Suspect and Nontarget Screening Revealed Class-Specific Temporal Trends (2000-2017) of Poly- and Perfluoroalkyl Substances in St. Lawrence Beluga Whales

Legacy and emerging per- and polyfluoroalkyl substances in eggs of yellow-legged gulls from Southern France

More than 70 years of industrial production of per- and polyfluoroalkyl substances (PFAS) have resulted in their ubiquitous presence in the environment on a global scale, although differences in sources, transport and fate lead to variability of occurrence in the environment. Gull eggs are excellent bioindicators of environmental pollution, especially for persistent organic pollutants such as PFAS, known to bioaccumulate in organisms and to be deposited in bird eggs by maternal transfer. Using yellow-legged gull (Larus michahellis) eggs, we investigated the occurrence of more than 30 PFAS, including the most common chemicals (i.e., legacy PFAS) as well as their alternatives (i.e., emerging PFAS) in the Bay of Marseille, the second largest city in France. Compared to eggs from other colonies along the Mediterranean coast, those from Marseille had PFAS concentrations ranging from slightly higher to up to four times lower, suggesting that this area cannot be specifically identified as a hotspot for these compounds. We also found several emerging PFAS including 8:2 and 10:2 FTS, 7:3 FTCA or PFECHS in all collected eggs. Although the scarcity in toxicity thresholds for seabirds, especially during embryogenesis, does not enable any precise statement about the risks faced by this population, this study contributes to the effort in documenting legacy PFAS contamination on Mediterranean coasts while providing valuable novel inputs on PFAS of emerging concern. Identifying exposure in free-ranging species also participate to determine the main target for toxicity testing in wildlife.

HFPO-DA and Other PFAS in Air Downwind of a Fluoropolymer Production Plant in the Netherlands: Measurements and Modeling

Emissions of historical fluorinated processing aids used in fluoropolymer production are known to have contributed significantly to environmental levels of persistent perfluoroalkyl acids (PFAAs). Less is known about emissions of contemporary processing aids and the efficacy of technology used to contain them. To address this, we investigated the occurrence of hexafluoropropylene oxide dimer acid (HFPO-DA) and other per- and polyfluoroalkyl substances (PFAS) in airborne PM10 near a fluoropolymer production plant in the Netherlands. The 20-week high-volume air sampling campaign coincided with installation of emission abatement systems. HFPO-DA levels ranged from below detection limits to 98.66 pg m-3 when the wind came from the plant, and decreased to a maximum of 12.21 pg m-3 postabatement. Lagrangian dispersion modeling using FLEXPART revealed good concordance between measured and modeled HFPO-DA concentrations (Pearson's r = 0.83, p ≤ 0.05, Wilmott's d = 0.71, mean absolute error = 3.66 pg m-3), providing further evidence that the plant is a point source. Modeling also suggested that HFPO-DA could undergo long-range atmospheric transport with detectable HFPO-DA air concentrations predicted up to several thousand kilometers away. Besides HFPO-DA, the fluorinated processing aid 6:2 fluorotelomer sulfonate and the suspected polymerization byproducts, hydrogen-substituted perfluoroalkyl carboxylic acids, were also observed, highlighting the complex mixture of PFAS emitted by the plant.

Per- and polyfluoroalkyl substances (PFAS) in drinking water systems in the lower Yangtze River: source, fate, and health risk assessment

The Yangtze River is significantly impacted by industrial activities related to per- and polyfluoroalkyl substances (PFAS) in China, posing potential threats to drinking water safety. So far, our knowledge of PFAS occurrence in the river and their fate in the whole drinking water supply systems remains limited. We conducted a comprehensive investigation of PFAS in Jiangsu's drinking water systems, using the target screening method. 12 perfluoroalkyl acids (PFAAs) and 7 emerging PFAS were detected and precisely quantified in the whole treatment process water flows, as well as source water and household tap water with concentrations of 61.34-90.40 ng/L. PFAAs [PFOA (30.26 ng/L), PFBS (23.25 ng/L), PFBA (18.82 ng/L) and PFHxA (16.89 ng/L)] and 8:8 PFPiA (13.63 ng/L) were the dominant pollutants in the low Yangtze River. PFBA (19.92 ng/L), PFBS (15.02 ng/L) and PFOA (11.94 ng/L) were major contaminants in tap water. The powder activated carbon pre-treatment in DWTP-B could remove 21.36-65.84% of long-chain PFAS, especially PFOA. Ozonation achieved slight emerging PFAS removal (3.22-11.06%), while PFAAs concentrations exhibited an increase. Granular active carbon filtration was effective in removing long-chain PFAS, with DWTP-B outperforming DWTP-A. PFSAs (3.12-22.09%) had a better removal than PFCAs (- 0.62 to 19.54%). Infants and children face a moderate health risk of PFAS intake through drinking water, peaking at the age group of 9 months to 1 year (HQ = 2.45). These findings underscore the necessity for improved PFAS removal technologies and stricter regulation of PFAS contamination in the Yangtze River to reduce exposure.

A re-assessment of archived (1989-2006) beluga liver from the North American Arctic with non-targeted analysis reveals brominated chemicals of emerging concern

In 2011, 68 archived beluga whale (Delphinapterus leucas) liver samples collected from Cook Inlet and the eastern Chukchi Sea from 1989 to 2006 were characterized for 12 per- and polyfluoroalkyl substances (PFAS) using targeted mass spectroscopy (MS) methods; however, at the time of the original analysis, high resolution MS (HRMS) methods were not readily available. This follow-up study utilizes both targeted as well as cutting-edge HRMS non-targeted analysis (NTA) techniques to screen for additional PFAS as well as potential contaminants of emerging concern (CECs) in the chemical space under investigation. Targeted analysis detected perfluorodecanesulfonic acid (PFDS) and perfluoroheptane sulfonic acid (PFHpS) in 10 % and 9 % of liver samples, respectively. PFDS detections were observed only in Cook Inlet whales while PFHpS was detected in whales from both locations. In addition, NTA identified four dibrominated pyrrole ring structures two with a sulfate (C8H11NBr2SO3, and C9H13NBr2SO3, Schymanski level 3), and two with either a sulfonate or a sulfate and hydroxy group (C8H11NBr2SO4, C9H13NBr2SO4, Schymanski level 4) in whales from the eastern Chukchi Sea. Literature search reveals similar brominated metabolites from marine bacteria, sponges, and other marine organisms, suggesting the brominated CECs are of marine origin.

Synthesis and Toxicity Evaluation of p-Phenylenediamine-Quinones

N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-Q), the tire rubber-derived transformation product of 6PPD, was recently discovered to cause the acute mortality of coho salmon (Oncorhynchus kisutch). Aiming to identify potential replacement antiozonants for 6PPD that do not produce toxic quinones, seven PPD-quinones with distinct side chains were synthesized to investigate their structure-related toxicities in vivo using rainbow trout (Oncorhynchus mykiss). While 6PPD-Q exerted high toxicity (96 h LC50 = 0.35 μg/L), toxicity was not observed for six other PPD-quinones despite their similar structures. The fish tissue concentrations of 6PPD-Q after sublethal exposure (0.29 μg/L) were comparable to the other PPD-quinones, which indicated that bioaccumulation levels were not the reason for the selective toxicity of 6PPD-Q. Hydroxylated PPD-quinones were detected as the predominant metabolites in fish tissue. Interestingly, a single major aromatic hydroxylation metabolite was detected for the alternate PPD-quinones, but two abundant OH-6PPD-Q isomers were detected for 6PPD-Q. MS2 spectra confirmed that hydroxylation occurred on the alkyl side chain for one isomer. The structurally selective toxicity of 6PPD-Q was also observed in a coho salmon (CSE-119) cell line, which further supports its intrinsic toxicity. This study reported the selective toxicity of 6PPD-Q and pinpointed the possibility for other PPDs to be applied as potential substitutes of 6PPD.

Emerging Per- and Polyfluoroalkyl Substances in Tap Water from the American Healthy Homes Survey II

Humans experience widespread exposure to anthropogenic per- and polyfluoroalkyl substances (PFAS) through various media, which can lead to a wide range of negative health impacts. Tap water is an important source of exposure in communities with any degree of contamination but routine or large-scale PFAS monitoring often depends on targeted analytical methods limited to measuring specific PFAS. We analyzed 680 tap water samples from the American Healthy Homes Survey II for PFAS using non-targeted analysis (NTA) to expand the range of detectable PFAS. Based on detection frequency and relative abundance, about half of the identified PFAS were found only by NTA. We identified (with varying degrees of confidence) 75 distinct PFAS, including 57 exclusively detected by NTA. The identified PFAS are members of seven structural subclasses differentiated by their head groups and degree of fluorination. Clustering analysis categorized the PFAS into four coabundance groups dominated by specific PFAS subclasses. One group uniquely identified by NTA contains zwitterionic PFAS and other PFAS transformation products which are likely associated with aqueous firefighting foam contaminants in a small number of spatially correlated samples. These results help further characterize the scope of exposure to emerging PFAS experienced by the U.S. population via tap water and augment nationwide targeted-PFAS monitoring programs.

Environmental Applications of Mass Spectrometry for Emerging Contaminants

Emerging contaminants (ECs), encompassing pharmaceuticals, personal care products, pesticides, and industrial chemicals, represent a growing threat to ecosystems and human health due to their persistence, bioaccumulation potential, and often-unknown toxicological profiles. Addressing these challenges necessitates advanced analytical tools capable of detecting and quantifying trace levels of ECs in complex environmental matrices. This review highlights the pivotal role of mass spectrometry (MS) in monitoring ECs, emphasizing its high sensitivity, specificity, and versatility across various techniques such as Gas Chromatography-Mass Spectrometry (GC-MS), Liquid Chromatography-Mass Spectrometry (LC-MS), and High-Resolution Mass Spectrometry (HR-MS). The application of MS has facilitated the real-time detection of volatile organic compounds, the comprehensive non-targeted screening of unknown contaminants, and accurate quantification in diverse matrices including water, soil, and air. Despite its effectiveness, challenges such as matrix interferences, a lack of standardized methodologies, and limited spectral libraries persist. However, recent advancements, including hybrid MS systems and the integration of artificial intelligence (AI), are paving the way for more efficient environmental monitoring and predictive modeling of contaminant behavior. Continued innovation in MS technologies and collaborative efforts are essential to overcome existing challenges and ensure sustainable solutions for mitigating the risks associated with emerging contaminants.

Two-layer homolog network approach for PFAS nontarget screening and retrospective data mining

The rapid increase of novel per- and polyfluoroalkyl substances (PFAS) raises concerns, while their identification remains challenging. Here, we develop a two-layer homolog network approach for PFAS nontarget screening using mass spectrometry. The first layer constructs networks between homologs, with evaluation showing that it filters 94% of false candidates. The second layer builds a network between classes to expedite the identification of PFAS. We detected 94 PFAS in twelve waterproof products and two related industrial sludges, including 36 novel PFAS not previously reported in any sample. A local dataset is constructed for retrospective analysis by re-analyzing our previous samples, revealing fifteen novel PFAS in samples collected in 2005. The retrieval of the public database MassIVE uncovers novel PFAS in samples from seven countries. Here, we reveal the historic and global presence of novel PFAS, providing guidance for the management and policy-making concerning persistent chemicals.

A systematic review for non-targeted analysis of per- and polyfluoroalkyl substances (PFAS)

This review follows the PRISMA guidelines to provide a systematic review of 115 peer reviewed articles that used non-targeted analysis (NTA) methods to detect per- and polyfluoroalkylated substances (PFAS). This literature highlights the significant positive impact of NTA in understanding PFAS in the environment. Within the literature a geographical bias exists, with most NTA studies (∼60 %) conducted in the United States and China. Future studies in other regions (such as South America and Africa) are needed to gain a more global understanding. More research is required in marine environments and the atmosphere, as current studies focus mainly on freshwater, groundwater, soil, and sediments. The majority of studies focus on measuring PFAS in the environment, rather than in commercial products (with the exception of AFFF). Non-lethal blood sampling has been successful for NTA in humans and wildlife, but additional biomonitoring studies are required on exposed cohorts to understand health risks and PFAS biotransformation pathways. NTA methods mostly use liquid chromatography and negative ionisation, which biases the literature towards the detection of specific PFAS. Despite improvements in data reporting and quality assurance and control (QA/QC) procedures, factors such as false negative and false positive rates are often overlooked, and many NTA workflows remain highly subjective. Perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs) are the most detected PFAS classes, identified in over 80 % of NTA studies, and are common in routine monitoring. However, our review identified >1000 PFAS from a total of 382 different PFAS classes, with over 300 classes found in fewer than 5 % of studies. This highlights the variety of different PFAS present in the environment, and the limitations of relying solely on targeted methods. Future monitoring programs and regulations would benefit from considering NTA methods to provide more comprehensive information on PFAS present in the environment.

Trends in extraction techniques for the determination of organic micropollutants in liver tissues of vertebrates

Determining organic micropollutants in liver samples of apex species is of foremost importance for biomonitoring studies, as it can provide evidence of environmental pollution and exposure of living organisms to chemicals. This review aims to provide a 4-year overview and summarize the trends in the extraction methodologies to determine both polar and non-polar organic micropollutants in liver samples from organisms of higher trophic levels. The dominant extraction techniques including ultrasound-assisted extraction (UAE), pressurized liquid extraction (PLE), Soxhlet, and QuEChERS, as well as additional steps and/or modifications applied in the reviewed studies, are presented and critically discussed. The latest trends in these methods as well as a comparison between them considering elapsed time, robustness, cost, and environmental fingerprint are also provided.

An extended PFAS profiling of a Swedish subpopulation and mixture risk assessments using multiple approaches

Per- and polyfluoroalkyl substances (PFAS) have been detected worldwide, from the deep seas to polar regions. A previous review showed that PFAS are risk drivers of the chemical mixture present in human blood. This study focused on establishing the PFAS exposure of a Swedish subpopulation and investigated whether the exposure poses a risk of adverse health effects. Human serum from 60 blood donors in Stockholm, Sweden, was analyzed. A target method including 32 PFAS analytes and over 270 suspect features was used to detect and quantify PFAS. Twenty-six PFAS were quantified, and 7 suspect PFAS features (6 H-PFCAs and PFECHS) were semi-quantified. Nine mixture risk assessment (MRA) strategies were used to assess the risk of health outcomes. Fifteen effect levels were derived and used, along with 15 already established values. The certainty of various derivation techniques was discussed. The MRAs showed that the entire studied population exceeded some of the risk thresholds, with effects including high cholesterol and immune suppression. However, the certainty was lower when deriving these two effect levels. The MRA, using human biomonitoring guidance values (high certainty), concluded that for 63 % of the individuals, a risk for adverse health effects cannot be excluded. This study has demonstrated that there is a reason for concern regarding PFAS exposure in the general population of Sweden. To our knowledge, this is the first time the H-PFCAs have been semi-quantified in human blood using a reference standard.

New Insights into Thermal Degradation Products of Long-Chain Per- and Polyfluoroalkyl Substances (PFAS) and Their Mineralization Enhancement Using Additives

The products of incomplete destruction (PIDs) of per- and polyfluoroalkyl substances (PFAS) represent a substantial ambiguity when employing thermal treatments to remediate PFAS-contaminated materials. In this study, we present new information on PIDs produced in both inert and oxidative environments from five long-chain PFAS, including three now regulated under the U.S. Safe Drinking Water Act, one cationic precursor compound, and one C10 PFAS. The data did not support the generation of tetrafluoromethane from any of the studied PFAS, and carbonyl fluoride was found only from potassium perfluorooctanesulfonate (K-PFOS) when heated in air in a narrow temperature range. Oxidative conditions (air) were observed to facilitate PFAS thermal degradation and accelerate the mineralization of K-PFOS. Spectroscopic data suggest that PFAS thermal degradation is initiated by the cleavage of bonds that form perfluoroalkyl radicals, leading to organofluorine PIDs (e.g., perfluoroalkenes). In air, perfluoroalkyl radicals react with oxygen to form oxygen-containing PIDs. The mineralization of PFAS was enhanced by adding solid additives, which were categorized as highly effective (e.g., granular activated carbon (GAC) and certain noble metals), moderately effective, and noneffective. Remarkably, simply by adding GAC, we achieved >90% mineralization of perfluorooctanoic acid at 300 °C and ∼1.9 atm within just 60 min without using water or solvents.

Structurally Selective Ozonolysis of p-Phenylenediamines and Toxicity in Coho Salmon and Rainbow Trout

The tire-rubber-derived ozonation product of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-Q), was recently discovered to cause acute mortality in coho salmon (Oncorhynchus kisutch). para-Phenylenediamines (PPDs) with variable side chains distinct from 6PPD have been identified as potential replacement antioxidants, but their toxicities remain unclear under environmentally relevant ozone conditions. We herein tested the multiphase gas-surface ozone reactivity of four select PPDs [6PPD, N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), N,N'-diphenyl-p-phenylenediamine (DPPD), and N-phenyl-N'-cyclohexyl-p-phenylenediamine (CPPD)] and evaluated the toxicity of their reaction mixtures in coho salmon, rainbow trout (Oncorhynchus mykiss), and fathead minnow (Pimephales promelas). 6PPD and IPPD were found to rapidly react with ozone, while no significant multiphase ozone reactivity was observed for DPPD or CPPD. The viability of coho salmon CSE-119 cells was strongly affected by the ozonolysis products of 6PPD but not by those of the other three PPDs. Acute mortality was only observed in juvenile rainbow trout that were exposed to oxidized 6PPD, suggesting a common mechanism of toxic action in the two salmonid fish species. This study reports the structurally selective ozone reactivity of PPDs and the unique toxicity of 6PPD ozonolysis mixtures, which demonstrates that other PPDs are potential alternative antioxidants.

Legacy and Novel Per- and Polyfluoroalkyl Substances in Surface Soils across China: Source Tracking and Main Drivers for the Spatial Variation

China aims to actively control the contamination of globally concerning per- and polyfluoroalkyl substances (PFASs). Evaluation of the current situation can provide a critical reference point for tracking the effectiveness of ongoing progress. Herein, we present the first comprehensive assessment of the spatial variations of 20 legacy and 54 novel PFASs in Chinese background soils in 2021. Novel PFASs were extensively detected in 98.4% of the samples, with 21 species being first reported, which greatly facilitated the appointment of diverse emission sources that aligned with local industrial structures. However, legacy PFASs still dominated the ∑74PFAS profile (median 0.51 ng/g, 0.050-8.33 ng/g). The spatial heterogeneity of soil PFASs was positively driven by economic development and atmospheric deposition, enabling the establishment of predictive models to project the national distribution and temporal trends. Elevated PFAS levels were predominantly distributed in the more industrialized eastern and southern regions, as well as other coastal areas with greater precipitation. ∑74PFAS in surface soils was estimated to increase by 12.9 pg/(g year) over 2002-2021, which would continue alongside economic growth, albeit with greater contributions from novel alternatives. Our work provides comprehensive baseline and predictive data to inform policies toward PFAS control in China.

Interrogation of a fluoropolymer dispersion manufactured with a non-fluorinated polymerization aid for targeted and non-targeted fluorinated residuals by liquid chromatography high resolution mass spectrometry

Recent advances in fluoropolymer polymerization have focused on replacing perfluorinated polymerization aids (PAs) with hydrocarbon-based alternatives. Hydrocarbon PAs are vulnerable to fluorinated radicals during polymerization, leading to the creation of hundreds of process-specific polyfluorinated residuals. These residuals, which include low molecular weight extractable or leachable impurities, are challenging to detect at trace levels. This study investigates a polytetrafluoroethylene (PTFE) dispersion prepared with a hydrocarbon-based surfactant (DOSS) to measure these process-specific fluorinated residues. Liquid chromatography high resolution mass spectrometry is one of the few analytical methods that offers the sensitivity and selectivity required to detect these residuals in complex matrices at concentrations as low as parts per billion. The results indicate that using a hydrocarbon PA during emulsion polymerization produces numerous polyfluorinated residuals. These must be identified and monitored to develop effective abatement strategies, ensuring responsible fluoropolymer manufacturing.

Emerging investigator series: nontargeted screening of aryl hydrocarbon receptor agonists in endangered beluga whales from the St. Lawrence Estuary: beyond legacy contaminants

The elevated concentrations of organohalogen contaminants in the endangered St. Lawrence Estuary (SLE) belugas have prompted the hypothesis that aryl hydrocarbon receptor (AhR) activity may be a contributor towards their potential adverse effects. While indirect associations between AhR and contaminant levels have been reported in SLE beluga tissues, AhR activity was never directly measured. Using bioassays and nontargeted analysis, this study contrasted AhR activity and agonist profiles between pooled tissue extracts of endangered SLE and non-threatened Arctic belugas. Tissue extracts of SLE belugas exhibited significantly higher overall AhR activity than that of Arctic belugas, with a 2000s SLE beluga liver extract exerting significantly higher activity than blubber extracts of SLE and Arctic belugas from the same time period. Contrary to our expectations, well-known AhR agonists detected by nontargeted analysis, including polychlorinated biphenyls (PCBs), were only minor contributors to the observed AhR activity. Instead, Tox21 suspect screening identified more polar chemicals, such as dyes and natural indoles, as potential contributors. Notably, the natural product bromoindole was selectively detected in SLE beluga liver at high abundance and was further confirmed as an AhR agonist. These findings highlighted the significance of the AhR-mediated toxicity pathway in belugas and underscored the importance of novel AhR agonists, particularly polar compounds, in its induction.

Spatial distribution, trophic magnification, and risk assessment of per- and polyfluoroalkyl substances in Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis): Risks of emerging alternatives

The Yangtze finless porpoise (YFP, Neophocaena asiaeorientalis asiaeorientalis) is the only freshwater cetacean found in China. However, per- and polyfluoroalkyl substances (PFASs) risks in YFPs remain unclear. In this study, legacy PFASs, their precursors and alternatives, were determined in YFP muscles (n = 32), liver (n = 29), kidney (n = 24), skin (n = 5), and blubbers (n = 25) collected from Poyang Lake (PL) and Yangtze River (YR) between 2017 and 2023. Perfluorooctane sulfonic acid (PFOS) was the predominant PFAS in all YFP tissues, with a median hepatic concentration of 1700 ng/g wet weight, which is higher than that in other finless porpoises worldwide. PFOS, chlorinated polyfluorinated ether sulfonates (Cl-PFESAs), and perfluoroalkane sulfonamides concentrations in YFP livers from PL were significantly higher than those from YR (p < 0.05); however, the opposite was observed for hexafluoropropylene oxide acids. Biomagnification and trophic magnification factors (BMF and TMF, respectively) of most PFASs in the YFP food web were > 1. Perfluoroheptane sulfonic acid had the highest BMF value (99), followed by 6:2 Cl-PFESA (94) and PFOS (81). The TMFmuscle and TMFliver values of the total PFASs were 3.4 and 6.6, respectively, and were significantly positively correlated with the fluorinated carbon chain length (p < 0.01). In addition, up to 62 % of the hazard quotients for 6:2 Cl-PFESA were > 1, which was higher than that of PFOS (48 %), suggesting a high hepatotoxicity of 6:2 Cl-PFESA to YFPs. Bioaccumulation and biotoxicity of legacy and emerging alternatives in aquatic organisms continue to be a concern, especially for underscoring the vulnerability of the long-lived and endangered species.

Relationship between nutritional condition and causes of death in beluga whales Delphinapterus leucas from the St. Lawrence estuary, Quebec, Canada

Carcasses of endangered beluga whales Delphinapterus leucas from the St. Lawrence Estuary, Canada, have been examined consistently since 1983 to determine causes of death. The objective of this study is to compare the nutritional condition of belugas that died of different causes. Previously published categories of death were refined to discriminate acute from chronic pathological processes. Bayesian linear models were used to predict cause of death from the scaled mass index (SMI). Causes of death were as follows: 'bacterial diseases', 'verminous pneumonia', 'toxoplasmosis', 'other parasitic diseases', 'other infectious diseases', 'trauma-entrapment', 'other noninfectious diseases', 'dystocia-postpartum complications', 'neonatal mortality', 'cancer', 'primary starvation' and 'undetermined'. The models predicted a lower nutritional condition for the 'neonatal mortality' in belugas <290 cm in length and for 'primary starvation' and 'verminous pneumonia' categories for belugas ≥290 cm. Belugas that died from 'dystocia-postpartum complications' or from 'undetermined causes' had a higher-than-average SMI. Animals in the 'trauma-entrapment' category did not exhibit the highest nutritional condition, which was unexpected since individuals that died from trauma or entrapment are often used as references for optimal nutritional condition in other cetacean populations. Females that died from dystocia and postpartum complications were in similar nutritional condition as females dead from other causes during, or shortly after, pregnancy. This suggests that these females are not obese, ruling out a possible cause of dystocia. Although studying dead animals biases results toward low nutritional condition, our findings support the link between chronic pathological processes and poorer nutritional condition in belugas.

Unique hepatic maternal transfer pattern of trace metals and perfluoroalkyl substances (PFAS) in a bluntnose sixgill shark (Hexanchus griseus)

The fate and distribution of environmental contaminants includes bioaccumulation within marine organisms. A deceased 4-m long adult female bluntnose sixgill shark, pregnant with 72 pups, was recovered from Coles Bay on Vancouver Island, BC, Canada in 2019. This specimen provided a unique opportunity to examine maternal transfer of contaminants in a yolk-sac viviparous shark species. Liver subsamples of the adult and offspring were analyzed for 18 targeted inorganic elements by inductively coupled plasma optical emission spectroscopy (ICP-OES) and 21 targeted perfluoroalkyl substances (PFAS) by liquid chromatography-electrospray ionization-high resolution mass spectrometry (LC-ESI-Orbitrap MS). The maternal-offspring transfer efficiencies in liver tissue were subsequently examined for both contaminant classes. Concentrations of all detectable metals apart from calcium and magnesium were found to be higher in the mother compared to the offspring, including substantial levels of toxic cadmium (6 ± 2 mg kg-1 dw) and lead (7 ± 3 mg kg-1 dw). Conversely, high maternal transfer efficiencies were observed for PFAS (i.e., ΣPFAS = 71 ± 9 ng g-1 ww in offspring compared to 13 ± 9 ng g-1 ww in the mother). This study highlighted the unique maternal transfer characteristics of PFAS in bluntnose sixgill sharks depending on the structure of the polar head group, with greater liver-to-liver transfer efficiencies observed for perfluorocarboxylic acids (PFCAs) than perfluorosulfonic acids (PFSAs) of the same fluorocarbon chain length.

Per/Polyfluoroalkyl Substances (PFASs) in a Marine Apex Predator (White Shark, Carcharodon carcharias) in the Northwest Atlantic Ocean

Per/polyfluoroalkyl substances (PFASs) are ubiquitous, highly persistent anthropogenic chemicals that bioaccumulate and biomagnify in aquatic food webs and are associated with adverse health effects, including liver and kidney diseases, cancers, and immunosuppression. We investigated the accumulation of PFASs in a marine apex predator, the white shark (Carcharodon carcharias). Muscle (N = 12) and blood plasma (N = 27) samples were collected from 27 sharks during 2018-2021 OCEARCH expeditions along the eastern coast of North America from Nova Scotia to Florida. Samples were analyzed for 47 (plasma) and 43 (muscle) targeted PFASs and screened for >2600 known and novel PFASs using liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS). Perfluoroalkyl carboxylates with carbon chain-length C11 to C14 were frequently detected above the method reporting limits in plasma samples, along with perfluorooctanesulfonate and perfluorodecanesulfonate. Perfluoropentadecanoate was also detected in 100% of plasma samples and concentrations were estimated semiquantitatively as no analytical standard was available. Total concentrations of frequently detected PFASs in plasma ranged from 0.56 to 2.9 ng mL-1 (median of 1.4 ng mL-1). In muscle tissue, nine targeted PFASs were frequently detected, with total concentration ranging from 0.20 to 0.84 ng g-1 ww. For all frequently detected PFASs, concentrations were greater in plasma than in muscle collected from the same organism. In both matrices, perfluorotridecanoic acid was the most abundant PFAS, consistent with several other studies. PFASs with similar chain-lengths correlated significantly among the plasma samples, suggesting similar sources. Total concentrations of PFASs in plasma were significantly greater in sharks sampled off of Nova Scotia than all sharks from other locations, potentially due to differences in diet. HRMS suspect screening tentatively identified 13 additional PFASs in plasma, though identification confidence was low, as no MS/MS fragmentation was collected due to low intensities. The widespread detection of long-chain PFASs in plasma and muscle of white sharks highlights the prevalence and potential biomagnification of these compounds in marine apex predators.

Spatial distribution, compositional characteristics, and source apportionment of legacy and novel per- and polyfluoroalkyl substances in farmland soil: A nationwide study in mainland China

China, as one of the largest global producers and consumers of per- and poly-fluoroalkyl substances (PFASs), faces concerning levels of PFAS pollution in soil. However, knowledge of their occurrence in agricultural soils of China on the national scale remains unknown. Herein, the first nationwide survey was done by collecting 352 soil samples from 31 provinces in mainland China. The results indicated that the Σ24PFASs concentrations were 74.3 - 24880.0 pg/g, with mean concentrations of PFASs in decreasing order of legacy PFASs > emerging PFASs > PFAS precursors (640.2 pg/g, 340.7 pg/g, and 154.9 pg/g, respectively). The concentrations in coastal eastern China were distinctly higher than those in inland regions. Tianjin was the most severely PFASs-contaminated province because of rapid urban industrialization. This study further compared the PFAS content in monoculture and multiple cropping farmland soils, finding the concentrations of PFASs were high in soils planted with vegetable and fruit monocultures. Moreover, a positive matrix factorization (PMF) model was employed to identify different sources of PFASs. Fluoropolymer industries and aqueous film-forming foams were the primary contributors. The contributions from different emission sources varied across the seven geographical regions. This study provides new baseline data for prevention and control policies for reducing pollution.

Bioaccumulation of Perfluoroalkyl Sulfonamides (FASA)

Hundreds of sites across the United States have high concentrations of perfluoroalkyl sulfonamides (FASA), but little is known about their propensity to accumulate in fish. FASA are precursors to terminal per- and polyfluoroalkyl substances (PFAS) that are abundant in diverse consumer products and aqueous film-forming foams manufactured using electrochemical fluorination (ECF AFFF). In this study, FASA with C3-C8 carbon chain lengths were detected in all fish samples from surface waters up to 8 km downstream of source zones with ECF AFFF contamination. Short-chain FASA ≤ C6 have rarely been included in routine screening for PFAS, but availability of new standards makes such analyses more feasible. Bioaccumulation factors (BAF) for FASA were between 1 and 3 orders of magnitude greater than their terminal perfluoroalkyl sulfonates. Across fish species, BAF for FASA were greater than for perfluorooctanesulfonate (PFOS), which is presently the focus of national advisory programs. Similar concentrations of the C6 FASA (<0.36-175 ng g-1) and PFOS (0.65-222 ng g-1) were detected in all fish species. No safety thresholds have been established for FASA. However, high concentrations in fish next to contaminated sites and preliminary findings on toxicity suggest an urgent need for consideration by fish advisory programs.

Variations in thyroid hormone levels in endangered St. Lawrence Estuary belugas: Potential linkage with stress and organohalogen contaminant exposure

The St. Lawrence Estuary (SLE) beluga (Delphinapterus leucas) population is highly exposed to an array of contaminants that were identified as one of the causes to the non-recovery of this endangered and declining population. In the last decade, an increasing number of parturition-associated complications and calf mortality has been reported in this population. It was suggested that elevated exposure to organohalogens (e.g., the halogenated flame retardants polybrominated diphenyl ethers [PBDEs]) and stress could play a role in this phenomenon by perturbing thyroid hormones. The objective of this study was to investigate the impact of concentrations of organohalogen contaminants and stress (cortisol levels) on thyroid hormone variations in adult male and female SLE belugas. Because plasma could not be collected in SLE belugas for ethical reasons, skin biopsy (n = 40) was used as a less-invasive alternative matrix to determine organohalogens (PBDEs and other halogenated flame retardants, polychlorinated biphenyls, and organochlorine pesticides), cortisol, and thyroid hormones (triiodothyronine [T3] and thyroxine [T4]), and their metabolites reverse T3 and 3,5-diiodothyronine [3,5-T2]). Cortisol and thyroid hormones were analyzed by ultra-performance liquid chromatography-multiple reactions monitoring mass spectrometry (UPLC-MRM/MS). This method was compared using skin and plasma samples obtained from Arctic belugas. Comparisons of linear models showed that cortisol was a weak predictor for T4, rT3 and 3,5-T2. Specifically, there was a weak significant negative association between T4 and cortisol levels. Moreover, in male SLE belugas, a weak significant positive association was found between T3 and Σ34PBDE concentrations in skin. Our findings suggest that stress (i.e., elevated skin cortisol levels) along with organohalogen exposure (mainly PBDEs) may be associated with thyroid hormone level perturbations in skin of cetaceans.

Suspect, Nontarget Screening, and Toxicity Prediction of Per- and Polyfluoroalkyl Substances in the Landfill Leachate

Landfills are the final stage of urban wastes containing perfluoroalkyl and polyfluoroalkyl substances (PFASs). PFASs in the landfill leachate may contaminate the surrounding groundwater. As major environmental pollutants, emerging PFASs have raised global concern. Besides the widely reported legacy PFASs, the distribution and potential toxic effects of numerous emerging PFASs remain unclear, and unknown PFASs still need discovery and characterization. This study proposed a comprehensive method for PFAS screening in leachate samples using suspect and nontarget analysis. A total of 48 PFASs from 10 classes were identified; nine novel PFASs including eight chloroperfluoropolyether carboxylates (Cl-PFPECAs) and bistriflimide (HNTf2) were reported for the first time in the leachate, where Cl-PFPECA-3,1 and Cl-PFPECA-2,2 were first reported in environmental media. Optimized molecular docking models were established for prioritizing the PFASs with potential activity against peroxisome proliferator-activated receptor α and estrogen receptor α. Our results indicated that several emerging PFASs of N-methyl perfluoroalkyl sulfonamido acetic acids (N-MeFASAAs), n:3 fluorotelomer carboxylic acid (n:3 FTCA), and n:2 fluorotelomer sulfonate (n:2 FTSA) have potential health risks that cannot be ignored.

Simulating behavior of perfluorooctane sulfonate (PFOS) in the mainstream of a river system with sluice regulations

Perfluorooctane sulfonate (PFOS) is a persistent, anionic and ubiquitous contaminant that undergoes long-range transport within the environment. Its behavior has attracted wide-range academic and regulatory attention. In this article, a mass balance model was employed to simulate PFOS concentrations in the mainstream of Haihe River water system, encompassing sluices and artificial rivers. The dynamic simulation of PFOS concentrations in both sediment and freshwater took into account fluctuations in PFOS emissions, water levels and water discharge. Furthermore, the study delved into exploring the impacts of sluices and artificial rivers on the behavior of PFOS. The simulated concentrations of PFOS in steady state agreed with the measured concentrations in surveys carried out in Nov. 2019, July 2020, Oct. 2020, and June 2021. Every year, approximately 24 kg PFOS was discharged into the Bohai Sea with Chaobai New River being the largest contributor for 44 %. Moreover, the transport of PFOS in the original rivers is likely to be restricted by sluices and replaced by artificial rivers. Monte Carlo analysis showed that model predictions of PFOS concentrations in sediment were subject to greater uncertainty than those in freshwater as the former is impacted by more parameters, such as density of sediment. This study provides a scientific basis for the local government to manage and control PFOS.

Closing the Organofluorine Mass Balance in Marine Mammals Using Suspect Screening and Machine Learning-Based Quantification

High-resolution mass spectrometry (HRMS)-based suspect and nontarget screening has identified a growing number of novel per- and polyfluoroalkyl substances (PFASs) in the environment. However, without analytical standards, the fraction of overall PFAS exposure accounted for by these suspects remains ambiguous. Fortunately, recent developments in ionization efficiency (IE) prediction using machine learning offer the possibility to quantify suspects lacking analytical standards. In the present work, a gradient boosted tree-based model for predicting log IE in negative mode was trained and then validated using 33 PFAS standards. The root-mean-square errors were 0.79 (for the entire test set) and 0.29 (for the 7 PFASs in the test set) log IE units. Thereafter, the model was applied to samples of liver from pilot whales (n = 5; East Greenland) and white beaked dolphins (n = 5, West Greenland; n = 3, Sweden) which contained a significant fraction (up to 70%) of unidentified organofluorine and 35 unquantified suspect PFASs (confidence level 2-4). IE-based quantification reduced the fraction of unidentified extractable organofluorine to 0-27%, demonstrating the utility of the method for closing the fluorine mass balance in the absence of analytical standards.

Class-specific recognition and monitoring of environmental steroid estrogens in real water systems utilizing aptamer base substitution mutagenesis approach

The same class of environmental steroid estrogens (SEs) with the highest estrogenic activity share the same chemical core structure and are often found together in the environment, posing significant risks to organismal health and environmental safety due to toxicity accumulation. In this study, a novel method for constructing the group-targeting aptasensor was developed to comprehensively analyze SEs. Through artificial intervention base substitution mutagenesis of adjacent bases T13 and C20 of the aptamer-binding domain recognizing 17β-estradiol, combined with docking calculations, the group-targeting SEs-aptamer for class-specific recognition SEs, such as estrone, estradiol, estriol, and ethinylestradiol were obtained. The binding constant of the SEs-aptamer to the SEs was 108 M-1. The established group-targeting SEs aptasensor exhibited high sensitivity within a concentration range from 0.1 to 10 nM and demonstrated strong interference resistance, as well as high stability and wide pH water applicability. It was further applied to analyze real water samples and monitor changes in SEs concentrations during the removal process by Chlorella pyrenoidosa. These successful applications have demonstrated the excellent ability of this aptasensor to monitor SE in the environment. The method offered a new approach and idea for recognizing and detecting the same class of environmental pollutants in complex systems.

Hepatic concentrations of per- and polyfluoroalkyl substances (PFAS) in dolphins from south-east Australia: Highest reported globally

Per- and polyfluoroalkyl substances (PFAS) concentrations were investigated in hepatic tissue of four dolphin species stranded along the south-east coast of Australia between 2006 and 2021; Burrunan dolphin (Tursiops australis), common bottlenose dolphin (Tursiops truncatus), Indo-Pacific bottlenose dolphin (Tursiops aduncus), and short-beaked common dolphin (Delphinus delphis). Two Burrunan dolphin populations represented in the dataset have the highest reported global population concentrations of ∑25PFAS (Port Phillip Bay median 9750 ng/g ww, n = 3, and Gippsland Lakes median 3560 ng/g ww, n = 8), which were 50-100 times higher than the other species reported here; common bottlenose dolphin (50 ng/g ww, n = 9), Indo-Pacific bottlenose dolphin (80 ng/g ww, n = 1), and short-beaked common dolphin (61 ng/g ww, n = 12). Also included in the results is the highest reported individual ∑25PFAS (19,500 ng/g ww) and PFOS (18,700 ng/g ww) concentrations, at almost 30 % higher than any other Cetacea reported globally. Perfluorooctane sulfonate (PFOS) was above method reporting limits for all samples (range; 5.3-18,700 ng/g ww), and constituted the highest contribution to overall ∑PFAS burdens with between 47 % and 99 % of the profile across the dataset. The concentrations of PFOS exceed published tentative critical concentrations (677-775 ng/g) in 42 % of all dolphins and 90 % of the critically endangered Burrunan dolphin. This research reports for the first time novel and emerging PFASs such as 6:2 Cl-PFESA, PFMPA, PFEECH and FBSA in marine mammals of the southern hemisphere, with high detection rates across the dataset. It is the first study to show the occurrence of PFAS in the tissues of multiple species of Cetacea from the Australasian region, demonstrating high global concentrations for inshore dolphins. Finally, it provides key baseline knowledge to the potential exposure and bioaccumulation of PFAS compounds within the coastal environment of south-east Australia.

Application of Nontarget High-Resolution Mass Spectrometry Fingerprints for Qualitative and Quantitative Source Apportionment: A Real Case Study

High-resolution mass spectrometry (HRMS) provides extensive chemical data, facilitating the differentiation and quantification of contaminants of emerging concerns (CECs) in aquatic environments. This study utilizes liquid chromatography-HRMS for source apportionment in Chebei Stream, an urban water stream in Guangzhou, South China. Initially, 254 features were identified as potential CECs by the nontarget screening (NTS) method. We then established 1689, 1317, and 15,759 source-specific HRMS fingerprints for three distinct sources, the mainstream (C3), the tributary (T2), and the rain runoff (R1), qualitatively assessing the contribution from each source downstream. Subsequently, 32, 55, and 3142 quantitative fingerprints were isolated for sites C3, T2, and R1, respectively, employing dilution curve screening for source attribution. The final contribution estimates downstream from sites C3, T2, and R1 span 32-96, 12-23, and 8-23%, respectively. Cumulative contributions from these sources accurately mirrored actual conditions, fluctuating between 103 and 114% across C6 to C8 sites. Yet, with further tributary integration, the overall source contribution dipped to 52%. The findings from this research present a pioneering instance of applying HRMS fingerprints for qualitative and quantitative source tracking in real-world scenarios, which empowers the development of more effective strategies for environmental protection.

Screening of Indoor Transformation Products of Organophosphates and Organophosphites with an in Silico Spectral Database

Numerous transformation products are formed indoors, but they are outside the scope of current chemical databases. In this study, an in silico spectral database was established to screen previously unknown indoor transformation products of organophosphorus compounds (OPCs). An R package was developed that incorporated four indoor reactions to predict the transformation products of 712 seed OPCs. By further predicting MS2 fragments, an in silico spectral database was established consisting of 3509 OPCs and 28,812 MS2 fragments. With this database, 40 OPCs were tentatively detected in 23 indoor dust samples. This is the greatest number of OPCs reported to date indoors, among which two novel phosphonates were validated using standards. Twenty-four of the detected OPCs were predicted transformation products in which oxidation from organophosphites plays a major role. To confirm this, the in silico spectral database was expanded to include organophosphites for suspect screening in five types of preproduction plastics. A broad spectrum of 14 organophosphites was detected, with a particularly high abundance in polyvinyl chloride plastics and indoor end-user goods. This demonstrated the significant contribution of organophosphites to indoor organophosphates via oxidation, highlighting the strength of in silico spectral databases for the screening of unknown indoor transformation products.

Identifying priority PBT-like compounds from emerging PFAS by nontargeted analysis and machine learning models

As traditional per and polyfluoroalkyl substances (PFAS) are phased out, emerging PFAS are being developed and widely used. However, little is known about their properties, including persistence, bioaccumulation, and toxicity (PBT). Screening for emerging PFAS relies on available chemical inventory databases. Here, we compiled a database of emerging PFAS obtained from nontargeted analysis and assessed their PBT properties using machine learning models, including qualitative graph attention networks, Insubria PBT Index and quantitative EAS-E Suite, VEGA, and ProTox-II platforms. Totally 282 homologues (21.8% of emerging PFAS) were identified as PBT based on the combined qualitative and quantitative prediction, in which 140 homologues were detected in industrial and nonbiological/biological samples, belong to four categories, i.e. modifications of perfluoroalkyl carboxylic acids, perfluoroalkane sulfonamido substances, fluorotelomers and modifications of perfluoroalkyl sulfonic acids. Approximately 10.1% of prioritized emerging PFAS were matched to chemical vendors and 19.6% to patents. Aqueous film-forming foams and fluorochemical factories are the predominant sources for prioritized emerging PFAS. The database and screening results can update the assessment related to legislative bodies such as the US Toxic Substances Control Act and the Stockholm Convention. The combined qualitative and quantitative machine learning models can provide a methodological tool for prioritizing other emerging organic contaminants.

Discussion. Has the human population become a sentinel for the adverse effects of PFAS contamination on wildlife health and endangered species?

Global contamination with per- and polyfluoroalkyl substances (PFAS) poses a threat to both human health and the environment, with significant implications for ecological conservation policies. A growing list of peer-reviewed publications indicates that PFAS can harm wildlife health and that the adverse effects associated with PFAS exposure in wildlife are in concordance with human epidemiological studies. The correlation of cross-species data supports a unique perspective that humans can be regarded as a sentinel for PFAS effects in other species. The health harms due to PFAS are potentially most concerning for populations of endangered and threatened species that are simultaneously exposed to PFAS and other toxic pollutants, and also face threats to their survival due to habitat loss, degradation of ecosystems, and over-harvesting. Human epidemiological studies on the PFAS doses associated with health harm present a rich source of information about potential impacts on wildlife health due to PFAS. Our analysis suggests that national and international efforts to restrict the discharges of PFAS into the environment and to clean up PFAS-contaminated sites present an opportunity to protect wildlife from chemical pollution and to advance species conservation worldwide.

Nontarget Analysis and Comprehensive Characterization of Iodinated Polyfluoroalkyl Acids in Wastewater and River Water by LC-HRMS with Cascade Precursor-Ion Exclusions and Algorithmic Approach

Poly- and perfluoroalkyl acids (PFAAs) are a large family of widespread contaminants of worldwide concern and well-known as "forever chemicals". Direct emission of PFAAs from the fluorochemical industry is a crucial source of PFAA pollutants in the environment. This study implemented nontarget analysis and comprehensive characterization for a category of new PFAA contaminants, i.e., iodinated PFAAs (IPFAAs), in fluorochemical industry wastewater and relevant contaminated river water by liquid chromatography-high-resolution mass spectrometry with a cascade precursor ion exclusion (PIE) strategy and in-house developed data extraction and processing algorithms. A total of 26 IPFAAs (including 2 isomers of an IPFAA) were found and identified with tentative molecular structures. Semiquantification of the IPFAAs was implemented, and the total concentrations of IPFAAs were 0.16-285.52 and 0.15-0.17 μg/L in wastewater and river water, respectively. The high concentrations in association with the predicted ecotoxicities and environmental behaviors demonstrate that these IPFAAs are worthy of more concern and further in-depth research. The cascade PIE strategy along with the data extraction and processing algorithms can be extended to nontarget analysis for other pollutants beyond IPFAAs. The nontarget identification and characterization outcomes provide new understanding on the environmental occurrence and pollution status of IPFAAs from a comprehensive perspective.

Per- and polyfluoroalkyl substances (PFAS) in white-tailed sea eagle eggs from Sweden: temporal trends (1969-2021), spatial variations, fluorine mass balance, and suspect screening

Temporal and spatial trends of 15 per- and polyfluoroalkyl substances (PFAS) were determined in white-tailed sea eagle (WTSE) eggs (Haliaeetus albicilla) from two inland and two coastal regions of Sweden between 1969 and 2021. PFAS concentrations generally increased from ∼1969 to ∼1990s-2010 (depending on target and site) and thereafter plateaued or declined, with perfluorooctane sulfonamide (FOSA) and perfluorooctane sulfonate (PFOS) declining faster than most perfluoroalkyl carboxylic acids (PFCAs). The net result was a shift in the PFAS profile from PFOS-dominant in 1969-2010 to an increased prevalence of PFCAs over the last decade. Further, during the entire period higher PFAS concentrations were generally observed in coastal populations, possibly due to differences in diet and/or proximity to more densely populated areas. Fluorine mass balance determination in pooled samples from three of the regions (2019-2021) indicated that target PFAS accounted for the vast majority (i.e. 81-100%) of extractable organic fluorine (EOF). Nevertheless, high resolution mass-spectrometry-based suspect screening identified 55 suspects (31 at a confidence level [CL] of 1-3 and 24 at a CL of 4-5), of which 43 were substances not included in the targeted analysis. Semi-quantification of CL ≤ 2 suspects increased the identified EOF to >90% in coastal samples. In addition to showing the impact of PFAS regulation and phase-out initiatives, this study demonstrates that most extractable organofluorine in WTSE eggs is made up of known (legacy) PFAS, albeit with low levels of novel substances.

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

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

Analytical approaches for screening of per- and poly fluoroalkyl substances in food items: A review of recent advances and improvements

Per and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals characterized by their ubiquitous nature in all environmental compartments which makes them of increasing concern due to their persistence, bioaccumulation, and toxicity (PBT). Several instrumental methodologies and separation techniques have been identified in the literature for the detection and quantification of PFAS in environmental samples. In this review, we have identified and compared common separation techniques adopted for the extraction of PFAS in food items, and analytical methodologies for identification and quantification of PFAS in food items of plant and animal origin, highlighting recent advances in tandem techniques for the high selectivity and separation of PFAS related compounds as well as knowledge gaps and research needs on current analytical methodologies.

Centurial Persistence of Forever Chemicals at Military Fire Training Sites

Drinking water contamination by per- and polyfluoroalkyl substances (PFAS) is widespread near more than 300 United States (U.S.) military bases that used aqueous film-forming foams (AFFF) for fire training and firefighting activities. Much of the PFAS at these sites consist of precursors that can transform into terminal compounds of known health concern but are omitted from standard analytical methods. Here, we estimate the expected duration and contribution of precursor biotransformation to groundwater PFAS contamination at an AFFF-contaminated military base on Cape Cod, Massachusetts, United States, by optimizing a geochemical box model using measured PFAS concentrations from a multidecadal time series of groundwater and a soil survey in the source zone. A toolbox of analytical techniques used to reconstruct the mass budget of PFAS showed that precursors accounted for 46 ± 8% of the extractable organofluorine (a proxy for total PFAS) across years. Terminal PFAS still exceed regulatory limits by 2000-fold decades after AFFF use ceased. Measurements and numerical modeling show that sulfonamido precursors are retained in the vadose zone and their slow biotransformation into perfluoroalkyl sulfonates (half-life > 66 yr) sustains groundwater concentrations of perfluorobutane sulfonate (PFBS) and perfluorohexane sulfonate (PFHxS). The estimated PFAS reservoir in the vadose zone and modeled flux into groundwater suggest PFAS contamination above regulatory guidelines will persist for centuries without remediation.

Integration of target, suspect, and nontarget screening with risk modeling for per- and polyfluoroalkyl substances prioritization in surface waters

Though thousands of per- and polyfluoroalkyl substances (PFAS) have been on the global market, most research focused on only a small fraction, potentially resulting in underestimated environmental risks. Here, we used complementary target, suspect, and nontarget screening for quantifying and identifying the target and nontarget PFAS, respectively, and developed a risk model considering their specific properties to prioritize the PFAS in surface waters. Thirty-three PFAS were identified in surface water in the Chaobai river, Beijing. The suspect and nontarget screening by Orbitrap displayed a sensitivity of > 77%, indicating its good performance in identifying the PFAS in samples. We used triple quadrupole (QqQ) under multiple-reaction monitoring for quantifying PFAS with authentic standards due to its potentially high sensitivity. To quantify the nontarget PFAS without authentic standards, we trained a random forest regression model which presented the differences up to only 2.7 times between measured and predicted response factors (RFs). The maximum/minimum RF in each PFAS class was as high as 1.2-10.0 in Orbitrap and 1.7-22.3 in QqQ. A risk-based prioritization approach was developed to rank the identified PFAS, and four PFAS (i.e., perfluorooctanoic acid, hydrogenated perfluorohexanoic acid, bistriflimide, 6:2 fluorotelomer carboxylic acid) were flagged with high priority (risk index > 0.1) for remediation and management. Our study highlighted the importance of a quantification strategy during environmental scrutiny of PFAS, especially for nontarget PFAS without standards.

Per- and Polyfluoroalkyl Substances in Canadian Fast Food Packaging

A suite of analytical techniques was used to obtain a comprehensive picture of per- and polyfluoroalkyl substances (PFAS) in selected Canadian food packaging used for fast foods (n = 42). Particle-induced gamma ray emission spectroscopy revealed that 55% of the samples contained <3580, 19% contained 3580-10 800, and 26% > 10 800 μg F/m2. The highest total F (1 010 000-1 300 000 μg F/m2) was measured in molded "compostable" bowls. Targeted analysis of 8 samples with high total F revealed 4-15 individual PFAS in each sample, with 6:2 fluorotelomer methacrylate (FTMAc) and 6:2 fluorotelomer alcohol (FTOH) typically dominating. Up to 34% of the total fluorine was released from samples after hydrolysis, indicating the presence of unknown precursors. Nontargeted analysis detected 22 PFAS from 6 different groups, including degradation products of FTOH. Results indicate the use of side-chain fluorinated polymers and suggest that these products can release short-chain compounds that ultimately can be transformed to compounds of toxicological concern. Analysis after 2 years of storage showed overall decreases in PFAS consistent with the loss of volatile compounds such as 6:2 FTMAc and FTOH. The use of PFAS in food packaging such as "compostable" bowls represents a regrettable substitution of single-use plastic food packaging.

First Discovery of Iodinated Polyfluoroalkyl Acids by Nontarget Mass-Spectrometric Analysis and Iodine-Specific Screening Algorithm

Per- and polyfluoroalkyl acids (PFAAs) including polyfluoroalkyl carboxylic acids and polyfluoroalkyl sulfonic acids are a large category of crucial environmental pollutants of global concern. Besides known PFAAs, numerous unknown species may exist in the environment, urgently needing discovery and characterization. This study implemented nontarget analysis for a group of novel PFAA pollutants, viz., iodinated PFAAs (I-PFAAs) in wastewater from a fluorochemical manufacturing park by liquid chromatography-high-resolution mass spectrometry in combination with an iodine-specific data-processing algorithm. The algorithm took into account the diagnostic fragment iodine ion (I-) together with carbon and sulfur isotopologue distributions. In total, 18 I-PFAA formulas involving 21 congeners were identified. Semiquantification was conducted, and the total concentrations of I-PFAAs were 1.9-274.7 μg/L, indicating severe pollution of I-PFAAs in the wastewater. The determined concentrations along with predicted environmental behaviors and toxicities demonstrate that I-PFAAs merit further in-depth investigation. The analytical method including the instrumental analysis and data-processing algorithm can be extended to screening and identification of I-PFAAs in other matrices. Furthermore, the analysis results for the first time provide recognition on the occurrence, distribution features, and pollution status of I-PFAAs in the environment.

Spatiotemporal and life history related trends of per- and polyfluoroalkyl substances in Indo-Pacific finless porpoises from south China sea (2007-2020)

Per- and polyfluoroalkyl substances (PFASs) levels in Indo-Pacific finless porpoises (Neophocaena phocaenoides) in the Pearl River Estuary (PRE), near the most economically developed region in China, have not been characterized. We measured the hepatic concentrations of twelve PFASs, including nine perfluoroalkyl carboxylic acids (PFCAs) and three perfluoroalkane sulfonic acids (PFSAs) in the finless porpoises (n = 21) collected from the PRE between 2007 and 2020. The average level of PFSAs was more than 2-times higher than that of PFCAs. The order of six dominant PFASs was perfluorooctane sulfonate (PFOS) > perfluoroundecanoic acid (PFUdA) > perfluorodecanoic acid (PFDA) > perfluorotridecanoic acid (PFTrDA) > perfluorononanoic acid (PFNA) > perfluorododecanoic acid (PFDoDA). The levels of Hepatic PFOS of 29% samples exceeded the no observable adverse effect level (NOAEL) values. The concentration of PFASs in males was significant higher than in females. PFASs levels were significantly negatively correlated with body length in males and positively correlated in females. PFASs levels in the PRE finless porpoises were lower than in humpback dolphins possibly due to different foraging habitat toward the coast and the consumption of less fish. PFCAs levels in finless porpoises from the western PRE were higher compared to Hong Kong, possibly due to the high-intensity sources of terrestrial anthropogenic pollutants. Significant increasing spatiotemporal trends of PFSAs, PFCAs and PFASs were found in finless porpoises from 2007 to 2020, suggesting a continuously increased risk of PFASs exposure for PRE cetaceans in the last decade.

Occurrence and Temporal Trends of Benzotriazole UV Stabilizers in Mollusks (2010-2018) from the Chinese Bohai Sea Revealed by Target, Suspect, and Nontarget Screening Analysis

Benzotriazole UV stabilizers (BZT-UVs), including 2-(3,5-di-tert-amyl-2-hydroxyphenyl)benzotriazole (UV-328) that is currently under consideration for listing under the Stockholm Convention, are applied in many commodities and industrial products. However, limited information is available on the interannual variation of their environmental occurrence. In this study, an all-in-one strategy combining target, suspect, and nontarget screening analysis was established to comprehensively explore the temporal trends of BZT-UVs in mollusks collected from the Chinese Bohai Sea between 2010 and 2018. Significant residue levels of the target analytes were determined with a maximum total concentration of 6.4 × 10³ ng/g dry weight. 2-(2-Hydroxy-3-tert-butyl-5-methyl-phenyl)-5-chloro-benzotriazole (UV-326), 5-chloro-2-(3,5-di-tert-butyl-2-hydroxyphenyl)benzotriazole (UV-327), and 2-(2-hydroxy-5-methylphenyl) benzotriazole (UV-P) were the predominant analogues, and UV-328 was the most frequently detected BZT-UV with a detection frequency (DF) of 87%. Whereas five biotransformation products and six impurity-like BZT-UVs were tentatively identified, their low DFs and semi-quantified concentrations suggest that the targeted analytes were the predominant BZT-UVs in the investigated area. A gradual decrease in the total concentrations of BZT-UVs was observed, accompanied by downward trends of the abundant compounds (e.g., UV-326 and UV-P). Consequently, the relative abundance of UV-327 increased because of its consistent environmental presence. These results suggest that continuous monitoring and risk assessment of BZT-UVs other than UV-328 are of importance in China.

Enhancing spectral quality in complex environmental matrices: Supporting suspect and non-target screening in zebra mussels with ion mobility

Identification of bioaccumulating contaminants of emerging concern (CECs) via suspect and non-target screening remains a challenging task. In this study, ion mobility separation with high-resolution mass spectrometry (IM-HRMS) was used to investigate the effects of drift time (DT) alignment on spectrum quality and peak annotation for screening of CECs in complex sample matrices using data independent acquisition (DIA). Data treatment approaches (Binary Sample Comparison) and prioritisation strategies (Halogen Match, co-occurrence of features in biota and the water phase) were explored in a case study on zebra mussel (Dreissena polymorpha) in Lake Mälaren, Sweden's largest drinking water reservoir. DT alignment evidently improved the fragment spectrum quality by increasing the similarity score to reference spectra from on average (±standard deviation) 0.33 ± 0.31 to 0.64 ± 0.30 points, thus positively influencing structure elucidation efforts. Thirty-two features were tentatively identified at confidence level 3 or higher using MetFrag coupled with the new PubChemLite database, which included predicted collision cross-section values from CCSbase. The implementation of predicted mobility data was found to support compound annotation. This study illustrates a quantitative assessment of the benefits of IM-HRMS on spectral quality, which will enhance the performance of future screening studies of CECs in complex environmental matrices.

Chronic toxicity of PFAS-free AFFF alternatives in terrestrial plant Brassica rapa

Fluorine (F)-free firefighting foams will be replacing per- and polyfluoroalkyl substances (PFAS)-containing aqueous film-forming foams (AFFFs) at U.S. military installations imminently, yet the environmental impacts of F-free foams are largely unknown. Ecotoxicity assessment of F-free foams is urgently needed to avoid replacement regret. In this study, we comparatively assessed phytotoxicity of six F-free formulations and one current short-chain fluorinated AFFF in terrestrial plant Brassica rapa. Five of six F-free formulations exerted higher toxicity than the short-chain AFFF to the growth and reproduction of B. rapa, with 8-51 times and > 10 times lower EC₅₀ values, respectively. Nontargeted analysis indicated the occurrence of transformation products of the test formulations in the above-ground plant tissues. In agreement with their phytotoxicity, the five highly toxic F-free formulations generated more transformation products with higher peak intensities in plant tissues than the two weakly toxic formulations. The most abundant transformation products detected in plant extracts were suspect transformation products derived from diethylene glycol monobutyl ether, a common ingredient of the five toxic formulations. This study provides ecotoxicological data that, combined with data from all related ongoing research, should be used in decision making regarding recommendations for manufacturing and use of candidate F-free foams.

Targeted and Suspect Screening of Per- and Polyfluoroalkyl Substances in Cosmetics and Personal Care Products

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic chemicals reported in cosmetics and personal care products as ingredients, possible impurities in the raw material manufacturing process, or degradation products. The purpose of this study was to further delineate contributions of these varying PFAS sources to these products. Thirty-eight cosmetics and personal care products were selected and analyzed for polyfluoroalkyl phosphates (PAPs), perfluoroalkyl carboxylic acids (PFCAs), fluorotelomer sulfonic acids (FTSAs), and perfluoroalkyl sulfonic acids (PFSAs) using targeted liquid chromatography tandem mass spectrometry (LC-MS/MS). A subset of products was also subjected to suspect screening using LC-high resolution mass spectrometry (HRMS) for >200 compounds. Results of LC-MS/MS and LC-HRMS indicated a predominant and ubiquitous presence of PAPs (detection frequency 99.7%, mean and median ΣPAPs 1 080 000 and 299 ng/g). Total median PFCA and PFSA concentrations were 3 and 38 times lower, respectively. There were significant correlations (Spearman's correlation coefficients = 0.60-0.81, p < 0.05) between 6:2 PAPs and their biotransformation products. Low levels of other PFAS classes were detected, including those previously measured in wastewater and human blood (e.g., hydrido-PFCAs), and five compounds associated with aqueous film-forming foams. Overall, these data highlight that cosmetics and personal care products can contain a breadth of PFAS at extremely high levels, leading to human and environmental exposure.

Occurrence and temporal trends of industrial antioxidants and UV absorbents in the endangered St. Lawrence Estuary beluga whale (Delphinapterus leucas)

Elevated contaminant exposure has been identified as a stressor that has negative impacts on the health and recovery of the endangered St. Lawrence Estuary (SLE) beluga (Delphinapterus leucas) population. However, the accumulation of many groups of contaminants of emerging concern is still unknown in the SLE beluga. The objective of this study was to investigate the occurrence and temporal trends (2000-2017) of synthetic phenolic antioxidants (SPAs), secondary aromatic amines (Ar-SAs), benzotriazole UV stabilizers (BZT-UVs), and organic UV filters (UVFs) in the blubber (n = 69) and liver (n = 80) of SLE beluga carcasses recovered in the SLE. The SPA 2,6-di-tert-butyl-1,4-benzoquinone (BHTQ) was the most prevalent contaminant in the blubber (detection frequency: 86 %; median: 71.1 ng/g wet weight (ww)) and liver (50 %; 12.2 ng/g ww) of SLE belugas. In the blubber, 2-hydroxy-4-methoxybenzophenone (BP3) (36 %; 3.15 ng/g ww) and 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethyl butyl)phenol (UV329) (49 %; 6.84 ng/g ww) were the most frequently detected UVFs and BZT-UVs, respectively. Ar-SAs were not detected in most of the blubber and liver samples. Blubber accumulated higher levels of BHTQ and UV329 than liver, whereas the levels of BP3 were greater in the liver. Male SLE beluga accumulated greater concentrations of UV329 in blubber compared to females. These results indicated that the accumulation of BHTQ, UV329 and BP3 in SLE belugas is tissue- and sex-specific. BHTQ showed a decreasing trend in the blubber (2000-2017) of male SLE beluga, whereas no significant trend of this contaminant was found in females. UV329 showed no discernible temporal trend. This study established a baseline for the future monitoring of SPAs, Ar-SAs, BZT-UVs and UVFs in belugas and other marine mammals.

Bioaccumulation and trophic magnification of emerging and legacy per- and polyfluoroalkyl substances (PFAS) in a St. Lawrence River food web

Research on per- and polyfluoroalkyl substances (PFAS) in freshwater ecosystems has focused primarily on legacy compounds and little is still known on the presence of emerging PFAS. Here, we investigated the occurrence of 60 anionic, zwitterionic, and cationic PFAS in a food web of the St. Lawrence River (Quebec, Canada) near a major metropolitan area. Water, sediments, aquatic vegetation, invertebrates, and 14 fish species were targeted for analysis. Levels of perfluorobutanoic acid (PFBA) in river water exceeded those of perfluorooctanoic acid (PFOA) or perfluorooctane sulfonate (PFOS), and a zwitterionic betaine was observed for the first time in the St. Lawrence River. The highest mean PFAS concentrations were observed for the benthopelagic top predator Smallmouth bass (Micropterus dolomieu, Σ₆₀PFAS ∼ 92 ± 34 ng/g wet weight whole-body) and the lowest for aquatic plants (0.52-2.3 ng/g). Up to 33 PFAS were detected in biotic samples, with frequent occurrences of emerging PFAS such as perfluorobutane sulfonamide (FBSA) and perfluoroethyl cyclohexane sulfonate (PFECHS), while targeted ether-PFAS all remained undetected. PFOS and long-chain perfluorocarboxylates (C10-C13 PFCAs) dominated the contamination profiles in biota except for insects where PFBA was predominant. Gammarids, molluscs, and insects also had frequent detections of PFOA and fluorotelomer sulfonates, an important distinction with fish and presumably due to different metabolism. Based on bioaccumulation factors >5000 and trophic magnification factors >1, long-chain (C10-C13) PFCAs, PFOS, perfluorodecane sulfonate, and perfluorooctane sulfonamide qualified as very bioaccumulative and biomagnifying. Newly monitored PFAS such as FBSA and PFECHS were biomagnified but moderately bioaccumulative, while PFOA was biodiluted.

Simplifying Nontargeted Analysis of PFAS in Complex Food Matrixes

Background

Per- and polyfluoroalkyl substances (PFAS) are a class of toxic environmental contaminants that are characterized by their high chemical stability and enormous structural diversity.

Objective

The limited availability of PFAS reference standards is the main motivation for developing nontargeted analytical methods. Current concepts are complex and rely on multiple filtering steps (e.g., assumption of homologous series, detection of mass defects, generic fragments, and spectra obtained from web-based sources).

Method

High-resolution mass spectrometry (HRMS)–based chromatograms of fish liver extracts were deconvoluted. Based on the ion abundance between the monoisotopic and the first isotopic peak, the number of carbons (C) was estimated for each extracted feature. A mass over carbon (m/C) and mass defect over carbon (md/C) ratio was calculated.

Results

PFAS-related peaks are strongly discriminated from matrix peaks when plotting m/C versus md/C. This enables nontarget detection of PFAS present at low µg/kg concentration in complex food matrixes.

Conclusions

The proposed concept is highly selective by revealing a relatively small number of high-probability PFAS candidates (features). The small number of surviving candidates permits the MS/MS-based confirmation of each feature. This strategy led to the finding of one PFAS not present in the reference standard solution, as well as the detection of an unexpected set of PFAS adducts.

Highlights

The proposed concept of mass over carbon versus mass defect over carbon is suited for the nontarget detection of low amounts of PFAS in complex matrixes. It should be capable of detecting any PFAS (F/H ratio should be &gt;1:1) regardless of the ionization mode.

Suspect screening and nontargeted analysis of per- and polyfluoroalkyl substances in representative fluorocarbon surfactants, aqueous film-forming foams, and impacted water in China

Massive usage of aqueous film-forming foams (AFFF) containing fluorocarbon surfactants (FS) is one of the major sources of per- and polyfluoroalkyl substances (PFAS) contamination, which poses negative environmental and health effects. However, there is a critical knowledge gap regarding PFAS chemical compositions in high consumption FS products which were used in AFFFs on the Chinese market and in water impacted by such products. This study firstly applied a comprehensive suspect screening and nontargeted analysis (NTA) workflow to investigate the main ionic and neutral PFAS in FS products from the largest Chinese vendor and compared with two international brands to unveil the PFAS used in AFFF. Overall, 24 classes of PFAS, including 69 compounds, were tentatively identified in FS products, and high concentrations of neutral PFAS were found in polymer-based products, indicating potential environmental risk. In addition, we applied a simplified data mining process to capture 36 PFAS from the impacted water, and the relationship among FS, AFFF concentrates and impacted water was explored. This study parsed the PFAS characteristics in AFFF-related industrial products and impacted water in China, which is instrumental for managing and controlling prioritized PFAS in this field.

A food web bioaccumulation model for the accumulation of per- and polyfluoroalkyl substances (PFAS) in fish: how important is renal elimination?

Per- and polyfluoroalkyl substances (PFAS) are a large class of highly fluorinated anthropogenic chemicals. Some PFAS bioaccumulate in aquatic food webs, thereby posing risks for seafood consumers. Existing models for persistent organic pollutants (POPs) perform poorly for ionizable PFAS. Here we adapt a well-established food web bioaccumulation model for neutral POPs to predict the bioaccumulation behavior of six perfluoroalkyl acids (PFAAs) and two perfluoroalkyl ether acids (HFPO-DA, 9-Cl-PF3ONS) produced as PFAA replacements. The new model includes sorption to blood plasma proteins and phospholipids, empirically parameterized membrane transport, and renal elimination for PFAAs. Improved performance relative to prior models without these updates is shown by comparing simulations to field and lab measurements. PFAS with eight or more perfluorinated carbons (η_pfc ≥ 8, i.e., C8 perfluorosulfonic acid, C10-C11 perfluorocarboxylic acid, 9-Cl-PF3ONS) are often the most abundant in aquatic food webs. The new model reproduces their observed bioaccumulation potential within a factor of two for >80% of fish species, indicating its readiness to support development of fish consumption advisories for these compounds. Results suggest bioaccumulation of η_pfc ≥ 8 PFAS is primarily driven by phospholipid partitioning, and that renal elimination is negligible for these compounds. However, specific protein binding mechanisms are important for reproducing the observed tissue concentrations of many shorter-chain PFAAs, including protein transporter-mediated renal elimination. Additional data on protein-binding and membrane transport mechanisms for PFAS are needed to better understand the biological behavior of shorter-chain PFAAs and their alternatives.