For 42 years, 'forever chemicals' have been quietly climbing the Great Lakes food chain
The Great Lakes hold about 21% of the world's surface fresh water. They supply drinking water to roughly 30 million people across the US and Canada. And for at least four decades, a group of synthetic chemicals has been quietly moving through them.Researchers at the University of Notre Dame analysed
By Timesofindia.com
The Great Lakes hold about 21% of the world's surface fresh water.
They supply drinking water to roughly 30 million people across the US and Canada.
And for at least four decades, a group of synthetic chemicals has been quietly moving through them.Researchers at the University of Notre Dame analysed 42 years of biological records from the Great Lakes, mapping out how per- and polyfluoroalkyl substances, PFAS, or what most people call "forever chemicals", have moved across the region and contaminated a wide range of wildlife.
The research was published in the Journal of Environmental Quality.
The team synthesised 50 studies containing 2,500 biological measurements, documenting the spatial and temporal variation in PFAS across the largest group of freshwater lakes in the world.What PFAS actually arePFAS were invented to be indestructible.
The carbon-fluorine bond at the core of these compounds is one of the strongest in all of chemistry.
It resists heat, water, and biological degradation.
That made PFAS incredibly useful in nonstick cookware, waterproof clothing, food packaging, firefighting foam, and dozens of other industrial applications.
It also means that once they're in the environment, they don't leave.
They accumulate.
The study focused on six of the most commonly detected PFAS compounds across the Great Lakes, tracking not just where they showed up, but how they moved through the food web.How the food web carries the load"We focused on the biota, not the water or the sediment, to determine what chemicals get into the organisms from algae and microbes all the way up to the top predators, like salmon and bald eagles," said Gary Lamberti, Nieuwland Professor Emeritus of Aquatic Science at Notre Dame.When PFAS enter the water, algae absorbs them.
Aquatic insects eat the algae.
Fish eat the insects.
And at every step, the concentration of PFAS increases, a process called biomagnification.
By the time you get to a lake trout or a bald eagle at the top of the chain, the chemical load is far higher than anything found in the water itself.
PFAS concentrations in natural foams on lake shorelines, for instance, can be up to 7,000 times higher than in the surrounding water, because PFAS are surfactants that build up wherever air and water meet.But the researchers found that this process isn't as straightforward as it sounds. "There are some different pathways to get to the top of the food web, which are impacted by which groups of organisms we have," said Daniele De Almeida Miranda, assistant research professor and co-investigator on the study.
An organism that lives entirely in the water accumulates PFAS both through what it eats and directly through the water itself.
But a bird eating a fish gets an entirely different chemical load — because it doesn't exchange with the water the way aquatic creatures do.
The route matters.
And different routes produce different results.Each lake tells a different storyPeter Martin, the lead author on the paper and a former undergraduate student who started the project during his junior year in 2022, noted that there wasn't one consistent trend across all five lakes. "Each lake had its own specific temporal pattern," he said.The research showed the lowest contamination levels in Lake Superior and the highest in Lake Ontario, a pattern that aligns with population density and manufacturing activity in the surrounding regions.
Lakes Superior and Michigan are also larger and deeper, which plays a role.The average time a single drop of water spends in a lake ranges from less than three years in Lake Erie to 200 years in Lake Superior.
It means that for Lake Superior, contamination introduced decades ago is still cycling through the system today. "Unfortunately, the Great Lakes hold onto their water and contaminants for a very long time, meaning there's ample time for toxins to be taken up by the biota," Lamberti said.What this study ultimately shows is that the contamination of the Great Lakes isn't a single event with a source and an endpoint.
It's an ongoing process playing out across a timescale that makes it easy to ignore until the numbers become impossible to explain away.
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