Benzene is the simplest aromatic compound, with a ring of six carbon atoms and six hydrogen atoms. It is a colourless liquid occurring naturally in fossil raw materials such as crude oil and coal, produced during processing of petroleum liquids and through chemical reactions.

It is one of the most important feedstocks for the chemical industry, used for the manufacture of a wide range of everyday items, and is not itself used directly by consumers.

The limit of benzene in petrol in Europe is 1,0 % v/v. Benzene may cause genetic defects and cancer, causes damage to organs through prolonged or repeated exposure, is a highly flammable liquid and vapour, and causes serious eye and skin irritation (source: ECHA).