 Traces of PCBs were found in food (eggs, cow milk, walnuts) and Krupa is still the most PCB-polluted river in the world.Several cetacean species have very high mean blubber PCB concentrations likely to cause population declines and suppress population recovery.Striped dolphins, bottlenose dolphins and killer whales were found to have mean levels that markedly exceeded all known marine mammal PCB toxicity thresholds.