According to Gram Research analysis, animals living in coastal estuaries accumulate 200 times more PFAS (forever chemicals) than those in the open ocean, with concentrations dropping from 2,139 units near river mouths to just 10.5 units in distant waters. Near shore, animals absorb these chemicals directly from polluted water and sediment, but farther out at sea, the chemicals concentrate through the food chain as larger fish eat contaminated smaller fish. This means seafood from coastal areas carries higher chemical risks, particularly bottom-dwelling fish species.
Researchers studied 342 different water animals along China’s coast to understand how dangerous chemicals called PFAS (forever chemicals) accumulate in seafood. They found that animals living near river mouths had 200 times more of these chemicals than those in the open ocean. The study shows that near shore, animals get contaminated mainly from polluted water and sediment, but farther out at sea, the chemicals move up the food chain—meaning bigger fish that eat smaller fish get more contamination. This matters because millions of people eat seafood, and the highest risks are in coastal areas where pollution is worst.
Key Statistics
A 2026 research analysis of 342 aquatic species found that PFAS concentrations in estuary animals were 2,139 ng/g dry weight, compared to just 10.5 ng/g in the Northern East China Sea—a difference of more than 200 times.
According to the 2026 study of 342 marine species across China’s coast, bottom-dwelling demersal fish showed significantly higher PFAS burdens than open-water pelagic fish, reflecting their greater exposure to contaminated sediment and feeding habits.
Research examining 342 aquatic species in 2026 revealed that the mechanism of PFAS accumulation shifts from direct environmental exposure in estuaries to food-chain magnification in offshore regions, with long-chain PFAS increasing as they move up the food web.
A 2026 analysis of coastal ecosystems found that certain PFAS types (HFPO-TrA, PFMOAA, and PFOA) were most concentrated near estuaries, while other types (C9-C14PFCAs and PFOS) increased in offshore waters, indicating different persistence and transport patterns.
The Quick Take
- What they studied: How much of a dangerous chemical called PFAS (forever chemicals) builds up in different ocean animals, and why the amounts change from coastal areas to the open sea.
- Who participated: 342 different aquatic species (fish, shellfish, and other sea creatures) collected from five different ocean zones along China’s coast between 30°N and 40°N latitude.
- Key finding: Animals living near river mouths had 200 times more PFAS than those in the open ocean (2,139 units near shore versus 10.5 units far offshore). Near shore, pollution from human activity is the main problem, but in deeper waters, the chemicals concentrate in bigger fish that eat smaller fish.
- What it means for you: If you eat seafood regularly, especially from coastal areas, you may be exposed to higher levels of these chemicals. The risk is highest for people living near estuaries and bays. However, occasional seafood consumption is still part of a healthy diet—awareness and monitoring are more important than avoidance.
The Research Details
Scientists collected 342 different water animals from five zones along China’s coast: estuaries (river mouths), bays, and open ocean areas. They measured how much PFAS (a group of man-made chemicals used in non-stick coatings and water-resistant products) was in each animal’s body. They used a statistical method called Structural Equation Modeling to figure out what was causing the differences—was it direct exposure to polluted water, or was it coming through the food chain?
The researchers compared two types of fish: demersal fish (bottom-dwellers that eat from the seafloor) and pelagic fish (open-water swimmers). They also looked at different sizes of PFAS molecules to see if smaller or larger ones accumulated differently. This helped them understand the different pathways these chemicals take into animals’ bodies depending on where they live.
Understanding how these chemicals move through ocean ecosystems is crucial because PFAS don’t break down naturally—they’re called ‘forever chemicals’ because they persist for decades. By identifying whether pollution comes from direct exposure or through eating contaminated prey, scientists can better predict where the highest risks are and help protect human health through targeted monitoring and cleanup efforts.
This study is strong because it examined a large number of species (342) across a wide geographic area, which gives a comprehensive picture of how PFAS behaves in different ocean environments. The use of advanced statistical modeling (SEM) to identify causes rather than just measuring amounts makes the findings more reliable. However, the study was conducted only in Chinese waters, so results may not apply to other parts of the world with different pollution patterns or ocean conditions.
What the Results Show
The most striking finding was the dramatic decrease in PFAS levels moving from shore to open ocean. Estuary animals had 2,139 units of PFAS, while those in the Northern East China Sea had only 10.5 units—a difference of more than 200 times. This sharp drop shows how concentrated pollution is near human population centers and river outlets.
The type of PFAS also changed depending on location. Near shore, certain types (HFPO-TrA, PFMOAA, and PFOA) were more common, likely because they come directly from industrial discharge and consumer products. Farther out at sea, different types (C9-C14PFCAs and PFOS) became more dominant, suggesting these chemicals persist longer and travel farther in the ocean.
Bottom-dwelling fish had significantly higher PFAS levels than open-water fish, even in the same location. This is because bottom fish eat from contaminated sediment and have more contact with polluted water. The researchers found that near shore, animals get most of their PFAS directly from their environment (water and sediment), but in offshore areas, the main source is eating other contaminated animals.
An interesting unexpected finding was that one type of PFAS (PFMOAA) didn’t follow the normal pattern where longer-chain chemicals accumulate more than shorter ones. This suggests different PFAS chemicals behave differently in the body and environment. Additionally, short-chain PFAS actually decreased as they moved up the food chain (from small invertebrates to fish), while long-chain PFAS increased—showing that different sizes of these molecules have opposite behaviors in ocean food webs.
Previous research has shown that PFAS accumulates in animals, but this is the first large-scale study to show how the mechanism changes from coastal to offshore areas. Earlier studies focused on single locations or specific species, but this research reveals a geographic pattern: the source of contamination shifts from direct environmental exposure near shore to food-chain accumulation in deeper waters. This finding helps explain why some coastal communities have higher health risks despite living far from industrial sources.
The study was conducted only in Chinese coastal waters, so the findings may not apply to other regions with different pollution sources, ocean currents, or ecosystems. The researchers didn’t measure PFAS in the water itself at each location, which would have strengthened their conclusions about exposure pathways. Additionally, they didn’t track how PFAS levels change over time, so we don’t know if contamination is increasing, decreasing, or staying stable. The study also didn’t examine human health outcomes directly—it only measured chemical levels in animals.
The Bottom Line
Strong evidence supports increased monitoring of PFAS in seafood, especially in coastal and estuary regions. Moderate evidence suggests that people living near estuaries should limit consumption of bottom-dwelling fish species. Weak evidence suggests avoiding seafood entirely—the health benefits of seafood generally outweigh the risks for most people, but awareness is important. Pregnant women and young children should be more cautious about high-risk seafood sources.
This research is most relevant for people living in or eating seafood from coastal areas, especially estuaries and bays. Pregnant women, nursing mothers, and young children should pay particular attention because PFAS can affect development. Commercial fisheries and seafood producers should use this information to test products and inform consumers. Environmental regulators should prioritize monitoring and cleanup in estuary areas where contamination is highest. People in inland areas eating imported seafood have lower but non-zero risk.
PFAS accumulates slowly in the body over months and years, so health effects typically appear after long-term exposure. If someone reduces their consumption of high-risk seafood, PFAS levels in their body may decrease gradually over 6-12 months, though some PFAS can remain for years. Regulatory changes and cleanup efforts in estuary areas could take 5-10 years to show measurable improvements in seafood safety.
Frequently Asked Questions
Is it safe to eat fish from coastal areas given PFAS contamination?
Occasional consumption of coastal seafood is generally safe for most people, as the health benefits of fish typically outweigh chemical risks. However, pregnant women, nursing mothers, and young children should limit consumption of bottom-dwelling fish from estuaries and bays, where contamination is 200 times higher than in open ocean areas.
What types of fish have the most PFAS contamination?
Bottom-dwelling fish (demersal species) that eat from the seafloor have significantly higher PFAS levels than open-water fish. Fish from estuaries and coastal bays have much higher contamination than those from the open ocean. Larger predatory fish accumulate more long-chain PFAS through the food chain.
How do forever chemicals get into seafood?
Near shore, PFAS enters seafood directly from polluted water and contaminated sediment. In offshore areas, the main route is through the food chain—smaller fish and organisms absorb the chemicals, then larger fish eat them and accumulate even higher levels. Industrial discharge and consumer products near rivers are primary sources.
Can PFAS be removed from the body?
PFAS breaks down very slowly in the human body and can remain for years. Reducing exposure by choosing lower-contamination seafood sources is more effective than trying to remove it after exposure. Some PFAS may gradually decrease if exposure stops, but complete elimination takes a long time.
Should I avoid eating seafood because of PFAS?
No—seafood provides important nutrients like omega-3 fatty acids and protein. Instead, vary your seafood sources, choose open-ocean fish over coastal bottom-dwellers when possible, and be especially cautious if you’re pregnant, nursing, or feeding young children. Awareness and smart choices are better than avoidance.
Want to Apply This Research?
- Track weekly seafood consumption by type (bottom fish vs. open-water fish) and source location (estuary/bay vs. open ocean). Log specific species when possible, as different fish have different contamination levels. This helps users identify their personal exposure patterns.
- Users can reduce exposure by choosing open-ocean fish species over bottom-dwelling species, varying their seafood sources geographically, and limiting consumption of high-risk species from coastal areas. The app could provide a ‘PFAS risk score’ for different seafood choices based on this research.
- Set monthly reminders to review seafood consumption patterns. Track any symptoms or health concerns that might be related to chemical exposure. For users in high-risk areas, quarterly check-ins with healthcare providers about PFAS exposure could be valuable. The app could integrate with local seafood safety alerts when available.
This research describes chemical contamination in marine animals and potential health implications, but it does not constitute medical advice. Individual health risks from PFAS exposure depend on consumption patterns, location, age, and health status. Pregnant women, nursing mothers, and young children should consult healthcare providers about seafood consumption. This study was conducted in Chinese waters and may not apply to other regions. Always consult qualified healthcare professionals before making significant dietary changes based on chemical exposure concerns. For specific health concerns related to PFAS exposure, contact your doctor or local health department.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.