Tainted water: the scientists tracing thousands of fluorinated chemicals in our environment

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

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

Machine learning-enhanced molecular network reveals global exposure to hundreds of unknown PFAS

Unknown forever chemicals like per- and polyfluoroalkyl substances (PFASs) are difficult to identify. Current platforms designed for metabolites and natural products cannot capture the diverse structural characteristics of PFAS. Here, we report an automatic PFAS identification platform (APP-ID) that screens for PFAS in environmental samples using an enhanced molecular network and identifies unknown PFAS structures using machine learning. Our networking algorithm, which enhances characteristic fragment matches, has lower false-positive rate (0.7%) than current algorithms (2.4 to 46%). Our support vector machine model identified unknown PFAS in test set with 58.3% accuracy, surpassing current software. Further, APP-ID detected 733 PFASs in real fluorochemical wastewater, 39 of which are previously unreported in environmental media. Retrospective screening of 126 PFASs against public data repository from 20 countries show PFAS substitutes are prevalent worldwide.

Electrostatic Field in Contact-Electro-Catalysis Driven C-F Bond Cleavage of Perfluoroalkyl Substances

Perfluoroalkyl substances (PFASs) are persistent and toxic to human health. It is demanding for high-efficient and green technologies to remove PFASs from water. In this study, a novel PFAS treatment technology was developed, utilizing polytetrafluoroethylene (PTFE) particles (1-5 μm) as the catalyst and a low frequency ultrasound (US, 40 kHz, 0.3 W/cm2) for activation. Remarkably, this system can induce near-complete defluorination for different structured PFASs. The underlying mechanism relies on contact electrification between PTFE and water, which induces cumulative electrons on PTFE surface, and creates a high surface voltage (tens of volts). Such high surface voltage can generate abundant reactive oxygen species (ROS, i.e., O2⋅-, HO⋅, etc.) and a strong interfacial electrostatic field (IEF of 109~1010 V/m). Consequently, the strong IEF significantly activates PFAS molecules and reduces the energy barrier of O2⋅- nucleophilic reaction. Simultaneously, the co-existence of surface electrons (PTFE*(e-)) and HO⋅ enables synergetic reduction and oxidation of PFAS and its intermediates, leading to enhanced and thorough defluorination. The US/PTFE method shows compelling advantages of low energy consumption, zero chemical input, and few harmful intermediates. It offers a new and promising solution for effectively treating the PFAS-contaminated drinking water.

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.

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

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

Occurrences and fates of per- and polyfluoralkyl substances in textile dyeing wastewater along full-scale treatment processes

Industrial wastewater is a substantial source of per- and polyfluoroalkyl substances (PFASs) in the environment. However, very limited information is available on the occurrences and fates of PFASs along industrial wastewater treatment processes, particularly for the textile dyeing industry where PFASs occur extensively. Herein, the occurrences and fates of 27 legacy and emerging PFASs were investigated along the processes of three full-scale textile dyeing wastewater treatment plants (WWTPs) based on UHPLC-MS/MS in combination with self-developed solid extraction protocol featuring selective enrichment for ultrasensitive analysis. The total PFASs ranged at 630-4268 ng L-1 in influents, 436-755 ng L-1 in effluents, and 91.5-1182 μg kg-1 in the resultant sludge. PFAS species distribution varied among WWTPs, with one WWTP dominated by legacy perfluorocarboxylic acids while the other two dominated by emerging PFASs. Perfluorooctane sulfonate (PFOS) was trivial in the effluents from all the three WWTPs, indicating its diminished use in textile industry. Various emerging PFASs were detected at different abundances, demonstrating their use as alternatives to legacy PFASs. Most conventional processes of the WWTPs were inefficient in removing PFASs, especially for the legacy PFASs. The microbial processes could remove the emerging PFASs to different extents, whereas commonly elevated the concentrations of legacy PFASs. Over 90% of most PFASs could be removed by reverse osmosis (RO) and was enriched into the RO concentrate accordingly. The total oxidizable precursors (TOP) assay revealed that the total concentration of PFASs was increased by 2.3-4.1 times after oxidation, accompanied by formation of terminal perfluoroalkyl acids (PFAAs) and degradation of emerging alternatives to various extents. This study is believed to shed new light on the monitoring and management of PFASs in industries.

Exposures to perfluoroalkyl substances and asthma phenotypes in childhood: an investigation of the COPSAC2010 cohort

BACKGROUND

Exposure to perfluoroalkyl substances may affect offspring immune development and thereby increase risk of childhood asthma, but the underlying mechanisms and asthma phenotype affected by such exposure is unknown.

METHODS

In the Danish COPSAC2010 cohort of 738 unselected pregnant women and their children plasma PFOS and PFOA concentrations were semi-quantified by untargeted metabolomics analyses and calibrated using a targeted pipeline in mothers (gestation week 24 and 1 week postpartum) and children (age ½, 1½ and 6 years). We examined associations between pregnancy and childhood PFOS and PFOA exposure and childhood infections, asthma, allergic sensitization, atopic dermatitis, and lung function measures, and studied potential mechanisms by integrating data on systemic low-grade inflammation (hs-CRP), functional immune responses, and epigenetics.

FINDINGS

Higher maternal PFOS and PFOA exposure during pregnancy showed association with a non-atopic asthma phenotype by age 6, a protection against sensitization, and no association with atopic asthma or lung function, or atopic dermatitis. The effect was primarily driven by prenatal exposure. There was no association with infection proneness, low-grade inflammation, altered immune responses or epigenetic changes.

INTERPRETATIONS

Prenatal exposure to PFOS and PFOA, but not childhood exposure, specifically increased the risk of low prevalent non-atopic asthma, whereas there was no effect on atopic asthma, lung function, or atopic dermatitis.

FUNDING

All funding received by COPSAC are listed on www.copsac.com. The Lundbeck Foundation (Grant no R16-A1694); The Novo Nordic Foundation (Grant nos NNF20OC0061029, NNF170C0025014, NNF180C0031764); The Ministry of Health (Grant no 903516); Danish Council for Strategic Research (Grant no 0603-00280B); and The Capital Region Research Foundation have provided core support to the COPSAC research center. COPSAC acknowledges the National Facility for Exposomics (SciLifeLab, Sweden) for supporting calibration of the untargeted metabolomics PFAS data. BC and AS has received funding for this project from the European Union's Horizon 2020 research and innovation programme (BC: grant agreement No. 946228 DEFEND; AS: grant agreement No. 864764 HEDIMED).

Water quality of The Gambia River: A prospective drinking water supply

Drinking water in The Gambia is mostly derived from boreholes that could potentially be contaminated. The Gambia River, a major river in West Africa that covers 12 % of the country's area, could be more exploited for drinking water supply. During the dry season, the total dissolved solids (TDS), ranging from 0.02 to 33 g/L in The Gambia River, decreases with the distance to the river mouth with no major inorganic contamination. The freshwater (<0.8 g/L TDS) starts from Jasobo at approximately 120 km from the river mouth and extends by about 350 km to the eastern border of The Gambia. With a dissolved organic carbon (DOC) ranging from 2 to 15 mgC/L, the natural organic matter (NOM) of The Gambia River was characterised by 40-60 % humic substances of paedogenic origin. With such characteristics, unknown disinfection by-products could be formed if chemical disinfection, such as chlorination, was implemented during treatment. Out of 103 types of micropollutants, 21 were detected (4 pesticides, 10 pharmaceuticals, 7 per- and polyfluoroalkyl substances (PFAS)) with concentrations ranging from 0.1 to 1500 ng/L. Pesticides, bisphenol A and PFAS concentrations were below the stricter EU guidelines set for drinking water. These were mainly confined to the urban area of high population density near the river mouth, while the quality of the freshwater region of low population density was surprisingly pristine. These results indicate that The Gambia River, especially in its upper regions, would be well suited as a drinking water supply when using decentralised ultrafiltration treatment for the removal of turbidity, as well as, depending on pore size, to a certain extent microorganisms and DOC.

Effects of PFOS, F-53B and OBS on locomotor behaviour, the dopaminergic system and mitochondrial function in developing zebrafish (Danio rerio)

Perfluorooctanesulfonic acid (PFOS) has widely been reported to persist in the environment and to elicit neurotoxicological effects in wildlife and humans. Following the restriction of PFOS use, 6:2 chlorinated polyfluorinated ether sulfonate (F-53B) and sodium p-perfluorous nonenoxybenzene sulfonate (OBS) have emerged as novel PFOS alternatives and have been detected in the environment. However, knowledge on the toxicological effects of these alternatives remains scarce. Using developing transgenic Tg(dat:eGFP) zebrafish, we evaluated the consequences of exposure to 0, 0.1 and 1 mg/l PFOS, F-53B and OBS on the dopaminergic system, locomotor behaviour and mitochondrial function. All compounds generally reduced locomotor activity under light conditions irrespective of exposure concentration. Exposure to OBS (at all concentrations), as well as PFOS and F-53B (at 1 mg/l), significantly reduced subpallial dopaminergic neuron abundance. PFOS also significantly reduced dat and pink1 expression irrespective of exposure concentration, while F-53B and OBS tended to reduce mitochondrial pink1 and fis1 expression across concentrations without reaching statistical significance. Mitochondrial function, in the form of reduced oxygen consumption rate and marginally inhibited ATP-linked oxygen consumption rate, was affected only in response to 1 mg/l PFOS. Together, PFOS and the emerging contaminants F-53B and OBS inhibit locomotion at similar concentrations, a finding correlated with decreased dopaminergic neuron numbers in the subpallium and decreased expression of pink1. These findings are relevant to wildlife and human health, as they suggest that PFOS as well as replacement compounds affect locomotion likely in part by negatively impacting the dopamine system.

Nutrition paves the way to environmental toxicants and influences fetal development during pregnancy

Nutrition plays a major role in the healthy pregnancy and development of the fetus. In addition, nutrition can expose humans to a wide range of potentially hazardous environmental constituents, such as organic pollutants and heavy metals from marine or agricultural food products while processing, producing, and packaging. Humans constantly face these constituents through air, water, soil, food, and domestic products. During pregnancy, the rate of cellular division and differentiation is higher; exposure to any of these environmental toxicants can lead to developmental defects as they cross the placental barrier and, in some cases, can harm the successive generation too, as some contaminants can act on the reproductive cells of the fetus (Diethylstilbestrol). Pregnant women are considered a vulnerable population to food contaminant exposure and require a proper dietary chart and conscious food choices. Food is a source of both essential nutrients and environmental toxicants. Here, we have researched the possible toxicants of the food industry and their influence on the fetus's in-utero development, along with the importance of dietary interventions and the need to balance a healthy diet to overcome the harms. The cumulative exposure to environmental toxicants can influence the mother's prenatal environment and affect the fetus's development.

Effects of perfluorooctanoic acid on Microcystis aeruginosa: Stress and self-adaptation mechanisms

The persistent organic pollutant perfluorooctanoic acid (PFOA) is ubiquitous in aquatic environments. However, little is known about its toxicity to microalgae or the mechanisms by which they may self-adapt to it. We found that growth of the bloom-forming cyanobacterium Microcystis aeruginosa was initially inhibited, with inhibition attenuated after 12 d of PFOA exposure. Growth inhibition gradually decreased and stabilized over time. With increasing PFOA concentration, reactive oxygen species levels and superoxide dismutase and photosystem II activity significantly increased, while respiration, NDH-1 activity, and total carbohydrate content significantly decreased. Self-adaptation mechanisms included antioxidant pathways, energy transfer and distribution of photosystems, and repair of the PSI and NDH complexes. The patterns of change in these parameters were consistent with those of the expression levels of genes in their associated metabolic pathways. Our data suggest that PSII overcompensation might be a strategy by which M. aeruginosa contends with oxidative stress induced by PFOA. Multiple downstream photosynthesis-related proteins were upregulated as a function of PFOA exposure time. These findings may help elucidate physiological, genetic stress and self-adaptive responses of microalgae to PFOA exposure.

Automated and fast online method for simultaneously determining a broad spectrum of per- and polyfluoroalkyl substances in a small volume of cerebrospinal fluid

Per- and polyfluoroalkyl substances (PFASs) are potentially neurotoxic compounds. Levels of PFASs in cerebrospinal fluid (CSF) could directly reflect their potential harm to the central nervous system. Because of the variety of PFASs and the rarity of CSF, there is an urgent need to establish a rapid online method to detect a broad spectrum of PFASs accurately and simultaneously by consuming a small amount of CSF. In this study, we developed a fast and automated method to analyze 52 PFASs in human CSF samples using online TurboFlow ultra-high-performance liquid chromatography-tandem mass spectrometry. Our method offered excellent matrix-matched standard curve linearity (correlation coefficient > 0.99), good limits of quantitation (MLOQs) (0.01 to 0.08 ng mL^-1), satisfactory accuracy (recoveries of 74.6%-119.1%) and precision (relative standard deviations of 1.4%-13.2%), small sample amount consumption (50 μL), and fast analysis time (18 min per sample) without complex sample pretreatment procedures. These are advantageous for the high throughput screening of PFASs in environmental epidemiology studies. Repeated freeze-thaw experiments showed that it was better to perform the analytical process soon as possible after sample collection. The established method was used to analyze PFASs in 60 people. Short-chain PFASs, perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPeA), and novel PFASs [sodium 2-(N-ethylperfluorooctane-1-sulfonamido)ethyl phosphate (SAmPAP), perfluoroethylcyclohexanesulfonate (PFECHS), and perfluoro-3, 7-dimethyloctanoic acid (P37DMOA)] were reported in CSF for the first time. PFBA and PFPeA were detected in all samples with mean concentrations of 0.24 and 0.22 ng mL^-1, respectively. We also calculated the blood-brain barrier transmission efficiency of PFASs (R_PFAS), and the mean R_PFBA value was above 1, which indicated that PFBA might transfer from serum to CSF.

Transport and transformation of perfluoroalkyl acids, isomer profiles, novel alternatives and unknown precursors from factories to dinner plates in China: New insights into crop bioaccumulation prediction and risk assessment

Perfluoroalkyl acids (PFAAs) are contaminants of global concern, and the inadvertent consumption of PFAA-contaminated crops may pose a threat to public health. Therefore, systematically studying their source tracing, bioaccumulation prediction and risk assessments in crops is an urgent priority. This study investigated the source apportionment and transport of PFAAs and novel fluorinated alternatives (collectively as per- and polyfluoroalkyl substances, PFASs) from factories to agricultural fields in a fluorochemical industrial region of China. Furthermore, bioaccumulation specificities and prediction of these chemicals in different vegetables were explored, followed by a comprehensive risk assessment from agricultural fields to dinner plates which considered precursor degradation. A positive matrix factorization model revealed that approximately 70 % of PFASs in agricultural soils were derived from fluorochemical manufacturing and metal processing. Alarming levels of ∑PFASs ranged 8.28-84.3 ng/g in soils and 163-7176 ng/g in vegetables. PFAS with short carbon chain or carboxylic acid group as well as branched isomers exhibited higher environmental transport potentials and bioaccumulation factors (BAFs) across a range of vegetables. The BAFs of different isomers of perfluorooctanoic acid (PFOA) decreased as the perfluoromethyl group moved further from the acid functional group. Hexafluoropropylene oxide dimer acid (GenX) showed relatively low BAFs, probably related to its ether bond with a high affinity to soil. Vegetables with fewer Casparian strips (e.g., carrot and radish), or more protein, possessed larger BAFs of PFASs. A bioaccumulation equation integrating critical parameters of PFASs, vegetables and soils, was built and corroborated with a good contamination prediction. After a total oxidizable precursors (TOP) assay, incremental perfluoroalkyl carboxylic acids (PFCAs) were massively found (325-5940 ng/g) in edible vegetable parts. Besides, precursor degradation and volatilization loss of PFASs was firstly confirmed during vegetable cooking. A risk assessment based on the TOP assay was developed to assist the protection of vegetable consumers.

Fluorotelomer alcohols are efficiently biotransformed by Cunninghamella elegans

Cunninghamella elegans is a well-studied fungus that biotransforms a range of xenobiotics owing to impressive cytochrome P450 (CYP) activity. In this paper, we report the biotransformation of 6:2 fluorotelomer alcohol (6:2 FTOH) by the fungus, yielding a range of fluorinated products that were detectable by fluorine-19 nuclear magnetic resonance spectroscopy (¹⁹F NMR), gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). Upon incubation with the pre-grown cultures, the substrate (100 mg/L) was completely consumed within 48 h, which is faster biotransformation than other fungi that have hitherto been studied. The main metabolite formed was the 5:3 fluorotelomer carboxylic acid (5:3 FTCA), which accumulated in the culture supernatant. When the cytochrome P450 inhibitor 1-aminobenzotriazole was included in the culture flasks, there was no biotransformation of 6:2 FTOH, indicating that these enzymes are key to the catalysis. Furthermore, when exogenous 5:3 FTCA was added to the fungus, the standard biotransformation of the drug flurbiprofen was inhibited, strongly suggesting that the main fluorotelomer alcohol biotransformation product inhibits CYP activity and accounts for its accumulation.

Efficient Recognition and Removal of Persistent Organic Pollutants by a Bifunctional Molecular Material

Persistent organic pollutants (POPs) exist widely in the environment and place significant impact on human health by bioaccumulation. Efficient recognition of POPs and their removal are highly challenging tasks because their specific structures interact often very weakly with the capture materials. Herein, a molecular nanocage (1) is studied as an efficient sensing and sorbent material for POPs, which is demonstrated by a representative and stable perfluorooctane sulfonate (PFOS) substrate containing a hydrophilic sulfonic group and a hydrophobic fluoroalkyl chain. A highly sensitive and unusual turn-on fluorescence response within 10 s and a 97% total removal of PFOS from water in 20 min have been achieved owing to the strong host-guest interactions between 1 and PFOS. The binding constant of 1 to PFOS is 2 orders of magnitude higher than state-of-the-art adsorbents for PFOS and thus represents a new benchmark material for the recognition and removal of PFOS. The host-guest interaction has been elucidated by solid-state NMR spectroscopy and single-crystal X-ray diffraction, which provide key insights at a molecular level for the design of new advanced sensing/sorbent materials for POPs.

Non-targeted proteomics reveals altered immune response in geographically distinct populations of green sea turtles (Chelonia mydas)

All seven species of sea turtle are facing increasing pressures from human activities that are impacting their health. Changes in circulating blood proteins of an individual, or all members of a population, can provide an early indicator of adverse health outcomes. Non-targeted measurement of all detectable proteins in a blood sample can indicate physiological changes. In the context of wildlife toxicology, this technique can provide a powerful tool for discovering biomarkers of chemical exposure and effect. This study presents a non-targeted examination of the protein abundance in sea turtle plasma obtained from three geographically distinct foraging populations of green turtles (Chelonia mydas) on the Queensland coast. Relative changes in protein expression between sites were compared, and potential markers of contaminant exposure were investigated. Blood plasma protein profiles were distinct between populations, with 85 out of the 116 identified proteins differentially expressed (p < 0.001). The most strongly dysregulated proteins were predominantly acute phase proteins, suggestive of differing immune status between the populations. The highest upregulation of known markers of immunotoxicity, such as pentraxin fusion and complement factor h, was observed in the Moreton Bay turtles. Forty-five different organohalogens were also measured in green turtle plasma samples as exposure to some organohalogens (e.g., polychlorinated biphenyls) has previously been identified as a cause for immune dysregulation in marine animals. The few detected organohalogens were at very low (pg/mL) concentrations in turtles from all sites, and are unlikely to be the cause of the proteome differences observed. However, the changes in protein expression may be indicative of exposure to other chemicals or environmental stressors. The results of this study provide important information about differences in protein expression between different populations of turtles, and guide future toxicological and health studies on east-Australian green sea turtles.

Diffusive gradients in thin films (DGT) probe for effectively sampling of per- and polyfluoroalkyl substances in waters and sediments

The passive sampling technique, diffusive gradients in thin films (DGT) has attracted increasing interests as an in-situ sampler for organic contaminants including per- and polyfluoroalkyl substances (PFAS). However, its effectiveness has been questioned because of the small effective sampling area (3.1 cm²). In this study, we developed a DGT probe for rapid sampling of eight PFAS in waters and applied it to a water-sediment system. It has a much larger sampling area (27 cm²) and as a result lower method quantification limits (0.15 - 0.21 ng/L for one-day deployment and 0.02 - 0.03 ng/L for one-week deployment) and much higher (by > 10 factors) sampling rate (100 mL/day) compared to the standard DGT (piston configuration). The sampler could linearly accumulate PFAS from wastewater, was sensitive enough even for a 24 hr deployment with performance comparable to grab sampling (500 mL). The DGT probe provided homogeneous sampling performance along the large exposure area. The use of the probe to investigate distributions of dissolved PFAS around the sediment-water interface was demonstrated. This work, for the first time, demonstrated that the DGT probe is a promising monitoring tool for trace levels of PFAS and a research tool for studying their distribution, migration, and fate in aquatic environments including the sediment-water interface.

Supramolecular assemblies of a newly developed indole derivative for selective adsorption and photo-destruction of perfluoroalkyl substances

Per-/polyfluoroalkyl substances (PFASs) contamination has caused worldwide health concerns, and increased demand for effective elimination strategies. Herein, we developed a new indole derivative decorated with a hexadecane chain and a tertiary amine center (named di-indole hexadecyl ammonium, DIHA), which can form stable nanospheres (100-200 nm) in water via supramolecular assembly. As the DIHA nanospheres can induce electrostatic, hydrophobic and van der Waals interactions (all are long-ranged) that operative cooperatively, in addition to the nano-sized particles with large surface area, the DIHA nanocomposite exhibited extremely fast adsorption rates (in seconds), high adsorption capacities (0.764-0.857 g g^-1) and selective adsorption for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), outperformed the previous reported high-end PFASs adsorbents. Simultaneously, the DIHA nanospheres can produce hydrated electron (e_aq^-) when subjected to UV irradiation, with the virtue of constraining the photo-generated e_aq^- and the adsorbed PFOA/PFOS molecules entirely inside the nanocomposite. As such, the UV/DIHA system exhibits extremely high degradation/defluorination efficiency for PFOA/PFOS, even under ambient conditions, especially with the advantages of low chemical dosage requirement (μM level) and robust performance against environmental variables. Therefore, it is a new attempt of using supramolecular approach to construct an indole-based nanocomposite, which can elegantly combine adsorption and degradation functions. The novel DIHA nanoemulsion system would shed light on the treatment of PFAS-contaminated wastewater.

Joint toxicity mechanisms of binary emerging PFAS mixture on algae (Chlorella pyrenoidosa) at environmental concentration

Since traditional Per- and polyfluoroalkyl substances (PFAS) were banned in 2009 due to their bioaccumulation, persistence and biological toxicity, the emerging PFAS have been widely used as their substitutes and entered the aquatic environment in the form of mixtures. However, the joint toxicity mechanisms of these emerging PFAS mixtures to aquatic organisms remain largely unknown. Then, based on the testing of growth inhibition, cytotoxicity, photosynthesis and oxidative stress, and the toxicity mechanism of PFAS mixture (Perfluorobutane sulfonate and Perfluorobutane sulfonamide) to algae was explored using the Gene set enrichment analysis (GSEA). The results revealed that all three emerging PFAS treatments had a certain growth inhibitory effect on Chlorella pyrenoidosa (C. pyrenoidosa), but the toxicity of PFAS mixture was stronger than that of individual PFAS and showed a significant synergistic effect at environmental concentration. The joint toxicity mechanisms of binary PFAS mixture to C. pyrenoidosa were related to the damage of photosynthetic system, obstruction of ROS metabolism, and inhibition of DNA replication. Our findings are conductive to adding knowledge in understanding the joint toxicity mechanisms and provide a basis for assessing the environmental risk of emerging PFAS.

Non-target discovery of emerging PFAS homologues in Dagang Oilfield: Multimedia distribution and profiles in crude oil

Per- and polyfluoroalkyl substances (PFASs) are applied in oil exploitation activity. In this study, non-target and suspect target analyses with high-resolution mass spectrometry were used for identification of novel PFASs in the oilfield environment. A total of thirty-seven PFAS homologues belonging to eight classes were identified as level 4 or above, which partly explained the amount of potential unknown PFAS-precursors that were indicated by total oxidisable precursor assay in our previous study. Hydrogen-substituted and ether-substituted homologues were the main identified PFASs, and seven of them were newly reported homologues. C1-C3 perfluoroalkane sulphonic acids (PFSAs) were also for the first time identified in the oilfield. The sediment-water partitioning coefficients of most identified PFAS homologues positively correlate with their predicted octanol-water partitioning coefficients while those of C1-C3 PFSAs may have elevated sediment partitioning potential as also previously observed for ultra-short chain C2-C3 perfluoroalkyl carboxylic acids. The crude oil and sludge samples were further examined with the target and identified PFAS profiles. An annual flux of 10.4 kg/y via oil production was estimated in Dagang Oilfield with 16.6 % not from the target PFASs. This demonstrates that oil exploitation activities can be a significant underlying source of PFASs to the environment.

Effect of perfluoroalkyl exposure in pregnancy and infancy on intrauterine and childhood growth and anthropometry. Sub study from COPSAC2010 birth cohort

BACKGROUND

Perfluoroalkyl substances PFOS and PFOA are persistent and bioaccumulative exogenous chemicals in the human body with a range of suspected negative health effects. It is hypothesised that exposure during prenatal and early postnatal life might have particularly detrimental effects on intrauterine and childhood growth. In a Danish longitudinal mother-child cohort we investigate effect of PFOS and PFOA in pregnancy and infancy on intrauterine and childhood growth and anthropometry.

METHODS

COPSAC₂₀₁₀ is an ongoing population based mother-child cohort of 738 pregnant women and their children followed from 24 week gestation with longitudinal deep clinical phenotyping until age 10 years. In this observational cohort sub study plasma PFOS and PFOA concentrations were semi-quantified by untargeted metabolomics in the mothers at week 24 and 1 week postpartum and in the children at ages 6 and 18 months and calibrated using a targeted pipeline. We examined associations to intrauterine and childhood growth and anthropometry, including interactions with child sex. Untargeted and targeted blood metabolomics profiles were integrated to investigate underlying mechanisms.

FINDINGS

Pregnancy plasma PFOA concentrations were associated with lower birth size -0.19 [-0.33; -0.05] BMI z-score per 1-ng/mL and increased childhood height (z-scored) at age 6: 0.18 [0.05; 0.31], but there was no association between childs' own infancy plasma PFOA concentration and height. Pregnancy plasma PFOS concentrations were also associated with lower birth BMI (-0.04 [-0.08; -0.01]), but in childhood pregnancy plasma PFOS concentration interacted with child sex on BMI and fat percentage at 6 years with negative associations in girls and positive in boys. The effect of maternal plasma PFOS concentration on lower girl BMI was borderline mediated through increasing child plasma lactosyl-ceramide levels (p-mediation=0.08). Similarly the effect of maternal plasma PFOS concentration on higher boy fat percentage was borderline mediated through increasing child plasma lactosyl-ceramide levels (p-mediation=0.07). Infancy concentrations of plasma PFOS associated with lower height in childhood, -0.06 z-score at age 6 [-0.19; -0.03].

INTERPRETATION

Higher PFOS and PFOA plasma concentrations during pregnancy had detrimental effects on fetal growth. The effects on childhood growth were not similar as PFOA increased child height, opposite of PFOS in multipollutant models suggesting a differing fetal programming effect. Sex specific growth effects were borderline mediated through an altered lactosyl-ceramide metabolism, proposing a possible mechanism of PFOS that has long-lasting health consequences in this observational study.

FUNDING

All funding received by COPSAC are listed on www.copsac.com. The Lundbeck Foundation (Grant no R16-A1694); The Novo Nordic Foundation (Grant nos NNF20OC0061029, NNF170C0025014, NNF180C0031764) The Ministry of Health (Grant no 903516); Danish Council for Strategic Research (Grant no 0603-00280B) and The Capital Region Research Foundation have provided core support to the COPSAC research center. Effort from JALS is supported by R01HL123915, R01HL141826, and R01HL155742 from NIH/NHLBI. CEW was supported by the Swedish Heart Lung Foundation (HLF 20180290, HLF 20200693). BC has received funding for this project from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. 946228). The funding agencies did not have any role in design and conduct of the study; collection, management, and interpretation of the data; or preparation, review, or approval of the manuscript.

Developing innovative treatment technologies for PFAS-containing wastes

The release of persistent per- and polyfluoroalkyl substances (PFAS) into the environment is a major concern for the United States Environmental Protection Agency (U.S. EPA). To complement its ongoing research efforts addressing PFAS contamination, the U.S. EPA's Office of Research and Development (ORD) commissioned the PFAS Innovative Treatment Team (PITT) to provide new perspectives on treatment and disposal of high priority PFAS-containing wastes. During its six-month tenure, the team was charged with identifying and developing promising solutions to destroy PFAS. The PITT examined emerging technologies for PFAS waste treatment and selected four technologies for further investigation. These technologies included mechanochemical treatment, electrochemical oxidation, gasification and pyrolysis, and supercritical water oxidation. This paper highlights these four technologies and discusses their prospects and the development needed before potentially becoming available solutions to address PFAS-contaminated waste.Implications: This paper examines four novel, non-combustion technologies or applications for the treatment of persistent per- and polyfluoroalkyl substances (PFAS) wastes. These technologies are introduced to the reader along with their current state of development and areas for further development. This information will be useful for developers, policy makers, and facility managers that are facing increasing issues with disposal of PFAS wastes.

Effects of perfluoroalkyl substances on soil respiration and enzymatic activity: differences in carbon chain-length dependence

Perfluoroalkyl substances (PFASs) are anthropogenic compounds that exhibit ecotoxicity when discharged into the environment, causing increasing concern. An indoor experiment was conducted to investigate the effects of perfluoroalkyl carboxylic acids (PFCAs) and PFSAs on soil respiration, sucrase activity, and urease activity at 0, 7, 14, and 28 d for perfluorooctanoic acid (PFOA), perfluorohexanoic acid (PFHxA), and perfluorobutyric acid (PFBA), and at 14 and 28 d for perfluorooctane sulfonic acid (PFOS), perfluorohexanoic sulfonic acid (PFHxS), and perfluorobutyric sulfonic acid (PFBS). PFCAs significantly inhibited soil respiration, with a significant negative correlation between respiration and PFBA (P < 0.05) at 28 d. Sucrase activities were initially inhibited by PFCAs, and then recovered. Urease activities were inhibited by PFOA at 14 d and by PFHxA at 14 and 28 d, but not by PFBA. PFOS and PFBS briefly enhanced soil respiration. PFOS inhibited sucrase activity. PFSAs significantly decreased urease activity in a concentration- and time-dependent manner. The chain-length dependence of the ecotoxicity of PFASs varied depending on concentration and time. Toxicity demonstrated a trend of initial decrease followed by increase with carbon chain length. Our results first revealed that the chain-length dependences of PFASs were also related to concentrations and exposure time.

Overview of the development of slippery surfaces: Lubricants from presence to absence

The superhydrophobic surfaces inspired by the lotus have excellent performances and are known for their low contact angle hysteresis and smooth surfaces. However, there are still some problems, such as the unstable structure, poor durability, high product cost and so on that need to be improved. Those issues can be avoided via liquid-infused surfaces(LIS), which are inspired by Nepenthes and consist of a mico-nano structured substrate and a smooth continuous atomic-grade lubricant. Compared with superhydrophobic surfaces, LIS not only achieves the same hydrophobic properties but also has smaller contact angle hysteresis, smoother surface, more stable structure and lower preparation cost. Although the existence of a lubricant layer improves the performance of the material, it also leaves a hidden danger, which is easy to lose and leads to the deterioration of the durability of the material. Therefore, the lubricant-free slipper materials have attracted more and more attention in recent years due to their low volatility, good durability and excellent lubrication performance. In this review, the types of LIS lubricants and their physicochemical properties were summarized at the beginning and then the applications of LIS in various fields were introduced. At the end of this paper, some solid lubricants and their applications were described, and the future development prospects of LIS lubricants also were expected.

Prenatal Exposure to Nonpersistent Chemical Mixtures and Offspring IQ and Emotional and Behavioral Problems

Prenatal exposure to nonpersistent chemicals such as phthalates, bisphenols, and organophosphate (OP) pesticides is ubiquitous and occurs in mixtures. So far, epidemiological studies investigating neurodevelopmental consequences of these exposures have mainly been restricted to single-pollutant models. Thus, we studied the association between prenatal exposure to nonpersistent chemical mixtures and child IQ and emotional and behavioral problems. Data came from 782 mother-child pairs. Eleven phthalate, one bisphenol, and five OP pesticide urinary exposure biomarkers were measured three times during pregnancy and averaged. Nonverbal IQ, internalizing and attention problems, aggressive behavior, and autistic traits were assessed at child age 6 years. We used quantile g-computation to estimate the change in each outcome per quartile increase in all chemicals within the mixture. Higher exposure to the mixture was associated with lower nonverbal IQ (-4.0 points (95%CI = -7.0, -1.0), -5.5 points (95%CI = -10.2, -0.9), and -4.6 points (95%CI = -10.8, 1.5) for the second, third, and fourth quartile, respectively, compared to the first quartile). These results were mainly driven by the phthalate mixture. No association was observed with emotional and behavioral problems. Prenatal exposure to nonpersistent chemical mixtures was associated with lower nonverbal IQ in children. Exposure to chemical mixtures during gestation is universal and may impact neurodevelopment.

Serum perfluoroalkyl substances and breast cancer risk in Japanese women: A case-control study

BACKGROUND

Perfluoroalkyl substances (PFASs) may contribute to causing breast cancer; however, associations between exposure to PFASs and risk of breast cancer are controversial.

OBJECTIVES

In the present study, we newly distinguished branched isomers of PFASs from their linear isomers and aimed to investigate the association between serum PFAS concentrations and breast cancer risk in Japanese women.

METHODS

We used a case-control design to study 405 eligible matched pairs attending four hospitals in Nagano Prefecture, Japan from May 2001 to September 2005. We used in-port arylation gas-chromatography mass spectrometry with negative chemical ionization to measure serum concentrations of 20 PFAS congeners. We calculated multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of breast cancer and its hormone-receptor subtypes by quartiles or tertiles of serum PFASs.

RESULTS

After multivariable adjustment for breast cancer risk factors, we found that serum concentrations of 20 PFAS congeners were significantly inversely associated with risk of breast cancer. Comparing the extreme quartiles of linear isomers of perfluorooctane sulfonate or perfluorooctanoic acid, ORs were 0.15 (95% CI: 0.07, 0.33 P for trend <0.0001) and 0.21 95% CI: 0.10, 0.44 P for trend <0.0001). Among postmenopausal women, whereas we found the linear isomer of perfluorotridecanoic acid to be inversely associated with breast cancer risk, a medium degree of exposure to the branched isomer of perfluorotridecanoic acid was associated with a marginally increased risk of breast cancer (OR [95% CI] = 1.74 [0.98, 3.09]).

DISCUSSION

In our case-control study, we found overall no association between serum PFAS concentrations and increased risk of breast cancer. Many inverse associations between serum PFAS concentrations and breast cancer risk were found.

The impact of perfluoroalkyl substances on pregnancy, birth outcomes and offspring development: A review of data from mouse models1

Per- and polyfluoroalkyl substances (PFASs) such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are persistent in the environment and bioaccumulate in wildlife and humans, potentially causing adverse health effects at all stages of life. Studies from human pregnancy have shown that exposure to these contaminants are associated with placental dysfunction and fetal growth restriction; however, studies in humans are confounded by genetic and environmental factors. Here, we synthesize the available results from mouse models of pregnancy to show the causal effects of prenatal exposure to PFOA and PFOS on placental and fetal development and on neurocognitive function and metabolic disorders in offspring. We also propose gaps in the present knowledge and provide suggestions for future research studies.

Anti-oxidant mechanisms of Chlorella pyrenoidosa under acute GenX exposure

GenX, a substitute for perfluorooctanoic acid, has been widely detected in surface water. Due to its bioaccumulation, toxicity and persistence, GenX can cause adverse effects such as oxidative damage on aquatic organisms. To investigate the toxicity of GenX and the anti-oxidant mechanism of algae under acute exposure, the growth, photosynthetic activity and gene expression of Chlorella pyrenoidosa (C. pyrenoidosa) were tested. Results showed that the growth of C. pyrenoidosa was inhibited under acute GenX exposure. The toxicity of GenX increased with time and concentration but was lower than that of the traditional perfluoroalkyl and polyfluoroalkyl substances (PFASs). Furthermore, with the increase of GenX concentration, the production of reactive oxygen species increased, while the level of the anti-oxidant enzyme first increased and then decreased. Changes in photosynthetic parameters also indicated that the photosynthetic system of C. pyrenoidosa was negatively affected by GenX exposure. Transcription analysis revealed that the up-regulation of genes related to the glutathione-ascorbate cycle and photosynthesis is a positive strategy to cope with the oxidative stress caused by acute GenX exposure. Our findings provide new insights into the interactions between emerging PFASs and aquatic organisms at the molecular level.

Design and synthesis of fluorinated peptides for analysis of fluorous effects on the interconversion of polyproline helices

The unique interaction between fluorine atoms has been exploited to alter protein structures and to develop synthetic and analytical applications. To expand such fluorous interaction for novel applications, polyproline peptides represent an excellent molecular nanoscaffold for controlling the presentation of perfluoroalkyl groups on their unique secondary structure. We develop approaches to synthesis fluorinated peptides to systematically investigate how the number, location and types of the fluorous groups on polyproline affect the conformation by monitoring the transition between the two major polyproline structures PPI and PPII. This work provides valuable information on how fluorous interaction affects the peptide structure and also benefits the design of functional fluorous molecules.

Occurrence, profiles, and ecotoxicity of poly- and perfluoroalkyl substances and their alternatives in global apex predators: A critical review

Certain poly- and perfluoroalkyl substances (PFASs) exhibit significant bioaccumulation/biomagnification behaviors in ecosystems. PFASs, such as perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorohexanesulfonic acid (PFHxS) and related precursors, have elicited attention from both public and national regulatory agencies, which has resulted in worldwide restrictions on their production and use. Apex predators occupy the top trophic positions in ecosystems and are most affected by the biomagnification behavior of PFASs. Meanwhile, the long lifespans of apex predators also lead to the high body burden of PFASs. The high body burden of PFASs might be linked to adverse health effects and even pose a potential threat to their reproduction. As seen in previous reviews of PFASs, knowledge is lacking between the current stage of the PFAS body burden and related effects in apex predators. This review summarized PFAS occurrence in global apex predators, including information on the geographic distribution, levels, profiles, and tissue distribution, and discussed the trophic transfer and ecotoxicity of PFASs. In the case where legacy PFASs were restricted under international convention, the occurrence of novel PFASs, such as 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) and perfluoroethylcyclohexane sulfonate (PFECHS), in apex predators arose as an emerging issue. Future studies should develop an effective analytical method and focus on the toxicity and trophic transfer behavior of novel PFASs.

Energy-efficient removal of PFOA and PFOS in water using electrocoagulation with an air-cathode

Electrocoagulation (EC) with a zinc anode demonstrated promising results to remove perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) from an aqueous solution. However, the energy requirement for EC is usually very high due to water electrolysis or aeration. This study aims to reduce energy consumption using an air-cathode in EC (ACEC) to supply oxygen electron acceptor without aeration for attenuating PFOA/PFOS in this new configuration. For the high PFOA concentration (0.25 mM), ACEC with 45 min of the reaction time exhibited an excellent PFOA removal (99.8 ± 0.3% removal) comparable to an EC with aeration (EC-aeration, 100% removal) while achieving much less energy consumption (0.14 kWh/m³). For the low PFOA concentration (0.1 μM), only 41.1 ± 11.6% was removed by the ACEC due to the low concentration gradient for adsorption. EC-aeration achieved higher PFOA removal (81.9 ± 15.1%) for the low PFOA concentration, possibly because air bubbles floated PFOA to the water surface, thereby concentrating PFOA. The PFOS removals in the ACEC and EC-aeration (76.4-88.5%) at the high concentration (0.25 mM) were lower than PFOA due tentatively to its micelle formation. However, PFOS was removed better than PFOA at the low concentration (0.1 μM) due to its higher hydrophobicity.

Black Tea Quality is Highly Affected during Processing by its Leaf Surface Microbiome

Microbiomes can greatly affect the quality of fermented food and beverages, including tea. In this study, microbial populations were characterized during black and green tea manufacturing, revealing that tea processing steps can drive both the bacterial and fungal community structure. Tea leaves were found to mostly harbor Proteobacteria, Bacteriodetes, Firmicutes, and Actinobacteria among bacteria and Ascomycetes among fungi. During processing, tea microbial populations changed especially between sterilized and unsterilized samples. The surface sterilization of fresh leaves before processing can remove many microbes, especially the bacteria of the genera Sphingomonas and Methylobacteria, indicating that these are mostly phylloplane microbes on tea leaves. The surface sterilization removed most fungi, except the Debaryomyces. We also observed a fluctuation in the content of several tea quality-related metabolites during processing. Caffeine and theanine were found in the same quantities in green tea with or without leaf surface sterilization. However, the sterilization process dramatically decreased the content of total catechins and theanine in black tea, indicating that microbes on the surface of tea leaf may be involved in maintaining the formation of these important metabolites during black tea processing.

Chemical Aspects of Human and Environmental Overload with Fluorine

Over the last 100-120 years, due to the ever-increasing importance of fluorine-containing compounds in modern technology and daily life, the explosive development of the fluorochemical industry led to an enormous increase of emission of fluoride ions into the biosphere. This made it more and more important to understand the biological activities, metabolism, degradation, and possible environmental hazards of such substances. This comprehensive and critical review focuses on the effects of fluoride ions and organofluorine compounds (mainly pharmaceuticals and agrochemicals) on human health and the environment. To give a better overview, various connected topics are also discussed: reasons and trends of the advance of fluorine-containing pharmaceuticals and agrochemicals, metabolism of fluorinated drugs, withdrawn fluorinated drugs, natural sources of organic and inorganic fluorine compounds in the environment (including the biosphere), sources of fluoride intake, and finally biomarkers of fluoride exposure.

Monitoring Analysis of Perfluoroalkyl Substances and F-53B in Bottled Water, Tea and Juice Samples by LC-MS/MS

Monitoring analysis of 14 per- and polyfluoroalkyl substances (PFAS), 9-chlorohexadecafluoro-3-oxanonane-1-sulfonate (F-53B) and dodecafluoro-3H-4,8-dioxanonanoate (ADONA) in bottled drinking water, tea and juice samples was performed using LC coupled with tandem mass spectrometry (LC-MS/MS) and solid-phase extraction (SPE). In the electrospray negative ion mode, the limit of detection and limit of quantification (LOQ) values were 0.1 to 0.8 ng/mL and 0.2 to 1.6 ng/mL, respectively. The calibration curves were linear from LOQ to 50 ng/mL (r² > 0.999). The SPE procedure (Presep PFC-II) was utilized for sample preparation and recovery rates for three standards (35, 70 and 140 ng/L) were 80.4-118.8% with relative standard deviation (RSD) ≤ 0.6%. Using the developed method, various samples (n = 54) from Japanese markets were investigated for PFAS and F-53B contamination, and values below the LOQ were observed. It is concluded that for monitoring products in the Japanese market, our method represents a significant improvement over complex techniques for the quantification of PFAS and related compounds from various foods.

Analyzing extended STIRPAT model of urbanization and CO2 emissions in Asian countries

CO₂ emissions tend to increase more rapidly in underdeveloped economies as compared to developed countries mainly in China, India, and Asia. One of the aspects that accounts for the increasing CO₂ emissions is urbanization (UR) and it is increasing all over the world particularly in Asian and African regions. The present study examines the impact of energy use and UR on carbon emissions over the period 1995 to 2018 while using the extended STIRPAT model for Asian countries. Panel co-integration techniques and Granger causality test are applied on selected variables. FMOLS and DOLS methods are also applied to check for robustness. Findings confirm the presence of long-run co-integration among variables. The outcomes propose that energy consumption and UR have positive impact on CO₂ emissions and output. Outcomes also reveal that financial development (FD) has negative effect on emissions of CO₂ but positive effect on economic growth. Results of Granger causality technique indicate that long-run causality association exists among emissions of CO₂, economic growth, and UR. In the short run (SR), bidirectional causal relationship has been found between trade openness and FD.

Comparison of extraction methods for per- and polyfluoroalkyl substances (PFAS) in human serum and placenta samples-insights into extractable organic fluorine (EOF)

Since the detection of per- and polyfluoroalkyl substances (PFAS) in humans and different environmental media in the last two decades, this substance group has attracted a lot of attention as well as increasing concerns. The fluorine mass balance approach, by comparing the levels of targeted PFAS after conversion to fluorine equivalents with those of extractable organic fluorine (EOF), showed the presence of unidentified organofluorine in different environmental samples. Out of the thousands of PFAS in existence, only a very small fraction is included in routine analysis. In recent years, liquid chromatography coupled with tandem-mass spectrometry (LC-MS/MS) has demonstrated the ability to analytically cover a wide spectrum of PFAS. In contrast, conventional extraction methods developed 10 to 15 years ago were only evaluated for a limited number of PFAS. The aim of the present study was to evaluate the advantages and disadvantages of three different extraction methods, adapted from the literatures without further optimization (ion-pair liquid-liquid extraction, solid-phase extraction (SPE), using hydrophilic-lipophilic (HLB) or weak anion exchange (WAX) sorbents), for human biomonitoring of 61 PFAS in serum and placental tissue samples. In addition, levels of EOF were compared among these extraction methods via spiked samples. Results showed that performance, in terms of recovery, differed between the extraction methods for different PFAS; different extraction methods resulted in different EOF concentrations indicating that the choice of extraction method is important for target PFAS and EOF analysis. Results of maternal serum samples, analyzed in two different laboratories using two different extraction methods, showed an accordance of 107.6% (± 21.3); the detected perfluoroalkyl acids (PFAAs) in maternal and cord serum samples were in the range of 0.076 to 2.9 ng/mL.

Graphical abstract

Formation and In Situ Treatment of High Fluoride Concentrations in Shallow Groundwater of a Semi-Arid Region: Jiaolai Basin, China

Fluorine is an essential nutrient, and excessive or deficient fluoride contents in water can be harmful to human health. The shallow groundwater of the Jiaolai Basin, China has a high fluoride content. This study aimed to (1) investigate the processes responsible for the formation of shallow high-fluoride groundwater (SHFGW); (2) identify appropriate methods for in situ treatment of SHFGW. A field investigation into the formation of SHFGW was conducted, and the results of experiments using soils from high-fluoride areas were examined to investigate the leaching and migration of fluoride. The results showed that the formation of SHFGW in the Jiaolai Basin is due to long-term geological and evaporation processes in the region. Stratums around and inside the basin act as the source of fluoride whereas the terrain promotes groundwater convergence. The hydrodynamic and hydrochemical conditions resulting from slow groundwater flow along with high evaporation and low rainfall all contribute to the enrichment of fluoride in groundwater. In situ treatment of SHFGW may be an effective approach to manage high SHFGW in the Jiaolai Basin. Since soil fluoride in high-fluoride areas can leach into groundwater and migrate with runoff, the construction of ditches can shorten the runoff of shallow groundwater and accelerate groundwater loss, resulting in the loss of SHFGW from high-fluoride areas through river outflow. The groundwater level will be reduced, thereby lowering the influence of evaporation on fluoride enrichment in shallow groundwater. The results of this study can act a reference for further research on in situ treatment for high-fluoride groundwater.

Toward Sustainable Environmental Quality: Priority Research Questions for Asia

Environmental and human health challenges are pronounced in Asia, an exceptionally diverse and complex region where influences of global megatrends are extensive and numerous stresses to environmental quality exist. Identifying priorities necessary to engage grand challenges can be facilitated through horizon scanning exercises, and to this end we identified and examined 23 priority research questions needed to advance toward more sustainable environmental quality in Asia, as part of the Global Horizon Scanning Project. Advances in environmental toxicology, environmental chemistry, biological monitoring, and risk-assessment methodologies are necessary to address the adverse impacts of environmental stressors on ecosystem services and biodiversity, with Asia being home to numerous biodiversity hotspots. Intersections of the food-energy-water nexus are profound in Asia; innovative and aggressive technologies are necessary to provide clean water, ensure food safety, and stimulate energy efficiency, while improving ecological integrity and addressing legacy and emerging threats to public health and the environment, particularly with increased aquaculture production. Asia is the largest chemical-producing continent globally. Accordingly, sustainable and green chemistry and engineering present decided opportunities to stimulate innovation and realize a number of the United Nations Sustainable Development Goals. Engaging the priority research questions identified herein will require transdisciplinary coordination through existing and nontraditional partnerships within and among countries and sectors. Answering these questions will not be easy but is necessary to achieve more sustainable environmental quality in Asia. Environ Toxicol Chem 2020;39:1485-1505. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Nontargeted mass-spectral detection of chloroperfluoropolyether carboxylates in New Jersey soils

The toxicity and environmental persistence of anthropogenic per- and poly-fluoroalkyl substances (PFAS) are of global concern. To address legacy PFAS concerns in the United States, industry developed numerous replacement PFAS that commonly are treated as confidential information. To investigate the distribution of PFAS in New Jersey, soils collected from across the state were subjected to nontargeted mass-spectral analyses. Ten chloroperfluoropolyether carboxylates were tentatively identified, with at least three congeners in all samples. Nine congeners are ≥(CF2)7 Distinct chemical formulas and structures, as well as geographic distribution, suggest airborne transport from an industrial source. Lighter congeners dispersed more widely than heavier congeners, with the most widely dispersed detected in an in-stock New Hampshire sample. Additional data were used to develop a legacy-PFAS fingerprint for historical PFAS sources in New Jersey.

Be cautious applying carbon-fluorine bonds in drug delivery

As reported in Chemosphere by Colles et al. (2020), there are multiple pathways for human exposure to poly- and perfluoroalkyl substances (PFAS). Now, a new chemical formation of C-F bonds in drug delivery lead to concerns for human exposure as these inert chemical formations are resistance to metabolic degradation and excretion.

Ion chromatography for monitoring [NTf2]- anion contaminants in pure and saline water

Hydrophobic ionic liquids containing bis(trifluoromethanesulfonyl)imide, [NTf2]-, anions partially dissolve in aqueous phases. The potential ecotoxicity of [NTf2]- means wastewater streams must be closely monitored to avoid environmental release. A new ion chromatography method is presented, which improves on existing techniques and methods by significantly decreasing analysis time and improving chromatographic peak properties. Consequently, the limit of detection is lowered to 5 μM (1.4 ppm) and limit of quantification lowered to 30 μM (8.5 ppm). The method is reproducible and has a high precision for short and medium chain length ionic liquids (RSD = 0.95%); however, microemulsion effects increase measurement errors for long chain ionic liquids (RSD = 2.32%), albeit by a relatively small amount. Hence, the method is a highly accurate analytical method for highly polarizable [NTf2]- anions, and quantification in the presence of high salinity samples, such as seawater, is readily achieved. Importantly, this method is a significant improvement on existing techniques (chromatography, NMR, UV-Vis) for many reasons, making it ideal for environmental monitoring or process design of [NTf2]- ionic liquid-based applications.

Molecular Aggregation Structure and Surface Properties of Biomimetic Catechol-Bearing Poly[2-(perfluorooctyl)ethyl acrylate] and Its Application to Superamphiphobic Coatings

The molecular aggregation structure and surface properties of a catechol-bearing fluoropolymer, P(FAC8-co-DOPAm), which was synthesized by conventional radical copolymerization of 2-(perfluorooctyl)ethyl acrylate (FAC8) and N-(3,4-dihydroxyphenethyl)acrylamide (DOPAm), and its application to the superamphiphobic surfaces are presented. The crystallinity of P(FAC8-co-DOPAm) was lower than that of poly[2-(perfluorooctyl)ethyl acrylate] (PFAC8). The perfluoroalkyl (Rf) groups were ordered on the surface with CF3 terminals exposed to air, and the Rf ordering was influenced by thermal history: the thermally annealed film exhibited higher Rf ordering than the unannealed one. The surface free energy was estimated to be γ = 7.32 mJ m-2 for both the unannealed and annealed films. Based on contact angle measurement, various interfacial structures of water and oils in accordance with the surface aggregation structure of Rf groups were proposed. Dewetting of the PFAC8 film at elevated temperature was suppressed by the introduction of catechol groups in the backbone. The degradation temperature of PFAC8 was improved significantly, and the evaporation of the low molar mass-polymer was inhibited by the introduction of catechol groups under both nitrogen and air atmospheres. The hydrophobicity of the copolymer films could be healed after the surface was damaged by vacuum ultraviolet (VUV) irradiation. This copolymer was used to create superamphiphobic fabrics and halloysite nanotube (HNT)-based organic/inorganic hybrid coatings successfully. Wetting behaviors of the superamphiphobic fabrics and coatings both follow the Cassie-Baxter wetting model.

Nontarget Discovery of Per- and Polyfluoroalkyl Substances in Atmospheric Particulate Matter and Gaseous Phase Using Cryogenic Air Sampler

Novel per- and polyfluoroalkyl substances (PFASs) have become a key issue in global environmental studies. Although several novel PFASs have been discovered in atmospheric particulate matter through nontarget analysis, information on the environmental occurrence of novel PFASs in atmospheric gaseous phases and conventional sampling techniques is somewhat deficient. Therefore, this Article describes a new type of air sampler, the cryogenic air sampler (CAS), which was used to collect all atmospheric components simultaneously. Nontarget analysis then was performed through PFASs homologue analysis. A total of 117 PFAS homologues (38 classes) were discovered, 48 of which (13 classes) were identified with confidence Level 4 or above. Eleven chlorinated perfluoropolyether alcohols (3 classes) and four chlorinated perfluoropolyether carboxylic acids (2 classes) have been reported for the first time in this Article. This Article is also the first report of 12 hydrosubstituted perfluoroalkyl carboxylates (H-PFCAs) in the atmosphere. H-PFCAs and chlorinated perfluoropolyether carboxylic acids were mainly distributed in the particular phase. These results are evidence that novel chlorinated polyether PFASs should be the focus of future study.

Fluoropolymer Nanoparticles Prepared Using Trifluoropropene Telomer Based Fluorosurfactants

A fluorosurfactant based on 3,3,3-trifluoropropene (TFP) telomer was synthesized as an environmentally friendly alternative to perfluorooctanoic acid (PFOA) using TFP and 2-iodoperfluoropropane ((CF₃)₂CF-I) as starting materials. TFP telomerization was initiated by addition of di-tert-butylperoxide in the presence of (CF₃)₂CF-I as a chain transfer agent. The surfactant was obtained by modification of the iodine end-group on the TFP telomer to form an allylic functionality followed by the addition of thioglycolic acid via a thiol-ene reaction. The resulting fluorosurfactant exhibited a lower critical micellar concentration (CMC = 0.87 g·L^-1) than that of PFOA (CMC = 3.0 g·L^-1). This surfactant was used to prepare fluoropolymer nanoparticles by solvent evaporation from a solution composed of the surfacant and poly[2-(perfluorobutyl)ethyl methacrylate]. The oil-in-water emulsion was initially formed due to the adsorption of the surfactant molecules at the oil/water interface and subsequently converted into a nanoparticle suspension after solvent evaporation. Because of the strong hydrophobic interactions between the fluorinated surfactant tail and fluoropolymer, the obtained nanoparticle suspension was quite stable against water dialysis.