Related Content Your Garbage Is Polluting Even The Deep, Remote Reaches of the Ocean

The Great Lakes represent one-fifth of the entire world’s fresh surface water. Thirty percent of the Canadian population lives in the Great Lakes basin, as do 10 percent of Americans. And yet, for whatever reason, no one wondered how the Great Lakes were doing when it comes to plastic contamination. As it turns out, they’re not doing so great.

For the past decade or so, the public imagination has been swept up by the tale of the Great Pacific Garbage Patch, a sprawling region in the central North Pacific ocean littered with plastic debris—mostly small pellets of highly eroded material that became trapped in a vast rotating ocean circulation known as the North Pacific Gyre.

An as-of-yet unpublished study by researchers from the State University of New York – Fredonia, led by chemist Sherri Mason, found that three of the five Great Lakes—Erie, Huron and Superior—had plastic contamination that, in the worst cases, outpaces those of the Great Pacific Garbage Patch. The Toronto Star:

Two of the 21 samples they collected contained 600,000 plastic pieces per square kilometre — nearly twice as much as the highest plastic count ever recorded in the infamous Great Pacific Garbage Patch. “Those are very high counts,” Mason said. The team’s least-polluted sample contained 600 pieces per square kilometre.

The plastic particles were typically smaller than those found in the Pacific, being less than 5 millimeters wide in general. This means that, though there may be more plastic pieces in some cases, the total mass of plastic is smaller. But still, that may not be a good thing. The Windsor Star:

Small plastic particles are particularly problematic because small animals and fish can eat them, potentially affecting the entire food chain as bigger animals eat those animals.

EcoWatch.org:

“You don’t find microplastic in the ocean like we did in the lakes,” Mason said. “Somewhere in between there it disappears, and we want to know where it’s going.” Mason and her colleagues think that the microplastics could be washing up on beaches, or that it may be entering the food chain if consumed by microorganisms or fish. “There’s this uncertainty right now, so one of the next things we have to do is get out on a boat and look at the food chain to see if the plastic shows up,” Mason said.

Since the study has not yet been published, the specific details of the findings aren’t locked in yet. And follow-up research certainly needs to be done to figure out where the plastic came from and what effect, if any, it is having on the Great Lakes ecosystem. But the main result, that there are huge concentrations of teeny plastic pellets floating in the Great lakes, probably isn’t going anywhere. Neither, for that matter, are the plastic pellets.

More from Smithsonian.com:

High Levels of Plastic and Debris Found in Waters off of Antarctica

Synthetic Bacteria Could Turn Ocean Garbage into One Big Island

Face to Face With a Garbage Patch at Sea