In an earlier issue of this journal attention was drawn to the possibility of disposing of persistent aromatic pollutants, including polychlorodibenzo-p -dioxins (PCDDs), by an oxidation process which utilised catalytic quantities of ruthenium tetroxide (1).

Since that time there has been a growing awareness of the potential danger to human health posed by polychlorinated biphenyls (PCBs), compounds with similar structures to the PCDDs. PCBs were widely used in the past as insulators in electrical transformers and capacitors. They are very stable, and therefore difficult to get rid of when they are no longer required. Burial in a landfill site cannot be regarded as a permanent solution as leaching into the drainge system may occur. Incineration, the usual alternative method of disposal, requires temperatures of around 1200°C and risks the possibility that even more toxic polychlorinated dibenzofurans could be formed if the process conditions are not controlled satisfactorily. Although various chemical methods of detoxification have been reported the unreactivity of PCBs generally necessitates the use of extreme conditions. However, a simple, efficient method for the oxidative destruction of PCBs has now been reported by investigators at the University of East Anglia and at Queen Mary College, London (2).

Their procedure makes use of ruthenium tetroxide as an oxidising agent, and complete destruction can be achieved. The rate of destruction of individual polychlorinated biphenyl isomers varies, resistance to degradation depending on the degree of chlorination of the biphenyl. The method is said to be suitable for the detoxification of laboratory equipment, and to have possible application for the large scale treatment of commercial waste fluids.