Differential retention of PCB congeners in cockroaches Blattella germanica.

Organisms differ widely in their ability to metabolize and eliminate polychlorinated biphenyls (PCBs). We evaluated the retention of PCB congeners, reference standard mixture, experimentally injected into cockroach Blattella germanica, in relation to sex and time, and its elimination through the feces, exuviae and oothecae. The nymphs that died prematurely had a higher average PCB retention than those with a longer lifetime, 88% of the injected dose for those that died within 1 to 10 days, and 76% for those within 11-20 days. Diverse PCB congeners showed differential retention, and particularly the more volatile, low weight congeners were recovered in lower concentrations, the medium-weight ones were intermediate, while the high-weight congeners attained the highest concentration. PCBs were also detected in the excrements and in exuviae, which may therefore act as detoxification paths, and in the oothecae, thus showing that PCBs can be transferred from mother to progeny.