Sodium nitrite is an inorganic compound with the chemical formula NaNO2. It is a white to slightly yellowish crystalline powder that is very soluble in water and is hygroscopic. From an industrial perspective, it is the most important nitrite salt. It is a precursor to a variety of organic compounds, such as pharmaceuticals, dyes, and pesticides, but it is probably best known as a food additive used in processed meats and (in some countries) in fish products.Sodium nitrite is toxic. The LD50 in rats is 180 mg/kg and in humans LDLo is 71 mg/kg. The mechanism by which sodium nitrite causes death is methemoglobinemia. The oftentimes severe methemoglobinemia found in sodium nitrite poisoning cases results in systemic hypoxia, metabolic acidosis, and cyanosis.