Abstract
The minimal dose capable of producing chronic intoxication in the albino rat has been determined for sodium fluoride, sodium fluosilicate, barium fluosilicate, and sodium aluminum fluoride (natural cryolite). Male rats ranging in weight from 30 to 60 gm. were placed on a basic diet consisting of corn meal 73 gm., linseed oil cake meal 10 gm., alfalfa 2 gm., casein 10 gm., codliver oil 3 gm., bone ash 1 1/2 gm., sodium chloride 1/2 gm. For each compound studied 6 control rats were placed on this diet, and for each dosage level 6 rats were placed on the same diet to which a weighed amount of the fluorine compound had been added and evenly distributed by means of a mechanical mixer. Analyses showed even distribution of the toxic agent throughout the basic diet. For each compound a series of dosage levels was employed, each dose being one-half the preceding dose.
The criterion of toxic action was bleaching of the upper and lower, especially the lower, incisor teeth. Table I summarizes the data. In the case of each compound, the dosage level indicated means that bleaching was present in all of the rats on that dosage, but absent when one-half of that dose was administered.
When the fluorine content of the molecule is taken into consideration it is seen that despite a marked variation in water solubility the chronic toxicity of the compounds, expressed as parts of fluorine per million parts of food, is remarkably constant. For all practical purposes, it may be stated that in the compounds studied fluorine is capable of producing chronic intoxication, as indicated by bleaching of the rat incisors, in concentrations as low as 14 to 16 parts per million regardless of the solubility of the compound containing the fluorine. Depending upon the amount of food consumed by the albino rat, this means that from one-half to 1 mg. of fluorine per day per kilo of body weight is capable of producing definite signs of injury to the rat incisors.
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