A STUDY OF THE RELATIVE TOXICITY OF SODIUM FLUORIDE IN A DRY DIET, IN MILK, AND IN WATER

¹ Department of Foods and Nutrition, Purdue University, Lafayette, Indiana

A study has been made of the effects of feeding albino rats like concentrations of sodium fluoride incorporated in a dry diet, in evaporated milk, and in water.

The results indicate an increasing toxicity from the first to the last. The toxicity of a 0.05 per cent concentration in water was so great that most of the rats died in from a few days to two weeks of time. The rats were able to survive on the fluoride-containing milk diet, but the growth rate was markedly depressed. There was a lesser depression of the growth rate with 0.05 per cent sodium fluoride incorporated in the dry diet.

The actual amount of sodium fluoride ingested in the milk diet was somewhat higher than in the dry diet, but apparently this does not account altogether for the difference in toxicity, since in a previous study a fluoride intake in a dry diet exceeding that in the milk affected growth less adversely.

Dental signs of fluorosis occurred in all three groups but appeared earliest in the few surviving rats receiving the sodium fluoride in the water.

The findings with respect to the toxicity of sodium fluoride in milk may have significance in relation to the possibility that the fluoride content of milk produced in certain regions may be sufficient to play a part in the occurrence of dental fluorosis in young children for whom milk constitutes the major part of the diet.