An Erred Chemical Past Returns to Roost - PCBs Threaten to Doom some Orcas

A chemical - polychlorinated biphenyl, or PCB - once heavily and widely used in industry in the manufacture of plastics, sealants, paints and coolants, but banned largely in the 1980s because of its toxic property, has returned to wreak havoc upon the ecology of the seas. And according to a new study, the difficult to destroy chemical now threatens into extinction as much as 50% of the world's killer whale population.

Citing a study published in Science Magazine, the BBC-News reported that killer whales, orcas, are in dire trouble because of persistent chemical pollution in the environment. The study said long-term viability of more than half of the different orca groups around the world is now in question, the BBC-News added.

That orcas are top predators in the seas put their viability in danger because they absorb all the PCB pollution taken in by different prey in their food chain from fish, right up to seals and sharks, the BBC-News explained from the study. PCBs toxify the reproductive success and survivability  of the orcas. Thus, in polluted waters like the west coast of Scotland, the killer whale population is now down to just eight individuals who have not produced a calf in more than 20-years. One scientist believes this group will disappear in his lifetime.

However, the outlook appears brighter for orcas living in cleaner waters at the Arctic and Antarctic, where numbers are expected to increase.

Yet, for the mammals living in the most polluted water, the BBC-News reported that the next 30-50 years will be grim for them.

Therefore, in order to save the orcas and other sea life, a better disposal method of PCBs becomes urgent. "Improper disposal of PCB-containing equipment in landfills may lead to leakage and leaching of PCBs into nearby streams, rivers, estuaries, and oceans", the lead author of the study, Jean-Pierre Desforges, of Denmark, is quoted as warning.