The alarming conclusion could have widespread consequences for humans and wildlife that ingest those tiny particles, a pair of academic articles says. What those consequences are remains to be seen, and without a coordinated strategy between the two countries that share the Great Lakes, scientists say we'll struggle to understand the scope of the problem.
Without a better plan, researchers in the U.S. and Canada are "flying blindly" as they work to prevent more plastics from seeping into the environment, one scientist said.
"You're just crossing fingers, hoping that what you do is making a difference," said Dr. Chelsea Rochman, an eco-toxicologist at the University of Toronto.
"The data shows the Great Lakes are widely polluted with microplastics," said Eden Hataley, a PhD student who works in Rochman's lab and co-authored the research.
Chemicals of Mutual Concern
There are challenges to ramping up a bi-national monitoring program like what Hataley and Rochman are pitching.
One way to make it easier would be to classify microplastics on the list of Chemicals of Mutual Concern. The first list came out in 2016, which came with commitments from both neighboring countries to identify, target, and reduce their presence.
While all forms of plastic pollute the world, tracking the sources of the big stuff - packaging materials and food waste containers - isn't that difficult. But the fibers that wash off clothes and particles that can't be seen without a magnifying glass are harder to monitor.
That includes plastics in several fish that grow in the Great Lakes, prompting advisories about how much one can safely consume.
Lacking a plan creates another issue Hataley says - the scientists gathering data aren't talking to one another or policymakers.
"It came from different research groups and nonprofits, who were all collected in silos of one another," she said. "So you have different people doing different work."
The past 10 years of research have helped show just how pervasive microplastics are in the environment, as well as the sources that most commonly produce them. And while it's unclear what that means for humans, Rochman is confident in at least two ways that microplastics effect animals.
Eating more plastic means there's less room in a fish's stomach, which can reduce growth, harm reproduction, and be less likely to survive. Small particles are also found in the organs of animals, which can cause stress and inflammation, leading to tumors.
"When we see exposure to a tumor in fish, we do see microplastic," Rochman said.
There's also been less reported effects like a disruption of hormones and a softening of shells similar to what was observed in the eggs of Eagles when DDT was used.
Ramping up a Strategy
The term microplastics was first coined in 2004 by Dr. Richard Thompson from the United Kingdom. However, they didn't reach mainstream concern until 2015 when a study showed the single application of a tool like facial scrubs released nearly 100,000 microbeads into the environment.
It eventually led to the ban of rinse-off cosmetics in the U.K. Further industry regulations have since followed in other countries.
In pitching a strategy between the U.S. and Canada, Hataley and Rochman hope to see similar progress turn into policy.
Monitoring would not just narrow in on the hot spots of the environment or when they're most actively polluting, but serve as the first stage in making sure those contaminants are either caught before spreading further - or being kept out of the environment entirely.
Some of the highest concentrations of microplastics have been reported in urban rivers - like the Rouge River and Huron River in Southeast Michigan due to runoff. Wastewater treatment plants are also considered big sources of microplastics since it collects the same water used to wash clothes.
Both will play a major role in monitoring and removal, Hataley says, because they serve as choke points for microplastics.
"Cleanup is good, but it should not trump prevention," she said.
Monitoring would also help coordinate clean-up efforts between governments, as well as isolate which materials shed plastic the most.
It would also help answer some more unusual questions that have appeared, like why a vast majority of samples in water detected microplastics, but not in the sediment sitting beneath the water.
Rochman says she could see a coordinated monitoring strategy in place in five years.
"There's a lot of talk from the U.S. and Canada," she said. "We're trying to bring in people on different continents, but both governments are listening. It's an optimistic answer, but it is realistic."