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plastic nurdles

Citizen scientists are seeing an influx of microplastics in the Ohio River

Microplastics are increasingly found in fresh water across the country. Researchers are just beginning to understand the consequences.

PITTSBURGH — A group of citizen scientists have observed a substantial influx of nurdles — small plastic pellets about the size of a lentil — in the Ohio River, which provides drinking water to more than five million people.


“In the last few months, we’ve seen a huge surge in nurdles,” James Cato, a community organizer at the Mountain Watershed Association, told Environmental Health News (EHN) in November. “Where we’ve normally been detecting about 10 nurdles per sample, we’re now seeing 100.”

Cato and other citizen scientists have regularly conducted “nurdle patrol” since 2020, taking to the river in boats to collect nurdles from water and sediment samples. Their goal is to establish a rough baseline for how many and what types of nurdles are in the water before Shell opened its massive new plastics plant along the Ohio River in southwestern Pennsylvania.

But these particular nurdles represent just a tiny fraction of the microplastics plaguing the Ohio River and other freshwater bodies across Pennsylvania and the country. Broken down pieces of plastic packaging, bottles, or bags, and plastic fibers used in synthetic textiles (like nylon) — basically any pieces of plastic that are less than five millimeters long — are also considered microplastics.

What’s happening with the influx of nurdles in the Ohio River exemplifies how hard it is to track down the sources of such pollution and determine who is responsible for cleaning it up. And amid the confusion, scientists are just beginning to understand the consequences to wildlife and human health.

“When I started looking into this a couple years ago, freshwater environments weren’t really on the radar because most research on microplastics had been focused on marine environments,” Lisa Emili, a researcher and associate professor at Penn State University Altoona, told EHN. “That’s starting to change as we increasingly recognize that freshwater environments have the ability not only to transport microplastics, but also to accumulate them.”

Tracking down the source of plastic nurdles

Plastic nurdle pollution

A leaf along the Ohio River. Citizens scientists have seen an influx of the pollution.

Credit: James Cato

Plastic nurdle pollution

Nurdles found in the Ohio River by Mountain Watershed Association and Three Rivers Waterkeeper

Credit: James Cato

Shell’s plant, which came online in November, will produce up to 1.6 million metric tons of plastic nurdles every year to be used in many consumer products, including single-use plastic packaging and bags. But the influx of new nurdles showed up before the plant opened, and the nurdle patrollers think they’ve traced many of them to a different source.

“These nurdles are really tiny, about the size of a poppy seed and about an eighth the size of regular nurdles,” Cato said. That unique appearance allowed them to track a trail of them to an outfall on Racoon Creek, a tributary of the Ohio.

The outfall belongs to a company called Styropek, which manufactures expandable polystyrene pellets, or EPS — rigid plastic pellets that are later expanded with air to double their size, then used to manufacture insulation and packaging products similar to Styrofoam. According to its website, Styropek is the largest manufacturer of these pellets in North America.

“We found thousands of these nurdles downriver of Styropek’s outfall and just two upriver,” Cato said. “There were also lots of nurdles on the riverbanks — so much that it looked like snowfall, coating plants in white — and they basically formed a bull’s eye around the plant, so we’re pretty confident they’re coming from there.”

The groups first noticed the nurdles in September. As private citizens, they couldn’t investigate further without trespassing on Styropek’s property, so they alerted regulators at the U.S. Environmental Protection Agency (EPA). About a month later, the EPA referred them to the Pennsylvania Department of Environmental Protection (PA DEP), at which point the groups filed a complaint with that state agency and the Pennsylvania Fish and Boat Commission to ask them to investigate.

Their contact at the Fish and Boat Commission wanted to help, but didn’t think they had legal jurisdiction to do so. Jamar Thrasher, a spokesperson for the Department of Environmental Protection, said the agency had performed an inspection at Styropek about a week prior to receiving the complaint, and “found nothing floating near the facility’s outfall or in the stream and identified no violations.” Still, in response to the complaint, he said the agency “requested that Styropek develop and integrate a more expansive plastic pellet/nurdle housekeeping plan to prevent potential discharge through any outfalls.”

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The groups doing nurdle patrol alerted Styropek to the problem. In response, the company hired an environmental consultant, verified that they'd had an accidental release of plastic nurdles into Racoon Creek, and began working to identify causes of the spill and plan remediation efforts. In late December, the Department of Environmental Protection issued a notice of violation to Styropek for the nurdles.

"We are working closely with [the Department of Environmental Protection] and are actively investigating, and we are committed to implementing necessary corrective actions," Styropek spokesperson Danielle Kephart told EHN. "We remain dedicated to the health and safety of the communities in which we operate, and I plan on keeping Three Rivers Waterkeeper updated on our investigation as I am able."

This incident proves that the nurdle patrollers are doing essential work — and indicates that without their vigilance, releases of plastic nurdles into waterways would likely go unnoticed by regulatory agencies.

Nurdle pollution is largely unregulated. There are no international regulations on it, but in 2022 the United Nations resolved to create an international treaty aimed at restricting microplastic pollution in marine environments. A draft of the rule is expected to be complete in 2024.

In the U.S., no agency is charged with preventing or cleaning up nurdle pollution — nurdles aren’t federally classified as pollutants or hazardous materials, so unlike oil spills or other toxic substances in waterways, the Coast Guard doesn’t clean up nurdle spills.

Most state governments don’t have rules in place related to nurdle monitoring or cleanup, and in other parts of the country, it has sometimes been unclear who bears responsibility for regulating its pollution, resulting in an alarming lack of cleanup when spills do occur.

Pennsylvania Department of Environmental Protection spokesperson Lauren Camarda said nurdles are prohibited from entering waterways under Pennsylvania’s Clean Streams Law and the Solid Waste Management Act, both of which should enable the agency to hold polluters accountable for cleaning up nurdle spills.

Microplastics pervasive in fresh water 

Plastic pollution in oceans has gotten lots of attention, but researchers are now discovering that microplastic pollution in fresh water is also pervasive.

A study published by the nonprofit environmental advocacy group PennEnvironment in October found microplastics in all 50 of the “pristine” Pennsylvania waterways the group sampled — all of which are classified by Pennsylvania’s Department of Environmental Protection as “exceptional value,” “high quality” or Class A trout streams.

Research on microplastics in fresh water across the U.S. is still limited, but scientists have found microplastics nearly everywhere they’ve looked, including many waterways that feed the Great Lakes and the lakes themselves, rivers throughout Illinois, and California’s Los Angeles and San Gabriel Rivers.

Microplastics can kill fish and other wildlife that ingest them by making their stomachs feel full when they’re not, but emerging research suggests they can also enter fish through their gills or skin, poison their flesh and travel up the food chain, which has implications for other types of wildlife and human health.

“Microplastics piggyback other pollutants like bacteria, heavy metals, endocrine-disrupting chemicals and PFAS [per-and polyfluoroalkyl substances, a.k.a. ‘forever chemicals’],” Emili said. “We know they’re not good for us, but unlike other pollutants, we don’t even know how to set maximum daily loads for microplastics to avoid health consequences because they come in all different sizes, chemical compositions and levels of toxicity.”

Nurdles account for a large proportion of microplastics in waterways — by weight they’re the second-largest source of micropollutants in the ocean (after tire dust).

Microplastics in human blood

microplastics human health

"The study that really scared everyone found microplastics in human blood."

Credit: Oregon State University

Microplastics have been found virtually everywhere on the planet — from the top of Mount Everest, the highest elevation on Earth; to the Marianas Trench at the very bottom of the Pacific Ocean; in fresh rain and snow, in the cells of fruits and vegetables, in the bodies of animals and humans and even in placentas and newborn babies.

“But the study that really scared everyone found microplastics in human blood,” Emili said. That study, published in May 2022, was the first to detect microplastics in human blood. They showed up in 80% of people who were tested.

“This means we’re starting to see not just ingestion of microplastics by animals and people, but also absorption of really, really small microplastics at a cellular level.”

It’s not yet entirely known how having microplastics in our bodies and blood impacts our health, but other research suggests the pollution can damage human cells, while other scientists have hypothesized they could increase cancer risk and cause reproductive harm, among other health problems. And we do know that some of the toxic substances that piggyback on microplastics, like heavy metals, PFAS and endocrine-disrupting chemicals are associated with numerous health problems including higher cancer risk and reproductive harm.

Researchers are also worried that an influx of microplastics in fresh water has the potential to disrupt natural carbon cycles, further fueling the climate crisis, according to Emili.

“If we’re substituting plastics for something like natural sediment, microbes may gravitate toward them more than natural sources, which could upset the larger carbon sequestration cycle,” she explained. “We don’t know for sure, but this is also something we really need to look at.”

Plastic nurdle libraries

The groups doing nurdle patrol in the Ohio River are working with researchers at Penn State University to build a “nurdle library” — an index of the various nurdles they’ve collected with information about where each one came from and what it’s made of.

These libraries could help them quickly identify large quantities of nurdles they spot down the line. But there are many potential sources for nurdles spills, and identifying where each piece of plastic came from poses its own challenges.

“Nurdles start to degrade once they’re in the environment,” Emili explained. “The way they started out their life looking, chemically, is not necessarily what they’ll look like after degrading. That makes it harder to say for sure where they came from.”

In May of 2022, a train derailment outside of Pittsburgh spilled approximately 120,000 pounds of plastic nurdles into the Allegheny River (along with approximately 5,723 pounds of oil). The Pennsylvania Department of Environmental Protection oversaw cleanup efforts conducted by contractors for Norfolk Southern Corporation, the owner of the rail line responsible for the spill.

The company estimated that 99% of the nurdles were recovered, according to the state agency, but the nurdle patrollers say they still regularly come across pieces of plastic they recognize from that spill. The company hasn’t yet been fined for the accident, and the activists worry that enforcement related to releases of nurdles is inadequate to deter them.

“The cleanup of this incident is ongoing and [the Department of Environmental Protection] DEP is reviewing revised plans for how the operator will clean up remaining pellets,” the agency’s spokesperson Lauren Camarda told EHN. “The remediation and DEP’s compliance and enforcement activities related to this incident are ongoing, and, as such, DEP has not yet assessed a civil penalty.”

A recent report by international conservation organization Fauna & Flora International noted that nurdle pollution isn’t something that can be controlled through individual consumers, and called for a “robust, coordinated regulatory approach from industry, governments, and the International Maritime Organization.”

“So far we haven’t seen satisfactory enforcement even for egregious violations,” Evan Clark, a boat captain and nurdle patrol leader with Three Rivers Waterkeeper, told EHN. “We’re going to keep an eye on Styropek, but for us the bigger picture is making sure we can get our regulators to do meaningful enforcement around plastics in our waterways.”

Editor's note: This story was updated on 1/13/23 to add a response from Styropek.

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