Substances which cleanse the skin surface. This means that, strictly speaking, any soap, or soap-like substance used in washing, is a detergent. However, the term is largely used for synthetic detergents prepared from high petroleum waxes and sulphuric acid. The commoner ones in commercial preparations are aryl alkyl sulphate or sulphonate and secondary alkyl sulphate.

Perhaps surprisingly, such detergents cause relatively little trouble with the skin, but problems have been reported with the so-called ‘biological’ detergents – so named because they contain an ENZYME which may cause DERMATITIS. In addition, they have been reported to cause ASTHMA in some who use them and in workers who manufacture them.