A Never-Ending Story of Per- and Polyfluoroalkyl Substances (PFASs)?

Per- and polyfluoroalkyl substances alter innate immune function: evidence and data gaps

Per- and polyfluoroalkyl substances (PFASs) are a large class of compounds used in a variety of processes and consumer products. Their unique chemical properties make them ubiquitous and persistent environmental contaminants while also making them economically viable and socially convenient. To date, several reviews have been published to synthesize information regarding the immunotoxic effects of PFASs on the adaptive immune system. However, these reviews often do not include data on the impact of these compounds on innate immunity. Here, current literature is reviewed to identify and incorporate data regarding the effects of PFASs on innate immunity in humans, experimental models, and wildlife. Known mechanisms by which PFASs modulate innate immune function are also reviewed, including disruption of cell signaling, metabolism, and tissue-level effects. For PFASs where innate immune data are available, results are equivocal, raising additional questions about common mechanisms or pathways of toxicity, but highlighting that the innate immune system within several species can be perturbed by exposure to PFASs. Recommendations are provided for future research to inform hazard identification, risk assessment, and risk management practices for PFASs to protect the immune systems of exposed organisms as well as environmental health.

Fast analysis of short-chain and ultra-short-chain fluorinated organics in water by on-line extraction coupled to HPLC-HRMS

A rapid on-line solid-phase extraction liquid chromatography high-resolution mass spectrometry (on-line SPE-LC-HRMS) method was developed to analyze 11 ultra-short and short-chain PFAS in surface water. Analytical optimization involved screening 7 chromatographic columns and 5 on-line SPE columns, as well as evaluating SPE loading conditions, filters, sample acidification, chromatographic mobile phases, and SPE loading mobile phases. The optimized method was then applied to 44 river water samples collected in Eastern Canada, including sites near airports with fire-training areas. Among the 11 targeted PFAS, the most frequently detected were trifluoroacetic acid (TFA, 4.6-220 ng/L), perfluorobutanoic acid (PFBA, 0.85-33 ng/L), perfluoropentanoic acid (PFPeA, 1.2-2100 ng/L), trifluoromethane sulfonic acid (TMS, 0.01-4.3 ng/L), and perfluorobutane sulfonic acid (PFBS, 0.07-450 ng/L). Levels of C3-C5 perfluoroalkyl carboxylic acids (PFCAs), C2-C4 perfluoroalkyl sulfonates (PFSAs) and n:3 polyfluoroalkyl acids (n = 2,3; n:3 acids) were significantly higher in water bodies near fire-training area sites compared with rivers in urban areas. In contrast, TFA, TMS, and 1:3 acid were not significantly elevated, likely reflecting atmospheric deposition or other diffuse sources for these compounds. Nontarget and suspect screening analysis revealed an abundance of other ultra-short and short-chain PFAS in AFFF-impacted water bodies. Perfluoroalkyl sulfonamides (FASA, C2, C3, and C5), perfluoroalkyl sulfonamide propanoic acids (FASA-PrA, C1-C2) and n:3 acids (n = 1, 4, and 5) were detected for the first time in environmental surface waters.

Evaluation of 14 PFAS for permeability and organic anion transporter interactions: Implications for renal clearance in humans

Per- and polyfluoroalkyl substances (PFAS) encompass a diverse group of synthetic fluorinated chemicals known to elicit adverse health effects in animals and humans. However, only a few studies investigated the mechanisms underlying clearance of PFAS. Herein, the relevance of human renal transporters and permeability to clearance and bioaccumulation for 14 PFAS containing three to eleven perfluorinated carbon atoms (ηpfc = 3-11) and several functional head-groups was investigated. Apparent permeabilities and interactions with human transporters were measured using in vitro cell-based assays, including the MDCK-LE cell line, and HEK293 stable transfected cell lines expressing organic anion transporter (OAT) 1-4 and organic cation transporter (OCT) 2. The results generated align with the Extended Clearance Classification System (ECCS), affirming that permeability, molecular weight, and ionization serve as robust predictors of clearance and renal transporter engagement. Notably, PFAS with low permeability (ECCS 3A and 3B) exhibited substantial substrate activity for OAT1 and OAT3, indicative of active renal secretion. Furthermore, we highlight the potential contribution of OAT4-mediated reabsorption to the renal clearance of PFAS with short ηpfc, such as perfluorohexane sulfonate (PFHxS). Our data advance our mechanistic understanding of renal clearance of PFAS in humans, provide useful input parameters for toxicokinetic models, and have broad implications for toxicological evaluation and regulatory considerations.

Maternal F-53B exposure during pregnancy and lactation affects bone growth and development in male offspring

6:2 Chlorinated polyfluoroalkyl ether sulfonate (F-53B) is a new type of perfluorinated and polyfluoroalkyl substance (PFAS) that is used extensively in industry and manufacturing. F-53B causes damage to multiple mammalian organs. However, the impacts of F-53B on bone are unknown. Maternal exposure to F-53B is of particular concern because of the vulnerability of the developing fetus and newborn to contaminants from the mother. The goal of this study was to examine the impacts of maternal F-53B exposure on bone growth and development in offspring and to explore its underlying mechanisms. Herein, C57BL/6 J mice were given free access to deionized water containing 0, 0.57, or 5.7 mg/L F-53B during pregnancy and lactation. F-53B exposure resulted in impaired liver function, decreased IGF-1 secretion, dysregulation of bone metabolism and disruption of the dynamic balance between osteoblasts and osteoclasts in male offspring. F-53B inhibits longitudinal bone growth and development and causes osteoporosis in male offspring. F-53B may affect the growth and development of offspring bone via the IGF-1/OPG/RANKL/CTSK signaling pathway. This study provides new insights for the study of short stature and bone injury caused by F-53B.

Prenatal per- and polyfluoroalkyl substances (PFAS) and maternal oxidative stress: Evidence from the LIFECODES study

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals linked to adverse pregnancy outcomes. Although their underlying biological mechanisms are not fully understood, evidence suggests PFAS may disrupt endocrine functions and contribute to oxidative stress (OS) and inflammation.

OBJECTIVE

We examined associations between early pregnancy PFAS exposure and OS biomarkers, exploring potential effect modifications by fetal sex and maternal race.

METHODS

We used data from 469 LIFECODES participants with measured plasma PFAS (median 10 weeks gestation) and repeated measures (median 10, 18, 26, and 35 weeks gestation) of urinary OS biomarkers [8-iso-prostaglandin-F2α (8-isoprostane) and 8-hydroxydeoxyguanosine (8-OHdG)]. Protein damage biomarkers (chlorotyrosine, dityrosine, and nitrotyrosine) were additionally measured in plasma from a subset (N = 167) during the third visit. Associations between each PFAS and OS biomarkers were examined using linear mixed-effects models and multivariable linear regressions, adjusting for potential confounders, including maternal age, race, education level, pre-pregnancy BMI, insurance status, and parity. Effect modifications were evaluated by including an interaction term between each PFAS and fetal sex or maternal race in the models.

RESULTS

We observed significant positive associations between PFOS and 8-isoprostane, with a 9.68% increase in 8-isoprostane levels (95% CI: 0.10%, 20.18%) per interquartile range increase in PFOS. In contrast, PFUA was negatively associated [9.32% (95% CI: -17.68%, -0.11%)], while there were suggestive positive associations for MPAH and PFOA with 8-isoprostane. The associations of several PFAS with 8-OHdG varied by fetal sex, showing generally positive trends in women who delivered females, but negative or null in those who delivered males. No significant effect modification by maternal race was observed.

CONCLUSIONS

This study provides evidence linking PFAS exposure to OS during pregnancy, with potential sex-specific effects of certain PFAS on 8-OHdG. Further research should explore additional OS/inflammatory biomarkers and assess the modifying effects of dietary and behavioral patterns across diverse populations.

Unveiling the intricate connection between per- and polyfluoroalkyl substances and prostate hyperplasia

The presence of perfluoroalkyl and polyfluoroalkyl substances (PFAS) in various everyday products has raised concerns about their potential impact on prostate health. This study aimed to investigate the effects of different types of PFAS on prostate health, including PFDeA, PFOA, PFOS, PFHxS, and PFNA. To assess the relationship between PFAS exposure and prostate injury, machine learning algorithms were employed to analyze prostate-specific antigen (PSA) metrics. The analysis revealed a linear and positive dose-dependent association between PFOS and the ratio of free PSA to total PSA (f/tPSA). Non-linear dose-response relationships were observed between the other four types of PFAS and the f/tPSA ratio. Additionally, the analysis showed a positive association between the mixture of PFAS and prostate hyperplasia, with PFNA having the highest impact followed by PFOS. These findings suggest that elevated serum levels of PFDeA, PFOA, PFOS, and PFNA are linked to prostate hyperplasia. Therefore, this study utilized advanced machine learning techniques to uncover potential hazardous effects of PFAS exposure on prostate health, specifically the positive association between PFAS and prostate hyperplasia.

The boom era of emerging contaminants: A review of remediating agricultural soils by biochar

Emerging contaminants (ECs) are widely sourced persistent pollutants that pose a significant threat to the environment and human health. Their footprint spans global ecosystems, making their remediation highly challenging. In recent years, a significant amount of literature has focused on the use of biochar for remediation of heavy metals and organic pollutants in soil and water environments. However, the use of biochar for the remediation of ECs in agricultural soils has not received as much attention, and as a result, there are limited reviews available on this topic. Thus, this review aims to provide an overview of the primary types, sources, and hazards of ECs in farmland, as well as the structure, functions, and preparation types of biochar. Furthermore, this paper emphasizes the importance and prospects of three remediation strategies for ECs in cropland: (i) employing activated, modified, and composite biochar for remediation, which exhibit superior pollutant removal compared to pure biochar; (ii) exploring the potential synergistic efficiency between biochar and compost, enhancing their effectiveness in soil improvement and pollution remediation; (iii) utilizing biochar as a shelter and nutrient source for microorganisms in biochar-mediated microbial remediation, positively impacting soil properties and microbial community structure. Given the increasing global prevalence of ECs, the remediation strategies provided in this paper aim to serve as a valuable reference for future remediation of ECs-contaminated agricultural lands.

Spatial distribution, source, and fate of per- and polyfluoroalkyl substances in the surrounding environment of closed and converted fluorochemical factories in Fujian, China

Following the closure of perfluorooctanesulfonic acid (PFOS) production to comply with the Stockholm Convention regulations or restrictions, manufacturers have shifted to developing short-chain alternatives like perfluorobutane sulfonic acid (PFBS). However, limited research has been conducted to evaluate the impact of this transition on the surrounding environment. This study focused on the spatial distribution, source, and fate of 18 per- and polyfluoroalkyl substances (PFAS) in the surrounding environment of the closure and transformation of two PFAS manufacturing plants in Fujian, China. The total concentrations of PFAS in surface water, sediment, and fish were within the range of 48.9-72,400 ng/L, 0.930-57.6 ng/g dw, and 3.33-1245 ng/g dw, respectively. The predominant compounds were PFBS, PFOS, and perfluorooctanoic acid (PFOA) among the three matrices. Principal component analysis highlighted significant differences in PFAS profiles across different regions of the Futun River, suggesting diverse sources of PFAS. Source apportionment indicated that despite being closed or converted for almost three years, the two factories still significantly impacted the surrounding environment. The shutdown factory mainly released PFAS characterized by perfluoroalkyl sulfonic acids. In contrast, the PFAS were released from conversion plant with the fingerprint being PFBS and perfluoroalkyl carboxylic acids. The conversion of the factories has resulted in the coexistence of long-chain and short-chain PFAS, which has complicated the composition of PFAS in the environment. As sewage treatment plant could not effectively remove PFBS and perfluorobutanoic acid (PFBA) in wastewater, and due to their strong migration ability, these chemicals had a wider impact range, increasing the difficulty of environmental restoration and management. Risk assessment showed that PFAS downstream of the two factories posed high or moderate ecological risks. Specifically, PFBS, PFOS, and PFOA displayed the highest risk quotients and should be paid further attention.

Intense Turbulent Bursts Promote the Release of Perfluoroalkyl Acids from Sediments at High Flow Velocity

Despite frequent detection of high levels of perfluoroalkyl acids (PFAAs) in sediments, research on the environmental fate of PFAAs in sediments, particularly under hydrodynamic conditions, is rather limited, challenging effective management of PFAA loadings. Therefore, this study investigated the release and transport of 15 PFAAs in sediments under environmentally relevant flow velocities using recirculating flumes and revealed the underlying release mechanisms by identifying related momentum transfer. An increased velocity enhanced the release magnitude of total PFAAs by a factor of 3.09. The release capacity of short-chain PFAAs was notably higher than that of long-chain PFAAs, and this pattern was further amplified by flow velocity. Pore-water drainage was the major pathway for PFAA release, with the release amount predominantly determined by flow velocity-induced release intensity and depth, as well as affected by the perfluorocarbon chain length and sediment size. The weak anion exchanger-diffusion gradients in the thin-film technique confirmed that the release depth of PFAAs increased with flow velocity. Quadrant analysis revealed that the rise in the frequency and intensity of turbulent bursts driven by sweeps and ejections at high flow velocity was the underlying cause of the increased release magnitude and depth of PFAAs.

Anthropogenic stressors and the marine environment: From sources and impacts to solutions and mitigation

Human-released contaminants are often poorly understood wholistically in marine ecosystems. This review examines the sources, pathways, impacts on marine animals, and mitigation strategies of five pollutants (plastics, per- and polyfluoroalkyl substances, bisphenol compounds, ethynylestradiol, and petroleum hydrocarbons). Both abiotic and biotic mechanisms contribute to all five contaminants' movement. These pollutants cause short- and long-term effects on many biological processes genetically, molecularly, neurologically, physiologically, reproductively, and developmentally. We explore the extension of adverse outcome pathways to ecosystem effects by considering known inter-generational and trophic relations resulting in large-scale direct and indirect impacts. In doing so, we develop an understanding of their roles as environmental stressors in marine environments for targeted mitigation and future work. Ecosystems are interconnected and so international collaboration, standards, measures preceding mass production, and citizen involvement are required to protect and conserve marine life.

Occurrence and profiles of perfluoroalkyl substances in wastewaters of chemical industrial parks and receiving river waters: Implications for the environmental impact of wastewater discharge

A total of 17 groups of wastewaters from the chemical industrial parks and matched receiving river waters were collected in the east of China. The measured total concentrations of 21 analyzed PFAS analogues (∑21PFAS) in the influents and effluents of the wastewater treatment plants (WWTPs) were in the range of 0.172-20.6 μg/L (mean: 18.2 μg/L, median: 3.9 μg/L) and 0.167-93.6 μg/L (mean: 10.8 μg/L, median: 1.12 μg/L), respectively, which were significantly higher than those observed in the upstream (range: 0.0158-7.05 μg/L, mean: 1.09 μg/L, median: 0.482 μg/L) and downstream (range: 0.0237-1.82 μg/L, mean: 0.697 μg/L, median: 0.774 μg/L) receiving waters. Despite the concentrations and composition profiles of PFAS varied in the water samples from different sampling sites, PFOA was generally the major PFAS analogue in the research areas, mainly due to the history of PFOA production and usage as well as the specific exemptions. The calculated concentration ratios of the short-chain PFCAs and PFSAs to their respective predecessors (PFOA and PFOS) in most of the samples far exceeded 1, indicating a shift from legacy PFOA and PFOS to short-chain PFAS in the research areas. Correlation network analysis and the calculated concentration ratios of PFAS in the effluents versus influents indicated transformation may have occurred during the water treatment processes and PFAS could not be efficiently removed in the WWTPs. Wastewater discharge of chemical industrial parks is a vital source of PFAS dispersed into the aquatic environment.

Nontarget Discovery of Per- and Polyfluoroalkyl Sulfonyl Halides in Soils by Integration of Derivatization and Specific Fragment-Based Liquid Chromatography-High Resolution Mass Spectrometry Screening

Though long recognized as synthetic precursors to other poly- and perfluoroalkyl substances (PFASs), most poly- and perfluoroalkyl sulfonyl halides (PASXs) cannot be directly measured and have generally received minimal attention. Inspired by the redox reaction between sulfonyl halide groups and p-toluenethiol in organic chemistry, we developed a novel nontarget analysis strategy for PASXs by intergrating derivatization and specific fragment-based liquid chromatography-high resolution mass spectrometry screening for m/z 82.961 [SO2F-] and m/z 95.934 [S2O2-]. By using this strategy, we discovered 11 PASXs, namely, perfluoroalkyl sulfonyl fluorides (5), polyfluoroalkyl sulfonyl fluorides (2), unsaturated perfluoroalkyl sulfonyl fluoride (1), and perfluoroalkyl sulfonyl chlorides (3) in soil samples collected from an abandoned fluorochemical manufacturing park. These average ∑PASXs concentrations were 1120 μg kg-1 (range: 9.7-9860 μg kg-1), which were very likely to be the key intermediates and undesired byproducts of electrochemical fluorination processes. Spatial variation in the mass ratio of ∑PASXs to ∑PFSAs (range: 0.7-795%) also indicates their different transportation pathways. More importantly, the decline of PASXs and increase of perfluoroalkyl sulfonates (when compared to a prior study at this site) suggest the continued hydrolysis of PASXs and the relatively fast environmental transformation rates in the abandoned fluorochemical park soils. Overall, these findings demonstrated the utility of a novel nontarget analysis strategy, which may change most PASXs from inferred precursors to measured intermediates and further could be adapted for structures, distribution, and transformation studies of PFASXs in other matrices.

Per- and polyfluoroalkyl substances (PFAS) in senior care facilities and older adult residents

Per- and polyfluoroalkyl substances (PFAS) are fluorinated organic compounds used in a variety of consumer products and industrial applications that persist in the environment, bioaccumulate in biological tissues, and can have adverse effects on human health, especially in vulnerable populations. In this study, we focused on PFAS exposures in residents of senior care facilities. To investigate relationships between indoor, personal, and internal PFAS exposures, we analyzed 19 PFAS in matched samples of dust collected from the residents' bedrooms, and wristbands and serum collected from the residents. The median ∑PFAS concentrations (the sum of all PFAS detected in the samples) measured in dust, wristbands, and serum were 120 ng/g, 0.05 ng/g, and 4.0 ng/mL, respectively. The most abundant compounds in serum were linear- and branched-perfluorooctane sulfonic acid (L-PFOS and B-PFOS, respectively) at medians of 1.7 ng/mL and 0.83 ng/mL, respectively, followed by the linear perfluorooctanoic acid (L-PFOA) found at a median concentration of 0.59 ng/mL. Overall, these three PFAS comprised 80 % of the serum ∑PFAS concentrations. A similar pattern was observed in dust with L-PFOS and L-PFOA found as the most abundant PFAS (median concentrations of 13 and 7.8 ng/g, respectively), with the overall contribution of 50 % to the ∑PFAS concentration. Only L-PFOA was found in wristbands at a median concentration of 0.02 ng/g. Significant correlations were found between the concentrations of several PFAS in dust and serum, and in dust and wristbands, suggesting that the indoor environment could be a significant contributor to the personal and internal PFAS exposures in seniors. Our findings demonstrate that residents of assisted living facilities are widely exposed to PFAS, with several PFAS found in blood of each study participant and in the assisted living environment.

External liquid calibration method for iodide chemical ionization mass spectrometry enables quantification of gas-phase per- and polyfluoroalkyl substances (PFAS) dynamics in indoor air

Per- and polyfluoroalkyl substances (PFAS) are manufactured chemicals that have been detected across the globe. Fluorotelomer alcohols (FTOHs) are one PFAS class commonly found in indoor air due to emissions from consumer products (e.g., textiles and food packaging) and are human metabolic, atmospheric oxidative, and industrial precursors of perfluoroalkyl carboxylic acids (PFCAs). We developed a quantitative method for real-time analysis of gas-phase FTOHs, perfluoroalkyl acids (PFCAs and GenX), one perfluorooctane sulfonamide (EtFOSA), one fluorotelomer diol (FTdiOH), and one fluorinated ether (E2) using high-resolution time-of-flight chemical ionization mass spectrometry equipped with iodide reagent ion chemistry (I-HR-ToF-CIMS). Herein, we present a direct liquid injection method for external calibration, providing detection limits of 0.19-3.1 pptv for 3 s averaging and 0.02-0.44 pptv for 120 s averaging, with the exception of E2, which had detection limits of 1700 and 220 pptv for 3- and 120 s averaging, respectively. These calibrations enabled real-time gas-phase quantification of 6 : 2 FTOH in room air while microwaving popcorn, with an average peak air concentration of 31.6 ± 4.5 pptv measured 2 meters from a closed microwave. Additionally, 8 : 2 and 10 : 2 FTOH concentrations in indoor air were measured in the presence and absence of a rain jacket, with observed peak concentrations of 110 and 25 pptv, respectively. Our work demonstrates the ability of I-HR-ToF-CIMS to provide real-time air measurements of PFAS relevant to indoor human exposure settings and allow for PFAS source identification. We expect that real-time quantification of other gas-phase PFAS classes is possible, enabling advances in understanding PFAS sources, chemistry, and partitioning.

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

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

Perfluoroalkyl acid adsorption by styrenic β-cyclodextrin polymers, anion-exchange resins, and activated carbon is inhibited by matrix constituents in different ways

Perfluoroalkyl acids (PFAAs) are ubiquitous environmental contaminants of global concern, and adsorption processes are the most widely used technologies to remove PFAAs from water. However, there remains little data on the ways that specific water matrix constituents inhibit the adsorption of PFAAs on different adsorbents. In this study, we evaluated the adsorption of 13 PFAAs on two styrene-functionalized β-cyclodextrin (StyDex) polymers, an activated carbon (AC), and an anion-exchange resin (AER) in the absence and presence of specific water matrix constituents (16 unique water matrices) in batch experiments. All four adsorbents exhibited some extent of adsorption inhibition in the presence of inorganic ions and/or humic acid (HA) added as a surrogate for natural organic matter. Two PFAAs (C5-C6 perfluorocarboxylic acids (PFCAs)) were found to exhibit relatively weak adsorption and five PFAAs (C6-C8 perfluorosulfonic acids (PFSAs) and C9-C10 PFCAs) were found to exhibit relatively strong adsorption on all four adsorbents across all matrices. Adsorption inhibition was the greatest in the presence of Ca2+ (direct site competition) and HA (direct site competition and pore blockage) for AC, NO3- (direct site competition) and Ca2+ (chemical complexation) for the AER, and SO42- (compression of the double layer) for the StyDex polymers. The pattern of adsorption inhibition of both StyDex polymers were similar to each other but different from AC and AER, which demonstrates the distinctive PFAA adsorption mechanism on StyDex polymers. The unique performance of each type of adsorbent confirms unique adsorption mechanisms that result in unique patterns of adsorption inhibition in the presence of matrix constituents. These insights could be used to develop models to predict the performance of these adsorbents in real water matrices and afford rational selection of adsorbents based on water chemistry for specific applications.

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.

Per-and polyfluoroalkyl (PFAS) eternal pollutants: Sources, environmental impacts and treatment processes

Per- and polyfluoroalkyl substances (PFAS) have become a growing environmental concern due to their tangible impacts on human health. However, due to the large number of PFAS compounds and the analytical difficulty to identify all of them, there are still some knowledge gaps not only on their impact on human health, but also on how to manage them and achieve their effective degradation. PFAS compounds originate from man-made chemicals that are resistant to degradation because of the presence of the strong carbon-fluorine bonds in their chemical structure. This review consists of two parts. In the first part, the environmental effects of fluorinated compound contamination in water are covered with the objective to highlight how their presence in the environment adversely impacts the human health. In the second part, the focus is put on the different techniques available for the degradation and/or separation of PFAS compounds in different types of waters. Examples of removal/treatment of PFAS present in either surface or ground water are presented.

Emerging contaminants in food matrices: An overview of the occurrence, pathways, impacts and detection techniques of per- and polyfluoroalkyl substances

Per- and polyfluoroalkyl substances (PFAS) have been used in industrial and consumer applications for ages. The pervasive and persistent nature of PFAS in the environment is a universal concern due to public health risks. Experts acknowledge that exposure to high levels of certain PFAS have consequences, including reduced vaccine efficacy, elevated cholesterol, and increased risk of high blood pressure. While considerable research has been conducted to investigate the presence of PFAS in the environment, the pathways for human exposure through food and food packaging/contact materials (FCM) remain unclear. In this review, we present an exhaustive overview of dietary exposure pathways to PFAS. Also, the mechanism of PFAS migration from FCMs into food and the occurrence of PFAS in certain foods were considered. Further, we present the analytical techniques for PFAS in food and food matrices as well as exposure pathways and human health impacts. Further, recent regulatory actions working to set standards and guidelines for PFAS in food packaging materials were highlighted. Alternative materials being developed and evaluated for their safety and efficacy in food contact applications, offering promising alternatives to PFAS were also considered. Finally, we reported on general considerations and perspectives presently considered.

Association between per- and poly-fluoroalkyl substances and nonalcoholic fatty liver disease: A nested case-control study in northwest China

Per- and poly-fluoroalkyl substances (PFAS) have been reported to have hepatotoxic effects. However, it is unclear whether they are linked to non-alcoholic fatty liver disease (NAFLD). This nested case-control study focused on the epidemiological links between PFAS and the prevalence of NAFLD. We selected 476 new cases of NAFLD and 952 age- and sex-matched controls from the Jinchang cohort population between 2014 and 2019. Serum concentrations of PFAS were measured using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Only PFAS with a detection rate of ≥90 % were included for analysis, which included PFPeA, PFOA, PFNA, PFHxS, PFOS, and 9Cl-PF3ONS. The relationship between single and co-exposure to PFAS and the occurrence of NAFLD was evaluated using conditional logistic regression, Quantile g-computation (QgC), and Bayesian kernel machine regression (BKMR) model. Logistic regression indicated that PFPeA, PFOA, and 9Cl-PF3ONS were positive correlation with the incidence of NAFLD after adjusting for confounders, with odds ratios (OR) and 95 % confidence interval (CI) of 3.13 (95 % CI: 2.53, 3.86), 1.39 (95 % CI: 1.12, 1.73), and 1.41 (95 % CI: 1.20, 1.66), respectively. PFNA, PFHxS, and PFOS were nonlinearly and negatively associated with the incidence of NAFLD, with OR (95 % CI) of 0.53 (0.46, 0.62), 0.83 (0.73, 0.95), and 0.52 (0.44, 0.61), respectively. QgC showed a significant joint effect of PFAS mixture on NAFLD onset (OR: 1.52, 95 % CI: 1.24, 1.88). BKMR showed a weak positive trend between PFAS mixtures and NAFLD incidence. Positive correlations were primarily driven by PFPeA and 9Cl-PF3ONS, while negative correlations were mainly influenced by PFNA and PFOS. The BKMR model also suggested that there was an interaction between PFOS and PFNA and other four PFAS compounds. In conclusion, our findings suggest that individual and co-exposure to PFAS is associated with a risk of NAFLD onset.

Perfluorobutanoic acid triggers metabolic and transcriptional reprogramming in wheat seedlings

The environmental risks of fluorinated alternatives are of great concern with the phasing out of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate. Here, multi-omics (i.e., metabolomics and transcriptomics) coupled with physiological and biochemical analyses were employed to investigate the stress responses of wheat seedings (Triticum aestivum L.) to perfluorobutanoic acid (PFBA), one of the short-chain per- and polyfluoroalkyl substances (PFAS) and PFOA alternatives, at environmentally relevant concentrations (0.1-100 ng/g). After 28 days of soil exposure, PFBA boosted the generation of OH and O2- in wheat seedlings, resulting in lipid peroxidation, protein perturbation and impaired photosynthesis. Non-enzymatic antioxidant defense systems (e.g., glutathione, phenolics, and vitamin C) and enzymatic antioxidant copper/zinc superoxide dismutase were strikingly activated (p < 0.05). PFBA-triggered oxidative stress induced metabolic and transcriptional reprogramming, including carbon and nitrogen metabolisms, lipid metabolisms, immune responses, signal transduction processes, and antioxidant defense-related pathways. Down-regulation of genes related to plant-pathogen interaction suggested suppression of the immune-response, offering a novel understanding on the production of reactive oxygen species in plants under the exposure to PFAS. The identified MAPK signaling pathway illuminated a novel signal transduction mechanism in plant cells in response to PFAS. These findings provide comprehensive understandings on the phytotoxicity of PFBA to wheat seedlings and new insights into the impacts of PFAS on plants.

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

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

Global quantification of emerging and legacy per- and polyfluoroalkyl substances in indoor dust: Levels, profiles and human exposure

This study investigated the occurrence and distribution of per- and polyfluoroalkyl substances (PFASs) in house dust samples from six regions across four continents. PFASs were detected in all indoor dust samples, with total median concentrations ranging from 17.3 to 197 ng/g. Among the thirty-one PFAS analytes, eight compounds, including emerging PFASs, exhibited high detection frequencies in house dust from all six locations. The levels of PFASs varied by region, with higher concentrations found in Adelaide (Australia), Tianjin (China), and Carbondale (United States, U.S.). Moreover, PFAS composition profiles also differed among regions. Dust from Australia and the U.S. contained high levels of 6:2 fluorotelomer phosphate ester (6:2 diPAP), while perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) were predominant in other regions. Furthermore, our results indicate that socioeconomic factors impact PFAS levels. The assessment of human exposure through dust ingestion and dermal contact indicates that toddlers may experience higher exposure levels than adults. However, the hazard quotients of PFASs for both toddlers and adults were below one, indicating significant health risks are unlikely. Our study highlights the widespread occurrence of PFASs in global indoor dust and the need for continued monitoring and regulation of these chemicals.

Total and Class-Specific Determination of Fluorinated Compounds in Consumer and Food Packaging Samples Using Fluorine-19 Solid-State Nuclear Magnetic Resonance Spectroscopy

Hamburger wrapping paper, coated with water-based barrier coatings, used in the food packaging industry was studied by using the total organic fluorine (TOF) method based on combustion ion chromatography and fluorine-19 solid-state nuclear magnetic resonance (19F ss-NMR) spectroscopy. Although the TOF method is a fast and affordable method used to screen for per- and polyfluoroalkyl substances (PFAS), the amount of fluorine it measures is heavily dependent on the extraction step and, therefore could lead to inaccurate results. Fluorine-19 ss-NMR spectroscopy can differentiate between organic and inorganic fluorinated sources, eliminating the need for sample clean up. To illustrate this, the 19F ss-NMR spectra of clean coated paper samples that contained naturally occurring F- ions from the talc raw material and spiked samples containing perfluorooctanoic acid were compared. A range of experimental conditions was explored to improve sensitivity for low PFAS concentrations (in the order of 10-20 mg/kg). Despite the disadvantages of ss-NMR spectroscopy, such as the low limit of detection and resolution, the results demonstrate it can be a viable tool to directly detect PFAS moieties in consumer and food packaging. Therefore, 19F solid-state NMR spectroscopy challenges and complements current methods, which only provide indirect evidence of the presence of PFAS.

Occurrence and Fate of Per- and Polyfluoroalkyl Substances (PFAS) in Atmosphere: Size-Dependent Gas-Particle Partitioning, Precipitation Scavenging, and Amplification

The concerns about the fate of per- and polyfluoroalkyl substances (PFAS) in the atmosphere are continuously growing. In this study, size-fractionated particles, gas, and rainwater samples were simultaneously collected in Shijiazhuang, China, to investigate the multiphase distribution of PFAS in the atmosphere. Perfluoroalkyl carboxylic acids (PFCAs) dominated the total concentration of PFAS in atmospheric media. A strong positive relationship (0.79 < R2 < 0.99) was observed between the concentration of PFCAs and organic matter fraction (fOM) in different particle size fractions, while no such relationship for perfluoroalkyl sulfonic acids (PFSAs) and fOM, suggesting fOM may be an important factor influencing the size-dependent distribution of PFCAs. Temperature played a key role in the gas-particle partitioning of PFAS, while it did not significantly affect their particle-size-dependent distribution. The associative concentration fluctuation of particle and particle-bound PFAS during precipitation suggested that precipitation scavenging was an important mechanism for the removal of PFAS from the atmosphere. Furthermore, temporary increases in atmospheric PFAS concentrations were observed during the precipitation. Fugacity ratios of PFAS in rainwater and gas phase (log fR/fG ranged between 2.0 and 6.6) indicated a strong trend for PFAS to diffuse from the rainwater to the gas phase during the precipitation, which may explain that the concentration of PFAS in the gas phase continued to increase even at the end of the precipitation.

Groundwater solutes influence the adsorption of short-chain perfluoroalkyl acids (PFAA) to colloidal activated carbon and impact performance for in situ groundwater remediation

Subsurface injection of colloidal activated carbon (CAC) is an in situ remediation strategy for perfluoroalkyl acids (PFAA), but the influence of groundwater solutes on longevity is uncertain, particularly for short-chain PFAA. We quantify the impact of inorganic anions, dissolved organic matter (DOM), and stabilizing polymer on PFAA adsorption to a commercial CAC. Surface characterization supported PFAA chain-length dependent adsorption results and mechanisms are provided. Inorganic anions decreased adsorption for short-chain PFAA (<7 perfluorinated carbons) due to competitive effects, while long-chain PFAA (≥ 7 perfluorinated carbons) were less impacted. DOM decreased adsorption of all PFAA in a chain-length dependent manner. High DOM concentrations (10 mg/L, ∼5 mg OC/L) decreased PFOA adsorption by a factor of 2, PFPeA by one order of magnitude, and completely hindered PFBA adsorption. High MW DOM has less impact on short-chain PFAA than low MW DOM, possibly due to differences in the ability to access CAC micropores. Low DOM concentrations (1 mg/L, ∼0.5 mg OC/L) did not impact adsorption. CMC (90 kDa average MW) had negligible impact on PFAA adsorption likely due to minimal CAC surface coverage. Longevity modeling demonstrated that groundwater solutes limit the capacity for PFAA in a CAC barrier, particularly for short-chain PFAA.

Multi-omics reveals the molecular mechanism of the combined toxic effects of PFOA and 4-HBP exposure in MCF-7 cells and the key player: mTORC1

With the discovery of evidence that many endocrine-disrupting chemicals (EDCs) in the environment influence human health, their toxic effects and mechanisms have become a hot topic of research. However, investigations into their endocrine-disrupting toxicity under combined binary exposure, especially the molecular mechanism of combined effects, have rarely been documented. In this study, two typical EDCs, perfluorooctanoic acid (PFOA) and 4-hydroxybenzophenone (4-HBP), were selected to examine their combined effects and molecular mechanism on MCF-7 cell proliferation at environmentally relevant exposure concentrations. We have successfully established a model to evaluate the binary combined toxic effects of endocrine disruptors, presenting combined effects in a simple and direct way. Results indicated that the combined effect changed from additive to synergistic from 1.25 × 10-8 M to 4 × 10-7 M. Metabolomics analyses suggested that exposure to PFOA and 4-HBP caused significant alterations in purine metabolism, arginine, and proline metabolism and had superimposed influences on metabolism. Enhanced combined effects were observed in glycine, serine, and threonine metabolic pathways compared to exposure to PFOS and 4-HBP alone. Additionally, the differentially expressed genes (DEGs) are primarily involved in Biological Processes, especially protein targeting the endoplasmic reticulum, and significantly impact the oxidative phosphorylation and thermogenesis-related KEGG pathway. By integrating metabolome and transcriptome analyses, PFOA and 4-HBP regulate purine metabolism, the TCA cycle, and endoplasmic reticulum protein synthesis in MCF-7 cells via mTORC1, which provides genetic material, protein, and energy for cell proliferation. Furthermore, molecular docking confirmed the ability of PFOA and 4-HBP to stably bind the estrogen receptor, indicating that they have different binding pockets. Collectively, these findings will offer new insights into understanding the mechanisms by which EDCs produce combined toxicity.

Grouping strategies for assessing and managing persistent and mobile substances

Background

Persistent, mobile and toxic (PMT), or very persistent and very mobile (vPvM) substances are a wide class of chemicals that are recalcitrant to degradation, easily transported, and potentially harmful to humans and the environment. Due to their persistence and mobility, these substances are often widespread in the environment once emitted, particularly in water resources, causing increased challenges during water treatment processes. Some PMT/vPvM substances such as GenX and perfluorobutane sulfonic acid have been identified as substances of very high concern (SVHCs) under the European Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) regulation. With hundreds to thousands of potential PMT/vPvM substances yet to be assessed and managed, effective and efficient approaches that avoid a case-by-case assessment and prevent regrettable substitution are necessary to achieve the European Union's zero-pollution goal for a non-toxic environment by 2050.

Main

Substance grouping has helped global regulation of some highly hazardous chemicals, e.g., through the Montreal Protocol and the Stockholm Convention. This article explores the potential of grouping strategies for identifying, assessing and managing PMT/vPvM substances. The aim is to facilitate early identification of lesser-known or new substances that potentially meet PMT/vPvM criteria, prompt additional testing, avoid regrettable use or substitution, and integrate into existing risk management strategies. Thus, this article provides an overview of PMT/vPvM substances and reviews the definition of PMT/vPvM criteria and various lists of PMT/vPvM substances available. It covers the current definition of groups, compares the use of substance grouping for hazard assessment and regulation, and discusses the advantages and disadvantages of grouping substances for regulation. The article then explores strategies for grouping PMT/vPvM substances, including read-across, structural similarity and commonly retained moieties, as well as the potential application of these strategies using cheminformatics to predict P, M and T properties for selected examples.

Conclusions

Effective substance grouping can accelerate the assessment and management of PMT/vPvM substances, especially for substances that lack information. Advances to read-across methods and cheminformatics tools are needed to support efficient and effective chemical management, preventing broad entry of hazardous chemicals into the global market and favouring safer and more sustainable alternatives.

Chemical mixture effects on the simplified human intestinal microbiota: Assessing xenobiotics at environmentally realistic concentrations

The microbial community present in our intestines is pivotal for converting indigestible substances into vital nutrients and signaling molecules such as short-chain fatty acids (SCFAs). These compounds have considerable influence over our immune system and the development of diverse human diseases. However, ingested environmental contaminants, known as xenobiotics, can upset the delicate balance of the microbial gut community and enzymatic processes, consequently affecting the host organism. In our study, we employed an in vitro bioreactor model system based on the simplified human microbiome model (SIHUMIx) to investigate the direct effects of specific xenobiotics, such as perfluorooctanoic acid (PFOA), perfluorohexanoic acid (PFHxA) and perfluorobutanoic acid (PFBA) or bisphenol S (BPS) and bisphenol F (BPF), either individually or in combination, on the microbiota. We observed increased SCFA production, particularly acetate and butyrate, with PFAS exposure. Metaproteomics revealed pathway alterations across treatments, including changes in vitamin synthesis and fatty acid metabolism with BPX. This study underscores the necessity of assessing the combined effects of xenobiotics to better safeguard public health. It emphasizes the significance of considering adverse effects on the microbiome in the risk assessment of environmental chemicals.

Considerations and challenges in support of science and communication of fish consumption advisories for per- and polyfluoroalkyl substances

Federal, state, tribal, or local entities in the United States issue fish consumption advisories (FCAs) as guidance for safer consumption of locally caught fish containing contaminants. Fish consumption advisories have been developed for commonly detected compounds such as mercury and polychlorinated biphenyls. The existing national guidance does not specifically address the unique challenges associated with bioaccumulation and consumption risk related to per- and polyfluoroalkyl substances (PFAS). As a result, several states have derived their own PFAS-related consumption guidelines, many of which focus on one frequently detected PFAS, known as perfluorooctane sulfonic acid (PFOS). However, there can be significant variation between tissue concentrations or trigger concentrations (TCs) of PFOS that support the individual state-issued FCAs. This variation in TCs can create challenges for risk assessors and risk communicators in their efforts to protect public health. The objective of this article is to review existing challenges, knowledge gaps, and needs related to issuing PFAS-related FCAs and to provide key considerations for the development of protective fish consumption guidance. The current state of the science and variability in FCA derivation, considerations for sampling and analytical methodologies, risk management, risk communication, and policy challenges are discussed. How to best address PFAS mixtures in the development of FCAs, in risk assessment, and establishment of effect thresholds remains a major challenge, as well as a source of uncertainty and scrutiny. This includes developments better elucidating toxicity factors, exposures to PFAS mixtures, community fish consumption behaviors, and evolving technology and analytical instrumentation, methods, and the associated detection limits. Given the evolving science and public interests informing PFAS-related FCAs, continued review and revision of FCA approaches and best practices are vital. Nonetheless, consistent, widely applicable, PFAS-specific approaches informing methods, critical concentration thresholds, and priority compounds may assist practitioners in PFAS-related FCA development and possibly reduce variability between states and jurisdictions. Integr Environ Assess Manag 2024;00:1-20. © 2024 SETAC.

Sediment-seawater partitioning, bioaccumulation, and biomagnification of perfluorobutane sulfonamide in marine environment

Environmental occurrence of perfluorobutane sulfonamide (PFBSA) has only been recently discovered. The current knowledge regarding the occurrence and environmental behaviors of PFBSA in the marine environment is still relatively limited. In this study, PFBSA and other 37 poly- and perfluoroalkyl substances were analyzed in seawater (n = 43), sediment (n = 43), and marine fish (n = 176) samples collected from East China Sea and Antarctic Ocean. PFBSA was detected in > 90% of seawater from East China Sea and Antarctic Ocean, with the concentrations of 1.0 - 19 ng/L and < LOD-228 pg/L, respectively. The field-based mean log-transformed sediment-seawater partitioning coefficients of PFBSA were 1.6 ± 0.19 L/kg dw and 1.1 ± 0.19 L/kg dw in East China Sea and Antarctic Ocean, respectively, which are lower than that of perfluorooctanoate and perfluorooctane sulfonate. This indicates its long-range transport potential in global oceans with ocean currents. The mean log-transformed bioaccumulation factor values of PFBSA determined in the multiple species of whole-body marine fishes from East China Sea and Antarctic Ocean were 2.3 L/kg ww and 2.4 L/kg ww, respectively, which are comparable to that of perfluoroheptanoate (2.3 L/kg ww) in marine fishes from East China Sea. We did not observe an obvious biomagnification or biodilution of PFBSA along the marine food chain in East China Sea or Antarctic Ocean. This study provides the first data on the environmental behaviors of PFBSA in the marine environment.

Prenatal exposure to poly/perfluoroalkyl substances and risk for congenital heart disease in offspring

Congenital heart disease (CHD) is the most prevalent congenital malformation worldwide, and the association between per- and polyfluoroalkyl substances (PFASs) exposure and CHD in population has only received limited study. Therefore, we conducted a multicenter case-control study to explore the associations between prenatal exposure to individual PFASs, and also a PFAS mixture, and CHD risk, including 185 CHDs and 247 controls in China from 2016 to 2021. Thirteen PFASs in maternal plasma were quantified using liquid chromatography-tandem mass spectrometry. Logistic regression and two multipollutant models (Bayesian kernel machine regression [BKMR] and quantile g-computation [qgcomp]) were used to assess the potential associations between any individual PFAS, and also a PFAS mixture, and CHD risk. After adjusting for potential confounders, logistic regression indicated significant associations between elevated levels of perfluorononanoic acid (odds ratio [OR]= 1.30, 95% confidence intervals [CI]: 1.07-1.58), perfluorodecanoic acid (OR=2.07, 95%CI: 1.32-3.26), and perfluoroundecanoic acid (OR=2.86, 95%CI:1.45-5.65) and CHD risk. The BKMR model and qgcomp approach identified that a significant positive association between the PFAS mixture and risk for CHD. These findings provide essential evidence that there is indeed a health crisis associated with PFASs and that it is linked to CHD.

Prenatal PFAS exposure, gut microbiota dysbiosis, and neurobehavioral development in childhood

Studies on the role of the gut microbiota in the associations between per- and polyfluoroalkyl substance (PFAS) exposure and adverse neurodevelopment are limited. Umbilical cord serum and faeces samples were collected from children, and the Strengths and Difficulties Questionnaire (SDQ) was conducted. Generalized linear models, linear mixed-effects models, multivariate analysis by linear models and microbiome regression-based kernel association tests were used to evaluate the associations among PFAS exposure, the gut microbiota, and neurobehavioural development. Perfluorohexane sulfonic acid (PFHxS) exposure was associated with increased scores for conduct problems and externalizing problems, as well as altered gut microbiota alpha and beta diversity. PFHxS concentrations were associated with higher relative abundances of Enterococcus spp. but lower relative abundances of several short-chain fatty acid-producing genera (e.g., Ruminococcus gauvreauii group spp.). PFHxS exposure was also associated with increased oxidative phosphorylation. Alpha and beta diversity were found significantly associated with conduct problems and externalizing problems. Ruminococcus gauvreauii group spp. abundance was positively correlated with prosocial behavior scores. Increased alpha diversity played a mediating role in the associations of PFHxS exposure with conduct problems. Our results suggest that the gut microbiota might play an important role in PFAS neurotoxicity, which may have implications for PFAS control.

Associations between per- and polyfluoroalkyl chemicals and abdominal aortic calcification in middle-aged and older adults

INTRODUCTION

Per- and polyfluoroalkyl substances (PFAS) have infiltrated countless everyday products, raising concerns about potential effects on human health, specifically on the cardiovascular system and the development of abdominal aortic calcification (AAC). However, our understanding of this relationship is still limited.

OBJECTIVES

This study aims to investigate the effects of PFAS on AAC using machine learning algorithms.

METHODS

Leveraging the power of machine learning technique, extreme gradient boosting (XGBoost), we assessed the relationship between PFAS exposure and AAC risk. We focused on three PFAS compounds, perfluorodecanoic acid (PFDeA), perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA) through multiple logistic regression, restricted cubic spline (RCS), and quantile g-computation (QGC) models. To get more insight into the underlying mechanisms, mediation analyses are used to investigate the potential mediating role of fatty acids and blood cell fractions in AAC.

RESULTS

Our findings indicate that elevated serum levels of PFHxS and PFDeA are associated with the increased risk of AAC. The QGC analyses underscore the overall positive association between the PFAS mixture and AAC risk, with PFHxS carrying the greatest weight, followed by PFDeA. The RCS analyses reveal a dose-dependent increase between serum PFHxS concentration and AAC risk in an inverted V-shape way. Moreover, age and PFHxS exposure are identified as the primary factors contributing to abdominal aortic calcification risk in SHapley Additive exPlanation (SHAP) summary plot combined with XGBoost technique. Although PFAS significantly change the profile of fatty acids, we do not find any mediating roles of them in AAC. Despite strong associations between PFAS exposure and hematological indicators, our analysis does not find evidence that these indicators mediate the development of AAC.

CONCLUSIONS

In summary, our study highlights the detrimental impact of PFAS on abdominal aortic health and emphasizes the need for further research to understand the underlying mechanisms involved.

Investigating the progression of preeclampsia through a comprehensive analysis of genes associated with per- and polyfluoroalkyl substances

Per- and Polyfluoroalkyl Substances (PFAS) are synthetic chemicals utilized in the production of various products that possess water and dirt-repellent properties. Exposure to PFAS has been linked to numerous diseases, such as cancer and preeclampsia (PE). However, whether PFAS contributes to the advancement of PE remains uncertain. In this study, we conducted an extensive bioinformatics analysis using the Comparative Toxicogenomics Database (CTD) and Gene Expression Omnibus (GEO) databases, leading us to discover a connection between PE and four specific PFAS. Moreover, further examination revealed that six genes associated with PFAS exhibited significant diagnostic potential for individuals with PE. By employing receiver operating characteristic (ROC) curves, our PFAS-related gene-based nomogram model demonstrated outstanding predictive efficacy for diagnosing PE. Immune infiltration analysis showed that six PFAS-related genes were significantly associated with the level of immune cell infiltration. The expression of PFAS-related genes in PE patients was confirmed by collecting clinical samples. This research has offered fresh perspectives on comprehending the impact of PFAS on PE, drawing attention to the connection between environmental factors and the risks and development of PE.

Exploring Negative Chemical Ionization of Per- and Polyfluoroalkyl Substances via a Liquid Electron Ionization LC-MS Interface

Per- and polyfluoroalkyl substances (PFASs) are a class of aliphatic manufactured compounds comprising fluoro-chemicals with varied functional groups and stable carbon-fluorine bonds. They are defined as "forever chemicals" due to their persistent and bioaccumulative character. These substances have been detected in various environmental samples, including water, air, soil, and human blood, posing significant health hazards. High-performance liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC-ESI-MS) is typically employed for the analysis of PFASs. Negative chemical ionization (NCI) is generally coupled to gas chromatography (GC) and offers high selectivity and sensitivity for compounds containing electronegative atoms, such as PFASs. The liquid electron ionization (LEI) interface is an efficient mechanism developed to robustly couple a liquid flow rate from an LC system to an EI or a CI source. This interface has been successfully utilized for pesticide determination in UHPLC-LEI-CI in negative ion mode (NCI). This work aims to evaluate different parameters involved in the ionization of PFASs analyzed in LC-LEI-NCI and subsequently develop a method for their detection in real samples. The parameters considered for this study include (i) a comparison of different CI reagent gases (methane, isobutane, and argon); (ii) the use of acetonitrile as both the chromatographic solvent and CI reagent gas; (iii) the presence of water and formic acid as chromatographic mobile phase components; and (iv) the mobile phase flow rate. The optimal combination of these parameters led to promising results. Tentative fragmentation pathways of PFASs in NCI mode are proposed based on the dissociative electron capture mechanism.

Perfluoroalkyl substances (PFAS) occurrence, concentrations and spatial distribution along the French Mediterranean coast and lagoons, based on active biomonitoring

Tracking PFAS in ecosystems is challenging. In this context, monitoring programs are crucial to fill data gaps, especially in marine environments, which are the ultimate outlets for these forever chemicals. The 2021 chemical contamination monitoring campaign along the French Mediterranean coast established a baseline for PFAS concentrations in mussels, with 90 % of measurements below quantification limits. When detected, long-chain PFCA's were predominant. Spatial distribution patterns suggested continuous PFAS inputs and complex dynamics, shaped by the influence of large watersheds and rivers (Rhône, Aude, Huveaune). Lapeyrade shallow lagoon stood out as the most contaminated site. Similar PFAS profiles in connected sites implied shared sources but raised questions about accumulation processes in mussels. While certain sites had evident sources (e.g., military airbase for Palo lagoon), others remained uncertain (e.g., Toulon bay). Coastal stations (Banyuls, Cap Agde, Brégançon, Pampelonne) showed PFAS contamination without clear onshore sources, possibly due to insufficient transportation process understanding.

Evaluation of per- and polyfluoroalkyl substances (PFAS) in landfill liquids from Pennsylvania, Colorado, and Wisconsin

PER: and polyfluoroalkyl substances (PFAS) have been measured in aqueous components within landfills. To date, the majority of these studies have been conducted in Florida. This current study aimed to evaluate PFAS concentrations in aqueous components (leachate, gas condensate, stormwater, and groundwater) from four landfills located outside of Florida, in Pennsylvania, Colorado, and Wisconsin (2 landfills). The Pennsylvania landfill also provided the opportunity to assess a leachate treatment system. Sample analyses were consistent across studies including the measurements of 26 PFAS and physical-chemical parameters. For the four target landfills, average PFAS concentrations were 6,900, 22,000, 280, and 260 ng L-1 in the leachate, gas condensate, stormwater, and groundwater, respectively. These results were not significantly different than those observed for landfills in Florida except for the significantly higher PFAS concentrations in gas condensate compared to leachate. For on-site treatment at the Pennsylvania landfill, results suggest that the membrane biological bioreactor (MBBR) system performed similarly as aeration-based leachate treatment systems at Florida landfills resulting in no significant decreases in ∑26PFAS. Overall, results suggest a general consistency across US regions in PFAS concentrations within different landfill liquid types, with the few differences observed likely influenced by landfill design and local climate. Results confirm that leachate exposed to open air (e.g., in trenches or in treatment systems) have lower proportions of perfluoroalkyl acid precursors relative to leachate collected in enclosed pipe systems. Results also confirm that landfills without bottom liner systems may have relatively higher PFAS levels in adjacent groundwater and that landfills in wetter climates tend to have higher PFAS concentrations in leachate.

Perfluorotetradecanoic acid exposure to adult male rats stimulates corticosterone biosynthesis but inhibits aldosterone production

Perfluorotetradecanoic acid (PFTeDA) is a novel perfluoroalkyl substance that ubiquitously exists in the environment. However, whether PFTeDA affects adrenal cortex function remains unclear. Male Sprague-Dawley rats (age of 60 days) were daily administered with PFTeDA (0, 1, 5, and 10 mg/kg body weight) through gavage for 28 days. PFTeDA did not change body and adrenal gland weights. PFTeDA markedly elevated serum corticosterone level at 10 mg/kg but lowering serum aldosterone level at this dosage without influencing serum adrenocorticotropic hormone level. PFTeDA thickened zona fasciculata without affecting zona glomerulosa. PFTeDA remarkably upregulated the expression of corticosterone biosynthetic genes (Mc2r, Scarb1, Star, Cyp21, Cyp11b1, and Hsd11b1) and their proteins, whereas downregulating aldosterone biosynthetic enzyme Cyp11b2 and its protein, thereby distinctly altering their serum levels. PFTeDA markedly downregulated the expression of antioxidant genes (Sod1 and Sod2) and their proteins at 10 mg/kg. PFTeDA significantly decreased SIRT1/PGC1α and AMPK signaling while stimulating AKT1/mTOR signaling. Corticosterone significantly inhibited testosterone production by adult Leydig cells at >0.1 μM in vitro; however aldosterone significantly stimulated testosterone production at 0.1 nM. In conclusion, exposure to PFTeDA at male rat adulthood causes corticosterone excess and aldosterone deficiency via SIRT1/PGC1α, AMPK, and AKT1/mTOR signals, which in turn additively leads to testosterone deficiency.

Effects on food intake of Gammarus spp. after exposure to PFBA in very low concentrations

Per- and polyfluoroalkyl substances (PFAS) are a group of thousands of highly persistent anthropogenic chemicals widely used in many industries. Therefore, they are, ubiquitously present in various types of environments. Despite their omnipresence, ecotoxicological studies of most PFAS are scarce, and those available often assess the effects of long chain PFAS. In this study, we present the results of an exposure experiment in which wild aquatic amphipod Gammarus spp. was exposed to the short chain perfluorinated substance perfluorobutanoic acid (PFBA) at very low and environmentally relevant concentrations of 0, 10 and 100 ng/L. The exposure lasted for 12 days, and food intake and non-reproductive behavior were analyzed. Exposure to 10 and 100 ng/L PFBA resulted in a lower consumption of food during exposure but no effect on behavior was found.

New insights into the mechanism and kinetics of the addition reaction of unsaturated Criegee intermediates to CF3COOH and tropospheric implications

In this work, we have investigated the mechanism, thermochemistry and kinetics of the reaction of syn-cis-CH2RzCRyCO+O- (where Rz, Ry = H, CH3-) unsaturated Criegee intermediates (CIs) with CF3COOH using quantum chemical methods. The rate coefficients for the barrierless reactions were calculated using variable reaction coordinate variational transition state theory (VRC-VTST). For the syn-cis-CH2RzCRyCO+O- conformation in which conjugated CC and CO double bonds are aligned with each other, we propose a new pathway for the unidirectional addition of an OC-OH molecule (CF3COOH) to the CC double bond of syn-cis-CH2RzCRyCO+O-. The rate coefficient for the 1,4-CC addition reaction at 298 K is ∼10-10 to 10-11 cm3 s-1, resulting in the formation of CF3C(O)OCH2CRzRyCOOH trifluoroacetate alkyl allyl hydroperoxide (TFAAAH) as a new transitory adduct. It can act as a precursor for the formation of secondary organic aerosols (SOAs). This novel TFAAAH hydroperoxide was identified through a detailed quantum chemical study of the 1,4-addition mechanism and will provide new insights into the significance of the 1,4-addition reaction of unsaturated Cls with trace tropospheric gases on -CRzCH2 vinyl carbon atoms.

Prioritization and Risk Ranking of Regulated and Unregulated Chemicals in US Drinking Water

Drinking water constituents were compared using more than six million measurements (USEPA data) to prioritize and risk-rank regulated and unregulated chemicals and classes of chemicals. Hazard indexes were utilized for hazard- and risk-based chemicals, along with observed (nondetects = 0) and censored (nondetects = method detection limit/2) data methods. Chemicals (n = 139) were risk-ranked based on population exposed, resulting in the highest rankings for inorganic compounds (IOCs) and disinfection byproducts (DBPs), followed by semivolatile organic compounds (SOCs), nonvolatile organic compounds (NVOCs), and volatile organic compounds (VOCs) for observed data. The top 50 risk-ranked chemicals included 15 that were unregulated, with at least one chemical from each chemical class (chromium-6 [#1, IOC], chlorate and NDMA [#11 and 12, DBP], 1,4-dioxane [#25, SOC], PFOS, PFOA, PFHxS [#42, 44, and 49, NVOC], and 1,2,3-trichloropropane [#48, VOC]). These results suggest that numerous unregulated chemicals are of higher exposure risk or hazard in US drinking water than many regulated chemicals. These methods could be applied following each Unregulated Contaminant Monitoring Rule (UCMR) data collection phase and compared to retrospective data that highlight what chemicals potentially pose the highest exposure risk or hazard among US drinking water, which could inform regulators, utilities, and researchers alike.

Environmental occurrence, bioaccumulation and human risks of emerging fluoroalkylether substances: Insight into security of alternatives

Per- and polyfluoroalkyl substances (PFASs) are widely used due to their unique structure and excellent performance, while also posing threats on ecosystem, especially long-chain perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). As the control of conventional PFASs, fluoroalkylether substances (ether-PFASs) as alternatives are constantly emerging. Subsequently, the three representative ether-PFASs, chlorinated polyfluoroalkyl ether sulfonic acid (F-53B), hexafluoropropylene oxide-dimer acid (HFPO-DA), and 4,8-Dioxa-3H-perfluorononanoicacid (ADONA) are discovered and have received more attention in the environment and ecosystem. But their security is now also being challenged. This review systematically assesses their security from six dimensions including environmental occurrence in water, soil and atmosphere, as well as bioaccumulation and risk in plants, animals and humans. High substitution level is observed for F-53B, whether in environment or living things. Like PFOS or even more extreme, F-53B exhibits high biomagnification ability, transmission efficiency from maternal to infant, and various biological toxicity effects. HFPO-DA still has a relatively low substitution level for PFOA, but its use has emerged in Europe. Although it is less detected in human bodies and has a higher metabolic rate than PFOA, the strong migration ability of HFPO-DA in plants may pose dietary safety concerns for humans. Research on ADONA is limited, and currently, it is detected in Germany frequently while remaining at trace levels globally. Evidently, F-53B has shown increasing risk both in occurrence and toxicity compared to PFOS, and HFPO-DA is relatively safe based on available data. There are still knowledge gaps on security of alternatives that need to be addressed.

Relationship between crustacean consumption and serum perfluoroalkyl substances (PFAS): the Korean National Environmental Health Survey (KoNEHS) cycle 4

Background

Perfluoroalkyl substances (PFASs) are non-aromatic organic compounds, whose hydrogen atoms in the carbon chain substituted by fluorine atoms. PFASs exhibit developmental toxicity, carcinogenicity, hepatotoxicity, reproductive toxicity, immunotoxicity, and hormone toxicity. PFASs are used in the production of disposable food packages, aircraft and automobile devices, cooking utensils, outdoor gear, furniture and carpets, aqueous film forming foam (AFFF), cables and wires, electronics, and semiconductors. This study aimed to determine the association between crustacean consumption and serum PFASs.

Methods

Adult participants (2,993) aged ≥ 19 years were extracted from the 4th cycle data of the Korean National Environmental Health Survey (KoNEHS). Based on the 50th percentile concentrations of serum PFASs, participants were divided into the low-concentration group (LC) and the high-concentration group (HC). General characteristics, dietary factors, coated product usage, and personal care product usage, an independent t-test and χ2 test were analyzed. The odds ratio (OR) of serum PFAS concentration against crustacean consumption was estimated via logistic regression analysis adjusting for general characteristics, dietary factors, coated product usage, and personal care product usage.

Results

The OR for the HC of serum PFASs was higher in individuals with ≥once a week crustacean consumption than in those with < once a week crustacean consumption. Estimated ORs were perfluorohexanesulfonic acid 2.15 (95% confidence interval [CI]: 1.53-3.02), perfluorononanoic acid (PFNA) 1.23 (95% CI: 1.07-1.41), and perfluorodecanoic acid (PFDeA) 1.42 (95% CI: 1.17-1.74) in males, and perfluorooctanoic acid 1.48 (95% CI: 1.19-1.84), perfluorooctanesulfonic acid 1.39 (95% CI: 1.27-1.52), PFNA 1.70 (95% CI: 1.29-2.26) and PFDeA 1.43 (95% CI: 1.32-1.54) in females.

Conclusions

This study revealed the association between the crustacean consumption and concentrations of serum PFASs in general Korean population.

Threats of per- and poly-fluoroalkyl pollutants to susceptible populations

Environmental exposure to per- and poly-fluoroalkyl substances (PFAS) has raised significant global health concerns due to potential hazards in healthy adults. However, the impact of PFAS on susceptible populations, including pregnant individuals, newborns, the older people, and those with underlying health conditions, has been overlooked. These susceptible groups often have physiological changes that make them less resilient to the same exposures. Consequently, there is an urgent need for a comprehensive understanding of the health risks posed by PFAS exposure to these populations. In this review, we delve into the potential health risks of PFAS exposure in these susceptible populations. Equally important, we also examine and discuss the molecular mechanisms that underlie this susceptibility. These mechanisms include the induction of oxidative stress, disruption of the immune system, impairment of cellular metabolism, and alterations in gut microbiota, all of which contribute to the enhanced toxicity of PFAS in susceptible populations. Finally, we address the primary research challenges and unresolved issues that require further investigation. This discussion aims to foster research for a better understanding of how PFAS affect susceptible populations and to pave the way for strategies to minimize their adverse effects.

Effect of liver cancer on the accumulation and hepatobiliary transport of per- and polyfluoroalkyl substances

In this study, we examined the distribution of per- and polyfluoroalkyl substances (PFASs) in liver and bile tissues from the patients with liver cancer (n = 202) and healthy controls (n = 30), and calculated the hepatobiliary transport efficiency (TB-L) of PFASs. Among 21 PFASs, 13 PFASs were frequently detected in the liver (median: 8.80-16.3 ng/g) and bile (median: 11.03-14.26 ng/mL) samples. PFAS concentrations in liver were positively correlated with age, with higher levels of PFASs in the older. Variance analysis showed that gender and BMI (Body Mass Index) have an important impact on the distribution of PFASs. A U-shaped trend in TB-L of PFASs with the increasing of carbon chain length was found for the first time, and the TB-L of most PFASs in the control was higher than that of those in cases (p < 0.05), suggesting that hepatic injury would affect their transport. PFASs were positively associated with liver injury biomarkers, including γ-glutamyl transferase (GGT), alanine aminotransferase (ALT), and total bilirubin (TB) levels (p < 0.05). This is the first study on examining the hepatobiliary transport characteristics of PFASs, which may help understand the connection between PFAS accumulation and liver cancer risk.

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.

Biological effects of perfluoroalkyl substances on running water ecosystems: A case study in Beiluo River, China

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are emerging contaminants that pose a threat to the biodiversity of the Beiluo River, a polluted watercourse on the Loess Plateau impacted by diverse human activities. However, the occurrence, spatial distribution, and substitution characteristics of PFASs in this region remain unclear. This study aimed to unravel PFAS distribution patterns and their impact on the aquatic ecosystems of the Beiluo River Basin. The total PFAS concentration in the area ranged from 16.64-35.70 ng/L, with predominantly perfluorocarboxylic acids (PFCAs) and perfluorosulfonic acids (PFSAs), collectively contributing 94%. The Mantel test revealed threats to aquatic communities from both legacy long-chain (perfluorooctanoic acid and sodium perfluorooctane sulfonic acid) and emerging (6:2 fluorotelomer sulfonic acid, 2-Perfluorohexyl ethanoic acid, and hexafluoropropylene oxide dimer acid (Gen-X)) PFSAs. The canonical correspondence analysis ordination indicated that trace quantities of emerging PFASs, specifically 2-Perfluorohexyl ethanoic acid and hexafluoropropylene oxide dimer acid (Gen-X), significantly influenced geographical variations in aquatic communities. In conclusion, this study underscores the importance of comprehensively exploring the ecological implications and potential risks associated with PFASs in the Beiluo River Basin.

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

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