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Microplastics are in our food and water.
They’re in the air we breathe.
They’re even in the dust that collects on the furniture at home.
And new research from the University of New Mexico reveals that these substances are accumulating in our bodies as well – as much as a teaspoon’s worth in our ains.
While much is still unknown about these ubiquitous particles and their impact on the environment and human health, scientists in South Carolina and around the country are working to learn more.
Plastic is an oil-based polymer, and microplastics are tiny particles of plastic that measure between 1 nanometer and 5 millimeters wide, or between a fraction of the width of a human hair to the width of a wedding band, according to the United Nations Environment Programme.
Most come from “the slow disintegration of larger plastic products, including plastic wrap, take-away containers, polyester clothes, tires, paint, and artificial turf,” the agency reports. But they’re also found in personal care products.
In fact, says Dr. Geoffrey Scott, professor and chair in the Department of Environmental Health Sciences at the University of South Carolina’s Arnold School of Public Health, they’re everywhere.
The Organisation for Economic Co-operation and Development estimated that 2.7 million tons of microplastics “seeped into the environment in 2020” – an amount that’s expected to double by 2040.
“The biggest source is the air you breathe. You can hardly avoid being exposed,” Scott said. “And oysters have one of the higher levels of microplastics. If you eat an oyster, you’re eating 15 to 18 microplastics per oyster.”
Plastics are such a difficult problem because they’re light-weight and so durable, says James Sternberg, assistant professor in Clemson University’s Department of Food, Nutrition, and Packaging Sciences.
“Paper is biodegradable. It will eventually … biodegrade in oceans,” he said. “The problem with plastics is … they just end up getting smaller and smaller in size … and just taken up into the food system.”
Scott’s research has focused on seafood.
Formerly a federal lab director for the National Oceanic and Atmospheric Administration for 20 years, he and other researchers, including Dr. John Weinstein of The Citadel, found that microplastics from tires in roadway runoff wind up in shellfish harvest areas, among other places.
In fact, a study from the 1990s revealed that 70 percent of the runoff from a bridge on the Isle of Palms flowed into shellfish harvest areas, runoff that was dominated by tire plasticizers, he said.
Scott says his team has done other studies looking at tire wear particles and estimates that for every algae plant in the ocean today there are six microplastic particles.
Another project Scott and Weinstein looked at involved grass shrimp in a tidal creek in South Carolina and found that they accumulated a variety of microplastic particles.
“These shrimp are used widely as an indicator species,” he said. “And 80 percent of the fish in the South Atlantic that are commercially important or recreationally important spawn offshore and their larvae swim into the estuary to mature and eat these shrimp.”
In addition, he said, ocean fish need to take in seawater several times their body weight every day, which is another route of exposure to microplastics besides feeding, Scott said.
So when you eat those fish, you’re also eating microplastics, he said.
Moreover, he said, plasticizers – like those that leach out of tires and plastic water bottles – are causing kills of coho salmon juveniles in Puget Sound.
These plasticizers can kill the salmon in the parts per trillion levels, and runoff contains much higher levels than that, he added.
Studies reveal that the percentage of microplastics in fish mirrors the highest produced plastic in the world – polyethylene – which is used in plastic bags, shrink wrap, and bottles, Sternberg said.
But microplastics are even found in the laundry water from washing polyester clothes and the lint from those clothes in the dryer, he said.
“It’s almost everywhere you look,” he said. “Even sod. It has plastic netting. And it’s in the ground and … doesn’t degrade for hundreds and hundreds of years. And every time you mow or walk on it, it’s fragmenting. And as the sun beats on it and oxidizes it, it breaks off.”
While the human health impacts of ingesting microplastics are largely unknown, Scott says they attach to your cholesterol and clog your arteries.
In medical scans of heart plaque, he said, polyethylene was found in 60 percent of the patients and polyvinylchloride was found in 12 percent. And patients with microplastics in their arteries were four times more likely to experience severe cardiovascular outcomes – including heart attacks, strokes or death – compared to those whose arteries did not contain microplastics.
And textile microfibers at very low concentrations caused shrimp to beat their heads against the sides of the containers they were housed in, leading to speculation that microplastics may be contributing to hyperactivity, he said.
“It’s the equivalent of a human banging his head against a wall,” he said. “So this could end up affecting populations.”
There’s also a question about whether microplastics may contribute to obesity because they accumulate in the lipids, Scott said.
One study found that the chemical pesticide DDT caused rats to accumulate fat, and by the third generation, the average rat was overweight by 30 percent, he said, noting that the obesity rate in the US is 31 percent today.
Stefanie Whitmire, assistant professor in Clemson’s Department of Agricultural Sciences in Georgetown at the Baruch Institute of Coastal Ecology and Forest Science, studies microplastics in the environment.
An aquatic biologist who formerly worked with the National Park Service, she began microplastics research in 2016 to see whether the parks were at risk from microplastics pollution.
Looking at water, sediments, and beach sand along the U.S. coastline, the Great Lakes, Hawaii, and Alaska, the researchers were surprised to find microplastics in some very remote areas, she said.
“But now we know from other research, it’s been found on mountaintops in Colorado, in glaciers, in the air,” she said.
“Microplastics are in storm water distribution in coastal South Carolina and in the sediment,” she added. “And we’re trying to understand how (they) … are changing the nutrient cycling in these ponds or in algal communities. Some people have shown that it changes nitrogen and carbon cycling, which could potentially change microbial communities as well.”
Whitmire is helped in her research by graduate student Morgan Chaudry and Wofford undergrad Hannah Dozier. They collect sediment samples from a variety of spots, a pond for example, which are taken back to the lab where a laser-directed infrared spectrometer is used to identify the polymers. Much of what they’ve found is from fabric fibers, she said.
Whitmire is also part of a team, led by Ph.D. student Miriam Boucher, that’s involved in analyzing the stomach contents of legally hunted alligators to get an understanding of how much microplastic they‘re ingesting and what that means for their overall health.
Alligators have been used in studies before because they live a long time and have similar reproductive and endocrine systems as humans, she said.
The main goal of Whitmire’s research is to publish their data, present it at scientific meetings and community talks, and share it with extension agents so it becomes publicly available.
It’s also added to a national microplastics database supported by NOAA, she said.
Sternberg notes that the Great Pacific Garbage Patch – a huge area of plastic twice the size of Texas in the North Pacific Ocean – is not just a patch of floating plastic bottles but includes a high concentration of microplastics. And about 50 percent of the material in it comes from fishing, like nets and lines, he said.
Microplastics have been found to accumulate in different organs, including the liver, kidneys, lungs, and the human placenta, Sternberg said. And while there isn’t a lot of research on the effects of microplastics on human health, some studies show they can cause inflammation, he added.
Sternberg is researching new biobased plastics for a variety of uses that can biodegrade. One, polylactic acid, comes from corn and is 100 percent biobased, he said. Another can degrade only in industrial composting conditions while PHAs, or polyhydroxyalkanoates, are biodegradable in home composting situations.
“Plastic is a huge problem, but it also solves a huge problem,” he said. “It extends the shelf life of food, keeps food safe, especially meat and things that can spoil.”
Meanwhile, he said, plastic contributes less than 5 percent of the impact on the environment while growing food contributes 95 percent of the impact.
So what can be done about this?
The experts say we need to think about reducing single-use plastics.
“We’re not going to get rid of plastics,” Whitmire said. “But if we can think about reducing our reliance on single-use plastics – like straws, take-away containers, cups, bottled water – it would be a start to help this problem. I carry my own bamboo utensils instead of using plastic at restaurants.”
It’s unlikely that plastic pollution can be prevented because of mismanagement of waste, among other considerations, she said. But it’s possible that there are ways to prevent microplastics from making their way into estuaries and oceans and other bodies of water that are home to fish people eat, she said.
“Some researchers in North Carolina are looking at trapping big plastic pieces in rivers and streams and removing them before they travel downstream,” she said.
Scott says society should pay attention to substances that persist in the environment and that bioaccumulate. And if that means doing away with certain products, maybe it should be done, he said.
To reduce the level of microplastics in our bodies, he recommends using a stainless-steel water bottle instead of plastic, avoiding foods known to contain microplastics, and getting regular exercise.
But even given what he knows about seafood, Scott says he eats fish – mainly herbivorous fish like tilapia, mullet, and scallops, which accumulate much less of these chemicals – at least twice a week because it reduces the risk of heart attack and stroke by 40 percent.
“I don’t know what society ought to do because it’s so complex,” Sternberg said. “One answer is everything’s local – no more global food.”
Creating safer plastics is one way to address the issue, he said, while another is finding ways to reuse plastics instead of just throwing them away. Currently, those options use a lot of energy and require billions in expensive infrastructure, he said.
One thing is certain, scientists will be looking at the problem for years to come.
“Microplastics … are in the air, the water, the food, our beverages. They’re even in beer,” Sternberg said. “They don’t dissolve or ever go away.”
The environmental website EcoWatch offers these tips to reduce microplastics exposure:
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