Sodium fluoride, NaF, is a binary salt that is a clear, lustrous crystal or white powder. The insecticide grade is frequently dyed blue. It is soluble in water and has a specific gravity of 2.558, which is heavier than water. Sodium fluoride is highly toxic by ingestion and inhalation, and is also strongly irritating to tissue. The TLV is 2.5 mg/m^3 of air. THE four-digit UN identification number is 1690. The primary uses are fluoridation of municipal water at 1 ppm, as an insecticide, rodenticide , and fungicide, and fungicide, and in toothpastes and disinfectants.