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Researchers at the University of Notre Dame have developed the most comprehensive study to date of how PFAS moves through the Great Lakes food web.
The study, published this spring in the Journal of Environmental Quality, analyzed 42 years of research, combining about 2,500 samples of algae, fish, birds and other organisms in a so-called meta-analysis to identify trends.
PFAS refers to a group of man-made, long-lasting compounds that are associated with a variety of human health issues. It can enter waterways through landfills, wastewater, and industrial facilities.
“What we’re finding is that the food web itself is a vehicle for moving these chemicals from one organism to another,” says study co-author Gary Lamberti, professor of aquatic sciences at the University of Notre Dame. “So this is a more holistic view than what we knew before.”
The study found that one PFAS chemical, known as PFOS, has declined dramatically over the past two decades, following industry’s voluntary phase-out in the early 2000s.
“If we stop manufacturing these chemicals, eventually their concentrations in the food chain will decrease,” Lamberti said. “This is some good news about how we can manage these chemicals.”
These declines were seen in the lower Great Lakes region (Ontario and Erie), likely because these regions are home to heavy industry that uses chemicals.
However, little reduction in PFOS was observed in the upper reaches of Lake Superior in Michigan and Huron. This is probably because the water body is larger than the downstream lake. In contrast to Lake Erie and Lake Ontario, which are shallow, water stays in the upper lakes for about 60 to 170 years.
A map showing where samples included in the study were collected from the Great Lakes. (Image provided by: Journal of Environmental Quality)
A map showing where samples included in the study were collected from the Great Lakes. (Image provided by: Journal of Environmental Quality)
The study also confirmed that concentrations of these chemicals increase as they move up the food chain. Research shows that algae and plants have the lowest concentrations because they grow quickly and die quickly.
However, predators such as salmon and eagles had the highest concentrations because they eat large amounts of prey that is high in accumulated PFAS.
Fish contains potentially dangerous levels of these chemicals, prompting warnings across the state about how much is safe to eat. Michigan has been testing fish for PFAS since 2012.
“If we can understand what the levels of PFAS are in the food chain, we can better communicate the risks of consuming these potentially toxic food sources,” said Katherine Manz, a professor of environmental health at the University of Michigan who was not involved in the study.
What kind of fish is safe to eat?
View state and local guidelines here.
But since PFAS chemicals are found in everyday products and are very difficult to avoid, Manz said the best advice is to use less. Online databases can help consumers avoid certain chemicals.
Manz said the study also pointed to some interesting gaps in research on PFAS dynamics, such as a lack of data on specific species.
Finding PFAS data on salmon, trout and some birds was easy, Lamberti said. But information about “less attractive” small fish, invertebrates and algae was more difficult to come by.
This study focused on only six of the most commonly tested PFAS chemicals, but there are more than 15,000 chemicals out there, according to the National Institutes of Health.
Tools to analyze the range of these chemicals are still evolving, said Vernon LaRone, CEO of Wave Lumina, a Traverse City-based startup that is developing rapid test kits for PFAS in water and soil.
“It’s a chicken-and-egg situation,” said LaRone, who was not involved in the study. “We need analytical methods that are robust and reliable enough to measure these things before we can regulate them with specific limits.”
Lamberti said there are still many questions about how these chemicals change in the lake as climate change increases temperatures, changes ice formation, and industry introduces new chemicals.
“Everything we put into the Great Lakes, not just the water but the chemicals that are in it, is going to be there for a very long time, so we have to be very cognizant of how we treat the lakes and what we put into them,” Lamberti said.
