|MadSci Network: Zoology|
PCBs (polychlorinated biphenyls are chlorinated aromatic hydrocarbon chemicals that have been in commercial use for over 50 years. They are resistant to degradation and persist for long periods of time in the environment. In 1979, EPA prohibited the manufacture of PCBs in the U.S. and provided for severe restrictions and an orderly phaseout of all uses during a 5 year period. There is a wealth of data in the scientific literature on its toxic effects, and they are such a low order of acute toxicity to be labeled as legally nontoxic. From animal studies, PCBs are also described as a relatively low order of toxicity chronically. In rodents PCBs, similar to all chlorinated hydrocarbon compounds, produced liver tumors and cancer. They have not been shown to cause liver cancer in other species, including humans. There have been no studies on the toxicity of PCBs in orca whales. It is not logical to think that Puget Sound will be highly polluted by PCBs in the future. That is not to say that other commercial products may enhance pollution within these waters.
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