Formaldehyde

An aldehyde occurring as a colourless gas with a sharp smell. It dissolves in water and alcohol, and serves as a disinfectant and germicide; in solution it preserves biological specimens and acts as embalming fluid. It is sold as formalin, a 37–50% aqueous solution. Also known as methanal. It is not permitted as a food additive. Classified as carcinogenic to humans, it is strictly controlled as an industrial chemical; its notorious misuse as an illegal preservative in milk and fish in some regions prompts targeted surveillance with rapid test kits. Endogenous formaldehyde occurs naturally at low levels in foods such as fruits, but deliberate addition is prohibited worldwide.