Researchers from several Ontario universities have released a new study mapping the alarming spread of microplastics across the Great Lakes, raising red flags about long-term environmental and health implications. The study, funded by the Canada First Research Excellence Fund, is the most comprehensive analysis to date of microplastic contamination in Canadian freshwater systems.
Samples were collected from over 75 locations along Lake Ontario, Lake Erie, and Lake Huron, including urban and rural shoreline zones. Results show microplastic concentrations reaching up to 250,000 particles per square kilometer in some areas—levels comparable to those found in heavily polluted marine zones.
Microplastics are tiny plastic fragments less than five millimeters in size, often resulting from the breakdown of larger plastic waste. They can be ingested by fish, birds, and even enter human drinking water systems through municipal intake pipes.
The researchers identified fibers from clothing, fragments from food packaging, and microbeads from cosmetic products among the most common pollutants. Notably, wastewater treatment plants were flagged as major contributors, especially in areas surrounding Toronto and Hamilton.
Dr. Sarah Menzies, an environmental scientist at York University and lead author of the study, said the findings should prompt immediate policy review. “Microplastics are not just an ocean problem. They are in our lakes, rivers, and possibly our bodies,” she warned.
The study calls for tighter regulations on plastic manufacturing and disposal, as well as mandatory filtration upgrades at wastewater facilities. Researchers are also urging the public to reduce synthetic fiber usage and support bans on single-use plastics.
In response, Environment and Climate Change Canada has acknowledged the findings and said it will review the data as part of its upcoming freshwater protection strategy. A spokesperson noted that the federal government is committed to phasing out unnecessary plastic by 2030.
Citizen science played a key role in the research, with local volunteers collecting water samples and conducting shoreline cleanups. “It’s a community effort,” said PhD student Julian Roy. “Science is most powerful when people are part of the process.”
As concerns grow about microplastic exposure in food and water, the study is expected to spur further research into long-term health effects. In the meantime, scientists hope their work will serve as a wake-up call to protect Canada’s precious freshwater resources.