Sources and prevalence of pentachlorobenzene in the environment

There are no longer any large scale uses of pentachlorobenzene (PeCB). Current emissions of PeCB to the environment are estimated to be about 121 000 kg y−1, based on published information. The largest sources appear to be combustion of solid wastes, 32 000 kg y−1, biomass burning, 45 000 kg y−1 with degradation of an agricultural fungicide, quintozene, contributing 26 000 kg y−1 and industrial releases less important. PeCB has been measured in many environmental media over the past 35 years. Low but detectable concentrations of PeCB have been reported in the atmosphere, sediments and biota in remote areas of the world. Calculations using a global distribution model are consistent with the estimate of approximately 100 000 kg y−1 global PeCB emissions. Concentrations of PeCB in the environment have declined with a 90% decrease of PeCB concentrations in herring gull eggs from Lake Superior, Canada since 1979.