A Review of the Applications, Environmental Release, and Remediation Technologies of Per- and Polyfluoroalkyl Substances

Per- and polyfluoroalkyl substances (PFAS) and cancer: Detection methodologies, epidemiological insights, potential carcinogenic mechanisms, and future perspectives

Per- and polyfluoroalkyl substances (PFAS), known as "forever chemicals," are synthetic chemicals which have been used since the 1940s. Given their remarkable thermostability and chemical stability, PFAS have been widely utilized in commercial products, including textiles, surfactants, food packages, nonstick coatings, and fire-fighting foams. Thus, PFAS are widely distributed worldwide and have been detected in human urine, blood, breast milk, tissues and other substances. Growing concerns over the risks of PFAS, including their toxicity and carcinogenicity, have attracted people's attention. Recent reviews have predominantly emphasized advancements in the detection, adsorption, and degradation of PFAS through their chemical structures and toxic properties; however, further examination of the literature is needed to determine the link between PFAS exposure and cancer risk. Here, we introduced different PFAS detection methods based on sensors and liquid chromatography-mass spectrometry (LC-MS). Then, we discussed epidemiological investigations on PFAS levels and cancer risks in recent years, as well as the mechanisms underlying the carcinogenesis. Finally, we proposed the "4C principles" for ongoing exploration and refinement in this field. This review highlights PFAS-cancer associations to fill knowledge gaps and provide evidence-based strategies for future research.

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.

Emerging micropollutants - Environmental impact and source-controlled approaches: Current State and Future Prospects

Emerging micropollutants, originating from diverse sources, including pharmaceutical, pesticides, and industrial effluents, are a serious environmental concern. Their presence in natural water bodies has negative effects on ecosystems and human health. To address this issue, the importance of a source-controlled approach has grown, highlighting the use of advanced technologies such as oxidation processes, membrane filtration, and adsorption to prevent micropollutants from entering the environment. Therefore, this review provides a comprehensive overview of emerging micropollutants, their analytical detection methods, and their environmental impacts, with a focus on aquatic ecosystems, human health, and terrestrial environments. It also highlights the importance of using a source-controlled approach and provides insights into the benefits and drawbacks of this strategy. The primary micropollutants identified in this review were erythromycin, ibuprofen, and triclocarban, originating from the pharmaceutical industries for their use as antibiotics, analgesic, and antibacterial drugs. The primary analytical methods used for detection involved hybrid techniques that integrate chromatography with spectroscopy. Thus, this review emphasizes the source-controlled approach's benefits and drawbacks, focusing on emerging micropollutants, their detection, and impacts on ecosystems and health.

Synergistic impact of Fe-Zr in novel hybrid aminoclay catalytic TFC membrane for ultrafast emerging pollutant remediation

Finding new class of materials to overcome limitation in conventional membranes is a challenging task. Use of naturally stable and sustainable alternative materials stock is an emerging task. In this direction, a novel iron-zirconium hybrid aminoclay (FZ-AC) has emerged as a promising catalyst effectively employed to alleviate fouling concerns within the framework of a biopolymer-based thin film composite (TFC), constructed on a cellulose acetate (CA) support. Notably, FZ-AC exhibits remarkable catalytic activity in the degradation of foulants through potential free radicals generated from Fe and Zr active centres in synergy with oxidising agent. The optimised catalytic membrane (FZ-TFC-1) exhibited an ultrafast degradation of congo red (CR), eriochrome black-T (EBT), crystal violet (CV), methylene blue (MB), red-brown dye (RBn), bisphenol-A (BPA), azithromycin (AZC), and Cr(VI) within 4 min. The cooperative action of redox centres of Fe and Zr metal ions synergistically accelerated the swift production of reactive species and facilitated the efficient degradation of pollutants within a notably short timeframe. Furthermore, >95% of above dyes rejection was achieved with >67 L m-2.h-1 of flux. The results of a long-term study demonstrated that FZ-TFC membranes exhibit exceptional stability, retaining their performance for a duration up to 150 h. This extended period of stability underscores the superiority of these membranes over alternative counterparts, suggesting their robustness and reliability for sustained operation in various applications. This strategic utilization of FZ-AC representing a promising avenue for enhancing the efficacy and longevity of nanofiltration membranes, thereby advancing the frontier of membrane-based separation technologies.

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.

Per- and poly-fluoroalkyl substances (PFAS) sensing: A focus on representatively sampling soil vadose zones linked to nano-sensors

Per- and poly-fluoroalkyl substances (PFAS) are a group of organo-fluorine compounds that have been broadly used in consumer and industrial products spanning virtually all sectors. They can be found as surfactants, coatings and liners, polymer additives, fire retardants, adhesives, and many more. The chemical stability of the carbon fluorine bond and amphiphilic nature of PFAS result in their persistence and mobility in the environment via soil porewater, surface water and groundwater, with potential for adverse effects on the environment and human health. There is an emergent and increasing requirement for fast, low-cost, robust, and portable methods to detect PFAS, especially in the field. There may be thousands of PFAS compounds present in soil and water at extremely low concentration (0.01-250 ppb) that require measurement, and traditional technologies for continuous environmental sensing are challenged due to the complexity of soil chemistry. This paper presents a comprehensive review of potentially rapid PFAS measurement methods, focused on techniques for representative sampling of PFAS in porewater from contaminated soil, and approaches for pre-treatment of porewater samples to eliminate these interferences to be ready for PFAS-detecting sensors. The review discusses selectivity, a key factor underlying pre-treatment and sensing performance, and explores the interactions between PFAS and various sensors. PFAS chemical nano-sensors discussed are categorized in terms of the detection mechanism (electrochemical and optical). This review aims to provide guidance and outline the current challenges and implications for future routine PFAS sensing linked to soil porewater collection, to achieve more selective and effective PFAS sensors.

Association of per- and polyfluoroalkyl substances with the antioxidant bilirubin across pregnancy

BACKGROUND

In mechanistic and preliminary human studies, prenatal exposure to per- and polyfluoroalkyl substances (PFAS) is associated with oxidative stress, a potential contributor to maternal liver disease. Bilirubin is an endogenous antioxidant abundant in the liver that may serve as a physiological modulator of oxidative stress in pregnant people. Hence, our objective was to estimate the association between repeated measures of PFAS and bilirubin during pregnancy.

METHODS

The study population included 332 participants in the Atlanta African American Maternal-Child Cohort between 2014 and 2020. Serum samples were collected up to two times (early pregnancy: 6-18 gestational weeks; late pregnancy: 21-36 gestational weeks) for the measurement of perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and total bilirubin. We analyzed single PFAS with linear mixed effect regression and a mixture of the four PFAS with quantile g-computation. Models were repeated with a multiplicative interaction term to explore effect modification by study visit.

RESULTS

Overall, PFHxS was positively associated with bilirubin (β = 0.08, 95 % CI = 0.01, 0.15). We also found during late pregnancy, there was a positive association of PFHxS and the PFAS mixture with bilirubin (β = 0.12, 95 % CI = 0.02, 0.22; ψ = 0.19, 95 % CI = 0.03, 0.34, respectively). Finally, study visit modified the PFOA-bilirubin association (interaction p-value = 0.09), which was greater during early pregnancy (β = 0.08, 95 % CI = 0.01, 0.15).

CONCLUSION

In a prospective cohort of pregnant African Americans, an increase in PFOA, PFHxS, and the PFAS mixture was associated with an increase in bilirubin. Our results suggest that, depending on pregnancy stage, prenatal PFAS exposure disrupts the maternal liver antioxidant capacity.

Microfiltration Membrane Pore Functionalization with Primary and Quaternary Amines for PFAS Remediation: Capture, Regeneration, and Reuse

The widespread production and use of multi-fluorinated carbon-based substances for a variety of purposes has contributed to the contamination of the global water supply in recent decades. Conventional wastewater treatment can reduce contaminants to acceptable levels, but the concentrated retentate stream is still a burden to the environment. A selective anion-exchange membrane capable of capture and controlled release could further concentrate necessary contaminants, making their eventual degradation or long-term storage easier. To this end, commercial microfiltration membranes were modified using pore functionalization to incorporate an anion-exchange moiety within the membrane matrix. This functionalization was performed with primary and quaternary amine-containing polymer networks ranging from weak to strong basic residues. Membrane loading ranged from 0.22 to 0.85 mmol/g membrane and 0.97 to 3.4 mmol/g membrane for quaternary and primary functionalization, respectively. Modified membranes exhibited a range of water permeances within approximately 45-131 LMH/bar. The removal of PFASs from aqueous streams was analyzed for both "long-chain" and "short-chain" analytes, perfluorooctanoic acid and perfluorobutyric acid, respectively. Synthesized membranes demonstrated as high as 90% rejection of perfluorooctanoic acid and 50-80% rejection of perfluorobutyric acid after 30% permeate recovery. Regenerated membranes maintained the capture performance for three cycles of continuous operation. The efficiency of capture and reuse can be improved through the consideration of charge density, water flux, and influent contaminant concentration. This process is not limited by the substrate and, thus, is able to be implemented on other platforms. This research advances a versatile membrane platform for environmentally relevant applications that seek to help increase the global availability of safe drinking water.

Assessment of per- and poly-fluoroalkyl substances and physiological biomarkers in aquarium-based bottlenose dolphins and killer whales

Environmental concerns about per- and polyfluoroalkyl substances (PFAS) are considerably increasing due to their extensive use in commercial and consumer products. PFAS bioaccumulate and biomagnify throughout the food chain, and their toxicity and potential adverse health effects can potentially represent a threat to living organisms. In this study, we described PFAS profiles in the serum of two species of zoo-based bottlenose dolphins (Tursiops truncatus, n = 14 individuals) and killer whales (Orcinus orca, n = 14 individuals) from three locations (California, Florida, and Texas, USA), from 1994 to 2020. Potential physiological effects of PFAS were also explored by measuring different biomarkers (cortisol, corticosterone, aldosterone, TBARS, and hydrogen peroxide) while accounting for individual age, sex, and reproductive stage. All PFAS were detected in at least one of the individuals, considering both species. ΣPFAS reached 496 ng mL-1 in bottlenose dolphins and 230 ng mL-1 in killer whales. In both species, the PFAS with higher mean concentrations were PFOS (108.0-183.0 ng ml-1) and PFNA (14.40-85.50 ng ml-1), which are long-chain compounds. Newborn individuals of both species were also exposed to PFAS, indicating transference via placenta and lactation. Linear mixed model analyses indicated significant correlations between aldosterone, month, year, location, and status; and between hydrogen peroxide, month, year, age, status, ΣPFAS, and Σ short-chain PFAS in killer whales suggesting seasonal variations related to the animal's physiological state (e.g., reproductive cycles, stress responses, weaning events) and increased reactive oxygen species formation due to PFAS exposure. Given our results, other contaminant classes should be investigated in cetaceans as they might have additive and synergistic detrimental effects on these individuals. This study lays the foundation to guide future researchers and highlights the importance of such assessments for animal welfare, and species conservation. Our results may inform management decisions regarding regulations of contaminant thresholds in delphinids.

Emerging eco-friendly technologies for remediation of Per- and poly-fluoroalkyl substances (PFAS) in water and wastewater: A pathway to environmental sustainability

Per- and polyfluoroalkyl substances (PFAS) are rampant, toxic contaminants from anthropogenic sources, called forever chemicals for their recalcitrance. Although banned in several parts of the world for public health implications, including liver, kidney, and testicular diseases, PFAS are abundant in water sources due to easy dispersion. With chemical properties resulting from strong hydrophobic bonds, they defile many physicochemical removal methods. Though adsorption processes such as granular activated carbon (GAC) are widely used, they are marred by several limitations, including cost and secondary contamination. Thus, eco-friendly methods involving a synergy of the removal principles have been preferred for ease of use, cost-effectiveness, and near-zero effect on the environment. We present novel eco-friendly methods as the solution to PFAS remediation towards environmental sustainability. Current eco-friendly methods of PFAS removal from water sources, including electrocoagulation, membrane/filtration, adsorption, and phytoremediation methods, were highlighted, although with limitations. Novel eco-friendly methods such as microbial fuel cells, photoelectrical cells, and plasma treatment offer solutions to PFAS remediation and are quite efficient in terms of cost, result, and environmental sustainability. Overall, the successful integration of eco-friendly techniques in a seamless manner ensures the desired result. We also present a balanced position on the ecosystem impact of these ecofriendly methods, noting the successes towards environmental sustainability while exposing the gaps for further research.

Effect of electrolyte composition on electrocatalytic transformation of perfluorooctanoic acid (PFOA) in high pH medium

Recent regulatory actions aim to limit per- and polyfluoroalkyl substances (PFAS) concentrations in drinking water and wastewaters. Regenerable anion exchange resin (AER) is an effective separation process to remove PFAS from water but will require PFAS post-treatment of the regeneration wastestream. Electrocatalytic (EC) processes using chemically boron-doped diamond electrodes, stable in a wide range of chemical compositions show potential to defluorinate PFOA in drinking water and wastewater treatments. Chemical composition and concentration of mineral salts in supporting electrolytes affect AER regeneration efficiency, and play a crucial role in the EC processes. Their impact on PFAS degradation remains understudied. This study investigates the impact of 17 brine electrolytes with different compositions on perfluorooctanoic acid (PFOA) degradation in an alkaline medium and explores the correlation between the rate of PFOA degradation and the solution's conductivity. Results show that higher electrolyte concentrations and conductivity lead to faster PFOA degradation rates. The presence of chloride anions have negligible impact on the degradation rate. However, the presence of nitrate salts reduce PFOA degradation efficiency. Additionally, the use of mixed electrolytes may be a promising approach for reducing the cost of EC operations. PFOA degradation was not influenced by the pH of the bulk solution.

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.

Adsorption Technology for PFAS Removal in Water: Comparison between Novel Carbonaceous Materials

PFASs are a variety of ecologically persistent compounds of anthropogenic origin loosely included in many industrial products. In these, the carbon chain can be fully (perfluoroalkyl substances) or partially (polyfluoroalkyl substances) fluorinated. Their ubiquitous presence in many environmental compartments over the years and their long-lasting nature have given rise to concerns about the possible adverse effects of PFASs on ecosystems and human health. Among a number of remediation technologies, adsorption has been demonstrated to be a manageable and cost-effective method for the removal of PFASs in aqueous media. This study tested two novel and eco-friendly adsorbents (pinewood and date seeds biochar) on six different PFASs (PFOS, GenX, PFHxA, PFOA, PFDA, and PFTeDA). Batch sorption tests (24 h) were carried out to evaluate the removal efficiency of each PFAS substance in relation to the two biochars. All samples of liquid phase were analyzed by a developed and then a well-established method: (i) pre-treatment (centrifugation and filtration) and (ii) determination by high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS/MS). The results evidenced a comparable adsorption capacity in both materials but greater in the long-chain PFASs. Such findings may lead to a promising path towards the use of waste-origin materials in the PFAS remediation field.

The bioaccumulation and ecotoxicity of co-exposure of per(poly)fluoroalkyl substances and polystyrene microplastics to Eichhornia crassipes

Gen X and F-53B have been popularized as alternatives to PFOA and PFOS, respectively. These per(poly)fluoroalkyl substances pervasively coexist with microplastics (MPs) in aquatic environments. However, there are knowledge gaps regarding their potential eco-environmental risks. In this study, a typical free-floating macrophyte, Eichhornia crassipes (E. crassipes), was selected for hydroponic simulation of a single exposure to PFOA, PFOS, Gen X, and F-53B, and co-exposure with polystyrene (PS) microspheres. F-53B exhibited the highest bioaccumulation followed by Gen X, PFOA, and PFOS. In the presence of PS MPs, the bioavailabilities of the four PFASs shifted and the whole plant bioconcentration factors improved. All four PFASs induced severe lipid peroxidation, which was exacerbated by PS MPs. The highest integrated biomarker response (IBR) was observed for E. crassipes (IBR of shoot: 30.01, IBR of root: 22.79, and IBR of whole plant: 34.96) co-exposed to PS MPs and F-53B. The effect addition index (EAI) model revealed that PS MPs showed antagonistic toxicity with PFOA and PFOS (EAI < 0) and synergistic toxicity with Gen X and F-53B (EAI > 0). These results are helpful to compare the eco-environmental impacts of legacy and alternative PFASs for renewal process of PFAS consumption and provide toxicological, botanical, and ecoengineering insights under co-contamination with MPs.

PFOA-contaminated soil remediation: a comprehensive review

Soil and groundwater contamination has been raised as a concern due to the capability of posing a risk to human health and ecology, especially in facing highly toxic and emerging pollutants. Because of the prevalent usage of perfluorooctanoic acid (PFOA), in industrial and production processes, and subsequently the extent of sites contaminated with these pollutants, cleaning up PFOA polluted sites is paramount. This research provides a review of remediation approaches that have been used, and nine remediation techniques were reviewed under physical, chemical, and biological approaches categorization. As the pollutant specifications, environmental implications, and adverse ecological effects of remediation procedures should be considered in the analysis and evaluation of remediation approaches, unlike previous research that considered a couple of PFAS pollutants and generally dealt with technical issues, in this study, the benefits, drawbacks, and possible environmental and ecological adverse effects of PFOA-contaminated site remediation also were discussed. In the end, in addition to providing sufficient and applicable understanding by comprehensively considering all aspects and field-scale challenges and obstacles, knowledge gaps have been found and discussed.

Impact of perfluorooctanoic acid (PFOA) and perfluorobutanoic acid (PFBA) on oxidative stress and metabolic biomarkers in human neuronal cells (SH-SY5Y)

Perfluorinated alkyl substances (PFAS) are pervasive environmental contaminants that have attracted considerable attention due to their widespread utilization, resilient characteristics, adverse health implications, and regulatory scrutiny. Despite documented toxicity in living organisms, the precise molecular mechanisms governing the induced adverse effects remain unclear. This study aims to elucidate mechanisms of toxic action by collecting empirical data sets along oxidative stress and metabolic disruption pathways. We investigated the impact of long-chain PFAS (perfluorooctanoic acid (PFOA)) and its short-chain analog (perfluorobutanoic acid (PFBA)) on human neuronal cells (SH-SY5Y). The functionalities of enzymes associated with oxidative stress (catalase and glutathione reductase) and cellular metabolism (lactate dehydrogenase and pyruvate dehydrogenase) were also characterized. Our results reveal that a 24-hour exposure to PFOA and PFBA generated significant levels of reactive oxygen species. Correspondingly, there was a notable decline in catalase and glutathione reductase activities, with PFBA demonstrating a more pronounced effect. High concentrations of PFOA and PFBA reduced metabolic activity. Lactate dehydrogenase activity was only impacted by a high concentration of PFBA, while pyruvate dehydrogenase activity was decreased with PFBA exposure and increased with PFOA exposure. The findings from this study contribute to the knowledge of PFAS and cell interactions and reveal the potential underlying mechanisms of PFAS-induced toxicity.

Ultrasonic degradation of per-and polyfluoroalkyl substances (PFAS), aqueous film-forming foam (AFFF) and foam fractionate (FF)

The ubiquitousness of per- and polyfluoroalkyl substances (PFAS) is a big concern and PFAS remediation is urgently needed such as via degradation. While previous studies have explored ultrasonic degradation of PFAS, work evaluating the operational parameters is rare, especially concerning real wastes such as aqueous film-forming foam (AFFF) and foam fractionate (FF). This study investigates the key operational parameters affecting the degradation efficiency of PFAS, encompassing ultrasonication frequency (580-1144 kHz), power intensity (125-187.5 W), initial concentration (0.08-40 ppm), treatment duration (0.5-3 h), sample volume (100-500 mL), and PFAS structure (perfluorooctanoic acid or PFOA; perfluorooctane sulfonate or PFOS; 6:2 fluorotelomer sulfonate or 6:2 FTS). The defluorination kinetics is different from the removal/degradation kinetics due to the generation of degradation intermediates, suggesting the complex degradation mechanism, which should be evaluated to close the mass balance effectively. Notably, the optimised ultrasonic system achieves ∼125%/∼115% defluorination in AFFF/FF example wastes (compared to ∼65%/∼97% removal) despite their complex composition and the involvement of total oxidizable precursor (TOP) assay. In the meantime, a few new PFAS are detected in the post-treatments, including perfluorohexane sulfonic acid (PFHxS) and 10:2 fluorotelomer sulfonate (10:2 FTS) in the AFFF, and perfluorooctane sulfonamide (FOSA) and 8:2 fluorotelomer sulfonate (8:2 FTS) in the FF, again suggesting the complex degradation mechanism. Overall, ultrasonication is effective to degrade PFAS real example wastes, advancing its potential for scale-up applications.

Application of cobalt-cerium-iron ternary layered double hydroxide for extraction of perfluorooctane sulfonate followed by HPLC-MS/MS analysis

Herein, Ce-doped CoFe layered double hydroxide (LDH), noted as CoCeFe ternary LDH, was prepared using the co-precipitation route. Prosperous synthesis of CoFe LDH and successful partial replacement of iron cations with cerium cations in CoCeFe ternary LDH were confirmed by X-ray diffraction patterns, energy-dispersive X-ray spectroscopy, and elemental dot-mapping images. Nanosheet morphology was recognized for both CoFe LDH and CoCeFe ternary LDH from scanning electron microscopy and transmission electron microscopy micrographs. In the following, a dispersive solid phase extraction (DSPE) method was developed using the synthesized CoCeFe ternary LDH as a sorbent for extracting perfluorooctanesulfonic acid (PFOS) from wastewater samples. For the selective analysis of PFOS, high-performance liquid chromatography-tandem mass spectroscopy (HPLC-MS/MS) in multiple reaction monitoring mode was used. Analytical parameters such as the limit of detection equal to 0.02 μg/L, with a linear range of 0.05-300 μg/L, the limit of quantification equal to 0.05 μg/L, and an enrichment factor equal to 23.3 were achieved for PFOS at the optimized condition (sorbent: 5 mg of CoCeFe ternary LDH, eluent type and volume: 150 μL mobile phase, pH: 3, adsorption time: 3 min, and desorption time: 5 min). The developed strategy for the analysis of PFOS was tested in real wastewater samples, including copper mine and petrochemical wastewater. The amount of analytes in real samples was calculated using the standard addition method, and good relative recovery in the range of 86%-105% was obtained. The main novelty of this research is the application of CoCeFe ternary LDH to extract the PFOS from wastewater using the DSPE method for determination by HPLC-MS/MS.

Low-Temperature Mineralization of Fluorotelomers with Diverse Polar Head Groups

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental pollutants linked to harmful health effects. Currently employed PFAS destruction methods are energy-intensive and often produce shorter-chain and recalcitrant partially fluorinated byproducts. We report the mineralization of five fluorotelomer compounds via a base-mediated degradation using NaOH and mild temperatures (120 °C) in a mixture of DMSO:H2O (8:1 v/v). The studied fluorotelomers have varying polar head groups-carboxylic acids, sulfonic acids, alcohols, and phosphonic acids, which are the most common polar head groups used in commercial and industrial applications. The degradation intermediates and byproducts were characterized using 1H, 13C, and 19F NMR spectroscopy. Density functional theory computations at the M06-2X/6-311 + G(2d,p)-SMD-(DMSO) level were consistent with the observed intermediates and guided an overall mechanistic hypothesis. Degradation of each fluorotelomer occurs through a similar process, in which the nonfluorinated carbons and the first fluorinated carbon are cleaved from the remaining perfluoroalkyl fragment, which degrades through previously identified pathways. These findings provide important insight into PFAS degradation processes and suggest that PFAS containing at least one C-H bond within or adjacent to its fluoroalkyl chain can be degraded under these mild conditions. Many PFAS in current use as well as recalcitrant fluorinated byproducts generated from other PFAS degradation methods are candidates for this approach.

Insights into PFAS environmental fate through computational chemistry: A review

Per- and polyfluoroalkyl substances (PFAS) are widely used chemicals that exhibit exceptional chemical and thermal stability. However, their resistance to degradation has led to their widespread environmental contamination. PFAS also negatively affect the environment and other organisms, highlighting the need for effective remediation methods to mitigate their presence and prevent further contamination. Computational chemistry methods, such as Density Functional Theory (DFT) and Molecular Dynamics (MD) offer valuable tools for studying PFAS and simulating their interactions with other molecules. This review explores how computational chemistry methods contribute to understanding and tackling PFAS in the environment. PFAS have been extensively studied using DFT and MD, each method offering unique advantages and computational limitations. MD simulates large macromolecules systems however it lacks the ability model chemical reactions, while DFT provides molecular insights however at a high computational cost. The integration of DFT with MD shows promise in predicting PFAS behavior in different environments. This work summarizes reported studies on PFAS compounds, focusing on adsorption, destruction, and bioaccumulation, highlighting contributions of computational methods while discussing the need for continued research. The findings emphasize the importance of computational chemistry in addressing PFAS contamination, guiding risk assessments, and informing future research and innovations in this field.

How Per- and Poly-Fluoroalkyl Substances Affect Gamete Viability and Fertilization Capability: Insights from the Literature

There has been emerging research linking per- and poly-fluoroalkyl substances (PFAS) to gamete viability and fertility. PFAS, prevalent in the environment and water supplies, undergo slow degradation due to their C-F bond and a long half-life (2.3-8.5 years). In females, PFAS inhibit the hypothalamic-pituitary-gonadal (HPG) axis, reducing follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels, leading to the inhibition of androgen and estradiol production. PFAS have been found to cause detrimental effects on egg quality through impairing folliculogenesis. In males, PFAS can impair sperm motility and morphology: two fundamental qualities of successful fertilization. PFAS exposure has been proven to inhibit testosterone production, sperm capacitation, and acrosomal reaction. After fertilization, the results of PFAS exposure to embryos have also been investigated, showing reduced development to the blastocyst stage. The aim of this review is to report the main findings in the literature on the impact of PFAS exposure to gamete competency and fertilization capability by highlighting key studies on both male and female fertility. We report that there is significant evidence demonstrating the negative impacts on fertility after PFAS exposure. At high doses, these environmentally abundant and widespread compounds can significantly affect human fertility.

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.

Perfluorooctane sulfonate (PFOS) and its selected analogs induce various cell death types in peripheral blood mononuclear cells

The perfluoalkyl substance (PFASs) perfluorooctane sulfonate (PFOS) has been widely used in industry. However, PFOS is a persistent organic pollutant and has been gradually replaced by its short-chain analogs, perfluorohexane sulfonate (PFHxS) and perfluorobutane sulfonate (PFBS). PFASs are extremely persistent and are very frequently detected among the general population. The aim of the study was to determine the effect of selected PFASs on peripheral blood mononuclear cells (PBMCs) and the mechanisms of their action. PBMCs were exposed to PFOS, PFBS and PFHxS at concentrations ranging from 0.02 to 400 μM for 24 h, they were then tested for viability, apoptosis (changes in cytosolic calcium ions level and caspase-3, -8 and -9 activation), ferroptosis (changes in chelatable iron ions level and lipid peroxidation), and autophagy (LC3-II and Raptor level assay). PFOS exposure decreased cell viability, increased calcium ion level and caspase-8 activation; it also enhanced lipid peroxidation and increased the intracellular pool of chelatable iron ions as well as LC3-II protein content. In contrast, short-chain PFBS and PFHxS induced significant changes in the markers of apoptosis but had no substantial impact on ferroptosis or autophagy markers over a wide range of concentrations. Our results indicate that only PFOS demonstrated pro-ferroptotic and pro-autophagic potential but observed changes occurred at relatively high exposure. A short-chain substitute (PFBS) exhibited strong pro-apoptotic potential at concentrations related to occupational exposure. While the short-chain PFASs strongly affected the mitochondrial pathway of apoptosis, apoptosis itself was only induced by PFBS via the intrinsic and extrinsic pathways. It seems that the length of the carbon chain in PFASs appears to determine the cell death mechanisms activated in human PBMCs following exposure. Our findings provide a new insight into the immune toxicity mechanism induced by these compounds.

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.

The use of a fluorine mass balance to demonstrate the mineralization of PFAS by high frequency and high power ultrasound

High-frequency ultrasound (sonolysis) has been shown as a practical approach for mineralizing PFAS in highly concentrated PFAS waste. However, a fluorine mass balance approach showing complete mineralization for ultrasound treatment has not been elucidated. The impact of ultrasonic power density (W/L) and the presence of co-occurring PFAS on the degradation of individual PFAS are not well understood. In this research, the performance of a 10L sonochemical reactor was assessed for treating synthetic high-concentration PFAS waste with carboxylic and sulfonic perfluoroalkyl surfactants ranging in chain length from four to eight carbons at three different initial concentrations: 6, 55, 183 μM. The mass balance for fluorine was performed using three analytical techniques: triple quadrupole liquid chromatography-mass spectrometry, a fluoride ion selective electrode, and 19F nuclear magnetic resonance. The test results showed near complete mineralization of PFAS in the waste without the formation of intermediate fluorinated by-products. The PFAS mineralization efficiency of the sonolysis treatment at two different power densities for similar initial concentrations were almost identical; the G value at 145 W/L was 9.7*10-3 g/kWh, whereas the G value at 90 W/L was 9.3*10-3 g/kWh. The results of this study highlight the implications for the scalability of the sonolytic process to treat high-concentration PFAS waste.

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.

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.

Estimation of per- and polyfluoroalkyl substances (PFAS) half-lives in human studies: a systematic review and meta-analysis

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) constitute a heterogeneous group of synthetic compounds widely used in industrial applications. The estimation of PFAS half-life (t1/2) is essential to quantify their persistence, their toxicity and mechanism of action in humans.

OBJECTIVES

The purpose of this review is to summarize the evidence on PFAS half-lives in humans from the available literature, and to investigate the limitations and uncertainties characterizing half-life estimation.

METHODS

The search was conducted on PubMed, Scopus, and Embase databases up to July 03, 2023 and was aimed at identifying all papers that estimated PFAS half-life in human populations. We excluded studies on temporal trends or providing estimates of half-life based solely on renal clearance. As persistent and ongoing exposures can influence half-life estimation, we decided to include only studies that were conducted after the main source of exposure to PFAS had ceased. A random-effects meta-analysis was conducted on studies that reported perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS) or perfluorohexanesulfonic acid (PFHxS) half-life estimation. Risk of bias was evaluated using the OHAT tool.

RESULTS

A total of 13 articles were included in the review, with 5 studies conducted in exposed general populations and 8 studies conducted in exposed workers; the estimated mean half-life ranged from 1.48 to 5.1 years for PFOA, from 3.4 to 5.7 years for total PFOS, and from 2.84 to 8.5 years for PFHxS. High heterogeneity among studies was observed; potential reasons include the variability among the investigated populations, discrepancies in considering ongoing exposures, variability in PFAS isomeric compositions, accounting for background exposure, time since exposure stopped and methods used for half-life estimation.

DISCUSSION

Despite the efforts made to better understand PFAS toxicokinetics, further studies are needed to identify important characteristics of these persistent chemicals. Biomonitoring studies should focus on persistent and unaccounted sources of exposure to PFAS and on individual characteristics potentially determining half-life, to ensure accurate estimates.

Exposure to perfluoroalkyl and polyfluoroalkyl substances and pediatric obesity: a systematic review and meta-analysis

INTRODUCTION

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are potentially obesogenic for children. We undertook a systematic review to synthesize this literature and explore sources of heterogeneity in previously published epidemiological studies.

METHODS

Studies that collected individual-level PFAS and anthropometric data from children up to 12 years of age were identified by searching six databases. We excluded studies that only evaluated obesity measures at the time of birth. A full-text review and quality assessment of the studies was performed using the Office of Health Assessment and Translation (OHAT) criteria. Forest plots were created to summarize measures of association and assess heterogeneity across studies by chemical type and exposure timing. Funnel plots were used to assess small-study effects.

RESULTS

We identified 24 studies, of which 19 used a cohort design. There were 13 studies included in the meta-analysis examining various chemicals and outcomes. Overall prenatal exposures to four different types of PFAS were not statistically associated with changes in body mass index (BMI) or waist circumference. In contrast, for three chemicals, postnatal exposures were inversely related to changes in BMI (i.e., per log10 increase in PFOS: BMI z-score of -0.16 (95% CI: -0.22, -0.10)). There was no substantial heterogeneity in the reported measures of association within prenatal and postnatal subgroups. We observed modest small-study effects, but correction for these effects using the Trim and Fill method did not change our summary estimate(s).

CONCLUSION

Our review found no evidence of a positive association between prenatal PFAS exposure and pediatric obesity, whereas an inverse association was found for postnatal exposure. These findings should be interpreted cautiously due to the small number of studies. Future research that can inform on the effects of exposure mixtures, the timing of the exposure, outcome measures, and the shape of the exposure-response curve is needed.

Is it raining PFAS in France? An analysis of 52 PFAS at nanogram per liter levels in French rainwaters during autumn season

Per- and polyfluoroalkyl substances (PFAS) are of increasing concern due to their pervasive nature, high persistence, and their impacts on human health and the environment. Many studies have attempted to assess the presence of PFAS along the water cycle, but few have analyzed rainwater PFAS content and its contribution to water contamination. The present study aims to improve knowledge by providing the first analysis of PFAS rainwater samples from France. A total of 52 PFAS were analyzed at nanogram per liter levels in rainwater samples collected in 14 locations in France using a cutting-edge liquid chromatography-tandem mass spectrometry (LC/MS/MS) method for multiresidue determination. Depending on the quantity of rainwater collected, the PFAS concentrations were analyzed either by direct injection or after solid-phase extraction (SPE), allowing to quantify 20 PFAS with a limit of quantification (LOQ) ≤ 100 ng/L and 52 PFAS with a LOQ ≤ 1 ng/L, respectively. For the five locations for which the collected samples were analyzed by direct injection, no PFAS could be detected (i.e., their concentrations in the samples were below the LOQs of the method). The samples from four locations out of the nine analyzed by SPE-LC/MS/MS show results above the method's LOQs for up to 10 PFAS. Among the quantified PFAS, three compounds (perfluorononanoic acid, perfluoroundecanoic acid, and perfluorohexanoic acid) have been found to be of most significance. These results bring out the presence of PFAS in rainwater samples in France, highlighting the need for PFAS environmental surveillance and risk assessment and the necessity of continuous improvement of existing analysis methods.

Adsorption of per- and polyfluoroalkyl substances (PFAS) from water with porous organic polymers

Per- and polyfluoroalkyl substances (PFAS) are man-made environmental contaminants causing increasing global concern due to their adverse effect on environmental and human health. Conventional treatment methods are ineffective in removing short-chain PFAS because they are persistent and recalcitrant to treatment. This study evaluated the performance of a structurally-tunable and chemically-stable porous organic polymer (POP) for PFAS removal under realistic environmental conditions. The POP demonstrated an exceptionally high removal efficiency (>95%) within 15 min when the initial PFAS concentration was approximately 400 ng/L. The adsorption of PFAS on the POP was not significantly affected by changes in solution pH within the range of 5-9. The common co-contaminants in water competed with short-chain PFAS for active sites during the adsorption process following the order of natural organic matter (NOM), long-chain PFAS, and Cl-. The Freundlich-type model could predict the multicomponent interactions well with a R2 value above 0.91. The spent POP was effectively regenerated using a mixture of the 10% NaCl and 30% methanol solution and the PFAS removal maintained at 90% through five adsorption and desorption cycles. The characteristics of the designed POP make it a highly promising and stable absorbent. It enables fast and effective removal of short-chain PFAS.

A critical review of perfluoroalkyl and polyfluoroalkyl substances (PFAS) landfill disposal in the United States

Landfills manage materials containing per- and polyfluoroalkyl substances (PFAS) from municipal solid waste (MSW) and other waste streams. This manuscript summarizes state and federal initiatives and critically reviews peer-reviewed literature to define best practices for managing these wastes and identify data gaps to guide future research. The objective is to inform stakeholders about waste-derived PFAS disposed of in landfills, PFAS emissions, and the potential for related environmental impacts. Furthermore, this document highlights data gaps and uncertainties concerning the fate of PFAS during landfill disposal. Most studies on this topic measured PFAS in liquid landfill effluent (leachate); comparatively fewer have attempted to estimate PFAS loading in landfills or other effluent streams such as landfill gas (LFG). In all media, the reported total PFAS heavily depends on waste types and the number of PFAS included in the analytical method. Early studies which only measured a small number of PFAS, predominantly perfluoroalkyl acids (PFAAs), likely report a significant underestimation of total PFAS. Major findings include relationships between PFAS effluent and landfill conditions - biodegradable waste increases PFAS transformation and leaching. Based on the results of multiple studies, it is estimated that 84% of PFAS loading to MSW landfills (7.2 T total) remains in the waste mass, while 5% leaves via LFG and 11% via leachate on an annual basis. The environmental impact of landfill-derived PFAS has been well-documented. Additional research is needed on PFAS in landfilled construction and demolition debris, hazardous, and industrial waste in the US.

Physicochemical properties and interactions of perfluoroalkyl substances (PFAS) - Challenges and opportunities in sensing and remediation

Per- and polyfluoroalkyl substances (PFAS) is a class of persistent organic pollutants that presents health and environmental risks. PFAS are ubiquitously present in the environment, but current remediation technologies are ineffective in degrading them into innocuous chemicals, especially high energy degradation processes often generate toxic short chain intermediates. Therefore, the best remediation strategy is to first detect the source of pollution, followed by capturing and mineralising or recycling of the compounds. The main objective of this article is to summarise the unique physicochemical properties and to critically review the intermolecular and intramolecular physicochemical interactions of PFAS, and how these interactions can become obstacles; and at the same time, how they can be applied to the PFAS sensing, capturing, and recycling process. The physicochemical interactions of PFAS chemicals are being reviewed in this paper includes, (1) fluorophilic interactions, (2) hydrophobic interactions, (3) electrostatic interactions and cation bridging, (4) ionic exchange and (5) hydrogen bond. Moreover, all the different influential factors to these interactions have also been reported. Finally, properties of these interactions are compared against one another, and the recommendations for future designs of affinity materials for PFAS have been given.

Synthetic Advantages of Defluorinative C-F Bond Functionalization

Much progress has been made in the development of methods to both create compounds that contain C-F bonds and to functionalize C-F bonds. As such, C-F bonds are becoming common and versatile synthetic functional handles. This review summarizes the advantages of defluorinative functionalization reactions for small molecule synthesis. The coverage is organized by the type of carbon framework the fluorine is attached to for mono- and polyfluorinated motifs. The main challenges, opportunities and advances of defluorinative functionalization are discussed for each class of organofluorine. Most of the text focuses on case studies that illustrate how defluorofunctionalization can improve routes to synthetic targets or how the properties of C-F bonds enable unique mechanisms and reactions. The broader goal is to showcase the opportunities for incorporating and exploiting C-F bonds in the design of synthetic routes, improvement of specific reactions and advent of new methods.

Per- and polyfluoroalkyl substances (PFASs) in consumable species and food products

Per- and polyfluoroalkyl substances (PFASs) are a group of thousands of manmade chemicals widely used in consumer products and industrial processes. Toxicological studies have suggested that exposure to PFASs may lead to several adverse effects, including infertility and cancer development. In light of their widespread use, the contamination of food products has created health concerns in sites directly influenced by industrial and anthropogenic activity. In the present contribution, the current knowledge of PFAS contamination was systematically reviewed in order to provide with the knowledge gaps and main sources of contamination, as well as critically evaluate estimated dietary intake and relative risk values of the consulted studies. Legacy PFASs remain the most abundant despite their production restrictions. Edible species from freshwater bodies exhibit higher PFAS concentrations than marine species, probably due to low hydrodynamics and dilution in lentic ecosystems. Studies in food products from multiple sources, including aquatic, livestock, and agricultural, agree that the proximity to factories and fluorochemical industries rendered significantly higher and potentially hazardous PFAS contamination. Short-chain PFAS are suggested as chemicals of emerging concern to food security. However, the environmental and toxicological implications of short-chain congeners are not fully understood and, thus, much research is needed in this sense.

Contributions of reactor geometry and ultrasound frequency on the efficieny of sonochemical reactor

An intermediate-scale reactor with 10L capacity and two transducers operating at 700 and 950 kHz frequencies was developed to study the scalability of the sonolytic destruction of Per and Polyfluoroalkyl substance (PFAS). The impact of frequency, height of liquid or power density, and transducer position on reactor performance was evaluated with the potassium iodide (KI) oxidation and calorimetric power. The dual frequency mode of operation has a synergistic effect based on the triiodide concentration, and calorimetric power. The triiodide concentration, and calorimetric power were higher in this mode compared to the combination of both frequencies operating individually. The sonochemical efficiency for an intermediate-scale reactor (10L) was similar that obtained from a bench-scale reactor (2L), showing the scalability of the sonolytic technology. The placement of the transducer at the bottom or side wall of the reactor had no significant impact on the sonochemical reactivity. The superposition of the ultrasonic field from the dual transducer mode (side and bottom) did not produce a synergistic effect compared to the single transducer mode (bottom or side). This can be attributed to a disturbance due to the interaction of ultrasonic fields of two frequencies from each transducer. With the encouraging results scaling up is in progress for site implementation.

Pyrene-Containing Polyamines as Fluorescent Receptors for Recognition of PFOA in Aqueous Media

The globally widespread perfluorooctanoic acid (PFOA) is a concerning environmental contaminant, with a possible toxic long-term effects on the environment and human health The development of sensible, rapid, and low-cost detection systems is a current change in modern environmental chemistry. In this context, two triamine-based chemosensors, L1 and L2, containing a fluorescent pyrene unit, and their Zn(II) complexes are proposed as fluorescent probes for the detection of PFOA in aqueous media. Binding studies carried out by means of fluorescence and NMR titrations highlight that protonated forms of the receptors can interact with the carboxylate group of PFOA, thanks to salt bridge formation with the ammonium groups of the aliphatic chain. This interaction induces a decrease in the fluorescence emission of pyrene at neutral and slightly acidic pH values. Similarly, emission quenching has also been observed upon coordination of PFOA by the Zn(II) complexes of the receptors. These results evidence that simple polyamine-based molecular receptors can be employed for the optical recognition of harmful pollutant molecules, such as PFOA, in aqueous media.

A Path to a Reduction in Micro and Nanoplastics Pollution

Microplastics (MP) are plastic particles less than 5 mm in size. There are two categories of MP: primary and secondary. Primary or microscopic-sized MP are intentionally produced material. Fragmentation of large plastic debris through physical, chemical, and oxidative processes creates secondary MP, the most abundant type in the environment. Microplastic pollution has become a global environmental problem due to their abundance, poor biodegradability, toxicological properties, and negative impact on aquatic and terrestrial organisms including humans. Plastic debris enters the aquatic environment via direct dumping or uncontrolled land-based sources. While plastic debris slowly degrades into MP, wastewater and stormwater outlets discharge a large amount of MP directly into water bodies. Additionally, stormwater carries MP from sources such as tire wear, artificial turf, fertilizers, and land-applied biosolids. To protect the environment and human health, the entry of MP into the environment must be reduced or eliminated. Source control is one of the best methods available. The existing and growing abundance of MP in the environment requires the use of multiple strategies to combat pollution. These strategies include reducing the usage, public outreach to eliminate littering, reevaluation and use of new wastewater treatment and sludge disposal methods, regulations on macro and MP sources, and a wide implementation of appropriate stormwater management practices such as filtration, bioretention, and wetlands.

Effect of clay content on the mobilization efficiency of per- and polyfluoroalkyl substances (PFAS) from soils by electrokinetics and hydraulic flushing

The need for the efficient remediation of soils impacted by per- and polyfluoroalkyl substances (PFAS) is substantially growing because of the notable upsurge in societal and regulatory awareness of this class of chemicals. To remediate PFAS-contaminated soils using mobilization approaches, the choice of appropriate techniques highly depends on the soil's composition, particularly the clay content, which significantly affects the soil's permeability. Here, we investigated the PFAS mobilization efficiency from soils with different clay contents by using two techniques: electrokinetic (EK) remediation and hydraulic flushing. Artificial kaolinite was added to a loamy sand soil to prepare four soil blends with clay contents of 5, 25, 50, and 75%, each contaminated with perfluorooctanoic acid (PFOA) and perfulorooctanesulfonic acid (PFOA) at 10,000 μg/kg. EK remediation was conducted by applying a low voltage (30 V) with a current of 100 mA, and hydraulic flushing was carried out by applying a hydraulic gradient (HG) with a slope of 6.7%. Results show that, with a 14-day treatment duration, the EK-mobilization efficiency was enhanced substantially with the increase of clay content (removal of PFOS increased from 20% at 5% clay to 80% at 75% clay), most likely due to the increase of electroosmotic flow due to the higher content of particles having a zeta potential (i.e., clay). For HG, increasing the clay content significantly suppressed the mobilization of PFAS (removal of PFOS decreased from 40% at 5% clay to 10% at 75% clay) due to a notable decrease in the soil's permeability. Based on the results, applying hydraulic flushing and washing techniques for mobilizing PFAS would be appropriate when treating permeable soils with a maximum clay content of about 25%; otherwise, other suitable mobilization techniques such as EKs should be considered.

The use of gas chromatography - high resolution mass spectrometry for suspect screening and non-targeted analysis of per- and polyfluoroalkyl substances

This study is a workflow development for the analysis, identification, and categorization of per- and polyfluoroalkyl substances (PFAS) using gas chromatography-high resolution mass spectrometry (GC-HRMS) with non-targeted analysis (NTA) and suspect screening techniques. The behavior of various PFAS in a GC-HRMS was studied with regards to retention indices, ionization susceptibility, fragmentation patterns, etc. A custom PFAS database was constructed from 141 diverse PFAS. The database contains mass spectra from electron ionization (EI) mode, as well as MS and MS/MS spectra from positive and negative chemical ionization (PCI and NCI, respectively) modes. Common fragments of PFAS were identified across a diverse set of 141 PFAS analyzed. A workflow for suspect screening of PFAS and partially fluorinated products of incomplete combustion/destruction (PICs/PIDs) was developed which utilized both the custom PFAS database and external databases. PFAS and other fluorinated compounds were identified in both a challenge sample (designed to test the identification workflow) and incineration samples suspected to contain PFAS and fluorinated PICs/PIDs. The challenge sample resulted in a 100% true positive rate (TPR) for PFAS which were present in the custom PFAS database. Several fluorinated species were tentatively identified in the incineration samples using the developed workflow.

Preliminary Study on the Protective Effects and Molecular Mechanism of Procyanidins against PFOS-Induced Glucose-Stimulated Insulin Secretion Impairment in INS-1 Cells

This study aimed to investigate the effects of perfluorooctanesulfonic acid (PFOS) exposure on glucose-stimulated insulin secretion (GSIS) of rat insulinoma (INS-1) cells and the potential protective effects of procyanidins (PC). The effects of PFOS and/or PC on GSIS of INS-1 cells were investigated after 48 h of exposure (protein level: insulin; gene level: glucose transporter 2 (Glut2), glucokinase (Gck), and insulin). Subsequently, the effects of exposure on the intracellular reactive oxygen species (ROS) activity were measured. Compared to the control group, PFOS exposure (12.5, 25, and 50 μM) for 48 h had no significant effect on the viability of INS-1 cells. PFOS exposure (50 μM) could reduce the level of insulin secretion and reduce the relative mRNA expression levels of Glut2, Gck, and insulin. It is worth noting that PC could partially reverse the damaging effect caused by PFOS. Significantly, there was an increase in ROS after exposure to PFOS and a decline after PC intervention. PFOS could affect the normal physiological function of GSIS in INS-1 cells. PC, a plant natural product, could effectively alleviate the damage caused by PFOS by inhibiting ROS activity.

Toxicity of Per- and Polyfluoroalkyl Substances to Aquatic Invertebrates, Planktons, and Microorganisms

Per- and polyfluoroalkyl substances (PFASs), recognized worldwide as emerging pollutants, may pose a substantial threat to human health and our environment due to their stability, high concentrations, wide distribution, and easy accumulation. Ever since perfluorooctane sulfonate and perfluorooctanoic acid were recognized by the Stockholm Convention on Persistent Organic Pollutants, the public has become increasingly concerned about potential contamination and the environmental risks associated with PFASs. Ubiquitous PFAS contamination of drinking water, groundwater, surface water, and sediment has been detected, especially in areas with rapid industrial and economic development. Its accumulation in living organisms and foods has accentuated the importance of investigations into aquatic organisms at the bottom of the food chain, as the stability and integrity of the food web as well as the population quantity and structure of the aquatic ecosystem may be affected. This review provides a comprehensive summary of the toxic and toxicity-related effects of PFASs on aquatic plankton, aquatic invertebrates and microorganisms, the characteristics of different target aquatic organisms in toxicity investigations, and a feasibility evaluation of PFAS substitutes to provide valuable suggestions for further utilization and regulation of PFASs and their substitutes.

A Review of PFAS Destruction Technologies

Per- and polyfluoroalkyl substances (PFASs) are a family of highly toxic emerging contaminants that have caught the attention of both the public and private sectors due to their adverse health impacts on society. The scientific community has been laboriously working on two fronts: (1) adapting already existing and effective technologies in destroying organic contaminants for PFAS remediation and (2) developing new technologies to remediate PFAS. A common characteristic in both areas is the separation/removal of PFASs from other contaminants or media, followed by destruction. The widely adopted separation technologies can remove PFASs from being in contact with humans; however, they remain in the environment and continue to pose health risks. On the other hand, the destructive technologies discussed here can effectively destroy PFAS compounds and fully address society's urgent need to remediate this harmful family of chemical compounds. This review reports and compare widely accepted as well as emerging PFAS destruction technologies. Some of the technologies presented in this review are still under development at the lab scale, while others have already been tested in the field.

Exposure to a mixture of per-and polyfluoroalkyl substances modulates pulmonary expression of ACE2 and circulating hormones and cytokines

Genetic and environmental factors impact on the interindividual variability of susceptibility to communicable and non-communicable diseases. A class of ubiquitous chemicals, Per- and polyfluoroalkyl substances (PFAS) have been linked in epidemiological studies to immunosuppression and increased susceptibility to viral infections, but possible mechanisms are not well elucidated. To begin to gain insight into the role of PFAS in susceptibility to one such viral infection, Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), male and female C57BL/6 J mice were exposed to control water or a mixture of 5 PFAS (PFOS, PFOA, PFNA, PFHxS, Genx) for 12 weeks and lungs were isolated for examination of expression of SARS-CoV-2-related receptors Angiotensin-Converting Enzyme 2 (ACE2) and others. Secondary analyses included circulating hormones and cytokines which have been shown to directly or indirectly impact on ACE2 expression and severity of viral infections. Changes in mRNA and protein expression were analyzed by RT-qPCR and western blotting and circulating hormones and cytokines were determined by ELISA and MESO QuickPlex. The PFAS mixture decreased Ace2 mRNA 2.5-fold in male mice (p < 0.0001), with no significant change observed in females. In addition, TMPRSS2, ANPEP, ENPEP and DPP4 (other genes implicated in COVID-19 infection) were modulated due to PFAS. Plasma testosterone, but not estrogen were strikingly decreased due to PFAS which corresponded to PFAS-mediated repression of 4 representative pulmonary AR target genes; hemoglobin, beta adult major chain (Hbb-b1), Ferrochelatase (Fech), Collagen Type XIV Alpha 1 Chain (Col14a1), 5'-Aminolevulinate Synthase 2 (Alas2). Finally, PFAS modulated circulating pro and anti-inflammatory mediators including IFN-γ (downregulated 3.0-fold in females; p = 0.0301, 2.1-fold in males; p = 0.0418) and IL-6 (upregulated 5.6-fold in males; p = 0.030, no change in females). In conclusion, our data indicate long term exposure to a PFAS mixture impacts mechanisms related to expression of ACE2 in the lung. This work provides a mechanistic rationale for important future studies of PFAS exposure and subsequent viral infection.

High-temperature decomposition chemistry of trimethylsiloxane surfactants, a potential Fluorine-Free replacement for fire suppression

Per- and polyfluoroalkyl substances (PFAS) have become global environmental contaminants due to being notoriously difficult to degrade, and it has become increasingly important to employ suitable PFAS alternatives, especially in aqueous film-forming foams (AFFF). Trimethylsiloxane (TriSil) surfactants are potential fluorine-free replacements for PFAS in fire suppression technologies. Yet because these compounds may be more susceptible to high-temperature decomposition, it is necessary to assess the potential environmental impact of their thermal degradation products. Our study analyzes the high-temperature degradation of a truncated trimethylsiloxane (TriSil-1n) surfactant based on quantum mechanical methods. The degradation chemistry of TriSil-1n was studied through radical formation and propagation initiated from two prominent pathways (unimolecular and bimolecular reactions) at both 298 K and 1200 K, a relevant temperature in flames and thermal incinerators. Regardless of the pathway taken and temperature, all radical intermediates stemmed from the polyethylene glycol chain and primarily formed stable polydimethylsiloxanes (PDMS) and small organics such as ethylene, formaldehyde, and acetaldehyde, among other products. The major degradation products of TriSil-1n resulting from high-temperature thermal degradation as predicted by this study would be relatively less harmful to the environment compared to PFAS incineration/combustion products from previous research, supporting the replacement of PFAS with TriSil surfactants.

Interlaboratory Comparison Investigations (ICIs) and External Quality Assurance Schemes (EQUASs) for human biomonitoring of perfluoroalkyl substances (PFASs) in serum as part of the quality assurance programme under HBM4EU

Perfluoroalkyl substances (PFASs) are of very high concern due to their persistence and accumulative behaviour as well as their manifold adverse health effects. Human biomonitoring (HBM) based on the determination of PFASs in serum samples is an adequate and established strategy for exposure and risk assessment of the population. The suspected health risks associated with exposure levels in the general population call for reliable HBM data verified by Quality Assurance and Quality Control (QA/QC) measures. PFASs were among the chemicals selected as priority substances in HBM4EU, a pan-European project to harmonize and advance HBM within 30 European countries. For this purpose, the analytical comparability and accuracy of PFASs-analysing laboratories was assessed in a QA/QC programme comprising Interlaboratory Comparison Investigations (ICIs) and External Quality Assurance Schemes (EQUASs). This paper presents the evaluation process and discusses the results of four ICI/EQUAS rounds for the determination of eight perfluoroalkyl carboxylic acids and four perfluoroalkyl sulfonic acids (PFBS, PFHxS, PFHpS, PFOS) in serum. All 21 participating laboratories achieved satisfactory results for at least six of these biomarkers, although low limits of quantification (of about 0.1 μg/L) were required to quantify serum PFAS levels at general population exposure levels. The mean relative standard deviation of the participants' results (study RSD_R) significantly improved from 22 % to 13 % over all PFAS biomarkers in the course of the four rounds. This QA/QC programme succeeded in establishing a network of laboratories with high analytical comparability and accuracy for the analysis of PFASs across 12 European countries.

Concentrations of perfluoroalkyl and polyfluoroalkyl substances before and after full-scale landfill leachate treatment

Many consumer and industrial products, industrial wastes and dewatered sludge from municipal wastewater treatment plants containing per- and polyfluoroalkyl substances (PFAS) are disposed of in landfills at the end of their usage, with PFAS in these products leached into landfill leachates. On-site leachate treatment is one possible method to reduce PFAS in leachates. Many landfills are equipped with on-site leachate treatment systems, but few full-scale facilities have been systematically evaluated for PFAS concentration changes. The objective of this study was to evaluate a cross-section of full-scale on-site landfill treatment systems to measure changes in PFAS concentrations. Leachate samples were collected before and after treatment from 15 facilities and were evaluated for 26 PFAS, including 11 perfluoroalkyl carboxylic acids (PFCAs), 7 perfluoroalkyl sulfonic acids (PFSAs), and 8 perfluoroalkyl acid precursors (PFAA-precursors). Transformation of precursors was evaluated by the total oxidizable precursor (TOP) assay. Results showed no obvious reductions in total measured PFAS (∑26PFAS) for on-site treatment systems including ponds, aeration tanks, powdered activated carbon (PAC), and sand filtration. Among evaluated on-site treatment systems, only systems fitted with reverse osmosis (RO) showed significant reductions (98-99 %) of ∑26PFAS in the permeate. Results from the TOP assay showed that untargeted PFAA-precursors converted into targeted short-chain PFCAs increasing ∑26PFAS in oxidized samples by 30 %, on average. Overall, results of this study confirm the efficacy of RO systems and suggest the presence of additional precursors beyond those measured in this study.

Towards Solving the PFAS Problem: The Potential Role of Metal-Organic Frameworks

Per- and polyfluoroalkyl substances (PFAS) are a group of recalcitrant molecules that have been used since the 1940s in a variety of applications. They are now linked to a host of negative health outcomes and are extremely resistant to degradation under environmental conditions. Currently, membrane technologies or adsorbents are used to remediate contaminated water. These techniques are either inefficient at capturing smaller PFAS molecules, have high energy demands, or result in concentrated waste that must be incinerated at high temperatures. This Review focuses on what role metal-organic frameworks (MOFs) may play in addressing the PFAS problem. Specifically, how the unique properties of MOFs such as their well-defined pore sizes, ultra-high internal surface area, and tunable surface chemistry may be a sustainable solution for PFAS contamination.

Changing bioavailability of per- and polyfluoroalkyl substances (PFAS) to plant in biosolids amended soil through stabilization or mobilization

Biosolids containing per- and polyfluoroalkyl substances (PFAS) could contaminate the receiving environments once they are land applied. In this study, we evaluated the feasibility of controlling the bioavailability of PFAS in biosolids to timothy-grass through stabilization or mobilization approaches. Stabilization was accomplished by adding a sorbent (i.e. granular activated carbon (GAC), RemBind, biochar) to biosolids, while mobilization was achieved by adding a surfactant, sodium dodecyl sulphate (SDS), to biosolids. The results showed that the ΣPFAS concentration in grass shoots grown in biosolids amended soil treated by GAC or RemBind at 2% was only 2.77% and 3.35% of the ΣPFAS concentration detected in shoots grown in biosolids amended soil without a sorbent, respectively, indicating the effectiveness of GAC and RemBind for stabilizing PFAS and reduce their bioavailability. On the other hand, mobilization by adding SDS to biosolids at a dose range of 10-100 mg/kg significantly increased the plant uptake of ΣPFAS by 15.48%-108.57%. Thus, mobilization by adding SDS could be a valuable approach for enhancing the PFAS removal if phytoremediation is applied. Moreover, higher rate of PFAS uptake took place after grass cutting was observed in this study. Thus, proper mowing and regrowth of timothy-grass could lead to efficient and cost-effective removal of PFAS from biosolids amended soil through phytoremediation and leave the site clean to be used for other purposes.