Science Says What? is a monthly column written by Great Lakes now contributor Sharon Oosthoek exploring what science can tell us about what’s happening beneath and above the waves of our beloved Great Lakes and their watershed.
Microplastic pollution has been building up in the Great Lakes since at least the 1970s. In fact, according to research led by Western University in London, Ontario, there are now enough microplastic particles at the bottom of the lakes that they are becoming a permanent part of the sedimentary layer.
Sedimentary petrologist Patricia Corcoran predicts that centuries from now geologists will find them in rocks formed from successive layers of plastic-laced sediment.
“They’ll be a marker on the sedimentary horizon,” she told Great Lakes Now. “We’ll be known as that horrible group of humans who did this.”
Microplastics are the result of the breakdown of water bottles, plastic bags or other things that started out larger. Clothing made of fleece or nylon can also shed microplastic fibers when washed, and those go down the drain and into the environment. Some companies add tiny plastic beads to toothpastes and skin-care products to help scrub away tooth plaque and dead skin cells. Then they, too, wash down the drain.
According to the United States Geological Survey, there are 112,000 particles of microplastics per square mile of Great Lakes water. Scientists have found these tiny bits of plastic all over the world — even in mosquitoes’ bellies. Much of the contamination can be chalked up to the fact that we recycle only 9 percent of plastic waste. Of the remainder, about 12 percent is incinerated and 79 percent accumulates in landfills or the natural environment, including our lakes.
What is so bad about microplastics?
Plastic is a petroleum-based product made from many different chemical ingredients and scientists don’t yet know how all of these ingredients might affect human health or the environment. Still, they do know that some ingredients such as polyvinyl chloride cause cancer, while phthalates are endocrine disruptors. Endocrine disruptors are chemicals that mimic hormones, triggering unexpected changes in our cells’ growth and development. These chemicals can fake out our bodies’ normal signals and lead to disease.
Part of the problem is that microplastics are so tiny that they can get into our cells. British scientists recently showed damage to human cells in the laboratory at levels that we know we ingest with our food. The damage includes allergic reactions and cell death.
While that sounds scary, no one knows how long microplastics linger in our bodies before being excreted. Whether they hang around long enough to do damage is still a mystery.
The sponge factor
Research shows plastic acts like a chemical sponge, soaking up other pollutants from the water around it. For example, pesticides and other toxic compounds have been found in plastics floating in water and these plastics have turned up in the bellies of Great Lakes fish.
When University of Toronto researchers exposed larval fathead minnows to microplastics collected from Lake Ontario, the baby fish developed almost six times more deformities compared to when they were exposed “pristine” pre-consumer microplastics. This suggests microplastics in the lake soak up contaminants in the water and that it is these chemicals that are causing deformities.
The University of Toronto researchers are part of a group of scientists that is coming to understand that the particles’ damage is the result of a wide range of factors not generally considered in toxicology testing – the plastic’s size, shape and chemical makeup.
For example, the more jagged the shape of a microplastic, the more damage it does to the digestive tract of fish and other creatures. The same goes for size – the smaller the particle, the better able it’s able to slip out of the digestive tract and into the body, where it can irritate internal organs and cause harmful inflammation.
So what can we do?
The very nature of microplastics makes cleanup impossible. They are so tiny and so widespread that there is no way to remove them from the lakes. However, we can cut down the number of larger bits of plastic that find their way into the lakes. There’s a new fleet of remote-controlled robots coming to Great Lakes shorelines in spring of 2023 that will do just that.
The bots will collect plastic pollution from both the shoreline and the water as part of a larger binational effort called the Great Lakes Plastic Cleanup initiative. The effort includes installing in marinas something called Seabins – devices that look like trash cans in the water but behave like vacuum cleaners that can suck pieces of plastic out of the water. We can also take our cue from Great Lakes residents who have installed special filters on their washing machines to remove plastic microfibers from the machines’ waste water.
“Although washing our clothes in washing machines is just one source of microfibers to the environment, we know that it’s a significant source,” Chelsea Rochman, a microplastics researcher at the University of Toronto, told Great Lakes Now. “In the city of Toronto, we estimate as many as 23 to 36 trillion microfibers may be emitted to Lake Ontario watersheds each year.”
We can also support efforts to ban single use plastics and reduce our use of plastic by finding alternatives such as glass or paper. Some companies are starting to replace single-use plastic items with biodegradable alternatives made from a range of materials – trees, sugar cane and shrimp shells to name a few.
But the problem with such materials is that they decay only at very high temperatures — typically 50º Celsius (122º Fahrenheit). Plus, those high temperatures must be maintained for several weeks for microbes to do their job.
Some cities have industrial compost systems that meet those conditions. But many do not. Instead, biodegradable plastic items often end up in a cold lake where they can take decades or even centuries to break down, depending on the type of plastic.
Obviously microplastic pollution is a complicated problem that will take great effort to solve. But if we want to mitigate our reputation with future generations, we must find a way to avoid being “that horrible group of humans.”
Catch more news at Great Lakes Now:
Featured image: Plastics and microplastics on a beach (Great Lakes Now Episode 1004)