A new study has provided the first evidence that microplastics are accumulating in bird lungs.
Birds have long been used to give early warnings of environmental risks. The absence of birdsong was used in the evocative title of Rachel Carson’s 1962 book Silent Spring, and for more than a century miners carried caged canaries to warn of carbon monoxide – a practice that ended in UK coalmines only in 1996.
Prof Yongjie Wu, from Sichuan University, who led the study said: “Birds are highly mobile, ecologically diverse and have unique respiratory systems that make them vulnerable to airborne pollutants. We aimed to assess the micro and nanoplastic contamination in bird lungs and evaluate their potential as bioindicators for airborne plastic pollution.”
The researchers analysed the lungs of birds from 51 species. All had been killed as part of a programme to minimise aircraft bird-strikes at China’s Chengdu Tianfu international airport. Microplastics were found in every bird’s lungs.
Shane DuBay of the University of Texas at Arlington and part of the research team said: “The result that surprised me the most was the widespread contamination in all species that we sampled, regardless of body size, habitat preference and feeding habits.”
Microplastics were found in all the species studied, with an average of 416 particles in every gram of lung tissue. Terrestrial birds had a greater burden of microplastics compared with aquatic birds, and large birds than smaller ones. The greatest burdens were found in carnivorous and omnivorous birds, suggesting habitat and feeding were important exposure routes – foraging in polluted areas, for example.
The researchers found fibres, films and pellets from 32 different types of plastic including polyethylene, polyurethane, polyvinyl chloride (PVC) and butadiene rubber, which is, as Wu explained, widely used in tyre manufacturing. “Tyre wear from aircraft/ground vehicles and nearby roads could release butadiene rubber particles into the air, but further source-tracking studies are needed to confirm this.”
Although tyre wear is often overlooked as a source of microplastics, it is thought to be responsible for between 5 and 28% of plastic entering the oceans.
DuBay continued: “This widespread contamination highlights the pervasive nature of airborne plastic pollution. This is a global problem, like plastics in our oceans.”
Previous studies have found microplastics in the air in remote parts of the Alps and in megacities in China, in Paris and London.
In 2018, Dr Stephanie Wright from Imperial College London, set up an air sampler on a rooftop near London’s Somerset House. In four weeks of sampling, she found 15 types of petrochemical-based polymers.
Wright, who was not involved in the bird-sampling study, said: “This new research on bird lungs highlights the pervasiveness of microplastic pollution, which we now know contaminates the atmosphere, and clearly presents an issue for both animal and human health.
“We’ve observed microplastic particles in atmospheric fallout in London, from both outdoor and indoor environments. You can’t clean it up, so it is all about stopping it at source. The fact that these are persistent materials is a cause for concern, especially if they are accumulating in the body.”
