Sodium diacetate (SDA) is a molecular complex of sodium acetate and acetic acid. In Japan, it is also called monosodium diacetate or solid acetic acid. It is a white crystalline powder, hygroscopic in nature, with a faint acetic acid smell and flammable. It is easily soluble in water and ethanol and has extremely low toxicity. The oral LD₅₀ is 3.31 g/kg for mice and 4.96 g/kg for rats, with an acceptable daily intake (ADI) of 0–15 mg/kg. It is completely metabolized into water and carbon dioxide in organisms, leaving no residue and posing no hazards to humans, animals or the ecological environment. Classified as a Group O safe substance by the World Health Organization, it is non-toxic, non-carcinogenic and non-teratogenic. Endorsed by FAO and WHO, it is widely applied as a mildew inhibitor, preservative and fresh-keeping agent in food, grain and feed industries.