An Overview of Per- and Polyfluoroalkyl Substances (PFAS) in the Environment: Source, Fate, Risk and Regulations

Passive biomonitoring for per- and polyfluoroalkyl substances using invasive clams, C. fluminea

Per- and polyfluoroalkyl substances (PFAS) are a class of toxic manufactured chemicals in commercial and consumer products. They are resistant to environmental degradation and mobile in soil, air, and water. This study used the introduced bivalve Corbicula fluminea as a passive biomonitor at sampling locations in a primary drinking water source in Virginia, USA. Many potential PFAS sources were identified in the region. Perfluorohexane sulfonate (PFHxS) and 6:2 fluorotelomer sulfonic acid (6:2 FTS) levels were highest downstream of an airport. The highest levels of short-chain carboxylic acids were in locations downstream of a wastewater treatment plant. Measured PFAS concentrations varied by location in C. fluminea, sediment, and surface water samples. Two compounds were detected across all three mediums. Calculated partitioning coefficients confirm bioaccumulation of PFAS in C. fluminea and sorption to sediment. C. fluminea bioaccumulated two PFAS not found in the other mediums. Perfluoroalkyl carboxylic acids and short-chain compounds dominated in clam tissue, which contrasts with findings of accumulation of longer-chain and perfluorosulfonic acids in fish. These findings suggest the potential for using bivalves to complement other organisms to better understand the bioaccumulation of PFAS and their fate and transport in a freshwater ecosystem.

Enhancing the Thermal Mineralization of Perfluorooctanesulfonate on Granular Activated Carbon Using Alkali and Alkaline-Earth Metal Additives

Thermal treatment has emerged as a promising approach for either the end-of-life treatment or regeneration of granular activated carbon (GAC) contaminated with per- and polyfluoroalkyl substances (PFAS). However, its effectiveness has been limited by the requirement for high temperatures, the generation of products of incomplete destruction, and the necessity to scrub HF in the flue gas. This study investigates the use of common alkali and alkaline-earth metal additives to enhance the mineralization of perfluorooctanesulfonate (PFOS) adsorbed onto GAC. When treated at 800 °C without an additive, only 49% of PFOS was mineralized to HF. All additives tested demonstrated improved mineralization, and Ca(OH)2 had the best performance, achieving a mineralization efficiency of 98% in air or N2. Its ability to increase the reaction rate and shift the byproduct selectivity suggests that its role may be catalytic. Moreover, additives reduced HF in the flue gas by instead reacting with the additive to form inorganic fluorine (e.g., CaF2) in the starting waste material. A hypothesized reaction mechanism is proposed that involves the electron transfer from O2- defect sites of CaO to intermediates formed during the thermal decomposition of PFOS. These findings advocate for the use of additives in the thermal treatment of GAC for disposal or reuse, with the potential to reduce operating costs and mitigate the environmental impact associated with incinerating PFAS-laden wastes.

Mechanochemical Synthesis of Cross-Linked Chitosan and Its Application as Adsorbent for Removal of Per- and Polyfluoroalkyl Substances from Simulated Electroplating Wastewater

Chitosan is a promising adsorbent for removing a wide range of pollutants from wastewater. However, its practical application is hindered by instability in acidic environments, which significantly impairs its adsorption capacity and limits its utilization in water purification. While cross-linking can enhance the acid stability of chitosan, current solvent-based methods are often costly and environmentally unfriendly. In this study, a solvent-free mechanochemical process was developed using high-energy ball milling to cross-link chitosan with various polyanionic linkers, including dextran sulfate (DS), poly[4-styrenesulfonic acid-co-maleic acid] (PSSM), and tripolyphosphate (TPP). The mechanochemically cross-linked (MCCL) chitosan products exhibited superior adsorption capacity and stability in acidic solutions compared to pristine chitosan. Chitosan cross-linked with DS (Cht-DS) showed the highest Reactive Red 2 (RR2) adsorption capacity, reaching 1559 mg·g-1 at pH 3, followed by Cht-PSSM (1352 mg·g-1) and Cht-TPP (1074 mg·g-1). The stability of MCCL chitosan was visually confirmed by the negligible mass loss of Cht-DS and Cht-PSSM tablets in pH 3 solution, unlike the complete dissolution of the pristine chitosan tablet. The MCCL significantly increased the microhardness of chitosan, with the order Cht-DS > Cht-PSSM > Cht-TPP, consistent with the RR2 adsorption capacity. When tested on simulated rinsing wastewater from chromium electroplating, Cht-DS effectively removed Cr(VI) (98.75% removal) and three per- and polyfluoroalkyl substances (87.40-95.87% removal), following pseudo-second-order adsorption kinetics. This study demonstrates the potential of the cost-effective and scalable MCCL approach to produce chitosan-based adsorbents with enhanced stability, mechanical strength, and adsorption performance for treating highly acidic industrial wastewater containing a mixture of toxic pollutants.

Non-Targeted PFAS Suspect Screening and Quantification of Drinking Water Samples Collected through Community Engaged Research in North Carolina's Cape Fear River Basin

A community engaged research (CER) approach was used to provide an exposure assessment of poly- and perfluorinated (PFAS) compounds in North Carolina residential drinking water. Working in concert with community partners, who acted as liaisons to local residents, samples were collected by North Carolina residents from three different locations along the Cape Fear River basin: upper, middle, and lower areas of the river. Residents collected either drinking water samples from their homes or recreational water samples from near their residence that were then submitted by the community partners for PFAS analysis. All samples were processed using weak anion exchange (WAX) solid phase extraction and analyzed using a non-targeted suspect screening approach as well as a quantitative approach that included a panel of 45 PFAS analytes, several of which are specific to chemical industries near the collection site locations. The non-targeted approach, which utilized a suspect screening list (obtained from EPA CompTox database) identified several PFAS compounds at a level two confidence rating (Schymanski scale); compounds identified included a fluorinated insecticide, a fluorinated herbicide, a PFAS used in polymer chemistry, and another that is used in battery production. Notably, at several locations, PFOA (39.8 ng/L) and PFOS (205.3 ng/L) were at levels that exceeded the mandatory EPA maximum contaminant level (MCL) of 4 ng/L. Additionally, several sites had detectable levels of PFAS that are unique to a local chemical manufacturer. These findings were communicated back to the community partners who then disseminated this information to the local residents to help empower and aid in making decisions for reducing their PFAS exposure.

Influence of soil composition and environmental factors on the adsorption of per- and polyfluoroalkyl substances: A review

Per- and polyfluoroalkyl substances (PFASs) have garnered considerable scientific and regulatory scrutiny due to their widespread distribution across environments and their potential toxicological impacts on human health. The pedosphere serves as a vital reservoir for these chemicals, significantly determining their environmental trajectory and chemical transformations. This study offers a comprehensive synthesis of the current understanding regarding the adsorption mechanics of PFASs in soil matrices. Due to their unique molecular structure, PFASs predominantly engage in hydrophobic and electrostatic interactions during soil adsorption. This work thoroughly evaluates the influence of various factors on adsorption efficiency, including soil properties, molecular characteristics of PFASs, and the prevailing environmental conditions. The complex nature of soil environments complicates isolating individual impacts on PFAS behavior, necessitating an integrated approach to understanding their environmental destinies better. Through this exploration, we seek to clarify the complex interplay of factors that modulate the adsorption of PFASs in soils, highlighting the urgent need for future research to disentangle the intricate and combined effects that control the environmental behavior of PFAS compounds.

PFAS in Nigeria: Identifying data gaps that hinder assessments of ecotoxicological and human health impacts

This review examines the extensive use and environmental consequences of Per- and Polyfluoroalkyl Substances (PFAS) on a global scale, specifically emphasizing their potential impact in Nigeria. Recognized for their resistance to water and oil, PFAS are under increased scrutiny for their persistent nature and possible ecotoxicological risks. Here, we consolidate existing knowledge on the ecological and human health effects of PFAS in Nigeria, focusing on their neurological effects and the risks they pose to immune system health. We seek to balance the advantages of PFAS with their potential ecological and health hazards, thereby enhancing understanding of PFAS management in Nigeria and advocating for more effective policy interventions and the creation of safer alternatives. The review concludes with several recommendations: strengthening regulatory frameworks, intensifying research into the ecological and health impacts of PFAS, developing new methodologies and longitudinal studies, fostering collaborative efforts for PFAS management, and promoting public awareness and education to support sustainable environmental practices and healthier communities in Nigeria.

New insights from an eight-year study on per- and polyfluoroalkyl substances in an urban terrestrial ecosystem

Per- and polyfluoroalkyl substances (PFAS) were analysed in a high number of terrestrial samples of soil, earthworm, bird eggs and liver from red fox and brown rat in an urban area in Norway from 2013 to 2020. PFOS and the long chain PFCAs were the most dominating compounds in all samples, proving their ubiquitous distribution. Other less studied compounds such as 6:2 FTS were first and foremost detected in earthworm. 8:2 FTS was found in many samples of fieldfare egg, sparrowhawk egg and earthworm, where the eggs had highest concentrations. Highest concentrations for both 6:2 FTS and 8:2 FTS were detected at present and former industry areas. FOSA was detected in many samples of the species with highest concentrations in red fox liver and brown rat liver of 3.3 and 5.5 ng/g ww. PFAS concentrations from the urban area were significantly higher than from background areas indicating that some of the species can be suitable as markers for PFAS emissions in an urban environment. Fieldfare eggs had surprisingly high concentrations of PFOS and PFCA concentrations from areas known to be or have been influenced by industry. Biota-soil-accumulation factor and magnification calculations indicate accumulation and magnification potential for several PFAS. Earthworm and fieldfare egg had average concentrations above the Canadian and European thresholds in diet for avian wildlife and predators. For earthworms, 18 % of the samples exceeded the European threshold (33 ng/g ww) of PFOS in prey for predators, and for fieldfare eggs, 35 % of the samples were above the same threshold. None of the soil samples exceeded a proposed PNEC of PFOS for soil living organisms of 373 ng/g dw.

Understanding PFAS toxicity through cell culture metabolomics: Current applications and future perspectives

Per- and polyfluoroalkyl substances (PFAS), ubiquitous environmental contaminants, pose significant challenges to ecosystems and human health. While cell cultures have emerged as new approach methodologies (NAMs) in ecotoxicity research, metabolomics is an emerging technique used to characterize the small-molecule metabolites present in cells and to understand their role in various biological processes. Integration of metabolomics with cell cultures, known as cell culture metabolomics, provides a novel and robust tool to unravel the complex molecular responses induced by PFAS exposure. In vitro testing also reduces reliance on animal testing, aligning with ethical and regulatory imperatives. The current review summarizes key findings from recent studies utilizing cell culture metabolomics to investigate PFAS toxicity, highlighting alterations in metabolic pathways, biomarker identification, and the potential linkages between metabolic perturbations. Additionally, the paper discusses different types of cell cultures and metabolomics methods used for studies of environmental contaminants and particularly PFAS. Future perspectives on the combination of metabolomics with other advanced technologies, such as single-cell metabolomics (SCM), imaging mass spectrometry (IMS), extracellular flux analysis (EFA), and multi-omics are also explored, which offers a holistic understanding of environmental contaminants. The synthesis of current knowledge and identification of research gaps provide a foundation for future investigations that aim to elucidate the complexities of PFAS-induced cellular responses and contribute to the development of effective strategies for mitigating their adverse effects on human health.

Occurrence, bioaccumulation and trophic dynamics of per- and polyfluoroalkyl substances in two tropical freshwater lakes

We have investigated the occurrence, distribution, and biomagnification of per- and polyfluoroalkyl substances (PFAS) in two tropical lakes (Asejire and Eleyele) of Southwestern Nigeria, with contrasting urban intensities. Over an 8-month period, we sampled sediment and fish species (Clarias gariepinus: CIG; Oreochromis niloticus: ON; Coptodon guineensis: CG; Sarotherodon melanotheron: SM) across trophic levels, and analyzed various PFAS congeners, in addition to a select group of toxicological responses. While herbivores (SM) and benthic omnivores (CIG) at Asejire exhibited elevated levels of PFBS and PFOS, the pelagic omnivores (ON) showed a dominance of PFOS, PFDA, PFHxDA and EtFOSE in the muscle. At the Eleyele urban lake, PFAS patterns was dominated by PFBS, EtFOSE, PFPeS, PFOcDA and PFOS in the herbivores (SM, CG), EtFOSE, PFOS and PFBS in the pelagic omnivore (ON) and benthic omnivore (ClG). The estimated biomagnification factor (BMF) analysis for both lakes indicated trophic level increase of PFOS, PFUnA and PFDA at the suburban lake, while PFOS and EtFOSE biomagnified at the urban lake. We detected the occurrence of diSAMPAP and 9CL-PF3ONS, novel compounds not commonly reported, in PFAS studies at both lakes. The studied toxicological responses varied across trophic groups in both lakes with probable modulations by environmental conditions, trophic structure, and relative PFAS exposures in the lakes. The present study documents, for the first time in Nigeria, or any other African country, the role of urbanization on contaminant load into the environment and their implications for contaminant dynamics within the ecosystem and for aquatic food safety.

Estimated scale of costs to remove PFAS from the environment at current emission rates

This discussion article builds upon existing data to ask whether environmental remediation and treatment is an economically viable solution to manage global environmental stocks of per- and polyfluoroalkyl substances (PFAS) without extensive use restrictions. Their environmental persistence means that PFAS released into the environment will remain there until actively removed and destroyed. Thus, removing and destroying PFAS from the global environment at the same rate they are currently being added reflects a theoretical steady-state condition where global PFAS stocks remain constant. Current costs to remove perfluoroalkyl acids (PFAAs), a subclass of PFAS, from the environment at the same rate they are being added were estimated here at 20 to 7000 trillion USD per year. If the ratio of total PFAS emissions to PFAAs emissions matches current production ratios, total PFAS release rates and associated treatment costs could be 10 to 10,000 higher than presented above for PFAAs only. Thus, current costs to remove and destroy the total PFAS mass released annually into the environment would likely exceed the global GDP of 106 trillion USD. While this level of treatment is not technically or economically achievable, it highlights the unaffordability of using environmental remediation alone to manage environmental PFAS stocks. Without significant reductions in production and emissions, the mass of PFAS present in the global environment will continue to rise. Treating targeted environmental media will be needed to manage human and environmental health impacts, but we are limited to the level of treatment that is practical and affordable.

Recent Progress of Solid-Liquid Interface-Mediated Contact-Electro-Catalysis

Contact electrification (CE) is a common physical process by which triboelectric charges are generated through the mutual contact between two objects. Despite the ongoing debates on CE's mechanism, recent advancements in technology have elucidated the primary role of electron transfer in most CE processes. This discovery leads to the spawning of an emerging field, known as contact-electro-catalysis (CEC), which utilizes the electron transfer phenomenon during CE to initiate CEC. In this work, we provide the first comprehensive review of the recent progress of the solid-liquid interface-mediated CEC process, including its working principles, relationship with surface science, recent breakthroughs in applications, and future challenges. We aim to provide fundamental guidance for researchers to understand the reaction mechanism of the CEC process and to propose potential pathways to enhance CEC efficiency from a surface and interfacial science perspective. Later, recent application scenarios using the novel CEC techniques are summarized, including wastewater treatment, efficient generation of hydrogen peroxide (H2O2), lithium-ion battery recycling, and CO2 reduction. In general, CEC technology has opened a new avenue for catalysis, effectively expanding the range of catalyst options and holding promise as a solution to a variety of complex catalytic challenges in the future.

Environmental pitfalls and associated human health risks and ecological impacts from landfill leachate contaminants: Current evidence, recommended interventions and future directions

The improper management of solid waste, particularly the dumping of untreated municipal solid waste, poses a growing global challenge in both developed and developing nations. The generation of leachate is one of the significant issues that arise from this practice, and it can have harmful impacts on both the environment and public health. This paper presents an overview of the primary waste types that generate landfill leachate and their characteristics. This includes examining the distribution of waste types in landfills globally and how they have changed over time, which can provide valuable insights into potential pollutants in a given area and their trends. With a lack of specific regulations and growing concerns regarding environmental and health impacts, the paper also focuses on emerging contaminants. Furthermore, the environmental and ecological impacts of leachate, along with associated health risks, are analyzed. The potential applications of landfill leachate, suggested interventions and future directions are also discussed in the manuscript. Finally, this work addresses future research directions in landfill leachate studies, with attention, for the first time to the potentialities that artificial intelligence can offer for landfill leachate management, studies, and applications.

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.

Interactions between MPs and PFASs in aquatic environments: A dual-character situation

Microplastics (MPs) and per- and polyfluoroalkyl substances (PFASs) have drawn great attention as emerging threats to aquatic ecosystems. Although the literature to study the MPs and PFASs alone has grown significantly, our knowledge of the overlap and interactions between the two contaminations is scarce due to the unawareness of it. Actually, numerous human activities can simultaneously release MPs and PFASs, and the co-sources of the two are common, meaning that they have a greater potential for interactions. The direct interaction lies in the PFASs adsorption by MPs in water with integrated mechanisms including electrostatic and hydrophobic interactions, plus many influence factors. In addition, the existence and transportation of MPs and PFASs in the aquatic environment have been identified. MPs and PFASs can be ingested by aquatic organisms and cause more serious combined toxicity than exposure alone. Finally, curbing strategies of MPs and PFASs are overviewed. Wastewater treatment plants (WWTPs) can be an effective place to remove MPs from wastewater, while they are also an important point source of MPs pollution in water bodies. Although adsorption has proven to be a successful curbing method for PFASs, more technological advancements are required for field application. It is expected that this review can help revealing the unheeded relationship and interaction between MPs and PFASs in aquatic environments, thus assisting the further investigations of both MPs and PFASs as a whole.

Per- and poly-fluoroalkyl substances removal in multi-barrier advanced water purification system for indirect potable reuse

The study evaluated the removal efficacy of per- and poly-fluoroalkyl substances (PFAS) across various advanced water treatment (AWT) processes in a field-scale AWT train using secondary effluent samples from a full-scale water reclamation facility (WRF). Samples collected from April to October 2020 revealed PFCAs as the dominant PFAS compounds in the WRF secondary effluent, with PFPeA having the highest average concentration and PFSAs in notably lower amounts. Temporal fluctuations in total PFAS concentrations peaked in September 2020, which may reflect the seasonality in PFAS discharges related to applications like AFFFs and pesticides. In assessing AWT processes, coagulation-flocculation-clarification-filtration system showed no notable PFAS reduction, while ozonation resulted in elevated PFBS and PFBA concentrations. Biological activated carbon (BAC) filtration effectively removed long-chain PFAS like PFOS and PFHxS but saw increased concentrations of short-chain PFAS post-treatment. Granular activated carbon (GAC) filtration was the most effective treatment, reducing all PFSAs below the detection limits and significantly decreasing most PFCAs, though short-chain PFCAs persisted. UV treatment did not remove short-chain PFCAs such as PFBA, PFPeA, and PFHxA. The findings highlight the efficacy of AWT processes like GAC in PFAS reduction for potable reuse, but also underscore the challenge presented by short-chain PFAS, emphasizing the need for tailored treatment strategies. PRACTITIONER POINTS: Secondary effluents showed higher concentrations of PFCAs compared to PFSAs. Advanced water treatment effectively removes long-chain PFAS but not short-chain. Ozonation may contribute to formation of short-chain PFAS. BAC is less effective on short-chain PFAS, requiring further GAC treatment.

PFAS: exploration of neurotoxicity and environmental impact

Per- and polyfluoroalkyl substances (PFAS) are widespread contaminants stemming from various industrial and consumer products, posing a grave threat to both human health and ecosystems. PFAS contamination arises from multiple sources, including industrial effluents, packaging, and product manufacturing, accumulating in plants and impacting the food chain. Elevated PFAS levels in water bodies pose significant risks to human consumption. This review focuses on PFAS-induced neurological effects, highlighting disrupted dopamine signalling and structural neuron changes in humans. Animal studies reveal apoptosis and hippocampus dysfunction, resulting in memory loss and spatial learning issues. The review introduces the BKMR model, a machine learning technique, to decipher intricate PFAS-neurotoxicity relationships. Epidemiological data underscores the vulnerability of young brains to PFAS exposure, necessitating further research. Stricter regulations, industry monitoring, and responsible waste management are crucial steps to reduce PFAS exposure.

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.

Fluoropolymers as Unique and Irreplaceable Materials: Challenges and Future Trends in These Specific Per or Poly-Fluoroalkyl Substances

In contrast to some low-molar-mass per- and polyfluoroalkyl substances (PFASs), which are well established to be toxic, persistent, bioaccumulative, and mobile, fluoropolymers (FPs) are water-insoluble, safe, bioinert, and durable. These niche high-performance polymers fulfil the 13 polymer-of-low-concern (PLC) criteria in their recommended conditions of use. In addition, more recent innovations (e.g., the use of non-fluorinated surfactants in aqueous radical (co)polymerization of fluoroalkenes) from industrial manufacturers of FPs are highlighted. This review also aims to show how these specialty polymers endowed with outstanding properties are essential (even irreplaceable, since hydrocarbon polymer alternatives used in similar conditions fail) for our daily life (electronics, energy, optics, internet of things, transportation, etc.) and constitute a special family separate from other "conventional" C1-C10 PFASs found everywhere on Earth and its oceans. Furthermore, some information reports on their recycling (e.g., the unzipping depolymerization of polytetrafluoroethylene, PTFE, into TFE), end-of-life FPs, and their risk assessment, circular economy, and regulations. Various studies are devoted to environments involving FPs, though they present a niche volume (with a yearly production of 330,300 t) compared to all plastics (with 460 million t). Complementary to other reviews on PFASs, which lack of such above data, this review presents both fundamental and applied strategies as evidenced by major FP producers.

Development of Poly(acrylamide)-Based Hydrogel Composites with Powdered Activated Carbon for Controlled Sorption of PFOA and PFOS in Aqueous Systems

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic compounds developed for various applications; some are connected to adverse health impacts including immunosuppression and higher susceptibility to some cancers. Current PFAS remediation treatments from aqueous sources include granular activated carbon (GAC) adsorption, membrane separation, and anion-exchange resin (AER) removal. Each has specific disadvantages, hence the need for a new and efficient technology. Herein, acrylamide-based hydrogel composites were synthesized with powdered activated carbon (PAC) and characterized to determine their affinity for PFAS. Physicochemical characterization included Fourier-Transform infrared spectroscopy (FTIR) to identify chemical composition, thermogravimetric analysis (TGA) to confirm PAC loading percentage, and aqueous swelling studies to measure the effect of crosslinking density. FTIR showed successful conversion of carbonyl and amine groups, and TGA analysis confirmed the presence of PAC within the network. Surface characterization also confirmed carbon-rich areas within composite networks, and the swelling ratio decreased with increasing crosslinking density. Finally, sorption of PFAS was detected via liquid chromatography with tandem mass spectrometry (LC-MS/MS), with removal efficiencies of up to 98% for perfluorooctanoic sulfonic acid (PFOS) and 96% for perfluorooctanoic acid (PFOA). The developed hydrogel composites exhibited great potential as advanced materials with tunable levers that can increase affinity towards specific compounds in water.

Adsorption of PFAS by All-Silica Zeolite β: Insights into the Effect of the Water Matrix, Regeneration of the Material, and Continuous PFAS Adsorption

Per- and polyfluoroalkyl substances (PFAS) are man-made organic compounds ubiquitously present in the environment. Due to their persistency and bioaccumulative nature, and because of increasingly stringent regulations of PFAS, their removal from the environment is necessary. Our initial study identified all-silica zeolite β as an alternative adsorbent with a high selectivity, affinity, and capacity for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) removal. Here, we study the influence of the PFAS chain length on the affinity and capacity of a novel material, all-silica zeolite β, showing that the *BEA zeolite is an ideal sorbent for the removal of PFAS with 8 carbons. The solution pH and the addition of cations or natural organic substances to the water matrix have minimal influence on PFOA/PFOS removal with the zeolite. Next, regeneration of a PFOS-loaded zeolite was assessed; besides thermal, solvent-driven regeneration of the zeolite is also possible, using well-selected combinations of non-noxious solvents. Lastly, continuous adsorption experiments show that zeolite can be used for larger-scale applications.

Comparative study of per- and polyfluoroalkyl substances (PFAS) removal from landfill leachate

Landfill leachate is one of the major point sources of per- and polyfluoroalkyl substances (PFAS) pollution. In this study, powdered activated carbon (PAC), granular activated carbon (GAC), anion exchange resin (AIX), nanofiltration (NF), ozonation, and foam fractionation were tested for treatment of the same leachate. These methods were compared in terms of PFAS removal efficiencies and treatment cost. More than 75% removal of long-chain PFAS (6-9 CF2) could be achieved with all the studied methods, though with high resource consumption. It was demonstrated that PFAS breakthrough was up to 27 times faster when the leachate was treated with GAC and AIX compared to groundwater treatment. Nanofiltration was the only method which could be practically applied for removal of PFAS with the shortest fluorinated carbon chain (3-4 CF2). Foam fractionation and AIX offered the most economical treatment, with an estimated cost of < 1 €/m3 for PFOS and PFOA reduction to ≥ 90%. The cost of treatment was shown to increase exponentially if the goal of > 60% ΣPFAS11 removal was applied. It was also discussed that composite parameters that include expected toxicity of different PFAS, such as ΣPFOAeq, should be used to obtain a cost-efficient reduction of PFAS-induced water toxicity.

Molecular detection of per- and polyfluoroalkyl substances in water using time-of-flight secondary ion mass spectrometry

Detection of per- and polyfluoroalkyl substances (PFASs) is crucial in environmental mitigation and remediation of these persistent pollutants. We demonstrate that time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a viable technique to analyze and identify these substances at parts per trillion (ppt) level in real field samples without complicated sample preparation due to its superior surface sensitivity. Several representative PFAS compounds, such as perfluorooctanesulfonic acid (PFOS), perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPeA), perfluoheptanoic acid (PFHpA), and perfluorononanoic acid (PFNA), and real-world groundwater samples collected from monitoring wells installed around at a municipal wastewater treatment plant located in Southern California were analyzed in this work. ToF-SIMS spectral comparison depicts sensitive identification of pseudo-molecular ions, characteristic of reference PFASs. Additionally, principal component analysis (PCA) shows clear discrimination among real samples and reference compounds. Our results show that characteristic molecular ion and fragments peaks can be used to identify PFASs. Furthermore, SIMS two-dimensional (2D) images directly exhibit the distribution of perfluorocarboxylic acid (PFCA) and PFOS in simulated mixtures and real wastewater samples. Such findings indicate that ToF-SIMS is useable to determine PFAS compounds in complex environmental water samples. In conclusion, ToF-SIMS provides simple sample preparation and high sensitivity in mass spectral imaging, offering an alternative solution for environmental forensic analysis of PFASs in wastewater in the future.

Impact of per- and polyfluorinated alkyl substances (PFAS) on the marine environment: Raising awareness, challenges, legislation, and mitigation approaches under the One Health concept

Per- and polyfluorinated alkyl substances (PFAS) have long been known for their detrimental effects on the ecosystems and living organisms; however the long-term impact on the marine environment is still insufficiently recognized. Based on PFAS persistence and bioaccumulation in the complex marine food network, adverse effects will be exacerbated by global processes such as climate change and synergies with other pollutants, like microplastics. The range of fluorochemicals currently included in the PFAS umbrella has significantly expanded due to the updated OECD definition, raising new concerns about their poorly understood dynamics and negative effects on the ocean wildlife and human health. Mitigation challenges and approaches, including biodegradation and currently studied materials for PFAS environmental removal are proposed here, highlighting the importance of ongoing monitoring and bridging research gaps. The PFAS EU regulations, good practices and legal frameworks are discussed, with emphasis on recommendations for improving marine ecosystem management.

The decomposition and emission factors of a wide range of PFAS in diverse, contaminated organic waste fractions undergoing dry pyrolysis

Current treatment options for organic waste contaminated with per- and polyfluoroalkyl substances (PFAS) are generally limited to incineration, composting or landfilling, all resulting in emissions. Dry pyrolysis is a promising emerging alternative to these practices, but there is uncertainty related to the fate of PFAS during this process. The present work first developed a robust method for the determination of PFAS in complex matrices, such as sewage sludge and biochar. Then, a mass balance was established for 56 different PFAS during full-scale pyrolysis (2-10 kg biochar hr^-1, 500-800 °C) of sewage sludges, food waste reject, garden waste and waste timber. PFAS were found in all wastes (56-3651 ng g^-1), but pyrolysis resulted in a ≥ 96.9% removal. Residual PFAS (0.1-3.4 ng g^-1) were detected in biochars obtained at temperatures up to 750 °C and were dominated by long chain PFAS. Emitted PFAS loads ranged from 0.01 to 3.1 mg tonne^-1 of biochar produced and were dominated by short chain PFAS. Emissions made up < 3% of total PFAS-mass in the wastes. Remaining uncertainties are mainly related to the presence of thermal degradation products in flue gas and condensation oils.

PFAS soil concentrations surrounding a hazardous waste incinerator in East Liverpool, Ohio, an environmental justice community

Per- and polyfluoroalkyl substances (PFAS) are a class of synthetic compounds widely used in industrial and consumer products. While PFAS provide product durability, these chemicals are ubiquitous, persistent, bioaccumulative, and toxic. These characteristics make the ultimate disposal of PFAS a challenge. One current disposal method is incineration; however, little research has been conducted on the safety and effectiveness of PFAS incineration. The characteristics of communities with hazardous waste incinerators that have received PFAS shipments indicate that more individuals with lower incomes and individuals with less education than the US average are at higher risk of exposure, which presents important environmental justice and health equity concerns of PFAS incineration. Situated in eastern Ohio, East Liverpool is an Appalachian community that is home to a large hazardous-waste incinerator, operated by Heritage WTI, that began accepting PFAS in 2019. Residents are concerned that the disposal lacks the research necessary to assure safety for the residents. Due to both community interest and data gaps regarding PFAS incineration, our research team conducted a pilot study to examine the distribution and concentration of PFAS in soil samples surrounding the incinerator. All 35 soil samples had measurable amounts of PFAS including perfluorobutanesulfonic acid (PFBS), perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and hexafluoropropylene oxide dimer acid (HFPO-DA)/GenX. PFOS was measured in the majority of soil samples (97%) with a range of 50-8,300 ng/kg. PFOA was measured in 94% of soil samples with a range of 51 ng/kg to 1300 ng/kg. HFPO-DA/GenX was measurable in 12 soil samples with concentrations of ranging from 150 ng/kg to 1500 ng/kg. Further research on PFAS disposal will advance knowledge and action related to regulatory requirements and exposure prevention, ultimately improving individual and community protections and health equity.

The unheeded inherent connections and overlap between microplastics and poly- and perfluoroalkyl substances: A comprehensive review

Microplastics (MPs) and poly- and perfluoroalkyl substances (PFASs) are receiving global attention due to their widespread presences and considerable level in the environment. Although the occurrence and fate of MPs and PFASs alone have been extensively studied, little was known about their unheeded connection and overlap between the two. Therefore, this review attempts to reveal it for the purpose of providing a new view from joint consideration of the two in the future studies. Initially, the critically examined data on the co-sources and existence of MPs and PFASs are summarized. Surprisingly, some products could be co-source of MPs and PFASs which are general in daily life while the distribution of the two is primary influenced by the human activity. Then, their interactions are reviewed based on the fact that PFASs can be sorbed onto MPs which are regarded as a vector of contaminations. The electrostatic interaction and hydrophobic contact are the predominant sorption mechanisms and could be influenced by environmental factors and properties of MPs and PFASs. The effects of MPs on the transport of PFASs in the environments, especially in aquatic environments are then discussed. Additionally, the current state of knowledge on the combined toxicity of MPs and PFASs are presented. Finally, the existing problems and future perspectives are outlined at the end of the review. This review provides an advanced understanding of the overlap, interaction and toxic effects of MPs and PFASs co-existing in the environment.

Poly- and Perfluoroalkyl Substances (PFAS): Do They Matter to Aquatic Ecosystems?

Poly- and perfluoroalkyl substances (PFASs) are a group of anthropogenic chemicals with an aliphatic fluorinated carbon chain. Due to their durability, bioaccumulation potential, and negative impacts on living organisms, these compounds have drawn lots of attention across the world. The negative impacts of PFASs on aquatic ecosystems are becoming a major concern due to their widespread use in increasing concentrations and constant leakage into the aquatic environment. Furthermore, by acting as agonists or antagonists, PFASs may alter the bioaccumulation and toxicity of certain substances. In many species, particularly aquatic organisms, PFASs can stay in the body and induce a variety of negative consequences, such as reproductive toxicity, oxidative stress, metabolic disruption, immunological toxicity, developmental toxicity, cellular damage and necrosis. PFAS bioaccumulation plays a significant role and has an impact on the composition of the intestinal microbiota, which is influenced by the kind of diet and is directly related to the host's well-being. PFASs also act as endocrine disruptor chemicals (EDCs) which can change the endocrine system and result in dysbiosis of gut microbes and other health repercussions. In silico investigation and analysis also shows that PFASs are incorporated into the maturing oocytes during vitellogenesis and are bound to vitellogenin and other yolk proteins. The present review reveals that aquatic species, especially fishes, are negatively affected by exposure to emerging PFASs. Additionally, the effects of PFAS pollution on aquatic ecosystems were investigated by evaluating a number of characteristics, including extracellular polymeric substances (EPSs) and chlorophyll content as well as the diversity of the microorganisms in the biofilms. Therefore, this review will provide crucial information on the possible adverse effects of PFASs on fish growth, reproduction, gut microbial dysbiosis, and its potential endocrine disruption. This information aims to help the researchers and academicians work and come up with possible remedial measures to protect aquatic ecosystems as future works need to be focus on techno-economic assessment, life cycle assessment, and multi criteria decision analysis systems that screen PFAS-containing samples. New innovative methods requires further development to reach detection at the permissible regulatory limits.

Microbial and thermal treatment techniques for degradation of PFAS in biosolids: A focus on degradation mechanisms and pathways

Per- and polyfluoroalkyl substances (PFAS) are persistent organic chemicals detected in biosolids worldwide, which have become a significant concern for biosolids applications due to their increasing environmental risks. Hence, it is pivotal to understand the magnitude of PFAS contamination in biosolids and implement effective technologies to reduce their contamination and prevent hazardous aftermaths. Thermal techniques such as pyrolysis, incineration and gasification, and biodegradation have been regarded as impactful solutions to degrade PFAS and transform biosolids into value-added products like biochar. These techniques can mineralize PFAS compounds under specific operating parameters, which can lead to unique degradation mechanisms and pathways. Understanding PFAS degradation mechanisms can pave the way to design the technology and to optimize the process conditions. Therefore, in this review, we aim to review and compare PFAS degradation mechanisms in thermal treatment like pyrolysis, incineration, gasification, smouldering combustion, hydrothermal liquefaction (HTL), and biodegradation. For instance, in biodegradation of perfluorooctane sulfonic acid (PFOS), firstly C-S bond cleavage occurs which is followed by hydroxylation, decarboxylation and defluorination reactions to form perfluoroheptanoic acid. In HTL, PFOS degradation is carried through OH^-catalyzed series of nucleophilic substitution and decarboxylation reactions. In contrast, thermal PFOS degradation involves a three-step random-chain scission pathway. The first step includes C-S bond cleavage, followed by defluorination of perfluoroalkyl radical, and radical chain propagation reactions. Finally, the termination of chain propagation reactions produces very short-fluorinated units. We also highlighted important policies and strategies employed worldwide to curb PFAS contamination in biosolids.

Immobilization of per- and polyfluoroalkyl substances (PFAS): Comparison of leaching behavior by three different leaching tests

The evaluation of PFAS immobilization performance in laboratory experiments, especially the long-term stability, is a challenge. To contribute to the development of adequate experimental procedures, the impact of experimental conditions on the leaching behavior was studied. Three experiments on different scales were compared: batch, saturated column, and variably saturated laboratory lysimeter experiments. The Infinite Sink (IS) test - a batch test with repeated sampling - was applied for PFAS for the first time. Soil from an agricultural field amended with paper-fiber biosolids polluted with various perfluoroalkyl acids (PFAAs; 655 μg/kg ∑¹⁸PFAAs) and polyfluorinated precursors (1.4 mg/kg ∑¹⁸precursors) was used as the primary material (N-1). Two types of PFAS immobilization agents were tested: treatment with activated carbon-based additives (soil mixtures: R-1 and R-2), and solidification with cement and bentonite (R-3). In all experiments, a chain-length dependent immobilization efficacy is observed. In R-3, the leaching of short-chain PFAAs was enhanced relative to N-1. In column and lysimeter experiments with R-1 and R-2, delayed breakthrough of short-chain PFAAs (C4) occurred (> 90 days; in column experiments at liquid-to-solid ratio (LS) > 30 L/kg) with similar temporal leaching rates suggesting that leaching in these cases was a kinetically controlled process. Observed differences between column and lysimeter experiments may be attributed to varying saturation conditions. In IS experiments, PFAS desorption from N-1, R-1, and R-2 is higher than in the column experiments (N-1: +44 %; R-1: +280 %; R-2: +162 %), desorption of short-chain PFAS occurred predominantly in the initial phase (< 14 days). Our findings demonstrate that sufficient operating times are essential in percolation experiments, e.g., in column experiments >100 days and LS > 30 L/kg. IS experiments may provide a faster estimate for nonpermanent immobilization. The comparison of experimental data from various experiments is beneficial to evaluate PFAS immobilization and to interpret leaching characteristics.

The universe of fluorinated polymers and polymeric substances and potential environmental impacts and concerns

Per- and polyfluoroalkyl substances (PFAS) are a diverse group of surface treatment chemicals falling under non-polymeric and polymeric categories. Polymeric PFAS are comprised of fluoropolymers, perfluoropolyethers and side-chain fluorinated polymers (SCFPs). Fluorinated polymers and polymeric substances have gained a significant market due to their chemical stability. To date, research and regulatory concern has primarily focused on the environmental occurrence and health effects of non-polymeric PFAS, particularly perfluoroalkyl acids and precursors. Industries consider most fluoropolymers as being "polymers of low concern", although there is already a considerable environmental burden and widespread contamination resulting from their production, manufacturing and use. For example, SCFPs are widely used, and known to release their perfluorinated side chains. Concerted action is needed to address the dearth of environment-associated information and understanding on polymeric PFAS.

Toxicity of per- and polyfluoroalkyl substances to microorganisms in confined hydrogel structures

Per- and polyfluoroalkyl substances (PFAS) as a group of environmentally persistent synthetic chemicals has been widely used in industrial and consumer products. Bioaccumulation studies have documented the adverse effects of PFAS in various living organisms. Despite the large number of studies, experimental approaches to evaluate the toxicity of PFAS on bacteria in a biofilm-like niche as structured microbial communities are sparse. This study suggests a facile approach to query the toxicity of PFOS and PFOA on bacteria (Escherichia coli K12 MG1655 strain) in a biofilm-like niche provided by hydrogel-based core-shell beads. Our study shows that E. coli MG1655 upon complete confinement in hydrogel beads exhibit altered physiological characteristics of viability, biomass, and protein expression, compared to their susceptible counterpart cultivated under planktonic conditions. We find that soft-hydrogel engineering platforms may provide a protective role for microorganisms from environmental contaminants, depending on the size or thickness of the protective/barrier layer. We expect our study to provide insights on the toxicity of environmental contaminants on organisms under encapsulated conditions that could potentially be useful for toxicity screening and in evaluating ecological risk of soil, plant, and mammalian microbiome.

Spatio-temporal trends in livestock exposure to per- and polyfluoroalkyl substances (PFAS) inform risk assessment and management measures

The migration of per- and polyfluoroalkyl substances (PFAS) onto agricultural properties has resulted in the accumulation of PFAS in livestock. The environmental determinants of PFAS accumulation in livestock from the grazing environment are poorly understood, resulting in limited capacity to manage livestock exposure and subsequent transfer of PFAS through the food chain. Analytical- (n = 978 samples of soil, water, pasture, and serum matrices), farm management/practice- and livestock physiology data were collated and interrogated from environmental PFAS investigations across ten farms, from four agro-ecological regions of Victoria (Australia). Statistical analysis identified perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) as key analytes of concern for livestock bioaccumulation. PFOS and PFHxS concentrations in livestock drinking water were positively correlated with serum concentrations while other intake pathways (pasture and soil) had weaker correlations. Seasonal trends in PFAS body burden (serum concentrations) were identified and suggested to be linked to seasonal grazing behaviours and physiological water requirements. The data showed for the first time that livestock exposure to PFAS is dynamic and with relatively short elimination half-lives, there is opportunity for exposure management. Meat from cattle, grazed on PFAS impacted sites, may exceed health-based guideline values for PFAS, especially for markets with low limits (like the European Commission Maximum Limits or EC MLs). This study found that sites with mean livestock drinking water concentrations as low as 0.003 μg PFOS/L may exceed the EC ML for PFOS in cattle meat. Risk assessment can be used to prioritise site cleanup and development of management plans to reduce PFAS body burden by considering timing of stock rotation and/or supplementation of primary exposure sources.

Water a major source of endocrine-disrupting chemicals: An overview on the occurrence, implications on human health and bioremediation strategies

Endocrine disrupting chemicals (EDCs) are toxic compounds that occur naturally or are the output of anthropogenic activities that negatively impact both humans and wildlife. A number of diseases are associated with these disruptors, including reproductive disorders, cardiovascular disorders, kidney disease, neurological disorders, autoimmune disorders, and cancer. Due to their integral role in pharmaceuticals and cosmetics, packaging companies, agro-industries, pesticides, and plasticizers, the scientific awareness on natural and artificial EDCs are increasing. As these xenobiotic compounds tend to bioaccumulate in body tissues and may also persist longer in the environment, the concentrations of these organic compounds may increase far from their original point of concentrations. Water remains as the major sources of how humans and animals are exposed to EDCs. However, these toxic compounds cannot be completely biodegraded nor bioremediated from the aqueous medium with conventional treatment strategies thereby requiring much more efficient strategies to combat EDC contamination. Recently, genetically engineered microorganism, genome editing, and the knowledge of protein and metabolic engineering has revolutionized the field of bioremediation thereby helping to breakdown EDCs effectively. This review shed lights on understanding the importance of aquatic mediums as a source of EDCs exposure. Furthermore, the review sheds light on the consequences of these EDCs on human health as well as highlights the importance of different remediation and bioremediation approaches. Particular attention is paid to the recent trends and perspectives in order to attain sustainable approaches to the bioremediation of EDCs. Additionally, rigorous restrictions to preclude the discharge of estrogenic chemicals into the environment should be followed in efforts to combat EDC pollution.

Occurrence of emerging contaminants in biosolids in northern Queensland, Australia

This study aims to identify and quantify different classes of emerging contaminants (ECs), such as pharmaceutical and personal care products (PPCPs), per-and polyfluoroalkyl substances (PFAS), heavy metals (HMs), polycyclic musks (PMs) in biosolids from different sewage treatment plants (STPs) from regional councils across Northern Queensland, Australia. Biosolids samples were named BS1 to BS7 for each council. The results revealed significant variations in the concentrations of different ECs in biosolids which could be explained in some instances by the characteristics of the upstream sewage network. For instance, BS4-biosolids from a small agricultural shire (largely sugarcane) showed the highest concentration of zinc and copper, which were 2430 and 1050 mg/kg, respectively. Among PPCPs, the concentration of ciprofloxacin was found to be the highest in BS3 and BS5, two large regional council areas which are a mix of domestic and industrial (predominantly domestic) biosolids of 1010 and 1590 ng/g, respectively. In addition, the quantity of sertraline was consistently high in all biosolids except from BS7, one of the smaller regional councils, which is indicative of the domestic catchments attached. PFAS compounds were detected in all biosolids samples except in BS6, one of the small (agricultural and tourist) catchments. Two PFAS compounds emerged as the most common pollutants that were perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). The largest industrial catchment biosolids, BS2 showed the highest concentration of PFOS at 253 ng/g, while the smallest regional council, BS7 showed the maximum concentration of 7.90 ng/g of PFOA. Overall, this study concludes that certain ECs such as HMs, antibiotics, PFOS and PFOA in biosolids may pose high environmental risks.

Estimating historical exposure to perfluoroalkyl acids in Security, Fountain, and Widefield Colorado: use of water-infrastructure blending and toxicokinetic models

Drinking water can be a major source of poly- and perfluoroalkyl substance (PFAS) exposure for humans. The lack of historic data on PFAS drinking-water concentrations and consumption patterns are a limiting factor for developing estimates of past exposure. Here, in contribution to a community-scale PFAS health effects study near fire training facilities that contaminated a local aquifer with PFASs, we present a novel water-infrastructure, mass-balance mixing model coupled to a non-steady state, single-compartment toxicokinetic model that used Monte Carlo simulations to estimate the start of PFAS exposure in drinking water for individuals within three PFAS-impacted communities in El Paso County, Colorado. Our modeling focused on perfluorohexane sulfonic acid (PFHxS) because median serum PFHxS concentrations in a sample of local residents (n = 213) were twelve times the median observed in the U.S. National Health and Nutrition Examination Survey (2015-2016). Modeling results for study participants were grouped according to their community of residence, revealing a median start of exposure for the town of Fountain of 1998 (25-75% interquartile range [IQR], 1992 to 2010), 2006 (IQR 1995 to 2012) for Security, and 2009 (IQR 1996-2012) for Widefield. Based on the towns' locations relative to an identified hydraulically upgradient PFAS source, the modeled exposure sequencing does not completely align with this conceptual flow model, implying the presence of an additional PFAS source for the groundwater between Widefield and Fountain.

Poly- and Perfluoroalkyl Substances Induce Immunotoxicity via the TLR Pathway in Zebrafish: Links to Carbon Chain Length

Previous studies have reported the immunotoxicity of per- and polyfluoroalkyl substances (PFASs), but it remains a significant challenge to assess over 10,000 distinct PFASs registered in the distributed structure-searchable toxicity (DSSTox) database. We aim to reveal the mechanisms of immunotoxicity of different PFASs and hypothesize that PFAS immunotoxicity is dependent on the carbon chain length. Perfluorobutanesulfonic acid (PFBA), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) representing different carbon chain lengths (4-9) at environmentally relevant levels strongly reduced the host's antibacterial ability during the zebrafish's early-life stage. Innate and adaptive immunities were both suppressed after PFAS exposures, exhibiting a significant induction of macrophages and neutrophils and expression of immune-related genes and indicators. Interestingly, the PFAS-induced immunotoxic responses were positively correlated to the carbon chain length. Moreover, PFASs activated downstream genes of the toll-like receptor (TLR), uncovering a seminal role of TLR in PFAS immunomodulatory effects. Myeloid differentiation factor 88 (MyD88) morpholino knock-down experiments and MyD88 inhibitors alleviated the immunotoxicity of PFASs. Overall, the comparative results demonstrate differences in the immunotoxic responses of PFASs due to carbon chain length in zebrafish, providing new insights into the prediction and classification of PFASs mode of toxic action based on carbon chain length.

Behavior of Per- and polyfluoroalkyl substances (PFAS) in Pilot-Scale vertical flow constructed wetlands treating landfill leachate

This study investigated the behavior of per- and polyfluoroalkyl substances (PFAS) in multiple pilot-scale vertical flow constructed wetlands (VFCW) treating landfill leachate. Eight pilot-scale VFCW columns planted with Typha latifolia or Scirpus Californicus were fed untreated municipal solid waste (MSW) landfill leachate that was diluted with potable water at a 1:10 ratio (1 part leachate to 10 parts total) at a fixed daily hydraulic loading rate of 0.525 m d^-1. Ninety-two PFAS were examined and 18 PFAS were detected at quantifiable concentrations (7 precursor species and 11 terminal species). The average concentration of Σ₉₂ PFAS in the influent was 3,100 ng L^-1, which corresponded with minimal reduction in the effluents from the four VFCW (decreases ranged from 1% to 12% on average for Σ₁₈ PFAS); however, precursors 6:3 FTCA, 7:3 FTCA, N-MeFOSAA, and N-EtFOSAA concentrations decreased significantly in the VFCW effluents, and significant decreases in the concentrations of these PFAA-precursors were concurrent with a significant increase in concentrations of five PFAAs (PFBA, PFNA, PFBS, PFOS, and PFOSI). This trend indicates that from a regulatory perspective, standalone VFCWs are likely to produce an apparent PFAS increase, which may also be true for many other leachate treatment processes incorporating aerobic biological treatment. Additional treatment to address PFAS should be integrated prior to the use of any system, including VFCWs, for the treatment of constituents of concern in MSW landfill leachate.

PFAS Contamination: Pathway from Communication to Behavioral Outcomes

ABSTRACTGuided by the risk information seeking and processing model, this study examines social cognitive variables that motivate individuals to actively seek and process information related to per- and polyfluoroalkyl substances (PFAS) contamination. Results indicate that information insufficiency, affective response, and informational subjective norms are positively related to information seeking and systematic processing, which are positively associated with policy support and intention to adopt risk mitigation behaviors. These findings suggest that when communicating the health risks of PFAS contamination to the general public, cognitive, affective, and normative factors are important initial steps to generate public interest in relevant information.

Sewage Water Treatment Using Chlorella Vulgaris Microalgae for Simultaneous Nutrient Separation and Biomass Production

Recovery of wastewater is essential for better management of water resources and can aid in reducing regional or seasonal water shortages. When algae were used to clean wastewater, amazing benefits were guaranteed, such as a decrease in the formation of dangerous solid sludge and the creation of valuable algal biomass through recycling of the nutrients in the wastewater. The trace elements nitrogen, phosphorus, and others that microalgae need for cell development are frequently present in contaminated wastewater. Hence, microalgal bioremediation is used in this study as an effective technique for the simultaneous treatment of COD, NH3-N, and orthophosphate from domestic wastewater and biomass production. Different concentrations of wastewaters were used. The maximum removals attained were: 84% of COD on the fifth day using the lowest mixing ratio of 50%, 95% of ammoniacal nitrogen, and 97% of phosphorus. The highest biomass production was achieved at day 12, except for the mixing ratio of 80% where the growth rate increased until day 14 at 400 mg/L.

Ultrastructural Alterations of the Glomerular Filtration Barrier in Fish Experimentally Exposed to Perfluorooctanoic Acid

Per- and polyfluoroalkyl substances can be referred to as the most critical group of contaminants of emerging concern. They can accumulate in high concentration in the kidney and are known to potentially affect its function. Nonetheless, there is a lack of knowledge about their morphopathological effect on the glomerular filtration barrier. Since previous research suggests perfluorooctanoic acid (PFOA) induces glomerular protein leakage, the glomerular filtration barrier of 30 carp from the same parental stock (10 unexposed; 10 exposed to 200 ng L^-1 of PFOA; and 10 exposed to 2 mg L^-1 of PFOA for 56 days) was screened for possible PFOA-induced ultrastructural lesions in order to shed light on the related pathophysiology. PFOA exposure affected the glomerular filtration barrier in carp experimentally exposed to 2 mg L^-1, showing ultrastructural alterations compatible with glomerulonephrosis: podocyte effacement, reduction of filtration slits and filtration slit diaphragms, basement membrane disarrangement, and occurrence of proteinaceous material in the urinary space. The results of the present research confirm the glomerular origin of the PFOA-induced protein leakage and can contribute to the mechanistic comprehension of PFOA's impact on renal function and to the assessment of the exposure effect of environmental pollutants on animals and humans, according to the One Health approach.

Phytoscreening for Per- and Polyfluoroalkyl Substances at a Contaminated Site in Germany

The aim of this study was to perform a phytoscreening of per- and polyfluoroalkyl substances (PFAS) at a contaminated site in Germany, to investigate the applicability of this technique for PFAS contaminations. Foliage of three species, namely, white willow (Salix alba L.), black poplar (Populus nigra L.), and black alder (Alnus glutinosa L.), were sampled to evaluate seasonal and annual variations in PFAS concentrations. The results of the phytoscreening clearly indicated species and specific differences, with the highest PFAS sum concentrations ∑₂₃ observed in October for white willow (0-1800 μg kg^-1), followed by black poplar (6.7-32 μg kg^-1) and black alder (0-13 μg kg^-1). The bulk substances in leaves were highly mobile short-chain perfluoroalkyl carboxylic acids (PFCAs). In contrast, the PFAS composition in soil was dominated by long-chain PFCAs, perfluorooctanoic acid (PFOA) and perfluorodecanoic acid (PFDA), as a result of the lower mobility with ∑₂₃PFAS ranging between 0.18 and 26 μg L^-1 (eluate) and between 66 and 420 μg kg^-1 (solid). However, the PFAS composition in groundwater was comparable to the spectrum observed in leaves. Spatial interpolations of PFAS in groundwater and foliage correspond well and demonstrate the successful application of phytoscreening to detect and delineate the impact of the studied PFAS on groundwater.

Per- and polyfluoroalkyl substances (PFAS) exposure through munitions in the Russia-Ukraine conflict

Considered contaminants of emerging concern, per- and polyfluoroalkyl substances (PFAS) are a class of toxic, manufactured chemicals found in commercial and consumer products such as nonstick cookware, food packaging, and firefighting foams. Human exposure to PFAS through inhalation and ingestion can cause a variety of harmful effects and negative health outcomes. Per- and polyfluoroalkyl substances possess high polarity and chemical stability, enabling them to resist degradation in most environmental conditions. These characteristics allow PFAS to be mobile in soil, air, and water, and bioaccumulate in living organisms. Due to their thermally resistant chemical properties, PFAS are used as binders in polymer-bonded explosives (PBX) and in various components of munitions. Thus, when munitions are detonated, PFAS are released into the environment as aerosols and can deposit in the soil, surface water, or biota. Air emission modeling suggests that ground-level and airborne detonation of munitions can increase PFAS deposition both locally and long range. Further, if industrial facilities with PFAS are damaged or destroyed, there is greater potential for environmental degradation from increased release of PFAS into the environment. As a consequence of their persistent nature, PFAS can remain in an environment long after armed conflict, indirectly affecting ecosystems, food sources, and human health. The toxic contamination from munitions could present a greater hazard to a larger population over time than acute detonation events. This article discusses methods for estimating war-related damage from PFAS by exploring predictive modeling approaches and postwar ground validation techniques. Integr Environ Assess Manag 2023;19:376-381. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Sorptive removal of per- and polyfluoroalkyl substances from aqueous solution: Enhanced sorption, challenges and perspectives

Per- and polyfluoroalkyl substances (PFASs) have garnered attention globally given their ubiquitous occurrence, toxicity, bioaccumulative potential, and environmental persistence. Sorption is widely used to remove PFASs given its simplicity and cost-effectiveness. This article reviews recently fabricated sorbents, including carbon materials, minerals, polymers, and composite materials. The characteristics and interactions of the sorbents with PFASs are discussed to better understand sorptive processes. Various sorbents have exhibited high removal rates for legacy perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). Novel polymers with special design better remove long- and short-chain PFASs than other sorbents. Although hydrophobic and electrostatic interactions mainly drive the sorption of anionic, cationic, and zwitterionic PFASs, enhancing PFAS sorption on designed sorbents has mainly depended on improving electrostatic interactions. Pearson correlation analysis showed that PFOS sorption capacity of sorbents is positively correlated with their specific surface area. Newly discovered pathways, including the air-water interfacial adsorption, F-F fluorophilic interactions, and (hemi) micelle formation, can enhance PFAS sorption to a certain extent. In addition to PFOA and PFOS, the sorption of emerging PFASs, including aqueous film-forming foam-relevant PFASs, constitutes a new research direction. The functionalization methods for enhancing PFAS sorption and challenges of PFAS sorption are also discussed to provide scope for future research. The discussions herein may contribute to developing efficient sorption technologies to remove PFASs.

Concentrations and distributions of fluorotelomer alcohols and perfluoroalkane sulfonamido substances in the atmosphere in the Pearl River Delta, China

Per and polyfluoroalkyl substances (PFASs) have attracted major global concerns because some of them are environmentally persistent, bioaccumulative, and toxic. Perfluoroalkyl acids (PFAAs) have been well-characterized in water, soil, and sediment; however, fluorotelomer alcohols and perfluoroalkane sulfonamido substances have been overlooked. In this study, concentrations of three fluorotelomer alcohols and four perfluoroalkane sulfonamido substances were determined in the air at nine locations representing urban, rural-urban transect, and urban areas in the Pearl River Delta region, China to investigate their seasonal and spatial distributions and potential sources. At least two of the targeted PFASs were detected in all air samples in the Pearl River Delta region, with concentrations ranging from 371 pg/sampler to 18700 pg/sampler. Fluorotelomer alcohols were dominant compounds (contributing 46% to the ∑₇PFAS concentration on average) in the atmosphere in the Pearl River Delta region. The total concentrations of the seven targeted PFASs were significantly higher in summer than in other seasons in urban areas. PFAS concentrations were positively related to the population density in the Pearl River Delta region. Local diffusive emission and long range transport could be sources of the seven PFASs in the air in the Pearl River Delta region.

Communicating Per- and Polyfluoroalkyl Substances (PFAS) Contamination to the Public Through Personal Relevance

It is important to understand people's risk perception to identify effective pathways for risk communication about per- and polyfluoroalkyl substances (PFAS) because they present emerging environmental health risks. Guided by dual-process theories of information processing, this study focuses on personal relevance as a key variable that influences risk perception, systematic processing, and information seeking intention. Through an experimental survey, we found that participants in the high personal relevance condition (n = 497) were more likely to process information systematically compared to those in the low personal relevance condition (n = 486). Results also revealed that personal relevance influenced systematic processing through risk judgment and emotional response. Message-specific systematic processing was positively associated with information seeking intention. Lastly, trust in government and trust in science had different relationships with systematic processing, demonstrating the importance of distinguishing different types of institutional trust in future research.

Per- and Poly-Fluoroalkyl Substances in Portuguese Rivers: Spatial-Temporal Monitoring

Eighteen per-and polyfluoroalkyl substances (PFASs) were investigated in surface waters of four river basins in Portugal (Ave, Leça, Antuã, and Cértima) during the dry and wet seasons. All sampling sites showed contamination in at least one of the seasons. In the dry season, perfluorooctanoate acid (PFOA) and perfluoro-octane sulfonate (PFOS), were the most frequent PFASs, while during the wet season these were PFOA and perfluobutane-sulfonic acid (PFBS). Compounds detected at higher concentrations were PFOS (22.6 ng L^-1) and perfluoro-butanoic acid (PFBA) (22.6 ng L^-1) in the dry and wet seasons, respectively. Moreover, the prospective environmental risks of PFASs, detected at higher concentrations, were evaluated based on the Risk Quotient (RQ) classification, which comprises acute and chronic toxicity. The results show that the RQ values of eight out of the nine PFASs were below 0.01, indicating low risk to organisms at different trophic levels in the four rivers in both seasons, wet and dry. Nevertheless, in the specific case of perfluoro-tetradecanoic acid (PFTeA), the RQ values calculated exceeded 1 for fish (96 h) and daphnids (48 h), indicating a high risk for these organisms. Furthermore, the RQ values were higher than 0.1, indicating a medium risk for fish, daphnids and green algae (96 h).

The role of PFAS in unsettling ocean carbon sequestration

Poly- and perfluoroalkyl substances (PFAS) and global climate change have attracted worldwide attention. PFAS have been found all across the planet, from the polar regions to the global ocean. Global oceans have emerged as a substantial sink for the carbon in the environment due to their remarkable capacity to absorb atmospheric carbon. Oceans absorb around 24% of the world's CO₂ emissions. Thus, the ocean plays a prominent role in the earth's carbon cycle. However, the widespread application of PFAS in a wide range of products and the inefficient management of PFAS-containing wastes made them ubiquitous pollutants, which are increasingly getting as a pollutant of emerging concern. Marine PFAS pollutants can produce harmful effects on gas exchange and the ocean's carbon cycle. Thus, it leads to an increase in greenhouse gas emissions, which eventually adversely affects global warming and climate change. Consequently, threats of marine PFAS to oceans carbon sequestration are discussed in this paper. Marine PFAS pollutants adversely affect the following sectors: (1) The growth and photosynthesis of phytoplankton, (2) development and reproduction of zooplankton by causing toxicity in zooplankton, (3) marine biological pomp, and (4) carbon stock of oceans. In this way, marine PFAS can pose a threat to ocean carbon sequestration. It is expected that this study can develop knowledge about the potential impact of PFAS on ocean carbon sequestration. However, the need for further research to investigate the hidden dimensions of this issue, including the potential scope and scale of this impact, should not be overlooked.

Spatial distribution, compositional profile, sources, ecological and human health risks of legacy and emerging per- and polyfluoroalkyl substances (PFASs) in freshwater reservoirs of Punjab, Pakistan

Per- and polyfluoroalkyl substances (PFASs) are a large group of chemicals reported in global environment and are responsible for various adverse impacts on humans and environment. We report a comprehensive study on occurrence of PFASs, including legacy, substitute and emerging ones, from Pakistan. Surface water samples were collected from five ecologically important freshwater reservoirs in Pakistan, namely, Head Panjnad (HP), Head Trimmu (HT), Chashma Barrage (CB), Head Blloki (HB), and Head Qadirabad (HQ). The detection frequencies of PFASs ranged between 37 %-100 %. The highest concentration of ∑₁₅PFASs was detected at HP (114.1 ng L^-1), whereas the lowest at HQ (19.9 ng L^-1). Among the analyzed PFASs, 6:2 fluorotelomer sulfonic acid (6:2 FTS) and perfluorooctanoic acid (PFOA) showed maximum mean concentrations of 9.1 ng L^-1 and 7 ng L^-1 at HP, followed by Perfluorooctane sulfonic acid (PFOS) with level of 0.99 ng L^-1 at HT. The ecological risk assessment for selected species i.e., daphnid, mysid, fish and green algae showed that PFOS, perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA) exhibited moderate risk i.e., Hazard Quotients (HQs) < 1 to the modeled organisms, whereas perfluorobutane sulfonic acid (PFBS) showed the high risk to green algae (HQs = 8.6) and PFOA presented a high risk to all the organisms (HQs ranged between 1.04 and 7.38). The level of ∑PFASs at HP (114.1 ng L^-1) exceed the EU guideline value of ∑PFASs in water (100 ng L^-1), however the risk quotient (RQ_mix) values of all age groups were < 1 implying that the detected PFASs in water do not pose risk to human health. Source apportionment through Positive Matrix Factorization (PMF) showed that industrial effluent is the main source of PFASs in freshwater reservoirs. Comparable concentrations of legacy and substitute PFASs in this study indicate that legacy PFASs are still in use adjacent to ecologically important water reservoirs.

Low-temperature persulfate activation by powdered activated carbon for simultaneous destruction of perfluorinated carboxylic acids and 1,4-dioxane

Carbonaceous materials have emerged as a method of persulfate activation for remediation. In this study, persulfate activation using powdered activated carbon (PAC) was demonstrated at temperatures relevant to groundwater (5-25 °C). At room temperature, increasing doses of PAC (1-20 g L^-1) led to increased persulfate activation (3.06 × 10^-6s^-1 to 2.10 × 10^-4 with 1 and 20 g L^-1 PAC). Activation slowed at lower temperatures (5 and 11 °C); however, substantial (>70 %) persulfate activation was achieved. PAC characterization showed that persulfate is activated at the surface of the PAC, as indicated by an increase in the PAC C:O ratio. Similarly, electron paramagnetic resonance (EPR) spectroscopy studies with a spin trapping agents (5,5-dimethyl-1-pyrroline N-oxide (DMPO)) and 2,2,6,6-tetramethylpiperidine (TEMP) revealed that singlet oxygen was not the main oxidizing species in the reaction. DMPO was oxidized to form 5,5-dimethylpyrrolidone-2(2)-oxyl-(1) (DMPOX), which forms in the presence of strong oxidizers, such as sulfate radicals. The persulfate/PAC system is demonstrated to simultaneously degrade both perfluorooctanoic acid (PFOA) and 1,4-dioxane at room temperature and 11 °C. With a 20 g L^-1 PAC and 75 mM persulfate, 80 % and 70 % of the PFOA and 1,4-dioxane, respectively, degraded within 6 h at room temperature. At 11 °C, the same PAC and persulfate doses led to 57% dioxane degradation and 54 % PFOA degradation within 6 h. Coupling PAC with persulfate offers an effective, low-cost treatment for simultaneous destruction of 1,4-dioxane and PFOA.