A new study by Dartmouth researchers concludes that seafood could be a “potentially underestimated source of PFAS exposure,” and calls for new federal guidelines for safe seafood consumption.

“Our recommendation isn’t to not eat seafood — seafood is a great source of lean protein and omega fatty acids,” Megan Romano, a co-author of the study and associate professor of epidemiology at Dartmouth’s Geisel School of Medicine, said in a statement.

“But it is also a potentially underestimated  source of PFAS exposure in humans. Understanding the risk-benefit trade-off for seafood consumption is important for people making decisions about diet, especially for vulnerable populations such as pregnant people and children.”

Ms. Romano said that prior to the Dartmouth study, “most existing research focuse[d] on PFAS levels in freshwater species, which are not what people primarily eat.”

Researchers said in the statement that their conclusions illustrate the need for “more stringent public health guidelines that establish the amount of seafood people can safely consume to limit their exposure.

“This need is especially urgent for coastal regions such as New England where a legacy of industry and PFAS pollution bumps up against a cultural predilection for fish.”

The class of man-made toxins known as perfluoroalkyl and polyfluoroalkyl substances — collectively PFAS — have been present in thousands of consumer products for decades. They are known as forever chemicals because some of them can take hundreds of years to break down. High levels of PFAS have been linked to cancer, heart disease, thyroid disease and other maladies. A federal study last year found PFAS in nearly half the nation’s tap water.

The Dartmouth study surveyed 1829 New Hampshire residents to figure out consumption frequency, portion sizes and types and sources of seafood among adults and children. At a seafood market in Portsmouth, New Hampshire, researchers purchased the most commonly consumed seafood, including shrimp, lobster, haddock, cod, salmon and tuna — to test for 26 different PFAS compounds. They said the seafood tested was “primarily sourced directly from the Gulf of Maine” and sold fresh the day it was caught.

“Among all species sampled, the highest PFAS concentrations were observed in shrimp and lobster, [with] maximum concentration [of] 2.7 ng PFOS/g in shrimp and 5.4 ng PFTrDA/g, 3.4 ng PFTeDA/g and 2.5 ng PFUnDA/g in lobster,” the study said, referring to the levels of individual toxins within the PFAS family. “Concentrations in samples of scallops, cod, haddock, salmon and tuna ranged from less than the method detection limit to <1.0 ng/g.” Ng/g is shorthand for nanograms per gram.

It remains unclear exactly how dangerous those levels are for seafood consumers.

Ms. Romano said in an email exchange last week that uniform nationwide safety levels for PFAS in seafood don’t yet exist.

She said federal and state public health institutes have yet to “generate more comprehensive guidance to identify safe levels of PFAS, if any, in food, because right now it is difficult for even highly informed consumers to make safer seafood choices.

“One of the challenges to this work is that there generally is not specific guidance to indicate what concentrations of PFAS are safe or acceptable in food,” she wrote, “but rather the available guidance (which is sparse) is based on the amount of PFAS that someone can be exposed to each day (from any source) without detectable risks to health.

“These values are only available for a limited number of PFAS at present. In our study, we used the available health guidance values from federal or state public health agencies for PFAS to help us estimate the risk of exposure to PFOS, PFNA, or PFUnDA in seafood, relative to existing health guidance values among people consuming average or high amounts of seafood.” (A co-author of the study further explains the researchers’ methodology in this video.)

“Adverse health effects related to PFAS exposure” are not expected at less than 2 nanograms per milliliter, according to the National Institutes of Health.

“There is a potential for adverse effects, especially in sensitive populations, between 2 and 20 ng/mL,” and further risk above 20.

Bonnie Brady, executive director of the Long Island Commercial Fishing Association, read the 17-page report at the request of The Suffolk Times. In an interview last week Ms. Brady said she learned some things, but said that it’s extremely difficult for U.S. consumers to trace the source of most popular seafood to where it was captured — or contaminated.

She said that most of the country’s salmon is imported from Norway or Denmark, and most shrimp comes from Vietnam or the Philippines.

“Maine hasn’t had a shrimp fishery in 10 years.

“Haddock, obviously, would be a local choice … but just generically telling me ‘shrimp’ isn’t the same as telling me wild Gulf shrimp landed in North Carolina.”

She said the fact that some of the fish tested are migratory species just underscores the difficulties in accurately tracking the contaminating source in a PFAS-infected fish.

The Dartmouth research was funded by the National Institutes of Health through the National Institute of Environmental Health Sciences, as well as a grant from the National Institute of General Medical Sciences.

Earlier this month, the U.S. Environmental Protection Agency issued its first ever PFAS standards for drinking water, mandating that within five years PFAS levels for six man-made chemicals in drinking water must be reduced to near zero levels.

In 2020, New York state set a PFAS limit on drinking water of 10 parts per trillion. The new federal standards aim to reduce that to four parts per trillion. The agency has promised up to $1 billion in federal funding to help local municipalities upgrade their systems by 2029.

In response to this month’s EPA announcement, the Suffolk County Water Authority said in a social media post that it “has been preparing for this and we are well on our way to meeting all regulatory requirements within the timeframe laid out by the EPA.”

The post went on to note that about one-third of the SCWA’s roughly 600 public supply wells that pump water from the aquifer are fitted with Granular Activated Carbon filtration systems that filter out PFAS chemicals, and that the authority’s “own internal standard … is lower than state regulatory requirements.”