Soil To estimate the PCB burden in British soils, we have used the data of Alcock et al. (1993) from a survey of 39 rural and urban soils from northwest England. The data we have used are based upon a sampling depth of 5 cm. Therefore, if the surface area of the UK not under freshwater is taken to be 2.475 × 101 m² (Geo-data, 1983) and average soil bulk density as 1000 kg m 3, the top 5 cm of UK topsoil will weigh 1.24 × 10¹³ kg. As a cautionary note, in view of the fact that PCBs are to be found, albeit at lower concen- trations, at depths below 5 cm, the actual quantity of PCBs associated with British soils is likely to exceed the burdens listed below, perhaps by a factor of two or more. It is also possible that we have selected data that are unrepresentative of typical UK levels. Specifically, the levels quoted here are higher than those previously reported for rural UK soils by Creaser et al., (1989). Although we feel that any such error is unlikely to be major, the effect on the overall soil burden of either decreasing or increasing the assumed typical PCB level in UK soils is obvious. Despite such reservations as to the precise loading, it is clear that soils represent a major sink for PCBs in the UK. Both the concentra- tions used and the calculated soil burdens are included