Microplastic rain down on even distant mountain peaks, a new study has revealed, with winds having the capacity to carry the pollution "anywhere and everywhere".
The researchers were astounded by the amounts of microplastic that fall from the sky into a presumably untouched place like the French stretch of the Pyrenees. Scientists now find microplastics everywhere they look; in rivers, the deepest oceans and the lands around the world.
Other recent studies have found microplastics in agricultural lands near Shanghai, China, in the Galápagos Islands, on the UNESCO World Heritage List and in rivers in the Czech Republic. People and other animals are known to consume the small plastic particles through food and water, but the potential health effects on humans and ecosystems are not yet known.
But all the pockets of the pollution mean that it has to be taken very seriously, says Steve Allen, at the EcoLab Research Institute near Toulouse, who led the new work in the Pyrenees: "If there is going to be a problem, it will be a very big problem. I do not think there is an organism on earth that is immune to this. "About 335m tons of plastic are produced every year – while being broken extremely slowly, it can be broken down into smaller and smaller pieces. Microplastic pollution in rivers and oceans is now well known, but only two previous studies have looked at its presence in the air, one in Paris, France and another in Dongguan, China. Both found a stable case of particles.
The new study, published in Nature Communications, is the first to show that microplasty rains as hard in remote environments and that it can travel over great distances through wind. The team gathered samples from high altitudes in the Pyrenees which were far from sources for plastic waste – the nearest village was 6 km away, the nearest town 25 km, and the nearest town 120 km.
On average, they found 365 plastic particles, fibers and films deposited per square meter each day. "It's amazing and worrying that so many particles were found," Allen says.
"It is comparable to what was found in central Paris and Dongguan, and there are megacities where much pollution is expected," said Deonie Allen, also at EcoLab and part of the team. "Because we were at the top of a remote mountain, and there is no near source, there is potential for microplastic to be everywhere and everywhere."
The level of plastic particle rain correlated with the wind strength and the analysis of available data showed that the microplasty could be transported 100 km in the air. However, modeling indicates that they can be worn much longer. The Saharan desert pond is already known for carrying thousands of miles of wind.
The most common microplastics found were polystyrene and polyethylene, both of which are often used in disposable packaging and plastic bags. The samples were collected in the winter and it is possible that even more microplastic can fall in the summer, when drier weather means that particles are more easily lifted from the ground by the wind.
Microplasty has been shown to damage marine life when it is wrong for food and was found in all marine mammals studied in a recent British study. They were revealed in 2017 to have polluted tap water around the world and in October to have been consumed by people in Europe, Japan and Russia.
Many researchers are concerned about the potential health effects of microplastics, which easily absorb toxic chemicals and can be harmful bacteria, with some suggesting that people are breathing the particles. The new research shows that microplasty can remain airborne.
"When you get into particles in the respiratory size, we don't know what they are doing," says Deonie Allen. "It's a very big unknown, and we don't want it to end up like asbestos." Plastic fibers have been found in human lung tissue, with the researchers suggesting that they are "candidate agents that contribute to the risk of lung cancer".
Professor Stefan Krause of the University of Birmingham, UK, and not part of the team, said that the new Pyrenees research was convincing: "These results certainly mark the need for more detailed studies."
"Frankly we are just at the beginning of the understanding [microplastic pollution]" he said. Krause leads a project called 100 Plastic Rivers, which will produce the first systematic, global analysis of microplasty in freshwater ecosystems. He said the particles present a number of potential hazards, from affecting soils and food production and transporting toxic chemicals and microbes far and wide.