How do microplastics enter our water? And what effect does that have on the environment?
Plastic can take anywhere from 20 to 500 years to decompose, depending on the material's structure and environmental factors such as sunlight exposure. Even then, it doesn't fully decompose — it just continues breaking down into smaller and smaller pieces, known as microplastics. These tiny bits of plastic are ubiquitous in the world’s waterways, including our oceans, rivers, and creeks. Microplastics have been linked to adverse health effects for humans and animals.
How plastic end up in our local streams
Wednesday morning, I met with Emily Fritz, a volunteer coordinator for Sound Rivers, as she and her team cleaned out a trash trap in a New Bern creek. We put on our waders and plucked trash out of waist-deep water.
“The trap is a good visual reminder for folks to see where plastic and trash end up if it's not disposed of properly,” Fritz said.
The trap is in a residential area near J.T. Barber elementary school. Fritz and her team picked up bottles, plastic bags, lots of tiny pieces of Styrofoam, and a toy dinosaur.
"We always have the weird stuff we find in the mix," she said. "It keeps it interesting."
A month ago, they collected more than 80 pounds from the same trap. On Wednesday, they pulled out 27 pounds.
A lot of the trash ends up in the creek from stormwater runoff and litter. Rain, wind and litter are the primary ways large plastic end up in waterways, says Ted Wilgis, director of the North Carolina Coastal Federation’s Marine Debris Program.
“A lot of people just don't realize how much material there is out there," Wilgis said. "Ranging from very large pieces of lumber to tiny microplastics, it's sometimes very hard to see and understand.”
Over time, plastic waste, like wrappers, packaging and straws, break down into smaller and smaller pieces – never quite going away completely. Microplastics are those tiny pieces – often less than 5 millimeters long.
“Anything on the road, anything on the land once it rains, it has the opportunity to flow into our local creeks," Wilgis said.
The Coastal Federation focuses a lot of large debris. Since Hurricane Florence in 2019, they’ve removed 2 million pounds of large debris — mostly lumber and abandoned boats. Microplastics, however, are harder to clean up.
“It's very cost prohibitive, I believe, to filter out some of the micro plastics micro-contaminants that end up in the wastewater stream," he said. "Once it's in the environment, it's very hard to remove it, so that's why we're trying to do the prevention aspect of things.”
One major contributor is Styrofoam, or polystyrene. Last year, the Coastal Federation sampled North Carolina beaches, from Sunset Isle up to Sneads Ferry. They found foam was by far the most common. Wilgis says his team has spent hours cleaning up foam from an unsuspecting source.
“So some piers and floating docks are built with large sheets or blocks of polystyrene, and if you don't cover that with some kind of hard material, it breaks down," Wilgis said. "Our crews have found areas of the marsh where it looks like it's snowed. It's just little bits of polystyrene that have broken off afloat because animals actually eat it.”
Working with coastal businesses to replace plastic and polystyrene packaging with biodegradable alternatives is one solution. Another is banning unprotected polystyrene floating docks. But trash is not the only way plastics enter our waterways.
“The other way is through our house, through our wastewater," Wilgis said. "So, as we wash our clothes as we take showers, all those things generate small particles and you know they can get washed into our wastewater treatment system.”
That polyester sweater. the plastic water bottle or cutting board in your dishwasher, even your nail polish, shed tiny flakes of plastics that go uncaught in wastewater treatment systems. More than a million tons of plastic are released into wastewater every year in the U.S., according to the Earth Day Network. Once that wastewater is treated, it’s released into our waterways, meaning that microplastics are ubiquitous.
Microplastics found in the tissue of marine animals
Greg Merrill is a researcher at the Duke Marine Lab in Beaufort. He pulled a plastic bag from the freezer. In it, a sample from a dolphin he used in a study that will soon be published in the October 15th edition of Environmental Pollution, a scientific journal.
“We wanted to know whether or not microplastics that whales and seals are ingesting. Just didn't just move through the body and out through defecation, or if any parts, any portion of those plastics end up in the body elsewhere. So, we looked at. I was thinking about blood or tissue specifically because it's really. Microplastics have this quality called their lipophilic, which means they are fat loving. They're chemically attracted to to fat, so I hypothesize that that might be a location that they'd end up.”
His study took samples from 32 whales, dolphins and seals, and found that two-thirds of them had microplastics in their blubber or lung tissues. His findings show these microscopic plastic particles can travel out of the digestive tract and become a part of the body.
“For me, one of the biggest things is the fact one sample was from 2001 and there was another 2005. It just underscores that this been happening for quite a while," Merrill said. "It's wild to me that some proportion of their body weight is made of plastic."
These tiny fragments are probably not from a whale eating a plastic bag, but rather microplastics working their way up through the food chain.
“Probably the the most significant route is through this process. Called trophic transfer, which means the food they're eating has already eaten plastic themselves. So small little animals are ingesting the microplastics, and then the whales are eating things like krill and fish. And so it gets it ends up in them, ultimately.”
Merrill said it's not known yet whether the presence of microplastics in these tissues can be benign or harmful. From looking at other studies, Merrill anticipates these microplastics will likely cause harm.
“We do know that they act that way as endocrine disruptors, which means that they disrupt how hormones function in the body," Merrill said. "That can mean all kinds of things, like how you grow, reproductive success — basically how your body functions. So if you're mimicking these chemicals, then the outcomes of those processes change.”
The next step for Merrill is figuring out what impact this has on these animals’ bodies, a study currently underway.