Scientists are tracking rising levels of “forever chemicals” in the Great Lakes and St. Lawrence River, where contamination threatens drinking water for tens of millions of people in Canada and the United States.
Jaela Bernstien reports for CBC News.
In short:
- Health Canada cut the recommended drinking water limit for PFAS to 30 nanograms per liter, far lower than previous allowances, spurring calls for tighter oversight.
- PFAS levels are highest in Lake Ontario, where industrial and municipal discharges have contributed to concentrations approaching two-thirds of current limits.
- Conventional water treatment rarely removes PFAS, and researchers warn that even as older forms decline, newer short-chain compounds may persist or rise.
Key quote:
“There’s definitely a chemical signature of PFAS in the Great Lakes and the St. Lawrence, which we attribute to just the sheer number of cities and people, and the wastewaters and industries that are all being released.”
— Sébastien Sauvé, Université de Montréal environmental chemistry professor
Why this matters:
PFAS pollution in the Great Lakes highlights a growing public health dilemma. The watershed supplies drinking water to roughly 48 million residents across two nations, meaning even low-level contamination has far-reaching consequences. Studies link certain PFAS compounds to cancer, fertility problems, hormonal disruptions and developmental delays in children. Unlike past contaminants such as PCBs, PFAS are more persistent and more widespread, creating a cycle where new versions replace those phased out. Their mobility through air and water ensures pollution crosses borders, leaving communities downstream with few defenses.
Related: 'Forever chemicals' are found in the Great Lakes through air and rain
