'Forever chemicals' are coming into Great Lakes through air, rainfall, new study shows
A considerable amount of "forever chemicals" are making their way into the Great Lakes via the air and rain, a new study says.
In fact, the findings published in Environmental Science and Technology, show that its the primary way PFAS end up in Lake Superior, offering a stark reminder that even the lake that's considered the most pristine isn't safe from the toxic chemicals.
PFAS, or per- and polyfluoroalkyl substances, are a class of thousands of compounds that are widespread and long lasting in the environment. They contaminate drinking water and build up in fish and wildlife, posing many health risks to humans, including certain kinds of cancers, reproductive harm and liver and thyroid problems.
The Great Lakes are the freshwater heart of North America. The basin is home to 10% of the U.S. population and 30% of the Canadian population, and the lakes provide drinking water for more than 40 million people.
Reducing the amount of PFAS that goes into the Great Lakes is a challenge that will require looking at every source that brings them there, said Marta Venier, an environmental chemist at Indiana University who led the research.
And the study shows that will include the air, she said.
Here are five takeaways from the study.
PFAS come in different sizes, which makes travelling easier
PFAS are used in a lot of different products, like firefighting foam, non-stick cookware, food wrappers, laundry detergents, personal care products and outdoor gear. They are popular because they make products waterproof as well as stain- and grease-resistant.
The chemicals are grouped into two different size classes: short- and long-chain. And just like it sounds, short-chain PFAS are much smaller, and because of that can easily travel long distances hitchhiking on rain and air particles.
Many long-chain PFAS were phased out and replaced with short-chain ones because it was believed that there were fewer health risks, Venier said.
As it turns out, the risks were greatly underestimated, she said.
Lake Ontario's water had the most PFAS
The scientists collected air and rain samples at five sites around the basin: two urban locations, Chicago and Cleveland; one rural site at Sturgeon Point, N.Y.; and two remote sites, Eagle Harbor, Mich. and Sleeping Bear Dunes, Mich. The team also collected lake water samples throughout each of the five lakes.
Combined with existing information on other sources of PFAS, like tributaries that drain into the lakes and wastewater treatment plants, the researchers were able to figure out what lake has the highest concentration of PFAS in its water and where most of the chemicals came from.
Lake Ontario had the highest concentration of PFAS in its water followed by Lakes Michigan, Erie and Huron. According to the study, the easternmost lake likely had the highest levels because it is the most urbanized and it is the lake that all the others drain into. Lake Superior had the lowest concentration of the toxic chemicals.
Most of the PFAS found in lakes were the short-chain, more mobile kind.
PFAS levels in the rain were the same in urban and remote sites
The study showed that when it comes to rain, it didn't matter whether it was Chicago or Sleeping Bear Dunes, PFAS levels were the same across all the lakes.
This is the first time we've seen that, Venier said, usually pollutant levels are higher near urban centers, like with PCBs or pesticides.
On the other hand, PFAS levels in the air samples were higher near urban sites and lower in the remote locations.
Rain, air important pathway for Lakes Superior, Michigan, Huron
Overall, atmosphere delivery through rain and air is an significant pathway for PFAS making their way into the Upper Great Lakes, especially Lake Superior.
According to the study, almost all the PFAS that wind up in Lake Superior come from the atmosphere compared to wastewater treatment plants and tributaries that drain into the largest Great Lake. In Lake Michigan, roughly half comes from the air and rain.
The scientists also looked at the balance of PFAS going into the lakes versus being discharged out. According to the study, Lakes Superior, Michigan and Huron are accumulating PFAS faster than they are getting rid of it.
More: Water quality issues challenge what it means to 'leave no trace' in beloved Boundary Waters
A big hurdle is a lack of information
Earlier this year, the federal government set the first national drinking water limit on certain kinds of PFAS.
While the study didn't directly test drinking water, Venier said that reducing PFAS in both the environment and drinking water will mean controlling all sources and taking a broad, multi-pronged approach.
But of the biggest challenges that remains is the lack of data on where PFAS are coming from. Venier was surprised at how little information there was on the concentration of PFAS in tributaries as well as downstream of wastewater treatment plants.
"These are data gaps that we need to fill before we can have a solid picture of all the ins and outs of PFAS in the Great Lakes," she said.
More: Almost 9 out of 10 pounds of Great Lakes beach litter each year is plastic, new report finds
Caitlin Looby is a Report for America corps member who writes about the environment and the Great Lakes. Reach her at clooby@gannett.com or follow her on X (Twitter) @caitlooby.
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This article originally appeared on Milwaukee Journal Sentinel: Air, rain bring 'forever chemicals' into the Great Lakes, study says
