Sodium Meta Bi Sulphite is one of a group of preservatives known as bisulphite. It is a food preservative, cosmetic and industrial bleaching agent, and an ingredient in the developing solution for film and photography. Evidence exists that it is also an immune-system toxin. As part of the group of sulfites, sodium metabisulphite can provoke reactions in people, particularly asthmatics, ranging from gastrointestinal discomfort and hives to asthma attacks.