High Seafood Diet May Increase Exposure to ‘Forever Chemicals’

People who eat lots of seafood may have a higher exposure to toxic chemicals known as perfluoroalkyl and polyfluoroalkyl substances (PFAS), which have been linked to health problems like cancer and birth defects, a new study suggests.

PFAS are man-made chemicals that are found in a wide variety of consumer and industrial products, including food wrappers, clothing, nonstick cookware, and fire-fighting foam. PFAS are called “forever chemicals” because they never fully break down in the environment.

They’re also abundant in our communities and our bodies. The Agency for Toxic Substances and Disease Registry estimates that more than 98 percent of Americans have some level of PFAS in their blood. Most people are exposed through contaminated drinking water.

For the new study, scientists tested PFAS levels in fresh samples of some of the most commonly consumed types of marine fish and shellfish in New England: cod, haddock, lobster, salmon, shrimp, and tuna.

PFAS in Lobster and Shrimp

Shrimp had the second-highest PFAS levels, with average concentrations as high as 1.74 nanograms per gram of flesh, the study found. In other fish and seafood, PFAS levels are typically less than one nanogram per gram, according to the study.

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

“But it also is a potentially underestimated source of PFAS exposure in humans,” Dr. Romano said. “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.”

While the study didn’t examine exactly why such high levels of PFAS were found in seafood, it’s likely that industrial contamination of the waterways over time led to elevated levels of these chemicals, says Sheela Sathyanarayana MD, MPH, a pediatrics professor and adjunct professor of environmental and occupational health sciences at the University of Washington in Seattle.

“The fish, especially bottom feeders, ingest the chemicals and then have detectable concentrations,” says Dr. Sathyanarayana, who wasn’t involved in the new study. Lobster and shrimp are both bottom feeders.

Health Risks of PFAS in Fish

People get exposed by eating these fish and shellfish that have elevated PFAS levels. Risks for people from exposure to high levels of PFAS can include elevated cholesterol, impaired liver function, an increased risk of certain cancers, reproductive problems, and birth defects, Sathyanarayana says.

Because there’s no way to remove PFAS from the body, the best way to reduce these risks is to limit exposure, says Luz Claudio, PhD, a professor of environmental medicine and public health at the Icahn Mount Sinai School of Medicine in New York City who wasn’t involved in the new study.

“I am reluctant to tell people to eat less seafood, because [seafood] can be more beneficial than other sources of protein,” Dr. Claudio says.

But people concerned about their exposure — including pregnant women who may have higher risk — can use the study findings to guide which types of seafood they choose to consume, Claudio suggests.

“Concentrations of PFAS were highest in shrimp and lobster,” Claudio says. “So, people concerned about their exposure to PFAS may want to eat less of these types of seafood.”