Bottlenose Dolphins in Sarasota Bay and Barataria Bay Exhale Microplastic Fibres

Bottlenose dolphins in Sarasota Bay, Florida, and Barataria Bay, Louisiana, are breathing out microplastic fibres, our new research in the journal PLOS One has found.

Minute fragments of plastic have reached every part of the Earth – from land and the atmosphere to clouds.

An estimated 170 trillion pieces of microplastic are thought to be present in the oceans alone. Studies worldwide have shown that people and wildlife encounter microplastics chiefly through food and drink, but also by inhaling them.

Our research showed that the microplastic particles breathed out by bottlenose dolphins (Tursiops truncatus) have a chemical make-up similar to particles found in human lungs. It remains unclear whether dolphins experience greater exposure to these pollutants than humans.

Why it matters

For people, inhaling microplastics can trigger inflammation in the lungs. This may contribute to tissue damage, excessive mucus, pneumonia, bronchitis, scarring and potentially cancer. Because dolphins inhale comparable plastic particles, they could face similar lung health problems.

Research has also found that plastics contain chemicals which can affect human reproduction, cardiovascular health and neurological function. As dolphins are mammals, microplastics could potentially create these same health risks for them.

With life spans of several decades and a position at the top of the food chain, bottlenose dolphins help researchers assess how pollutants affect marine ecosystems – as well as the associated health risks for people living along coastlines. This work matters because more than 41% of the world's population lives within 62 miles (100 km) of a coast.

What is still unknown about microplastics in dolphin breath

Scientists estimate that the oceans hold many trillions of plastic particles. These enter the sea through runoff, wastewater and particles settling from the air. In turn, ocean waves can send the particles back into the atmosphere.

Indeed, bubbles bursting through wave action may emit 100,000 metric tons of microplastics into the air annually. As dolphins and other marine mammals breathe at the water's surface, this could make them particularly susceptible to exposure.

Places with larger human populations generally have more plastic. However, this relationship does not always apply to minute plastic particles in the air. Airborne microplastics occur not only in densely populated locations but also in undeveloped areas.

We identified microplastics in the breath of dolphins from both urban and rural estuaries. However, we do not yet know whether the quantity or kinds of plastic particles differ substantially between these habitats.

How we carried out the research

We obtained breath samples from wild bottlenose dolphins during catch-and-release health assessments undertaken with Brookfield Zoo Chicago, the Sarasota Dolphin Research Program, the National Marine Mammal Foundation and Fundación Oceanogràfic.

During these short, permitted examinations, we positioned either a petri dish or a customised spirometer – an instrument used to measure lung function – over the dolphin's blowhole to capture exhaled breath samples. In our colleague's laboratory, we used a microscope to look for tiny particles with plastic-like features, including smooth surfaces, bright colours or fibrous forms.

As plastic melts under heat, we used a soldering needle to assess whether the suspected fragments were plastic. Our colleague then confirmed that they were plastic using Raman spectroscopy, a specialist technique in which a laser produces a structural fingerprint that can be compared with a particular chemical.

Our findings underline both the scale of plastic pollution and the exposure experienced by other living organisms, including dolphins.

Although the consequences of inhaled plastic for dolphins' lungs remain unknown, people can help tackle microplastic pollution by using less plastic and helping to stop further plastic entering the oceans.

Leslie Hart, Associate Professor of Public Health, College of Charleston and Miranda Dziobak, Instructor in Public Health, College of Charleston

This article is republished from The Conversation under a Creative Commons licence. Read the original article.