Bioaccumulation of perfluorinated alkyl acids: observations and models

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.

Effects of dissolved cations, dissolved organic carbon, and exposure concentrations on per- and polyfluoroalkyl substances bioaccumulation in freshwater algae

Per- and polyfluoroalkyl substances (PFAS) have attracted global attention because of their persistence, toxicity, bioaccumulation potential, and associated adverse effects. As important primary producers, freshwater algae constitute the base of the food web in freshwater aquatic ecosystems. However, the effects of key environmental factors on PFAS uptake and bioaccumulation in freshwater algae have not been thoroughly studied. In this study, three bioaccumulation experiments were conducted to evaluate the influence of dissolved cations, dissolved organic carbon, and exposure concentrations on PFAS bioaccumulation in algae. Among the 14 studied PFAS, seven long-chain PFAS tended to bioaccumulate in algae. Elevated divalent cations (Ca2+ and Mg2+) and dissolved organic carbon did not significantly change the algal bioconcentration factors (BCFs) of PFAS, suggesting complexity of the interactions among PFAS, environmental factors, and biotic activities. Additionally, increasing exposure concentrations (0.5, 1, 5, and 10 μg/L of each PFAS) increased PFAS concentrations in algae but decreased the BCF values. This indicated that attention should be paid to the application of BCFs in future studies, including ecological risk assessment. Moreover, fluorotelomer sulfonic acids (FTSs) were incompletely recovered, suggesting that biotransformation occurred. Further studies should be conducted to evaluate whether algae play a role in FTSs biotransformation and to determine the mechanisms. Studying the impacts of key environmental factors on PFAS bioaccumulation in algae is crucial for understanding the bioaccumulation processes that occur at the lowest trophic level and that eventually affect the dynamics of entire aquatic ecosystems.

Screening estimates of bioaccumulation factors for 4950 per- and polyfluoroalkyl substances in aquatic species

The considerable variability in bioaccumulation factors (BAFs) of per- and polyfluoroalkyl substances (PFAS) across aquatic species, driven by the diversity of PFAS, complex water conditions, and species differences, underscores the resource-intensive nature of relying on experimental data. To develop a robust and effective approach for predicting BAFs, a predictive framework using a three-level stacking deep ensemble learning model was established. Initially, we compiled a substantial dataset of BAFs, encompassing a wide variety of PFAS across both marine and freshwater species. The stacking model demonstrated strong performance, achieving R-squared (R2) values of 0.94 and 0.89, and root-mean-square errors (RMSE) of 0.88 and 1.17 for training and testing, respectively. External validation revealed that 60 % and 90 % of predictions fell within 2-fold and 4-fold differences, respectively, from the observed values. Using this model, we predicted BAFs for 4950 PFAS in 54 global edible fish species, with the predicted median BAF values ranging from 22 L/kg to 477.09 L/kg. The results indicated that PFAS with multiple functional groups (e.g., benzene rings and ketones) exhibited higher BAFs. Finally, an accessible online tool (https://pfasbaf.hhra.net/) was launched to facilitate BAF predictions. This newly released application promises to offer valuable support for environmental risk management and policymaking efforts.

Estimation of species- and sex-specific PFAS pharmacokinetics in mice, rats, and non-human primates using a Bayesian hierarchical methodology

The carbon chain length, degree of fluorination, and functional group of per- and polyfluoroalkyl substances (PFAS) influences the bioaccumulation and half-lives of these substances in humans and laboratory animals. Pharmacokinetic (PK) studies using laboratory animals characterize the absorption, distribution, metabolism, and excretion (ADME) of a PFAS and can provide the underlying data for inter-species extrapolation to inform human pharmacokinetics. However, variations in ADME arise due to differences in protein binding and renal and hepatobiliary clearance mechanisms. In particular, sex- and species-specific differences in active transporter abundance and PFAS binding affinity challenge body weight-based extrapolation assumptions from animal models to human PK parameters. Because these protein-dependent changes in ADME do not always scale with species body weight, classic allometric scaling assumptions can fail to account for species-specific transporter-mediated clearance. In addition, study-dependent differences in pharmacokinetic modeling approaches and parameterization techniques can result in large differences among the PK parameters reported in the literature. To better quantify PFAS pharmacokinetics and characterize the underlying uncertainty, we implemented a Bayesian inference hierarchical model to estimate PFAS PK parameters for multiple species (mice, rats, and non-human primates) using numerous single-dose animal studies. Through an alternative parameterization of the one- and two-compartment models, this method improved parameter identifiability and allowed for the use of prior information on PFAS absorption rate, clearance, and volume of distribution. Using reported time-course concentration data, we estimated sex-specific clearance, volume of distribution, and half-life across mice, rats, and non-human primates using a consistent modeling methodology for eight PFAS: PFHxA, PFHxS, PFNA, PFDA, PFBS, PFBA, PFOA, and PFOS. The resulting comparison to available human data demonstrated that standard volume of distribution body-mass scaling (BW1) for PFAS generally agrees with reported human values while standard assumptions for allometric scaling of clearance (BW3/4) are not appropriate for most of the PFAS investigated in this study. In addition, we demonstrated that there may be considerable differences in clearance for PFAS in some species when comparing across different sexes and routes of exposure.

Accumulation of per- and polyfluoroalkyl substances (PFAS) in tissues of wild boar (Sus scrofa)

The widespread application of per- and polyfluoroalkyl substances (PFAS) resulted in ubiquitous environmental contamination. Understanding the PFAS tissue distribution in mammals and humans is crucial for the assessment of potential health risks. The levels of eleven PFAS were determined by UPLC-MS/MS in plasma and various tissues of wild boar (n = 82) hunted in Germany. The most prevalent PFAS (PFOA, PFNA, PFHxS and PFOS) were detected in all analyzed samples. The median level of the sum (Σ 4PFAS) was highest in liver (90.2 μg/kg), followed by kidney (9.45 μg/kg), plasma (7.63 μg/L), lung (6.84 μg/kg), heart muscle (2.60 μg/kg), spleen (2.46 μg/kg), and skeletal muscle (1.03 μg/kg). Consumption of a single portion (125 g) of liver containing the Σ 4PFAS median level would result in a 36.6-fold exceedance of the tolerable weekly intake (TWI) of EFSA in a 70 kg-person. The accumulation (calculated as tissue/plasma ratio) of perfluoroalkyl carboxylic acids with ηpfc = 8-13 in lung, spleen, muscle and heart tissues increased with molecule size, indicating passive mechanisms of distribution driven by hydrophobicity. In contrast, liver and kidney distribution coefficients scattered, indicating additional involvement of chain-length dependent active transport processes. The highest accumulation was observed for PFOS in the liver (median tissue/plasma ratio 18.0). The shortest PFAS included in the study (PFHxA, PFHpA, PFOA, PFBS and PFHxS) did not accumulate in any of the tissues, probably due to strong binding to blood proteins like serum albumin and their relative polarity impeding passive membrane diffusion.

Respiratory Health Impacts from Natural Disasters and Other Extreme Weather Events: The Role of Environmental Stressors on Asthma and Allergies

PURPOSE OF REVIEW

The frequency of natural disasters, other extreme weather events, and downstream emissions of emerging contaminants is increasing. One category of health outcome that is now experiencing increased prevalence due to these environmental threats is respiratory disease, specifically asthma and allergies; though a review summarizing current knowledge and research gaps has not been synthesized on this topic in recent years despite growing evidence.

RECENT FINDINGS

We identified recent literature that connects allergy/asthma with environmental events that are increasing in prevalence alongside natural disasters and other extreme weather events, including algal blooms, floods, heat stress, wildfires, and thunderstorms. Coinciding emissions of per-and polyfluoroalkyl substances (PFAS) and microplastics (MPs) are also discussed as downstream outcomes of these environmental events. Available evidence ranged according to environmental event/stressor type, with over 50 papers identified as relevant to this research scope in the last five years. Narrative synthesis of these papers highlighted exposure-disease linkages for stressors related to natural disasters, other extreme weather events, and downstream emissions of emerging contaminants with pulmonary asthma and allergy outcomes. Underlying biological mechanisms are beginning to be elucidated and include widespread inflammation in the lungs and changes in immune cell signaling and function across the pulmonary system. Take home points in this review pave the way for future investigations to better understand the impacts of these environmental events amongst the complex milieu of threats becoming increasingly prevalent worldwide.

Hair analysis as a non-invasive method for assessing the exposure of wildlife to per- and poly-fluoroalkyl substances (PFAS)

In mammals, exposure to PFAS is usually assessed by measuring burdens in internal organs (i.e., liver and brain) or plasma, while less emphasis is devoted to non-invasive and non-destructive methods. We assess the suitability of hair as a non-invasive matrix for monitoring the exposure of mammals to 33 PFAS, including perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkane sulfonic acids (PFSAs), perfluoroalkylether carboxylic acids (PFECAs), perfluoroalkylether sulfonic acids (PFESAs), perfluoroalkane sulfonyl fluoride-based substances (PASFs), and fluorotelomers (FTs). The Red fox is chosen as the target species due to its apical position in the terrestrial food web of the study area, the Cavallino-Treporti peninsula in North-East Italy. All analysed samples (n = 24) are positive for PFAS, with eight compounds quantified in all samples, including PFHxA, PFOA, PFDA, PFUnDA, PFDoDA, PFTriDA, PFTeDA, and PFOS. The highest mean concentration in hair samples is measured for PFOS (1.40 ± 0.48 ng g-1 dw) followed by PFDoDA (0.31 ± 0.05 ng g-1 dw), and PFOA (0.31 ± 0.19 ng g-1 dw), while the mean ∑33PFAS was 3.41 ± 0.93 ng g-1 dw. The dominance of PFOS and long-chain PFAS in the PFAS profile and the occurrence of compounds with even-numbered carbon chains at higher concentrations than the odd-numbered compounds with a one-carbon longer chain (i.e., PFOA > PFNA, PFDA > PFUnDA, PFDoDA > PFTriDA) suggest the trophic transfer along the terrestrial food web as the primary exposure pathway in the study area. The data suggest hair analysis as a reliable, non-invasive method for assessing the possible exposure of mammals to PFAS and suggested that the Red fox can be used as a sentinel of the environment, embracing the One Health perspective.

Predicting aquatic toxicity of anionic hydrocarbon and perfluorinated surfactants using membrane-water partition coefficients from coarse-grained simulations

Anionic surfactants are widely used in commercial and industrial applications. For assessment of their environmental fate and effects, it is highly desirable to quantify the membrane-water partition/distribution coefficient (Kmw/Dmw). Here, we further develop a computational route to Dmw for anionic surfactants based on coarse-grained molecular dynamics simulations, validating it against new and existing experimental measurements. Having parameterised molecular fragments for the coarse-grained models, the simulations are used to predict Dmw for molecules where no experimental values are available. This expanded set of simulated Dmw values is then used to derive QSARs for acute toxicity of mono-constituent anionic surfactants in daphnids and fish, allowing for extrapolation to similar compounds without experimental Dmw values. For this study, we have selected hydrocarbon-based (HC) surfactants because of their widespread use, and perfluorinated (FC) surfactants as a challenging case study. Separate daphnid and fish QSARs demonstrate good fits, robustness and predictivity, and highlight differing toxicity relationships for HC and FC surfactants in daphnids. Overall, the combined use of simulated Dmw and derived QSARs is a promising approach for ecotoxicity screening of surfactants.

High-throughput screening of protein interactions with per- and polyfluoroalkyl substances (PFAS) used in photolithography

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals used extensively across industries, including semiconductor manufacturing. Semiconductors are ubiquitous, and there is increasing global demand for semiconductors, e.g., for advanced technologies and the automotive industry. Despite their extensive use, the toxicity and bioaccumulation potential of PFAS used in photolithography, a critical process in semiconductor manufacturing, remain poorly understood. Moreover, most lack experimental data and standards for testing. Here, we identified 96 photolithography-relevant PFAS and developed a computational framework to evaluate their potential hazards through protein binding. By integrating molecular dynamics (MD) and docking, we predicted the binding affinities and positions of PFAS to five proteins-liver fatty acid binding protein (LFABP), serum albumin (SA), peroxisome proliferator-activated receptors α and γ (PPARα and PPARγ), and transthyretin (TTR). These proteins were chosen as their binding with PFAS has been linked to PFAS bioaccumulation and to hepatic, reproductive, developmental, and endocrine disruption. Comparisons with empirical data demonstrated our approach balances simulation speed and robustness, better estimating absolute and relative binding affinities than docking alone. PFAS-protein binding affinities were generally positively associated with fluorinated chain length and the presence of aromatic rings, but limited by the protein binding pocket dimensions. Notably, we identified 22 PFAS with stronger predicted binding than perfluorooctane sulfonic acid (PFOS), a known hazardous PFAS, to at least one target protein, suggesting the potential for toxicological concern. By enabling proactive evaluation of PFAS that are unavailable for experimental testing, this work contributes to safeguarding environmental and human health amidst rising semiconductor demands.

Fatty Acid Metabolic Impairment in Soil Microbes Induced by PFAS: Dependence on the Fluorocarbon Chain Length, Headgroups, and Ether Attached

Per- and polyfluoroalkyl substances (PFASs) with varying chain lengths, headgroups, and alternative structures are widespread and persistent in soil, yet knowledge of their biological effects and toxic mechanisms on soil microorganisms is limited. This study identified the structure-dependent impacts of PFAS on microbial fatty acid (FA) profiles by integrated field-laboratory investigations. The field investigation uncovered distinct PFAS-FA interaction patterns, varying by PFAS fluorocarbon (FC) chain length and functional group, and FA hydrocarbon (HC) chain length and unsaturation degree. Specifically, long-chain perfluoroalkyl carboxylic acids (PFCAs, FC7-17) increased medium/long-chain FAs (HC ≤ 17) and monounsaturated FAs (MUFAs), while long-chain perfluoroalkyl sulfonic acids (PFSAs, FC6-8) enhanced longer-chain FAs (HC > 17) and MUFAs. Additionally, perfluoroether carboxylic acids (PFECAs) as well as short-chain PFCAs (FC < 7) and PFSAs (FC < 6), which commonly used as alternatives to long-chain PFCAs/PFSAs, were associated with polyunsaturated FAs (PUFAs). The laboratory investigation with Pseudomonas aeruginosa PAO1 validated these FA metabolic disruptions and revealed broader perturbations in phospholipids, acetyl-CoA, and secondary metabolite metabolisms, providing insights into dysregulated membrane synthesis, C/N metabolisms, and bacteria quorum sensing (QS) processes. These findings reveal novel structure-dependent effects of PFASs on microorganisms, highlighting microbial FA profiles as potential metabolic biomarkers for assessing PFAS toxicity and soil health.

Assessing Bivalves as Biomonitors of Per- and Polyfluoroalkyl Substances in Coastal Environments

Per- and polyfluoroalkyl substances (PFAS) are widely used chemicals that enter coastal ecosystems through various pathways. Despite the ecological and economic significance of coastal environments, monitoring efforts to identify PFAS in these regions are limited. Bivalves have been used as biomonitors for many pollutants, but their effectiveness in reflecting environmental PFAS contamination and the mechanisms of PFAS bioaccumulation is poorly understood. This study examined the impact of biological, chemical, and ecological variables on PFAS bioaccumulation in two bivalve species (i.e., Eastern oyster and Atlantic ribbed mussel) and developed a statistical model to predict the PFAS content in wild bivalves. Overall, the summed PFAS concentration in the bivalves closely mirrors that in water. We observed higher bioaccumulation factors for some perfluoroalkyl sulfonamides and branched PFAS isomers than for terminal PFAS of equivalent chain length. The isomer distribution and precursor-to-terminal compound ratios provide compelling evidence that the biotransformation of PFAS precursors likely drives these elevated factors. Additionally, the bioaccumulation factors of PFAS decrease with increasing organism size and age, suggesting that smaller and younger bivalves have greater bioaccumulation potential and are more susceptible to PFAS contamination. These findings provide critical information that guides the use of bivalves as biomonitors to evaluate PFAS contamination in aquatic environments.

6:2 Fluorotelomer Ethoxylates in Human Serum and Residential Homes: A Growing Environmental Health Concern

As an emerging group of per- and polyfluoroalkyl substances (PFAS), fluorotelomer ethoxylates (FTEOs) are widely employed as a major ingredient in antifog products. However, knowledge about their environmental distribution and human exposure remains scarce. Herein, we reported the ubiquitous detection of 6:2 FTEO homologues in popular antifog products (n = 47), indoor dust from residential homes (n = 80), and serum of pregnant women (n = 90) living in South China, demonstrating broad use and widespread human exposure. The cumulative concentrations of 6:2 FTEOs ranged from below the limit of detection ( Collapse

Key Words

• 6:2 fluorotelomer ethoxylates
• antifog products
• house dust
• human serum
• molecular docking
• per- and polyfluoroalkyl substances

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MESH Headings

• Female
• Humans
• China
• Dust/analysis
• Environmental Exposure
• Environmental Health
• Fluorocarbons
• Housing
• Surface-Active Agents/analysis
• Environmental Pollutants/analysis
• Environmental Pollutants/blood

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Grants Collapse

Affiliation(s)

Yao Cheng College of Life Science and Technology, Jinan University, Guangzhou 510632, China College of Environment and Climate, Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou 510632, China
Yan Wang College of Life Science and Technology, Jinan University, Guangzhou 510632, China
Xiaodong Wang College of Life Science and Technology, Jinan University, Guangzhou 510632, China
Zhong Lv Shenzhen Key Laboratory of Precision Measurement and Early Warning Technology for Urban Environmental Health Risks, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
Fengli Zhou College of Life Science and Technology, Jinan University, Guangzhou 510632, China College of Environment and Climate, Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou 510632, China
Baoqin Huang Department of Obstetrics, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou 510630, China
Xiaotu Liu College of Environment and Climate, Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou 510632, China
Da Chen College of Environment and Climate, Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou 510632, China

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Collaborators Collapse

Accumulation of lipophilic and proteinophilic halogenated organic pollutants (HOPs) in the different types of feathers of laying hens

This study investigated the bioaccumulation of halogenated organic pollutants (HOPs) in three types of feathers from laying hens through exposure experiments. The HOPs included lipophilic polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), as well as proteinophilic perfluoroalkyl carboxylic acids (PFCAs). Concentrations of PCBs, PBDEs, and short-chain PFCAs (≤8) were significantly higher in the body feathers than in the primary feathers, while long-chain PFCAs (>8) showed no significant differences among primary, tail, and body feathers. The concentration order in the feathers was ∑12PFCAs > ∑7PBDEs > ∑13PCBs, which was completely reversed by the exposure dose. The transfer rates (TRs) (concentration ratio of feather to serum) of PFCAs (0.11-6.8) were one order of magnitude higher than those (0.01-0.30) of PCBs and PBDEs. These results indicate that PFCAs preferentially accumulate in feathers compared to PBDEs and PCBs. TRs, regardless of whether they were lipophilic or proteinophilic HOPs, were significantly and positively correlated with the protein-water partition coefficient (log Kpw). Strong and significant correlations between feathers and inner tissues were primarily observed in body feathers. Egg-laying significantly affects PFCA accumulation in feathers and even distorts the actual exposure dose in hens; however, its impact on PCBs and PBDEs is limited. These findings provide crucial insights into HOP deposition in bird feathers.

Number of Carbons Is a Critical Parameter for Accumulation of Per- and Polyfluoroalkyl Substances in the Human Brain

Per- and polyfluoroalkyl substances (PFAS), a large group of manmade chemicals, have been detected extensively in the blood of people living in developed countries. Although it has been suggested that PFAS exposure might be associated with harmful effects on the brain, few studies have assessed the presence of PFAS in brain tissues. This study aimed to evaluate the concentrations of a broad range of PFAS in paired postmortem human brain and serum samples and investigate brain-to-serum concentration ratios. A partitioning experiment using PFAS-fortified animal brain samples additionally investigated differences in distribution between lipid-rich brain and water for different PFAS. Out of the 43 PFAS analyzed, 5 were detected in all paired human brain and serum samples, 11 were found in all serum, and 7 were found in all brain samples. Two PFAS compounds were observed at notably higher detection frequencies in brain samples compared to serum. The brain-to-serum ratios of PFAS concentrations ranged from approximately 0.04 for perfluorohexanesulfonate (PFHxS) to 1.3 for N-methyl perfluorooctanesulfonamido acetic acid (N-MeFOSAA) with a clear increase in PFAS brain-to-serum ratios with the total number of carbons. There were no differences between the two cortical brain regions analyzed. Results underscore the necessity of a better understanding of individual PFAS, as the difference in their properties can influence their behavior within the human brain.

Modelling PFAS transport in Lake Ekoln: Implications for drinking water safety in the stockholm region

Per- and polyfluoroalkyl substances (PFAS) are found frequently in both groundwater and surface water sources across Sweden posing challenges to drinking water supply. Lake Ekoln is located south of Uppsala and is the basin of Lake Mälaren; Lake Mälaren is the third largest lake in Sweden and is the drinking water source for more than two million people. The aim of this study was to simulate the fate and transport of PFAS in Lake Ekoln during the period 2017-2020 using three-dimensional hydrodynamic modelling. The simulated water temperatures were in agreement with the observed water temperatures. The simulated PFAS concentrations were generally in agreement with the available measurements, but the lack of measurements made the comparison uncertain. The modelling results described the seasonal variations of PFAS in Lake Ekoln informing the operation of the drinking water treatment plants located downstream. The modelling results confirmed that the main inflow to the lake - the river Fyrisån - is the main source of PFAS to Lake Ekoln, highlighting the importance of mitigating this source in the context of ensuring safe drinking water supply in the Stockholm region. Regular monitoring of PFAS in the river Fyrisån is needed, and additional measurements in Lake Ekoln would facilitate further model development.

Spatial variations in per- and polyfluoroalkyl substance concentrations in pooled sera from inland, coastal, and island populations

Per- and polyfluoroalkyl substances (PFAS) are a class of ubiquitously detected chemicals, some of which are highly persistent and bioaccumulative in humans. Within the general population, dietary ingestion is considered a primary pathway for PFAS exposure, and seafood consumption specifically has been associated with higher serum PFAS concentrations. Proximity of residence to the ocean may influence dietary habits, particularly seafood consumption, and exposure to geographically specific PFAS sources such as sea spray aerosols (SSA). The objective of this study was to evaluate potential spatial trends in serum PFAS concentrations between Australian coastal and island populations compared to those with inland residency. Human sera were obtained from deidentified surplus pathology samples and pooled with respect to geographical location, sex (male or female), and age group (males: ≥15-<45 years, ≥45 years; females: ≥15-<45 years, ≥45-<60 years, ≥60 years) stratification criteria. Serum samples were then analysed for PFAS using High Performance Liquid Chromatography-Mass Spectrometry (HP LC-MS). A total of 13 of the 45 targeted PFAS were quantifiable in at least one pooled sample, including the detection of perfluorooctane sulfonate (PFOS) replacement compounds 5:3 fluorotelomer carboxylic acid (5:3 FTCA) and potassium 9-chlorohexadecafluoro-3-oxanonane-1-sulfonate (9Cl-F53B). Significant spatial trends were observed in males aged ≥45 years, with serum concentrations of PFOS, perfluorobutanoic acid (PFBA), perfluorodecanoic acid (PFDA) and perfluoroheptane sulfonic acid (PFHpS) demonstrated to be 32-77% higher in pooled samples from island locations compared with inland. A similar trend was observed for PFHpS in coastal locations. Whilst deidentification of samples limited inferences about exposure pathways associated with the observed trends, this study indicated the feasibility of utilising pooled samples for assessing spatial variations in serum PFAS concentrations between geographically distinct subpopulations.

Assessing perfluoroalkyl substance pollution in Central Mediterranean breeding shearwaters

Per- and polyfluoroalkyl substances (PFAS) are synthetic organofluorine compounds used in various products, which are highly durable in the environment and may pose risks to wildlife health. We investigated the blood cell concentrations of PFAS in breeding Scopoli's shearwaters (Calonectris diomedea) from three different colonies in the central and southern Mediterranean (Linosa, Malta, and La Maddalena). Shearwaters are flexible, high trophic level foragers, and foraging areas may differ according to sex and breeding stage. We examined inter- and intracolony differences in PFAS blood concentrations and compared them with exploited foraging areas and dietary tracers. Per- and polyfluoroalkyl substances were detected in all samples, with the major congeners detected in descending order being perfluoroctanesulfonic acid (PFOS), perfluoroundecanoic acid (PFuNA), perfluorododecanoic acid (PFDoDA), and perfluorotridecanoic acid (PFTriDA). The mean sum of PFAS during the chick-rearing phase was highest in the birds from Malta (145.1 ng/g dry wt, 95% confidence interval [CI] of the mean 106.8, 183.5) compared with Linosa (91.5 ng/g dry wt, 95% CI 72.9, 110.1) and La Maddalena (84.5 ng/g dry wt, 95% CI 61.7, 107.3), and the PFAS blood composition of shearwaters from La Maddalena and Malta differed. The PFAS concentrations in shearwaters from Linosa were higher during incubation than during chick-rearing, and males had higher PFAS concentrations than females during incubation. Some PFAS were associated with carbon and nitrogen stable isotope values. After baseline adjustment of stable isotope values, no differences were observed for adjusted δ15N and δ13C between the three colonies, suggesting that differences in PFAS levels attributed to diet were minor compared with regional differences. Our study highlights that shearwaters are useful biomonitors of PFAS exposure in remote marine areas.

Distinct binding affinity of perfluoroalkyl acids to plant and animal proteins revealed by dialysis experiments, fluorescence spectroscopy, and QSAR modeling

Understanding the binding dynamics between perfluoroalkyl acids (PFAAs) and proteins is crucial for risk assessment, as protein binding plays a vital role in the bioaccumulation of PFAAs. This study employed dialysis experiments to measure the protein-water partition coefficient of PFAAs with representative plant and animal proteins, including standard bovine serum albumin, soy protein isolate, and C-phycocyanin. Fluorescence spectroscopy was investigated to elucidate the binding affinity of PFAAs on bovine serum albumin (BSA). Additionally, through the construction of the quantitative structure-activity relationship (QSAR) model, this research comprehensively analyzed the binding characteristics of various PFAAs to proteins, offering insights into the molecular mechanisms of PFAAs-protein interactions. The results revealed that the binding capacity of bovine serum albumin for PFAAs was significantly superior to that of C-phycocyanin and soy protein isolate. Electrostatic attraction was the predominant factor influencing the interaction between proteins and PFAAs. The binding of PFAAs to proteins was chiefly mediated by tryptophan residues, and there was no notable change in the protein conformation pre- and post-binding. Finally, the QSAR models, constructed with energy gap (Egap) between the highest occupied and the lowest unoccupied molecular orbitals, the net charge of the most negative atom (q), and ionic volume as descriptors, suggested that the hydrophobic interactions, electrostatic interactions, and the stability of PFAA molecule are key factors affecting PFAA-protein binding. This study enhances our comprehension of the binding capacity of animal and plant proteins to PFAAs, while also establishing a foundation for future research on the binding of emerging PFAA alternatives to proteins.

Deriving Membrane-Water and Protein-Water Partition Coefficients from In Vitro Experiments for Per- and Polyfluoroalkyl Substances (PFAS)

The phospholipid membrane-water partition coefficients (KMW) and equilibrium binding affinities for human serum albumin (HSA) of 60 structurally diverse perfluoroalkyl and polyfluoroalkyl substances (PFAS) were evaluated through laboratory measurements and modeling to enhance our understanding of PFAS distribution in organisms. Per- and polyfluoroalkyl carboxylic acids exhibited a 0.36 ± 0.01 log-unit increase in KMW as the fluorinated carbon chain length increased from C4 to C16, while per- and polyfluoroalkyl sulfonates showed a 0.37 ± 0.02 log-unit increase. The highest HSA affinity range was observed between C6 and C10, with the following structural subclass order: per- and polyfluoroalkyl sulfonates ≈ ether sulfonic acids > polyfluoroalkyl carboxylic acids > fluorotelomer unsaturated carboxylic acids > phosphate diesters ≈ per- and polyfluoroether carboxylic acids. A comparison between association rate constants (KA) and HSA-PFAS molecular docking predictions with AutoDock Vina indicated that modeling could effectively predict the affinity of PFAS to HSA, especially for PFAS carbon chain lengths from C4 to C10. Based on in vitro results, exposure-dependent PFAS partitioning in organisms was modeled by comparing distribution coefficients between PFAS in phospholipid membranes and HSA at different PFAS concentrations and demonstrated that at lower concentrations, PFAS had higher partitioning in HSA, while with increasing concentration, the proportion of binding relative to the aqueous phase shifted toward the phospholipid membrane. Few studies have compared the bioaccumulation of PFAS in phospholipid membranes and HSA. This research reports that protein-water distribution coefficients are higher than membrane-water partitioning coefficients at lower PFAS concentrations, which may have implications for interpreting exposure data and toxicity experiments.

Nanomolar PFOA Concentrations Affect Lipid Membrane Structure: Consequences for Bioconcentration Mechanisms

Independent methods show that sub-microMolar concentrations of perfluorooctanoic acid (PFOA), a member of the PFAS family of "forever chemicals", change the properties of DPPC vesicle bilayers. Specifically, calorimetry measurements show that PFOA at concentrations as low as 0.1 nM lowers DPPC's gel-liquid crystalline transition enthalpy by several J/g without changing the transition temperature (Tgel-LC), and dynamic light scattering (DLS) data illustrate that PFOA markedly broadens the size distribution of DPPC vesicles. Furthermore, DLS results from PFOA-containing, DPPC vesicle solutions also contain smaller objects having diameters of 30-50 nm. Close inspection of cryo-EM images reveals that DPPC vesicles formed in the presence of PFOA are multilamellar and the smaller objects have a clear bilayer structure similar to niosomes. A consequence of these PFOA-induced changes to DPPC bilayer structure is that the bilayers themselves are more susceptible to secondary solute accumulation. Time resolved emission measurements of Coumarin 152 (C152) report that C152 is 3-fold more likely to partition into the bilayer's acyl chain, hydrophobic interior when PFOA is present, and fluorescence lifetimes from C152 partitioned into the polar region of the lipid bilayer show evidence of PFOA-induced membrane hydration below Tgel-LC.

Cleaner cuts: Farmed fish and skin-off fillets are lower in per- and polyfluoroalkyl substances (PFAS)

The ubiquitous occurrence and persistence of per- and polyfluoroalkyl substances (PFAS) in all environmental matrices and biota poses significant health risks to humans. Fish consumption is one of the main pathways humans are exposed to PFAS, yet general patterns in factors influencing PFAS content in fish fillets remain unknown. We assembled information on PFAS content (total quantified PFAS, PFOS, PFOA, and others) in fish fillets to assess the effect of fish origin (marine, freshwater, wild, or farmed), fillet type (skin-on or skin-off), and lipid content on PFAS variation across environments at a global scale. We found that these factors influenced PFAS contents in fish fillets, with concentrations reaching up to 2149 ng•g wet mass-1 (WM). Specifically, PFOS and PFOA in skin-off fillets were consistently lower in farmed than wild fish across freshwater and marine environments. In freshwater wild fish, PFOS was lower in skin-off fillets than skin-on fillets at group and species levels, and multiple PFAS showed an inverse relationship with the lipid content of skin-off fillets, though the slopes showed varying steepness depending on the carbon chain length and functional group of the PFAS. However, the high variability of PFAS content across sites in aquatic environments and the complexity of PFAS bioaccumulation mechanisms in fish tissues may lead to variable results at a fine scale (i.e., species level); this highlights general patterns of factors influencing PFAS bioaccumulation that may inform the management of human exposure to PFAS through dietary consumption.

Exposure to specific polyfluoroalkyl chemicals is associated with cardiovascular disease in US adults: a population-based study

Background

Polyfluoroalkyl chemicals (PFCs) present potential health risks due to their persistence and bioaccumulation. However, there is currently insufficient evidence regarding their impact on cardiovascular disease (CVD). Consequently, it is imperative to investigate the correlation between PFCs and CVD.

Methods

The data was collected from National Health and Nutrition Examination Survey in 2005-2012. Logistic regression models were employed to assess the association between single PFC and CVD. Generalized additive model (GAM) was used for evaluating nonlinear relationships. Subgroup analyses were conducted to explore interaction effects. Bayesian kernel machine regression (BKMR) and weighted quantile sum (WQS) models were used to evaluate the joint effect of PFC exposures on CVD.

Results

In logistic regression, PFDE, MPAH, and PFUA were positively associated with CVD. In the GAM, there was a significant nonlinear relationship between MPAH and CVD. Subgroup analysis revealed the interaction of gender and race in the effects of PFCs and CVD. PFUA was positively correlated with CVD in males but show no significant difference in females. PFDE was positively associated with CVD among non-Hispanic white individual. The results of BKMR indicated that the impact of mixed PFCs on CVD increased initially and then weakened, showing an overall positive trend. The results of WQS suggested that PFDO contributed most to the effect.

Conclusion

Our study showed that serum PFDE, MPAH, and PFUA levels were positively correlated with CVD. PUFA was found to interact with gender and race in relation to CVD. A general positive correlation exists between mixed exposure to PFCs and CVD, with PFDO being the most contributory PFC. Our study provided important evidence for probing the impact of PFCs on CVD and laid a foundation for further mechanism research.

An in vitro and machine learning framework for quantifying serum albumin binding of per- and polyfluoroalkyl substances

Per- and polyfluoroalkyl substances (PFAS) are a diverse class of anthropogenic chemicals; many are persistent, bioaccumulative, and mobile in the environment. Worldwide, PFAS bioaccumulation causes serious adverse health impacts, yet the physiochemical determinants of bioaccumulation and toxicity for most PFAS are not well understood, largely due to experimental data deficiencies. As most PFAS are proteinophilic, protein binding is a critical parameter for predicting PFAS bioaccumulation and toxicity. Among these proteins, human serum albumin (HSA) is the predominant blood transport protein for many PFAS. We previously demonstrated the utility of an in vitro differential scanning fluorimetry assay for determining relative HSA binding affinities for 24 PFAS. Here, we report HSA affinities for 65 structurally diverse PFAS from 20 chemical classes. We leverage these experimental data, and chemical/molecular descriptors of PFAS, to build 7 machine learning classifier algorithms and 9 regression algorithms, and evaluate their performance to identify the best predictive binding models. Evaluation of model accuracy revealed that the top-performing classifier model, logistic regression, had an AUROC (area under the receiver operating characteristic curve) statistic of 0.936. The top-performing regression model, support vector regression, had an R2 of 0.854. These top-performing models were then used to predict HSA-PFAS binding for chemicals in the EPAPFASINV list of 430 PFAS. These developed in vitro and in silico methodologies represent a high-throughput framework for predicting protein-PFAS binding based on empirical data, and generate directly comparable binding data of potential use in predictive modeling of PFAS bioaccumulation and other toxicokinetic endpoints.

Bioconcentration, maternal transfer, and toxicokinetics of PFOS in a multi-generational zebrafish exposure

To enable risk characterization of perfluorooctane sulfonic acid (PFOS) in extended chronic and multi-generational exposures, we assessed PFOS bioconcentration in zebrafish (Danio rerio) exposed continuously to environmentally-relevant PFOS concentrations (0, 0.1, 0.6, 3.2, 20, and 100 µg/L PFOS) through 180 days postfertilization (dpf) in parental (P) and first filial generation (F1) fish. Exposures included five replicate tanks per treatment where whole-body PFOS concentrations were measured using 20-35 fish per replicate at 14 and 29 dpf in the P generation and one fish of each sex per replicate at 180 dpf for the P and F1 generations. Perfluorooctane sulfonic acid accumulation reached an apparent steady state at ≤ 14 dpf where whole-body wet-weight concentrations remained constant through 180 dpf in the P and F1 generations. The median bioconcentration factor (BCF) of 934 L/kg was observed for all PFOS exposures with a range from 255 to 2,136 L/kg which varied with PFOS exposure concentration and sex of adult fish. Significantly lower BCFs were observed in 20 and 100 µg/L PFOS exposures versus 0.1 and 0.6 µg/L indicating exposure-concentration dependance. Additionally, males had significantly increased (∼2×) PFOS accumulation and BCFs versus females in both P and F1 generations. Maternal transfer of PFOS was observed from P females to F1 eggs where maternal whole-body and egg PFOS burdens were equivalent, suggesting PFOS transfer to eggs was not a depuration pathway. Finally, a toxicokinetic model was developed that reliably reproduced PFOS whole-body burdens (data within 1.64-fold of predicted values) across all exposure durations spanning the P and F1 generations, providing a tool for PFOS bioaccumulation predictions relevant for risk assessment of acute, chronic, and multi-generational exposures.

Serum metabolome associated with novel and legacy per- and polyfluoroalkyl substances exposure and thyroid cancer risk: A multi-module integrated analysis based on machine learning

BACKGROUND

Exposure to per- and polyfluoroalkyl substances (PFAS) may linked to thyroid cancer (TC) risk, but inconsistent findings and a lack of studies on mixed exposures exist, especially regarding novel PFAS compounds. Additionally, little is known about the potential mechanisms underlying the association.

OBJECTIVES

Explore the effects of PFAS exposure on the serum metabolome and its correlation with TC.

METHODS

A 1:1 age- and sex-matched case-control study was administered with 746 TC cases and healthy controls. Liquid chromatography-high resolution mass spectrometry determined serum 11 PFAS and untargeted metabolome profile. ENET and LightGBM models were used to explore the exposure patterns and perform variable selection. The mixed exposure effects were assessed using Weighted quantile sum regression and Bayesian kernel machine regression. Metabolome-wide association analyses were performed to assess metabolic dysregulation associated with PFAS, and a structural synthesis analysis was used to detect latent groups of individuals with TC based on PFAS levels and metabolite patterns.

RESULTS

Ten of the 11 PFAS were detected in > 80 % of the population. PFHxA and PFDoA exposure associated with increased TC risk, while PFHxS and PFOA associated with decreased TC risk in single compound models (all P < 0.05). Machine learning algorithms identified PFHxA, PFDoA, PFHxS, PFOA, and PFHpA as the key PFAS influencing the development of TC, and mixed exposures have an overall positive effect on TC risk, with PFHxA making the primary contribution. A novel integrative analysis identified a cluster of TC patients characterized by increased PFHxA, PFDoA, PFHpA and decreased PFOA, PFHxS levels, and altered metabolite patterns highlighted by the upregulation of free fatty acids.

CONCLUSIONS

PFAS exposure is linked to a higher risk of TC, possibly through changes in fatty acid metabolism. Larger, prospective studies are needed to confirm these findings, and the role of short-chain PFAS requires more attention.

Investigating the Mechanism of Neurotoxic Effects of PFAS in Differentiated Neuronal Cells through Transcriptomics and Lipidomics Analysis

Per- and polyfluorinated alkyl substances (PFAS) are pervasive environmental contaminants that bioaccumulate in tissues and pose risks to human health. Increasing evidence links PFAS to neurodegenerative and behavioral disorders, yet the underlying mechanisms of their effects on neuronal function remain largely unexplored. In this study, we utilized SH-SY5Y neuroblastoma cells, differentiated into neuronal-like cells, to investigate the impact of six PFAS compounds─perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorodecanoic acid (PFDA), perfluorodecanesulfonic acid (PFDS), 8:2 fluorotelomer sulfonate (8:2 FTS), and 8:2 fluorotelomer alcohol (8:2 FTOH)─on neuronal health. Following a 30 μM exposure for 24 h, PFAS accumulation ranged from 40-6500 ng/mg of protein. Transcriptomic analysis revealed 721 differentially expressed genes (DEGs) across treatments (padj < 0.05), with 11 DEGs shared among all PFAS exposures, indicating potential biomarkers for neuronal PFAS toxicity. PFOA-treated cells showed downregulation of genes involved in synaptic growth and neural function, while PFOS, PFDS, 8:2 FTS, and 8:2 FTOH exposures resulted in the upregulation of genes related to hypoxia response and amino acid metabolism. Lipidomic profiling further demonstrated significant increases in fatty acid levels with PFDA, PFDS, and 8:2 FTS and depletion of triacylglycerols with 8:2 FTOH treatments. These findings suggest that the neurotoxic effects of PFAS are structurally dependent, offering insights into the molecular processes that may drive PFAS-induced neuronal dysfunction.

Persistent organic pollutants exposure and risk of depression: A systematic review and meta-analysis

Recently, more and more epidemiological studies have examined the impact of exposure to persistent organic pollutants (POPs) on depression, but the results are inconsistent. Thus, we conducted a systematic review and meta-analysis to better understand the effects of POPs exposure on the risk of depression in the general population. We searched PubMed, Embase, Web of Science, and Scopus databases for studies before March 20, 2024. Random-effects meta-analysis was applied to calculate pooled relative risk (OR) and 95% confidence intervals (CIs). We also assessed potential heterogeneity and publication bias across studies and conducted sensitivity analysis. A total of 26 studies were included, and the results indicated that exposure to ΣPBDEs, PBDE-47, and PBDE-99 increased the risk of depression, with OR of 1.37 (95 % CI = 1.06-1.79), 1.30 (95% CI = 1.08-1.56), 1.46 (95 % CI = 1.00-2.12) respectively. On the contrary, the exposure assessment results of PFOS showed a negative correlation with the risk of depression. There is no association between exposure to ΣPFAS, ΣPCBs, and ΣOCPs and increased risk of depression. More standardized studies and more samples are needed in the future to confirm the findings of this study. This finding could provide theoretical references for the prevention and management of depression and offer insights for the risk assessment of POPs exposure.

Microplastic and associated emerging contaminants in marine fish from the South China Sea: Exposure and human risks

Microplastics can act as vectors of chemical contaminants in aquatic environments, but the extent to which this phenomenon contributes to chemical exposure in marine organisms remains poorly understood. We investigated the occurrence of microplastics and emerging contaminants (ECs), including antibiotics and per- and polyfluoroalkyl substances (PFAS) in 14 marine fish species. Microplastics were detected in all marine fish species, mainly in the gastrointestinal tract. Fluoroquinolones and tetracyclines were the dominant antibiotics in fish muscles with maximum concentrations of 24.84 and 26.95 ng g-1 ww, while perfluorooctanesulfonic acid (PFOS, 0.039-0.95 ng g-1 ww) was the dominant component in the PFAS profile. Fish with more microplastics had significantly higher concentrations of fluoroquinolones and perfluoroalkyl acids than fish with less microplastics (p < 0.05), but the correlation was not observed in other chemicals. Structural equation modeling revealed the contribution of microplastics in fish on the level of ECs contamination. The health quotient value indicated the low health risk of single compounds via fish consumption to humans; however, the combined risk of microplastics and ECs still needs to be considered. This work highlights the link between microplastics with associated ECs ingested by aquatic organisms and the human health risk of consuming polluted seafood.

Tissue distribution of emerging per- and polyfluoroalkyl substances in wild fish species from Qiantang river, east China: Comparison of 6:2 Cl-PFESA with PFOS

This study argued for the first time that 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) and perfluorooctanesulfonic acid (PFOS) might have different tissue distribution mechanisms in wild fish species. Nine emerging and legacy per- and polyfluoroalkyl substances (PFASs) were detected in the water and wild fish tissues samples collected from the Qiantang River. Perfluorooctanoic acid (213 ng/L) was the predominant PFAS contaminant, and the other contaminants included perfluorohexanoate (19 ng/L), perfluorobutanoate (199 ng/L) and hexafuoropropylene oxide dimer acid (55 ng/L), which are the main fluorinated alternatives used in various industries located along the Qiantang River. Furthermore, PFOS (742 ng/g) and 6:2 Cl-PFESA (9.0 ng/g) were the predominant PFAS contaminants detected in the fish tissue samples. The differences in the potential molecular mechanism of the tissue distribution of PFOS and 6:2 Cl-PFESA in wild fish species are discussed. Additionally, we hypothesize that phospholipid partitioning is the primary mechanism underlying the tissue distribution of PFOS, and that a specific protein-binding mechanism is involved in the tissue distribution of 6:2 Cl-PFESA.

Per- and polyfluoroalkyl substances (PFAS): Trends in mass spectrometric analysis for human biomonitoring and exposure patterns from recent global cohort studies

Per- and polyfluoroalkyl substances (PFAS) are widespread environmental contaminants that have been shown to contribute to human exposure, thereby raising a range of health concerns. In this context, human biomonitoring is essential for linking exposure levels of PFAS with their potential health risks. Mass spectrometry-based analytical techniques have been extensively adopted for the evaluation of PFAS levels across various cohorts. However, challenges arising from the use of biological samples (e.g., plasma, serum, urine, etc.) necessitate ongoing research and refinement of analytical methodologies. This review provides an overview of current trends in mass spectrometry-based approaches for human biomonitoring of PFAS, including sample collection and preparation, and instrumental techniques. We also explore analytical strategies to overcome challenges in obtaining PFAS-free blank matrices and address the risk of background contamination. Moreover, this review examines differing PFAS exposure patterns across regions by analyzing recent international cohort studies, specifically those conducted in the US and China over the past five years. Accordingly, several key research gaps in biomonitoring studies that need to be addressed moving forward are highlighted.

Insights into the neurotoxicity and oxidative stress to the freshwater amphipod Hyalella azteca induced by hexafluoropropylene oxide trimer acid

With the regulation and phase-out of conventional per- and polyfluoroalkyl substances (PFAS), there is a growing trend towards seeking alternatives that are less toxic and less persistent. Hexafluoropropylene oxide trimer acid (HFPO-TA) is one of the alternatives to perfluorooctanoic acid (PFOA), the latter being widely present in the environment globally. However, there is limited information regarding the biological toxicity of HFPO-TA to aquatic organisms. In this study, the freshwater benthic amphipod, Hyalella azteca, was used to assess the acute and chronic toxicity of HFPO-TA in both water and sediment. HFPO-TA was found to be more toxic to H. azteca than PFOA, as indicated by greater production of reactive oxygen species (p < 0.05) and increasing catalase activity (p < 0.05). In addition, exposure to HFPO-TA affected the swimming behavior and the acetylcholinesterase (AChE) activity of the amphipod. Molecular docking models revealed that HFPO-TA can bind to AChE with a stronger binding affinity than PFOA. Furthermore, an integrated biomarker response index indicated that environmentally relevant concentration (1-100 μg/L) of HFPO-TA may cause toxicity to H. azteca, encompassing oxidative stress and neurotoxicity. This study provides new insights into the toxicity mechanisms of HFPO-TA and is valuable for assessing the ecological safety of this compound.

A proof-of-concept multi-tiered Bayesian approach for the integration of physiochemical properties and toxicokinetic time-course data for Daphnia magna

The use of in silico and in vitro methods, commonly referred to as New Approach Methodologies (NAMs), has been proposed to support environmental (and human) chemical safety decisions, ensuring enhanced environmental protection. Toxicokinetic models developed for environmentally relevant species are fundamental to the deployment of a NAMs-based safety strategy, enabling the conversion between external and internal chemical concentrations, although they require historical toxicokinetic data and robust physical models to be considered a viable solution. Daphnia magna is a key model organism in ecotoxicology albeit with limited and scattered quantitative toxicokinetic data, as for most invertebrates, resulting in a lack of robust toxicokinetic models. Moreover, current D. magna models are chemical specific, which restricts their applicability domain. One aim of this study was to address the current data availability limitations by collecting toxicokinetic time-course data for D. magna covering a broad chemical space and assessing the dataset's uniqueness. The collated toxicokinetic dataset included 48 time-courses for 30 chemicals from 17 studies, which was developed into an R package named AquaTK, with 11 studies unique to our work when compared to existing databases. Subsequently, a proof-of-concept Bayesian analysis was developed to estimate the steady-state concentration ratio (internal concentration / external concentration) from the data at three different levels of precision given three different data availability scenarios for environmental risk assessment. Specifically, an atrazine case study illustrates the multi-level modelling approach providing improvements (uncertainty reductions) in predictions of ratios for increasing amounts of data availability. Our work provides a consistent and self-contained Bayesian framework that irrespective of the hierarchy or resolution of individual experiments, can utilise the available information to generate optimal predictions of steady-state concentration ratios in D. magna. This approach is paramount to supporting the implementation of a NAMs based environmental safety paradigm shift in environmental risk assessment.

A Comparative Biodegradation Study to Assess the Ultimate Fate of Novel Highly Functionalized Hydrofluoroether Alcohols in Wastewater Treatment Plant Microcosms and Surface Waters

Per- and polyfluoroalkyl substances (PFAS) are a class of chemicals present in a wide range of commercial and consumer products due to their water-repellency, nonstick, or surfactant properties, resulting from their chemical and thermal stability. This stability, however, often leads to persistence in the environment when they are inevitability released. We utilized microbial microcosms from wastewater treatment plant (WWTP) sludge to determine how employing different functional groups such as heteroatom linkages, varying chain lengths, and hydrofluoroethers (HFEs) will impact the ultimate fate of these novel PFAS structures. A suite of five novel fluorosurfactant building blocks (F7C3OCHFCF2SCH2CH2OH (FESOH), F3COCHFCF2SCH2CH2OH (MeFESOH), F7C3OCHFCF2OCH2CH2OH (ProFdiEOH), F7C3OCHFCF2CH2OH (ProFEOH), and F3COCHFCF2OCH2CH2OH (MeFdiEOH)) and their select transformation products, were incubated in WWTP aerobic microcosms to determine structure-activity relationships. The HFE alcohol congeners with a thioether (FESOH and MeFESOH) were observed to transform faster than the ether congeners, while also producing second-generation HFE acid products (F7C3OCHFC(O)OH (2H-3:2 polyfluoroalkyl ether carboxylic acid [PFECA]) and F3COCHFC(O)OH (2H-1:2 PFECA). Subsequent biodegradation experiments with 2H-1:2 PFESA and 2H-1:2 PFECA displayed no further transformation over 74 days. Surface water Photofate experiments compared 2H-1:2 PFECA, and 2H-1:2 polyfluorinated ether sulfonate (PFESA) with their fully fluorinated ether acid counterparts, and demonstrated the potential for both HFE acid species to completely mineralize over extended periods of time, a fate that highlights the value of studying novel PFAS functionalization. Environ Toxicol Chem 2024;43:2297-2305. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Characterizing the Areal Extent of PFAS Contamination in Fish Species Downgradient of AFFF Source Zones

Most monitoring programs next to large per- and polyfluoroalkyl substances (PFAS) sources focus on drinking water contamination near source zones. However, less is understood about how these sources affect downgradient hydrological systems and food webs. Here, we report paired PFAS measurements in water, sediment, and aquatic biota along a hydrological gradient away from source zones contaminated by the use of legacy aqueous film-forming foam (AFFF) manufactured using electrochemical fluorination. Clustering analysis indicates that the PFAS composition characteristic of AFFF is detectable in water and fishes >8 km from the source. Concentrations of 38 targeted PFAS and extractable organofluorine (EOF) decreased in fishes downgradient of the AFFF-contaminated source zones. However, PFAS concentrations remained above consumption limits at all locations within the affected watershed. Perfluoroalkyl sulfonamide precursors accounted for approximately half of targeted PFAS in fish tissues, which explain >90% of EOF across all sampling locations. Suspect screening analyses revealed the presence of a polyfluoroketone pharmaceutical in fish species, and a fluorinated agrochemical in water that likely does not accumulate in biological tissues, suggesting the presence of diffuse sources such as septic system and agrochemical inputs throughout the watershed in addition to AFFF contamination. Based on these results, monitoring programs that consider all hydrologically connected regions within watersheds affected by large PFAS sources would help ensure public health protection.

Development and Evaluation of Aquatic and Terrestrial Food Web Bioaccumulation Models for Per- and Polyfluoroalkyl Substances

There is a need for reliable models to predict the food web bioaccumulation and assess ecological and human health risks of per- and polyfluoroalkyl substances (PFAS). This present study presents (i) the development of novel mechanistic aquatic and terrestrial food web bioaccumulation models for PFAS and (ii) an evaluation of model performance using available laboratory and field data. Model predictions of laboratory-measured bioconcentration factors and field-based bioaccumulation factors of PFAS in fish were in good agreement with observed data as measured by the mean model bias (MB), representing systematic over- or under-estimation and the standard deviation of the MB, representing general uncertainty. The models provide a mechanistic framework for evaluating the combined effect of simultaneously occurring uptake and elimination processes and indicate food web-specific magnification of PFAS, with the highest degree of biomagnification occurring in food webs composed of air-breathing wildlife. Albumin-water, structural protein-water, membrane-water distribution coefficients, and renal clearance rate are among the most important model parameters. With further development and testing, these models may be useful for future PFAS screening and risk assessment initiatives and advance bioaccumulation studies of PFAS by providing a mechanistic framework for PFAS bioaccumulation.

Legacy and alternative perfluoroalkyl acids in the Yellow River on the Qinghai-Tibet Plateau: Levels, spatiotemporal characteristics, and multimedia transport processes

The source region of the Yellow River (SRYR) located in the northeast of the Qinghai-Tibetan Plateau is not only the largest runoff-producing area in the Yellow River Basin, but also the most important freshwater-supply ecological function area in China. In this study, the short-term spatiotemporal distribution of selected legacy and alternative perfluoroalkyl acids (PFAAs) in the SRYR was first investigated in multiple environmental media. Total PFAA concentrations were in the range of 1.16-14.3 ng/L, 4.25-42.1 pg/L, and 0.21-13.0 pg/g dw in rainwater, surface water, and sediment, respectively. C4-C7 PFAAs were predominant in various environmental matrices. Spatiotemporal characteristics were observed in the concentrations and composition profiles. Particularly, the spatial distribution of rainwater and the temporal distribution of surface water exhibited highly significant differences (p<0.01). Indian monsoon, westerly air masses, and local mountain-valley breeze were the driving factors that contributed to the change of rainwater. Rainwater, meltwater runoff, and precursor degradation were important sources of PFAA pollution in surface water. Organic carbon content was a major factor influencing PFAA distribution in sediment. These results provide a theoretical basis for revealing the regional transport and fate of PFAAs, and are also important prerequisites for effectively protecting the freshwater resource and aquatic environment of the Qinghai-Tibetan Plateau.

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.

Per- and polyfluoroalkyl substances in Chinese commercially available red swamp crayfish (Procambarus clarkii): Implications for human exposure and health risk assessment

The extensive utilization of per- and polyfluoroalkyl substances (PFASs) has led to their pervasive presence in the environment, resulting in contamination of aquatic products. Prolonged exposure to PFASs has been linked to direct hepatic and renal damage, along with the induction of oxidative stress, contributing to a spectrum of chronic ailments. Despite the recent surge in popularity of red swamp crayfish as a culinary delicacy in China, studies addressing PFASs' exposure and associated health risks from their consumption remain scarce. To address this gap, our study investigated the PFASs' content in 85 paired edible tissue samples sourced from the five primary red swamp crayfish breeding provinces in China. The health risks associated with dietary exposure were also assessed. Our findings revealed widespread detection of PFASs in crayfish samples, with short-chain perfluoroalkyl carboxylic acids (PFCAs) exhibiting the highest concentrations. Notably, the total PFAS concentration in the hepatopancreas (median: 160 ng/g) significantly exceeded that in muscle tissue (5.95 ng/g), as did the concentration of every single substance. The hazard quotient of perfluorohexanesulfonic acid (PFHxS) via consuming crayfish during peak season exceeded 1. In this case, a potential total non-cancer health risk of PFASs, which is mainly from the hepatopancreas and associated with PFHxS, is also observed (hazard index>1). Thus, it is recommended to avoid consuming the hepatopancreas of red swamp crayfish. Greater attention should be paid to governance technology innovation and regulatory measure strengthening for short-chain PFASs.

Effects of PFAS on human liver transporters: implications for health outcomes

Per- and polyfluoroalkyl substances (PFAS) have become internationally recognized over the past three decades as persistent organic pollutants used in the production of various consumer and industrial goods. Research efforts continue to gauge the risk that historically used, and newly produced, PFAS may cause to human health. Numerous studies report toxic effects of PFAS on the human liver as well as increased serum cholesterol levels in adults. A major concern with PFAS, also dubbed "forever chemicals," is that they accumulate in the liver and kidney and persist in serum. The mechanisms responsible for their disposition and excretion in humans are poorly understood. A better understanding of the interaction of PFAS with liver transporters, as it pertains to the disposition of PFAS and other xenobiotics, could provide mechanistic insight into human health effects and guide efforts toward risk assessment of compounds in development. This review summarizes the current state of the literature on the emerging relationships (eg, substrates, inhibitors, modulators of gene expression) between PFAS and specific hepatic transporters. The adaptive and toxicological responses of hepatocytes to PFAS that reveal linkages to pathologies and epidemiological findings are highlighted. The evidence suggests that our understanding of the molecular landscape of PFAS must improve to determine their impact on the expression and function of hepatocyte transporters that play a key role in PFAS or other xenobiotic disposition. From here, we can assess what role these changes may have in documented human health outcomes.

Associations of Serum Per- and Polyfluoroalkyl Substances with Hyperuricemia in Adults: A Nationwide Cross-Sectional Study

There has been widespread concern about the health hazards of per- and polyfluoroalkyl substances (PFAS), which may be the risk factor for hyperuricemia with evidence still insufficient in the general population in China. Here, we conducted a nationwide study involving 9,580 adults aged 18 years or older from 2017 to 2018, measured serum concentrations of uric acid and PFAS (PFOA, PFOS, 6:2 Cl-PFESA, PFNA, PFHxS) in participants, to assess the associations of individual PFAS with hyperuricemia, and estimated a joint effect of PFAS mixtures. We found positive associations of higher serum PFAS with elevated odds of hyperuricemia in Chinese adults, with the greatest contribution from PFOA (69.37%). The nonmonotonic dose-response (NMDR) relationships were observed for 6:2 Cl-PFESA and PFHxS with hyperuricemia. Participants with less marine fish consumption, overweight, and obesity may be the sensitive groups to the effects of PFAS on hyperuricemia. We highlight the potential health hazards of legacy long-chain PFAS (PFOA) once again because of the higher weights of joint effects. This study also provides more evidence about the NMDR relationships in PFAS with hyperuricemia and emphasizes a theoretical basis for public health planning to reduce the health hazards of PFAS in sensitive groups.

Transformation of 6:6 PFPiA in the gut of Xenopus laevis: Synergistic effects of CYP450 enzymes and gut microflora

As a frequently detected per- and polyfluoroalkyl substance in the environment, 6:6 perfluoroalkylhypophosphinic acid (6:6 PFPiA) is vulnerable to transformation in the liver of organisms, but the transformation in gut is still unclear. This study investigates the molecular mechanisms of 6:6 PFPiA transformation in the gut of Xenopus laevis upon a 28-day exposure in water. Before Day 16, a notable correlation (p = 0.03) was observed between the transformation product (PFHxPA) and cytochrome P450 (CYP450) enzyme concentration in gut. This suggests that CYP450 enzymes played an important role in the transformation of 6:6 PFPiA in the gut, which was verified by an in vitro incubation with gut tissues, and supported by the molecular docking results of 6:6 PFPiA binding with CYP450 enzymes. From the day 16, the CYP450 concentration in gut decreased by 31.3 % due to the damage caused by 6:6 PFPiA, leading to a decrease in the transformation capacity in gut, but the transformation rate was stronger than in liver. This was in contrast with the in vitro experiment, where transformation was stronger in liver. In the mean time, the abundance of Bacteroidota in gut increased, which released hydrolytic enzyme and then could participate in the transformation as well. This study reveals the potential of the gut in metabolizing environmental pollutants, and provides profound insights into the potential health risks caused by 6:6 PFPiA in organisms.

Perfluorobutanoic acid triggers metabolic and transcriptional reprogramming in wheat seedlings

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

Linking exposure to per- and polyfluoroalkyl substances (PFAS) in house dust and biomonitoring data in eight impacted communities

Per- and polyfluoroalkyl substances (PFAS) are widely used in industry and have been linked to various adverse health effects. Communities adjacent to sites where PFAS are manufactured, stored, or used may be at elevated risk. In these impacted communities, significant exposure often occurs through contaminated drinking water, yet less is known about the role of other pathways such as residential exposure through house dust. We analyzed a paired serum and house dust dataset from the Agency for Toxic Substances and Disease Registry's PFAS Exposure Assessments, which sampled eight United States communities with a history of drinking water contamination due to aqueous film forming foam (AFFF) use at nearby military bases. We found that serum PFAS levels of residents were significantly positively associated with the dust PFAS levels in their homes, for three of seven PFAS analyzed, when accounting for site and participant age. We also found that increased dust PFAS levels were associated with a shift in the relative abundance of PFAS in serum towards those chemicals not strongly linked to AFFF contamination, which may suggest household sources. Additionally, we analyzed participant responses to exposure questionnaires to identify factors associated with dust PFAS levels. Dust PFAS levels for some analytes were significantly elevated in households where participants were older and had lived at the home longer, cleaned less frequently, used stain resistant products, and had carpeted living rooms. Our results suggest that residential exposure to PFAS via dust or other indoor pathways may contribute to overall exposure and body burden, even in communities impacted by AFFF contamination of drinking water, and the magnitude of this exposure may also be influenced by demographic, behavioral, and housing factors.

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.

Accumulation features and temporal trends (2002-2015) for legacy and emerging per- and polyfluoroalkyl substances (PFASs) in finless porpoises bycaught off Korean coasts

Legacy and emerging per- and polyfluoroalkyl substances (PFASs) were measured in livers of finless porpoises (Neophocaena asiaeorientalis; n = 167) collected in Korean waters from 2002 to 2015 to investigate their occurrence, bioaccumulation feature, temporal trends, and ecotoxicological implications. Perfulorooctane sulfonate (PFOS), perfluoroundecanoate (PFUnDA), and perfluorotridecanoate (PFTrDA) were the predominant PFASs found in the porpoises. The concentration of 6:2 chlorinated polyfluoroalkyl ether sulfonate (F-53B), an alternative to PFOS, was comparable to that of PFTrDA. Perfluorooctane sulfonamide (FOSA), a precursor of PFOS, was also detected in all the porpoises examined. All PFASs, including F-53B, accumulated to higher concentrations in immature porpoises compared with mature specimens, implying substantial maternal transfer and limited metabolizing capacity for PFASs. A significant correlation was observed between PFOS and F-53B concentrations, indicating similar bioaccumulation processes. Based on prenatal exposure and toxicity, F-53B is an emerging contaminant in marine ecosystems. Significantly increasing trends were observed in the concentrations of sulfonates, carboxylates, and F-53B between 2002/2003 and 2010, whereas the FOSA concentration significantly decreased. During 2010-2015, decreasing trends were observed in the concentrations of FOSA and sulfonates, whereas concentrations of carboxylate and F-53B increased without statistical significance, likely due to a gap for the implementation of regulatory actions between sulfonates and carboxylates. Although PFOS and PFOA were found to pose little health risk to porpoises, the combined toxicological effects of other contaminants should be considered to protect populations and to mitigate PFAS contamination in marine ecosystems.

Quantitative cross-species comparison of serum albumin binding of per- and polyfluoroalkyl substances from five structural classes

Per- and polyfluoroalkyl substances (PFAS) are a class of over 8000 chemicals, many of which are persistent, bioaccumulative, and toxic to humans, livestock, and wildlife. Serum protein binding affinity is instrumental in understanding PFAS toxicity, yet experimental binding data is limited to only a few PFAS congeners. Previously, we demonstrated the usefulness of a high-throughput, in vitro differential scanning fluorimetry assay for determination of relative binding affinities of human serum albumin for 24 PFAS congeners from 6 chemical classes. In the current study, we used this assay to comparatively examine differences in human, bovine, porcine, and rat serum albumin binding of 8 structurally informative PFAS congeners from 5 chemical classes. With the exception of the fluorotelomer alcohol 1H, 1H, 2H, 2H-perfluorooctanol (6:2 FTOH), each PFAS congener bound by human serum albumin was also bound by bovine, porcine, and rat serum albumin. The critical role of the charged functional headgroup in albumin binding was supported by the inability of albumin of each species tested to bind 6:2 FTOH. Significant interspecies differences in serum albumin binding affinities were identified for each of the bound PFAS congeners. Relative to human albumin, perfluoroalkyl carboxylic and sulfonic acids were bound with greater affinity by porcine and rat serum albumin, and the perfluoroalkyl ether acid congener bound with lower affinity to porcine and bovine serum albumin. These comparative affinity data for PFAS binding by serum albumin from human, experimental model, and livestock species reduce critical interspecies uncertainty and improve accuracy of predictive bioaccumulation and toxicity assessments for PFAS.

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

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

Species-Specific Unbound Fraction Differences in Highly Bound PFAS: A Comparative Study across Human, Rat, and Mouse Plasma and Albumin

Per- and polyfluoroalkyl substances (PFAS) are a diverse group of fluorinated compounds which have yet to undergo comprehensive investigation regarding potential adverse health effects and bioaccumulative properties. With long half-lives and accumulative properties, PFAS have been linked to several toxic effects in both non-clinical species such as rat and mouse as well as human. Although biological impacts and specific protein binding of PFAS have been examined, there is no study focusing on the species-specific fraction unbound (fu) in plasma and related toxicokinetics. Herein, a presaturation equilibrium dialysis method was used to measure and validate the binding of 14 individual PFAS with carbon chains containing 4 to 12 perfluorinated carbon atoms and several functional head-groups to albumin and plasma of mouse (C57BL/6 and CD-1), rat, and human. Equivalence testing between each species-matrix combination showed positive correlation between rat and human when comparing fu in plasma and binding to albumin. Similar trends in binding were also observed for mouse plasma and albumin. Relatively high Spearman correlations for all combinations indicate high concordance of PFAS binding regardless of matrix. Physiochemical properties of PFAS such as molecular weight, chain length, and lipophilicity were found to have important roles in plasma protein binding of PFAS.

Perfluoroalkyl acid precursors in agricultural soil-plant systems: Occurrence, uptake, and biotransformation

Perfluoroalkyl acid (PFAA) precursors have been used in various consumer and industrial products due to their hydrophobic and oleophobic properties. In recent years, PFAA precursors in agricultural soil-plant systems have received increasing attention as they are susceptible to biotransformation into metabolites with high biotoxicity risks to human health. In this review, we systematically assessed the occurrence of PFAA precursors in agricultural soils, taking into account their sources and biodegradation pathways. In addition, we summarized the findings of the relevant literature on the uptake and biotransformation of PFAA precursors by agricultural plants. The applications of biosolids/composts and pesticides are the main sources of PFAA precursors in agricultural soils. The physicochemical properties of PFAA precursors, soil organic carbon (SOC) contents, and plant species are the key factors influencing plant root uptakes of PFAA precursors from soils. This review revealed, through toxicity assessment, the potential of PFAA precursors to generate metabolites with higher toxicity than the parent precursors. The results of this paper provide a reference for future research on PFAA precursors and their metabolites in soil-plant systems.

Per- and polyfluoroalkyl substances (PFAS) in little penguins and associations with urbanisation and health parameters

Per- and Polyfluoroalkyl substances (PFAS) are increasingly detected in wildlife and present concerning and unknown health risks. While there is a growing body of literature describing PFAS in seabird species, knowledge from temperate Southern Hemisphere regions is lacking. Little penguins (Eudyptula minor) can nest and forage within heavily urbanised coastal environments and hence may be at risk of exposure to pollutants. We analysed scat contaminated nesting soils (n = 50) from 17 colonies in lutruwita/Tasmania for 16 PFAS, plasma samples (n = 45) from nine colonies, and three eggs for 49 PFAS. We detected 14 PFAS across the sample types, with perfluorooctanesulfonic acid (PFOS) and perfluorohexanesulfonic acid (PFHxS) most commonly detected. Mean concentration of PFOS in plasma was 2.56 ± 4.3 ng/mL ( Collapse

Key Words

• Ecotoxicology
• Genotoxicity
• Human impacts
• Seabird sentinels
• Wildlife health

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MESH Headings

• Male
• Female
• Animals
• Spheniscidae
• Urbanization
• Alkanesulfonic Acids/analysis
• Environmental Pollutants/analysis
• Fluorocarbons/analysis
• Soil
• Sulfonic Acids

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Affiliation(s)

Melanie R Wells Department of Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart 7001, Tasmania, Australia; Institute for Marine and Antarctic Studies, Battery Point 7004, Tasmania, Australia.
Timothy L Coggan Environment Protection Authority Victoria, 200 Victoria Street, Carlton 3053, Victoria, Australia; ADE Consulting Group, U 4/95 Salmon Street, Port Melbourne 3207, Victoria, Australia
Gavin Stevenson Australian Ultra-Trace Laboratory, National Measurement Institute, North Ryde 2113, New South Wales, Australia
Navneet Singh ADE Consulting Group, U 4/95 Salmon Street, Port Melbourne 3207, Victoria, Australia
Matthew Askeland ADE Consulting Group, U 4/95 Salmon Street, Port Melbourne 3207, Victoria, Australia
Mary-Anne Lea Institute for Marine and Antarctic Studies, Battery Point 7004, Tasmania, Australia; Centre for Marine Socioecology, University of Tasmania, Hobart 7001, Tasmania, Australia
Annie Philips Wildlife Veterinary Consultant, Hobart 7000, Tasmania, Australia
Scott Carver Department of Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart 7001, Tasmania, Australia; Odum School of Ecology, University of Georgia, GA, USA 30602; Center for the Ecology of Infectious Diseases, University of Georgia, GA, USA 30602

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