The authors, in order to study histologically the effect on the liver and kidneys of salt-fluor, have administred NaF orally to eighty rats, at the dosage of 0.02 mg % per kg of weight. The animals were decapitated on the 180th day of the experiment.
The histological test of the kidneys revealed, in 45 per cent of the treated animals, some alterations at the expense of the tubular epithelium whose cells showed signs of having been affected by the salt-fluor to the point of necrosis, with occlusion in some cases of tubular lumen.
As regards the liver, the authors observed in 35 per cent of the rats submitted to treatment, slight cellular alterations, whereas the shape of the liver appeared generally well preserved.
On the whole the renal alterations were not important; nevertheless, though admitting the not perfect correspondence of what is to be seen in experimental animals with what presumably happens in man, the authors think that the experimental control of a drug like fluor, supplied to a whole population through the fluoration of drinking waters, must furnish unmistakable data in so far as no difference has been noticed between the control and experimental groups. The authors, therefore, conclude by stating the need of further biological controls demonstrating also the actual harmlessness of fluor in prophylactic doses for decayed teeth.