How much is the safely tolerated value of fluoride (mg F/Kg)

Certainly lethal dose (CLD) - 32-64 mg F /Kg body weight Safely tolerated dose (STD) - 8-16 mg F / kg body weight (1/4th of CLD) Also note these two important values  Probable toxic dose (PTD)- 2mg F/ Kg body weight Minimum toxic dose (MTD)- 5-6 mg F/ Kg body weight.