Scientists Have Found Microplastics in Dolphin Breath for the First Time

A research team collected samples of exhaled breath from 11 bottlenose dolphins and found something deeply worrying: tiny pieces of pollution called microplastics.

The discovery adds another odd site to a long list of places where these microscopic particles can be found. It also suggests inhalation could be a significant method of dolphin exposure to plastic chemicals, which could possibly be harmful to their health, though more research is needed. The team presented their findings in a study published in the journal PLOS ONE last week.

“Finding microplastics in the exhaled breath of dolphins highlights how extensive environmental microplastic pollution is,” say co-authors Leslie B. Hart, an environmental researcher at the College of Charleston, and Miranda K. Dziobak, a biochemist at the University of South Carolina, in a joint interview with PLOS ONE. “Because of their large lung capacity and deep breaths, we are worried that breathing in microplastics may damage their lungs.”

Experts have found microplastics virtually everywhere, from breast milk to Mount Everest—even in areas that might seem “untouched” by urbanization. The pervasive contamination is also facilitated by wind, which studies show can blow microplastics across vast distances.

Microplastics have been linked to health complications, including oxidative stress and inflammation in humans and rodents, per a statement from the journal, with ingestion being the major exposure method in both humans and wildlife. Inhaling microplastics has also been noted as potentially damaging to human lungs and airways, with experts suggesting more research is needed to have a clearer idea of the impacts. And while “microplastic inhalation in humans is a budding field,” Hart tells the Guardian’s Karen McVeigh, “there have been few studies in wildlife.”

Dolphins are frequently studied for pollution research because of their presence in both remote regions and heavily developed areas all over the world. This makes them “bellwethers of exposure to pollution and other environmental hazards,” writes the New York Times’ Hiroko Tabuchi.

The scientists thus conducted a catch-and-release health assessment on five bottlenose dolphins in Sarasota Bay, Florida, and six bottlenose dolphins in Barataria Bay, Louisiana. They held a petri dish or a customized spirometer, which measures lung function, above each dolphin’s blowhole as the animal exhaled. The team also collected samples of the surrounding air to make sure anything they captured from the dolphins was truly from their exhalation and not simply airborne.

Back in the lab, they checked their samples for microplastics using microscopes, keeping an eye out for particles with smooth surfaces, bright colors or fibrous shapes, as Hart and Dziobak write for the Conversation. They then used a soldering needle to see if these identified particles melted like plastic. The final piece of evidence came with Raman spectroscopy, a technique that uses a laser to identify specific chemical components of a material.

Overall, they identified 54 bits of microplastic across all the samples of exhaled dolphin breath, per the study. The microplastics included polymers—chemical compounds that form plastic—such as polyethylene terephthalate (PET), a component of plastic packaging like water bottles. They also identified poly(methyl methacrylate), known as PMMA or acrylic, and polyester, which is shed from our clothing items when we wear or wash them.

“Just as we suspected, dolphins are breathing in microplastics,” Hart and Dziobak say in the PLOS ONE interview. “Not only did we find that many of the dolphins were exposed to these chemicals, but their levels were higher than those found in humans.”

We already know that there are trillions of microplastics in our oceans. The scientists suspect that dolphins and other marine mammals might be particularly vulnerable to the microplastics tossed into the air by waves when they surface to take a breath.

Shannon Gowans, a behavior ecologist at Eckerd College and head of its Dolphin Project who was not involved in the new research, tells the New York Times that the study is concerning. She adds that storm surges, like the ones that occurred during the recent hurricanes in Florida, also fill the ocean with untreated water and debris, which undoubtedly cause a spike in microplastics.

Nina Wootton, a marine ecologist at the University of Adelaide in Australia who also was not involved in the study, tells New Scientist’s James Woodford that she would like to know how the microplastics affect dolphins. “Dolphins are often an indicator of marine ecosystem health, so this finding supports the fact that microplastics really are ubiquitous,” she tells the publication.

Further studies are needed to determine what the health effects might be for the mammals, which could in turn hold implications for the health of people living near coasts.

“We hope these findings will inspire people to reduce their own plastic consumption,” Hart and Dziobak say in the PLOS ONE interview, “for the health of themselves and the health of the dolphins.”

Margherita Bassi | READ MORE

Margherita Bassi is a freelance journalist and trilingual storyteller. Her work has appeared in publications including BBC Travel, Discover magazine, Live Science, Atlas Obscura and Hidden Compass.