A manmade chemical that was banned in the 1970s has, along with other human-produced toxins, made its way to the bottom of the ocean.

A manmade chemical that was banned in the 1970s has, along with other human-produced toxins, made its way to the bottom of the ocean. 
Researchers led by Dr. Alan Jamieson of Newcastle University in the U.K. have confirmed that evidence of dangerous pollutants, including the PCBs, was found in both the Mariana and Kermadec trenches, which are nestled deep in the Pacific Ocean. 
Traces of the contaminants were present in amphipods that occupy the two regions. 
A press release about the study notes, "From the 1930s to when PCBs were banned in the 1970s, the total global production of these chemicals was in the region of 1.3million tonnes.  Released into the environment through industrial accidents and discharges and leakage from landfills, these pollutants are invulnerable to natural degradation and so persist in the environment for decades."
The team believes the substances made it to the far reaches of the waters through sinking debris and contaminated, deceased animals.
Dr. Jamieson commented, “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. In fact, the amphipods we sampled contained levels of contamination similar to that found in Suruga Bay, one of the most polluted industrial zones of the northwest Pacific.” 
He also noted, “The fact that we found such extraordinary levels of these pollutants in one of the most remote and inaccessible habitats on earth really brings home the long term, devastating impact that mankind is having on the planet. It’s not a great legacy that we’re leaving behind.”