Fluoride ion is poisonous in relatively low amounts: 0.2 g of f- per 70 kg of body weight can cause death. nevertheless, in order to prevent tooth decay, f- ions are added to drinking water at a concentration of 1 mg of f- ion per l of water. how many liters of fluoridated drinking water would a 70-kg person have to consume in one day to reach this toxic level? how many kilograms of sodium fluoride would be needed to treat a 8.5 x107-gal reservoir?