The chemical reactions and pathways involving hexachlorocyclohexane, a cyclohexane derivative with 6 chlorine atoms attached to the hexane ring. Hexachlorocyclohexane consists of a mixture of 8 different isomers and was used a commercial insecticide. It is persistent in the environment, causing serious soil pollution. [ http://eawag-bbd.ethz.ch/ghch/ghch_map.html http://eawag-bbd.ethz.ch/hch/hch_map.html ]