Not even the very deepest, darkest depths of Earth’s oceans can escape mankind’s legacy of toxic pollution.

In a shocking discovery highlighting the interconnectedness of our planet, scientists have detected “extremely high levels” of organic chemicals in the fatty tissue of amphipods, a type of crustacean, living in Mariana trench ― the deepest part of the world’s oceans.

“We still think of the deep ocean as being this remote and pristine realm, safe from human impact, but our research shows that, sadly, this could not be further from the truth,” study author Alan Jamieson, a marine ecologist at Newcastle University in Britain, said in a statement.

The study, published Monday in the journal Nature Ecology and Evolution, reportedly provides the first evidence that man-made pollutants have reached the planet’s most far-off areas, according to those behind the research.

Alan Jamieson/Newcastle University Hirondellea gigas are voracious scavengers that consume anything that comes down from the surface.

Along with the nearly 7-mile deep Mariana trench in the North Pacific, Jamieson’s team deployed landers to Kermadec, a slightly shallower trench in the South Pacific. Amphipods collected from both of these remote locations were found to contain “extraordinary levels of persistent organic pollutants.”

The contaminants, including industrial polychlorinated biphenyls, or PCBs, and polybrominated diphenyl ethers, or PBDEs, were found “in all samples across all species at all depths in both trenches,” at levels “considerable higher than documented for nearby regions of heavy industrialization,” according to the findings.

Disturbingly, the highest levels of PCBs ― compounds widely used in electrical equipment until they were banned in the 1970s ― were detected in Mariana trench at concentrations 50 times that of crabs from China’s heavily polluted Liaohe River.

The researchers say the most logical explanation for the accumulation of these toxic compounds in such isolated areas is that plastic marine debris and dead animals contaminated at the surface sank through the water column. Once at the bottom, they were consumed by deep-sea species.

Jamieson stressed that the legacy we humans are leaving behind is not a good one and that the findings “really bring home the long term, devastating impact that mankind is having on the planet.”

“We’re very good at taking an ‘out of sight, out of mind’ approach when it comes to the deep ocean but we can’t afford to be complacent,” he said in a statement.