Estimation of hexachlorobenzene pathways from the technosphere into the environment.

Since there are many different pathways from the technosphere to the environment, hexachlorobenzene (HCB) is widely distributed, supported by high mobility and high persistence. Several different assumptions were made about HCB inputs to air or water and, by simple calculations, potential HCB concentrations in water, air, sewage sludge and sediment were estimated. By comparing the results with measured environmental concentrations, maximum amounts of HCB released into the environment were estimated, and the relative importance of the water and air pathways appraised. Results showed that of the total HCB produced, the fraction that is released into the environment is substantially smaller than has been estimated. Despite the estimates of world-wide annual input of 10-100 t, it is well known that HCB is detected in relatively large amounts in most living tissues. This emphasizes the importance of the persistence of HCB, and of other environmental chemicals.