Polyfluoroalkyl Research Articles

Toxicity of Zwitterionic Perfluorinated Compounds in Water Hyacinth

Per- and polyfluoroalkyl substances (PFASs) pollution has become a hot environmental issue. PFASs have been detected in various types of environmental media and biological tissues, and the aquatic environment is an important “sink” for PFASs. As one of the most widely distributed organisms in aquatic environment, plants inevitably contact with PFASs, which may cause toxic effects in aquatic plants. However, most current studies focus on terrestrial plants and animals, but neglect the effects of PFASs in aquatic plants. Therefore, in this study, the freshwater plant, water hyacinth (Eichhornia crassipes), is selected as the research object to explore the toxic effects of zwitterionic perfluorinated compounds on aquatic plants. The results show that low concentration of perfluorooctaneamido betaine (PFOSB) (500 ng/L, 96 h) promotes the net photosynthetic rate of water hyacinth leaves, and the presence of perfluorooctanesulfonamido betaine (PFOAB) and PFOSB cause a significant increase in CAT activity in water hyacinth roots after 48 h. The antioxidant system is activated in response to the PFOAB and PFOSB stresses. This study provides a powerful theoretical basis for the toxic effects and ecological risks of zwitterionic PFASs in aquatic plants.

Machine learning identifies phenotypic profile alterations of human dopaminergic neurons exposed to bisphenols and perfluoroalkyls

Parkinson’s disease (PD) is the second most common neurodegenerative disease and is characterized by the loss of midbrain dopaminergic neurons. Endocrine disrupting chemicals (EDCs) are active substances that interfere with hormonal signaling. Among EDCs, bisphenols (BPs) and perfluoroalkyls (PFs) are chemicals leached from plastics and other household products, and humans are unavoidably exposed to these xenobiotics. Data from animal studies suggest that EDCs exposure may play a role in PD, but data about the effect of BPs and PFs on human models of the nervous system are lacking. Previous studies demonstrated that machine learning (ML) applied to microscopy data can classify different cell phenotypes based on image features. In this study, the effect of BPs and PFs at different concentrations within the real-life exposure range (0.01, 0.1, 1, and 2 µM) on the phenotypic profile of human stem cell-derived midbrain dopaminergic neurons (mDANs) was analyzed. Cells exposed for 72 h to the xenobiotics were stained with neuronal markers and evaluated using high content microscopy yielding 126 different phenotypic features. Three different ML models (LDA, XGBoost and LightGBM) were trained to classify EDC-treated versus control mDANs. EDC treated mDANs were identified with high accuracies (0.88–0.96). Assessment of the phenotypic feature contribution to the classification showed that EDCs induced a significant increase of alpha-synuclein (αSyn) and tyrosine hydroxylase (TH) staining intensity within the neurons. Moreover, microtubule-associated protein 2 (MAP2) neurite length and branching were significantly diminished in treated neurons. Our study shows that human mDANs are adversely impacted by exposure to EDCs, causing their phenotype to shift and exhibit more characteristics of PD. Importantly, ML-supported high-content imaging can identify concrete but subtle subcellular phenotypic changes that can be easily overlooked by visual inspection alone and that define EDCs effects in mDANs, thus enabling further pathological characterization in the future.

Strong Base Anion Exchange Selectivity of Nine Perfluoroalkyl Chemicals Relevant to Drinking Water.

Selectivity with respect to chloride () was determined for nine drinking water relevant perfluoroalkyl and polyfluoroalkyl substances (PFAS): perfluoro-2-propoxypropanoic acid (GenX), five perfluoroalkyl carboxylic acids (PFCAs), and three perfluoroalkyl sulfonic acids (PFSAs). Three single-use strong base anion exchange gel resins were investigated, targeting drinking water relevant equilibrium PFAS liquid concentrations (≤500 ng/L). Except for the longest carbon chain PFCA (perfluorodecanoic acid) and PFSA (perfluorooctanesulfonic acid) studied, PFAS followed traditional ion exchange theory (law of mass action), including increasing equilibrium PFAS liquid concentrations with increasing equilibrium chloride liquid concentrations. Overall, values were (i) similar among resins for a given PFAS, (ii) 1-5 orders of magnitude greater than the selectivity of inorganic anions (e.g., nitrate) previously studied, (iii) 2 orders of magnitude greater for the same carbon chain length PFSA versus PFCA, (iv) found to proportionally increase with carbon chain length for both PFSAs and PFCAs, and (v) similar for GenX and perfluorohexanoic acid (six-carbon PFCA). A multisolute competition experiment demonstrated binary isotherm-determined values could be applied to simulate a multisolute system, extending work previously done with only inorganic anions to PFAS. Ultimately, estimated values allow future extension and validation of an open-source anion exchange column model to PFAS.

Evidence for neurotoxicity and oxidative stress in zebrafish embryos/larvae treated with HFPO-DA ammonium salt (GenX)

"GenX" [ammonium perfluoro (2-methyl-3-oxahexanoate] was developed as a replacement chemical for toxic perfluorinated compounds to be used in product manufacturing. Here, we assessed developmental, mitochondrial, and behavioral toxicity endpoints in zebrafish embryos/larvae exposed to GenX. GenX exerted low toxicity to zebrafish embryos/larvae up to 20 mg/L. GenX did not affect mitochondrial oxidative phosphorylation nor ATP levels. ROS levels were reduced in larvae fish exposed to 10 and 100 µg/L, indicative of an antioxidant defense; however, ROS levels were elevated in fish exposed to 1000 µg/L. Increased expression of cox1 and sod2 in GenX exposed 7-day larvae was noted. GenX (0.1 or 1 µg/L) altered transcripts associated with neurotoxicity (elavl3, gfap, gap43, manf, and tubb). Locomotor activity of larvae was reduced by 100 µg/L GenX, but only in light periods. Perturbations of anxiety-related behaviors in larvae were not observed with GenX exposure. These data inform risk assessments for long-lived perfluorinated chemicals of concern.

Calotropis gigantea fiber confined ZIF-67 derived Co, N in-situ assembled hollow carbon fiber to activate peroxymonosulfate for degradation of perfluorooctanoic acid

Perfluorinated compounds have serious impacts on ecosystems and threats to human health, and exploring technologies to remove them is urgently needed. Using Calotropis gigantea fiber (CGF) as the biological template, the precursor of ZIF-67 was firstly in-situ anchored in the inner/outer walls of the fiber and then pyrolyzed to yield the composite catalyst labelled as Co/C@C. In combination with peroxymonosulfate (PMS), the advanced oxidation system, i.e. Co/C@C/PMS, was constructed for the catalytic removal of perfluorooctanoic acid (PFOA) from water. The experimental results showed that under the optimized conditions of PMS dosage of 1.0 g/L, catalyst dosage of 0.5 g/L and pH 3.0, PFOA achieved the degradation efficiency of 72.2% within 4 h at ambient temperature. Combined with free radical quenching, electron paramagnetic resonance, electrochemistry and nitroblue tetrazolium dichloride-based UV-Vis analysis, the reactive oxygen species and diverse pathways were identified, including SO4•−, O2•−, O21 and electron transfer process in the Co/C@C/PMS system. The coexisting anions (HCO3−, Cl−, H2PO4− and NO3−) and real wastewaters showed no significant effects on PFOA degradation, demonstrating that the Co/C@C/PMS system has good resistance to external ions and different media. After four cycles, the degradation efficiency of PFOA was still 62.8%, indicating that Co/C@C has high stability and good reusability. The degradation products of PFOA were mainly short-chain perfluorinated carboxylic acids (C4-C7) and hydrogen-substituted perfluorinated compounds. Based on quantitative structure-activity relationship analysis, their ecotoxicity was finally evaluated via ECOSAR method. In short, natural CGF derived Co/C@C has great potential for the reduction of emerging PFOA to achieve a sustainable water environment for humans.

Construction and operation characteristics of a fully quantified low-carbon treatment process for old landfill leachate

The feasibility of utilizing a coagulation-flocculation/sedimentation-denitrification (DN)/partial nitrification (PN)-anaerobic ammonium oxidation (Anammox)-electrochemical oxidation was investigated to achieve cost-effective and fully quantified treatment of leachate from old landfills, which contains lower C/N, higher NH4+-N and refractory chemical oxygen demand (CODr). The results indicated that the coagulation-flocculation/sedimentation, which aimed to remove the CODr, not only improved the nitrogen conversion efficiencies of the following PN and Anammox by 17.5 % and 105 %, respectively, but also benefited the solid phase enrichment of PO43− and the energy consumption of subsequent advanced treatment. The optimal dose of perfluorochemical (PFC) was found to be 1200 mg/L. The optimal electrode plate spacing and current density of the electrochemical oxidation process were 25 mm and 350 A/m2, respectively, and advanced treatment of the chemical oxygen demand (COD) and total nitrogen (TN) in the wastewater was achieved within 2 h. After 190 d of operation, the effluent quality met the required discharge standards. This process has the advantage of realizing full quantified treatment of wastewater and has significant environmental benefits.

The Effects of Combined Exposure to Bisphenols and Perfluoroalkyls on Human Perinatal Stem Cells and the Potential Implications for Health Outcomes.

The present study investigates the impact of two endocrine disruptors, namely Bisphenols (BPs) and Perfluoroalkyls (PFs), on human stem cells. These chemicals leach from plastic, and when ingested through contaminated food and water, they interfere with endogenous hormone signaling, causing various diseases. While the ability of BPs and PFs to cross the placental barrier and accumulate in fetal serum has been documented, the exact consequences for human development require further elucidation. The present research work explored the effects of combined exposure to BPs (BPA or BPS) and PFs (PFOS and PFOA) on human placenta (fetal membrane mesenchymal stromal cells, hFM-MSCs) and amniotic fluid (hAFSCs)-derived stem cells. The effects of the xenobiotics were assessed by analyzing cell proliferation, mitochondrial functionality, and the expression of genes involved in pluripotency and epigenetic regulation, which are crucial for early human development. Our findings demonstrate that antenatal exposure to BPs and/or PFs may alter the biological characteristics of perinatal stem cells and fetal epigenome, with potential implications for health outcomes at birth and in adulthood. Further research is necessary to comprehend the full extent of these effects and their long-term consequences.

Correlation analysis between per-fluoroalkyl and poly-fluoroalkyl substances exposure and depressive symptoms in adults: NHANES 2005–2018

BackgroundExcessive exposure to per and poly-fluoroalkyl compounds (PFAS) can lead to various negative health effects. However, there's a lack of research studying the link between PFAS exposure and depression in adults, and the existing findings are inconsistent. ObjectivesUtilizing data collected from the National Health and Nutrition Examination Survey (NHANES) database spanning 2005 to 2018, this study aimed to examine the potential connection between PFAS exposure and depressive symptoms in adults. MethodsThe correlation between individual PFAS exposure and depressive symptoms was examined through the establishment of weighted logistic regression models (crude model, model 1, model 2) and restricted cubic spline models. To verify the stability of the model, receiver operating characteristic (ROC) curves of the logistic regression model were generated, and a ten-fold cross-validation model was employed. Additionally, the relationship between adult depressive symptoms and mixed PFAS exposure was tested through the utilization of quantile g-computation (qgcomp). ResultsThe findings revealed that heightened exposure levels to PFOA, PFHxS, and PFUnDA, were connected with a diminished risk of depressive symptoms in adults (ORPFOA: 0.67, 95 % confidence interval (CI): 0.47, 0.95; ORPFHxS: 0.66, 95 %CI: 0.49, 0.89; ORPFUnDA: 0.65, 95 %CI: 0.45, 0.96). PFOS, PFHxS, and PFDA demonstrated a dose-response relationship with the risk of depressive symptoms. The ROC curve indicated model stability, with recognition accuracy exceeding 90 % in the cross-validation model. The outcomes of qgcomp demonstrated that an increase in serum PFAS concentration was linked to a decreased risk of depressive symptoms in adults (OR: 0.85, 95 %CI: 0.75, 0.96). DiscussionDue to the cross-sectional design of this study, it's important to acknowledge the potential for reverse causality between PFAS exposure and depressive symptoms. As a result, the outcomes should not be oversimplified to interpret PFAS exposure as a protective factor against adult depressive symptoms.

Fluorine-tailed glass fibers for adsorption of volatile perfluorinated compounds via F-F interaction

Perfluorinated compounds (PFCs) and their short-chain derivatives are contaminants found globally. Adsorption research on volatile perfluorinated compounds (VPFCs), which are the main PFCs substances that undergo transfer and migration, is particularly important. In this study, new fluorine-containing tail materials (FCTMs) were prepared by combining fluorine-containing tail organic compounds with modified glass fibers. The adsorption effects of these FCTMs were generally stronger than that of pure activated glass fibers without fluorine- tailed, with an adsorption efficiency of up to 86% based on F–F interactions. The results showed that the FCTMs had improved desorption efficiency and reusability, and higher adsorption efficiency compared with that of polyurethane foam. FTGF was applied to the active sampler, and the indoor adsorption of perfluorovaleric acid was up to 2.45 ng/m3. The adsorption kinetics and isotherm simulation results showed that the adsorption process of typical perfluorinated compounds conformed to the second-order kinetics and Langmuir model. Furthermore, Nuclear Magnetic Resonance (NMR) results showed that the chemical shift in the fluorine spectrum was significantly changed by F–F interactions. This research provides basic theoretical data for the study of VPFCs, especially short-chain VPFCs, facilitating improved scientific support for the gas phase analysis of VPFCs in the environment.

Metabolic characteristics and pathogenesis of precocious puberty in girls: the role of perfluorinated compounds

BackgroundPrecocious puberty (PP) in girls is traditionally defined as the onset of breast development before the age of 8 years. The specific biomarkers of premature thelarche (PT) and central precocious puberty (CPP) girls are uncertain, and little is known about their metabolic characteristics driven by perfluorinated compounds (PFCs) and clinical phenotype. This study aimed to screen specific biomarkers of PT and CPP and elucidate their underlying pathogenesis. The relationships of clinical phenotype-serum PFCs-metabolic characteristics were also explored to reveal the relationship between PFCs and the occurrence and development of PT and CPP.MethodsNuclear magnetic resonance (NMR)-based cross-metabolomics strategy was performed on serum from 146 PP (including 30 CPP, 40 PT, and 76 unspecified PP) girls and 64 healthy girls (including 36 prepubertal and 28 adolescent). Specific biomarkers were screened by the uni- and multivariate statistical analyses. The relationships between serum PFCs and clinical phenotype were performed by correlation analysis and weighted gene co-expression network analysis to explore the link of clinical phenotype-PFCs-metabolic characteristics in PT and CPP.ResultsThe disordered trend of pyruvate and butyrate metabolisms (metabolites mapped as formate, ethanol, and 3-hydroxybutyrate) were shared and kept almost consistent in PT and CPP. Eight and eleven specific biomarkers were screened for PT and CPP, respectively. The area under curve of specific biomarker combination was 0.721 in CPP vs. prepubertal, 0.972 in PT vs. prepubertal, 0.646 in CPP vs. prepubertal integrated adolescent, and 0.822 in PT vs. prepubertal integrated adolescent, respectively. Perfluoro-n-heptanoic acid and perfluoro-n-hexanoic acid were statistically different between PT and CPP. Estradiol and prolactin were significantly correlated with PFCs in CPP and PT. Clinical phenotypes and PFCs drive the metabolic characteristics and cause metabolic disturbances in CPP and PT.ConclusionsThe elevation of formate, ethanol, and 3-hydroxybutyrate may serve as the early diagnostic indicator for PP in girls. But the stratification of PP still needs to be further determined based on the specific biomarkers. Specific biomarkers of CPP and PT exhibited good sensitivity and can facilitate the classification diagnosis of CPP and PT. PFC exposure is associated with endocrine homeostasis imbalance. PFC exposure and/or endocrine disturbance directly or indirectly drive metabolic changes and form overall metabolic network perturbations in CPP and PT.

A review on recent advances in mass spectrometry analysis of harmful contaminants in food.

Food safety is a widespread global concern with the emergence of foodborne diseases. Thus, establishing accurate and sensitive detection methods of harmful contaminants in different food matrices is essential to address and prevent the associated health risks. Among various analytical tools, mass spectrometry (MS) can quantify multiple impurities simultaneously due to high resolution and accuracy and can achieve non-target profiling of unknown pollutants in food. Therefore, MS has been widely used for determination of hazardous contaminants [e.g., mycotoxin, pesticide and veterinary drug residues, polychlorinated biphenyls (PCBs), dioxins, acrylamide, perfluorinated compounds (PFCs) and p-Phenylenediamine compounds (PPDs) in food samples]. This work summarizes MS applications in detecting harmful contaminants in food matrices, discusses advantages of MS for food safety study, and provides a perspective on future directions of MS development in food research. With the persistent occurrence of novel contaminants, MS will play a more and more critical role in food analysis.

Perfluoroalkyl substances (PFAS) and lead (Pb) as “cardiovascular disruptors” in 9–11-year-old children living in Syracuse, New York, United States

ObjectivePer- and polyfluoro–alkyl substances (PFAS) and lead (Pb) are ubiquitous environmental toxicants with apparent impact on cardiovascular disease (CVD) risk. As one possible mechanism for this increased risk, we have previously demonstrated an association between Pb exposure and heightened cardiovascular reactivity to acute psychological stress, a CVD risk factor. The present study expands this approach and considers both PFAS and Pb exposures (and the possible interaction). MethodsWe assessed 14 serum PFAS and whole blood Pb concentrations in a sample of 9–11 year-old children (N = 291; 43.2% White, 56.8% Black; 53.5% female). We measured cardiovascular functioning at rest and during psychological stress as well as multiple indicators of subclinical CVD including resting blood pressure (BP), carotid-femoral pulse wave velocity (cfPWV), carotid intima-media thickness (cIMT), and left ventricular mass (LVM). Data analysis included general linear modeling as well as a non-parametric approach to study metal mixtures, specifically Bayesian Kernel Machine Regression (BKMR). ResultsSignificant interactions between different PFAS and with Pb suggest the importance of considering toxicant mixtures when assessing potential disruption of the cardiovascular system. The pattern of findings suggests that greater “vascular reactivity” (elevated BP and vascular resistance during acute psychological stress) was associated with higher concentrations of perfluorononanoic acid (PFNA), perfluorohexane sulfonate (PFHxS), and Pb, but only when perfluorooctanoic acid (PFOA) was concurrently elevated. With respect to subclinical outcomes, increasing perfluorodecanoic acid (PFDA) was associated with greater cIMT (β = 0.21, p = 0.010). ConclusionTo our knowledge this is the first study to consider how PFAS exposures might affect cardiovascular functioning and subclinical disease. Although a complex pattern of associations emerged, it does appear that PFAS and Pb can be classified as “cardiovascular disruptors” in children. Further research is needed to replicate these novel findings and determine whether these disruptions produce future cardiovascular disease.

A Study on Greenhouse Gas (PFCs) Reduction in Plasma Scrubbers to Realize Carbon Neutrality of Semiconductors and Displays

Perfluorinated compounds (PFCs) are used for manufacturing purposes in the semiconductor and display industries, resulting in an increased need for emission reduction due to the significant global warming potential of the associated greenhouse gases. The decomposition characteristics of etch-type and water film (WF)-type plasma-wet scrubbers were investigated. The PFCs used in the study were CF4, SF6, NF3, CHF3, C2F6, C3F8, and C4F8, and the destruction removal efficiency (DRE) and by-product gas generation rate were confirmed based on the changes in the parameters (total flow rate and power) of the plasma-wet scrubber. When the total flow rate reached 100 L/min and the measured maximum power (11 kW), the reduction efficiency of CF4 in the etch type was 95.60% and the DRE of other PFCs was 99.99%. Moreover, for the WF type, the DRE of CF4 was 90.06%, that of SF6 was 96.44%, and that of other PFCs was 99.99%. When the total flow rate reached 300 L/min and 11 kW, the DRE of SF6 in the etch type was 99%, and the DRE of NF3, CHF3, C2F6, C3F8, and C4F8 was 95.57%, 87.06%, 70.74%, 81.45%, and 95.59%, respectively. In addition, in the WF type, the DRE of SF6 was 94.39%, and the DRE of NF3, CHF3, C2F6, C3F8, and C4F8 was 99.80%, 95.34%, 85.38%, 88.49%, and 98.22%, respectively. The decomposition efficiency was high for the etch type for gases with small flow rates or no by-product gas generation. The by-product gas generation rate was significantly lower for the WF type.

Environmental explanation of prostate cancer progression based on the comprehensive analysis of perfluorinated compounds

Perfluorinated compounds (PFCs) are man-made chemicals used in the manufacture of many products with water and dirt repellent properties. Many diseases have been proved to be related to the exposure of PFCs, including breast fibroadenoma, hepatocellular carcinoma, breast cancer and leydig cell adenoma. However, whether the PFCs promote the progression of prostate cancer remains unclear. In this work, through comprehensive bioinformatics analysis, we discovered the correlation between the prostate cancer and five PFCs using Comparative Toxicogenomics Database (CTD), Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases. In addition, further analysis showed that several PFCs-related genes demonstrated strong prognostic value for prostate cancer patients. The survival analysis and receiver operating characteristic (ROC) curves revealed that PFCs-related genes based prognostic model held great predictive value for the prognosis of prostate cancer, which could potentially serve as an independent risk factor in the future. In vitro experiments verified the promotive role of perfluorooctanoic acid (PFOA) and perfluorononanoic acid (PFNA) in the growth of prostate cancer cells. This study provided novel insights into understanding the role of PFCs in prostate cancer and brought attention to the environmental association with cancer risks and progression.

Antenatal Exposure to Plastic Pollutants: Study of the Bisphenols and Perfluoroalkyls Effects on Human Stem Cell Models

Endocrine disruptors (EDs), such as Bisphenols (BPs) and Perfluoroalkyls (PFs), are a class of plastic pollutants widely used in industrial applications. Human exposure to these molecules usually occurs through ingestion of contaminated food and water. Once entered the human body they can interfere with endogenous hormone signaling, leading to a wide spectrum of diseases. It has been reported that BPs and PFs can cross the placental barrier accumulating in the fetal serum, but the detrimental consequences for human development remain to be clarified. Here we analyze the effects of different doses of bisphenol A and S (BPA, BPS) perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) on proliferation and mitochondrial health on different types of stem cells: through an integrated approach that combines data from pluripotent stem cells (hiPSCs) with that from the “environment” in which the embryo develops (fetal annexes-derived perinatal stem cells) we verified the potential developmental toxicity of the in utero EDs exposure. Data obtained showed that overall, BPs, and PFs tended to increase the proliferation rate of perinatal stem cells; a similar response was observed in hiPSCs exposed to very low doses of BPs and PFs, while at higher concentrations these chemicals were toxic; in addition, both the BPs and the PFs exerted a mitotoxic effects hiPSCs at all the concentration studied. All these data suggest that antenatal exposure to BPs and PFs, also at very low concentrations, may modify the biological characteristics of stem cells present in both the developing fetus and the fetal annexes, thus perturbing normal human development.

Amine-Functionalized A-Center Sphalerite for Selective and Efficient Destruction of Perfluorooctanoic Acid.

Perfluorochemicals (PFCs), especially perfluorooctanoic acid (PFOA), have contaminated the ground and surface waters throughout the world. Efficient removal of PFCs from contaminated waters has been a major challenge. This study developed a novel UV-based reaction system to achieve fast PFOA adsorption and decomposition without addition of sacrificial chemicals by using synthetic photocatalyst sphalerite (ZnS-[N]) with sufficient surface amination and defects. The obtained ZnS-[N] has the capability of both reduction and oxidation due to the suitable band gap and photo-generated hole-trapping properties created by surface defects. The cooperated organic amine functional groups on the surface of ZnS-[N] play a crucial role in the selective adsorption of PFOA, which guarantee the efficient destruction of PFOA subsequently, and 1 μg L-1 PFOA could be degraded to <70 ng L-1 after 3 h in the presence of 0.75 g L-1 ZnS-[N] under 500 W UV irradiation. In this process, the photogenerated electrons (reduction) and holes (oxidation) on the ZnS-[N] surface work in a synergistic manner to achieve complete defluorination of PFOA. This study not only provides promising green technology for PFC-pollution remediation but also highlights the significance of developing a target system capable of both reduction and oxidation for PFC degradation.

Toxic effects of perfluorocaproic acid (PFHxA) on crucian carp (Carassius auratus) and the response of the intestinal microbial community

Perfluorocaproic acid (PFHxA), a short-chain substitute for the emerging contaminant perfluorinated compounds, has been detected in the aquatic environment. However, its aquatic toxicity and health risk assessment are mainly unknown. In this study, we compared the toxic doses of 0 mg/L, 5 mg/L, 15 mg/L, 45 mg/L and 135 mg/L on the pathological damage to tissue sections, antioxidant indexes and inflammatory factor expressions in liver, spleen, kidney, Prosogaster, Mid-gut, Hid-gut as well as the changes of IgM, C3, C4, LZM, GOT, GPT in serum of crucian carp. We determined the response of the intestinal microbial community to PFHxA stress by 16S. The results showed that the growth performance of crucian carp was slowed with the increase of PFHxA dose, which caused different degrees of damage to the tissues. Meanwhile, the indexes of SOD, GSH-Px, T-AOC, ACP, AKP and LZM in each tissue were reduced, and the indexes of IgM, C3, C4 and LZM in serum were reduced. The levels of MDA, GOT and GPT in tissues and GOT and GPT in serum were promoted. In addition, IL-1β, TNF-α, NF-KB, and KEAP-1 in each tissue increased compared with the control group. The levels of IL-10, Nrf2, CAT, and GPx were decreased. The 16S rRNA gene sequencing results showed that PFHxA significantly reduced the abundance and diversity of the gut microbiota. It is suggested that PFHxA is likely to cause different degrees of damage to various tissues by disrupting the diversity of the intestinal flora. These results provide insights to facilitate the risk assessment of PFHxA contaminants in the aquatic environment.

Non-fluorine oil repellency: To what extent can it substitute perfluoroalkyl substances?

Oil-repellency of fabric is essentially based on perfluoroalkyl substances (PFAS, or called perfluorochemicals (PFCs)). However, plans to phase out the use of these chemicals, even those short-chain ones (C4-C6), have been announced because they accumulate in the human body and are extremely persistent in the environment. It is urgent to develop non-fluorine surface chemistry for oil-repellent fabric finishing. Here, we report the non-fluorine oil repellency of brush-like polydimethylsiloxane (PDMS) coating (g-PDMS), and the comparison of its oil repellency with that of a common PFAS crosslink polysiloxane coating (C4-PFAS). A catalyst-free, solvent-free chemical vapor deposition (CVD) process was used to prepare the g-PDMS coating. For smooth glass, g-PDMS coating exhibits ultralow contact angle hysteresis (∆θ) for various oils (1.3–7.3°), while the ∆θ of C4-PFAS coating is much higher (30.7–49.7°). For fabrics, g-PDMS and C4-PFAS achieved almost the same contact angles to castor oil (~134°). According to GB/T 19977-2014 standard, the oil repellency of coated fabrics was rated Grade 5 for both g-PDMS and C4-PFAS. Therefore, the non-fluorine oil repellency of g-PDMS is able to meet the basic requirement of oil-repellent fabric finishing, and it is expected that the oil repellency can be further improved by the rational design on surface topography.

Preliminary results from the Tunisian monitoring program on POPs in air under the Stockholm Convention

Persistent organic pollutants (POPs) have been measured using passive air samplers (PASs) over two years (2017–2018) in the city of Tunis within the framework of the UNEP/GEF GMP2 projects to support Stockholm Convention implementation. Several POPs, although banned for a long time from Tunisia, were registered in relatively high amounts in the atmospheric compartment. The most unexpected compound is hexachlorobenzene (HCB), with concentrations ranging from 5.2 ng/PUF to 16 ng/PUF. Furthermore, the current results seem to confirm the presence of dichlorodiphenyltrichloroethane (DDT) and its transformation products and hexachlorocyclohexanes (HCHs) at relatively high concentrations (4.6 ng/PUF to 9.4 ng/PUF and 2.7 ng/PUF to 5.1 ng/PUF, respectively), followed by hexabromocyclododecane (HCBD), which varies from 1.5 ng/PUF to 7.7 ng/PUF. Nondioxin-like PCB (ndl-PCB) concentrations in Tunis were very high (62.0 ng/PUF to 419.3 ng/PUF), higher than those in other African countries participating in this project. Uncontrolled combustion seems to be one of the most important sources of the emanation of dioxin compounds dl-PCBs and Polychlorinated dibenzodioxins PCDD/polychlorinated dibenzofurans PCDF. Toxic equivalents (TEQs) ranged from 4.1 pg WHO-TEQ/PUF to 6.4 pg WHO-TEQ/PUF. The perfluorinated compounds (PFAS) and congeners of polybrominated diphenyl ethers (PBDEs) show relatively low amounts that remain below the African continent average. The PFAS pattern suggests a local source rather than long-range transport. These results constitute the first exhaustive work capable of providing an overview of the levels of POPs in the air in Tunis. As a result, it will be possible to set up an adequate monitoring program with specific investigations and experimental studies.

Spherical amino-functionalized covalent organic frameworks: Synthesis and adsorption performance toward perfluorinated compounds

Perfluorinated compounds (PFCs) are widely used in textiles, fire protection, metal electroplating, and semiconductor production owing to their hydrophobic and oil-repellent characteristics. However, they are also persistent organic pollutants. The uncontrolled discharge of PFCs into the environment has led to serious global pollution. PFCs pose severe reproductive, neural, immune, and other threats to human health by accumulating through the food chain. Thus, the development and application of high-performance extraction materials has become a research hotspot in efforts to achieve the accurate detection of trace PFCs in environmental waters. Most traditional PFC adsorbents present a number of disadvantages, such as low adsorption selectivity, slow diffusion, and poor reusability. Covalent organic frameworks (COFs) are crystalline polymers with ordered porous structures, large specific surface areas, and high chemical and thermal stability. These frameworks can easily be functionalized for the desired purpose. In this paper, spherical amino-functionalized COFs (denoted COF-NH2) were fabricated via a two-step method to effectively enrich/remove PFCs from water. First, vinyl covalent organic framework (Vinyl COF) was synthesized at room temperature using 1,4-diradical-2,5-divinylbenzene (Dva) and 1,3,5-tris(4-aminophenyl)benzene (Tab) as building blocks. Then, thioether-bridged aromatic amine-functionalized spherical COF-NH2 was synthesized through a thiol-alkenyl click reaction using 4-aminothiophenol as the functional monomer. COF-NH2 showed good dispersion in water owing to its abundant amino groups, forming multiple hydrogen bonds with the F atoms of PFCs. The synergistic hydrophobic interactions between the organic skeleton of the COF and alkyl carbon chains of the PFCs led to enhanced adsorption efficiency. The produced Vinyl COF and COF-NH2 were characterized by Fourier transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), and Brunner-Emmet-Teller (BET) measurements. The results confirmed that spherical COF-NH2 materials with a homogeneous size distribution were successfully fabricated. The obtained COF-NH2 microspheres had a diameter of approximately 500 nm and exhibited high thermal stability as well as a large specific surface area and pore volume. The adsorption kinetics, isotherm adsorption models, pH effects, and regeneration properties of COF-NH2 were also investigated, and the results indicated that the adsorption of PFCs by COF-NH2 conformed to the pseudo-second-order kinetic and Langmuir isotherm adsorption models. The obtained COF-NH2 microspheres can be applied over a wide pH range, and the best adsorption effect was achieved in neutral and alkaline environments. After five cycles of regeneration and reuse, the COF-NH2 microspheres retained their good adsorption efficiency for PFCs. The adsorption mechanism was mainly attributed to the synergistic effect of hydrogen bonding and hydrophobic interactions between COF-NH2 and the PFCs. The extraction efficiencies of the microspheres toward five PFCs (perfluorobutyric acid, perfluorovaleric acid, perfluorohexanoic acid, perfluorooctanoic acid, and perfluorononanoic acid) in tap and Pearl River water samples were between 91.76% and 98.59%, with relative standard deviations (RSDs) (n=3) varying from 0.82% to 3.8%; these findings indicate that the obtained COF-NH2 is promising for the extraction of PFCs from complex water samples. Given their uniform size distribution, high thermal stability, good adsorption performance, and reusability, the novel spherical COF-NH2 materials developed in this study may be used as solid-phase extraction materials or filled into liquid chromatographic columns for the enrichment, separation, and detection of PFCs in complex samples.