At the deepest spot in the ocean, scientists have found beer cans, plastic bags, a tin of Spam, and now tiny crustaceans contaminated with toxic chemicals banned nearly 50 years ago. The "extraordinary levels" of pollution in the Mariana Trench in the western Pacific Ocean and the Kermadec Trench some 4,000 miles away, initially described last summer, are now laid out in a study published in Nature. Researchers say toxic industrial chemicals called persistent organic pollutants, or POPs, known to affect reproduction, were found "in all samples across all species at all depths in both trenches," they tell the Guardian. Adds lead researcher Alan Jamieson, "the surprise was just how high the levels were—the contamination in the animals was sky high."
POPs—including polychlorinated biphenyls, or PCBs, which were banned in the 1970s—have leaked into oceans and accumulated in animals, which sink to the deep ocean when they die. They're then eaten by scavenging amphipods like those in Mariana Trench, which are more contaminated with PCBs than crabs living in some of China's most polluted waters, USA Today reports. At the Conversation, Jamieson compares the use of plastic microbeads to that of POPs, noting "we have a shocking example of our own stupidity, as people gradually realize … that stuff that goes down the sink doesn't magically disappear into another dimension." He adds researchers are now surveying amphipods in the trenches for plastic pollution he is sure will be there. (Mariana Trench is home to a 3.5-second symphony.)