Press release

Microplastics now pervasive in Great Lakes, with 90% of water samples surpassing safe levels for aquatic wildlife: new studies

Data spanning the last ten years reveal that the Great Lakes basin is widely contaminated with microplastics, with potentially dangerous consequences for the wildlife that live within.



August 23, 2023

However, if Canada and the United States act together soon, we can develop systems to monitor and reduce the risks that these pollutants pose to the health of these critical ecosystems.

This is all according to two new studies conducted by researchers from the Rochman Lab at the University of Toronto, in collaboration with IISD Experimental Lakes Area, published in the Canadian Journal of Fisheries and Aquatic Sciences. 

Both studies reveal widespread contamination of microplastics across the Great Lakes basin—nearly 90% of the water samples collected from the Great Lakes basin surpass at least one threshold for risk—and suggest appropriate next steps for monitoring contamination and risk, as well as mitigation. 

The first study identifies a need for a coordinated monitoring strategy for microplastics, which would necessitate developing standardized methods for measuring, characterizing, and reporting microplastics in the region – a need also recently emphasized by the Auditor General of Ontario in their recently published State of the Environment in Ontario report. 

The second study identifies a need to develop an ecological risk assessment and management framework for the region, where different levels of microplastics present in the water and sediment would trigger specific management actions. 

“It’s clear that microplastics in the Great Lakes are a problem for both Canada and the United States, and that their management should reflect this,” said Eden Hataley, Ph.D. Student, Department of Physical & Environmental Sciences, University of Toronto Scarborough.

“One way forward to address the issue could be via the Great Lakes Water Quality Agreement – the longstanding commitment between the two countries that outlines binational priorities and actions to resolve transboundary environmental problems in the Great Lakes.”

In the first study, the research team sought to understand where, how much, and what type of microplastic pollution exists in the Great Lakes and what methods researchers typically use to measure it. Existing research efforts clearly show that microplastics are pervasive throughout the Great Lakes and associated rivers in water, sediments, and wildlife (including different species of fish, birds, frogs, and mussels). In general, levels of microplastics in the Great Lakes are comparable or relatively high compared to other water bodies. 

In the second study, the research team sought to understand the present risk of microplastics to species living in the Great Lakes. The research team found that reported levels of microplastics in nearly 90% of the water samples collected from the Great Lakes basin surpass at least one threshold for risk, however, all of the sediment samples collected from the Great Lakes basin remain below safe levels.  

The Rochman Lab, in the Department of Ecology and Evolutionary Biology at the University of Toronto, is a large research laboratory with a focus on pollution in aquatic ecosystems. The primary focus of Dr. Rochman and her trainees is on plastic pollution – aiming to better understand sources, fate and effects in rivers, lakes and oceans. 

IISD Experimental Lakes Area is the world’s freshwater laboratory. A series of 58 lakes and their watersheds in northwestern Ontario, Canada, IISD-ELA is the only place in the world where scientists can research on and manipulate real lakes to build a more accurate and complete picture of what human activity is doing to freshwater lakes. The findings from over 50 years of ground-breaking research have rewritten environmental policy around the world—from mitigating algal blooms to reducing how much mercury gets into our waterways—and aim to keep fresh water clean around the world for generations to come.


For more information, please contact:

Sumeep Bath, Editorial & Communications Manager, IISD Experimental Lakes Area or (204) 599 2595

About IISD

The International Institute for Sustainable Development (IISD) is an award-winning independent think tank working to accelerate solutions for a stable climate, sustainable resource management, and fair economies. Our work inspires better decisions and sparks meaningful action to help people and the planet thrive. We shine a light on what can be achieved when governments, businesses, non-profits, and communities come together. IISD’s staff of more than 250 experts come from across the globe and from many disciplines. With offices in Winnipeg, Geneva, Ottawa, and Toronto, our work affects lives in nearly 100 countries.