Plastic pollution – most of it from our clothing and fabrics, surprisingly, and some of it decades old – is piling up in biodiversity hotspots in the ocean, new research shows. Once microplastics fall to the ocean floor, small marine animals living in sediment layers can ingest it, establishing one route by which plastics enter the human food chain.

“The real problem is plastics (sitting) in the environment (that) can accumulate various pollutants and toxins on their surfaces,” said researcher Ian Kane, PhD, of the University of Manchester. “There’s evidence that some of these toxins may be released when in the guts of organisms, and then you have the effect of the food chain, whereby small creatures are eaten by bigger creatures, and eventually you get to our fish stocks and you’re eating a nice piece of tunas containing decades-old microplastics contaminated with all sorts of nastiness.” Dr. Kane was lead author of the recent study.

It turns out that ocean currents and deep-sea water circulation act as “conveyor belts,” he explained in a recent Guardian article reporting the new study. They deposit microplastics in concentrated amounts, similar to the concentration we see in the “garbage patches” of plastic debris visible on the surface of the Pacific.

While it has been widely assumed that microplastic pollution starts with the breakdown of larger pieces of plastic, this study found most it came from textiles and clothing. It’s another reason to champion the circular economy for clothing and move away from petroleum-based materials. At the same time, Kane said, the waste and water treatment industries have key roles to play by using filters to block the transport of microplastics into the ocean.

Biodiversity hotspots are important breeding grounds for marine life. They shouldn’t also be breeding grounds for food contamination with plastics.