Approximately 22 million pounds of plastic debris enter the Great Lakes annually, posing a significant threat to the health of our regional communities.
Microplastics are small particles of plastic, specifically less than five millimeters, that continue to break down but never go away. They may be small, but microplastics can have severe and often unseen consequences for humans and animals. Researchers have grouped the effects on human health into three categories: chemical, physical, and biological.
| Effects | Source | Harm |
| Chemical | Plastics that contain toxins like colorants or flame retardants can release these toxins when exposed to heat and erosion. | Toxins are stored in human and animal tissues and can disrupt the endocrine system, causing infertility, birth defects, and premature births. |
| Physical | Microfibers can be physically inhaled from the air. | Inhalation can lead to inflammation, antimicrobial resistance, and an imbalance in the gut microbiota. |
| Biological | Bacteria can grow on microplastics. | Microplastics can function as vectors for spreading disease and infection through inhalation or digestion. |
40 million people and more than 3,500 species rely on Great Lakes water. Beyond our health, microplastics can impact multiple facets of life:
| Source | Examples |
| Primary | Resin pellets– nurdles Microbeads– exfoliation creams, toothpastes, hand soap |
| Secondary | Plastic fragments– pieces of foodware, bottles, bags Microfibers– synthetic fabrics Tire particles– tire wear and tear |
Primary source microplastics are intentionally produced to be small. Common primary sources of microplastics include microfibers and resin pellets. Resin pellets, or nurdles, are raw plastic beads that get melted to create plastic products. They are a common industrial primary source, and they enter waterways from improper disposal or loading and unloading processes. Microbeads are a much smaller form of plastic pellets used in beauty products for exfoliation. Fortunately, several states have phased out the use of microbeads, which led Congress to pass the Microbead-Free Waters Act in 2015.
Secondary source microplastics are produced from larger plastics that are broken into smaller pieces by waves and erosion. Secondary microplastics include small pieces broken off of plastic cutlery, water bottles, straws, toys, or plastic bags. Secondary sources of microplastics can also be landfills, where plastics can degrade into microplastics, and wastewater treatment plants, where microplastics can be sent directly into the environment. Microfibers are a significant source of microplastic pollution because they are released from washing synthetic textiles. It is normal for clothing to shed small strands when washed, but it becomes problematic when the fabric contains plastic materials that don’t break down. Rubber tire particles, or TWPs, collect on roads, where some particles get trapped and others are transported by stormwater runoff into soils, sewers, and/or surface waters. Unlike wastewater, stormwater in the Great Lakes region is typically not treated before it enters the nearest lake or river. Reducing our use of plastics as consumers can help reduce the quantity of secondary microplastics in the Great Lakes.
Microplastics are, in a very literal sense, a small part of a much larger problem. Businesses can capitalize on consumer demand for healthy bodies and a healthy planet by offering plastic alternatives, microplastic filtration systems, and designing business plans that avoid plastics altogether. The challenges are massive, requiring more research, stricter internal business policies, and widespread changes in consumer behavior. GLBN advocates for measures to reduce reliance on single-use plastics, encourages businesses to adopt best practices to reduce plastic consumption, and supports policies that address plastic pollution systematically in the Great Lakes region.
Check out our recent microplastics webinar with an expert panel! : Microplastics Webinar
This work on microplastics is a collaborative effort with a research team from the University of Michigan School for the Environment and Sustainability. The research team is comprised of master’s students Elissa Adamson, Lily Buckley, Meredith King, and Claire Newman. The overall goal of this collaboration is to expand and deepen engagement with the GLBN through a microplastics campaign. This campaign will identify best practices for businesses to reduce their reliance on plastics and increase advocacy opportunities for plastic legislation.
Blackburn, K., & Green, D. (2022). The potential effects of microplastics on human health: What is known and what is unknown. Ambio, 51, 518–530. https://doi.org/10.1007/s13280-021-01589-9
Chen, G., Li, Y., & Wang, J. (2021). Occurrence and ecological impact of microplastics in aquaculture ecosystems. Chemosphere, 274, 129989. https://doi.org/10.1016/j.chemosphere.2021.129989
Frederick, R. (2023, February 6). Sounding the alarm on microplastic pollution. Penn State University. https://www.psu.edu/news/research/story/sounding-alarm-micro-plastic-pollution
Great Lakes Commission. (n.d.-a). About the Lakes. Retrieved June 17, 2025, from https://www.glc.org/lakes/
Harvard T.H. Chan School of Public Health. (2025, March 19). Microplastics may disproportionately harm vulnerable communities. Harvard T.H. Chan School of Public Health. https://hsph.harvard.edu/news/microplastics-may-disproportionately-harm-vulnerable-communities/
Helm, P. A. (2020). Occurrence, sources, transport, and fate of microplastics in the Great Lakes–St. Lawrence River Basin. In J. Crossman & C. Weisener (Eds.), Contaminants of the Great Lakes (Vol. 101). Springer. https://doi.org/10.1007/698_2020_557
Hoffman, M. J., & Hittinger, E. (2017). Inventory and transport of plastic debris in the Laurentian Great Lakes. Marine Pollution Bulletin, 115(1–2), 273–281. https://doi.org/10.1016/j.marpolbul.2016.11.061
NOAA. (2024, April). What are microplastics? National Ocean Service. Retrieved January 29, 2025, from https://oceanservice.noaa.gov/facts/microplastics.html
Reda, O. (2024, April). Adopt-a-Beach: 20 years of Great Lakes litter data. Alliance for the Great Lakes. https://greatlakes.org/wp-content/uploads/2024/04/AGL_AAB_VisReport_April2024_Final1.pdf
Tamis, J. E., Koelmans, A. A., Dröge, R., Kaag, N. H. B. M., Keur, M. C., Tromp, P. C., & Jongbloed, R. H. (2021). Environmental risks of car tire microplastic particles and other road runoff pollutants. Microplastics and Nanoplastics, 1, Article 10. https://doi.org/10.1186/s43591-021-00008-w
Van-Hiep Hoang, et.al., “Sources, environmental fate, and impacts of microplastic contamination in agricultural soils: A comprehensive review.” Science of The Total Environment, Volume 950, 2024, https://doi.org/10.1016/j.scitotenv.2024.175276.