Emerging poly- and perfluoroalkyl substances in the aquatic environment: A review of current literature

Insights into the neurotoxicity and oxidative stress to the freshwater amphipod Hyalella azteca induced by hexafluoropropylene oxide trimer acid

With the regulation and phase-out of conventional per- and polyfluoroalkyl substances (PFAS), there is a growing trend towards seeking alternatives that are less toxic and less persistent. Hexafluoropropylene oxide trimer acid (HFPO-TA) is one of the alternatives to perfluorooctanoic acid (PFOA), the latter being widely present in the environment globally. However, there is limited information regarding the biological toxicity of HFPO-TA to aquatic organisms. In this study, the freshwater benthic amphipod, Hyalella azteca, was used to assess the acute and chronic toxicity of HFPO-TA in both water and sediment. HFPO-TA was found to be more toxic to H. azteca than PFOA, as indicated by greater production of reactive oxygen species (p < 0.05) and increasing catalase activity (p < 0.05). In addition, exposure to HFPO-TA affected the swimming behavior and the acetylcholinesterase (AChE) activity of the amphipod. Molecular docking models revealed that HFPO-TA can bind to AChE with a stronger binding affinity than PFOA. Furthermore, an integrated biomarker response index indicated that environmentally relevant concentration (1-100 μg/L) of HFPO-TA may cause toxicity to H. azteca, encompassing oxidative stress and neurotoxicity. This study provides new insights into the toxicity mechanisms of HFPO-TA and is valuable for assessing the ecological safety of this compound.

Rapid detection of perfluorooctanoic acid by surface enhanced Raman spectroscopy and deep learning

Perfluorooctanoic acid (PFOA) has received increasing concerns in recent years due to its wide distribution and potential toxicity. Existing detection techniques of PFOA require complex pre-treatment, therefore often taking several hours. Here, we developed a rapid PFOA detection mode to detect approximate concentrations of PFOA (ranging from 10-15 to 10-3 mol/L) in deionized water, and detecting one sample takes only 20 min. The detection mode was achieved using a deep learning model trained by a large surface enhanced Raman spectra dataset, based on the agglomeration of PFOA with crystal violet. In addition, transfer learning approach was used to fine tune the model, the fine-tuned model was generalizable across water samples with different impurities and environments to determine whether meet the safety standards of PFOA, the accuracy was 96.25 % and 94.67 % for tap water and lake water samples, respectively. The mechanism and specificity of the detection mode were further confirmed by molecular dynamics simulation. Our work provides a promising solution for PFOA detection, especially in the context of the increasingly widespread application of PFOA.

Innovative techniques for combating a common enemy forever chemicals: A comprehensive approach to mitigating per- and polyfluoroalkyl substances (PFAS) contamination

The pervasive presence of per and polyfluoroalkyl substances (PFAS), commonly referred to as "forever chemicals," in water systems poses a significant threat to both the environment and public health. PFAS are persistent organic pollutants that are incredibly resistant to degradation and have a tendency to accumulate in the environment, resulting in long-term contamination issues. This comprehensive review delves into the primary impacts of PFAS on both the environment and human health while also delving into advanced techniques aimed at addressing these concerns. The focus is on exploring the efficacy, practicality, and sustainability of these methods. The review outlines several key methods, such as advanced oxidation processes, novel materials adsorption, bioremediation, membrane filtration, and in-situ chemical oxidation, and evaluates their effectiveness in addressing PFAS contamination. By conducting a comparative analysis of these techniques, the study aims to provide a thorough understanding of current PFAS remediation technologies, as well as offer insights into integrated approaches for managing these persistent pollutants effectively. While acknowledging the high efficiency of adsorption and membrane filtration in reducing persistent organic pollutants due to their relatively low cost, versatility, and wide applicability, the review suggests that the integration of these methods could result in an overall enhancement of removal performance. Additionally, the study emphasizes the need for researcher attention in key areas and underscores the necessity of collaboration between researchers, industry, and regulatory authorities to address this complex challenge.

Cation-Doped Nanocarbons for Enhanced Perfluoroalkyl Substance Removal: Exotic Bottom-Up Solution Plasma Synthesis and Characterization

Perfluorinated alkyl substances (PFAS), such as perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), are pervasive organic contaminants that are widespread in aquatic environments, posing significant health risks to humans and wildlife. Due to their persistent nature, urgent removal is necessary. Conventional adsorbents are inefficient at removing PFOS and PFOA, highlighting the need for alternative materials. Herein, we present a synthetic method for quaternary ammonium cation-doped carbon nanoparticles (QACNs) using a solution plasma process for the efficient removal of PFOS and PFOA. QACN is formed simultaneously through a one-step discharge of nonequilibrium plasma at the interface of benzene and pyridinium chloride. The resulting material exhibited a high surface electrical charge and enhanced hydrophilicity as well as an amorphous structure of a nonporous nature, involving nanoparticles with an undefined shape. The obtained adsorbent demonstrated high adsorption efficiency and stability, adsorbing 998.45 and 889.37 mg g-1 of PFOS and PFOA, respectively, exceeding the efficiencies of conventional carbon-based adsorbents (80.89-313.15 mg g-1). The adsorption performance was dependent on the adsorbent dosage, pH of the solution, and the coexisting ionic species. Adsorption studies, including adsorption kinetics, isotherms, and thermodynamics, revealed that PFOS and PFOA were chemisorbed to the QACN surface, forming multilayers endothermically and spontaneously. Experimental and computational analyses revealed that adsorption primarily occurs via electronic interactions between the PFAS active sites and the quaternary ammonium group in the carbon framework. The slightly lower adsorption potential of the PFOS and PFOA fluorocarbon chains on the adsorbent was elucidated. Furthermore, the dispersibility of the adsorbent in solution significantly affected the adsorption performance. These findings highlight the potential of the novel synthetic method proposed in this study, offering a pathway for the development of highly effective carbon adsorbents for environmental remediation.

Occurrence, transformation, and transport of PFAS entering, leaving, and flowing past wastewater treatment plants with diverse land uses

Per- and polyfluoroalkyl substances (PFAS) have been detected ubiquitously throughout the environment. Wastewater treatment plants (WWTPs) have been identified as potential hotspots for the introduction of PFAS into the environment. Therefore, the occurrence, transformation, and transport of 18 PFAS in two WWTPs with varying treatment processes, prevailing land uses, and during two distinct time periods were investigated. Polar Organic Chemical Integrative Samplers (POCIS) were installed at two WWTPs in Central Kentucky during April and July of 2022. PFAS concentrations typically increased from influent to effluent at both WWTPs, regardless of wastewater treatment processes, but changes in surface water concentrations from upstream to downstream of the effluent mixing zones varied. Both WWTPs discharged the 18 PFAS at higher loads than received, indicating prevalent transformation of PFAS precursors and non-measured PFAS analytes into measurable PFAS. Nearly all measured PFAS persisted in aqueous (86-98%) compartments rather than sediment or biosolids (2-14%). All biosolids had low content of PFAS with the dominant compound being PFOS (1.59-2.60 ng/g). Based on recent US EPA proposed maximum contaminant levels, hazard indexes for drinking water were exceeded in effluent and downstream surface waters at both WWTPs. The WWTP located in a heavily developed area and downstream from a firefighting training facility, had significantly higher concentrations of most PFAS species at most monitoring sites and was less impacted by sampling period compared to the WWTP located in a moderately developed, pastured area. Findings support the importance of WWTPs and land use practices as contributing to PFAS impact to downstream ecosystems along with potentially increasing strains on downstream drinking water source waters in regions that are surface water dependent.

Ab Initio Investigation of Per- and Poly-fluoroalkyl Substance (PFAS) Adsorption on Zerovalent Iron (Fe0)

In this study, dispersion-corrected density functional theory (DFT) calculations were employed to investigate the adsorption of per- and poly-fluoroalkyl substances (PFAS) onto zerovalent iron (Fe0). The main objective of this investigation was to shed light on the adsorption properties, including adsorption energies, geometries, and charge transfer mechanisms, for four PFAS molecules, namely, perfluorooctanesulfonic acid (PFOS), perfluorobutanesulfonic acid (PFBS), perfluorooctanoic acid (PFOA), and perfluorobutanoic acid (PFBA), on the most thermodynamically accessible Fe0 surface facets. Additionally, the DFT investigation examined the role of PFAS chain length, functional group, protonation/deprotonation state, and solvation in water in their adsorption to Fe0. Overall, the adsorption of the four PFAS molecules on various Fe0 surfaces exhibited thermodynamically favorable energetics. Nevertheless, solvation in water resulted in less exothermic adsorption energies, and the presence of preadsorbed oxygen blocked the Fe0 surface, preventing PFAS adsorption. Additionally, the inclusion of a monolayer of Ni on top of the Fe0 surface reduced the stability of PFAS adsorption compared to pristine Fe0. Results of the computational investigation were compared to experimental results from the literature for qualitative validation.

Effect of physicochemical parameters on the occurrence of per- and polyfluoroalkyl substances (PFAS) in aquatic environment

Perfluoroalkyl substances (PFAS) and their distribution in aquatic environments have been studied extensively, but more information is needed to link these occurrences to their physicochemical characteristics. Understanding how these parameters influence PFAS can help predict their fate, mobility, and occurrences in water. This study reviewed the influence of physicochemical parameters on the occurrences of PFAS in aquatic environment using the relevant keywords to retrieve articles from databases spanning mostly between 2017 and 2024. The result suggests that high pH, turbidity, and dissolved oxygen, give high concentration of PFAS, while high electrical conductivity, temperature and salinity give low PFAS concentration in the water. Therefore, monitoring and safeguarding the aquatic bodies for human and environmental safety is imperative. Future studies should include the effects of the physicochemical properties on PFAS occurrences in the natural environment and focus on an organism's distinctive characteristics to comprehend the bioaccumulation and biomagnification of PFAS in them and environmental matrices.

Differential uptake and translocation of perfluoroalkyl substances by vegetable roots and leaves: Insight into critical influencing factors

Crop contamination of perfluoroalkyl substances (PFASs) may threaten human health, with root and leaves representing the primary uptake pathways of PFASs in crops. Therefore, it is imperative to elucidate the uptake characteristics of PFASs by crop roots and leaves as well as the critical influencing factors. In this study, the uptake and translocation of PFASs by roots and leaves of pak choi and radish were systematically explored based on perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), and perfluorooctane sulfonate (PFOS). Additionally, the roles of root Casparian strips, leaf stomata, and PFAS structures in the aforementioned processes were elucidated. Compared with pak choi, PFASs are more easily transferred to leaves after root uptake in radish, resulting from the lack of root Casparian strips. In pak choi root, the bioaccumulation of C4-C8 perfluoroalkyl carboxylic acids (PFCAs) showed a U-shaped trend with the increase of their carbon chain lengths, and the translocation potentials of individual PFASs from root to leaves negatively correlated with their chain lengths. The leaf uptake of PFOA in pak choi and radish mainly depended on cuticle sorption, with the evidence of a slight decrease in the concentrations of PFOA in exposed leaves after stomatal closure induced by abscisic acid. The leaf bioaccumulation of C4-C8 PFCAs in pak choi exhibited an inverted U-shaped trend as their carbon chain lengths increased. PFASs in exposed leaves can be translocated to the root and then re-transferred to unexposed leaves in vegetables. The longer-chain PFASs showed higher translocation potentials from exposed leaves to root. PFOS demonstrated a higher bioaccumulation than PFOA in crop roots and leaves, mainly due to the greater hydrophobicity of PFOS. Planting root vegetables lacking Casparian strips is inadvisable in PFAS-contaminated environments, in view of their higher PFAS bioaccumulation and considerable human intake.

Distribution and bioaccumulation of per- and polyfluoroalkyl substances (PFASs) in the Kuroshio Extension region of Northwest Pacific Ocean

Per- and polyfluoroalkyl substances (PFASs) are prevalently present in oceans, posing potential health risks to organisms and humans. However, information of PFAS distribution in remote open oceans is limited. In the Kuroshio Extension region of Northwest Pacific Ocean (6 stations), samples of 84 seawater (0-5800 m), 9 sediments, and 9 organisms were taken, and 25, 10, and 15 out of 29 PFASs were identified, respectively, with perfluorooctanoic acid (PFOA) and perfluorooctane sulfonates (PFOS) as the most dominant PFASs. In seawater, ΣPFASs concentration decreased from the Kuroshio region (4.47 ng/L) to the Oyashio region (3.15 ng/L), and decreased with increasing seawater depth under the function of biological and physical pumps. Additionally, 12 precursors and emerging PFASs, including perfluorooctane sulfonamide (FOSA, 0.20 ng/L), were detected. In sediment, PFASs (5.92-12.97 pg/g) were identified at depths exceeding 5000 m, including 3 precursors (e.g., FOSA, 0.82 pg/g). ΣPFASs contents were 27.12, 31.47 and 36.97 ng/g (dry weight) in brown algae (Phaeophyceae), barnacles (Balanus), and lanternfish (Myctophiformes), respectively, in which two precursors (e.g., FOSA, 0.09-0.12 ng/g) were also identified. A correlation with the trophic position was found for PFOA bioaccumulation. These findings provide useful information on PFAS distribution in the global open ocean environments.

Integrated non-targeted metabolomics and lipidomics reveal mechanisms of fluorotelomer sulfonates-induced toxicity in human hepatocytes

Fluorotelomer sulfonates (FTSs) are widely used as novel substitutes for perfluorooctane sulfonate, inevitably leading to FTSs accumulation in various environmental media and subsequent exposure to humans. This accumulation eventually poses environmental hazards and health risks. However, their toxicity mechanisms remain unclear. Herein, the mechanisms of two FTSs (6:2 and 8:2 FTS) induced toxicity in human hepatocellular carcinoma cells were investigated via non-targeted metabolomics and lipidomics based on liquid chromatography-high resolution mass spectrometry. Our results revealed that amino acid, purine, acylcarnitine and lipid levels were significantly perturbed by 6:2 and 8:2 FTS exposure. The effects of 8:2 FTS exposure were largely characterized by up-regulation of pyruvate metabolism pathway and down-regulation of purine metabolism pathway, whereas the opposite trends were induced by 6:2 FTS exposure. The opposite trends were confirmed by the mRNA expression levels of four key genes (glyoxalase 1, adenylosuccinate lyase, inosine monophosphate dehydrogenase 1 (IMPDH1) and IMPDH2) determined by real-time PCR. Common lipid perturbations included significantly increased ceramide/sphingomyelin ratios, and obvious accumulation of hexosylceramides and lysoglycerophospholipids. 6:2 FTS exposure induced sharp accumulation of glycerides, including monoglycerides, diglycerides and triglycerides. 8:2 FTS exposure induced decreased levels of acylcarnitines and fatty acids. Both of 6:2 and 8:2 FTS exposure induced increased levels of intracellular reactive oxygen species, an imbalance in energy metabolism homeostasis, and mitochondrial dysfunction. The results of integrated omics analysis are expected to serve as valuable information for the health risk assessment of 6:2 FTS and 8:2 FTS.

Unveiling the Molecular Effects of Replacement and Legacy PFASs: Transcriptomic Analysis of Zebrafish Embryos Reveals Surprising Similarities and Potencies

The prevalence of per- and poly fluoroalkyl substances (PFASs) in the environment has prompted restrictions on legacy PFASs due to their recognized toxic effects. Consequently, alternative "replacement" PFASs have been introduced and are prevalent in environmental matrices. Few studies have investigated the molecular effects of both legacy and replacement PFASs under short-term exposures. This study aimed to address this by utilizing transcriptomic sequencing to compare the molecular impacts of exposure to concentrations 0.001-5 mg/L of the legacy PFOS and two of its replacements, PFECHS and FBSA. Using zebrafish embryos, the research assessed apical effects (mortality, morphology, and growth), identified differentially expressed genes (DEGs) and enriched pathways, and determined transcriptomic points of departure (tPoDs) for each compound. Results indicated that PFOS exhibited the highest relative potency, followed by PFECHS and then FBSA. While similarities were observed among the ranked DEGs across all compounds, over-representation analysis revealed slight differences. Notably, PFOS demonstrated the lowest tPoD identified to date. These findings raise concerns regarding the safety of emerging replacement PFASs and challenge assumptions about PFAS toxicity solely resulting from their accumulative potential. As replacement PFASs proliferate in the environment, this study underscores the need for heightened scrutiny of their effects and questions current regulatory thresholds.

Quantitative assessment of poly- and perfluoroalkyl substances (PFASs) in aqueous film forming foam (AFFF)-impacted soils: a comparison of analytical protocols

Quantitatively assessing all per- and poly fluoroalkyl substances (PFASs) in an environmental sample, particularly soils impacted by aqueous film forming foams (AFFFs), has proven to be a challenge. To make such an assessment, a comprehensive sample processing procedure and analytical tool must be used. However, doubts remain whether current analytical tools such as high-resolution mass spectrometry (HRMS) with targeted quantitation and semi-quantitative analysis of suspects (Semi-Q HRMS) or total organic fluorine (TOF) are capable of accurately quantifying all non-polymeric PFASs in a sample. Further, current comprehensive soil PFAS HRMS methods are incompatible with TOF, preventing direct comparisons of the approaches. To enable direct comparisons, a soil sample processing procedure that is comprehensive as well as compatible with multiple analytical tools is needed. In this study, we assessed the performance of a previously developed soil PFAS method, EPA Method 1633, and a hybrid solid phase extraction (SPE)-based method for characterizing AFFF-impacted soil composites while maintaining compatibility with multiple analytical tools (i.e., Semi-Q HRMS and TOF). Comparative results for AFFF-impacted soil composites indicate analysis via EPA Method 1633 (as compared to the novel hybrid method) results in maybe up to 75% of the PFAS mass being missed by only analyzing for compounds listed in EPA Method 1633. Simply expanding the EPA Method 1633 analyte list was insufficient to account for the missing mass: up to 69% of the PFAS mass was still missed because of EPA Method 1633's extraction and cleanup bias. Additionally, the novel method developed offers a more comprehensive analysis with minimal reductions to sensitivity when compared to those reported in EPA Method 1633, with limits of quantification ranging from 0.12 to 2.4 ng/g as compared to 0.16-4.0 ng/g, respectively. For these reasons, an alternative hybrid SPE-based method is proposed for comprehensive evaluation of PFASs in AFFF-impacted soils.

Microplastic and associated emerging contaminants in marine fish from the South China Sea: Exposure and human risks

Microplastics can act as vectors of chemical contaminants in aquatic environments, but the extent to which this phenomenon contributes to chemical exposure in marine organisms remains poorly understood. We investigated the occurrence of microplastics and emerging contaminants (ECs), including antibiotics and per- and polyfluoroalkyl substances (PFAS) in 14 marine fish species. Microplastics were detected in all marine fish species, mainly in the gastrointestinal tract. Fluoroquinolones and tetracyclines were the dominant antibiotics in fish muscles with maximum concentrations of 24.84 and 26.95 ng g-1 ww, while perfluorooctanesulfonic acid (PFOS, 0.039-0.95 ng g-1 ww) was the dominant component in the PFAS profile. Fish with more microplastics had significantly higher concentrations of fluoroquinolones and perfluoroalkyl acids than fish with less microplastics (p < 0.05), but the correlation was not observed in other chemicals. Structural equation modeling revealed the contribution of microplastics in fish on the level of ECs contamination. The health quotient value indicated the low health risk of single compounds via fish consumption to humans; however, the combined risk of microplastics and ECs still needs to be considered. This work highlights the link between microplastics with associated ECs ingested by aquatic organisms and the human health risk of consuming polluted seafood.

Biotransformation of 6:2/4:2 fluorotelomer alcohols by Dietzia aurantiaca J3: Enzymes and proteomics

Per- and polyfluoroalkyl substances (PFAS) are recalcitrant synthetic organohalides known to negatively impact human health. Short-chain fluorotelomer alcohols are considered the precursor of various perfluorocarboxylic acids (PFCAs) in the environment. Their ongoing production and widespread detection motivate investigations of their biological transformation. Dietzia aurantiaca strain J3 was isolated from PFAS-contaminated landfill leachate using 6:2 fluorotelomer sulphonate (6:2 FTS) as a sulphur source. Resting cell experiments were used to test if strain J3 could transform fluorotelomer alcohols (6:2 and 4:2 FTOH). Strain J3 transformed fluorotelomer alcohols into PFCAs, polyfluorocarboxylic acids and transient intermediates. Over 6 days, 80 % and 58 % of 6:2 FTOH (0.1 mM) and 4:2 FTOH (0.12 mM) were degraded with 6.4 % and 14 % fluoride recovery respectively. Fluorotelomer unsaturated carboxylic acid (6:2 FTUCA) was the most abundant metabolite, accounting for 21 to 30 mol% of 6:2 FTOH (0.015 mM) applied on day zero. Glutathione (GSH) conjugates of 6:2/4:2 FTOH and 5:3 FTCA adducts were also structurally identified. Proteomics studies conducted to identify enzymes in the biotransformation pathway have revealed the role of various enzymes involved in β oxidation. This is the first report of 6:2/4:2 FTOH glutathione conjugates and 5:3 FTCA adducts in prokaryotes, and the first study to explore the biotransformation of 4:2 FTOH by pure bacterial strain.

Effect of Co-exposure to Additional Substances on the Bioconcentration of Per(poly)fluoroalkyl Substances: A Meta-Analysis Based on Hydroponic Experimental Evidence

A consensus has yet to emerge regarding the bioconcentration responses of per(poly)fluoroalkyl substances under co-exposure with other additional substances in aqueous environments. This study employed a meta-analysis to systematically investigate the aforementioned issues on the basis of 1,085 published datasets of indoor hydroponic simulation experiments. A hierarchical meta-analysis model with an embedded variance covariance matrix was constructed to eliminate the non-independence and shared controls of the data. Overall, the co-exposure resulted in a notable reduction in PFAS bioaccumulation (cumulative effect size, CES =  - 0.4287, p < 0.05) and bioconcentration factor (R2 = 0.9507, k < 1, b < 0) in hydroponics. In particular, the inhibition of PFAS bioconcentration induced by dissolved organic matter (percentage form of the effect size, ESP =  - 48.98%) was more pronounced than that induced by metal ions (ESP =  - 35.54%), particulate matter (ESP =  - 24.70%) and persistent organic pollutants (ESP =  - 18.66%). A lower AS concentration and a lower concentration ratio of ASs to PFASs significantly promote PFAS bioaccumulation (p < 0.05). The bioaccumulation of PFASs with long chains or high fluoride contents tended to be exacerbated in the presence of ASs. Furthermore, the effect on PFAS bioaccumulation was also significantly dependent on the duration of co-exposure (p < 0.05). The findings of this study provide novel insights into the fate and bioconcentration of PFAS in aquatic environments under co-exposure conditions.

Porphyrin metabolism and carbon fixation response of Skeletonema costatum at different growth phases to mixed emerging PFASs at environmental concentrations

Per- and polyfluoroalkyl substances (PFASs), especially as emerging compounds, have been widely detected in coastal seawater. However, the awareness of the interaction between PFASs at environmental concentrations and marine diatoms is still limited. In this study, Skeletonema costatum was exposed to three co-existing PFASs, namely hexafluoropropylene oxide dimer acid (HFPO-DA), 6 : 2 chlorinated polyfluorinated ether sulfonate (Cl-PFAES), and perfluoroethylcyclohexane sulfonate (PFECHS) (15-300 ng L-1 in total), for 14 days. In the 300 ng L-1 test group, the significant down-regulation of chlorophyllide a in porphyrin metabolism, light-harvesting capacity and carbon fixation were the main inhibitory mechanisms of photosynthesis by emerging PFASs at the 14th day compared to the 8th day, which indicated that they may have a shading effect on S. costatum. Additionally, mixed PFASs could also activate nicotinamide adenine dinucleotide phosphate (NADPH) oxidase by up-regulating gene gp91 and down-regulating genes CaM4 and NDPK2 to generate excessive ROS. This resulted in a decrease in the algal biomass, which would further weaken the primary productivity of S. costatum. Our findings illustrated that mixed emerging PFASs at environmental concentrations may interfere with the carbon balance of marine diatoms.

Concentration-dependent cellular responses of coontail (Ceratophyllum demersum) during the substitutions to perfluorooctanoic acid by its two alternatives

The substitutions of alternatives to legacy per- and polyfluoroalkyl substances (PFASs) may lead to unknown and variational joint toxicity on ecosystems. To comprehensively understand the effects of substitutions on aquatic ecosystems, the single and joint effects of perfluorooctanoic acid (PFOA) and its alternatives (perfluorobutanoic acid, PFBA; 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3,heptafluoropropoxy)propanoic acid, GenX) with various concentrations and compositions on a primary producer, coontail (Ceratophyllum demersum), were investigated at cellular level. Results showed that the substitutions of PFBA/GenX could alleviate the inhibition of PFOA on plant length, hydrogen peroxide accumulation, and chlorophyll b, due to the shifts of reactive oxygen species and their less toxicity to antioxidants. Significant up-regulations of superoxide dismutase, glutathione, and carotenoid implied their primary roles in defensing against PFASs (p < 0.05). Catalase/peroxidase was significantly up-regulated in PFBA/GenX substitutions (p < 0.05) to help alleviate stress. PFBA substitutions reduced 23.9 % of PFOA in organelle and GenX reduced the subcellular concentrations of PFOA by 1.8-17.4 %. Redundancy analysis suggested that PFOA, PFBA, and GenX in cell wall and organelle, as well as GenX in soluble fractions, were responsible for the cellular responses. These findings were helpful to understand the integrated effects on aquatic ecosystems during the substitutions to legacy PFASs by alternatives.

The Role of Mass Spectrometry in Protecting Public Health and the Environment from Synthetic Chemicals

Mass spectrometry (MS) has dramatically transformed environmental protection by facilitating the precise quantification and identification of pollutants. This review charts the evolution of environmental chemistry, intertwining it with advancements in analytical chemistry and MS technologies. It specifically focuses on the role of MS in studying persistent organic pollutants like organochlorine pesticides, polychlorinated biphenyls (PCBs), brominated fire retardants (BFRs), and perfluoroalkyl and polyfluoroalkyl substances (PFAS), marking significant milestones and their implications. Notably, the adoption of gas chromatography with MS in the 1970s and liquid chromatography with MS in the late 1990s profoundly expanded scientists' ability to detect complex pollutant mixtures. Over the past 50 years, the proliferation of potential pollutants has surged, necessitating more sophisticated analysis techniques, such as high-resolution mass spectrometry-nontargeted analysis (HRMS-NTA) and suspect screening. While HRMS promises to enhance the characterization of new environmental pollutants, a significant shift in chemical management strategies remains imperative. Despite technological advances, MS alone is insufficient to mitigate the risks from the continuous emergence of novel chemicals, with many potentially already present in the environment and bioaccumulating in humans.

Characterization of the Bioavailability of Per- and Polyfluoroalkyl Substances in Farmland Soils and the Factors Impacting Their Translocation to Edible Plant Tissues

In this study, various crops and farmland soils were collected from the Fen-Wei Plain, China, to investigate the bioavailability of perfluoroalkyl substances (PFAS), their accumulation in edible plant tissues, and the factors impacting their accumulation. PFAS were frequently detected in all of the crops, with total concentrations ranging from 0.61 to 35.8 ng/g. The results of sequential extractions with water, basic methanol, and acidic methanol indicate that water extraction enables to characterize the bioavailability of PFAS in soil to edible plant tissues more accurately, especially for the shorter-chain homologues. The bioavailability of PFAS was remarkably enhanced in the rhizosphere (RS) soil, with the strongest effect observed for leafy vegetables. The water-extracted Σ16PFAS in RS soil was strongly correlated with the content of dissolved organic carbon in the soil. Tannins and lignin, identified as the main components of plant root exudates by Fourier transform-ion cyclotron resonance mass spectrometry, were found to enhance the bioavailability of PFAS significantly. Redundancy analysis provided strong evidence that the lipid and protein contents in edible plant tissues play important roles in the accumulation of short- and long-chain PFAS, respectively. Additionally, the high water demand of these tissues during the growth stage greatly facilitated the translocation of PFAS, particularly for the short-chain homologues and perfluorooctanoic acid.

Impacts of rapidly urbanizing watershed comprehensive management on per- and polyfluoroalkyl substances pollution: Based on PFAS "diversity" assessment

The impact of watershed comprehensive management (WCM) on per- and polyfluoroalkyl substances (PFAS) pollution in rapidly urbanizing areas remains unclear. In a typical rapidly urbanizing watershed of Shenzhen, China, we investigated temporal variations in contamination level, primary source and ecological risk of 50 emerging and legacy PFAS, as well as the replacement trends of emerging PFAS before and after WCM during a six-year sampling campaign. We found that large-scale dredging was a non-negligible factor in abnormally increased PFAS concentrations (6.43 %-456.16 %) during WCM through their release from river sediments. To better characterize the diverse and complex PFAS contamination, a novel pollution assessment method, PFAS "diversity", was adopted based on a modified Shannon-Weiner diversity index and Pielou evenness index, reflecting numbers of PFAS detected and how evenly each PFAS contributed to the total PFAS concentrations at specific sampling sites. Importantly, we found that the Pielou evenness index can indicate and quantify abnormal pollution sources (especially point sources) along the river. The results revealed that WCM did not effectively reduce total PFAS concentrations and diversity in the rapidly urbanizing watershed but obviously improved point source pollution. Furthermore, 6:2 polyfluorinated phosphate diesters and hexafluoropropylene oxide dimer acid (GenX) that posed high ecological risks emerged and the number of sampling sites with high risk increased from 16 to 20 after WCM. Finally, we summarize several important issues related to PFAS contamination during WCM and propose specific countermeasures, such as adopting environmental dredging and reducing the proportion of ecological water replenished by wastewater treatment plant effluent for better control of PFAS pollution. Our study highlighted the limited effectiveness of WCM in mitigating PFAS pollution and the importance of emerging contaminant regulation in rapidly urbanizing watersheds during WCM.

Structural investigation of the complexation between vitamin B12 and per- and polyfluoroalkyl substances: Insights into degradation using density functional theory

Environmental remediation of per- and polyfluoroalkyl substances (PFAS) has become a significant research topic in recent years due to the fact that these materials are omnipresent, resistant to degradation and thus environmentally persistent. Unfortunately, they have also been shown to cause health concerns. PFAS are widely used in industrial applications and consumer products. Vitamin B12 (B12) has been identified as being catalytically active towards a variety of halogenated compounds such as PFAS. It has also been shown to be effective when using sulfide as a reducing agent for B12. This is promising as sulfide is readily available in the environment. However, there are many unknowns with respect to PFAS interactions with B12. These include the reaction mechanism and B12's specificity for PFAS with certain functionalization(s). In order to understand the specificity of B12 towards branched PFAS, we examined the atomistic interactions between B12 and eight different PFAS molecules using Density Functional Theory (B3LYP/cc-pVDZ). The PFAS test set included linear PFAS and their branched analogs, carboxylic acid and sulfonic acid headgroups, and aromatic and non-aromatic cyclic structures. Conformational analyses were carried out to determine the lowest energy configurations. This analysis showed that small chain PFAS such as perfluorobutanoic acid interact with the cobalt center of B12. Bulkier PFAS prefer to interact with the amine and carbonyl groups on the sidechains of the B12 ring system. Furthermore, computed complexation energies determined that, in general, branched PFAS (e.g. perfluoro-5-methylheptane sulfonic acid) interact more strongly than linear molecules (e.g. perfluorooctanesulfonic acid). Our results indicate that it may be possible to alter the interactions between B12 and PFAS by synthetically modifying the sidechains of the ring structure.

The investigation of the enrichment behavior of identified PFAS and unknown PFAA-precursors in water and suspended particulate matter of the surface microlayer: A case study in Tianjin (China)

The surface microlayer (SML) is an important air water interface layer, known as the skin of the ocean, which has chemical enrichment properties. Chemical enrichment in the SML can affect the occurrence of pollutants in the underlying water and air samples. Although the enrichment of per- and polyfluorinated substances (PFAS), a class of persistent organic pollutants of high concern, has been reported in the SML, information on the behavior of unknown PFAA-precursors in SML is lacked, and it is not clear whether there is a similar PFAS enrichment in suspended particulate matter (SPM) in the SML. Therefore, to investigate these questions, we conducted a systematic survey of 24 PFAS in 11 paired water and SPM samples from the SML and underlying water (U50cm and U2m) from the Duliujian River, which flows to the Bohai sea in Tianjin, China. The ∑PFAS mean concentrations in the water and SPM samples were 38.2 ng/L and 64.6 ng/g dw, respectively. The PFAS concentrations of PFAS in the SML were higher than those in the underlying water, and the enrichment factors (EFs) were greater in the SPM than that in the water. The long-chain PFAS EFs were greater than those for short-chain PFAS, indicating that the EFs were positively correlated with the hydrophobicity. Moreover, by applying the total oxidizable precursor (TOP) assay, the unknown PFAA-precursors (C5-C12) in the water and SPM contributed 11.4∼86.4 mol% and 7.1∼88.0 mol% to total PFAS, respectively. The ecological risk of the targeted PFAS in the SML was relatively higher than that in the underlying water, indicating that PFAS in the SML require more attention. Preliminary estimates indicate that the PFAS-enriched SML is an important exposure route that poses a potential risk to wildlife in rivers and oceans.

Novel Conductive and Redox-Active Molecularly Imprinted Polymer for Direct Quantification of Perfluorooctanoic Acid

This study developed a novel molecularly imprinted polymer (MIP) that is both conductive and redox-active for directly quantifying perfluorooctanoic acid (PFOA) electrochemically. We synthesized the monomer 3,4-ethylenedioxythiophene-2,2,6,6-tetramethylpiperidinyloxy (EDOT-TEMPO) for electropolymerization on a glassy carbon electrode using PFOA as a template, which was abbreviated as PEDOT-TEMPO-MIP. The redox-active MIP eliminated the need for external redox probes. When exposed to PFOA, both anodic and cathodic peaks of MIP showed a decreased current density. This observation can be explained by the formation of a charge-assisted hydrogen bond between the anionic PFOA and MIP's redox-active moieties (TEMPO) that hinder the conversion between the oxidized and reduced forms of TEMPO. The extent of the current density decrease showed excellent linearity with PFOA concentrations, with a method detection limit of 0.28 ng·L-1. PEDOT-TEMPO-MIP also exhibited high selectivity toward PFOA against other per- and polyfluoroalkyl substances (PFAS) at environmentally relevant concentrations. Our results suggest electropolymerization of MIPs was highly reproducible, with a relative standard deviation of 5.1% among three separate MIP electrodes. PEDOT-TEMPO-MIP can also be repeatedly used with good stability and reproducibility for PFOA detection. This study provides an innovative platform for rapid PFAS quantification using redox-active MIPs, laying the groundwork for developing compact PFAS sensors.

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.

Synergistic material-microbe interface toward deeper anaerobic defluorination

Per- and polyfluoroalkyl substances (PFAS), particularly the perfluorinated ones, are recalcitrant to biodegradation. By integrating an enrichment culture of reductive defluorination with biocompatible electrodes for the electrochemical process, a deeper defluorination of a C6-perfluorinated unsaturated PFAS was achieved compared to the biological or electrochemical system alone. Two synergies in the bioelectrochemical system were identified: i) The in-series microbial-electrochemical defluorination and ii) the electrochemically enabled microbial defluorination of intermediates. These synergies at the material-microbe interfaces surpassed the limitation of microbial defluorination and further turned the biotransformation end products into less fluorinated products, which could be less toxic and more biodegradable in the environment. This material-microbe hybrid system brings opportunities in the bioremediation of PFAS driven by renewable electricity and warrants future research on mechanistic understanding of defluorinating and electroactive microorganisms at the material-microbe interface for system optimizations.

Stereoselective Bioconcentration and Neurotoxicity of Perfluoroethylcyclohexane Sulfonate in Marine Medaka

Perfluoroethylcyclohexane sulfonate (PFECHS) is an emerging per- and polyfluoroalkyl substance used to replace perfluorooctane sulfonate (PFOS), mainly in aircraft hydraulic fluids. However, previous research indicates the potential neurotoxicity of this replacement chemical. In this study, marine medaka (Oryzias melastigma) was exposed to environmentally relevant concentrations of PFECHS (concentrations: 0, 0.08, 0.26, and 0.91 μg/L) from the embryonic stage for 90 days. After exposure, the brain and eyes of the medaka were collected to investigate the bioconcentration potential of PFECHS stereoisomers and their effects on the nervous systems. The determined bioconcentration factors (BCFs) of PFECHS ranged from 324 ± 97 to 435 ± 89 L/kg and from 454 ± 60 to 576 ± 86 L/kg in the brain and eyes of medaka, respectively. The BCFs of trans-PFECHS were higher than those of cis-PFECHS. PFECHS exposure significantly altered γ-aminobutyric acid (GABA) levels in the medaka brain and disrupted the GABAergic system, as revealed by proteomics, implying that PFECHS can disturb neural signal transduction like PFOS. PFECHS exposure resulted in significant alterations in multiple proteins associated with eye function in medaka. Abnormal locomotion was observed in PFECHS-exposed medaka larvae, which was rescued by adding exogenous GABA, suggesting the involvement of disrupted GABA signaling pathways in PFECHS neurotoxicity.

Roles of varying carbon chains and functional groups of legacy and emerging per-/polyfluoroalkyl substances in adsorption on metal-organic framework: Insights into mechanism and adsorption prediction

Metal-organic frameworks (MOFs) are promising adsorbents for legacy per-/polyfluoroalkyl substances (PFASs), but they are being replaced by emerging PFASs. The effects of varying carbon chains and functional groups of emerging PFASs on their adsorption behavior on MOFs require attention. This study systematically revealed the structure-adsorption relationships and interaction mechanisms of legacy and emerging PFASs on a typical MOF MIL-101(Cr). It also presented an approach reflecting the average electronegativity of PFAS moieties for adsorption prediction. We demonstrated that short-chain or sulfonate PFASs showed higher adsorption capacities (μmol/g) on MIL-101(Cr) than their long-chain or carboxylate counterparts, respectively. Compared with linear PFASs, their branched isomers were found to exhibit a higher adsorption potential on MIL-101(Cr). In addition, the introduction of ether bond into PFAS molecule (e.g., hexafluoropropylene oxide dimeric acid, GenX) increased the adsorption capacity, while the replacement of CF2 moieties in PFAS molecule with CH2 moieties (e.g., 6:2 fluorotelomer sulfonate, 6:2 FTS) caused a decrease in adsorption. Divalent ions (such as Ca2+ and SO42-) and solution pH have a greater effect on the adsorption of PFASs containing ether bonds or more CF2 moieties. PFAS adsorption on MIL-101(Cr) was governed by electrostatic interaction, complexation, hydrogen bonding, π-CF interaction, and π-anion interaction as well as steric effects, which were associated with the molecular electronegativity and chain length of each PFAS. The average electronegativity of individual moieties (named Me) for each PFAS was estimated and found to show a significantly positive correlation with the corresponding adsorption capacity on MIL-101(Cr). The removal rates of major PFASs in contaminated groundwater by MIL-101(Cr) were also correlated with the corresponding Me values. These findings will assist with the adsorption prediction for a wide range of PFASs and contribute to tailoring efficient MOF materials.

Defluorination of monofluorinated alkane by Rhodococcus sp. NJF-7 isolated from soil

Microbial degradation of fluorinated compounds raised significant attention because of their widespread distribution and potential environmental impacts. Here, we report a bacterial isolate, Rhodococcus sp. NJF-7 capable of defluorinating monofluorinated medium-chain length alkanes. This isolate consumed 2.29 ± 0.13 mmol L- 1 of 1-fluorodecane (FD) during a 52 h incubation period, resulting in a significant release of inorganic fluoride amounting to 2.16 ± 0.03 mmol L- 1. The defluorination process was strongly affected by the initial FD concentration and pH conditions, with lower pH increasing fluoride toxicity to bacterial cells and inhibiting enzymatic defluorination activity. Stoichiometric conversion of FD to fluoride was observed at neutral pH with resting cells, while defluorination was significantly lower at reduced pH (6.5). The discovery of the metabolites decanoic acid and methyl decanoate suggests that the initial attack by monooxygenases may be responsible for the biological defluorination of FD. The findings here provide new insights into microbial defluorination processes, specifically aiding in understanding the environmental fate of organic semi-fluorinated alkane chemicals.

Adsorption of per- and poly-fluoroalkyl substances (PFAS) on Ni: A DFT investigation

Electrocatalytic destruction of per- and polyfluoroalkyl substances (PFAS) is an emerging approach for treatment of PFAS-contaminated water. In this study, a systematic ab initio investigation of PFAS adsorption on Ni, a widely used electrocatalyst, was conducted by means of dispersion-corrected Density Functional Theory (DFT) calculations. The objective of this investigation was to elucidate the adsorption characteristics and charge transfer mechanisms of different PFAS molecules on Ni surfaces. PFAS adsorption on three of the most thermodynamically favorable Ni surface facets, namely (001), (110), and (111), was investigated. Additionally, the role of PFAS chain length and functional group was studied by comparing the adsorption characteristics of different PFAS compounds, namely perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorobutanesulfonic acid (PFBS), and perfluorobutanoic acid (PFBA). For each PFAS molecule-Ni surface facet pair, different adsorption configurations were considered. Further calculations were carried out to reveal the effect of solvation, pre-adsorbed atomic hydrogen (H), and surface defects on the adsorption energy. Overall, the results revealed that the adsorption of PFAS on Ni surfaces is energetically favorable, and that the adsorption is primarily driven by the functional groups. The presence of preadsorbed H and the inclusion of solvation produced less exothermic adsorption energies, while surface vacancy defects showed mixed effects on PFAS adsorption. Taken together, the results of this study suggest that Ni is a promising electrocatalyst for PFAS adsorption and destruction, and that proper control for the exposed facets and surface defects could enhance the adsorption stability.

Accumulation features and temporal trends (2002-2015) for legacy and emerging per- and polyfluoroalkyl substances (PFASs) in finless porpoises bycaught off Korean coasts

Legacy and emerging per- and polyfluoroalkyl substances (PFASs) were measured in livers of finless porpoises (Neophocaena asiaeorientalis; n = 167) collected in Korean waters from 2002 to 2015 to investigate their occurrence, bioaccumulation feature, temporal trends, and ecotoxicological implications. Perfulorooctane sulfonate (PFOS), perfluoroundecanoate (PFUnDA), and perfluorotridecanoate (PFTrDA) were the predominant PFASs found in the porpoises. The concentration of 6:2 chlorinated polyfluoroalkyl ether sulfonate (F-53B), an alternative to PFOS, was comparable to that of PFTrDA. Perfluorooctane sulfonamide (FOSA), a precursor of PFOS, was also detected in all the porpoises examined. All PFASs, including F-53B, accumulated to higher concentrations in immature porpoises compared with mature specimens, implying substantial maternal transfer and limited metabolizing capacity for PFASs. A significant correlation was observed between PFOS and F-53B concentrations, indicating similar bioaccumulation processes. Based on prenatal exposure and toxicity, F-53B is an emerging contaminant in marine ecosystems. Significantly increasing trends were observed in the concentrations of sulfonates, carboxylates, and F-53B between 2002/2003 and 2010, whereas the FOSA concentration significantly decreased. During 2010-2015, decreasing trends were observed in the concentrations of FOSA and sulfonates, whereas concentrations of carboxylate and F-53B increased without statistical significance, likely due to a gap for the implementation of regulatory actions between sulfonates and carboxylates. Although PFOS and PFOA were found to pose little health risk to porpoises, the combined toxicological effects of other contaminants should be considered to protect populations and to mitigate PFAS contamination in marine ecosystems.

Distinctive biotransformation and biodefluorination of 6:2 versus 5:3 fluorotelomer carboxylic acids by municipal activated sludge

Fluorotelomer carboxylic acids (FTCAs) represent an important group of per- and polyfluoroalkyl substances (PFAS) given their high toxicity, bioaccumulation potential, and frequent detection in landfill leachates and PFAS-impacted sites. In this study, we assessed the biodegradability of 6:2 FTCA and 5:3 FTCA by activated sludges from four municipal wastewater treatment plants (WWTPs) in the New York Metropolitan area. Coupling with 6:2 FTCA removal, significant fluoride release (0.56∼1.83 F-/molecule) was evident in sludge treatments during 7 days of incubation. Less-fluorinated transformation products (TPs) were formed, including 6:2 fluorotelomer unsaturated carboxylic acid (6:2 FTUCA), perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), and perfluorobutanoic acid (PFBA). In contrast, little fluoride (0.01∼0.09 F-/molecule) was detected in 5:3 FTCA-dosed microcosms, though 25∼68% of initially dosed 5:3 FTCA was biologically removed. This implies the dominance of "non-fluoride-releasing pathways" that may contribute to the formation of CoA adducts or other conjugates over 5:3 FTCA biotransformation. The discovery of defluorinated 5:3 FTUCA revealed the possibility of microbial attacks of the C-F bond at the γ carbon to initiate the transformation. Microbial community analysis revealed the possible involvement of 9 genera, such as Hyphomicrobium and Dechloromonas, in aerobic FTCA biotransformation. This study unraveled that biotransformation pathways of 6:2 and 5:3 FTCAs can be divergent, resulting in biodefluorination at distinctive degrees. Further research is underscored to uncover the nontarget TPs and investigate the involved biotransformation and biodefluorination mechanisms and molecular basis.

Investigating the effects of PFOA accumulation and depuration on specific phospholipids in zebrafish through imaging mass spectrometry

Perfluorooctanoic acid (PFOA) is an emerging persistent organic pollutant. Exposure to PFOA was observed to have a correlation with the expression levels of phospholipids. However, there are currently no studies that directly visualize the effects of PFOA on phospholipids. To this end, matrix-assisted laser desorption/ionization time of flight imaging mass spectrometry (MALDI-TOF-IMS) was used to visualize changes in phospholipids in the different tissues of zebrafish following exposure to PFOA. This study found that the major perturbed phospholipids were phosphatidylcholine (PC), diacylglycerol (DG), phosphatidic acid (PA), phosphatidylglycerol (PG), sphingomyelin (SM), and triacylglycerol (TG). These perturbed phospholipids caused by PFOA were reversible in some tissues (liver, gill, and brain) and irreversible in others (such as the highly exposed intestine). Moreover, the spatial distribution of perturbed phospholipids was mainly located around the edge or center of the tissues, implying that these tissue regions need special attention. This study provides novel insight into the biological toxicity and toxicity mechanisms induced by emerging environmental pollutants.

Transport and health risk of legacy and emerging per-and polyfluoroalkyl substances in the water cycle in an urban area, China: Polyfluoroalkyl phosphate esters are of concern

Polyfluoroalkyl phosphate esters (PAPs) are a group of emerging alternatives to the legacy per- and polyfluoroalkyl substances (PFAS). To better understand the transport and risk of PAPs in the water cycle, 21 PFAS including 4 PAPs and 17 perfluoroalkyl acids were investigated in multiple waterbodies in an urban area, China. PFAS concentrations ranged from 85.8 to 206 ng/L, among which PAPs concentrations ranged from 35.0 to 71.8 ng/L, in river and lake water with major substances of perfluorooctanoic acid (PFOA), 6:2 fluorotelomer phosphate (6:2 monoPAP), and 8:2 fluorotelomer phosphate (8:2 monoPAP). As transport pathways, municipal wastewater and precipitation were investigated for PFAS mass loading estimation, and PAPs transported via precipitation more than municipal wastewater discharge. Concentrations of PFAS in tap water and raw source water were compared, and PAPs cannot be removed by drinking water treatment. In tap water, PFAS concentrations ranged from 132 to 271 ng/L and among them PAPs concentrations ranged from 41.6 to 61.9 ng/L. Human exposure and health risk to PFAS via drinking water were assessed, and relatively stronger health risks were induced from PFOS, PAPs, and PFOA. The environmental contamination and health risk of PAPs are of concern, and management implications regarding their sources, exposure, and hazards were raised.

Hormetic effect of a short-chain PFBS on Microcystis aeruginosa and its molecular mechanism

Short-chain Perfluorinated compounds (PFCs), used as substitutes for highly toxic long-chain PFCs, are increasingly entering the aquatic environment. However, the toxicity of short-chain PFCs in the environment is still controversial. This study investigated the effects of short-chain perfluorobutanesulfonic acid (PFBS) at different concentrations (2.5, 6, 14.4, 36, and 90 mg/L) on M. aeruginosa growth under 12-day exposure and explored the molecular mechanism of toxicity using transcriptomics. The results showed that M. aeruginosa exhibited hormetic effects after exposure to PFBS. Low PFBS concentrations stimulated algal growth, whereas high PFBS concentrations inhibited it, and this inhibitory effect became progressively more pronounced with increasing PFBS exposure concentrations. Transcriptomics showed that PFBS promoted the pathways of photosynthesis, glycolysis, energy metabolism and peptidoglycan synthesis, providing the energy required for cell growth and maintaining cellular morphology. PFBS, on the other hand, caused growth inhibition in algae mainly through oxidative stress, streptomycin synthesis, and genetic damage. Our findings provide new insights into the toxicity and underlying mechanism of short-chain PFCs on algae and inform the understanding of the hormetic effect of short-chain PFCs, which are crucial for assessing their ecological risks in aquatic environments.

Prediction of critical micelle concentration for per- and polyfluoroalkyl substances

In this study, we focus on the development of Quantitative Structure-Property Relationship (QSPR) models to predict the critical micelle concentration (CMC) for per- and polyfluoroalkyl substances (PFASs). Experimental CMC values for both fluorinated and non-fluorinated compounds were meticulously compiled from existing literature sources. Our approach involved constructing two distinct types of models based on Support Vector Machine (SVM) algorithms applied to the dataset. Type (I) models were trained exclusively on CMC values for fluorinated compounds, while Type (II) models were developed utilizing the entire dataset, incorporating both fluorinated and non-fluorinated compounds. Comparative analyses were conducted against reference data, as well as between the two model types. Encouragingly, both types of models exhibited robust predictive capabilities and demonstrated high reliability. Subsequently, the model having the broadest applicability domain was selected to complement the existing experimental data, thereby enhancing our understanding of PFAS behaviour.

Fluorinated Propionic Acids Unmasked: Puzzling Fragmentation Phenomena of the Deprotonated Species

Environmental contamination by per- and polyfluorinated substances (PFAS) is an emerging concern for the public. In this study, short-chain PFAS such as deprotonated per- and polyfluorinated propionic acids are investigated using a combination of infrared multiple-photon dissociation (IRMPD) spectroscopy, collision-induced dissociation (CID), and density functional theory calculations. IRMPD and CID proceed via multiple competing pathways: (1) production of fluoroformate (FCO2-) and the associated ethylene derivative, (2) production of HF and the associated carbanion, or (3) loss of CO2 and the associated carbanion. Fluorinated propionic acids with at least one fluorine atom bound to the terminal carbon yield FCO2-, whereas loss of HF is observed in polyfluorinated species with at least one fluorine atom bound to the α-carbon. To explore the reaction pathways of the various fluorinated propionic acids, the nudged elastic band method is employed. The relative energy of the four-membered ring transition state leading to FCO2- dictates which product channel is observed in dissociation.

Per- and polyfluoroalkyl substances in waterbird feathers around Poyang Lake, China: Compound and species-specific bioaccumulation

As a nondestructive means of environmental monitoring, bird feathers have been used to analyze levels of per- and polyfluoroalkyl substances (PFASs) in specific environments. In this study, feather samples from 10 waterbird species around Poyang Lake were collected, and a pretreatment method for PFASs in feathers was optimized. The results showed that a combined cleaning method using ultrapure water and n-hexane effectively removed external PFASs. Twenty-three legacy and emerging PFASs were identified in the feathers of waterbirds, of which hexafluoropropylene oxides (HFPOs), chlorinated polyfluoroalkyl ether sulfonates (Cl-PFESAs), and sodium p-perfluorinated noneoxybenzene sulfonate (OBS) were reported for the first time, with their concentrations ranging from 0.060-2.4 ng·g-1 dw, 0.046-30 ng·g-1 dw, and lower than the method detection limit to 30 ng·g-1 dw, respectively. Compound- and species-specific bioaccumulation of PFASs was observed in the feathers of different waterbird species, suggesting that different PFAS types can be monitored through the selection of different species. Moreover, the concentrations of most PFCAs (except perfluorobutyric acid), perfluorooctane sulfonate (PFOS), and perfluorooctane sulfonamide (FOSA) were significantly positively correlated with δ15N (p < 0.05), while the concentrations of HFPOs, Cl-PFESAs, and OBS had significant positive correlations with δ13C. This indicates that the bioaccumulation of legacy and emerging PFASs in waterbird feathers is affected by their trophic level, feeding habits, and foraging area.

Progress in the application of ionic liquids and deep eutectic solvents for the separation and quantification of per- and polyfluoroalkyl substances

Per- and polyfluoroalkyl substances (PFASs), often labeled as "forever chemicals," earned this moniker due to their widespread presence in the environment, bioaccumulative tendencies, and resistance to remediation efforts. Employed for decades in various applications, spanning from stain-resistant fabrics to grease-proof food containers and fire-fighting foams, PFASs have evolved into an anthropogenic nightmare. Their adverse impact on human health, including immune dysfunction, infertility, and a spectrum of cancers, is alarming. Conventional water treatment methods, notably in the case of short-chain congeners, struggle to effectively eliminate PFASs, underscoring the pressing need for enhanced adsorbents. In recent years, there has been a prominent surge in the exploration of innovative techniques centered around ionic liquids (ILs) and deep eutectic solvents (DESs) for the removal of PFASs from various sources, including food samples like cooking oil, as well as environmental waters. In this Review, we delve into key advancements and discoveries related to the utilization of ILs and DESs as media for the liquid-liquid extraction of PFASs, as well as their applications as sorbents on solid-state or nanoscale supports. Our exploration encompasses groundbreaking approaches, including the utilization of dicationic ILs for ultra-sensitive mass spectrometric PFAS detection, alongside the innovative application of fluorinated ILs and hydrophobic DESs, enabling highly efficient PFAS sequestration. The landscape of existing PFAS extraction methods is riddled with formidable challenges, including limited selectivity, matrix interferences, subpar extraction efficiency, exorbitant costs, laborious procedures, ecological consequences, and a lack of standardization. Given these challenges, our review unequivocally asserts the pivotal role ILs and DESs will play in shaping the next generation of PFAS remediation strategies. Rigorous characterization of water solubility, toxicity, and biodegradation, along with improved recyclability and thorough techno-economic analyses, are essential for further progress. Future focus must also extend to addressing short-chain PFASs (such as PFBS) and PFAS alternatives (including ADONA, GenX, F-53B), which often pose higher toxicity risks than the compounds they aim to replace. A forward-thinking approach will integrate cutting-edge data-driven techniques, such as machine learning, to enhance our understanding and response to PFAS-related issues. Finally, we advocate seamless integration of PFAS separation with advanced treatment, efficiently isolating and destroying these compounds for a lasting solution to contamination challenges.

Tissue-specific distribution and bioaccumulation of perfluoroalkyl acids, isomers, alternatives, and precursors in citrus trees of contaminated fields: Implication for risk assessment

The ingestion of fruits containing perfluoroalkyl acids (PFAAs) presents potential hazards to human health. This study aimed to fill knowledge gaps concerning the tissue-specific distribution patterns and bioaccumulation behavior of PFAAs and their isomers, alternatives, and precursors (collectively as per-/polyfluoroalkyl substances, PFASs) within citrus trees growing in contaminated fields. It also assessed the potential contribution of precursor degradation to human exposure risk of PFASs. High concentrations of total target PFASs (∑PFASstarget, 92.45-7496.16 ng/g dw) and precursors measured through the total oxidizable precursor (TOP) assay (130.80-13979.21 ng/g dw) were found in citrus tree tissues, and short-chain PFASs constituted the primary components. The total PFASs concentrations followed the order of leaves > fruits > branches, bark > wood, and peel > pulp > seeds. The average contamination burden of peel (∑PFASstarget: 57.75%; precursors: 71.15%) was highest among fruit tissues. Bioaccumulation factors (BAFs) and translocation potentials of short-chain, branched, or carboxylate-based PFASs exceeded those of their relatively hydrophobic counterparts, while ether-based PFASs showed lower BAFs than similar PFAAs in above-ground tissues of citrus trees. In the risk assessment of residents consuming contaminated citruses, precursor degradation contributed approximately 36.07% to total PFASs exposure, and therefore should not be ignored.

Occurrence and distribution of steroid hormones (estrogen) and other contaminants of emerging concern in a south indian water body

Steroid hormones (SHs) are among the important classes of Contaminants of Emerging Concern (CECs) whose detection in aquatic environments is vital due to their potential adverse health impacts. Their detection is challenging because of their lower stability in natural conditions and low concentrations. This study reports the presence of steroid hormones in a major river system, the Periyar River, in Kerala (India). Water samples were collected from thirty different river locations in the case of SHs and five locations within these in the case of other CECs. These were subjected to LC-MS/MS and LC-Q-ToF/MS analyses. Five SHs, estriol, estrone, 17 β estradiol, progesterone, and hydroxy progesterone, were separated and targeted using MS techniques. The studies of the water samples confirmed the presence of the first three estrogens in different sampling sites, with estrone present in all the sampling sites. The concentration of estrone was detected in the range from 2 to 15 ng/L. Estriol and estradiol concentrations ranged from 1.0 to 5 ng/L and 1-6 ng/L, respectively. The hormones at some selected sites were continuously monitored for seven months. The chosen areas include the feed water sites for the drinking water treatment plants across the river. The monthly data revealed that estrone is the only SHs detected in all the samples in the selected months. The highest concentration of SH was found in August. Twelve CECs belonging to pharmaceuticals and personal care products were identified and quantified. In addition, 31 other CECs were also identified using non-target analysis. A detailed study of the hormone mapping reported here is the first from any South Indian River.

Unveiling nano-empowered catalytic mechanisms for PFAS sensing, removal and destruction in water

Per- and polyfluoroalkyl substances (PFAS) are organofluorine compounds used to manufacture various industrial and consumer goods. Due to their excellent physical and thermal stability ascribed to the strong CF bond, these are ubiquitously present globally and difficult to remediate. Extensive toxicological and epidemiological studies have confirmed these substances to cause adverse health effects. With the increasing literature on the environmental impact of PFAS, the regulations and research have also expanded. Researchers worldwide are working on the detection and remediation of PFAS. Many methods have been developed for their sensing, removal, and destruction. Amongst these methods, nanotechnology has emerged as a sustainable and affordable solution due to its tunable surface properties, high sorption capacities, and excellent reactivities. This review comprehensively discusses the recently developed nanoengineered materials used for detecting, sequestering, and destroying PFAS from aqueous matrices. Innovative designs of nanocomposites and their efficiency for the sensing, removal, and degradation of these persistent pollutants are reviewed, and key insights are analyzed. The mechanistic details and evidence available to support the cleavage of the CF bond during the treatment of PFAS in water are critically examined. Moreover, it highlights the challenges during PFAS quantification and analysis, including the analysis of intermediates in transitioning nanotechnologies from the laboratory to the field.

Legacy and alternative per-and polyfluoroalkyl substances (PFASs) in the Bohai Bay Rim: Occurrence, partitioning behavior, risk assessment, and emission scenario analysis

The use of alternative per- and polyfluoroalkyl substances (PFASs) has been practiced because of the restrictions on legacy PFASs. However, knowledge gaps exist on the ecological risks of alternatives and relationships between restrictions and emissions. This study systematically analyzed the occurrence characteristics, water-sediment partitioning behaviors, ecological risks, and emissions of legacy and alternative PFASs in the Bohai Bay Rim (BBR). The mean concentration of total PFASs was 46.105 ng/L in surface water and 6.125 ng/g dry weight (dw) in sediments. As an alternative for perfluorooctanoic acid (PFOA), hexafluoropropylene oxide dimer acid (GenX) had a concentration second only to PFOA in surface water. In sediments, perfluorobutyric acid (PFBA) and GenX were the two predominant contaminants. In the water-sediment partitioning system, GenX, 9-chlorohexadecafluoro-3-oxanone-1-sulfonic acid (F-53B), and 11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (8:2 Cl-PFESA) tended to be enriched towards sediments. The species sensitivity distribution (SSD) models revealed the low ecological risks of PFASs and their alternatives in the BBR. Moreover, predicted no-effected concentrations (PNECs) indicated that short-chain alternatives like PFBA and perfluorobutane sulfonate (PFBS) were safer for aquatic ecosystems, while caution should be exercised when using GenX and F-53B. Due to the incremental replacement of PFOA by GenX, cumulative emissions of 1317.96 kg PFOA and 667.22 kg GenX were estimated during 2004-2022, in which PFOA emissions were reduced by 59.2 % due to restrictions implemented since 2016. If more stringent restrictions are implemented from 2023 to 2030, PFOA emissions will further decrease by 85.0 %, but GenX emissions will increase by an additional 21.3 %. Simultaneously, GenX concentrations in surface water are forecasted to surge by 2.02 to 2.45 times in 2023. This study deepens the understanding of PFAS alternatives and assists authorities in developing policies to administer PFAS alternatives.

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

Due to increasing regulations on the production and consumption of legacy per- and polyfluoroalkyl substances (PFAS), the global use of PFAS substitutes increased tremendously, posing serious environmental risks owing to their bioaccumulation, toxicity, and lack of removal strategies. This review summarized the spatial distribution of alternative PFAS and their ecological risks in global freshwater and marine ecosystems. Further, toxicological effects of novel PFAS in various freshwater and marine species were highlighted. Moreover, degradation mechanisms for alternative PFAS removal from aquatic environments were compared and discussed. The spatial distribution showed that 6:2 chlorinated polyfluorinated ether sulfonate (6:2 CI-PFAES, also known as F-53B) was the most dominant emerging PFAS found in freshwater. Additionally, the highest levels of PFBS and PFBA were observed in marine waters (West Pacific Ocean). Moreover, short-chain PFAS exhibited higher concentrations than long-chain congeners. The ecological risk quotients (RQs) for phytoplankton were relatively higher >1 than invertebrates, indicating a higher risk for freshwater phytoplankton species. Similarly, in marine water, the majority of PFAS substitutes exhibited negligible risk for invertebrates and fish, and posed elevated risks for phytoplanktons. Reviewed studies showed that alternative PFAS undergo bioaccumulation and cause deleterious effects such as oxidative stress, hepatoxicity, neurotoxicity, histopathological alterations, behavioral and growth abnormalities, reproductive toxicity and metabolism defects in freshwater and marine species. Regarding PFAS treatment methods, photodegradation, photocatalysis, and adsorption showed promising degradation approaches with efficiencies as high as 90%. Finally, research gaps and future perspectives for alternative PFAS toxicological implications and their removal were offered.

Mollusc and crustacean consumption in the first 1000 days: a scoping review

Mollusc and crustacean consumption in the first 1000 d may improve maternal and child health by providing essential nutrients. However, in some contexts, molluscs and crustaceans have been associated with allergies and environmental contamination, potentially leading to adverse health and development outcomes. It is unclear whether the health benefits of consuming molluscs and crustaceans, collectively classified as shellfish in nutrition, are outweighed by the potential risks to pregnant women and children. We conducted a scoping review (PROSPERO: CRD42022320454) in PubMed, Scopus and EBSCO Global Health of articles published between January 2000 and March 2022 that assessed shellfish consumption during pregnancy, lactation or childhood (0-2 years) in relation to maternal health, child health or child development. A total of forty-six articles were included in this review. Overall, shellfish consumption was associated with higher biomarkers of environmental contaminants, with mercury being the most studied and having the strongest evidence base. The limited research on nutritional biomarker status shows an association between shellfish consumption and iodine status. Preterm birth was not associated with shellfish consumption, but newborn anthropometry showed mixed results, with several studies reporting lower birth weight with higher shellfish consumption. The few studies that examined child development and maternal health outcomes reported no significant associations. This review revealed trade-off health risks and benefits with inclusion of molluscs and crustaceans in the dietary patterns of mothers and young children. More research is needed to understand how these aquatic animal-source foods may be safely consumed and leveraged for improving human nutrition.

Efficient and fast remediation of soil contaminated by per- and polyfluoroalkyl substances (PFAS) by high-frequency heating

This study presents a novel thermal technology (high-frequency heating, HFH) for the decontamination of soil containing per- and polyfluoroalkyl substances (PFAS) and aqueous film-forming foams (AFFFs). Ultra-fast degradation of short-chain PFAS, long-chain homologs, precursors, legacy PFAS, emerging PFAS was achieved in a matter of minutes. The concentrations of PFAS and the soil type had a negligible impact on degradation efficiency, possibly due to the ultra-fast degradation rate overwhelming potential differences. Under the current HFH experiment setup, we achieved near-complete degradation (e.g., >99.9%) after 1 min for perfluoroalkyl carboxylic acids and perfluoroalkyl ether carboxylic acids and 2 min for perfluoroalkanesulfonic acids. Polyfluoroalkyl precursors in AFFFs were found to degrade completely within 1 min of HFH; no residual cationic, zwitterionic, anionic, or non-ionic intermediate products were detected following the treatment. The gaseous byproducts were considered. Most of gaseous organofluorine products of PFAS at low-and-moderate temperatures disappeared when temperatures reached 890 °C, which is in the temperature zone of HFH. For the first time, we demonstrated minimal loss of PFAS in water during the boiling process, indicating a low risk of PFAS entering the atmosphere with the water vapor. The findings highlight HFH its potential as a promising remediation tool for PFAS-contaminated soils.

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in water and edible fish species of Karun River, Ahvaz, Iran: spatial distribution, human health, and ecological risk assessment

Per- and polyfluoroalkyl substances (PFASs) such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are environmental contaminants with unfavorable impacts on human health and nature. This study aimed to determine the PFOA and PFOS concentration in water and fish samples from Karun, the largest river in Iran. According to the results, the PFOA and PFOS in water samples were 5.81-69.26 ng/L and not detected (n.d.)-35.12 ng/L, respectively. The dry season displayed higher concentrations in water samples than in the wet season. The maximum PFOS concentration measured was related to Barbus barbules sp. (27.89 ng/g). The human health risk assessment indicated minor risks (hazard ratio, HR < 1) from PFOA and PFOS through consuming contaminated drinking water and fish. Only HR value of PFOS in downstream area exceeded slightly 1.0, indicating potential health risk due to consumption of the river fish. Considering the average PFASs concentration, the risk quotients (RQs) showed low ecological risk.

Surface modifications of biopolymers for removal of per- and polyfluoroalkyl substances from water: Current research and perspectives

Per- and polyfluoroalkyl substances (PFAS) are highly recalcitrant organic contaminants that have attracted ever-increasing attention from the general public, government agencies and scientific communities. To remove PFAS from water, especially the enormous volume of drinking water, stormwater, and groundwater, sorption is the most practical approach. Success of this approach demands green, renewable, and sustainable materials for capturing PFAS at ng/L or µg/L levels. To meet this demand, this manuscript critically reviewed sorbents developed from biopolymers, such as chitosan (CTN), alginate (ALG), and cellulose (CEL) covering the period from 2008 to 2023. The use of different cross-linkers for the surface modifications of biopolymers were described. The underlying removal mechanism of biosorbents for PFAS adsorption from molecular perspectives was discussed. Besides reviewing and comparing the performance of different bio-based sorbents with respect to environmental factors like pH, and sorption kinetics and capacity, strategies for modifying biosorbents for better performance were proposed. Additionally, approaches for regeneration and reuse of the biosorbents were discussed. This was followed by further discussion of challenges facing the development of biosorbents for PFAS removal.

Deriving aquatic PNECs of endocrine disruption effects for PFOS and PFOA by combining species sensitivity weighted distributions and adverse outcome pathway networks

Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), as emerging endocrine-disrupting chemicals (EDCs), pose adverse effects on aquatic organisms. Conventional ecological risk assessment (ERA) not fully considering the mode of toxicity action of PFOS and PFOA, may result in an underestimation of risks and confuse decision-makers. In the study, we developed species sensitivity weighted distribution (SSWD) models based on adverse outcome pathway (AOP) networks for deriving predicted no-effect concentrations (PNECs). Three kinds of weighting criteria (intraspecies variation, trophic level abundance, and data quality) and weighted log-normal distribution methods were adopted. The developed models considered the inter/intraspecies variation and integrated nontraditional endpoints of endocrine-disrupting effects. The PNECs of endocrine disruption effects were derived as 2.52 μg/L (95% confidence intervals 0.667-9.85 μg/L) for PFOS and 18.7 μg/L (5.40-71.0 μg/L) for PFOA, which were more conservative than those derived from the SSD method and were comparable with the values in the literature based on the chronic toxicity data. For PFOS, the effect of growth and development was the most sensitive; however, for PFOA, the effect of reproduction was the most sensitive in the effects of growth and development, reproduction, biochemistry and genetics, and survival. The endocrine-disrupting effects of PFOS and PFOA are significant and need to be fully recognized in the ERA. This study provided an ERA framework that can improve the ecological relevance and reduce the uncertainty of PNECs of EDCs.

Molecular Cu Electrocatalyst Escalates Ambient Perfluorooctanoic Acid Degradation

Groundwater reservoirs contaminated with perfluoroalkyl and polyfluoroalkyl substances (PFASs) need purifying remedies. Perfluorooctanoic acid (PFOA) is the most abundant PFAS in drinking water. Although different degradation strategies for PFOA have been explored, none of them disintegrates the PFOA backbone rapidly under mild conditions. Herein, we report a molecular copper electrocatalyst that assists in the degradation of PFOA up to 93% with a 99% defluorination rate within 4 h of cathodic controlled-current electrolysis. The current-normalized pseudo-first-order rate constant has been estimated to be quite high for PFOA decomposition (3.32 L h-1 A-1), indicating its fast degradation at room temperature. Furthermore, comparatively, rapid decarboxylation over the first 2 h of electrolysis has been suggested to be the rate-determining step in PFOA degradation. The related Gibbs free energy of activation has been calculated as 22.6 kcal/mol based on the experimental data. In addition, we did not observe the formation of short-alkyl-chain PFASs as byproducts that are typically found in chain-shortening PFAS degradation routes. Instead, free fluoride (F-), trifluoroacetate (CF3COO-), trifluoromethane (CF3H), and tetrafluoromethane (CF4) were detected as fragmented PFOA products along with the evolution of CO2 using gas chromatography (GC), ion chromatography (IC), and gas chromatography-mass spectrometry (GC-MS) techniques, suggesting comprehensive cleavage of C-C bonds in PFOA. Hence, this study presents an effective method for the rapid degradation of PFOA into small ions/molecules.

An integrated assessment of ecological and human health risks of per- and polyfluoroalkyl substances through toxicity prediction approaches

Per- and polyfluoroalkyl substances (PFAS) are also known as "forever chemicals" due to their persistence and ubiquitous environmental distribution. This review aims to summarize the global PFAS distribution in surface water and identify its ecological and human risks through integrated assessment. Moreover, it provides a holistic insight into the studies highlighting the human biomonitoring and toxicological screening of PFAS in freshwater and marine species using quantitative structure-activity relationship (QSAR) based models. Literature showed that PFOA and PFOS were the most prevalent chemicals found in surface water. The highest PFAS levels were reported in the US, China, and Australia. The TEST model showed relatively low LC50 of PFDA and PFOS for Pimephales promelas (0.36 and 0.91 mg/L) and high bioaccumulation factors (518 and 921), revealing an elevated associated toxicity. The risk quotients (RQs) values for P. promelas and Daphnia magna were found to be 269 and 23.7 for PFOS. Studies confirmed that long-chain PFAS such as PFOS and PFOA undergo bioaccumulation in aquatic organisms and induce toxicological effects such as oxidative stress, transgenerational epigenetic effects, disturbed genetic and enzymatic responses, perturbed immune system, hepatotoxicity, neurobehavioral toxicity, altered genetic and enzymatic responses, and metabolism abnormalities. Human biomonitoring studies found the highest PFOS, PFOA, and PFHxS levels in urine, cerebrospinal fluid, and serum samples. Further, long-chain PFOA and PFOS exposure create severe health implications such as hyperuricemia, reduced birth weight, and immunotoxicity in humans. Molecular docking analysis revealed that short-chain PFBS (-11.84 Kcal/mol) and long-chain PFUnDA (-10.53 Kcal/mol) displayed the strongest binding interactions with human serum albumin protein. Lastly, research challenges and future perspectives for PFAS toxicological implications were also discussed, which helps to mitigate associated pollution and ecological risks.