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It's Raining Plastic

by Rudy Sanchez on 06/16/2020 | 3 Minute Read

By now, most of us have heard of the immense amount of plastic that has reached the world’s oceans. However, a new study published in the journal Science has found that microplastics—defined as less than 5mm in length—don’t just end up in the sea. These small particles can not only travel through the air, but they can get carried away by the rain onto far-flung and otherwise pristine land.

These particles come from larger discarded pieces of plastic, or they shed from clothing made of synthetic material like polyester. Additionally, these bits can come in the form of microbeads, small polyethylene plastic pieces added to beauty and cleaning products as exfoliators and scrubbers. 

Scientists have also started to distinguish these small particles from even tinier pieces of plastic. Dubbed nanoplastics, these snippets are less than 100 micrometers in length or a tenth of a millimeter, and they present a challenge to researchers, as you can't measure them with conventional instruments. The extent of this plastic distribution in the Earth's atmosphere is also unknown, as well as its impact on the environment.

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Researchers set out to measure the microplastics that end up in protected areas of the Western United States by collecting dry samples in the air and wet samples from rainfall. The group found over 1,000 metric tons of microplastic deposited over 11 protected areas, equivalent to 120 million water bottles over just 6% of the entire country. Most of the microparticles collected were synthetic polymers, two-thirds of particles collected in wet samples, and 70% obtained in dry samples were composed of fibers from clothing made from materials such as polyester.

A cause for alarm is how easily plastic can travel from source areas like city centers to far-flung and non-inhabited parts of the world like the Arctic and French Pyrennes. Smaller fibers and particles can be swept up from these areas by the wind, while larger particles can get distributed via rainfall.

Plastic can take centuries to decompose, and while we know that larger pieces of plastic can harm wildlife, microplastics can be even more pernicious. Small organisms like plankton, a source of food for many other species, have been found to have ingested these tiny plastic bits, and it works its way up the food chain to bigger animals, including humans. There are growing concerns about the effects of microplastics on human health, and while we know that they can cause accelerated human cell death, there are also worries about these detrimental particles impacting the soil and their surrounding ecosystems.

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Photo of microplastic beads and fragments by Janice Brahney, Utah State University.

Recycling has not been the remedy that can solve the plastic pollution crisis some have hoped. Even with widespread education and initiatives to make it easier, less than 10% of plastic is collected and turned into new items.

Unlike other kinds of pollutants that travel via air and rain, such as sulfur dioxide and nitrogen oxide, microplastics can’t easily be filtered or collected. Barring a technological deus ex machina, the amount of microplastic in the environment will only balloon unless plastic use, especially in single-use applications, is significantly curtailed.