+ and Zn²+) were importantly reduced in adrenals, ventricular myocardium, and bone. 4. Na+ concentration was strikingly increased in aorta, lung and joint of treated animals. 5. in testis, we observed Ca²+ and Na+ retention. 6. Zinc ions were depleted in most tissues, except kidney and submandibular salivary gland. Our results revealed that chronic administration of fluoridated water does influence systemic biochemical homeostasis in rats, without evoking any overt sign of fluorosis. Moreover, the definition of a "safe" concentration of F- in public water must consider that the dosis at which beneficial effects as caries reduction are attained is not far away from that one which causes chronic yet subclinical toxic effects