There are no natural sources of polychlorinated biphenyls only natural sinks, such as Killer Whales and other predators. As such, PCBs are part of the pattern of whorls and loops that make up the human fingerprints we’re learning to understand as the Anthropocene: spooky fingerprints that circulate around us within other living beings.
Unlike many other toxins, greenhouse gases and agrichemicals we still churn out in record-breaking amounts, PCBs are “a ghost from the past. These chemicals were produced in immense quantities from the 1930s onwards and were broadly phased out in the 1970s/1980s as environmental concerns grew.”
Soluble in fat, once ingested, PCBs accumulate in fish, mammals and birds, so their haunting persists in the world’s food chains. And this “legacy of PCBs will continue … for some while to come. Scientists estimate that the final resting place or ‘sink’ for PCBs is likely to be organic-rich soils across the Northern Hemisphere or even ocean sediments.” PCB body levels will likely reduce, but the kick in the cocktail is climate change, which can alter the abundance of different PCB-laden prey, and trigger “bioamplification, meaning an increased concentration of pollutants in the bodies of marine animals when they lose weight.”