Known and potential sources of hexachlorobenzene.

Five active pesticide ingredients and five industrial organic chemicals are known sources of hexachlorobenzene (HCB). However, identification of the reactions and the chemical intermediates that lead to HCB formation, combined with computerized substructure searching of the scientific literature, indicate an additional 135 active pesticide ingredients and 21 industrial chemicals and classes that are suspected of potential for HCB formation. The production of these and many other chlorinated chemicals, together with special chlorination processes such as municipal incineration, wood-pulping and water chlorination, may explain the ubiquitous nature of HCB in the environment.