 They found that the average PCB concentrations in the blubber were approximately four times higher than the liver; however, this result is most likely age- and sex-dependent.As reproductively active females transferred PCBs and other poisonous substances to the fetus, the PCB concentrations in the blubber were significantly lower than males of the same body length (less than 13 meters).The toxicity of PCBs varies considerably among congeners.