Seafood is an underestimated source of PFAS exposure in humans

A new study led by Dartmouth College has revealed that frequent seafood eaters may be at increased risk for exposure to per- and polyfluoroalkyl substances (PFAS), a group of persistent, synthetic chemicals often referred to as “forever chemicals.”

As a consequence, the experts emphasize the need for stricter public health policies to define safe levels of seafood consumption to minimize exposure to PFAS. 

This is particularly critical in coastal regions like New England, where longstanding industrial activity and PFAS contamination intersect with a strong cultural affinity for seafood.

Risk-benefit trade-off for seafood consumption 

“Our recommendation isn’t to not eat seafood – seafood is a great source of lean protein and omega fatty acids. But it also is a potentially underestimated source of PFAS exposure in humans,” said senior author Megan Romano, an associate professor of epidemiology at Dartmouth.

“Understanding this 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.”

PFAS concentrations in commonly consumed seafood

The research included an analysis of PFAS concentrations in commonly consumed seafood in New Hampshire, complemented by a statewide survey on eating habits.

Given that inhabitants from New Hampshire and the broader New England rank among the highest seafood consumers nationally, this region provided a perfect setting for studying PFAS exposure through marine diets.

“Most existing research focuses on PFAS levels in freshwater species, which are not what people primarily eat. We saw that as a knowledge gap in the literature, especially for a New England state where we know people love their seafood,” Romano said.

Origins and impacts of PFAS in seafood

The scientists also examined extensive data from New Hampshire concerning the origins and impacts of PFAS, chemicals widely used in consumer products like plastics and nonstick coatings. 

In humans, PFAS have been linked to several health issues, including cancer, fetal abnormalities, and disorders affecting the thyroid, liver, and reproductive systems.

They have permeated environments worldwide, accumulating in soil, water, and wildlife, with nearly all Americans showing detectable levels in their blood.

“PFAS are not limited to manufacturing, fire-fighting foams, or municipal waste streams—they are a decades-long global challenge,” explained co-author Jonathan Petali, a toxicologist at the New Hampshire Department of Environmental Services.

“New Hampshire was among the first states to identify PFAS in drinking water. We’re a data-rich state due to years spent investigating the impacts of PFAS and trying to mitigate exposure.”

Highest PFAS concentrations found in shrimp and lobster

The analysis measured 26 types of PFAS in several marine species – including cod, haddock, lobster, salmon, scallop, shrimp, and tuna – all purchased fresh from a market in coastal New Hampshire and sourced from various regions.

The highest PFAS concentrations were found in shrimp and lobster, with certain compounds reaching up to 1.74 and 3.30 nanograms per gram, respectively.

The widespread presence of PFAS in the environment complicates efforts to trace how these chemicals infiltrate the marine food chain.

Certain shellfish might be more susceptible to accumulating PFAS due to their feeding habits and habitat on the seafloor, coupled with their closeness to coastal PFAS sources.

In a similar vein, larger marine species could absorb PFAS by consuming smaller creatures that tend to accumulate these chemicals in their bodies.

Evaluation of PFAS consumption levels from seafood

The experts carried out a survey involving 1,829 residents from New Hampshire to assess seafood consumption levels in the state, which proved to be substantial.

The results revealed that men in New Hampshire consume slightly more than one ounce of seafood daily, while women consume slightly less than one ounce. 

These figures surpass those recorded for men and women in the Northeast by the National Health and Nutrition Examination Survey and are over 1.5 times the national average for both genders.

For children aged 2 to 11 in New Hampshire, the daily seafood intake was around 0.2 ounces, placing them at the upper limit nationally.

Approximately 95% of the adults surveyed indicated they had eaten seafood within the last year, with 94% of them having consumed fish or shellfish in the month prior to the survey. Over two-thirds of this group had eaten seafood in the week before the survey.

Seafood consumption varies by region

However, seafood consumption varies across New Hampshire. Over half of the individuals who consumed seafood the week before the survey resided along the state’s coastal areas or near the Massachusetts border.

More than 60% of residents with household incomes below $45,000 per year reported eating seafood at least weekly, in contrast to those with higher incomes, who reported less frequent consumption.

Among the seafood tested for PFAS, shrimp, haddock, and salmon were eaten by more than 70% of adults who consumed seafood at least once a month. Lobster was on the menu for just over 54% of these adults. Among children, salmon, canned tuna, shrimp, and haddock were the most commonly eaten.

Establishing consumption advisories

According to co-author Celia Chen, a biologist at Dartmouth, despite existing federal guidelines that regulate mercury and other contaminants in seafood, no such guidelines are in place for PFAS.

“Top predator species such as tuna and sharks are known to contain high concentrations of mercury, so we can use that knowledge to limit exposure. But it’s less clear for PFAS, especially if you start looking at how the different compounds behave in the environment,” she said.

Lead author Kathryn Crawford, an assistant professor of environmental studies at Middlebury College, stressed the importance of establishing consumption advisories tailored for those most vulnerable to pollution.

“Seafood consumption advisories often provide advice for those individuals that is more conservative than for the rest of the population. People who eat a balanced diet with more typical, moderate amounts of seafood should be able to enjoy the health benefits of seafood without excessive risk of PFAS exposure,” she concluded.

The study is published in the journal Exposure and Health.

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