Scientists have discovered chemical pollutants nearly 33,000 feet below the ocean's surface in the Mariana Trench, the BBC reports.
Chemicals banned in the 1970s by the EPA – PCBs and PBDEs – were found in the deep sea by researchers from the University of Aberdeen. Their findings were presented Monday in the journal Nature Ecology and Evolution.
PCBs, or polychlorinated biphenyls, were manufactured and processed primarily for use as insulating fluids and coolants in electrical equipment and machinery. PBDEs are classed of brominated hydrocarbons and were formerly used as additive flame retardants in synthetic fibers and molded plastics.
Researchers checked for the presence of PCBs and PCDEs in the Mariana Trench in the Western Pacific and the Kermadec trench north of New Zealand. They caught tiny shrimp-like crustaceans called amphipods and tested them for the chemicals and found that PCBs and PCDEs were present in all species of amphipods in both trenches, at all depths.
"Contaminant levels were considerably higher than documented for nearby regions of heavy industrialization, indicating bioaccumulation of anthropogenic contamination and inferring that these pollutants are pervasive across the world's oceans and to full ocean depth," reads the report.
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