By David Nesseth
Much of what pollutes Canada can’t be seen, which is exactly what scientists like Mark Hewitt are trying to uncover. From his laboratory in Burlington, Ontario, Hewitt studies the complex mixtures of chemicals that flow through the environment, tracing how they affect fish, plants, and other organisms.
His latest focus is the Integrated Chemical Mixtures Project (ICMP), a four-year national research effort led by Environment and Climate Change Canada, to understand how everyday contaminants interact and how their combined effects might be greater than the sum of their parts, threatening ecosystems and communities.
“The iceberg is a great metaphor for this project,” says Hewitt, a senior research scientist in the department’s Aquatic Contaminants Research Division. “Because there are the known substances, which are the tip, or the visible part of the iceberg. And then you know there’s the part that’s invisible. It’s under the water. And it turns out what’s not really known is much bigger than what we do know.”
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The ICMP brings together 35 laboratories and a large team of chemists, biologists, and environmental scientists across Canada.
Using advanced tools, such as high-resolution mass spectrometry, they have planned 22 field explorations to identify what’s really in the air, soil, and water, how these interact with people and wildlife, and which of those compounds pose the greatest risks.
“It’s a huge team,” says Marie-Claude Sauvé, manager of the department’s Chemical Management Plan Research and Monitoring Section and the project’s lead coordinator. “We have experts across many disciplines, such as chemistry, biology, water and wildlife, all working toward a shared goal of understanding how mixtures behave in the real world.”
While Canada’s Domestic Substances List already includes nearly 30,000 registered chemicals and polymers manufactured in, or imported into Canada on a commercial scale, the ICMP goes further, beyond the PFAS, pesticides, and insecticides expected to be present. “We might be looking at products that are flying under the radar and compounds no one’s ever looked at before,” Hewitt explains.
A major hub for the fieldwork is Brantford, Ontario, where researchers are studying how contaminants move through the Grand River and surrounding ecosystems. Brantford offers a convenient location close to Hewitt’s Burlington lab, but it also represents a typical mid-sized Canadian city, one that faces a blend of agricultural, industrial, and urban pressures.
“Anything we learn from agricultural or urban runoff mixtures will be broadly applicable across Canada,” says Hewitt. “We’re defining mixtures as combinations of two or more known or unknown chemicals that we find across all environmental media.”
Teams in Brantford are sampling water, soil, and air around the Grand River, a nearby landfill, and the city’s wastewater treatment plant. They’re also collaborating with local Indigenous communities, industry partners, and municipal officials to connect the science to real-world solutions.
“We want to advance risk management options that make a difference where we work,” says Sauvé. “It’s all guided by the research data and what we will be finding, but also from finding out what our local partners want from us.”
Among the first priorities for the Brantford research teams are per- and polyfluoroalkyl substances (PFAS). This is a family of long-lasting synthetic compounds at the heart of dozens of major lawsuits, popularized for their water-repellent, stain-resistant, and non-stick applications, and now seen as a health risk. The scientists are investigating whether PFAS in biosolids, a byproduct of wastewater treatment, can be absorbed by plants or soil organisms such as earthworms, and how different soil types might influence that uptake.
Other ongoing studies are focused on birds that frequent the Grand River corridor. Researchers are tracking whether PFAS and similar pollutants accumulate in their tissues and whether that buildup affects their health or behaviour.
At the city’s landfill, the ICMP team is studying leachate, in order to identify chemicals and microbes that can tolerate or even break down harmful substances. It’s work that could one day lead to new, low-cost screening tools or biological cleanup methods, although any actual application potential will have to wait until the team’s work is published.
An investigation is also set to assess the health of fish along a gradient of the Grand River adjacent to the city’s wastewater facility outfall.
Air samples are planned to be collected from the landfill area and other parts of Brantford in order to detect fluorinated chemicals and “transformation products”. These are new compounds that can form as pollutants break down in the environment. Samples will undergo toxicity testing and inflammation studies on human cells to help researchers understand potential health impacts.
Fieldwork is also taking place along Ontario’s St. Clair River near Sarnia, an industrial region where the research will shed light on how complex mixtures behave in developed settings.
Ultimately, the ICMP’s findings will feed into Canada’s Chemicals Management Plan and help advance the government’s commitment to the “right to a healthy environment” under the Canadian Environmental Protection Act, 1999.
Behind the scenes, the project relies on digital collaboration through the Federal Science DataHub, a platform that allows scientists across departments to share, classify, and map research data in real time. The system converts vast datasets into visual dashboards, which streamlines analysis, improves transparency, and allows new information to be added as it’s collected.
“The Federal Science DataHub has helped to improve the Integrated Chemical Mixtures Project,” says Heather Steckley, a physical scientist with Environment and Climate Change Canada. “We’re excited about the potential for streamlining our existing processes and improving how we share and display research data.”
Sauvé says that, beyond the science, the project’s real success will depend on how its findings are applied. The results could lead to more targeted monitoring programs, upgrades at wastewater treatment plants, or new best-practice guidelines for industries and municipalities. Elements such as additional water monitoring or community education efforts could evolve from the research data, says Sauvé.
For Hewitt, the work circles back to that iceberg image, symbolizing the vast unknown beneath the surface. But with projects like ICMP, Canadian scientists may soon begin to map what lies below.
David Nesseth is a contributing editor with ES&E Magazine. Email: david@esemag.com
This article appeared in the November-December print edition of Environmental Science & Engineering Magazine.
