By Lori Olinger and Steve Ring
Last month on Earth Day, two Sierra Club Northstar Chapter organizations—the Waters and Wetlands Stewards and the Zero Waste Task Force—co-hosted a presentation about microplastics. University of Minnesota Researcher Mary Kosuth, who studies microplastics, shared some fascinating information from her work, along with insights from other scientific studies.
What are microplastics?
Microplastics are tiny pieces of plastic smaller than 5 millimeters. Although initial studies in plastic focused on pieces of this size, researchers are discovering that plastics also exist as tiny fibers. Now scientists are filtering for micron- and nanometer-sized plastic particles. A micrometer or micron is one-thousandth of a millimeter and a nanometer is one-thousandth of a micrometer. (A human hair is about 70 microns wide.) When filtering at this smaller scale, researchers are finding much more plastic in the environment than they previously thought existed.
How do microplastics affect humans and the environment?
There are three ways that plastics can impact health. First, the toxic additives used to make plastic (such as phthalates, bisphenols, and flame retardants) can leach out of plastics and into food and drinks and even our bodies. Second, when plastic is in the environment it can attract heavy metals, persistent organic pollutants, and pathogenic bacteria that attach to the surface of plastic and can harm fish, birds, or other creatures that eat the plastic. Third, microplastics < 150 micron can cross the intestinal barrier in mammals and microplastics < 20 micron can move into tissue and possibly cause inflammation and stress.
Where are they found?
Microplastics are pervasive and have been found even in the most remote part of the planet, from the top of Mt. Everest to the Mariana Trench in the deepest part of the ocean. Other studies have found microplastics in honey, beer, sea salt, tap water, and bottled water. One Canadian researcher tested tea bags and found that premium pyramid shaped mesh bags shed about 11 billion particles when brewing one cup of tea using hot water.
What are the main sources of microplastics in the environment?
In Mary’s research, she examined the effects from using plastic containers and found that fine particles can flake off the items such as ice cube trays, salt grinders, and even plastic bottle caps as they’re opened and closed.
One of the greatest sources of microplastics are fibers that are released from synthetic clothing when washed and worn. One study found that 400 plastic particles are released per gram of sweater during a 20-minute walk.
What are the trends and where does it go?
In 2015 alone, we produced 350 million tons of plastic. This number has been increasing by 4% each year ever since. Plastic used to make synthetic clothing is increasing 6% a year. Plastic packaging makes up almost 40% of all plastic produced each year. This single-use packaging is typically used for a short period of time—sometimes only a few minutes. The U.S. recycles less than 10% of the plastic it produces each year, leaving the rest of it to end up in landfills. Globally, 6.3 billion tons of plastic waste was created in 2015 and that number is expected to grow to 12 billion by 2050 if current trends continue.
What can we do?
According to Mary, there are several actions we can take to mitigate this concerning trend:
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Reduce our single-use plastic purchases (refill water bottles, buy in bulk, and buy items packaged in other materials like glass or paper)
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Push for the development of a standard method to analyze microplastics. There is currently no standard method to determine the amount of microplastic in water or tissue, which means that results from one laboratory cannot be compared with results from another lab.
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Increase the percentage of plastic that is recycled. Some countries recycle 50 percent of their packaging plastic—we can do much better than 10% here in the U.S.
Bottom line
Microplastics are everywhere. They are bad for the planet and all of its inhabitants. As a society, we need to work collectively to reduce our plastic consumption and push for changes and regulations to keep it out of our oceans and our bodies.
Learn more
The recording of Mary’s excellent presentation is available here and the slides are here. Also, Mary’s opinion piece, “Post-pandemic, plastic is the crisis we must face,” published in the StarTribune on February 14, 2021 is available here.