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Researchers detect 'forever chemicals' in a third of the Iowa streams they tested

Water runs off a central Illinois farm into the East Branch Embarras River through a tile drainage pipe.

Researchers have detected the substances known as forever chemicals in a third of the Iowa streams they tested. The scientists say it’s significant that they found the toxic PFAS chemicals in remote and rural areas, away from sites typically known to have used them.

It’s well established that sites like airports and military bases are common sources of PFAS contamination across the country. Researchers at the U.S. Geological Survey and the University of Iowa say a significant finding in their recent survey is that they detected PFAS in agricultural streams that weren’t associated with those sites.

“I think it indicates that there are likely sources that we’re not probably thinking about correctly. That there are ways these things can reach parts of the environment that don’t necessarily…aren’t tied to the ones you read about in the news like an airport or a military base,” said David Cwiertny, who directs the Center for Health Effects of Environmental Contamination at the UI.

Researchers and advocates have been sounding the alarm about PFAS for years. A class of manmade chemicals that number in the thousands, the substances were first created in the 1930s and were prized for their ability to repel oil and water and to resist heat. They’ve been widely used in industrial and consumer products around the world for decades, in everything from firefighting foam and nonstick pans to raincoats and cosmetics.

The same properties that manufacturers loved about PFAS are also what make them so concerning: they don’t break down naturally, hence the name “forever chemicals." The substances have been linked to a slate of health issues, including increased risks for immune response issues, low birth weights, kidney and testicular cancer, and high blood pressure or pre-eclampsia in pregnant women.

Still, monitoring in Iowa falls far short of the testing that’s been done in other states like Minnesota, Wisconsin and Michigan.

Researchers at the USGS and the UI wanted to set a “baseline” for PFAS levels in the state. Between June 2019 and January of 2020, they took 119 samples from 60 streams across Iowa, with 88 percent of the state’s water basins covered by that sampling network.

USGS research hydrologist Dana Kolpin says the sites were chosen largely out of convenience: they were locations where the agency was already doing other testing. And the samples were not taken during times when researchers would expect higher levels of PFAS, such as around rain events after farmers have applied biosolids to their fields (byproducts of municipal wastewater treatment that are applied as soil additives and can contain PFAS).

Because of that, Kolpin says the levels they detected are likely an underestimate, even as concerning as he says they are.

“If we're still finding it even with this kind of, ‘let's just see what's out there’, convenient sampling, then that shows that target sampling really could pick up something that maybe would start exceeding levels [considered safe],” Kolpin said. “We're really underestimating what could be out there.”

The highest levels detected were downstream from a wastewater treatment plant, which the researchers say is valuable information for state regulators who currently doing their own PFAS testing.

According to the study, the highest level of an individual PFAS chemical was 134 ng/L of PFBA in an agricultural stream. The highest cumulative level (concentrations of multiple PFAS chemicals added together) was 194 ng/L, downstream of a wastewater treatment plant.

Neither of those levels technically exceed the EPA’s lifetime health advisory for PFAS in drinking water. While the advisory is set at 70 ng/L, it only applies to PFOA and PFOS, the best known chemicals within the PFAS family. The limit is also unenforceable.

Researchers and advocates say it would be shortsighted to dismiss levels that don’t exceed the EPA’s advisory; they argue the agency has been far too slow to regulate contaminants like PFAS. Indeed, some states like Michigan and New Jersey are setting their own legally enforceable limits which are far lower than the federal government’s (this week the EPA did announce a “PFAS Strategic Roadmap” which does include timelines for setting enforceable limits for the substances).

Kolpin says that finding PFAS, even at low levels, is concerning because they bioaccumulate and don’t break down naturally.

“It may not mean something today, but if you keep ingesting it, you keep building it up, it may mean something to you five years from now, 30 years from now,” he said. “If a compound bioaccumulates, at least to me means we should be concerned enough at least to start looking at it and doing more research to see what are those consequences for such low levels.”

Cwiertny says the findings should be concerning for people who eat fish from Iowa streams, and especially for Iowans who get their drinking water from private wells, which are largely unregulated and are far more vulnerable to contamination.

“These chemicals are out there in places that are sort of beyond the obvious ones where you might look for them, by the so-called point sources,” Cwiertny said. “We probably need to devote more time to researching and studying and sampling and monitoring these chemicals in these places so we can better piece together the puzzle of ok, what else might be there? When might there be the highest concentration and the greatest risk to the ecosystem and human health?”

The researchers are already working on a follow-up study, using a more targeted approach to sample both water, stream sediment and minnows to get a better understanding of the scope of PFAS plumes and how they compound in the ecosystem.

Kate Payne was an Iowa City-based Reporter