Dietary uptake and elimination of selected polychlorinated biphenyl congeners and hexachlorobenzene in earthworms.

Earthworms (Eisenia foetida) were given food contaminated with hexachlorobenzene (HxCBz) and 20 tetra- to heptachlorinated biphenyls (PCBs). The PCBs were selected to cover a wide range of physicochemical properties. The uptake efficiencies, uptake rate constants, and elimination rate constants in worms varied between the 20 PCBs. The uptake efficiencies were between 10 and 68%. The PCBs that were eliminated fastest contained few chlorine atoms, had more polar characteristics, and were sterically hindered. Slowest was the elimination for less polar PCBs with six or seven chlorine atoms such as the non-ortho-substituted PCB 169. Elimination half-lives varied between 6 and 25 d. The biomagnification factors (BMFs) for the PCBs and HxCBz averaged 0.1 based on lipids and 0.04 based on wet (worms) and dry (food) weight. Worm cocoons were analyzed for PCBs for the first time. The PCB pattern in the cocoons differed from the adult worms by the comparatively higher load of non-ortho PCBs. By studying congeners covering a large range of PCB physicochemical characteristics, their fate within the environmental and the factors influencing biological responses can be better understood.