The global seafood trade is spreading exposure to “forever chemicals” far beyond where the pollution occurs, with fish carrying synthetic substances from contaminated waters to consumers around the world, a new study has found.

The study looked at levels of per- and polyfluoroalkyl substances (PFAS) in more than 200 marine fish species that make up almost all global commercial fish production and found that international trade shifted the exposure of these chemicals from highly contaminated regions to countries where local fish contained lower levels of pollution.

Europe, in particular, emerged as a major hub in these exposure flows, despite not having the most contaminated fish stocks.

PFAS are a large group of synthetic chemicals used in products ranging from non-stick cookware to firefighting foams. They are known for their extreme persistence in the environment and the human body, earning them the label “forever chemicals”.

“Per- and polyfluoroalkyl substances (PFAS) are a group of more than 4,700 synthetic chemical compounds,” said Dr Julián Campo, a researcher at the Food Safety and Environment Research Group of the Desertification Research Centre in Valencia.

“....PFAS are highly toxic and pose a clear potential danger to human health, as they can act as endocrine disruptors, in addition to causing liver damage, thyroid disease, obesity, and being associated with fertility problems and cancer.”

File image: Fish from parts of Asia and Oceania, including Saudi Arabia, Thailand and Australia’s eastern coast, showed the highest PFAS concentrations relative to the global average (Marine Conservation)

Researchers combined global fisheries data, marine food-web models, and PFAS measurements from more than 3,000 seawater sampling sites to predict concentrations in 212 edible marine fish species. They then validated those predictions using real-world measurements from 150 fish samples collected across 14 countries.

Fish from parts of Asia and Oceania, including Saudi Arabia, Thailand, and Australia’s eastern coast, showed the highest PFAS concentrations relative to the global average, while fish from Africa and North America had the lowest. Species higher up the food chain consistently contained more PFAS. Freshwater fish were found to contain far higher levels than commercial marine fish.

Despite this, the analysis showed that consumption patterns and trade matter as much as where fish are caught. European countries import large volumes of fish from across the region, reshaping exposure pathways and increasing PFAS intake in places with relatively lower local contamination.

“The authors conclude that such exposure is generally low and has, overall, decreased with the gradual phase-out of PFAS production, but they also warn that the international seafood market is responsible for redistributing these exposure risks worldwide,” Dr Campo said.

File image: The analysis showed that consumption patterns and trade matter as much as where fish are caught. (PA)

From a public-health perspective, the findings suggest that wealthier regions face higher dietary exposure because of higher fish consumption and trade intensity.

“The study is of high scientific quality and stands out for its ambition and methodological robustness,” said Dr Pablo Gago, senior scientist at Spain’s Institute of Environmental Assessment and Water Research. “It integrates global data on PFAS contamination in the marine environment, bioaccumulation models in food webs, fish consumption, and international trade, covering more than 99 per cent of global marine fish production.”

He added that the work shows “human exposure to PFAS depends not only on local environmental contamination, but also on the dynamics of global food trade”.

There was, however, evidence that regulation works. The study found that global exposure risk from two widely used PFAS compounds – PFOS and PFOA – has fallen sharply since they were restricted under the Stockholm Convention in 2009 and 2019.

“The results are consistent with previous evidence identifying fish as a relevant source of dietary PFAS exposure, but they add a key element: the international redistribution of risk,” Dr Gago said. “They show that restrictions applied to PFOS have been effective, but also that unregulated long-chain PFAS continue to represent a high risk, especially through food trade.”

The authors caution that the study focuses on marine fish and does not include other dietary or environmental sources of PFAS, meaning total human exposure is likely underestimated. Still, they argue the findings underline the need for stronger coordination on food safety standards and chemical regulation in a globalised food system.