Persistent pollutants, persistent threats

Persistent organic pollutants (POPs) are chemical substances that persist in the environment, accumulate in the food web, and pose a risk of adverse effects in humans and wildlife ( 1 ). Rachel Carson first identified the potentially devastating effect of POPs on wildlife in the early 1960s ( 2 ). In the late 1960s, polychlorinated biphenyls (PCBs) were detected in high concentrations in wildlife in Sweden ( 3 ). After PCB use and manufacture were banned in 1979 (US), 1981 (UK), and 1987 (EU), levels started to decline slowly in all biota around the world ( 4 – 6 ). In 2004, the Stockholm Convention committed more than 90 signatory countries to phasing out or eliminating large stocks or other sources of POPs, including PCBs ( 1 ). Yet, PCBs continue to threaten the survival of marine predators. Concerted efforts are thus still needed to mitigate PCB pollution.