Distribution and effects of branched versus linear isomers of PFOA, PFOS, and PFHxS: A review of recent literature

Per- and polyfluoroalkyl substance profiles revealed by targeted and non-targeted screening in European starling eggs from sites across Canada

Per- and polyfluoroalkyl substances (PFAS) are environmental contaminants including in wildlife but are a fraction of the growing 1000s of PFAS that are being produced. Our study objective was to determine and compare PFAS profiles using targeted analysis and non-targeted analysis (NTA) methods in European starling (Sturnus vulgaris) eggs collected in April/May of 2023 from 11 nesting box sites across Canada at locations described as landfills, near parks, forest, urban, near wastewater facilities, rural, waste management facilities and urban industrial. NTA revealed 41 PFAS at variable detection frequencies in eggs samples and up to 29 PFAS were quantifiable by targeted method analysis. The Σ29PFAS mean concentration (range) (1048 (991-1078) ng/g ww) at the lone landfill site at Brantford were the highest whereas all other sites were <151 ng/g w.w. Σ29PFAS concentrations were not significantly different (p < 0.05) among the 10 non-Brantford landfill sites including the Nova Scotia hospital site (range of 58.0-152 ng/g ww). Two side-chain fluorinated polymer surfactants for a sub-set of egg pools, and 4 emerging PFAS including GenX (or HFPO-DA), F-53B components and ADONA for all pools were not detectable. Confirmed against in-house synthesized standards, 8:2 FTOH sulfate, was detected in 93 % of all samples, and 6:2, 10:2, and 12:2 FTOH sulfates were also detected only in Brantford landfill site eggs. FTOHs, which are likely precursors of FTOH sulfate metabolites, were not detectable in any samples. This suggested that FTOH sulfate metabolites may be suitable biomarkers of exposure to FTOHs and perhaps other PFAS. Among all nest box locations, other additional NTA detected PFAS in eggs were e.g. branched isomers of PFOA, PFHpS, PFNS and PFDS and 6:2 diPAP. Overall, more targeted PFAS candidates should be monitored in starling eggs.

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.

Occurrence and distribution of per- and polyfluoroalkyl substances (PFAS) in tidal salt marsh creeks

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous global contaminants where the ocean plays a critical role in global PFAS cycling. Large estuarine systems are conduits for anthropogenic contaminants, but little is known regarding PFAS in small tidal creek systems. Surface waters from seven tidal creeks were analyzed for 16 target PFAS including legacy and replacement PFAS. Mean total PFAS ranged from 139.4 to 12,293.8 ng/L in terrestrial influenced upland sampling sites and 33.9-176.3 ng/L in tidal creek mouth sites. Nine PFAS were negatively correlated with salinity and positively correlated with DOC (p < 0.05), indicating that the source of PFAS is predominantly terrestrial. Mean total PFAS of upland sites also had a strong positive relationship with percent impervious surface (R2 = 0.99), indicating the importance of human land use influencing PFAS occurrence. Results of this study will inform future investigations of tidal creeks and their role in PFAS dynamics at the land-sea interface.

Unveiling the Differential Intensity of Fluorous Active Sites Toward Selective Polyfluoroalkyl Substance Removal: Insights into Adsorption and Desorption Trade-Offs

The design of selective sorption sites for per- and polyfluoroalkyl substance (PFAS) removal, integrated with efficient regenerative strategies, remains a critical yet underexplored challenge. While existing technologies prioritize adsorption capacity over regenerative sustainability, we engineered a fluorinated hydrogel with tailored fluorous binding sites to target PFAS via their hydrophobic C-F termini. This design achieved over 90% PFAS removal efficiency in real water matrices (e.g., tap and lake water), at environmentally relevant concentrations (1 μg L-1), with robust resistance to competing background ions and natural organic matter. Selectivity correlated strongly with PFAS chain length (F9 > F12 > F6), driven by stable adsorption configurations (C-F···F-C vs C-H···F-C) and a favorable adsorption energy of -29.06 kcal mol-1. Leveraging controlled noncovalent F···F interactions, the hydrogel enabled efficient desorption (60-80% efficiency using 1% NaCl, 1% NH4Cl, or 0.5% NH4OH-NH4Cl) without structural degradation. Full regeneration (>92% recovery) was achieved with 50% methanol, supporting five reuse cycles with minimal performance decline. In continuous operation, using 1% NaCl achieved a 10-fold PFAS enrichment, while 50% methanol enabled a significantly higher 51-fold enrichment. Both approaches reduced eluent consumption by 20-50% compared to conventional activated carbon and resins. Overall, balancing PFAS adsorption and desorption trade-offs significantly reduces environmental footprint and operational costs, providing a sustainable strategy for PFAS remediation.

Isomers of perfluorooctanesulfonate exhibit preferential infiltration and contrasting ionic associations between surface water and groundwater

We evaluated the spatiotemporal variations of perfluorooctane sulfonate (PFOS) contamination in various environmental matrices of Yorkshire, United Kingdom. The dataset indicates decreasing PFOS concentrations between 2005 and 2023 in the groundwater of Yorkshire, UK. We used statistical methods, including kriging and hydrogeochemical plots, to analyze co-occurring ions, land use influences, and pollution sources. Groundwater exhibited less PFOS concentration, mainly in the form of linear (L) and branched (B) isomers, than surface water. PFOS (B) was more prevalent in groundwater and associated with F, Cr, Cu, Cl, and pH. PFOS pollution in the surface water exhibited source line ionic pairing with Hg, As, and dissolved carbon. Surface water clustering reveals the connection between branched and linear PFOS with Ca-Mg-Cu forms a larger cluster that interacts with major groups like SO4-Na-K and NO3, while the ionic PFOS cluster with As-Cl indicates strong source-level associations, especially in urban areas. Further, isomers were found to be evenly distributed in surface water, which alters during infiltration into groundwater. However, further research is required to provide confirmatory evidence of PFOS pathways linking with surface-groundwater interactions. This study likely represents the first comprehensive analysis of PFOS isomers that provides crucial emphasis on the need for monitoring emerging chemicals, such as PFOS, PFCs, and PFAAs, to establish timely and stringent regulatory guidelines.

Branched perfluorohexanesulfonic acid (PFHxS) and perfluoroheptanoic acid (PFHpA): 'Safer' per- and polyfluoroalkyl substances (PFASs) alternatives for their effects on gut microbiota and metabolic function in children

This study examined the effects of branched perfluorohexanesulfonic acid (PFHxS) and perfluoroheptanoic acid (PFHpA), two alternatives to per- and polyfluoroalkyl substances (PFASs), on gut microbiota and metabolic function in Chinese children aged 6-9 years. A total of 336 children were enrolled, providing plasma and fecal samples. Gut microbiota composition was assessed through 16S rRNA gene sequencing, and fecal metabolites and short-chain fatty acids (SCFAs) were analyzed using targeted metabolomics profiling and high-performance liquid chromatography (HPLC), respectively. PFASs in plasma samples were detected using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The results revealed that exposure to PFHpA significantly reduced microbial diversity and richness in the gut microbiota. Specific bacterial genera were found to be positively or negatively associated with branched PFHxS and PFHpA exposures (β = -0.008---0.009, P_fdr = <0.001---0.048), with Parabacteroides positively correlated with branched PFHxS and Lachnospiraceae FCS020 group negatively correlated with PFHpA. Metabolomic analysis showed that branched PFHxS and PFHpA exposures were associated with distinct changes in fecal metabolite profiles (β = -0.182---0.177, P_fdr = 0.015---0.172), particularly reducing fatty acids and amino acids. Additionally, higher exposure to PFHpA was linked to a reduction in SCFA profiles, such as valeric acid (β = -0.691 - -0.341, P = 0.011---0.030). This study offers new insights into the potential adverse effects of PFASs alternatives, specifically branched PFHxS and PFHpA, on the gut microbiome and metabolic health in children.

Serum biomonitoring of per- and polyfluoroalkyl substances (PFASs) in the adult population of Switzerland: Results from the pilot phase of the Swiss health study

Monitoring human exposure to per- and polyfluoroalkyl substances (PFASs) is of significant public health relevance, given the documented associations between PFAS exposure and a range of adverse health outcomes. This study aimed to provide a sensitive and reliable analytical approach for the determination of PFASs in human serum and to advance the understanding of PFAS exposure. Serum samples from 630 adult participants from the population-based Swiss Health Study pilot phase were analysed for 30 legacy and emerging PFASs. Quantitative analysis was performed after specific sample preparation using high-performance liquid chromatography coupled to mass spectrometry. The association between PFAS serum concentrations and selected demographic and behavioural parameters of interest was assessed using linear regression. The developed method enabled sensitive high-throughput analysis and resulted in reliable validation parameters and robust quantification performance. The study revealed that, while the prevalence of emerging PFASs was observed to be marginal, legacy PFASs predominated. Perfluorooctane sulfonic acid (PFOS, geometric mean (GM) 6.6 ng/mL), perfluorooctanoic acid (PFOA, GM 1.3 ng/mL) and perfluorohexane sulfonic acid (PFHxS, GM 1.2 ng/mL) were detected in all serum samples and contributed 88 % to the median sum of determined PFASs (10.3 ng/mL). The levels of PFOA and PFOS were found to be associated with age and gender. Furthermore, PFOS levels were associated with consumption of fish, particularly freshwater species, while PFOA levels were negatively associated with the duration of breastfeeding. Regional disparities were also observed. Several results exceeded specific health thresholds for PFAS intake or human biomonitoring, but the observed values were overall comparable to similar studies conducted worldwide. The provision of comprehensive information on a wide range of legacy and emerging PFASs facilitates a more complete identification of possible sources of exposure, not only in the regions concerned, but also beyond, and establishes a robust foundation for the guidance of future investigations.

Contamination of per- and poly-fluoroalkyl substances in agricultural soils: A review

Numerous reviews have focused on the chemistry, fate and transport, and remediation of per- and poly-fluoroalkyl substances (PFAS) across various environmental media. However, there remains a significant gap in the literature regarding a comprehensive review specifically addressing PFAS contamination within agricultural soils. Recognizing the threat PFAS pose to ecosystems and human health, this review critically examines the sources of PFAS in agricultural environments, their uptake and translocation within plant systems, and recent advancements in soil remediation techniques. PFAS ingress into agricultural soils primarily occurs through the application of biowastes, wastewater, and pesticides, necessitating a thorough examination of their pathways and impacts. Factors such as carbon chain length, salinity, temperature, and pH levels affect PFAS uptake and distribution within plants, ultimately influencing their transfer through the food web. Moreover, this review explores a range of physical, chemical, and biological strategies currently employed for the remediation of PFAS-contaminated agricultural soils.

Effects of Serum Insulin and Insulin-Like Growth Factor 1 Levels on the Association between Fetal Growth and Per- and Polyfluoroalkyl Substance Exposure Based on a Nested Case-Control Study

Insulin and insulin-like growth factor 1 (IGF1) play key roles in fetal growth and development. However, their roles in the association between fetal growth and perfluoroalkyl and polyfluoroalkyl substance (PFAS) exposure remain unclear. In this study, the levels of 34 PFAS, IGF1, and insulin were measured in 258 paired mother-infant serum samples collected from a nested case-control study in Maoming city. Isomeric perfluorooctanesulfonate (PFOS) exposure significantly increased the preterm birth or low birth weight (PTB/LBW) risk, and the odds ratios for ∑2m, 3+4+5m, iso, and branched PFOS were 1.50, 1.72, 1.61, and 1.77, respectively. Cord IGF1 could explain 15.4, 13.4, 9.7, and 11.9% of these associations, respectively. Additionally, cord IGF1 mediated 12.3 to 44.6% of the associations between PFOS isomers, perfluorooctanoate acid (PFOA), and its alternative (perfluorobutanoic acid: PFBA) with a fetal growth index. For instance, cord IGF1 contributed 42.0% (95% Cl: 0.8, 140.0%), 42.7% (95% Cl: 13.0, 110.0%), and 43.0% (95% Cl: 8.4, 130.0%) to the associations between z-scores of birth weight and branched PFOS, PFOA, and PFBA, respectively. These findings suggest that cord IGF1 plays a mediating role in the associations between PFAS exposure and fetal growth.

Isomer-specific sediment-water partitioning and bioaccumulation of perfluoroalkyl sulfonyl fluorides

Perfluoroalkyl sulfonyl fluorides (PFASFs) have long been used as crucial synthetic intermediates in the production of various perfluoroalkyl substances. While, knowledge on the environmental occurrence and behaviors of PFASFs in the aquatic environment is still very limited, especially at the isomer-specific level. In this study, surface water, sediment, and fish samples were collected from the water environment near a wastewater treatment plant outlet, and analyzed them for five PFASFs. The highest mean water concentration was observed for linear perfluorobutyl sulfonyl fluoride (l-PFBSF; 122 ng/L, 10-457 ng/L). While, linear perfluorooctane sulfonyl fluoride (l-PFOSF) displayed the highest mean concentration in collected sediment (108 ng/g dw, 78-271 ng/g dw) and fish (113 ng/g ww, 48-244 ng/g ww). For detected PFASFs, their branched isomers accounted for mean 16-29 %, 8.2-11 %, and 16-25 % of total PFASFs (sum of linear and branched isomers) in water, sediment, and fish samples, respectively. Calculated log-transformed sediment-water partitioning coefficients (log Koc) of linear PFASFs linearly increased with the increasing carbon chain length, with the mean values ranging from 2.1 ± 0.36 (l-PFBSF) to 3.9 ± 0.18 (l-PFOSF). Calculated log-transformed bioaccumulation factors (log BAF) of linear PFASFs increased from 1.7 ± 0.34 (l-PFBSF) to 3.0 ± 0.27 (l-PFOSF) with the carbon chain length. Branched isomers of detected PFASFs displayed lower log Koc and log BAF values than their respective linear isomers. To our knowledge, this study provides the first evidence on isomer-specific environmental behaviors of PFASFs, which is crucial for assessing the ecological risks these compounds may pose.

Occurrence, bioaccumulation and trophodynamics of per- and polyfluoroalkyl substances (PFAS) in terrestrial and marine ecosystems of Svalbard, Arctic

Per- and polyfluoroalkyl substances (PFAS) enter the Arctic through long-range transport and local pollution. To date, little is known about their behavior in plant and benthic marine food webs in remote Arctic. In this study, we analyzed the environmental distribution and nutrient transfer of 20 PFAS in soil, sediment, plant and benthic biota samples collected between 2014 and 2016 in Svalbard, Arctic. Total concentrations of PFAS were in the ranges of 0.12-4.84 ng/g dry weight (dw) in soil, 0.15-0.93 ng/g dw in sediment, 0.11-16.6 ng/g dw in plant, and 0.049-26.2 ng/g dw in marine biota. Perfluorocarboxylic acids (PFCAs) dominated Σ20PFAS in all sample types except amphipods, in which perfluorooctane sulfonate (PFOS) made up 80 % of Σ20PFAS. The profile of PFAS components observed in the terrestrial and marine ecosystems suggests that atmospheric transport and oxidation of volatile precursors are important sources of PFCAs in the Arctic region. However, the impact of long-distance ocean transport and local emissions cannot be ignored. The biota-sediment or biota-soil bioaccumulation factors (BSAF) differed among plants and biota species, with mountain avens (BSAF of Σ20PFAS: 12.1) and amphipods (BSAF of Σ20PFAS: 44.9) having higher accumulation potential. PFOS, perfluorohexane sulfonamide (FHxSA) and Σ20PFAS have biomagnification potential in Arctic benthic biota, but short-chain PFCA exhibits trophic dilution. This is one of few studies to investigate the environmental behavior of PFAS in terrestrial and aquatic ecosystems in the remote Arctic, providing a basis for investigating the ecological risks of PFAS in polar regions.

Spatial and vertical distribution of per- and polyfluoroalkyl substances (PFASs) in the water columns of the regional seas of South Korea

This study focused on analyzing the spatial and vertical distributions of 28 per- and polyfluoroalkyl substances (PFASs), which comprised five precursors and three alternatives, in the water columns of the regional seas surrounding South Korea, such as the Yellow Sea (YS, Y1-Y10), East China Sea (ECS, EC1-EC6), South Sea (SS, S1-S5), and East Sea (ES, E1-E7). The concentrations of these PFASs detected in 204 seawater samples varied from below the limit of detection ( Collapse

Key Words

• Chemical tracer
• East Sea
• HPLC-MS/MS
• Ocean current
• PFASs
• Yellow Sea

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MESH Headings

• Fluorocarbons/analysis
• Republic of Korea
• Water Pollutants, Chemical/analysis
• Environmental Monitoring
• Seawater/chemistry
• Oceans and Seas
• Caprylates/analysis

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Grants Collapse

Affiliation(s)

Sunmi Yang Department of Earth, Environmental & Space Sciences, Chungnam National University, Daejeon 34134, Republic of Korea
Jiyun Gwak Department of Earth, Environmental & Space Sciences, Chungnam National University, Daejeon 34134, Republic of Korea
Mungi Kim Department of Earth, Environmental & Space Sciences, Chungnam National University, Daejeon 34134, Republic of Korea
Jihyun Cha Department of Earth, Environmental & Space Sciences, Chungnam National University, Daejeon 34134, Republic of Korea
Youngnam Kim Department of Earth, Environmental & Space Sciences, Chungnam National University, Daejeon 34134, Republic of Korea
Yeonjung Lee Ocean Climate Response & Ecosystem Research Department, Korea Institute of Ocean Science and Technology, Busan 49111, Republic of Korea
Hyo-Bang Moon Department of Marine Science and Convergence Engineering, Hanyang University, Ansan 15588, Republic of Korea
Seongjin Hong Department of Earth, Environmental & Space Sciences, Chungnam National University, Daejeon 34134, Republic of Korea.

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Collaborators Collapse

Assessing PFAS in drinking water: Insights from the Czech Republic's risk-based monitoring approach

This study investigates the presence of perfluoroalkyl substances (PFAS) in the drinking water supplies in the Czech Republic using a risk-based monitoring approach. Tap water samples (n = 27) from sources close to areas potentially contaminated with PFAS were analysed. A total of 28 PFAS were measured using ultra-performance liquid chromatography with tandem mass spectrometry after solid phase extraction. Total PFAS concentrations (∑PFAS) varied from undetectable to 90.8 ng/L, with perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA) and perfluorobutane sulfonic acid (PFBS) being the most abundant, detected in over 70% of samples. Risk-based monitoring in drinking water showed that commercial wells had higher PFAS levels compared to tap water, particularly C4-C9 perfluorocarboxylic acids (PFCAs), possibly due to proximity to industrial areas. However, the hypothesis that risk-based monitoring is more effective than random monitoring was not confirmed, possibly because specific sources did not produce the target PFAS or because of the wide range and less obvious sources of potential contamination. The study also assessed exposure risks and compliance with regulatory thresholds. Weekly intake estimates for adults and children indicated that regular consumption of most contaminated water sample would exceed the tolerable weekly intake. Compared to EU regulations, none of the tap water samples exceeded the 'Sum of PFAS' parametric value of 100 ng/L, though one sample approached this limit. In addition, surface water samples from the Jizera River (n = 21) showed a wider range of PFAS, with C7-C10 PFCAs, PFBS, and perfluorooctane sulfonic acid (PFOS) in every sample, with higher PFOS concentrations at a median of 2.56 ng/L. ∑PFAS concentrations increased downstream, rising from 1.08 ng/L near the spring to 26 ng/L downstream. This comprehensive analysis highlights the need for detailed/areal monitoring to also address hidden or non-obvious sources of PFAS contamination.

Perfluorohexane sulfonate exposure caused multiple developmental abnormalities in early life of zebrafish

Perfluorohexane sulfonate (PFHxS) has been listed as a new persistent organic pollutant since 2022. Although the production and use of PFHxS are now restricted, it remains highly persistent in aquatic environments for decades. However, so far research about the toxic effects on early-life exposure of PFHxS and underlying mechanisms are still limited. In this study, we employed both wild type and specifically labeled transgenic zebrafish as model to investigate the developmental toxicity of PFHxS during early-stage exposure in zebrafish. A series of phenotypic and molecular indicators were analyzed at various time points between 24 h post-fertilization (hpf) and 7 days post-fertilization (dpf). Our data showed that the acute toxicity of PFHxS was much lower than PFOS, with a lethal concentration 50% of 508.11 ± 88.54 μM at 120 hpf. Low-dose PFHxS exposure significantly altered heart rates, blood flow, and swimming behavior in zebrafish larvae, suggesting potential cardiotoxicity and neurotoxicity of zebrafish. Data from transgenic zebrafish with specifically labeled hearts (CZ40) confirmed that PFHxS affects cardiovascular system development. PFHxS-induced changes in transgenic zebrafish with labeled liver and pancreas (CZ16) suggest that PFHxS may cause metabolic disorders and contribute to developmental defects. Gene expression analysis showed that PFHxS with potential estrogenic effect might also affect the gonadal development of zebrafish. Our study can offer an insight into the toxicity of PFHxS in aquatic environment and health risks of early-stage PFHxS exposure in humans.

Assessment of the Variability in the Occurrence of PFAS in Fish Tissues from Selected Fisheries in the Baltic Sea

In this study, the results of a comprehensive assessment of the variability in the occurrence of ten perfluorinated compounds (PFAS) in fish tissues originating from 2014 to 2019 from six fisheries in the Baltic Sea are presented. A total of 360 fish samples of three species (perch, herring and flatfish) were analysed. For the determination of PFAS, both linear and branched stereoisomers, LC-ESI-MS/MS technique preceded by simultaneous SPE isolation was validated and applied. The total concentration of all determined PFAS compounds shows that the highest levels were observed in the Szczecin Lagoon (4.8 ± 0.7 µg/kg) and the lowest in the Pomeranian Bay (1.9 ± 0.1 µg/kg). In most samples, the dominant compound was perfluorooctane sulfonic acid (PFOS). The present research enabled the assessment of the variability in the occurrence of PFAS stereoisomers in marine fish.

Mass Spectrometry Imaging for Spatial Toxicology Research

The spatial information of xenobiotics distribution, metabolism, and toxicity mechanisms in situ has drawn increasing attention in both pharmaceutical and environmental toxicology research to aid drug development and environmental risk assessments. Mass spectrometry imaging (MSI) provides a label-free, multiplexed, and high-throughput tool to characterize xenobiotics, their metabolites, and endogenous molecules in situ with spatial resolution, providing knowledge on spatially resolved absorption, distribution, metabolism, excretion, and toxicity on the molecular level. In this perspective, we briefly summarize applications of MSI in toxicology on xenobiotic distribution and metabolism, quantification, toxicity mechanisms, and biomarker discovery. We identified several challenges regarding how we can fully harness the power of MSI in both fundamental toxicology research and regulatory practices. First, how can we increase the coverage, sensitivity, and specificity in detecting xenobiotics and their metabolites in complex biological matrices? Second, how can we link the spatial molecular information of xenobiotics to toxicity consequences to understand toxicity mechanisms, predict exposure outcomes, and aid biomarker discovery? Finally, how can we standardize the MSI experiment and data analysis workflow to provide robust conclusions for regulation and drug development? With these questions in mind, we provide our perspectives on the future directions of MSI as a promising tool in spatial toxicology research.

The unique distribution pattern of PFAS in landfill organics

PFAS from degrading landfill waste partition into organic matter, leachate, and landfill gas. Driven by the limited understanding of PFAS distribution in landfill organics, we analyzed PFAS across various depths and seven spatially distinct locations within a municipal landfill. The measured PFAS concentrations in organics ranged from 6.71 to 73.06 µg kg-1, a sum of twenty-nine PFAS from six classes. Perfluorocarboxylic acids (PFCAs) and fluorotelomer carboxylic acids (FTCAs) were the dominant classes, constituting 25-82 % and 8-40 % of total PFAS at different depths. PFBA was the most dominant PFCA with a concentration range of 0.90-37.91 µg kg-1, while 5:3 FTCA was the most prevalent FTCA with a concentration of 0.26-17.99 µg kg-1. A clear vertical distribution of PFAS was observed, with significantly greater PFAS concentrations at the middle depths (20-35 ft), compared to the shallow (10-20 ft) and high depths (35-50 ft). A strong positive correlation (r > 0.50) was noted between total PFAS, total carbon, and dissolved organic matter in landfill organics. Multivariate statistical analysis inferred common sources and transformations of PFAS within the landfill. This study underscores the importance of a system-level analysis of PFAS fate in landfills, considering waste variability, chemical properties, release mechanisms, and PFAS transformations.

Development, validation, and clinical assessment of a liquid chromatography-tandem mass spectrometry serum assay for per- and polyfluoroalkyl substances (PFAS) recommended by the National Academies of Science, Engineering, and Medicine (NASEM)

Per- and polyfluoroalkyl substances (PFAS) are widely used in industry, residential, and consumer products. Studies have shown associations between high PFAS exposure and adverse health effects. In 2022, the National Academies of Science, Engineering, and Medicine (NASEM) published Guidance on PFAS Exposure, Testing, and Clinical Follow-up providing laboratory and clinical direction. The Guidance suggests nine PFAS should be measured in serum or plasma specimens and summed to provide a total PFAS concentration using a NASEM-recommended method. Follow-up clinical recommendations are based on the calculated PFAS NASEM summation. We developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method in accordance with NASEM recommendations but distinguished by the ability to separate closely related structural isomers. As part of our validation, PFAS prevalence was evaluated in a population survey comprised of clinical donor and remnant specimens (n = 1023 in total). In this study, 82.2% of the specimens had PFAS NASEM summations of 2 to < 20 ng/mL and 2.5% had a summation ≥ 20 ng/mL. The median PFAS NASEM summation was 4.65 ng/mL in this study, lower than the 7.74 ng/mL median observed in the 2017-2020 Centers for Disease Control and Prevention, National Health and Nutrition Examination Survey (n = 3072). This lower median PFAS NASEM summation may reflect a decline in PFAS population levels over time or sample population exposure differences.

Personal care product use and per- and polyfluoroalkyl substances in pregnant and lactating people in the Maternal-Infant Research on Environmental Chemicals study

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous chemicals routinely detected in personal care products (PCPs). However, few studies have evaluated the impact of PCP use on PFAS concentrations in pregnant and lactating populations.

OBJECTIVE

We investigated associations between PCP use and PFAS concentrations in prenatal plasma and human milk.

METHODS

We leveraged the Maternal-Infant Research on Environmental Chemicals (MIREC) Study to evaluate the contribution of PCP use on PFAS concentrations in prenatal plasma (6 to 13 weeks' gestation; n = 1,940) and human-milk (2 to 10 weeks' postpartum; n = 664). Participants reported frequency of use across 8 PCP categories during the 1st and 3rd trimesters, 1 to 2 days postpartum, and 2 to 10 weeks' postpartum. We used adjusted linear regression models to quantify percent differences and corresponding 95 % confidence intervals.

RESULTS

In 1st trimester pregnant people, we found higher use of nailcare products (≥once a week vs. never: perfluorooctanoic acid (PFOA): 21 % [9.7 %, 32 %]; perfluorooctane-sulfonic acid (PFOS): 11 % [0.3 %, 23 %]), fragrances (daily vs. never: PFOA: 14 % [7.8 %, 21 %]; PFOS: 7.8 % [1.3 %, 15 %]), makeup (daily vs. never: PFOA: 14 % [5.8 %, 23 %]), hair dyes (never vs. 1-2 times during pregnancy: PFOA: 8.3 % [2.4 %, 15 %]), and hair sprays or gels (daily vs. never: PFOA: 12 % [5.0 %, 19 %], PFOS: 7.1 % [0.2 %, 15 %]) were associated with higher plasma PFAS concentrations. Similar results were observed for 3rd trimester PCP use and 2 to 10 weeks' postpartum human-milk PFAS concentrations. In addition, we also found that people using colored-permanent dye 1 to 2 days postpartum had higher Sm-PFOS (18 % [2.7 %, 35 %]), PFOA (16 % [4.3 %, 29 %]), and perfluorononanoic acid (17 % [3.6 %, 33 %]) postpartum human-milk concentrations.

CONCLUSIONS

Our results show that PCP use may be a modifiable source of PFAS exposure in pregnant and lactating populations. These results along with growing scientific evidence can help inform PFAS regulation and guide individual choices to reduce PFAS exposure.

Characterization of PFOA isomers from PFAS precursors and their reductive defluorination

Perfluorooctanoic acid (PFOA) including linear and branched isomers is one of only three PFAS included in the Stockholm convention on Persistent Organic Pollutants. Unfortunately, PFOA branched isomers have received less attention than the linear due to analytical difficulties and perceived lower environmental concentrations. In this study, we revealed a environmentally relevant pathway for the formation of branched PFOA from PFAS precursors. AFFF samples showed a doubling of branched PFOA concentrations (138 mg/L) after TOP assay oxidation (307 mg/L). These findings indicate that branched PFOA may be more pervasive in the environment than previously thought. Additionally, we investigated the reductive degradability of PFOA using vitamin B12 (VB12) (a naturally occurring electron shuttle) in combination with either zero-valent zinc (ZVZ) or zero-valent iron (ZVI). Linear PFOA, as well as two branched isomers (3-methyl PFOA and 5,5-dimethyl PFOA), resisted reductive defluorination under the experimental conditions. However, all other branched isomers degraded within 10 days in the ZVZ-VB12 system. The experimental rate constants for specific PFOA isomers generally correlate with their calculated reduction potentials, except for 6-methyl PFOA. A potential defluorination pathway was proposed based on high-resolution mass spectrometry (LC-Orbitrap) and density functional theory (DFT) studies.

Multimedia and Full-Life-Cycle Monitoring Discloses the Dynamic Accumulation Rules of PFAS and Underestimated Foliar Uptake in Wheat near a Fluorochemical Industrial Park

The escalating concern of perfluoroalkyl and polyfluoroalkyl substances (PFAS), particularly at contaminated sites, has prompted extensive investigations. In this study, samples of multimedia including air, rhizosphere soil, and tissues of wheat at various growing stages were collected near a mega fluorochemical industrial park in China. Perfluorooctanoic acid (PFOA) was predominant in both air and soil with a strong correlation, highlighting air deposition as an important source in the terrestrial system. PFAS concentrations in wheat decreased in the stem and ear but increased in the leaves as wheat matured. Specifically, perfluorobutanoic acid (PFBA) dominated in the aboveground tissues in the full-life-cycle, except that PFOA surpassed and became predominant in leaves during the filling and maturing stages, hinting at an airborne source. For all PFAS, both bioaccumulation factors and translocation factors (TFs) were inversely correlated with the carbon chain length during the full-life-cycle. The obtained TF values were considerably higher than those obtained from ambient sites reported previously, further suggesting an unneglectable foliar uptake from air, which was estimated to be 25% for PFOA. Moreover, spray irrigation remarkably enhanced the absorption of PFAS in wheat via foliar uptake relative to flood irrigation. The estimated daily intake of PFBA via wheat consumption and air inhalation was 0.50 μg/kg/day for local residents, at least one magnitude higher than the corresponding threshold, suggesting an alarmingly high exposure risk.

Examining perfluorohexane sulfonate (PFHxS) impacts on sensorimotor and circadian rhythm development

Perfluorohexane sulfonate (PFHxS) is a ubiquitous perfluoroalkyl substance known for its environmental persistence and potential toxicity. This study investigated PFHxS's impact on zebrafish embryos, focusing on sensorimotor behavior, circadian rhythm disruption, and underlying molecular mechanisms. Under 24 hr dark incubations, PFHxS exposure induced concentration-dependent hyperactivity within larval photomotor response, characterized by the distinctive "O-bend" response, strong light-phase hyperactive movement and seizure-like movements. It appears that PFHxS-treated embryos cannot sense light cues in a normal manner. Similar hyperactivity was seen for acoustic startle response assay, suggesting that the response is not merely visual, but sensorimotor. LC-MS studies confirmed detectable uptake of PFHxS into embryos. We then conducted mRNA-sequencing across multiple time points (48 and 120 hpf) and concentrations (0.00025, 0.0025 and 25 µM). Data at the 25 µM (2-120 hpf) exposure showed disrupted pathways associated with DNA and cell cycle. Interestingly, data at 0.00025 µM - an environmentally relevant concentration- at 48 hpf showed disruption of MAPK and other signaling pathways. Immunohistochemistry of eyes showed reduced retinal stem cell proliferation, consistent with observed DNA replication pathway disruptions. To assess if these impacts were driven by circadian rhythm development, we manipulated light/dark cycles during PFHxS incubation; this manipulation altered behavioral patterns, implicating circadian rhythm modulation as a target of PFHxS. Since circadian rhythm is modulated by the pineal gland, we ablated the gland using metronidazole; this ablation partially rescued hyperactivity, indicating the gland's role in driving the phenotype. Collectively, these findings underscore proclivity of PFHxS to cause neurodevelopmental toxicity, necessitating further mechanistic exploration and environmental health assessments.

Spatial heterogeneity of per- and polyfluoroalkyl substances caused by glacial melting in Tibetan Lake Nam Co due to global warming

Per- and polyfluoroalkyl substances (PFASs) in high-latitude polar regions and the Tibetan Plateau have received widespread international attention. Here, we measured 18 PFASs and 11 major isomers in the lake water, sediment, and surrounding runoff of Lake Nam Co in 2020. The concentrations of ultrashort-chain trifluoroacetic acid (TFA) and perfluoropropanoic acid (PFPrA) and major isomers of perfluoooctanoic acid (PFOA) and perfluoooctane sulfonate acid (PFOS) in water bodies in high-latitude polar regions and the Tibetan Plateau are reported for the first time. The results showed that the concentration of ∑PFASs in glacial runoff was approximately 139 % greater than that in nonglacial runoff. The concentrations of ∑PFASs in the lake water and sediment in the southern lake with multiple glacial runoff events were approximately 113 % and 108 % higher, respectively, than those in the northern lake. The concentrations of short-chain perfluorobutanoic acid (PFBA) and ultrashort-chain TFA and PFPrA, which may be indicators of ice and snow melt, exhibited significant spatial heterogeneity. Overall, the spatial heterogeneity of PFAS concentrations in the water, sediment and surrounding runoff of Lake Nam Co may be caused mainly by glacial melting.

Understanding the Selective Removal of Perfluoroalkyl and Polyfluoroalkyl Substances via Fluorine-Fluorine Interactions: A Critical Review

As regulatory standards for per- and polyfluoroalkyl substances (PFAS) become increasingly stringent, innovative water treatment technologies are urgently demanded for effective PFAS removal. Reported sorbents often exhibit limited affinity for PFAS and are frequently hindered by competitive background substances. Recently, fluorinated sorbents (abbreviated as fluorosorbents) have emerged as a potent solution by leveraging fluorine-fluorine (F···F) interactions to enhance selectivity and efficiency in PFAS removal. This review delves into the designs and applications of fluorosorbents, emphasizing how F···F interactions improve PFAS binding affinity. Specifically, the existence of F···F interactions results in removal efficiencies orders of magnitude higher than other counterpart sorbents, particularly under competitive conditions. Furthermore, we provide a detailed analysis of the fundamental principles underlying F···F interactions and elucidate their synergistic effects with other sorption forces, which contribute to the enhanced efficacy and selectivity. Subsequently, we examine various fluorosorbents and their synthesis and fluorination techniques, underscore the importance of accurately characterizing F···F interactions through advanced analytical methods, and emphasize the significance of this interaction in developing selective sorbents. Finally, we discuss challenges and opportunities associated with employing advanced techniques to guide the design of selective sorbents and advocate for further research in the development of sustainable and cost-effective treatment technologies leveraging F···F interactions.

An in vitro-in silico workflow for predicting renal clearance of PFAS

Per- and poly-fluoroalkyl substances (PFAS) have a wide range of elimination half-lives (days to years) in humans, thought to be in part due to variation in proximal tubule reabsorption. While human biomonitoring studies provide important data for some PFAS, renal clearance (CLrenal) predictions for hundreds of PFAS in commerce requires experimental studies with in vitro models and physiologically-based in vitro-to-in vivo extrapolation (IVIVE). Options for studying renal proximal tubule pharmacokinetics include cultures of renal proximal tubule epithelial cells (RPTECs) and/or microphysiological systems. This study aimed to compare CLrenal predictions for PFAS using in vitro models of varying complexity (96-well plates, static 24-well Transwells and a fluidic microphysiological model, all using human telomerase reverse transcriptase-immortalized and OAT1-overexpressing RPTECs combined with in silico physiologically-based IVIVE. Three PFAS were tested: one with a long half-life (PFOS) and two with shorter half-lives (PFHxA and PFBS). PFAS were added either individually (5 μM) or as a mixture (2 μM of each substance) for 48 h. Bayesian methods were used to fit concentrations measured in media and cells to a three-compartmental model to obtain the in vitro permeability rates, which were then used as inputs for a physiologically-based IVIVE model to estimate in vivo CLrenal. Our predictions for human CLrenal of PFAS were highly concordant with available values from in vivo human studies. The relative values of CLrenal between slow- and faster-clearance PFAS were most highly concordant between predictions from 2D culture and corresponding in vivo values. However, the predictions from the more complex model (with or without flow) exhibited greater concordance with absolute CLrenal. Overall, we conclude that a combined in vitro-in silico workflow can predict absolute CLrenal values, and effectively distinguish between PFAS with slow and faster clearance, thereby allowing prioritization of PFAS with a greater potential for bioaccumulation in humans.

Quantifying levels of per- and polyfluoroalkyl Substances (PFAS) in water and serum after contamination from agricultural biosolid application

The National Academies of Sciences, Engineering, and Medicine recommends per- and polyfluoroalkyl substance (PFAS) blood testing for patients with risk of elevated exposure, and the Agency for Toxic Substances and Disease Registry (ATSDR) suggests PFAS blood testing based on exposure. Barriers to PFAS blood testing include cost, access to labs, and evolving laboratory methods. We quantify water and serum PFAS levels among a highly-exposed cohort in an area with groundwater contaminated by historical agricultural biosolid application. We compare the gold standard PFAS serum test with a commercial test and results from a one-compartment toxicokinetic model. Participants were adults (n = 30) whose household (n = 19) water had levels of the sum of six PFAS > 500 ng/L. Serum PFAS were measured using liquid chromatography-tandem mass spectrometry. Demographic and water consumption data were collected via telephone. Serum PFAS results from the commercial test were accessed via medical record. Statistical analysis included descriptive statistics and bivariate plots of serum levels. Perfluorohexanoic acid, perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorobutanesulfonic acid, perfluorohexanesulfonic acid (PFHxS), and perfluorooctanesulfonic acid (PFOS) were detected in 19 wells, and PFHpA, PFOA, PFNA, perfluorodecanoic acid, perfluoroundecanoic acid, PFHxS, and PFOS were detected in at least 19 participants' serum. In well water, PFOA and PFOS levels had geometric means (GMs) of 1749 ng/L (geometric standard deviation [GSD] 2.4) and 887 ng/L (GSD 19.7), respectively. In serum, PFOA and PFOS had GMs of 116.2 µg/L (GSD 13.5) and 58.3 µg/L (GSD 13.8), respectively. Our results are comparable with and had a wider mix of PFAS than other high-exposure cohorts. There was good agreement between the commercial and gold standard tests for PFOA, PFNA, and PFHxS, and mixed agreement between the gold standard test and modeled predictions, suggesting water-based toxicokinetic models of serum PFAS may be inadequate for assessing exposure in this population.

Soluble metal porphyrins - Zero-valent zinc system for effective reductive defluorination of branched per and polyfluoroalkyl substances (PFASs)

Nano zero-valent metals (nZVMs) have been extensively utilized for decades in the reductive remediation of groundwater contaminated with chlorinated organic compounds, owing to their robust reducing capabilities, simple application, and cost-effectiveness. Nevertheless, there remains a dearth of information regarding the efficient reductive defluorination of linear or branched per- and polyfluoroalkyl substances (PFASs) using nZVMs as reductants, largely due to the absence of appropriate catalysts. In this work, various soluble porphyrin ligands [[meso‑tetra(4-carboxyphenyl)porphyrinato]cobalt(III)]Cl·7H2O (CoTCPP), [[meso‑tetra(4-sulfonatophenyl) porphyrinato]cobalt(III)]·9H2O (CoTPPS), and [[meso‑tetra(4-N-methylpyridyl) porphyrinato]cobalt(II)](I)4·4H2O (CoTMpyP) have been explored for defluorination of PFASs in the presence of the nZn0 as reductant. Among these, the cationic CoTMpyP showed best defluorination efficiencies for br-perfluorooctane sulfonate (PFOS) (94%), br-perfluorooctanoic acid (PFOA) (89%), and 3,7-Perfluorodecanoic acid (PFDA) (60%) after 1 day at 70 °C. The defluorination rate constant of this system (CoTMpyP-nZn0) is 88-164 times higher than the VB12-nZn0 system for the investigated br-PFASs. The CoTMpyP-nZn0 also performed effectively at room temperature (55% for br-PFOS, 55% for br-PFOA and 25% for 3,7-PFDA after 1day), demonstrating the great potential of in-situ application. The effect of various solubilizing substituents, electron transfer flow and corresponding PFASs defluorination pathways in the CoTMpyP-nZn0 system were investigated by both experiments and density functional theory (DFT) calculations. SYNOPSIS: Due to the unavailability of active catalysts, available information on reductive remediation of PFAS by zero-valent metals (ZVMs) is still inadequate. This study explores the effective defluorination of various branched PFASs using soluble porphyrin-ZVM systems and offers a systematic approach for designing the next generation of catalysts for PFAS remediation.

Levels and spatial profile of per- and polyfluoroalkyl substances in edible shrimp products from Japan and neighboring countries; a potential source of dietary exposure to humans

Exposure to per- and polyfluoroalkyl substances (PFAS) is of great concern for human health because of their persistence and potentially adverse effects. Dietary intake, particularly through aquatic products, is a significant route of human exposure to PFAS. We analyzed perfluoroalkyl sulfonic acid (PFSA with carbon numbers from 6 to 8 and 10 (C６-C8, C10)) and perfluorooctanesulfonamide (FOSA), and perfluoroalkyl carboxylic acid (PFCA with carbon numbers from 6 to 15 (C6-C15)) in 30 retail packs of edible shrimps, which included seven species from eight coastal areas of Japan and neighboring countries. The most prevalent compounds were perfluorooctane sulfonate (PFOS, C8) and perfluoroundecanoic acid (PFUnDA, C11), accounting for 46 % of total PFAS. The concentrations ranged from 6.5 to 44 ng/g dry weight (dw) (equivalent to 1.5 to 10 ng/g wet weight (ww)) and varied according to species and location. For example, Alaskan pink shrimp (Pandalus eous) from the Hokuriku coast, Japan contained high levels of long-chain PFCAs (38 ng/g dw (equivalent to 8.7 ng/g ww)), while red rice prawn (Metapenaeopsis barbata) from Yamaguchi, Japan contained a high concentration of PFOS (29 ng/g dw (equivalent to 6.7 ng/g ww)). We also observed regional differences in the PFAS levels with higher concentrations of long-chain PFCAs in Japanese coastal waters than in the South China Sea. The PFAS profiles in shrimp were consistent with those in the diet and serum of Japanese consumers, suggesting that consumption of seafood such as shrimp may be an important source of exposure. The estimated daily intake of sum of all PFAS from shrimp from Japanese coastal water was 0.43 ng/kg body weight/day in average, which could reach the weekly tolerable values (4.4 ng/kg body weight /week) for the sum of the four PFSA set by the EFSA for heavy consumers. The high concentration of PFAS in shrimp warrants further investigation.

Roles of varying carbon chains and functional groups of legacy and emerging per-/polyfluoroalkyl substances in adsorption on metal-organic framework: Insights into mechanism and adsorption prediction

Metal-organic frameworks (MOFs) are promising adsorbents for legacy per-/polyfluoroalkyl substances (PFASs), but they are being replaced by emerging PFASs. The effects of varying carbon chains and functional groups of emerging PFASs on their adsorption behavior on MOFs require attention. This study systematically revealed the structure-adsorption relationships and interaction mechanisms of legacy and emerging PFASs on a typical MOF MIL-101(Cr). It also presented an approach reflecting the average electronegativity of PFAS moieties for adsorption prediction. We demonstrated that short-chain or sulfonate PFASs showed higher adsorption capacities (μmol/g) on MIL-101(Cr) than their long-chain or carboxylate counterparts, respectively. Compared with linear PFASs, their branched isomers were found to exhibit a higher adsorption potential on MIL-101(Cr). In addition, the introduction of ether bond into PFAS molecule (e.g., hexafluoropropylene oxide dimeric acid, GenX) increased the adsorption capacity, while the replacement of CF2 moieties in PFAS molecule with CH2 moieties (e.g., 6:2 fluorotelomer sulfonate, 6:2 FTS) caused a decrease in adsorption. Divalent ions (such as Ca2+ and SO42-) and solution pH have a greater effect on the adsorption of PFASs containing ether bonds or more CF2 moieties. PFAS adsorption on MIL-101(Cr) was governed by electrostatic interaction, complexation, hydrogen bonding, π-CF interaction, and π-anion interaction as well as steric effects, which were associated with the molecular electronegativity and chain length of each PFAS. The average electronegativity of individual moieties (named Me) for each PFAS was estimated and found to show a significantly positive correlation with the corresponding adsorption capacity on MIL-101(Cr). The removal rates of major PFASs in contaminated groundwater by MIL-101(Cr) were also correlated with the corresponding Me values. These findings will assist with the adsorption prediction for a wide range of PFASs and contribute to tailoring efficient MOF materials.

Evaluation and prediction of anthropogenic impacts on long-term multimedia fate and health risks of PFOS and PFOA in the Elbe River Basin

Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) have aroused great concern owing to their widespread occurrence and toxic effects. However, their long-term trends and multimedia fate remain largely unknown. Here, we investigate the spatiotemporal characteristics and periodic oscillations of PFOS and PFOA in the Elbe River between 2010 and 2021. Anthropogenic emission inventories and multimedia fugacity model were developed to analyse their historical and future transport fates and quantify related human risks in each medium for the three age groups. The results show that average PFOS and PFOA concentrations in the Elbe River were 4.08 and 3.41 ng/L, declining at the annual rate of 7.36% and 4.98% during the study period, respectively. Periodic oscillations of their concentrations and mass fluxes were most pronounced at 40-60 and 20-40 months. The multimedia fugacity model revealed that higher concentrations occurred in fish (PFOS: 14.29, PFOA: 0.40 ng/g), while the soil was their dominant sink (PFOS: 179, PFOA: 95 tons). The exchange flux between water and sediment was the dominant pathway in multimedia transportation (397 kg/year). Although PFOS and PFOA concentrations are projected to decrease by 22.41% and 50.08%, respectively, from 2021 to 2050, the hazard quotient of PFOS in fish is a low hazard. This study provides information for the assessment of PFOS and PFOA pollution in global watersheds and the development of related mitigation policies, such as banning fish predation in polluted rivers, to mitigate their risks.

Time Is Ripe for Targeting Per- and Polyfluoroalkyl Substances-Induced Hormesis: Global Aquatic Hotspots and Implications for Ecological Risk Assessment

Globally implemented ecological risk assessment (ERA) guidelines marginalize hormesis, a biphasic dose-response relationship characterized by low-dose stimulation and high-dose inhibition. The present study illuminated the promise of hormesis as a scientific dose-response model for ERA of per- and polyfluoroalkyl substances (PFAS) represented by perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). A total of 266 hormetic dose-response relationships were recompiled from 1237 observations, covering 30 species from nine representative taxonomic groups. The standardized hormetic amplitudes followed the log-normal probability distribution, being subject to the limits of biological plasticity but independent of stress inducers. The SHapley Additive exPlanations algorithm revealed that the target endpoint was the most important variable explaining the hormetic amplitudes. Subsequently, quantitative frameworks were established to incorporate hormesis into the predicted no-effect concentration levels, with a lower induction dose and a zero-equivalent point but a broader hormetic zone for PFOS. Realistically, 10,117 observed concentrations of PFOA and PFOS were gathered worldwide, 4% of which fell within hormetic zones, highlighting the environmental relevance of hormesis. Additionally, the hormesis induction potential was identified in other legacy and emerging PFAS as well as their alternatives and mixtures. Collectively, it is time to incorporate the hormesis concept into PFAS studies to facilitate more realistic risk characterizations.

Influence of soil composition and environmental factors on the adsorption of per- and polyfluoroalkyl substances: A review

Per- and polyfluoroalkyl substances (PFASs) have garnered considerable scientific and regulatory scrutiny due to their widespread distribution across environments and their potential toxicological impacts on human health. The pedosphere serves as a vital reservoir for these chemicals, significantly determining their environmental trajectory and chemical transformations. This study offers a comprehensive synthesis of the current understanding regarding the adsorption mechanics of PFASs in soil matrices. Due to their unique molecular structure, PFASs predominantly engage in hydrophobic and electrostatic interactions during soil adsorption. This work thoroughly evaluates the influence of various factors on adsorption efficiency, including soil properties, molecular characteristics of PFASs, and the prevailing environmental conditions. The complex nature of soil environments complicates isolating individual impacts on PFAS behavior, necessitating an integrated approach to understanding their environmental destinies better. Through this exploration, we seek to clarify the complex interplay of factors that modulate the adsorption of PFASs in soils, highlighting the urgent need for future research to disentangle the intricate and combined effects that control the environmental behavior of PFAS compounds.

Extraordinary levels of per- and polyfluoroalkyl substances (PFAS) in vertebrate animals at a New Mexico desert oasis: Multiple pathways for wildlife and human exposure

Per- and polyfluoroalkyl substances (PFAS) in the environment pose persistent and complex threats to human and wildlife health. Around the world, PFAS point sources such as military bases expose thousands of populations of wildlife and game species, with potentially far-reaching implications for population and ecosystem health. But few studies shed light on the extent to which PFAS permeate food webs, particularly ecologically and taxonomically diverse communities of primary and secondary consumers. Here we conducted >2000 assays to measure tissue-concentrations of 17 PFAS in 23 species of mammals and migratory birds at Holloman Air Force Base (AFB), New Mexico, USA, where wastewater catchment lakes form biodiverse oases. PFAS concentrations were among the highest reported in animal tissues, and high levels have persisted for at least three decades. Twenty of 23 species sampled at Holloman AFB were heavily contaminated, representing middle trophic levels and wetland to desert microhabitats, implicating pathways for PFAS uptake: ingestion of surface water, sediments, and soil; foraging on aquatic invertebrates and plants; and preying upon birds or mammals. The hazardous long carbon-chain form, perfluorooctanosulfonic acid (PFOS), was most abundant, with liver concentrations averaging >10,000 ng/g wet weight (ww) in birds and mammals, respectively, and reaching as high 97,000 ng/g ww in a 1994 specimen. Perfluorohexanesulfonic acid (PFHxS) averaged thousands of ng/g ww in the livers of aquatic birds and littoral-zone house mice, but one order of magnitude lower in the livers of upland desert rodent species. Piscivores and upland desert songbirds were relatively uncontaminated. At control sites, PFAS levels were strikingly lower on average and different in composition. In sum, legacy PFAS at this desert oasis have permeated local aquatic and terrestrial food webs across decades, severely contaminating populations of resident and migrant animals, and exposing people via game meat consumption and outdoor recreation.

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

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

Application of electron beam technology to decompose per- and polyfluoroalkyl substances in water

The widespread detection of per- and polyfluoroalkyl substances (PFAS) in environmental compartments across the globe has raised several health concerns. Destructive technologies that aim to transform these recalcitrant PFAS into less toxic, more manageable products, are gaining impetus to address this problem. In this study, a 9 MeV electron beam accelerator was utilized to treat a suite of PFAS (perfluoroalkyl carboxylates: PFCAs, perfluoroalkyl sulfonates, and 6:2 fluorotelomer sulfonate: FTS) at environmentally relevant levels in water under different operating and water quality conditions. Although perfluorooctanoic acid and perfluorooctane sulfonic acid showed >90% degradation at <500 kGy dose at optimized conditions, a fluoride mass balance revealed that complete defluorination occurred only at/or near 1000 kGy. Non-target and suspect screening revealed additional degradation pathways differing from previously reported mechanisms. Treatment of PFAS mixtures in deionized water and groundwater matrices showed that FTS was preferentially degraded (∼90%), followed by partial degradation of long-chain PFAS (∼15-60%) and a simultaneous increase of short-chain PFAS (up to 20%) with increasing doses. The increase was much higher (up to 3.5X) in groundwaters compared to deionized water due to the presence of PFAS precursors as confirmed by total oxidizable precursor (TOP) assay. TOP assay of e-beam treated samples did not show any increase in PFCAs, confirming that e-beam was effective in also degrading precursors. This study provides an improved understanding of the mechanism of PFAS degradation and revealed that short-chain PFAS are more resistant to defluorination and their levels and regulation in the environment will determine the operating conditions of e-beam and other PFAS treatment technologies.

PFAS occurrence and distribution in yard waste compost indicate potential volatile loss, downward migration, and transformation

We discovered high concentrations of PFAS (18.53 ± 1.5 μg kg-1) in yard waste compost, a compost type widely acceptable to the public. Seventeen out of forty targeted PFAS, belonging to six PFAS classes were detected in yard waste compost, with PFCAs (13.51 ± 0.99 μg kg-1) and PFSAs (4.13 ± 0.19 μg kg-1) being the dominant classes, comprising approximately 72.5% and 22.1% of the total measured PFAS. Both short-chain PFAS, such as PFBA, PFHxA, and PFBS, and long-chain PFAS, such as PFOA and PFOS, were prevalent in all the tested yard waste compost samples. We also discovered the co-occurrence of PFAS with low-density polyethylene (LDPE) and polyethylene terephthalate (PET) plastics. Total PFAS concentrations in LDPE and PET separated from incoming yard waste were 7.41 ± 0.41 μg kg-1 and 1.35 ± 0.1 μg kg-1, which increased to 8.66 ± 0.81 μg kg-1 in LDPE and 5.44 ± 0.56 μg kg-1 in PET separated from compost. An idle mature compost pile revealed a clear vertical distribution of PFAS, with the total PFAS concentrations at the surface level approximately 58.9-63.2% lower than the 2 ft level. This difference might be attributed to the volatile loss of short-chain PFCAs, PFAS's downward movement with moisture, and aerobic transformations of precursor PFAS at the surface.

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

Background

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

Methods

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

Results

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

Conclusions

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

Per- and polyfluoroalkyl substances in waterbird feathers around Poyang Lake, China: Compound and species-specific bioaccumulation

As a nondestructive means of environmental monitoring, bird feathers have been used to analyze levels of per- and polyfluoroalkyl substances (PFASs) in specific environments. In this study, feather samples from 10 waterbird species around Poyang Lake were collected, and a pretreatment method for PFASs in feathers was optimized. The results showed that a combined cleaning method using ultrapure water and n-hexane effectively removed external PFASs. Twenty-three legacy and emerging PFASs were identified in the feathers of waterbirds, of which hexafluoropropylene oxides (HFPOs), chlorinated polyfluoroalkyl ether sulfonates (Cl-PFESAs), and sodium p-perfluorinated noneoxybenzene sulfonate (OBS) were reported for the first time, with their concentrations ranging from 0.060-2.4 ng·g-1 dw, 0.046-30 ng·g-1 dw, and lower than the method detection limit to 30 ng·g-1 dw, respectively. Compound- and species-specific bioaccumulation of PFASs was observed in the feathers of different waterbird species, suggesting that different PFAS types can be monitored through the selection of different species. Moreover, the concentrations of most PFCAs (except perfluorobutyric acid), perfluorooctane sulfonate (PFOS), and perfluorooctane sulfonamide (FOSA) were significantly positively correlated with δ15N (p < 0.05), while the concentrations of HFPOs, Cl-PFESAs, and OBS had significant positive correlations with δ13C. This indicates that the bioaccumulation of legacy and emerging PFASs in waterbird feathers is affected by their trophic level, feeding habits, and foraging area.

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.

Spatial distribution, isomer signature and air-soil exchange of legacy and emerging poly- and perfluoroalkyl substances

Widespread occurrences of various poly- and perfluoroalkyl substances (PFAS) in terrestrial environment calls for the growing interest in their transport behaviors. However, limited studies detected PFAS with structural diversity in tree barks, which reflect the long-term contamination in atmosphere and play a vital role in air-soil exchange behaviors. In this study, 26 PFAS congeners and typical branched isomers were investigated in surface soils and tree barks at 28 sites along the Taihu Lake, Taipu River, and Huangpu River. Concentrations of total PFAS in soils and tree barks were 0.991-29.4 and 7.99-188 ng/g dw, with PFPeA and PFDoA were the largest contributors in the two matrices. The highest PFAS levels were found in the Taihu Lake watershed, where textile manufacturing and metal plating activities highly prosper. With regard to the congener and isomer signatures, short-chain homologs dominated in soils (65.5%), whereas long-chain PFAS showed a major proportion in barks (41.9%). The composition of linear isomers of PFOS, PFOA and PFHxS implied that precursor degradation might be an important source of PFAS in addition to the 3M electrochemical fluorination (ECF). Additionally, the distance from the emission source, total organic carbon (TOC), logKOA and logKOW were considered potential influencing factors in PFAS distributions. Based on the multi-media fugacity model, about 71% of the fugacity fraction (ffs) values of the PFAS were below 0.3, indicating the dominant deposition from the atmosphere to the soil. The average fluxes of air-soil exchange for PFAS were -0.700 ± 11.0 ng/(m2·h). Notably, the estimated daily exposure to PFAS ranged from 9.57 × 10-2 to 8.59 × 10-1 ng/kg·bw/day for children and 3.31 × 10-2 to 3.09 × 10-1 ng/kg·bw/day for adults, suggesting low risks from outdoor inhalation and dermal uptake. Overall, results from distribution with structural diversity, air-soil exchange and preliminary risk assessment. This study provided in-depth insight of PFAS in multi-medium environment and bridged gaps between field data and policy-making for pollution control.

Impact of Environmental Exposures on Human Breast Milk Lipidome in Future Immune-Mediated Diseases

The composition of human breast milk (HBM) exhibits significant variability both between individuals and within the same individual. While environmental factors are believed to play a role in this variation, their influence on breast milk composition remains inadequately understood. Herein, we investigate the impact of environmental factors on HBM lipid composition in a general population cohort. The study included mothers (All Babies In Southeast Sweden study) whose children later progressed to one or more immune-mediated diseases later in life: type 1 diabetes (n = 9), celiac disease (n = 24), juvenile idiopathic arthritis (n = 9), inflammatory bowel disease (n = 7), hypothyroidism (n = 6), and matched controls (n = 173). Lipidome of HBM was characterized by liquid chromatography combined with high-resolution mass spectrometry. We observed that maternal age, body mass index, diet, and exposure to perfluorinated alkyl substances (PFASs) had a marked impact on breast milk lipidome, with larger changes observed in the milk of those mothers whose children later developed autoimmune diseases. We also observed differences in breast milk lipid composition in those mothers whose offspring later developed autoimmune diseases. Our study suggests that breast milk lipid composition is modified by a complex interaction between genetic and environmental factors, and, importantly, this impact was significantly more pronounced in those mothers whose offspring later developed autoimmune/inflammatory diseases. Our findings also suggest that merely assessing PFAS concentration may not capture the full extent of the impact of chemical exposures; thus, the more comprehensive exposome approach is essential for accurately assessing the impact of PFAS exposure on HBM and, consequently, on the health outcomes of the offspring.

Environment relevant exposure of perfluorooctanoic acid accelerates the growth of hepatocellular carcinoma cells through mammalian target of rapamycin (mTOR) signal pathway

Perfluorooctanoic acid (PFOA), a synthetic alkyl chain fluorinated compound, has emerged as a persistent organic pollutant of grave concern, casting a shadow over both ecological integrity and humans. Its insidious presence raises alarms due to its capacity to bioaccumulate within the human liver, potentially paving the treacherous path toward liver cancer. Yet, the intricate mechanisms underpinning PFOA's role in promoting the growth of hepatocellular carcinoma (HCC) remain shrouded in ambiguity. Here, we determined the proliferation and transcription changes of HCC after PFOA exposure through integrated experiments including cell culture, nude mice tests, and colony-forming assays. Based on our findings, PFOA effectively promotes the proliferation of HCC cells within the experimental range of concentrations, both in vivo and in vitro. The proliferation efficiency of HCC cells was observed to increase by approximately 10% due to overexposure to PFOA. Additionally, the cancer weight of tumor-bearing nude mice increased by 87.0% (p < 0.05). We systematically evaluated the effects of PFOA on HCC cells and found that PFOA's exposure can selectively activate the PI3K/AKT/mTOR/4E-BP1 signaling pathway, thereby playing a pro-cancer effect on HCC cells Confirmation echoed through western blot assays and inhibitor combination analyses. These insights summon a response to PFOA's dual nature as both an environmental threat and a promoter of liver cancer. Our work illuminates the obscured domain of PFOA-induced hepatoxicity, shedding light on its ties to hepatocellular carcinoma progression.

Fixed-bed adsorption studies of endocrine-disrupting compounds from water by using novel calcium-based metal-organic frameworks

The presence of emerging water pollutants such as endocrine-disrupting compounds (EDCs), including 17-ethynylestradiol (EE2), bisphenol A (BPA), and perfluorooctanoic acid (PFOA), in contaminated water sources poses significant environmental and health challenges. This study aims to address this issue by investigating the efficiency of novel calcium-based metal-organic frameworks, known as mixed-linker calcium-based metal-organic frameworks (Ca-MIX), in adsorbing these endocrine-disrupting compounds. This study analyzed the influence of influent concentration, bed height, and flow rate on pollutant removal, with bed height emerging as a crucial factor. From the breakthrough curves, it was determined that the column maximum adsorption capacities followed the order of 17-ethynylestradiol (101.52 μg/g; 40%) > bisphenol A (99.07 μg/g; 39%) > perfluorooctanoic acid (81.28 μg/g; 32%). Three models were used to predict the adsorption process, with the Yan model outperforming the other models. This suggests the potential of mixed-linker calcium-based metal-organic frameworks for removing endocrine-disrupting compounds from water, using the Yan model as an effective predictor. Overall, this study provides valuable insights for the development of effective water treatment methods using mixed-linker calcium-based metal-organic frameworks to remove endocrine-disrupting compounds from contaminated water sources.

Porous polypyrrole with a vesicle-like structure for efficient removal of per- and polyfluoroalkyl substances from water: Crucial role of porosity and morphology

Herein, a vesicle-like and porous polypyrrole (pPPy) was fabricated by in suit self-template method to efficiently capture per- and polyfluoroalkyl substances (PFASs) and the important role of porosity and morphology in PFAS removal was explored. Compared to solid PPy (sPPy), the porosity and vesicle-like morphology of pPPy endowed it with excellent properties such as large specific surface area (108.9 m2/g vs. 22.3 m2/g), suitable pore sizes (17.4 nm), dispersity, and high hydrophilicity, which facilitated mass transfer and enhanced PFAS sorption performance. The estimated sorption capacities of pPPy for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) were 509 mg/g and 532 mg/g, respectively, which were ∼2 times higher than sPPy. Furthermore, pPPy demonstrated PFAS removal of ≥ 90% across a wide pH range (3-9) and varying humic acid concentrations (0-50 mg/L). In actual water matrices, pPPy efficiently removed 12 short-chain (C-F number: 3-6) and long-chain PFASs (>90% removal for major PFASs), outperforming sPPy by ∼1.2-2.5 times. Notably, the enlarged porosity and regular morphology of pPPy significantly enhanced the removal of short-chain PFASs by ∼2 times. The spent pPPy could be regenerated and reused over 5 times. This research provides valuable insights for designing efficient PFAS sorbents by emphasizing control over porosity and morphology.

Delineation of a PFOA Plume and Assessment of Data Gaps in its Conceptual Model Using PlumeSeeker™

An accurate conceptual site model (CSM) and plume-delineation at contamination sites are pre-requisites for successful remediation and for satisfying regulators and stakeholders. PlumeSeeker™ is well-suited for assessing data gaps in CSMs by using available site data and for identifying the optimal number and locations of sampling locations to delineate contaminant plumes. It is an enhancement of a university research code for plume delineation using geostatistical and stochastic modeling integrated with the groundwater modeling software MODFLOW-SURFACT™. PlumeSeeker™ increases the overall confidence in the location of the plume boundary through a variance-reduction approach that selects existing- or new monitoring wells for sampling based on minimizing the uncertainty in plume boundary and on new field information. Applicable at sites with or without existing monitoring wells, PlumeSeeker™ is particularly powerful for optimally allocating project resources (labor, well installation, and laboratory costs) between existing wells and sampling at new locations. An application of PlumeSeeker™ at Lakehurst, the naval component of Joint Base McGuire-Dix-Lakehurst in New Jersey, demonstrates how the cost of delineating the migration pathway of a perfluorooctanoic acid (PFOA) plume can be minimized by requiring only 9 new sampling locations in addition to samples from 2 existing wells for achieving a 70% reduction in plume uncertainty. In addition, the use of available site data in three different scenarios identified CSM data-gaps in the source area and in the interaction between Manapaqua Branch and groundwater, where the observed high concentration in this area could have resulted from a combination of groundwater migration and induced infiltration.

Predicting molecular docking of per- and polyfluoroalkyl substances to blood protein using generative artificial intelligence algorithm DiffDock

This study computationally evaluates the molecular docking affinity of various perfluoroalkyl and polyfluoroalkyl substances (PFAs) towards blood proteins using a generative machine-learning algorithm, DiffDock, specialized in protein-ligand blind-docking learning and prediction. Concerns about the chemical pathways and accumulation of PFAs in the environment and eventually in the human body has been rising due to empirical findings that levels of PFAs in human blood has been rising. DiffDock may offer a fast approach in determining the fate and potential molecular pathways of PFAs in human body.

In vitro modeling of the post-ingestion bioaccessibility of per- and polyfluoroalkyl substances sorbed to soil and house dust

Per- and polyfluoroalkyl substances (PFAS) are regularly found in soils and dusts, both of which can be consumed by children at relatively high amounts. However, there is little data available to model the bioaccessibility of PFAS in soils and dusts when consumed or to describe how the physiochemical properties of PFAS and soils/dusts might affect bioaccessibility of these chemicals. Because bioaccessibility is an important consideration in estimating absorbed dose for exposure and risk assessments, in the current study, in vitro assays were used to determine bioaccessibility of 14 PFAS in 33 sets of soils and dusts. Bioaccessibility assays were conducted with and without a sink, which was used to account for the removal of PFAS due to their movement across the human intestine. Multiple linear regression with backward elimination showed that a segmented model using PFAS chain length, number of branches, and percent total organic carbon explained 78.0%-88.9% of the variability in PFAS bioaccessibility. In general, PFAS had significantly greater bioaccessibility in soils relative to dusts and the addition of a sink increased bioaccessibility in the test system by as much as 10.8% for soils and 20.3% for dusts. The results from this study indicate that PFAS bioaccessibility in soils and dusts can be predicted using a limited set of physical chemical characteristics and could be used to inform risk assessment models.

Biological Aging Acceleration Due to Environmental Exposures: An Exciting New Direction in Toxicogenomics Research

Biological clock technologies are designed to assess the acceleration of biological age (B-age) in diverse cell types, offering a distinctive opportunity in toxicogenomic research to explore the impact of environmental stressors, social challenges, and unhealthy lifestyles on health impairment. These clocks also play a role in identifying factors that can hinder aging and promote a healthy lifestyle. Over the past decade, researchers in epigenetics have developed testing methods that predict the chronological and biological age of organisms. These methods rely on assessing DNA methylation (DNAm) levels at specific CpG sites, RNA levels, and various biomolecules across multiple cell types, tissues, and entire organisms. Commonly known as 'biological clocks' (B-clocks), these estimators hold promise for gaining deeper insights into the pathways contributing to the development of age-related disorders. They also provide a foundation for devising biomedical or social interventions to prevent, reverse, or mitigate these disorders. This review article provides a concise overview of various epigenetic clocks and explores their susceptibility to environmental stressors.

Biomagnification and temporal trends (1990-2021) of perfluoroalkyl substances in striped dolphins (Stenella coeruleoalba) from the NW Mediterranean sea

Poly- and Perfluoroalkyl Substances (PFAS) are a well-known class of pollutants which can bioaccumulate and biomagnify with a vast majority being highly persistent. This study aims to determine the biomagnification rates of PFAS in sexually mature striped dolphins and to assess temporal trends on PFAS concentrations over the past three decades (1990-2021) in the North-Western Mediterranean Sea. Thirteen and 17 of the 19 targeted PFAS were detected in the samples of the dolphins' digestive content and liver, respectively, at concentrations ranging between 43 and 1609 ng/g wet weight, and 254 and 7010 ng/g wet weight, respectively. The most abundant compounds in both types of samples were linear perfluorooctanesulfonic acid (n-PFOS) and perfluorooctanesulfonamide (FOSA), which were present in all samples, followed by perfluoroundecanoic acid (PFUnDA), perfluorotridecanoic acid (PFTrDA) and perfluorononanoic acid (PFNA). Long-chain PFAS (i.e., PFCAs C ≥ 7 and PFSAs C ≥ 6) biomagnified to a greater extent than short-chain PFAS, suggesting a potential effect on the health of striped dolphins. Environmental Quality Standards concentrations set in 2014 by the European Union were exceeded in half of the samples of digestive content, suggesting that polluted prey may pose potential health risks for striped dolphins. Concentrations of most long-chain PFAS increased from 1990 to 2004-2009, then stabilized during 2014-2021, possibly following country regulations and industrial initiatives. The current study highlights the persistent presence of banned PFAS and may contribute to future ecological risk assessments and the design of management strategies to mitigate PFAS pollution in marine ecosystems.

Optimization for the analysis of 42 per- and polyfluorinated substances in human plasma: A high-throughput method for epidemiological studies

There is an increasing awareness about the presence of per- and polyfluoroalkyl substances (PFAS) in many environmental and biological compartments, including human biofluids and tissues. However, the increase of PFAS replacements, including alternatives with shorter chain or less bioaccumulative potential, has broaden the exposure and the need for wider identification procedures. Moreover, the low volumes available for human blood or plasma, and the high number of samples needed to assess adequately epidemiologic studies, require particularly fast, reproducible and, if possible, miniaturized protocols. Therefore, accurate and robust analytical methods are still needed to quantify the PFAS's burden in humans and to understand potential health risks. In this study, we have developed and validated the analysis of 42 PFAS in human plasma by means of a Captiva 96-well micro extraction plate and a LC-q-Orbitrap. For the optimization of the analytical workflow, three extraction/clean-up methods were tested, and the selected one was validated using spiked artificial and bovine plasma at four concentration levels. The final method showed high absolute recoveries for the 42 PFAS, ranging from 52% to 130%, instrumental detection limits between 0.001-0.6 ng mL-1, overall good precision (CV < 20% for most of the PFAS) and a low uncertainty (< 30% of relative expanded deviation, k = 2). The method was further validated both with the NIST plasma Standard Reference Material 1950, showing that the accuracy of the provided results was between 63%-101%, and by the proficiency test arranged by the Arctic Monitoring Assessment Program (AMAP, 2022) obtaining satisfactory results within 95% confidence interval of the assigned value.