The industry itself has devised further control methods. The remainder of this paper consists of a discussion of the chemistry and toxicity of sodium nitrite, an explanation of how it is handled and controlled and an analysis of the chemical hazard it presents in meat curing. Nitrite acts as an oxidizing agent, and in the mildly acidic conditions of meat a small quantity of nitrous acid is formed. One of the reactive species formed subsequently is nitric oxide, and it is the active nitrosating agent. The level of nitrite analytically detectable in cured meat is greatly reduced from the amount added because the nitrite reacts with components of the meat during processing and storage.
Sodium nitrite is a toxic substance, and at sufficient dose levels, is toxic in humans.
The 1963 text by Gleason et al gives sodium nitrite a toxicity rating of 4 . Sodium nitrite must be swallowed or injected to produce poisoning and has two basic modes of action. Methemoglobinemia renders the hemoglobin incapable of carrying oxygen. Very young children, because of the presence of the fetal form of hemoglobin, which is more sensitive to oxidation, are more susceptible than adults. Of interest is the fact that low doses are used therapeutically.