Skeletal metabolism and bone mineral density in fluoride-exposed rats

As part of a two-stage investigation, adult male Wistar rats were exposed t o above-normal fluoride intake for 6 months: a) to HF by inhalation for 2 h r/day at a concentration of 8.7 +/- 5.7 mg/m(3) and b) to NaF in drinking w ater containing 20 mg F-/L. The fluoride content in urine, vertebrae L-2 - L-4, tibia, and incisors was significantly increased in the exposed animals . More fluoride was excreted in urine by animals exposed by the inhalatory than by the oral route. Bones of control and exposed animals were of simila r mechanical resistance. No differences in bone mineral density (BMD) were found between exposed and control animals. Moreover, no significant differe nces were found in alkaline phosphatase activity, calcium and magnesium con centration in serum, and hydroxyproline concentration in urine between cont rol and exposed animals. The results indicate that even a threefold increas e in bone fluoride does not cause a distinct change in metabolism, mineral density, and mechanical resistance of bones of exposed animals.