Abstract

Rats given 4 mg. fluoride/kg./day for eight days excreted more calcium and phosphorus and retained less than the controls. In bone ash from rats given different fluoride doses for 40 days the calcium and phosphorus were maximal after a total dose of about 250 μg. fluoride/rat, but fell to subnormal levels after higher doses. The calcium and phosphorus levels in bone ash from rats given 750 μg. fluoride/day fell with the duration of treatment.

Rats exposed to 9·4-11·7 μg. hydrogen fluoride/litre air absorbed fluoride rapidly, as shown by increased urinary excretion, by changes in the enamel of the teeth, and by rising fluoride levels in the teeth and bones. Radiological examination, however, showed no gross changes. Urinary excretion increased with exposure time.