SYSTEMIC FLUORIDE POISONING FOLLOWING DERMAL HYDROFLUORIC-ACID EXPOSURE - DEVELOPMENT OF AN INTRAVENOUS-SODIUM FLUORIDE INFUSION MODEL IN RATS

The effect of dermal exposure to concentrated (48% w/v) hydrofluoric a cid (HF) on survival and plasma fluoride concentration was investigate d in rats. Results of dermal exposure to abdominal and back skin were compared with intravenous administration of sodium fluoride. Dermal HF exposure on 6 cm(2) for 5 min resulted in toxic plasma fluoride conce ntrations. The location of application on the body influenced both the survival time of the rats and the kinetics of plasma fluoride concent rations. After abdominal application of 0.25 or 0.5 mi HF, a 50% morta lity rate within 300 min (time of death between 75 and 270 min) was ob served. After application of 0.25 mi HF on the back all rats survived the 315 min observational period while after application of 0.5 mi HF an LD(50) was reached (time of death between 280 and 314 min). Abdomin al exposure caused a gradually increasing plasma fluoride concentratio n while after exposure on the back a rapid increase of the plasma fluo ride concentration was observed, followed by a gradual decrease to a r elative constant level. It is concluded that, after the initial exposu re of the back, the back skin tissue layers act as a slow-release stor ehouse of fluoride. The course of plasma fluoride concentrations after skin exposure of the back to 0.5 mi HF could be simulated by a two-ph ase sodium fluoride infusion model. A loading dose of 1.2 mmol/kg/h du ring 30 min is followed by a maintenance dose of 0.3 mmol/kg/h.