Understanding PFAS: Forever chemicals to be added to Canada’s toxic substances list

Expert Joseph Okeme explains what PFAS are, what we need to know, and how his research team is working to protect people and the environment.

By Andrea Lawson May 21, 2025

Non-stick pans for sale, hanging on hooks in a store display.
PFAS or ‘forever chemicals’ are found in hundreds of products in daily use, including non-stick cookware. (Adobe image)

Expert Featured In This Story

Joseph Okeme
Joseph Okeme

Assistant Professor

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The federal government is taking steps to add PFAS to the list of toxic substances, a move that would empower the government to create regulations around their use.

headshot of Joseph Okeme standing against a backdrop of greenery
Joseph Okeme

“These chemicals have been in use for a very long time, probably since the 1950s. And we see them in everything from food packaging to firefighting foams,” says Joseph Okeme, assistant professor in the Department of Chemistry and Chemical Biology.

“But we are starting to learn more about their impact on health and environment.”

Okeme explains what we know about PFAS and how his research aims to protect both people and the environment.


What are PFAS and what kinds of things are they used for?

PFAS stands for per- and polyfluoroalkyl substances, and they are generally known as “forever chemicals.”

They’re used for a wide range of products because of the way that they could be designed for different functionalities.

You can find them as Teflon used in nonstick pans, rain jackets which repel water, floor coverings like carpets because they’ve got stain and heat-resistant properties. They’re also commonly used in food packaging.

These properties have allowed them to be used in many industries, including aerospace, semiconductor, medical, automotive, construction, electronics, and aviation.


What do we know about their impact on humans and the environment?

PFAS are highly persistent in their environment because they don’t degrade easily. The same properties that make them desirable, like being water repellent, are the same properties that make them problematic.

We’re finding them across environmental samples, for example in surface and ground water, across the food chain and in humans, with studies detecting PFAS compounds in various biological like human breast milk and blood.

As xenobiotics – substances foreign to living systems – they can cause various adverse health effects. That includes fertility issues, developmental issues like low birth weight and early puberty, as well as endocrine disruption and increased risk for prostate and testicular cancer.


What are some challenges associated with studying PFAS?

They are so pervasive everywhere. The U.S. Environmental Protection Agency has estimated that there are about 9,000 individual PFAS compounds, each with molecular masses or formulation depending on their application.

They are found in air, water and soil, making traditional techniques to examine them one at a time very impractical.

We lack accurate data on the physical and chemical properties of most PFAS compounds, and current tools and technologies are insufficient. This creates a significant bottleneck in research that will allow us to better understand and monitor these chemicals in the environment.

My research focuses on the connection between environmental risk factors and human and ecosystem health.

Specifically, I am working on developing accessibly tools for ecosystem and human risk assessment. We want to make it easy to generate data that policymakers can use to formulate interventions to protect the public.

In my lab, we are developing methods that would allow us to accelerate the measurements of the physical and chemical properties and abundance of PFAS in different sample types, addressing a critical gap in the literature.

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