By: DeJenae Smith
Two months ago, if you asked me to define microplastics, I likely would have said “small pieces of plastic”, and little else. It was not until my internship with Willistown Conservation Trust and PolyGone Systems where I was introduced to the wonderfully and terribly complex world of microplastics.
So, what are microplastics? According to NOAA, microplastics are less than five millimeters in length (smaller than the size of a pencil eraser). They come in a variety of shapes and colors, and from a wide range of sources (Figure 1).
There are two subclasses of microplastics: primary and secondary. Primary microplastics are released directly into nature as microparticles (ex: fibers shedding from a t-shirt during laundry day) where secondary microplastics come from larger plastic items breaking down. Because of their size, microplastics are almost invisible to the naked eye, but are everywhere in our environment: our air, soil, and most prevalently – our waters.
While water is the world’s largest resource, we often take this for granted. Out of all countries, the United States has the highest water footprint per person, using about 2,483 cubic meters of water each year (roughly 1,800 gallons each day). And in nearly all U.S waterways, even in the cleanest Pennsylvania streams, microplastics have been discovered (Map 1).
Between October 2021 and May 2022, the PennEnvironment Research & Policy Center sampled from 50 streams in Pennsylvania that were deemed Exceptional Value, High Quality, or Class A Coldwater Trout (meaning that a stream or river is clean, cold, and has many wild trout that naturally live and breed) waters. Scientists from the Academy of Natural Sciences analyzed these water samples, finding microplastics in all 50 water bodies (Map 2, Figure 2).
More recently, a study in 2024 from Penn State University at John Heinz National Wildlife Refuge and four watersheds (Kiskiminetas River, Blacklick Creek, Raystown Lake, and Darby Creek) also found microplastics polluting the waters. Despite stark differences in the land use surrounding the studied bodies of water, the researchers were surprised to find no correlation between population density, land use, and high levels of microplastics – contradicting common thought that more people means more microplastics. Microplastics are a problem for everyone, regardless of location.
While research continues documenting microplastics in natural environments, their impacts on human health remains unclear. A recent study on mice found that microplastics can travel to the brain after being consumed, leading to symptoms similar to dementia. Though microplastics have been found in the human body, the long-term health effects are still being studied.
Despite these potentially worrying findings, there are actions we can take. Reducing plastic use is one of the most effective methods to lessen exposure – swapping to a wood cutting board and refillable glass/metal water bottles – even vacuuming your home more often can help. But, if these kinds of changes aren’t possible right now, not placing plastics in the dishwasher or microwave (even if they are labelled as safe) is just as important. High amounts of heat and radiation can cause plastic items to become unstable and shed into smaller fragments, creating secondary microplastics.
For the water both we and other living creatures use, removing litter, especially near stormwater drains, helps prevent plastic from entering waterways (Figure 3). But, it’s important to emphasize that this work should not be done alone. It is through connection with other people and organizations, and making the effort to advocate for the creation and preservation of environmentally beneficial policies that lasting changes can be made to protect our waters, air, plants, wildlife, and in turn – ourselves and one another.
Funding for this project was awarded through the “Protect Your Drinking Water” grant program, administered by the Pennsylvania Environmental Council with funding from Aqua, an Essential Utilities company.
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