A big challenge to the health of the Great Lakes takes a tiny form: microplastics, pieces of plastic no larger than 5 millimeters in size, or about the size of a pencil eraser. They have been documented throughout the lakes, in oceans, and even in tap and bottled water, sea salt and other products we eat and drink.

Microplastics’ many forms include beads, fragments, pellets, film, foam and fibers. They can be created when larger plastic items break up in sun and wave action over time, or they can be intentionally manufactured, as in microbeads and pellets. In a study of microplastics on 37 National Park beaches, microfibers were found at every site and made up 97% of the microplastic debris. The highest concentration of microplastics in this national study was found at the Apostle Islands National Seashore in Wisconsin, with an average of 221 pieces of microplastic per kilogram of sand. Modeling studies have estimated that approximately 10,000 metric tons of plastics enter the Great Lakes every year.

Microplastics studies in the five Great Lakes have shown that larger amounts are found close to urban and nearshore areas, particularly near locations where rivers, stormwater and wastewater discharge. Likewise, there have been greater amounts found in Lake Erie and Lake Ontario, which are smaller and have larger urban populations and thus more potential sources of microplastics.

Zooplankton, fish, mussels and birds in the Great Lakes have been found to ingest microplastics, mistaking the debris for their natural food. Microplastics can both attract and carry pollutants already in the water and release chemicals added to plastics to make them colorful, flexible or flame resistant. Lab studies have shown that microplastics may impact animals by delaying their developmental stages, causing problems with reproduction, even making it difficult for them to fight off disease. Although wildlife may ingest or be exposed to microplastics and their chemical additives, more research is needed to understand how they might be affected and especially how impacts can translate up the food chain.

Efforts to solve the complex problem are underway regionally, nationally and internationally.

The U.S. Marine Debris Act (2006) and Save our Seas Acts (2018 and 2020) prioritize the prevention, research, assessment and removal of marine debris, with specific actions to understand and address microplastics. The U.S. also passed the Microbead-Free Waters Act of 2015, which banned rinse-off cosmetics that contain intentionally added plastic microbeads.

A Great Lakes Marine Debris Action Plan was developed in 2020 through a voluntary, collaborative effort of 39 organizations from the United States and Canada to address marine debris through coordinated actions. This five-year action plan lays out 47 actions focused on research and monitoring, policy and management, prevention and removal of marine debris.

More recently, in March 2022, the United Nations Environment Assembly unanimously agreed to formal negotiations on a legally binding treaty to end plastic pollution, with the goal to conclude negotiations by the end of 2024. In 2022, Canada also prohibited the manufacture, import, sale and eventually export of many types of single-use plastic items.

At the local level, businesses are becoming more aware of the issue. In places like Chicago and Put-in-Bay, Ohio, restaurants are voluntarily phasing out straws and reducing single-use plastics to prevent waste before it becomes marine debris.

Solutions also begin with our personal choices. Single use and disposable items are deeply ingrained in our everyday lives, and they can all become marine debris and microplastics. By working as a community, we can all help protect the Great Lakes. We can pick up the trash we find on our local streets, in our rivers and streams, and on our beaches. We can reduce the amount of plastics we purchase and carry reusable alternatives wherever we go. Together, we can be part of the solution and prevent microplastics in the Great Lakes.

For more information on microplastics and marine debris, visit the National Oceanic and Atmospheric Administration’s Marine Debris Program website.