PFAS owe their nickname, forever chemicals, to a simple chemical fact. Their defining carbon-fluorine bonds are among the strongest in organic chemistry, which makes them essentially immune to hydrolysis, photolysis, and most abiotic degradation processes. Since the mid-twentieth century, industry has exploited this stability in everything from non-stick cookware and food packaging to firefighting foams, stain-resistant textiles, and water-repellent coatings. That durability, combined with high water solubility and an amphiphilic structure, means PFAS do not stay put. Short-chain compounds in particular dissolve readily and travel through surface waters, groundwater, and river networks, dispersing far from their emission sources. They have now been found everywhere from industrialized estuaries to the Norwegian Arctic, where long-range atmospheric and oceanic transport delivers them to ecosystems with no local industry at all.

What makes PFAS biologically unusual is where they end up inside an organism. Classical persistent pollutants such as PCBs and DDT are hydrophobic and lodge in fatty tissue, so their concentrations correlate with lipid content. PFAS flip that logic. Their molecules carry both a water-hating fluorinated tail and a water-loving head, allowing them to bind strongly to proteins such as serum albumin and liver fatty acid-binding proteins. As a result, they accumulate preferentially in protein-rich tissues, the liver, blood, and kidney, even when fat content is negligible. This also means lipid-normalization techniques used for decades to interpret legacy pollutant data simply do not work for PFAS, complicating comparisons with historical contamination studies.

Among the thousands of PFAS identified, a handful dominate aquatic contamination profiles worldwide. Perfluorooctane sulfonate, or PFOS, is consistently the most abundant compound in fish and other aquatic organisms, thanks to its extreme persistence and strong protein affinity. Long-chain perfluoroalkyl carboxylic acids, including PFOA, PFNA, PFDA, and PFUnDA, show similarly strong bioaccumulation potential because they bind serum proteins tightly and are eliminated slowly. Global monitoring data assembled in the review span a remarkable range: PFOS at roughly 2.2 micrograms per kilogram in the livers of Arctic fish in Norway, moderate levels of under 2 micrograms per kilogram in a tropical estuary in Bahia, Brazil, and staggering concentrations up to 777 micrograms per kilogram in organisms from a New York estuary contaminated by firefighting foam. In the Belgian North Sea, fish liver contained PFOS levels near 107 micrograms per kilogram, well above muscle tissue, and Swiss lake fish ranged from 0.1 to nearly 110 micrograms per kilogram.

Vietnam’s own data, though far sparser, follow the same pattern at lower intensities. A nationwide survey of waters, sediments, and biota, together with regional studies from Hanoi, major river basins, and the coast, recorded total PFAS in Vietnamese fish between roughly 0.08 and 16.9 nanograms per gram, depending on species and tissue. Freshwater fish muscle in northern Vietnam carried 0.08 to 8.06 nanograms per gram, while marine fish ranged from about 0.22 to 3.62 nanograms per gram. The single highest biota value, around 16.9 nanograms per gram, was PFUnDA in fish liver from a major river basin. In Hanoi’s urban lakes, blood concentrations in fish reached 5.2 to 29 nanograms per milliliter, exceeding liver, which in turn exceeded muscle. Marine studies along the Vietnamese coast found mollusks the most contaminated group at 22.68 nanograms per gram dry weight, likely a consequence of filter-feeding behavior that concentrates contaminated particles.

Geographically, the evidence is strikingly lopsided. Published monitoring studies cluster around Hanoi and the adjacent river systems of northern Vietnam, with additional work along major river basins and the coastline. The central coast and much of southern Vietnam remain essentially blank on the research map. The review’s authors stress that this uneven coverage means the absence of data should never be mistaken for the absence of contamination; current understanding of Vietnam’s PFAS burden is shaped more by where scientists have sampled than by where chemicals actually occur. Industrialization adds urgency: textile finishing, metal plating, paper and packaging production, leather processing, electronics manufacturing, and the use of aqueous film-forming foams at airports, military sites, and petrochemical facilities are all recognized PFAS sources, and all are concentrated in industrial provinces such as Ho Chi Minh City, Binh Duong, Dong Nai, Hai Phong, and Hanoi. Vietnam’s dense river networks then shuttle contaminants from urban centers toward biologically productive coastal aquaculture zones.

The health stakes are real, though current Vietnamese exposure estimates fall below international benchmarks. PFAS biomagnify through aquatic food webs, moving from algae to invertebrates to predatory fish, birds, mammals, and ultimately people who eat seafood, a staple of the Vietnamese diet. Ecologically, PFAS exposure has been linked to disrupted reproduction, impaired immunity, oxidative stress, and altered gut microbiomes in fish. In humans, chronic dietary exposure is associated with altered lipid metabolism, endocrine disruption, liver toxicity, immune impairment, and elevated risks of certain cancers. Regulatory bodies elsewhere have responded accordingly. The European Union sets a PFOS surface-water standard of 0.65 nanograms per liter and a biota threshold of 9.1 micrograms per kilogram in fish, while the European Food Safety Authority established a tolerable weekly intake of 4.4 nanograms per kilogram of body weight for four major PFAS combined. The US EPA’s 2022 drinking water advisories set 4 nanograms per liter for PFOA and PFOS and 10 nanograms per liter for GenX, PFHxS, and PFNA.

Vietnam, by contrast, has no PFAS-specific environmental quality standards or drinking water guidelines. National monitoring programs target conventional pollutants, so PFAS data come almost entirely from independent research groups rather than systematic government surveillance. The review identifies a chicken-and-egg problem in analytical capacity: several Vietnamese institutions own liquid chromatography-tandem mass spectrometry instruments, the workhorse technology for trace-level PFAS detection, but without mandated standards or compliance-driven demand there is little incentive to expand testing infrastructure or drive down costs. Isotope-labelled standards and certified reference materials remain expensive, further limiting routine surveillance. The 2020 Law on Environmental Protection offers a general legal framework that could eventually absorb PFAS into national monitoring, but the translation from law to laboratory has not yet begun.

The review also looks beyond the water’s edge, warning that PFAS contamination almost certainly extends into agricultural soils, crops, and livestock through irrigation with contaminated surface water, land application of sewage sludge, and atmospheric deposition. Short-chain PFAS move readily from roots into edible plant tissues, while long-chain homologues bind soil but accumulate in animal products, meaning exposure pathways shift depending on chemistry and land use. Vietnamese research on these terrestrial pathways is virtually nonexistent, even as wastewater reuse expands in water-scarce regions and aquaculture becomes increasingly intertwined with crop production. The authors advocate an integrated One Health monitoring framework spanning water, sediment, soil, crops, livestock, and aquatic organisms, alongside investment in remediation research, since microbial degradation still struggles to break the carbon-fluorine bond in terminal perfluoroalkyl acids. For a nation whose seafood culture and riverine identity are inseparable, the message of this first national synthesis is clear: the forever chemicals are already here, and Vietnam’s window for systematic monitoring before problems escalate is very much open, but it will not stay that way indefinitely.

Subject of Research: PFAS contamination and bioaccumulation in Vietnam's aquatic environments

Article Title: Current understanding of per-/polyfluoroalkyl substances (PFAS) contamination in aquatic environment in Vietnam

Article References: Van Tri, D., Quan, D. N., & Luu, T. L. (2026). Current understanding of per-/polyfluoroalkyl substances (PFAS) contamination in aquatic environment in Vietnam. Case Studies in Chemical and Environmental Engineering, 14, Article 101489. https://doi.org/10.1016/j.cscee.2026.101489

Image Credits: AI Generated

DOI: 10.1016/j.cscee.2026.101489

Keywords: PFAS, forever chemicals, Vietnam, bioaccumulation, aquatic ecosystems, PFOS, PFOA, water pollution, food safety, environmental monitoring, LC-MS/MS, One Health

For decades, scientists have explored the ways in which mercury enters and affects ecosystems, tracing its transformation from inorganic forms into methylmercury, a potent neurotoxin that biomagnifies through aquatic food webs. Traditionally, methylmercury production has been largely attributed to microbial activity, especially in oxygen-deficient sediments, or to sunlight-dependent chemical reactions involving natural organic matter. The revelation that plastics—specifically polypropylene—can promote methylmercury formation without any exposure to sunlight challenges established paradigms and suggests a new abiotic pathway operating even in dark or turbid environments such as deep lakes, underground aquifers, or beneath plastic-laden sediments.

At the heart of this discovery lies the complex chemical transformation initiated by light-independent oxidation of plastics. Through a series of meticulous field and laboratory experiments conducted in freshwater systems, researchers demonstrated that the weathering of plastics releases a unique form of dissolved organic matter, termed plastic-derived dissolved organic matter (P-DOM). Unlike previously characterized natural organic molecules, P-DOM exhibits specific oxygen-containing chemical groups capable of binding mercury ions in complex molecular interactions. This complexation is a critical prerequisite for the subsequent transfer of methyl groups to inorganic mercury, effectively transforming it into methylmercury.

The chemical mechanism proposed by the team hinges on a chain reaction sequence governed by reactive oxygen species generated during the oxidation of plastic polymers under dark conditions. These reactive oxygen species act as potent oxidants that degrade the plastic matrix, liberating methyl-bearing organic fragments into the water. Once Hg(II) ions bind to these organics, intramolecular methyl transfer reactions become thermodynamically favorable, as confirmed by advanced computational simulations using density functional theory (DFT). The simulations reinforce that within the molecular environment of P-DOM-Hg(II) complexes, methyl groups can readily migrate onto the mercury ion, yielding a stable methylmercury compound.

The implications of this abiotic methylation pathway extend far beyond the mechanistic novelty. Model-based estimates demonstrate that polypropylene debris present in freshwater environments across the globe has the potential to produce methylmercury at measurable rates, ranging from 2.8 × 10⁻⁵% to 5.5 × 10⁻²% per day in China, with slightly lower but significant rates elsewhere worldwide. Though these percentages may seem minuscule, the vast quantities of plastic accumulating in rivers, lakes, and reservoirs, combined with mercury pollution from industrial and natural sources, create a fertile environment for cumulative methylmercury generation. This could exacerbate existing mercury contamination problems and increase exposure risks to fish, wildlife, and human populations reliant on freshwater resources.

This research challenges long-held assumptions that light is an indispensable driver of abiotic chemical transformations involving mercury. By illuminating the capability of plastics to mediate methylmercury formation in dark environments, it compels a reevaluation of pollution management strategies and environmental risk assessments. Traditional monitoring systems focused on microbial activity or photo-dependent chemistry may overlook significant contributions from plastics, especially in zones where sunlight penetration is minimal. Consequently, plastic pollution emerges not only as a physical and chemical contaminant but as a catalyst of toxic metal transformations with broader ecological consequences.

Methodologically, the study stood out for its integration of in situ field observations with controlled laboratory experiments, enhancing the robustness of findings and their applicability to real-world contexts. The researchers employed advanced spectroscopic analyses and chemical assays to characterize the composition and reactivity of P-DOM, supported by state-of-the-art computational modeling to decipher reaction energetics at the molecular scale. This multidisciplinary approach provided unprecedented insights into the abiotic chemistry of mercury in freshwater environments influenced by plastic pollution.

Furthermore, the research underscores the complexity of reactive oxygen species chemistry in natural waters, emphasizing that generation of these species is not confined to photochemical processes. Instead, plastic oxidation under dark conditions can also yield these reactive intermediates, driving far-reaching transformations. This revelation opens new avenues of inquiry into the abiotic reactivity of plastics submerged in various environmental compartments, from oceanic depths to groundwater systems.

Given the ubiquity of polypropylene and related polymers in consumer products and packaging, the environmental footprint of these materials is far more insidious than previously appreciated. As plastic debris fragments into micro- and nano-sized particles suspended in water, their surface area and chemical reactivity increase, potentially amplifying P-DOM release and mercury methylation. This dynamic prompts urgent calls for stricter plastic waste management and pollution mitigation, highlighting that plastics are not merely inert pollutants but active participants in chemical cycles affecting planetary health.

The findings also raise significant concerns regarding food safety and human health. Methylmercury is known to accumulate in fish tissue, posing neurotoxic risks especially to developing fetuses and young children. The realization that plastic pollution can elevate methylmercury formation—even in dark and deeper freshwater zones where fish often forage—suggests potential pathways for enhanced contaminant transfer into aquatic food webs. This represents a critical, yet underexplored, interface between plastic pollution and toxic metal exposure.

On a global scale, the study’s regional modeling provides valuable data for policymakers and environmental agencies in China and other populous regions to understand localized risk profiles. It also sets a foundation for international collaboration to quantify and monitor the contribution of plastic pollution to mercury cycling under varying climatic and hydrological conditions. Policymakers may need to integrate these emerging findings into existing frameworks addressing heavy metal contamination, water quality standards, and plastic waste regulations.

In terms of broader scientific impact, this research exemplifies the importance of investigating non-traditional pathways in environmental chemistry. It calls for a paradigm shift in considering plastics not only as debris liable to physical hazards but as chemically active materials that can influence elemental cycles under conditions previously deemed inactive. Such insights have the potential to spur further studies into the abiotic roles of plastics on other metals and contaminants, potentially expanding the scope of environmental risk assessments.

Moreover, this discovery has profound implications for environmental monitoring strategies. Single-focus assays on microbial mercury methylators or sunlight-driven photochemical reactions may underestimate the total methylmercury burden. Comprehensive monitoring programs will need to consider abiotic plastic-driven pathways, employing targeted chemical analyses capable of detecting P-DOM signatures and their interactions with inorganic mercury. This could improve prediction accuracy regarding methylmercury hotspots and temporal dynamics in freshwater systems impacted by plastic pollution.

Scientifically, this work also highlights the significance of reactive oxygen species beyond their traditional photochemically-driven origins. It complements a growing body of literature recognizing alternative generation modes of these reactive intermediates, thus broadening the landscape of environmental oxidative chemistry. This aligns with advancing discourses around the chemical reactivity of anthropogenic materials in driving novel biogeochemical processes.

Finally, this study starkly reminds us that human-made pollutants are rewriting geochemical scripts with consequences we are only beginning to grasp. The enduring legacy of plastic pollution transcends visible litter and entanglement threats, seeding invisible chemical pathways that affect elemental cycles and ecosystem health. The emergence of plastics as hotspots for abiotic mercury methylation underscores the need for holistic and interdisciplinary approaches to tackle environmental challenges imposed by modern materials in an increasingly interconnected planetary system.

Subject of Research: Mercury methylation via light-independent plastic weathering mechanisms in freshwater environments.

Article Title: Methylmercury formation in water triggered by light-independent plastic weathering.

Article References:
Huang, Y., Liu, C., Hao, Z. et al. Methylmercury formation in water triggered by light-independent plastic weathering. Nat. Geosci. (2025). https://doi.org/10.1038/s41561-025-01766-5

Image Credits: AI Generated

The Amazon River, known for its staggering biodiversity with around 2,500 fish species, serves as an ideal laboratory for analyzing the nutritional value of various fish types. The researchers examined 59 species, concluding that smaller fish varieties possess multiple advantages over their larger counterparts. Not only were these smaller species more abundant and cost-effective, but they also boasted enhanced nutritional profiles, including higher levels of essential micronutrients such as iron and zinc, which are vital for cellular metabolism and growth.

One of the prevalent issues with larger fish species is their tendency to accumulate high levels of mercury. Mercury, a toxic heavy metal, enters water systems primarily through anthropogenic activities, such as gold mining. Unfortunately, gold mining in the Amazon often involves mercury, leading to higher concentrations of this toxin in larger fish that inhabit these regions. As these larger fish consume smaller, mercury-contaminated organisms, the mercury bioaccumulates through the food chain, posing significant health risks to consumers who eat these fish, especially vulnerable populations.

The research team emphatically stated that the prevailing focus on larger fish ignores both the ecological and health ramifications associated with their consumption. The reality of favoring large fish, such as tuna, salmon, and goliath catfish, is that these species tend to have longer lifespans, which along with their predatory diets, leads to higher mercury levels in their bodies. This phenomenon exacerbates the health concerns related to fish consumption and highlights the need for public health messaging to refocus on the seafood diet’s nutritional diversity.

Interestingly, the study advocates for the adoption of smaller fish species as a viable alternative in human diets, emphasizing their faster reproductive cycles as critical to their sustainability. The ability of smaller fish to reproduce rapidly makes them less vulnerable to overfishing, rendering them a more resilient option within the aquatic food supply. This could translate into a more sustainable seafood approach, beneficial to both consumer health and the ecosystem.

With the looming crises of population growth and climate change, the research advocates that recognizing the value of smaller fish in our diets is imperative. The steady decline of larger fish populations globally poses a threat not only to marine biodiversity but also to the nutritional security of human populations that rely on fish as a primary source of protein. The findings accentuate how small fish can help sustain nutritional requirements while simultaneously supporting conservation efforts, thereby addressing biodiversity loss issues.

Heilpern, the first author of the study, posits that human food systems are major contributors to ecological degradation. Therefore, promoting a more diverse fish diet could be a step in recalibrating our impact on the environment. As humans increasingly harvest and consume food from the ocean and rivers, understanding the delicate balance between our dietary needs and ecological integrity becomes critical in forming our future food systems.

The research highlights the necessity of incorporating broader ecological awareness into public health campaigns. By adjusting dietary recommendations to include smaller, less contaminated fish, we can improve nutritional outcomes while indirectly promoting conservation through sustainable fisheries practices. Such educational initiatives could reshape consumer behavior in favor of smaller, more sustainable fish, leading to healthier eating patterns and better public health.

Recognizing the interconnectedness of human health and biodiversity emphasizes the importance of shifting consumption patterns. By training consumers to appreciate the nutritional value and ecological impacts of smaller fish, we foster a culture that celebrates sustainable practices and rethinks our relationship with food sources. This holistic perspective could lead to long-term benefits for both human health and the health of our planet.

In summary, the findings from the Cornell-led team not only challenge preconceived notions about fish consumption but also invite a reevaluation of our dietary customs. By shedding light on the intricate tapestry of ecological and nutritional considerations, the research paves the way for informed choices about our seafood that can ultimately bring about positive change for our diets and the environment.

Emphasizing the need for sustainable fishing and public health awareness around this issue can lead to a more harmonious relationship with nature and improved health outcomes. As the research indicates, smaller fish species present viable alternatives that secure both human health and environmental integrity. The integration of these insights into food systems worldwide could catalyze a much-needed transformation for global health and biodiversity.

Subject of Research: Nutrition and sustainability related to fish consumption
Article Title: Accessible, low-mercury, and nutritious fishes provide win-wins for conservation and public health
News Publication Date: 17-Jan-2025
Web References: One Earth
References: DOI 10.1016/j.oneear.2024.12.010
Image Credits: None
Keywords: Biodiversity, Mercury contamination, Nutritional physiology, Sustainable fishing, Environmental health, Overfishing, Marine biodiversity, Public health, Freshwater fishes, Ecosystem conservation, Food systems