PFAS 101

The more people understand about the chemicals and pollutants that affect our waterways, the better equipped we are to protect them. One emerging concern we’ve been hearing more about from researchers, conservation groups, and communities is PFAS — often called “forever chemicals.”

These substances are found all around us, from the clothes we wear to the packaging our food comes in. And while they make life more convenient, they’re also showing up in our rivers, lakes, and drinking water. This blog is part of our effort to share what’s known about PFAS, their impacts on people and ecosystems, and what’s being done to monitor and reduce them.

What are PFAS?

PFAS stands for per- and polyfluoroalkyl substances — a group of over 15,000 human-made chemicals used in a wide range of products. They’re commonly added to items like clothing, furniture, and household goods to make them water-, dirt-, or stain-resistant. PFAS can also be found in cosmetics, food packaging, and firefighting foam.

One of the major concerns with PFAS is their impact on human health and the environment. These chemicals contain extremely strong carbon-fluorine bonds, which make them very slow to break down. This earned them the nickname “forever chemicals”, as it can take As a result, PFAS can accumulate in people and wildlife over time. Ongoing research has linked PFAS exposure to metabolic disorders, weakened immune function, and a higher risk of certain cancers.

How do PFAS end up in water?

PFAS can accumulate in ecosystems, leading to pollution of air, soil, and water. This contamination can affect agricultural crops, livestock, and ultimately, drinking water — creating a pathway for PFAS to enter the human body.

Because PFAS are used in many everyday products, they often leach into the environment through landfills, wastewater treatment plants, and industrial waste. These substances travel through soil and water, eventually reaching freshwater sources across Canada. This includes lakes and rivers that communities rely on for drinking water and recreation.

Are there PFAS in the Great Lakes?

Although there is no globally agreed-upon “safe” level of PFAS, Canada has set a drinking water guideline of less than 30 nanograms per litre (ng/L) for 25 common PFAS. Some areas, like the Great Lakes and the St. Lawrence River, are showing elevated PFAS levels due to cross-border leaching from both Canadian and American sources. For example, levels in Hamilton Harbour (Lake Ontario) reached 25 ng/L in 2023 — below the guideline, but a sign of increasing accumulation.

One common misconception about the Great Lakes is that there is a low retention time (meaning water enters and exits each lake quickly). In actuality, most of the water will spend several years in each lake, ranging from two years in Lake Erie to nearly 200 years in Lake Superior! This means PFAS entering the lakes now could still be present decades from now, making the Great Lakes particularly vulnerable to accumulation of PFAS.

What is happening with PFAS?

As PFAS pollution continues to grow, researchers are working to better understand its health and environmental impacts. They’re also developing new ways to remove PFAS from ecosystems.

Currently, detecting PFAS requires expensive, lab-based testing. Creating more affordable, rapid testing methods would allow municipalities and agencies to monitor PFAS more frequently and accurately assess the scale of contamination.

In the meantime, individuals living in high-risk areas can reduce their exposure by using water filtration systems certified to remove PFAS. Options include activated carbon filters, reverse osmosis, and ion exchange systems — but they must meet NSF International certification standards to be effective.

Why we’re paying attention

PFAS are just one of the emerging contaminants that threaten freshwater ecosystems in Canada. As part of our Lake Erie Rangers program, Water Rangers is raising awareness to ways to make monitoring more accessible, including piloting new tools and supporting citizen science efforts to track pollutants like PFAS.

We’ll continue sharing updates as this field evolves — because understanding the problem is the first step in solving it. Together, we can work towards healthier lakes and rivers for generations to come.