Fluoride Action Network


Rats were given Na18F as a radiotracer for F- at varying chemical dose rates by continuous i.v. infusion for 3 h. Blood fluoride was assessed 6-7 times over the infusion period, at the end of which the animals were sacrificed for determination of tissue fluoride distribution. At sublethal dosages, the rate of blood fluoride concentration approaches a steady state proportional to the rate of fluoride infusion. Blood, kidney and lung contained the highest fluoride concentration at doses up to 3.6 mg of F/kg per h, but at 6 mg/kg per h the fluoride of liver, spleen and hollow organs increased sharply indicating this dose exceeded the amount readily processed by the fluoride excretory mechanisms of the body. Another group of animals was infused for 3 h with 6 mg of F/kg per h, a dose which approaches the acute LD50. Tissue fluoride distribution was determined at various intervals during both fluoride accumulation and depletion phases. During infusion the fluoride concentration of blood and other tissues was high, with highest accumulation in bone. Of soft tissues, lung contained the greatest amount of fluoride, and brain, testes and fat pads the least. During the depletion phase, tissue fluoride concentrations decreased sharply, while bone fluoride remained constant and substantial amounts remained in lung. (Fluoride toxicity is considered.)