Microplastics are everywhere…
From bustling intersections to pristine lakes and ponds. And the small strands made up of plastic have even been found inside the human body.
Last year, one of the world’s leading medical academic journals – The Lancet – published a special edition that called plastics a “grave, growing and under-recognized danger to human and planetary health.”
Much of the research into microplastics so far has tried to answer the question of just how much is out there…
“And in 2020 or there about, it became pretty apparent that microplastics were going to become an important contaminant,” says Jerry Miller, a professor of environmental science at Western Carolina University. “And they’d been studied in marine environments since the 1970s, but there’d been very little work done on microplastics in freshwater systems, particularly within rivers.”
So, Miller and other researchers started looking into microplastic levels in headwaters; that’s essentially where a river starts. Miller says, as you might expect, urban areas, which typically have more trash, pollution and cars with rubber tires – a source of microplastics – had input into river systems.
“But one of the things that surprised us is that we could go to headwater areas, small basins that were 99% forested, limited access for humans and we were still getting really high concentrations. And, in fact, the concentrations we were finding kind of averaged around 10 particles per liter, and these were some of the highest concentrations that had been measured globally,” he says.
That led Miller and others to a hypothesis…
“One of our conclusions was that those particles are probably coming from atmospheric deposition.”
Thanks to some funding from the North Carolina Water Resources Research Institute, Miller and colleagues at the Highlands Biological Station, a research facility also run by Western Carolina University, and Virginia Tech were able to put up sampling units in the western part of North Carolina to get an idea of how much microplastics were making their way into river systems there – whether that be through runoff into the water itself or the atmosphere.
Jason Love is the associate director of the Highlands Biological Station, and he says those monitors are few and far between across the country, especially when it comes to air monitoring.
“One of the reasons is because it’s not a criteria pollutant that the EPA is mandated to measure. So, they’re mandated to measure things like lead in drinking water and sulfur dioxide in the air. But microplastics – there are no regulatory rules regarding what the concentrations are, even in drinking water.”
The team’s monitors were already in the field and collecting data when Hurricane Helene was set to arrive in the fall of 2024…
“Literally, it was a perfect storm of we already had our samplers out,” says Austin Gray – an associate professor of biological science at Virginia Tech. “They’re set up to collect wet and dry deposition, and they happen to be in the area in Western North Carolina where the biggest impact of Helene was.”
That “perfect storm” gave the research team a chance to study the impact of microplastic deposition from a hurricane in an understudied area and to collect data before, during and after, which Gray says was practically unheard of in this part of the world before their study.
“One of our conclusions was that those particles are probably coming from atmospheric deposition.”
“But a lot of the work within hurricanes and typhoons is always in Asia, it’s always in the eastern parts of the world, where in the United States, or at least within the Western Hemisphere, the only study that had been done was in 2021, Hurricane Larry,” Gray says. “And even that study was focused within Newfoundland. And that was a Category 1 storm. So, even then, it’s like, ‘Ok, well, this is a Category 4, this is a huge storm event’ and it had such an impact on society within the Southeast United States.”
The results, as you can probably guess, were astounding…
“But the atmospheric samples were the samples I was really interested in just because of the amount of rainfall – I wanna say it was trillions of gallons of rainfall hit Western North Carolina. It’s an area that wouldn’t normally see that, it was a historic storm,” Gray says. “And so, we were basically trying to figure out, ‘Ok, well, how does a microplastic footprint or how does the detection or the quantification of microplastics change with that?’”
“At Highlands, during those days of the storm, we were getting a total of over 10,000 microplastics per square meter from the storm,” says Jason Love. “And in that entire year, so from November 2023 to November 2024, we calculated roughly 55,000 particles per square meter for the whole year. So that 10,000 represented close to 20% of our annual total just during those three days.”
Jerry Miller at Western Carolina says the atmospheric deposition was about three to 22 times higher during Helene than during times prior to the storm. There was an interesting wrinkle in the data when it came to the water running in streams, though.
“Concentrations actually decreased,” he explains. “And the reason for this is that we essentially diluted what we’d normally find in the stream system. So, even though we were adding more atmospheric material to it, we just got so much water in the stream channel that those concentrations were lower during that particular flood event. Now, there’s another way we can also look at microplastics in streams, and we refer to that as load – and that’s essentially a measure of the number of particles that pass a point in the stream per unit of time. And, we normally do this as particles per hour. And in that case, Helene really generated some enormous values. On a typical flood event, we might find somewhere between 50 and a few hundred million particles that pass a point in the stream. During Helene, at one site, we got over 70 billion particles being moved downstream per hour. So, even though the concentrations went down, the total transport of microplastics was just enormous.”
Another very interesting part of the study was what occurred with microplastic levels both in the water and air in Western North Carolina after Helene passed. The monitors continued to detect high levels of the substance even though the rain from the storm had ceased.
“And what we believe what happened is after the storm and the rainfall stopped – because the storm occurred before leaf fall, but as leaf fall occurred, but also wind – we saw that there was release of these microplastics from the surface of the leaves down to below the canopy, to the understory,” Austin Gray tells me. “And that’s where our samplers would capture the fallout from that, and that’s why we saw this increase in dry deposition microplastics. That these particles weren’t so much stuck in suspension in the air, but they were deposited in these vegetative structures that then were released as they fell from the trees or from wind and then they deposited.”
The monitors and the team’s extraction methods have a specific resolution as well, so Gray tells me that it’s likely the amount of microplastics deposited by Hurricane Helene was even greater than what they measured, as material smaller than what the team was looking for was unaccounted for.
While working on this story, I’ve learned this is an important area of study because microplastics don’t degrade quickly. They hang around, and much of the material deposited from Helene is likely still there… To a much lesser extent, Gray tells me that this same kind of deposition can happen with any rain event, including your average, summer thunderstorm. Long story short, this is a universal problem that won’t go away anytime soon.
Gray, Love and Miller are going to continue monitoring the streams, rivers and air within Western North Carolina to get a better picture of the evolving microplastics story.
That’s important because, as I mentioned before, most research up until this point has tried to grasp just how much of the stuff is out there. We’ve barely scratched the surface of potential impacts to our health and the health of our environment. But understanding the baseline levels is vital before trying to answer that question.
“To me, the question becomes where does the risk kick in? How does environmental exposure associate to risk outcomes? Because I think that’s what everybody wants to know,” Gray says. “They want to know, ‘Well, if I’m exposed to microplastics and it’s in my body, well what’s my risk of developing cancer? What’s my risk of developing some disease tied to microplastics?’ And right now, we’re able to show associations, but I don’t think we can say anything can be, “Oh, it’s from microplastics.’ But that requires more research. I don’t think people leave their homes and think, ‘Oh yeah, there’s microplastics in the air.’ But they’re there! And it’s not saying you’re going to die because of it. But it’s more so saying we should investigate as much as we can to understand, ‘Ok, how much within a certain area? How does that change when a storm happens? What happens after a storm? Are the levels still elevated? How long does it take to get back to baseline? What is baseline?’ And so, it was one of those things where monitoring, to me, is important.”
Jason Love at the Highlands Biological Station says the hope for this study and others like it is to provide information to the public and those in power to hopefully better inform decisions about any future policies guiding the regulation and research of microplastics.
“We find a lot of blue fibers in our samples. And we did some research, we looked at the fashion literature – and blue is the most popular color in fashion,” Love says. “So, we can’t blame this on the bears… This is a human caused problem, and until we have serious discussions about plastic production and single-use plastics and fast fashion – the problem is not going to go away. In fact, it’s actually probably going to get worse because there’s this tension between growing the economy and meeting shareholder expectations. And either the public or the environment pays the cost.”
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