The untold story of PFAS alternatives: Insights into the occurrence, ecotoxicological impacts, and removal strategies in the aquatic environment

A novel single-chamber bio-electro-Fenton for E2-3S removal: Insights into the effects of wastewater-derived DOM composition from molecular and species levels

This study developed a novel single-chamber bio-electro-Fenton (SCBEF) system by innovating the wettability and catalyst of the air cathode, and investigated the effect of wastewater-derived dissolved organic matter (DOM) on the removal of 17β-estradiol-3-sulfate (E2-3S) by the system. Results indicated that prepared hydrophilic interface catalytic layer was more suitable for the in-situ generation of H2O2 in the SCBEF system, with the highest H2O2 and coulombic efficiencies achieved at an LA132/SP ratio of 0.6. Air cathodes loaded with developed bimetallic nitrogen co-doped carbon catalyst could efficiently catalyze H2O2 into ·OH radicals, with the ·OH radical yield significantly higher than that of cathodes loaded with a monometallic catalyst. The volumetric power density and ·OH radical yield of the SCBEF system based on the developed air cathode were significantly improved (>30 %). E2-3S was effectively removed in SCBEF system, with a removal rate of 99 %. Although the SCBEF remained effective in degrading E2-3S after the introduced wastewater-derived DOM, the degradation kinetics of E2-3S varied significantly across groups. The variations in DOM composition and bacterial community were further analyzed by ultrahigh-resolution mass spectrometry and high-throughput sequencing, and combined with electrochemical assay and network analysis to reveal the relationships explaining how DOM composition affects E2-3S degradation by regulating microbes and ·OH radicals. DOM composition reshaped degrading and electricity-producing microbes and participated in the competition for ·OH radicals, which were considered potential causes affecting the degradation of E2-3S. Relevant findings provide valuable insights for the development and optimization of the SCBEF system.

Legacy and emerging per- and polyfluoroalkyl substances in eggs of yellow-legged gulls from Southern France

More than 70 years of industrial production of per- and polyfluoroalkyl substances (PFAS) have resulted in their ubiquitous presence in the environment on a global scale, although differences in sources, transport and fate lead to variability of occurrence in the environment. Gull eggs are excellent bioindicators of environmental pollution, especially for persistent organic pollutants such as PFAS, known to bioaccumulate in organisms and to be deposited in bird eggs by maternal transfer. Using yellow-legged gull (Larus michahellis) eggs, we investigated the occurrence of more than 30 PFAS, including the most common chemicals (i.e., legacy PFAS) as well as their alternatives (i.e., emerging PFAS) in the Bay of Marseille, the second largest city in France. Compared to eggs from other colonies along the Mediterranean coast, those from Marseille had PFAS concentrations ranging from slightly higher to up to four times lower, suggesting that this area cannot be specifically identified as a hotspot for these compounds. We also found several emerging PFAS including 8:2 and 10:2 FTS, 7:3 FTCA or PFECHS in all collected eggs. Although the scarcity in toxicity thresholds for seabirds, especially during embryogenesis, does not enable any precise statement about the risks faced by this population, this study contributes to the effort in documenting legacy PFAS contamination on Mediterranean coasts while providing valuable novel inputs on PFAS of emerging concern. Identifying exposure in free-ranging species also participate to determine the main target for toxicity testing in wildlife.

Roles of oxygen vacancies in layered double hydroxides-based catalysts for wastewater remediation: fundamentals and prospects

Wastewater globally is a significant concern for environmental health and for the sustainable management of water resources. Catalysed based advanced oxidation processes (AOP), as a relatively low operation cost and high removal efficiency of pollutants method, has a promising potential to treat the wastewater. Among the numerous catalysts, Layered Double Hydroxides (LDHs) stands out for lamellar structure, high charge density, and tuneable properties. Meanwhile, oxygen vacancies engineering could modulate the electronic properties of materials and create active centres to regulate the poor charge transfer capability of LDHs. In this regard, this review is focused on how to create and confirm the oxygen vacancies, as well as the applications of the wastewater treatment from different AOPs. It starts with the synthesized of oxygen vacancies via chemical reduction method, plasma etching method, hydrothermal treatment method, ion doping strategy. Followed by the description of characterization methods, including EPR, XPS, XAS, Raman. Finally, the role of oxygen vacancies in LDHs for contaminant removal across various systems, including photocatalysis, electrocatalysis, Fenton reactions, and sulfate radical-based processes, was thoroughly examined and analyzed.

Systematic Exploration of Potential Toxicity Targets and Molecular Mechanisms of Emerging Short-Chain PFAS Substitutes: PFBA- and PFBS-Induced Hepatocellular Carcinoma Based on Toxicity Network Analysis, Machine Learning, and Biomimetic Calculations

Perfluorobutanoic acid (PFBA) and perfluorobutanesulfonic acid (PFBS) are short-chain alternatives to traditional perfluoroalkyl and polyfluoroalkyl substances (PFASs). Long-term exposure to these pollutants is closely associated with hepatocellular carcinoma (HCC). However, the toxic targets and mechanisms underlying PFBA- and PFBS-induced HCC remain unclear. To address this knowledge gap, this study employed a multifaceted approach encompassing network toxicology, molecular docking, and molecular dynamic simulation. Thirty-six core targets associated with PFBA- and PFBS-induced HCC were identified, and 12 key genes were initially screened through network toxicity analysis. Subsequently, based on the TCGA and ICGC datasets, three classical algorithms were applied to screen key genes: PPARG, ESR1, and ALB. Further exploration of the HCC-related dataset from the GEO database identified six critical genes: PPARG, ESR1, CD36, ABCA1, ACACA, and ALB. Survival analysis and ROC analysis based on the TCGA dataset revealed and validated the strong association between the expression levels of key genes (PPARG, ESR1, and ACACA). Single-gene GSEA showed that these three key genes may induce HCC through multiple biological pathways via interfering with the normal growth and development of hepatocytes and promoting inflammation and cell proliferation. Ultimately, molecular dynamics demonstrated the strong binding affinities between PFBA, PFBS, and the three protein receptors, with the best stability and flexibility of the interaction between PFBS and PPARG. These findings provide insights into the theoretical foundation for applying network toxicology, molecular docking, and molecular dynamic simulations in environmental pollutant research.

Selective Recognition and Extraction of Short-Chain Perfluoroalkyl Carboxylates by a Supramolecular Receptor

A supramolecular receptor for short-chain perfluoroalkyl carboxylates was developed. The receptor displays a cage-like geometry, with a defined binding site for the carboxylate head groups and an opening for the perfluoroalkyl side chains. The anionic guests are bound via multiple CH···O hydrogen bonds, as revealed by the crystallographic analysis of an adduct between the receptor and trifluoroacetate. The receptor can be used for the selective extraction of perfluoroalkyl carboxylates from buffered aqueous solutions containing fluoride, chloride, nitrate, carbonate, acetate, and phosphate.

Antioxidant system alterations and oxidative stress caused by polyfluoroalkyl substances (PFAS) in exposed biota: a review

Contamination of aquatic and terrestrial organisms by Perfluoroalkyl substances (PFAS), emerging contaminants, is widespread, as these compounds are present in water, soil, air, and food, owing to their environmental persistence. PFAS exposure induces biochemical process alterations associated with the disruption of the antioxidant defense system in several species. This review aims to discuss how PFAS-induced antioxidant system alterations lead to changes in biochemical processes in different organisms exposed to these pollutants. This disruption, then leads to an imbalance in antioxidant defense systems, contributing to the formation of reactive oxidative species (ROS), which, in turn, can be exacerbate oxidative stress, induce cellular damage, enhance lipid peroxidation, destabilize lysosomal membranes, and cause genotoxic effects, ultimately compromising DNA integrity. In acute tests, PFAS have led to mortality, growth inhibition, diminished behavioral and locomotor abilities, and reproductive impairment. PFAS-induced effects differ with varying species or types of substances, and further bioaccumulation through food chains exacerbates environmental contamination, carrying considerable risks. These findings demonstrate the complex and enduring impact of PFAS on environmental health, emphasizing the importance of this review in corroborating studies on sub-lethal toxicity in exposed organisms and how these effects reflect on the environment.

Biotic and abiotic transformations of aqueous film-forming foam (AFFF)-derived emerging polyfluoroalkyl substances in aerobic soil slurry

The severe contamination of per- and polyfluoroalkyl substances (PFAS) in aqueous film-forming foam (AFFF)-affected soil and groundwater has raised global concerns. Although extensive studies on the transformation of electrochemical fluorination (ECF)-based PFAS in soil exist, limited research on AFFF-derived emerging fluorotelomer (FT) compounds has been conducted. Herein, a total of 38 PFAS were identified in a composite AFFF formulation through suspect and nontarget screening using high-resolution mass spectrometry (HRMS), and emerging 6:2 FT compounds were particularly prominent. Subsequently, the composite AFFF formulation was introduced to aerobic soil slurry to investigate the transformation behaviors of nine high-abundance polyfluoroalkyl substances. After a 150-day incubation, polyfluorinated sulfonamide betaine and quaternary ammonium compounds showed significant recalcitrance. The tertiary amine- and thioether-based PFAS underwent biotic and abiotic transformations, with half-lives ranging from 2 to 56 days and from 38 to 248 days, respectively. On the basis of the products identified using HRMS, the transformation pathways of FT- and ECF-based PFAS were proposed. Notably, the hydroxylation of tertiary amines and the oxidation of thioethers were two major abiotic reactions. Toxicity prediction revealed that certain transformation products exhibited higher toxicity toward aquatic organisms compared with the parent compounds. This study provides valuable insights into the stability and transformation of emerging PFAS in aerobic soil.

Uncovering the effects of the North Pacific Subtropical Gyre on per- and polyfluoroalkyl substances distribution in the Tropical Western Pacific

The accumulation of per- and polyfluoroalkyl substances (PFAS) in subtropical gyres, commonly referred to as "garbage patches", remains insufficiently characterized. In this study, we collected surface seawater samples from 40 sites across the Tropical Western Pacific (TWP) and identified 19 different PFAS. Of them, perfluoro-n-butanoic acid (PFBA) exhibits the highest concentration (median 329.2 pg/L). The concentration of ΣPFAS in nearshore region (median 910.5 pg/L) is higher than those in two other oceanic regions (with medians of 773.8 pg/L in Philippine Sea and 863.1 pg/L in Equatorial Current, respectively). However, in North Pacific Subtropical Gyre (NPSG), the ΣPFAS concentration (median 1056.5 pg/L) is higher than that in the nearshore region and significantly higher than in North Equatorial Current (NEC) (p < 0.05) and the composition and concentrations of PFAS in this region significantly differ from those in other oceanic regions (p < 0.05). Additionally, PFBA, an alternative perfluoroalkyl carboxylic acid (PFCA), is significantly enriched in the NPSG (p < 0.05). These suggest that alternative PFAS have now become the main PFAS pollutants in the surface waters of TWP, with PFOA and its alternatives making up the majority. Enrichment of PFCA is observed in the surface seawater of NPSG, with enrichment factors influenced by chain length and human activities. This study provides the first comprehensive analysis of the distribution and migration characteristics of PFAS in TWP, emphasizing the influence of subtropical gyre on PFAS accumulation.

A stable dual-functional monomer imprinted polymer platform for electrochemical sensitive detection of PFAS

Electrochemical molecular imprinting technology (e-MIT) has gained significant attention for detecting emerging micropollutants like per- and polyfluoroalkyl substances (PFAS). However, designing efficient and reliable PFAS sensors based on e-MIT remains challenging. In this study, we explored a mechanism for synergistic adsorption recognition of dual-functional monomers (DM), based on which a molecularly imprinted electrochemical sensor with high sensitivity and stability was developed for PFOA detection. DFT simulations demonstrated that the synergistic interaction between DMs enhances both molecular adsorption capacity and structural stability. Response surface methodology was employed to optimize the MIP composition, revealing a strong correlation between the DM ratio and sensor performance. The optimized MIP-modified electrode exhibited a higher Langmuir adsorption coefficient (Kₐ = 8.92 × 10⁸ cm3 mol-1) and improved stability (RSD < 2 %) compared to single-functional monomer electrodes. Additionally, Al/Co-MOFs/rGO complexes are coupled as the sensor basement. The sensor displayed a wide linear detection range (10 pM to 100 nM), low detection limit (5 pM), and excellent recoveries (94 %-107 %) in river samples, demonstrating its robustness and reliability in real-world applications. This study highlights the potential of DM-based electrochemical sensors for sensitive and reliable detection of emerging micropollutants in complex water environments, paving the way for future monitoring and environmental protection.

Per- and polyfluoroalkyl substances mixture impairs intestinal barrier function through microbiota-derived 21-deoxycortisol and cortisol metabolism dysregulation

Per- and polyfluoroalkyl substances (PFASs) are persistent environmental pollutants linked to various health risks, including intestinal disorders. However, the effect of real-world PFASs mixture on intestinal health remains unclear. Therefore, this study aimed to investigate the effects of a PFASs mixture by mimicking the exposure composition in a population on intestinal homeostasis in rats. Although the colon showed no significant morphological alterations, transcriptomic analysis revealed dose-dependent changes in gene expression levels related to cell-cell and tight junctions. Immunofluorescence and immunohistochemistry further confirmed these findings, demonstrating a dose-dependent decrease in key tight junction proteins, occludin and claudin-1, in the colonic epithelium. Integrative analysis revealed that PFASs mixture exposure disrupted the growth and metabolism of gut bacteria, such as Ruminococcus, leading to increased production of 21-deoxycortisol (21-DF). 21-DF inhibited cortisol to cortisone conversion, elevating cortisol levels in intestinal epithelial cells. Consequently, the increased cortisol levels suppressed the expression of tight junction proteins and disrupted the intestinal barrier function. Our findings provide novel insights into the underlying mechanisms by which real-world PFASs mixture disrupt intestinal barrier function through the gut microbiome-metabolome-epithelial cell axis, highlighting the need to consider the complex interplay between environmental pollutants, gut microbiota, and host health in risk assessment and development of intervention strategies.

Towards a Better Understanding of the Human Health Risk of Per- and Polyfluoroalkyl Substances Using Organoid Models

The ubiquitous presence of per- and polyfluoroalkyl substances (PFAS) in the environment has garnered global public concern. Epidemiological studies have proved that exposure to PFAS is associated with human health risks. Although evidence demonstrated the toxic mechanisms of PFAS based on animal models and traditional cell cultures, their limitations in inter-species differences and lack of human-relevant microenvironments hinder the understanding of health risks from PFAS exposure. There is an increasing necessity to explore alternative methodologies that can effectively evaluate human health risks. Human organoids derived from stem cells accurately mimic the sophisticated and multicellular structures of native human organs, providing promising models for toxicology research. Advanced organoids combined with innovative technologies are expected to improve understanding of the breadth and depth of PFAS toxicity.

Per- and polyfluoroalkyl substances (PFAS) exposure in the U.S. population: NHANES 1999-March 2020

Per- and polyfluoroalkyl substances (PFAS), also known as "forever chemicals" because of their persistence in the environment, have been used in many commercial applications since the 1940s. Of late, the detection of PFAS in drinking water throughout the United States has raised public and scientific concerns. To understand PFAS exposure trends in the general U.S. population, we analyzed select PFAS serum concentration data from participants ≥12 years old of nine National Health and Nutrition Examination Survey (NHANES) cycles. Our goals were to a) evaluate concentration changes of four legacy PFAS-perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) from 1999 to 2000 to 2017-March 2020, b) discuss serum concentrations and assess demographic predictors of two PFAS measured for the first time in 2017-2018, perfluoro-1-heptanesulfonic acid (PFHpS) and 9-chlorohexadecafluoro-3-oxanonane-1-sulfonic acid (9CLPF), and c) compare concentration profiles of legacy PFAS in NHANES to profiles in exposed communities. We report a decrease in geometric mean concentrations of the four legacy PFAS (16%-87%, depending on the PFAS) from 1999 to 2000, although in 2017-March 2020, more than 96% of people aged 12-19 years, some of whom were born after PFAS production changes started in the early 2000s, had measurable concentrations of these PFAS. An estimated 78% of the U.S. general population had detectable concentrations of PFHpS, and 8% had detectable concentrations of 9CLPF (>44% of whom self-identified as Asian). Comparing profiles in NHANES and people living in communities with PFAS contamination can help identify exposure sources and evaluate and monitor exposures in select areas or among specific population groups. Collectively, our findings highlight the usefulness of NHANES data to help researchers, public health officials, and policy makers prioritize investigations, monitor exposure changes, and evaluate effectiveness of efforts to limit exposures.

Electrochemical destruction of PFAS at low oxidation potential enabled by CeO2 electrodes utilizing adsorption and activation strategies

The persistence and ecological impact of per- and poly-fluoroalkyl substances (PFAS) in water sources necessitate effective and energy-efficient treatment solutions. This study introduces a novel approach using cerium dioxide (CeO2) electrodes enhanced with oxygen vacancy (Ov) to catalyze the defluorination of PFAS. By leveraging the unique affinity between cerium and fluorine-containing species, our approach enables adsorptive preconcentration and catalytic degradation at low oxidation potentials (1.37 V vs. SHE). Demonstrating high removal and defluorination efficiencies of perfluorooctanoic acid (PFOA) at 94.0 % and 73.0 %, respectively, our approach also proves effective in the environmental matrix. It minimizes the impacts of co-existing natural organic matter and chloride ions, crucial benefits of operating at lower oxidation potentials. The role of Ov in CeO2 is validated by both experimental results and density functional theory modeling, demonstrating that these sites can activate the C-F bond and substantially reduce the energy barriers for defluorination. Consequently, our CeO2-based method not only achieves defluorination efficiencies comparable to more energy-intensive techniques but does so while requiring less than 0.62 kWh/m3 per order. This positions our approach as a promising, cost-effective alternative for the remediation of PFAS-contaminated waters, emphasizing its relevance and effectiveness in environmental remediation scenarios.

Addressing data gaps in deriving aquatic life ambient water quality criteria for contaminants of emerging concern: Challenges and the potential of in silico methods

The international community is becoming increasingly aware of the threats posed by contaminants of emerging concern (CECs) for ecological security. Aquatic life ambient water quality criteria (WQC) are essential for the formulation of risk prevention and control strategies for pollutants by regulatory agencies. Accordingly, we systematically evaluated the current status of WQC development for typical CECs through literature review. The results revealed substantial disparities in the WQC for the same chemical, with the coefficients of variation for all CECs exceeding 0.3. The reliance on low-quality data, high-uncertainty derivation methods, and limited species diversity highlights a substantial data gap. Newly developed in silico methods, with potential to predict the toxicity of untested chemicals, species, and conditions, were classified and integrated into a traditional WQC derivation framework to address the data gap for CECs. However, several challenges remain before such methods can achieve widespread acceptance. These include unstable model performance, the inability to predict chronic toxicity, undefined model applicability, difficulties in specifying toxicity effects and predicting toxicity for certain key species. Future research should prioritize: 1) improving model accuracy by developing specialized models trained with relevant, chemical-specific data or integrating chemical-related features into interspecies models; 2) enhancing species generalizability by developing multispecies models; 3) facilitating the derivation of environmentally relevant WQC by incorporating condition-related features into models; and 4) improving the regulatory acceptability of in silico methods by evaluating the reliability of "black-box" models.

Perfluorohexane Sulfonic Acid Disrupts the Immune Microenvironment for Spermatogenesis by Damaging the Structure of the Blood-Testis Barrier in Mice

Perfluorohexane sulfonic acid (PFHxS) is extensively used in waterproof coatings and fire-fighting foams, and several studies have found it to be a potential health hazard, but there is still unknown about its effects on spermatogenesis. Our results showed that PFHxS-treated mice have significant reproductive toxicity, including a decrease in sperm count and motility, and the levels of sex hormones (P < 0.05). Concurrently, structural abnormalities are observed in sperm, affecting ≈60-75% of those in the PFHxS-treated group. Additionally, it is found that the structure of the blood-testis barrier (BTB) is damaged after PFHxS treatment, leading to higher expression levels of inflammatory cytokines in the microenvironment for spermatogenesis. Moreover, the expression of proteins associated with mitochondrial biogenesis, including PTEN-induced kinase 1 (PINK1) and NADPH oxidase 4 (NOX4), is dysregulated in the testes after PFHxS treatment. Based on metabolome data, the differential metabolite 3-hydroxybutanoic acid is identified in the PFHxS-treated group, which can regulate the histone Kac levels, especially H3K4ac and H3K9ac. In summary, the results of this study suggest that in the testes of PFHxS-treated mice, inflammatory factors disrupt the mitochondrial function and metabolic profiles and hinder the progress of gene transcription through histone Kac, ultimately causing sperm dysfunction.

Presence and sources of per- and polyfluoroalkyl substances (PFASs) in the three major rivers on Hainan Island

Per- and polyfluoroalkyl substances (PFASs) have attracted considerable attention because of their toxicity, persistence and bioaccumulation potential. With the construction of the Hainan Free Trade Port and the rapid development of economy, environmental pollution on Hainan Island is becoming increasingly prominent. PFASs have been detected in the seawater and sediments of mangrove ecosystems on Hainan Island. As the receiving water of wastewater treatment plants (WWTPs) and industrial wastewater, rivers are inevitably contaminated by PFASs. However, few studies have focused on PFAS pollution in three large rivers (the Nandu, Changhua, and Wanquan rivers) on Hainan Island. In the present study, the pollution status, potential sources, and ecological risks of PFASs in these three major rivers were explored. Perfluorobutanonic acid (PFBA) (48.7%) was found to be the major PFASs in the surface waters, and perfluoroundecanoic acid (PFUnDA) (19.7%) was the major PFASs in the sediments of the three major rivers. The concentrations of ∑PFASs in the upper-midstream region were low due to minimal human influence and increased in the middle-lower reaches with increasing industrial activity and urbanization, whereas decreased at downstream sites near estuaries where river water was diluted with seawater. WWTP effluent, industrial wastewater discharge, the application and discharge of aqueous fire-fighting foam, storm runoff and landfill leachate were the major sources of PFASs in the three major rivers. In surface water, perfluorooctanoic acid (PFOA), perfluorooctane sulfonamide (PFOSA) and perfluorooctadecanoic acid (PFODA) posed low-moderate risks at 5.71-85.6% of the sampling sites. PFASs in the sediment posed no ecological risk. This study provides key data regarding the pollution status and potential sources of PFASs in large rivers on subtropical islands.

Identification of Novel Iodinated Polyfluoroalkyl Ether Acids and Other Emerging PFAS in Soils Using a Nontargeted Molecular Network Approach

Despite advancements in high-resolution screening techniques, the identification of novel perfluoroalkyl and polyfluoroalkyl substances (PFAS) remains challenging without prior structural information. In view of this, we proposed and implemented a new data-driven algorithm to calculate spectral similarity among PFAS, facilitating the generation of molecular networks to screen for unknown compounds. Using this approach, 81 PFAS across 12 distinct classes were identified in soil samples collected near an industrial park in Shandong Province, China, including the first reported occurrence of 12 iodine-substituted PFAS. Among them, the standards of four iodine-substituted polyfluorinated ether sulfonates (I-PFESA) were successfully synthesized, enabling structural confirmation and subsequent quantitative analysis. Although the median concentration of ∑I-PFESA (0.74 ng/g dw) in soil samples was lower than that of ∑H-PFESA (hydrogen-substituted, 61.96 ng/g dw) and ∑Cl-PFESA (chlorine-substituted, 2.98 ng/g dw), embryotoxicity assays in zebrafish revealed that 6:2 I-PFESA exhibited greater toxicity compared to 6:2 Cl-PFESA of the same chain length. This highlights the need for a closer examination of the toxic effects of I-PFESA. Notably, the proposed algorithm, based on novel PFAS spectral similarity, provides new perspectives on the environmental behavior and transformation of I-PFESA, although further investigation is required to elucidate the underlying mechanisms of their toxicity.

Streamlining Linear Free Energy Relationships of Proteins through Dimensionality Analysis and Linear Modeling

Linear free energy relationships (LFERs) are pivotal in predicting protein-water partition coefficients, with traditional one-parameter (1p-LFER) models often based on octanol. However, their limited scope has prompted a shift toward the more comprehensive but parameter-intensive Abraham solvation-based poly-parameter (pp-LFER) approach. This study introduces a two-parameter (2p-LFER) model, aiming to balance simplicity and predictive accuracy. We showed that the complex six-dimensional intermolecular interaction space, defined by the six Abraham solute descriptors, can be efficiently simplified into two key dimensions. These dimensions are effectively represented by the octanol-water (log Kow) and air-water (log Kaw) partition coefficients. Our 2p-LFER model, utilizing linear combinations of log Kow and log Kaw, showed promising results. It accurately predicted structural protein-water (log Kpw) and bovine serum albumin-water (log KBSA) partition coefficients, with R2 values of 0.878 and 0.760 and root mean squared errors (RMSEs) of 0.334 and 0.422, respectively. Additionally, the 2p-LFER model favorably compares with pp-LFER predictions for neutral per- and polyfluoroalkyl substances. In a multiphase partitioning model parametrized with 2p-LFER-derived coefficients, we observed close alignment with experimental in vivo and in vitro distribution data for diverse mammalian tissues/organs (n = 137, RMSE = 0.44 log unit) and milk-water partitioning data (n = 108, RMSE = 0.29 log units). The performance of the 2p-LFER is comparable to pp-LFER and significantly surpasses 1p-LFER. Our findings highlight the utility of the 2p-LFER model in estimating chemical partitioning to proteins based on hydrophobicity, volatility, and solubility, offering a viable alternative in scenarios where pp-LFER descriptors are unavailable.

Neurotoxicity of per- and polyfluoroalkyl substances: Evidence and future directions

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals widely used in various products, including food packaging, textiles, and firefighting foam, owing to their unique properties such as amphiphilicity and strong CF bonds. Despite their widespread use, concerns have arisen due to their resistance to degradation and propensity for bioaccumulation in both environmental and human systems. Emerging evidence suggests a potential link between PFAS exposure and neurotoxic effects, spanning cognitive deficits, neurodevelopmental disorders, and neurodegenerative diseases. This review comprehensively synthesizes current knowledge on PFAS neurotoxicity, drawing insights from epidemiological studies, animal experiments, and mechanistic investigations. PFAS, known for their lipophilic nature, tend to accumulate in lipid-rich tissues, including the brain, breaching biological barriers such as the blood-brain barrier (BBB). The accumulation of PFAS within the central nervous system (CNS) has been implicated in a spectrum of neurological maladies. Neurotoxicity induced by PFAS manifests through a multitude of direct and indirect mechanisms. A growing body of research associated PFAS exposure with BBB disruption, calcium dysregulation, neurotransmitter alterations, neuroinflammation, oxidative stress, and mitochondrial dysfunction, all contributing to neuronal impairment. Despite notable strides in research, significant lacunae persist, necessitating further exploration to elucidate the full spectrum of PFAS-mediated neurotoxicity. Prospective research endeavors should prioritize developing biomarkers, delineating sensitive exposure windows, and exploring mitigation strategies aimed at safeguarding neurological integrity within populations vulnerable to PFAS exposure.

Responses and mechanisms of perfluoroalkyl acid release to the cumulative effects of propeller jet force over time

As the discharge of exogenous perfluoroalkyl acids (PFAAs) is gradually controlled, the secondary release of endogenous PFAAs is poised to become a major challenge. However, the effects of complex hydrodynamic conditions, such as disturbance from ship propeller jets, on PFAA release, are still poorly understood. In the present study, a propeller jet disturbance simulation experiment was carried out using an indoor flume to investigate the responses and mechanisms of PFAA release to the cumulative effects of jet force over time. Although an increase in jet action time (t) increased the total amount of dissolved PFAAs in the overlying water, PFAA dissolution intensity decreased. Conversely, increase in t induced a rise in both total PFAA amount adsorbed and adsorption intensity in suspended particulate matter (SPM). Moreover, differences in functional groups and carbon-fluorine chain lengths resulted in different types of PFAAs exhibiting different sensitivities to changes in t during dissolution and adsorption. During the jet disturbance, there were distinct shear zoning and pressure gradients in the flow field, contributing to the tendency of PFAAs to be distributed in the overlying water. However, after the disturbance, PFAAs tended to distribute in the SPM. Changes in t consistently affected the partition behavior of long-chain PFAAs (C ≥ 7), whereas the effect on the partition behavior of short-chain PFAAs (C < 7) was rather short-lived. In contrast, Perfluoroalkyl carboxylic acids were more readily released from the sediments and porewater than Perfluoroalkyl sulfonic acids; however, the difference decreased with increasing t. Both shear impulse and squeeze impulse showed a significant linear positive correlation with PFAA release (p < 0.05), but the effect of shear impulse was greater. The findings provide perspectives for further understanding of PFAA release under jet disturbance and could facilitate endogenous PFAA contamination control.

A review of per- and polyfluoroalkyl substances (PFASs) removal in constructed wetlands: Mechanisms, enhancing strategies and environmental risks

PER: Polyfluoroalkyl substances (PFASs), typical persistent organic pollutants detected in various water environments, have attracted widespread attention due to their undesirable effects on ecology and human health. Constructed wetlands (CWs) have emerged as a promising, cost-effective, and nature-based solution for removing persistent organic pollutants. This review summarizes the removal performance of PFASs in CWs, underlying PFASs removal mechanisms, and influencing factors are also discussed comprehensively. Furthermore, the environmental risks of PFASs-enriched plants and substrates in CWs are analyzed. The results show that removal efficiencies of total PFASs in various CWs ranged from 21.3% to 98%. Plant uptake, substrate absorption and biotransformation are critical pathways in CWs for removing PFASs, which can be influenced by the physiochemical properties of PFASs, operation parameters, environmental factors, and other pollutants. Increasing dissolved oxygen supply and replacing traditional substrates in CWs, and combining CWs with other technologies could significantly improve PFASs removal. Further, CWs pose relatively lower ecological and environmental risks in removing PFASs, which indicates CWs could be an alternative solution for controlling PFASs in aquatic environments.

Impact of hexafluoropropylene oxide trimer acid (HFPO-TA) on sex differentiation after exposures during different development stages of zebrafish (Danio rerio)

Hexafluoropropylene oxide trimer acid (HFPO-TA), a novel alternative to perfluorooctanoic acid (PFOA), has been widely used and ubiquitously detected in aquatic environments. However, its potential effects on sex differentiation of aquatic organisms are not well known. Therefore, in this study, zebrafish were exposed to HFPO-TA at different development stages (0-21, 21-42, and 42-63 dpf) to investigate the effects on sex differentiation and its underlying mechanisms. All three exposures to HFPO-TA resulted in the feminization of zebrafish, and the impact of Stage II was most significant. The transcription levels of key genes related to female differentiation (bpm15, cyp19a1a, esr1, vtg1, and sox9b) were up-regulated, while those of key genes related to male differentiation (dmrt1, gata4, amh, and sox9a) were down-regulated, which could lead to the feminization. In addition, it was found that the dysregulations of these genes were prolonged in adult zebrafish even through a long recovery, which could cause sex imbalance in populations. Therefore, HFPO-TA might not be a safe alternative to PFOA, and more evidences from multi- and transgenerational toxicology are warranted.

Bioturbation Affects Bioaccumulation: PFAS Uptake from Sediments by a Rooting Macrophyte and a Benthic Invertebrate

Despite the widespread presence of per- and polyfluoroalkyl substances (PFAS) in freshwater environments, only a few studies have addressed their bioaccumulation in macrophytes and benthic invertebrates. This study therefore aimed at investigating the presence of 40 PFAS in sediments, assessing their bioaccumulation in a rooting macrophyte (Myriophyllum spicatum) and a benthic invertebrate (Lumbriculus variegatus) and examining the effects of the presence and bioturbation activity of the invertebrate on PFAS bioaccumulation in the plants. The macrophytes were exposed to sediments originating from a reference and a PFAS-contaminated site. The worms were introduced in half of the replicates, and at the end of the experiment, PFAS were quantified in all environmental compartments. Numerous targeted PFAS were detected in both sediments and taken up by both organisms, with summed PFAS concentrations in organisms largely exceeding concentrations in the original sediments. Bioaccumulation differed between organisms and the two sediments. The presence of the worms significantly reduced the PFAS concentrations in the plant tissues, but for some compounds, root bioaccumulation increased in the presence of the worms. This effect was most prominent for the degradable PFAS precursors. It is concluded that organisms affect the environmental fate of PFAS, emphasizing that contaminant-macroinvertebrate interactions are two-sided.

Adolescent F-53B exposure induces ovarian toxicity in rats: Autophagy-apoptosis interplay

As a substitute for perfluorooctane sulfonates, F-53B has permeated into the environment and can reach the human body through the food chain. Adolescent individuals are in a critical stage of development and may be more sensitive to the impacts of F-53B. In the present study, we modeled the exposure of adolescent female rats by allowing them free access to F-53B at concentrations of 0 mg/L, 0.125 mg/L, and 6.25 mg/L in drinking water, aiming to simulate the exposure in the adolescent population. Using the ovary as the focal point, we investigated the impact of developmental exposure to F-53B on female reproduction. The results indicated that F-53B induced reproductive toxicity in adolescent female rats, including ovarian lesions, follicular dysplasia and hormonal disorders. In-depth investigations revealed that F-53B induced ovarian oxidative stress, triggering autophagy within the ovaries, and the autophagy exhibited the interplay with apoptosis in turn, collectively leading to significant ovarian toxicity. Our findings provided deeper insights into the roles of the autophagy-apoptosis interplay in ovarian toxicity, and offered a new perspective on the developmental toxicity inflicted by adolescent F-53B exposure.

Submerge-emerge alternation promotes sediment per- and polyfluoroalkyl substance (PFAS) release and bioaccumulation

Understanding the sediment release and plant bioaccumulation of per- and polyfluoroalkyl substances (PFASs) under submerge-emerge alternation (SE) is crucial to predicting their transport and fate in the riparian zones. In the present study, a simulational device was firstly constructed to explore the effects of SE on the transport of PFASs in riparian sediment-plant systems and the underlying mechanisms. The submerge (CS) and emerge (CE) situations were compared. The results showed that SE significantly enhanced the transport and bioaccumulation of PFASs in sediments. Compared with the initial concentration, PFASs in sediments decreased by 81.84 %, 50.48 %, and 21.68 % in the SE, CS, and CE groups, respectively. The bioaccumulation of PFASs in plant roots in the SE group was 1.26 and 4.16 times higher than that in the CS and CE groups, respectively, and the bioaccumulation of PFASs in leaves in the SE group was 2.05 and 1.71 times higher than that in the other two groups. Dissolved organic matter (DOM) composition and molecular properties under SE were recognized as the dominant factors regulating the release of PFASs from sediments. Root morphology and low-molecular-weight organic acids (LMWOAs) in root exudates were closely associated with the bioaccumulation of PFASs in plants. Among the substitutes, hexafluoropropylene oxide trimer acid (HFPO-TA) demonstrated greater hydrophobicity, hexafluoropropylene oxide dimer acid (Gen-X) had greater mobility, and 6:2 fluorotelomer sulfonate (6:2 FTS) accumulated more in plants. This study has expanded the understanding of the geochemical cycling of PFASs in riparian sediment-plant systems under submerge-emerge alternation.

Occurrence of short- and ultra-short chain PFAS in drinking water from Flanders (Belgium) and implications for human exposure

SHORT: and ultra-short chain perfluoroalkyl substances (S- and US-PFAS) are alternatives for the long-chain PFAS which have been more regulated over time. They are highly mobile in the environment and can easily reach drinking water sources which can become an important human exposure route. Furthermore, there have been growing concerns about the presence of PFAS in Flanders. Because of this, human exposure to S- and US-PFAS through Flemish drinking water was evaluated in this study. For this purpose, the presence of 2 S-PFAS (PFBS and PFBA) and 5 US-PFAS (PFPrS, PFEtS, TFMS, PFPrA and TFA) was investigated in 47 tap water samples, collected from different Flemish provinces, and 16 bottled waters purchased in Flanders. Out of the 7 target PFAS, 4 (PFBA, PFBS, PFPrS and PFEtS) were detected at concentrations above LOQ in tap water. In bottled water, only TFMS was present above its LOQ. PFAS concentrations in all analyzed water samples ranged from <0.7 to 7.3 ng/L for PFBS, <0.03-15.0 ng/L for TFMS and <0.9-12.0 ng/L for PFBA. PFPrS was only detected once above its LOQ, at 0.6 ng/L. No value could be reported for PFPrA due to high procedural blanks resulting in a high LOQ, nor for TFA due to high matrix effect. No significant differences in PFAS concentrations were seen in tap water among different drinking water companies, provinces, nor between the two types of analyzed bottled water (natural mineral water vs spring water). The use of a commercial carbon filter significantly reduced the median concentrations of the studied compounds in tap water. Finally, it was estimated that the presence of S- and US-PFAS in Flemish drinking water does not pose an immediate threat to human health, as concentrations were at least two orders of magnitude below the available guidance values.

Combined environmental relevant exposure to perfluorooctanoic acid and zinc sulfate enhances apoptosis through binding with endogenous antioxidants in Daphnia magna

Perfluorooctanoic acid (PFOA) is a long-chain legacy congener of the per- and polyfluoroalkyl substances (PFAS) family, notorious as a "forever chemical" owing to its environmental persistence and toxic nature. Essential elements such as zinc (Zn) can cause toxic effects when they change their metal speciation and become bioavailable, such as zinc sulfate (ZnSO4). Combined toxicity assessment is a realistic approach and a challenging task to evaluate chemical interactions and associated risks. Therefore, the present study aims to elucidate the acute mixture toxicity (12-48 h) of PFOA and ZnSO4 in Daphnia magna at environment-relevant concentrations (ERCs, low dose: PFOA 10 μg/L ZnSO4 20 μg/L; high dose: PFOA 20 μg/L ZnSO4 50 μg/L) in terms of developmental impact, apoptosis induction, and interaction with major endogenous antioxidants. Our results showed that deformity rates significantly increased (p < 0.05) with increasing exposure duration and exposure concentrations, compared to the control group. Further, lack of antenna, tale degeneration, and carapace alterations were the most commonly observed deformities following combined exposure to PFOA and ZnSO4, and these malformations were particularly pronounced after 48 h of exposure. Acridine orange (AO) staining was employed to examine apoptosis in D. magna, and apoptotic cells in terms of bright green fluorescence were detected in the abdominal claw carapace, heart, and post-abdominal area following exposure to a high dose of PFOA and ZnSO4. The molecular docking results revealed that both PFOA and ZnSO4 showed strong binding affinities with endogenous antioxidants CAT and GST, where PFOA was more strongly bound with CAT and GST with higher docking scores of -9.59 kcal/mol and -7.49 kcal/mol than those with ZnSO4 (-6.70 kcal/mol and -6.55 kcal/mol, respectively). In conclusion, the mixture exposure to PFOA and ZnSO4 at the environmental level induce developmental impacts and apoptosis through binding with major endogenous antioxidants in D. magna.

Integrating redox-electrodialysis and electrosorption for the removal of ultra-short- to long-chain PFAS

A major challenge in per- and polyfluoroalkyl substances (PFAS) remediation has been their structural and chemical diversity, ranging from ultra-short to long-chain compounds, which amplifies the operational complexity of water treatment and purification. Here, we present an electrochemical strategy to remove PFAS from ultra-short to long-chain PFAS within a single process. A redox-polymer electrodialysis (redox-polymer ED) system leverages a water-soluble redox polymer with inexpensive nanofiltration membranes, facilitating the treatment of varied chain lengths of PFAS without membrane fouling. Our approach combines both ion migration by electrodialysis (for PFAS with chain lengths ≤C4) and electrosorption strategies (for PFAS with chain lengths ≥C6) to eliminate approximately 90% of ultra-short-, short-chain, and long-chain PFAS. At the same time, we achieve continuous desalination of the source water down to potable water level. The redox-polymer ED exhibits remarkable PFAS removal in real source water scenarios, including from matrices with 10,000 times higher salt concentrations, as well as secondary effluents from wastewaters. Additionally, the removed PFAS is mineralized with a defluorination performance between 76-100% by electrochemical oxidation, highlighting the viability of integrating the separation step with a reactive degradation process.

Legacy and alternative perfluoroalkyl acids in the Yellow River on the Qinghai-Tibet Plateau: Levels, spatiotemporal characteristics, and multimedia transport processes

The source region of the Yellow River (SRYR) located in the northeast of the Qinghai-Tibetan Plateau is not only the largest runoff-producing area in the Yellow River Basin, but also the most important freshwater-supply ecological function area in China. In this study, the short-term spatiotemporal distribution of selected legacy and alternative perfluoroalkyl acids (PFAAs) in the SRYR was first investigated in multiple environmental media. Total PFAA concentrations were in the range of 1.16-14.3 ng/L, 4.25-42.1 pg/L, and 0.21-13.0 pg/g dw in rainwater, surface water, and sediment, respectively. C4-C7 PFAAs were predominant in various environmental matrices. Spatiotemporal characteristics were observed in the concentrations and composition profiles. Particularly, the spatial distribution of rainwater and the temporal distribution of surface water exhibited highly significant differences (p<0.01). Indian monsoon, westerly air masses, and local mountain-valley breeze were the driving factors that contributed to the change of rainwater. Rainwater, meltwater runoff, and precursor degradation were important sources of PFAA pollution in surface water. Organic carbon content was a major factor influencing PFAA distribution in sediment. These results provide a theoretical basis for revealing the regional transport and fate of PFAAs, and are also important prerequisites for effectively protecting the freshwater resource and aquatic environment of the Qinghai-Tibetan Plateau.

Exploring the environmental contamination toxicity and potential carcinogenic pathways of perfluorinated and polyfluoroalkyl substances (PFAS): An integrated network toxicology and molecular docking strategy

The objective of this study was to investigate the potential carcinogenic toxicity and mechanisms of PFAS in thyroid, renal, and testicular cancers base on network toxicology and molecular docking techniques. Structural modeling was performed to predict relevant toxicity information, and compounds and cancer-related targets were screened in multiple databases. The interaction of PFAS with three cancers and their key protein targets were explored by combining protein network analysis, enrichment analysis and molecular docking techniques. PFOA, PFOS, and PFHXS exhibited significant carcinogenic and cytotoxic effects. These compounds may induce cancer by mediating active oxygen metabolism and the transduction of phosphatidylinositol 3-kinase/protein kinase B signaling pathway through genes such as ALB, mTOR, MDM2, and ERBB2. Furthermore, the underlying toxic mechanisms may be linked to the pathways in cancer, chemical carcinogenesis through reactive oxygen species/receptor activation, and the FoxO signaling pathway. The results contribute to a comprehensive understanding of the effects of these environmental pollutants on genes, proteins, and metabolic pathways in living organisms. It revealed their toxicity mechanisms in inducing thyroid, renal, and testicular cancers, and provided a solid theoretical foundation for designing new environmental control strategies and drug screening initiatives. Additionally, the integrated application of network toxicology and molecular docking technology can enhance our understanding of the toxicity and mechanisms of unknown environmental pollutants, which is beneficial for protecting the environment and human health.

Comparative toxicity assessment of alternative versus legacy PFAS: Implications for two primary trophic levels in freshwater ecosystems

Perfluoroalkyl substances (PFAS) are common environmental pollutants, but their toxicity framework remains elusive. This research focused on ten PFAS, evaluating their impacts on two ecotoxicologically relevant model organisms from distinct trophic levels: the crustacean Daphnia magna and the unicellular green alga Raphidocelis subcapitata. The results showed a greater sensitivity of R. subcapitata compared to D. magna. However, a 10-day follow-up to the 48 h immobilisation test in D. magna showed delayed mortality, underlining the limitations of relying on EC50 s from standard acute toxicity tests. Among the compounds scrutinized, Perfluorodecanoic acid (PFDA) was the most toxic to R. subcapitata, succeeded by Perfluorooctane sulfonate (PFOS), Perfluorobutanoic acid (PFBA), and Perfluorononanoic acid (PFNA), with the latter being the only one to show an algicidal effect. In the same species, assessment of binary mixtures of the compounds that demonstrated high toxicity in the single evaluation revealed either additive or antagonistic interactions. Remarkably, with an EC50 of 31 mg L-1, the short-chain compound PFBA, tested individually, exhibited toxicity levels akin to the notorious long-chain PFOS, and its harm to freshwater ecosystems cannot be ruled out. Despite mounting toxicological evidence and escalating environmental concentrations, PFBA has received little scientific attention and regulatory stewardship. It is strongly advisable that regulators re-evaluate its use to mitigate potential risks to the environmental and human health.

Legacy and emerging per- and polyfluoroalkyl substances (PFASs) in agricultural soils affected by fluorochemical manufacturing facilities, North China: Occurrence, region-specific distribution, substitution trend and source appointment

Accompanied with restriction of legacy per- and polyfluoroalkyl substances (PFASs), numbers of emerging PFASs are widely detected in the environment. However, information on environmental occurrences and behaviors of emerging PFASs were scarce in agricultural soils. In this study, the spatial distributions, sources, substitution trends and ecological risk assessment of 31 legacy and emerging PFASs were investigated in 69 agricultural soils from Fuxin, North China. The 26 out of 31 PFASs were detected with concentrations of 57.36 - 1271.06 pg/g dry weight. Perfluorooctanoic acid (PFOA) and hexafluoropropylene oxide dimer acid (HFPO-DA) were predominant in legacy and emerging PFASs, respectively. Based on principal component and dual carbon-nitrogen stable isotope analysis, atmosphere, fluorochemical activities and river irrigation were main sources of PFASs. Substitution trends indicated HFPO-DA and short chain perfluoroalkyl carboxylic acids (C4 - C7) as main alternatives of PFOA, and 6:2 fluorotelomer sulfonic acid (6:2 FTSA) and sodium p-perfluorous nonenoxybenzene sulfonate (OBS) as major substitutes to perfluorooctanesulfonic acid (PFOS). The calculated risk quotient values (< 0.006) only indicated potential low ecological risk of 7 target PFASs in agricultural soils. The results of this study broadened out the information of PFAS contamination in agricultural soils, which were significant for PFAS supervision in China.

Comparative analysis of UV-initiated ARPs for degradation of the emerging substitute of perfluorinated compounds: Does defluorination mean the sole factor?

Due to the increasing attention for the residual of per- and polyfluorinated compounds in environmental water, Sodium p-Perfluorous Nonenoxybenzenesulfonate (OBS) have been considered as an alternative solution for perfluorooctane sulfonic acid (PFOS). However, recent detections of elevated OBS concentrations in oil fields and Frontal polymerization foams have raised environmental concerns leading to the decontamination exploration for this compound. In this study, three advanced reduction processes including UV-Sulfate (UV-SF), UV-Iodide (UV-KI) and UV-Nitrilotriacetic acid (UV-NTA) were selected to evaluate the removal for OBS. Results revealed that hydrated electrons (eaq-) dominated the degradation and defluorination of OBS. Remarkably, the UV-KI exhibited the highest removal rate (0.005 s-1) and defluorination efficiency (35 %) along with the highest concentration of eaq- (K = -4.651). Despite that nucleophilic attack from eaq- on sp2 carbon and H/F exchange were discovered as the general mechanism, high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC/Q-TOF-MS) analysis with density functional theory (DFT) calculations revealed the diversified products and routes. Intermediates with lowest fluorine content for UV-KI were identified, the presence nitrogen-containing intermediates were revealed in the UV-NTA. Notably, the nitrogen-containing intermediates displayed the enhanced toxicity, and the iodine poly-fluorinated intermediates could be a potential-threat compared to the superior defluorination performance for UV-KI.

Natural mineral and industrial solid waste-based adsorbent for perfluorooctanoic acid and perfluorooctane sulfonate removal from surface water: Advances and prospects

PER: and polyfluorinated alkyl substances, especially perfluorooctanoic acid and perfluorooctane sulfonic acid (PFOX), have attracted considerable attention lately because of their widespread occurrence in aquatic environment and potential biological toxicity to animals and human beings. The development of economical, efficient, and engineerable adsorbents for removing PFOX in water has become one of the research focuses. This review summarized the recent progress on natural mineral and industrial solid based adsorbent (NM&ISW-A) and removal mechanisms concerning PFOX onto NM&ISW-A, as well as proposed the current challenges and future perspectives of using NM&ISW-A for PFOX removal in water. Kaolinite and montmorillonite are usually used as model clay minerals for PFOX removal, and have been proved to adsorb PFOX by ligand exchange and electrostatic attraction. Fe-based minerals, such as goethite, magnetite, and hematite, have better PFOX adsorption capacity than clay minerals. The adsorbent prepared from industrial solid waste by high temperature roasting has great potential application prospects. Fabricating nanomaterials, amination modification, surfactant modification, fluorination modification, developing versatile composites, and designing special porous structure are beneficial to improve the adsorption performance of PFOX onto NM&ISW-A by enhancing the specific surface area, positive charge, and hydrophobicity. Electrostatic interaction, hydrophobic interaction, hydrogen bond, ligand and ion exchange, and self-aggregation (formation of micelle or hemimicelle) are the main adsorption mechanisms of PFOX by NM&ISW-A. Among them, electrostatic and hydrophobic interactions play a considerable role in the removal of PFOX by NM&ISW-A. Therefore, NM&ISW-A with electrostatic functionalities and considerable hydrophobic segments enables rapid, efficient, and high-capacity removal of PFOX. The future directions of NM&ISW-A for PFOX removal include the preparation and regeneration of engineerable NM&ISW-A, the development of coupling technology for PFOX removal based on NM&ISW-A, the in-depth research on adsorption mechanism of PFOX by NM&ISW-A, as well as the development of NM&ISW-A for PFOX alternatives removal. This review paper would be helpful the comprehensive understanding of NM&ISW-A potential for PFOX removal and the PFOX removal mechanisms, and identifies the gaps for future research and development.

Interaction of microplastics with perfluoroalkyl and polyfluoroalkyl substances in water: A review of the fate, mechanisms and toxicity

It is well known that microplastics can act as vectors of pollutants in the environment and are widely spread in freshwater and marine environments. PFAS (perfluoroalkyl and polyfluoroalkyl substances) can remain in the aqueous environment for long periods due to their wide application and good stability. The coexistence of microplastics and PFAS in the aqueous environment creates conditions for their interaction and combined toxicity. Studies on adsorption experiments between them and combined toxicity have been documented in the literature but have not been critically summarized and reviewed. Therefore, in this review, we focused on the interaction mechanisms, influencing factors, and combined toxicity between microplastics and PFAS. It was found that surface complexation may be a new interaction mechanism between microplastics and PFAS. In addition, aged microplastics reduce the adsorption of PFAS due to the presence of oxygenated groups on the surface compared to virgin microplastics. Attached biofilms can increase the adsorption capacity and create conditions for biodegradation. And, the interaction of microplastics and PFAS affects their spatial and temporal distribution in the environment. This review can provide insights into the fate of microplastics and PFAS in the global aquatic environment, fill knowledge gaps on the interactions between microplastics and PFAS, and provide a basic reference for assessing their combined toxicity.

Emerging organic contaminants in drinking water systems: Human intake, emerging health risks, and future research directions

Few earlier reviews on emerging organic contaminants (EOCs) in drinking water systems (DWS) focused on their detection, behaviour, removal and fate. Reviews on multiple exposure pathways, human intake estimates, and health risks including toxicokinetics, and toxicodynamics of EOCs in DWS are scarce. This review presents recent advances in human intake and health risks of EOCs in DWS. First, an overview of the evidence showing that DWS harbours a wide range of EOCs is presented. Multiple human exposure to EOCs occurs via ingestion of drinking water and beverages, inhalation and dermal pathways are discussed. A potential novel exposure may occur via the intravenous route in dialysis fluids. Analysis of global data on pharmaceutical pollution in rivers showed that the cumulative concentrations (μg L-1) of pharmaceuticals (mean ± standard error of the mean) were statistically more than two times significantly higher (p = 0.011) in South America (11.68 ± 5.29), Asia (9.97 ± 3.33), Africa (9.48 ± 2.81) and East Europe (8.09 ± 4.35) than in high-income regions (2.58 ± 0.48). Maximum cumulative concentrations of pharmaceuticals (μg L-1) decreased in the order; Asia (70.7) had the highest value followed by South America (68.8), Africa (51.3), East Europe (32.0) and high-income regions (17.1) had the least concentration. The corresponding human intake via ingestion of untreated river water was also significantly higher in low- and middle-income regions than in their high-income counterparts. For each region, the daily intake of pharmaceuticals was highest in infants, followed by children and then adults. A critique of the human health hazards, including toxicokinetics and toxicodynamics of EOCs is presented. Emerging health hazards of EOCs in DWS include; (1) long-term latent and intergenerational effects, (2) the interactive health effects of EOC mixtures, (3) the challenges of multifinality and equifinality, and (4) the Developmental Origins of Health and Disease hypothesis. Finally, research needs on human health hazards of EOCs in DWS are presented.