A study undertaken by an international research team has found that almost half of the world’s killer whales are under threat of extinction due to high levels of toxic pollutants in the oceans, especially poisonous chemicals like PCBs.
Although PCBs have been banned around the world for decades, they are still leaking into the seas. They become concentrated up the food chain; as a result, killer whales, the top predators, are the most contaminated animals on the planet. Worse, their fat-rich milk passes on very high doses to their newborn calves.
PCB concentrations found in killer whales can be 100 times safe levels and severely damage reproductive organs, cause cancer and damage the immune system. The new research analysed the prospects for killer whale populations over the next century and found those offshore from industrialised nations could vanish as soon as 30-50 years.