New UToledo Study Examines Threat Of Tiny Airborne Plastics

More than 20 million pounds of plastic waste accumulates in the Great Lakes every year.

While crusty water bottles, fraying cigarette butts and tangled knots of fishing line littering the shoreline may be the most visible evidence of that pollution, a bigger concern is the tiny plastic particles that we cannot easily see.

“As this plastic waste ages, gets battered by lake currents and is exposed to UV radiation, it starts to break down into smaller and smaller pieces,” said Dr. David Kennedy, a professor of medicine at The University of Toledo. “Those nanoplastics are a really worrying environmental and human health risk.”

Kennedy and research partner Dr. Steven Haller study environmental determinants of health, with a particular focus on Lake Erie. Much of their recent work has centered on the toxins produced during harmful algal blooms, including an ongoing assessment of how aerosolized microcystin affects human health in those living or working near Lake Erie.

New research from their lab takes a similar look at the risk posed by airborne nanoplastics, which are defined as particles less than 1 micron in size. To appreciate just how small that is, the thickness of a human hair averages between 50 and 100 microns. Microplastics, by comparison, are defined as particles between 1 micron and 5 millimeters in diameter.

Using a high-tech model of the human airway made from donated human lung cells, Kennedy and Haller simulated an acute exposure to aerosolized polystyrene nanoparticles — three minutes per day for three days — to assess how our lungs react to breathed-in plastic particles.

They found an immune response that was highly dysregulated.

Our lungs have special, hairlike cells called cilia that work to sweep mucus and trapped pollutants up and out of the respiratory tract. The nanoplastics sent those cells into overdrive, but they weren’t effectively clearing the particles — akin to a car with its wipers on high but no water is being pushed off the windshield.

Similarly, they saw cells sending both anti- and pro-inflammatory signals.
“The presence of these nanoplastics seemed to confuse the cells,” said Haller, who is an associate professor of medicine. “The cilia are hyperactive, but they aren’t clearing anything. Inflammatory responses and immune responses need to be coordinated, but what we saw was very uncoordinated. It was a disorganized and chaotic response.”

What makes UToledo’s research unique is that, unlike studies that rely on lab-created cell lines, it broke new ground by using human lung cells directly donated by volunteers. These cells were grown in a special air-liquid interface model that closely mimics how lung tissue functions in real life, providing a much more realistic look at how our lungs might respond to inhaled nanoplastics.

The results were published this spring in the journal Antioxidants.

Part of what makes the findings important — and concerning — is the potential for those nanoplastics to serve as a delivery vehicle for other chemical cargo, such as the toxins produced during harmful algal blooms.

“We know that plastics, especially really small plastics, can be carriers for other things,” Haller said. “You have the plastic creating a confused immune response while a toxin is also present. We don’t know what the cumulative effect of that might be, particularly in someone with other pre-existing conditions.”

The UToledo researchers said their initial research lays the groundwork for additional studies that look at longer periods of exposure, as well as how lung cells respond to plastics alongside other potential toxins.

“This is early research, but I think it helps people understand plastic pollution isn’t just an environmental threat. It’s a human health threat, too,” Kennedy said. “When people understand them that way, they may be inspired to change their behavior.”

While microplastics and nanoplastics are widespread – both in and outside bodies of water – people can take meaningful steps to limit their spread and exposure. Choosing reusable alternatives over single-use plastics, properly disposing of plastic waste and selecting clothing made from natural fibers instead of synthetics all help reduce the amount of plastic entering the environment.

“Glass, which is part of Toledo’s proud history as the Glass Capital of the World, offers a durable, reusable and environmentally friendly alternative to plastic – and it’s a great way for our community to lead by example,” Kennedy said. “Even small changes in daily habits, when adopted by many, can make a real difference in protecting our waterways, air and health. By rethinking how we use plastics, we can help safeguard our air, water and health – and leave a cleaner legacy for the future.”

In addition to Haller and Kennedy, the research team included Dr. Mark Wooten, professor of medical microbiology and immunology; Dr. Andrew Fribley, associate professor of medicine; Dr. Deepak Malhotra, professor of medicine; Dr. Joshua Breidenbach, who recently completed his Ph.D. at UToledo; graduate students Benjamin French and Upasana Shrestha; and undergraduate researcher Zaneh Adya.