Perfluoroalkyl and polyfluoroalkyl substances (PFAS), also known as “forever chemicals,” have become persistent pollutants in the air, water, and soil. These chemicals are stable and can be transported throughout the water cycle, making their way into drinking water sources and precipitation. Studies have shown that consuming PFAS has been linked to negative health outcomes, leading the U.S. Environmental Protection Agency (EPA) to designate two PFAS chemicals, PFOS and PFOA, as hazardous substances in April 2024, placing limits on their concentrations in drinking water. The Great Lakes, a major freshwater source for the U.S. and Canada, are affected by PFAS contamination, with previous studies showing the presence of these chemicals.
A recent study conducted by Marta Venier at Indiana University and colleagues from the U.S. and Canada aimed to understand the sources and fate of PFAS in the Great Lakes. Between 2021 and 2022, the researchers collected 207 precipitation samples, 60 air samples, and 87 water samples from five sites surrounding the Great Lakes, including Chicago, Cleveland, Sturgeon Point, N.Y., Eagle Harbor, Mich., and Sleeping Bear Dunes, Mich. The samples were analyzed for 41 types of PFAS, revealing that PFAS concentrations remained consistent across precipitation samples, regardless of population density. Cleveland had the highest median concentration of PFAS in air samples, while Sleeping Bear Dunes had the lowest, indicating a link between population density and airborne PFAS.
In the lake water samples, the highest concentrations of PFAS were found in Lake Ontario, followed by Lake Michigan, Lake Erie, Lake Huron, and Lake Superior. The study noted a decrease in the concentration of PFOS and PFOA compared to data from previous studies dating back to 2005, but the levels of a replacement PFAS known as PFBA remained high, suggesting the need for further regulation efforts. The researchers found that airborne deposition from precipitation is the primary pathway for PFAS to enter the lakes, while sedimentation plays a role in removing the chemicals by attaching to particles as they settle to the lakebed or flow through connecting channels.
Overall, the study’s calculations indicated that the northernmost Great Lakes, including Superior, Michigan, and Huron, are accumulating PFAS, while Lake Ontario is eliminating the compounds, and Lake Erie is maintaining steady levels. The findings suggest that further actions and policies may be needed to address PFAS contamination in the Great Lakes. The researchers hope that their work will inform future efforts to mitigate the presence of these harmful chemicals in the region. The study was funded by the Great Lakes Restoration Initiative from the U.S. EPA’s Great Lakes National Program Office, highlighting the importance of addressing PFAS contamination in this critical freshwater ecosystem.
