Study of forever chemicals in Cape Fear River fish produces some puzzling results
What a fish eats and where it sits in the food chain likely determines how “forever chemicals” build up inside it, a Department of Environmental Quality toxicologist told a state science board this week.
DEQ tested muscle tissue from 250 fish caught last summer in the Cape Fear River between Chemours’ Fayetteville Works facility and the Atlantic Ocean, Frannie Nilsen said in a presentation to the Secretaries’ Science Advisory Board.
Those fish came from 14 species, including three species of catfish, largemouth bass, striped bass and American shad. They were selected, Nilsen said, because N.C. Wildlife Resources Commission studies showed they are frequently caught in the Cape Fear River and eaten.
People subsistence fishing on the Cape Fear River were more likely to have low incomes or be food insecure, according to a June 2022 report from researchers at Duke University and Oakland University.
Chemours and its predecessor, DuPont, discharged various per- and polyfluoroalykl substances — also known as forever chemicals because of their long-lasting nature — into the Cape Fear River for decades from a facility near the border of Bladen and Cumberland counties.
DEQ wanted to understand how those chemicals build up in fish over time, information that could support both environmental regulators’ efforts to develop standards and fish consumption advisories from the N.C. Department of Health and Human Services. Right now, there is no fish consumption advisory for PFAS in the Cape Fear.
PFOS, a longtime stain repellent, was the most common chemical found in the fish fillets. Nilsen said that was expected based on previous studies looking at how forever chemicals build up in fish.
In species where chemicals were found in multiple fish, Nilsen also investigated whether higher concentrations were found in bigger fish. Nilsen expected to find that larger — and thus older — fish would have more forever chemicals in their tissue.
To her surprise, Nilsen did not find such a relationship in most of the fish species, something she couldn’t explain.
“The more that I look at this data, the more that I am confused about it,” Nilsen said. She
Next, Nilsen is planning to analyze the livers from last summer’s fish, with the expectation that PFAS will be found at higher levels there than in the fillets. The expected higher concentrations of chemicals linked with the Chemours facility would help scientists develop a better understanding of how they build up in certain species.
Nilsen paid particular attention to five forever chemicals Chemours is required to study under a 2019 consent agreement.
PFO5DA, one of those chemicals, was found in four redear sunfish taken from the Cape Fear River. The concentrations of that chemical were among the highest in the entire study.
That was in contrast with PFMOAA, another chemical Chemours will study. That chemical was only found in one fish — a largemouth bass — at very low levels.
It is surprising, Nilsen said, that the chemicals would accumulate differently because of similarities between them, as well as the fact that they were both designed to not build up in tissue.
Almost four years after the consent agreement was signed, the studies Chemours is required to conduct have barely started.
Nilsen told the science board that DEQ previously approved protocols for algae and fish toxicity studies and conditionally approved protocols for two studies on water fleas and one on worms that live in river sediment. It has reviewed the company’s plans for toxicity studies of mice and rats, but has not yet received required revisions.
Commercial chemical standards do not exist for PEPA, PFO2HxA or PMPA, Nilsen said. Those are three of the five chemicals Chemours is required to study.
In those cases, Nilsen said, “The only avenue we have for getting this toxicity data is from Chemours.”
This story was produced with financial support from 1Earth Fund, in partnership with Journalism Funding Partners, as part of an independent journalism fellowship program. The N&O maintains full editorial control of the work.
This story was originally published February 10, 2023 at 7:00 AM.