Combined effects and toxicological interactions of perfluoroalkyl and polyfluoroalkyl substances mixtures in human liver cells (HepG2)

Mixtures of legacy and replacement perfluorosulphonic acids (PFSAs) demonstrate ratio-, concentration- and endpoint-dependent synergistic interactions in vitro

The extensive use of poly- and per-fluoroalkyl substances (PFASs) has les to their widespread presence in the environment, raising concerns about potential toxicity. While certain PFASs of concern have been phased-out or banned, new PFASs continue to be produced. Two such substances are perfluoroethylcyclohexane sulphonate (PFECHS) and perfluorobutane sulphamide (FBSA), replacements of perfluoroctanesulphonic acid (PFOS) that have recently been detected in multiple environmental media around the globe. Despite PFASs generally occurring in the environment as mixtures, few data are available outlining the effects of PFAS mixtures. Therefore, this research investigated the interaction potential of binary and ternary mixtures of emerging and legacy PFASs. The immortalized rainbow trout gill cell line (RTgill-W1) was chosen as the experimental model to investigate two apical endpoints: cytotoxicity and phospholipidosis. RTgill-W1 cells were exposed for 24 h to each compound to obtain endpoint-specific effect concentrations (LCx; ECx). These values were then applied to formulate mixture predictions following the Loewes Additivity and Steel and Peckham methods. Based on cytotoxicity, relative potencies of individual compounds were: PFOS > PFECHS > FSBA. PFOS and PFECHS had nearly identical effects on phospholipidosis, while FSBA did not have any effects. Most mixtures had a synergistic effect on cytotoxicity, but the effect was both dose- and ratio-dependent. PFOS and PFECHS were additive at lower concentrations (LC10) and synergistic at higher concentrations (LC50; 3:1, 1:1, and 1:3). PFECHS and FSBA mixtures were synergistic at all doses and ratios (3:1, 1:1, 1:3), while FBSA and PFOS were mainly synergistic at higher concentrations and at ratios favouring PFOS (1:1, 1:3). Tertiary combinations were mainly synergistic. For phospholipidosis, mixtures were strictly additive. These results are strongly suggestive of synergism between emerging PFAS replacements and highlight that independent apical mechanisms of different PFASs could combine to induce unexpected toxicity. Considering that emerging replacements are continuing to increase in concentration in the environment, such mixture scenarios are also likely to continue to increase in probability.

Comparative toxicity assessment of alternative versus legacy PFAS: Implications for two primary trophic levels in freshwater ecosystems

Perfluoroalkyl substances (PFAS) are common environmental pollutants, but their toxicity framework remains elusive. This research focused on ten PFAS, evaluating their impacts on two ecotoxicologically relevant model organisms from distinct trophic levels: the crustacean Daphnia magna and the unicellular green alga Raphidocelis subcapitata. The results showed a greater sensitivity of R. subcapitata compared to D. magna. However, a 10-day follow-up to the 48 h immobilisation test in D. magna showed delayed mortality, underlining the limitations of relying on EC50 s from standard acute toxicity tests. Among the compounds scrutinized, Perfluorodecanoic acid (PFDA) was the most toxic to R. subcapitata, succeeded by Perfluorooctane sulfonate (PFOS), Perfluorobutanoic acid (PFBA), and Perfluorononanoic acid (PFNA), with the latter being the only one to show an algicidal effect. In the same species, assessment of binary mixtures of the compounds that demonstrated high toxicity in the single evaluation revealed either additive or antagonistic interactions. Remarkably, with an EC50 of 31 mg L-1, the short-chain compound PFBA, tested individually, exhibited toxicity levels akin to the notorious long-chain PFOS, and its harm to freshwater ecosystems cannot be ruled out. Despite mounting toxicological evidence and escalating environmental concentrations, PFBA has received little scientific attention and regulatory stewardship. It is strongly advisable that regulators re-evaluate its use to mitigate potential risks to the environmental and human health.

Nontarget Analysis of Legacy and Emerging PFAS in a Lithium-Ion Power Battery Recycling Park and Their Possible Toxicity Measured Using High-Throughput Phenotype Screening

Driven by the global popularity of electric vehicles and the shortage of critical raw materials for batteries, the spent lithium-ion power battery (LIPB) recycling industry has exhibited explosive growth in both quantity and scale. However, relatively little information is known about the environmental risks posed by LIPB recycling, in particular with regards to perfluoroalkyl and polyfluoroalkyl substances (PFAS). In this work, suspect screening and nontarget analysis were carried out to characterize PFAS in soil, dust, water and sediment from a LIPB recycling area. Twenty-five PFAS from nine classes were identified at confidence level 3 or above, including 13 legacy and 12 emerging PFAS, as well as two ultrashort-chain PFAS. Based on the target analysis of 16 PFAS, at least nine were detected in each environmental sample, indicating their widespread presence in a LIPB recycling area. Perfluorodecanoic acid, perfluorooctanesulfonic acid and trifluoromethanesulfonamide showed significant differences in the four phenotypic parameters (growth, movement, survival and fecundity) of Caenorhabditis elegans and were the most toxic substances in all target PFAS at an exposure concentration of 200 μM. Our project provides first-hand information on the existence and environmental risk of PFAS, facilitating the formulation of regulations and green development of the LIPB recycling industry.

A research synthesis of humans, animals, and environmental compartments exposed to PFAS: A systematic evidence map and bibliometric analysis of secondary literature

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are a class of widely used anthropogenic chemicals. Concerns regarding their persistence and potential adverse effects have led to multiple secondary research publications. Here, we aim to assess the resulting evidence base in the systematic secondary literature by examining research gaps, evaluating the quality of reviews, and exploring interdisciplinary connections.

METHODS

This study employed a systematic evidence-mapping approach to assess the secondary literature on the biological, environmental, and medical aspects of exposure to 35 fluorinated compounds. The inclusion criteria encompassed systematic reviews published in peer-reviewed journals, pre-prints, and theses. Comprehensive searches across electronic databases and grey literature identified relevant reviews. Data extraction and synthesis involved mapping literature content and narrative descriptions. We employed a modified version of the AMSTAR2 checklist to evaluate the methodological rigour of the reviews. A bibliometric data analysis uncovered patterns and trends in the academic literature. A research protocol for this study was previously pre-registered (osf.io/2tpn8) and published (Vendl et al., Environment International 158 (2022) 106973). The database is freely accessible through the interactive and user-friendly web application of this systematic evidence map at https://hi-this-is-lorenzo.shinyapps.io/PFAS_SEM_Shiny_App/.

RESULTS

Our map includes a total of 175 systematic reviews. Over the years, there has been a steady increase in the annual number of publications, with a notable surge in 2021. Most reviews focused on human exposure, whereas environmental and animal-related reviews were fewer and often lacked a rigorous systematic approach to literature search and screening. Review outcomes were predominantly associated with human health, particularly with reproductive and children's developmental health. Animal reviews primarily focused on studies conducted in controlled laboratory settings, and wildlife reviews were characterised by an over-representation of birds and fish species. Recent reviews increasingly incorporated quantitative synthesis methodologies. The methodological strengths of the reviews included detailed descriptions of study selection processes and disclosure of potential conflicts of interest. However, weaknesses were observed in the critical lack of detail in reporting methods. A bibliometric analysis revealed that the most productive authors collaborate within their own country, leading to limited and clustered international collaborations.

CONCLUSIONS

In this overview of the available systematic secondary literature, we map literature content, assess reviews' methodological quality, highlight data gaps, and draw research network clusters. We aim to facilitate literature reviews, guide future research initiatives, and enhance opportunities for cross-country collaboration. Furthermore, we discuss how this systematic evidence map and its publicly available database benefit scientists, regulatory agencies, and other stakeholders by providing access to current systematic secondary literature on PFAS exposure.

An environmentally relevant mixture of per- and polyfluoroalkyl substances (PFAS) impacts proliferation, steroid hormone synthesis, and gene transcription in primary human granulosa cells

Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic chemicals that are resistant to biodegradation and are environmentally persistent. PFAS are found in many consumer products and are a major source of water and soil contamination. This study investigated the effects of an environmentally relevant PFAS mixture (perfluorooctanoic acid [PFOA], perfluorooctanesulfonic acid [PFOS], perfluorohexanesulfonic acid [PFHxS]) on the transcriptome and function of human granulosa cells (hGCs). Primary hGCs were harvested from follicular aspirates of healthy, reproductive-age women who were undergoing oocyte retrieval for in vitro fertilization. Liquid Chromatography with tandem mass spectrometry (LC/MS-MS) was performed to identify PFAS compounds in pure follicular fluid. Cells were cultured with vehicle control or a PFAS mixture (2 nM PFHxS, 7 nM PFOA, 10 nM PFOS) for 96 h. Analyses of cell proliferation/apoptosis, steroidogenesis, and gene expression were measured via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays/immunofluorescence, ELISA/western blotting, and RNA sequencing/bioinformatics, respectively. PFOA, PFOS, and PFHxS were detected in 100% of follicle fluid samples. Increased cell proliferation was observed in hGCs treated with the PFAS mixture with no impacts on cellular apoptosis. The PFAS mixture also altered steroid hormone synthesis, increasing both follicle-stimulating hormone-stimulated and basal progesterone secretion and concomitant upregulation of STAR protein. RNA sequencing revealed inherent differences in transcriptomic profiles in hGCs after PFAS exposure. This study demonstrates functional and transcriptomic changes in hGCs after exposure to a PFAS mixture, improving our knowledge about the impacts of PFAS exposures and female reproductive health. These findings suggest that PFAS compounds can disrupt normal granulosa cell function with possible long-term consequences on overall reproductive health.

Multi-omics reveals the molecular mechanism of the combined toxic effects of PFOA and 4-HBP exposure in MCF-7 cells and the key player: mTORC1

With the discovery of evidence that many endocrine-disrupting chemicals (EDCs) in the environment influence human health, their toxic effects and mechanisms have become a hot topic of research. However, investigations into their endocrine-disrupting toxicity under combined binary exposure, especially the molecular mechanism of combined effects, have rarely been documented. In this study, two typical EDCs, perfluorooctanoic acid (PFOA) and 4-hydroxybenzophenone (4-HBP), were selected to examine their combined effects and molecular mechanism on MCF-7 cell proliferation at environmentally relevant exposure concentrations. We have successfully established a model to evaluate the binary combined toxic effects of endocrine disruptors, presenting combined effects in a simple and direct way. Results indicated that the combined effect changed from additive to synergistic from 1.25 × 10-8 M to 4 × 10-7 M. Metabolomics analyses suggested that exposure to PFOA and 4-HBP caused significant alterations in purine metabolism, arginine, and proline metabolism and had superimposed influences on metabolism. Enhanced combined effects were observed in glycine, serine, and threonine metabolic pathways compared to exposure to PFOS and 4-HBP alone. Additionally, the differentially expressed genes (DEGs) are primarily involved in Biological Processes, especially protein targeting the endoplasmic reticulum, and significantly impact the oxidative phosphorylation and thermogenesis-related KEGG pathway. By integrating metabolome and transcriptome analyses, PFOA and 4-HBP regulate purine metabolism, the TCA cycle, and endoplasmic reticulum protein synthesis in MCF-7 cells via mTORC1, which provides genetic material, protein, and energy for cell proliferation. Furthermore, molecular docking confirmed the ability of PFOA and 4-HBP to stably bind the estrogen receptor, indicating that they have different binding pockets. Collectively, these findings will offer new insights into understanding the mechanisms by which EDCs produce combined toxicity.

Distribution of per- and polyfluoroalkyl substances in blood, serum, and urine of patients with liver cancer and associations with liver function biomarkers

Studies have shown that per- and polyfluoroalkyl substances (PFASs) may be hepatotoxic in animals or humans. However, data on clinical epidemiology are very limited. In this study, 21 PFASs were determined in patients with liver diseases, with the highest median concentrations detected in the serum sample (26.7 ng/mL), followed by blood (10.7 ng/mL) and urine (5.02 ng/mL). Higher total PFAS concentrations were found in hepatocellular carcinoma (HCC) patients compared to non-HCC patients, with significant discrepancies in serum and blood samples. Besides, significant correlations were also found among PFAS concentrations and age, gender, body mass index (BMI), and liver function biomarkers levels. For example, PFAS concentrations are significantly higher in males than in females; Several serum PFASs concentrations increase with age and BMI, while the serum perfluorohexane sulfonic acid (PFHxS) concentrations are negatively correlated with age. In addition, multiple regression models adjusted for age, gender and BMI found that increased serum perfluorobutane sulfonic acid (PFBS), perfluoroheptane sulfonic acid (PFHpS) and perfluorohexylphosphonic acid (PFHxPA) conentrations are correlated with elevated alkaline phosphatase (ALP), aspartate aminotransferase (AST), and alpha-fetoprotein (AFP) (p < 0.05). Our results provide epidemiological support for the future study on the potential clinical hepatotoxicity of PFAS.

Evidence on the genotoxic and ecotoxic effects of PFOA, PFOS and their mixture on human lymphocytes and bacteria

Considering that the PFOA and PFOS are widely spread chemicals with harmful effects in human and environmental health as well as the increasing interest of the scientific community in the implications that might present especially when they co-exist, this study aims to assess their harmful impacts, both individually and as a mixture on human lymphocytes and aquatic microorganisms. The cytokinesis-block micronucleus (CBMN) assay was used to examine their potential for cytotoxicity and genotoxicity towards human cells, and Microtox assay using Aliivibrio fischeri assay was used to estimate the environmental risk. Regarding the human lymphocytes, the tested concentrations ranged between 250 and 1000 μg L-1, for all cases. PFOA increased slightly the frequency of micronuclei (MN) but without statistical significance. In the case of PFOS, our results showed a dose-dependent increase in the frequency of micronuclei which showed a statistically significant difference (p < 0.001) at 1000 μg L-1, which is the highest studied concentration. Regarding the CBPI index, statistically significant (p < 0.05, p < 0.01, and p < 0.001 respectively) differences were observed at all studied concentrations of PFOS, compared to the control. The mixture was found to be more cytotoxic and genotoxic than the individual tested compounds, causing a higher decrease at the CBPI index even in lower concentrations and increase at the MN frequencies. Aliivibrio fischeri was exposed to various concentrations in the range of 0.5 μg L-1- 20 mg L-1, for 5 and 15 min and significant increase in the inhibition percentage at the highest tested concentration of their mixture after 15 min was observed.

All-cause, cardiovascular disease and cancer mortality in the population of a large Italian area contaminated by perfluoroalkyl and polyfluoroalkyl substances (1980-2018)

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are associated with many adverse health conditions. Among the main effects is carcinogenicity in humans, which deserves to be further clarified. An evident association has been reported for kidney cancer and testicular cancer. In 2013, a large episode of surface, ground and drinking water contamination with PFAS was uncovered in three provinces of the Veneto Region (northern Italy) involving 30 municipalities and a population of about 150,000. We report on the temporal evolution of all-cause mortality and selected cause-specific mortality by calendar period and birth cohort in the local population between 1980 and 2018.

METHODS

The Italian National Institute of Health pre-processed and made available anonymous data from the Italian National Institute of Statistics death certificate archives for residents of the provinces of Vicenza, Padua and Verona (males, n = 29,629; females, n = 29,518) who died between 1980 and 2018. Calendar period analysis was done by calculating standardised mortality ratios using the total population of the three provinces in the same calendar period as reference. The birth cohort analysis was performed using 20-84 years cumulative standardised mortality ratios. Exposure was defined as being resident in one of the 30 municipalities of the Red area, where the aqueduct supplying drinking water was fed by the contaminated groundwater.

RESULTS

During the 34 years between 1985 (assumed as beginning date of water contamination) and 2018 (last year of availability of cause-specific mortality data), in the resident population of the Red area we observed 51,621 deaths vs. 47,731 expected (age- and sex-SMR: 108; 90% CI: 107-109). We found evidence of raised mortality from cardiovascular disease (in particular, heart diseases and ischemic heart disease) and malignant neoplastic diseases, including kidney cancer and testicular cancer.

CONCLUSIONS

For the first time, an association of PFAS exposure with mortality from cardiovascular disease was formally demonstrated. The evidence regarding kidney cancer and testicular cancer is consistent with previously reported data.

Short-term mass loads of per- and polyfluoroalkyl substances in a wastewater treatment plant from South China

Wastewater treatment plants (WWTPs) are one of the most important sources and sinks for per- and polyfluoroalkyl substances (PFAS). However, limited studies have evaluated short-term temporal variability of PFAS in WWTPs, particularly for their intra-day variations. For this purpose, a time-composite sampling campaign was carried out at a WWTP influent from South China for 1 week. Five out of ten PFAS were found in the influent, i.e., perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorobutane sulfonic acid (PFBS), and perfluorooctanesulfonic acid (PFOS). PFOA was the most domain PFAS whereas PFOS was detected occasionally, which might be associated with the prohibition of PFOS use in China. For the first time, we observed significant intra-day fluctuations in mass fluxes for PFOS. Different from a morning peak of pharmaceuticals reported previously, PFOS mass loads fluctuated sharply at noon and night on the weekdays. Furthermore, the mass fluxes of PFOA on the weekend were significantly elevated. For the other PFAS detected, no significant diurnal variations in mass loads were identified. Correlation analysis indicated that domestic activities (e.g., home cleaning) are likely to be the major source of these perfluorocarboxylic acids especially PFOA. In addition, flow fluxes had little effects on these PFAS mass load. These results can aid in future sampling campaigns and optimizing removal strategies for PFAS in wastewater.

Hazard and risk characterization of 56 structurally diverse PFAS using a targeted battery of broad coverage assays using six human cell types

Per- and poly-fluoroalkyl substances (PFAS) are extensively used in commerce leading to their prevalence in the environment. Due to their chemical stability, PFAS are considered to be persistent and bioaccumulative; they are frequently detected in both the environment and humans. Because of this, PFAS as a class (composed of hundreds to thousands of chemicals) are contaminants of very high concern. Little information is available for the vast majority of PFAS, and regulatory agencies lack safety data to determine whether exposure limits or restrictions are needed. Cell-based assays are a pragmatic approach to inform decision-makers on potential health hazards; therefore, we hypothesized that a targeted battery of human in vitro assays can be used to determine whether there are structure-bioactivity relationships for PFAS, and to characterize potential risks by comparing bioactivity (points of departure) to exposure estimates. We tested 56 PFAS from 8 structure-based subclasses in concentration response (0.1-100 μM) using six human cell types selected from target organs with suggested adverse effects of PFAS - human induced pluripotent stem cell (iPSC)-derived hepatocytes, neurons, and cardiomyocytes, primary human hepatocytes, endothelial and HepG2 cells. While many compounds were without effect; certain PFAS demonstrated cell-specific activity highlighting the necessity of using a compendium of in vitro models to identify potential hazards. No class-specific groupings were evident except for some chain length- and structure-related trends. In addition, margins of exposure (MOE) were derived using empirical and predicted exposure data. Conservative MOE calculations showed that most tested PFAS had a MOE in the 1-100 range; ∼20% of PFAS had MOE<1, providing tiered priorities for further studies. Overall, we show that a compendium of human cell-based models can be used to derive bioactivity estimates for a range of PFAS, enabling comparisons with human biomonitoring data. Furthermore, we emphasize that establishing structure-bioactivity relationships may be challenging for the tested PFAS.

In Vitro Toxicity Screening of Fifty Complex Mixtures in HepG2 Cells

To develop the risk prediction technology for mixture toxicity, a reliable and extensive dataset of experimental results is required. However, most published literature only provides data on combinations containing two or three substances, resulting in a limited dataset for predicting the toxicity of complex mixtures. Complex mixtures may have different mode of actions (MoAs) due to their varied composition, posing difficulty in the prediction using conventional toxicity prediction models, such as the concentration addition (CA) and independent action (IA) models. The aim of this study was to generate an experimental dataset comprising complex mixtures. To identify the target complex mixtures, we referred to the findings of the HBM4EU project. We identified three groups of seven to ten components that were commonly detected together in human bodies, namely environmental phenols, perfluorinated compounds, and heavy metal compounds, assuming these chemicals to have different MoAs. In addition, a separate mixture was added consisting of seven organophosphate flame retardants (OPFRs), which may have similar chemical structures. All target substances were tested for cytotoxicity using HepG2 cell lines, and subsequently 50 different complex mixtures were randomly generated with equitoxic mixtures of EC10 levels. To determine the interaction effect, we calculated the model deviation ratio (MDR) by comparing the observed EC10 with the predicted EC10 from the CA model, then categorized three types of interactions: antagonism, additivity, and synergism. Dose-response curves and EC values were calculated for all complex mixtures. Out of 50 mixtures, none demonstrated synergism, while six mixtures exhibited an antagonistic effect. The remaining mixtures exhibited additivity with MDRs ranging from 0.50 to 1.34. Our experimental data have been formatted to and constructed for the database. They will be utilized for further research aimed at developing the combined CA/IA approaches to support mixture risk assessment.

PFAS: exploration of neurotoxicity and environmental impact

Per- and polyfluoroalkyl substances (PFAS) are widespread contaminants stemming from various industrial and consumer products, posing a grave threat to both human health and ecosystems. PFAS contamination arises from multiple sources, including industrial effluents, packaging, and product manufacturing, accumulating in plants and impacting the food chain. Elevated PFAS levels in water bodies pose significant risks to human consumption. This review focuses on PFAS-induced neurological effects, highlighting disrupted dopamine signalling and structural neuron changes in humans. Animal studies reveal apoptosis and hippocampus dysfunction, resulting in memory loss and spatial learning issues. The review introduces the BKMR model, a machine learning technique, to decipher intricate PFAS-neurotoxicity relationships. Epidemiological data underscores the vulnerability of young brains to PFAS exposure, necessitating further research. Stricter regulations, industry monitoring, and responsible waste management are crucial steps to reduce PFAS exposure.

Association between exposure to per- and perfluoroalkyl substances (PFAS) and reproductive hormones in human: A systematic review and meta-analysis

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) is persistent endocrine disrupting chemicals. Previous evidence suggests that exposure to PFAS is associated with reproductive hormone levels, but the results of relevant studies are inconsistent. The objective of our study is to determine the association between exposure to PFAS and reproductive hormone levels in gender-specific general population.

METHOD

Based on scientific search strategies, we systematically searched PubMed, Web of Science, Embase, Medline, and Scopus to obtain the eligible studies published before January 21, 2023. The quality of the included articles was assessed using the Office of Health Assessment and Translation (OHAT) Risk of Bias tool. We combined the β coefficient and 95% confidence intervals (CI) using Stata.17 with random-effect model or fixed-effect model. We also performed subgroup analysis, sensitivity analysis, and Begger's and Egger's tests.

RESULTS

Eleven studies involving 7714 participants were included. Meta-analysis showed that PFHxS exposure was positively associated with estradiol (E2) levels in female [β = 0.030, 95% CI: (0.013, 0.046), P = 0.000]. A negative association was found between PFOA [β = -0.012, 95% CI: (-0.023, -0.002), P = 0.017] and PFOS [β = -0.011; 95% CI: (-0.021, -0.000), P = 0.042] exposure with male testosterone (TT) levels. In the subgroup analysis, there were stronger associations in children than in adults. And the high heterogeneity was mainly due to the cross-sectional studies. Publication bias was not found in most of the analyses.

CONCLUSION

Our study showed that PFAS exposure was significantly associated with reproductive hormone levels. Further related studies are needed to identify the association and potential mechanism in the future.

Dietary exposure to per- and polyfluoroalkyl substances: Potential health impacts on human liver

Per- and polyfluoroalkyl substances (PFAS), dubbed "forever chemicals", are widely present in the environment. Environmental contamination and food contact substances are the main sources of PFAS in food, increasing the risk of human dietary exposure. Numerous epidemiological studies have established the link between dietary exposure to PFAS and liver disease. Correspondingly, PFAS induced-hepatotoxicity (e.g., hepatomegaly, cell viability, inflammation, oxidative stress, bile acid metabolism dysregulation and glycolipid metabolism disorder) observed from in vitro models and in vivo rodent studies have been extensively reported. In this review, the pertinent literature of the last 5 years from the Web of Science database was researched. This study summarized the source and fate of PFAS, and reviewed the occurrence of PFAS in food system (natural and processed food). Subsequently, the characteristics of human dietary exposure PFAS (population characteristics, distribution trend, absorption and distribution) were mentioned. Additionally, epidemiologic evidence linking PFAS exposure and liver disease was alluded, and the PFAS-induced hepatotoxicity observed from in vitro models and in vivo rodent studies was comprehensively reviewed. Lastly, we highlighted several critical knowledge gaps and proposed future research directions. This review aims to raise public awareness about food PFAS contamination and its potential risks to human liver health.

Adipogenic and osteogenic effects of OBS and synergistic action with PFOS via PPARγ-RXRα heterodimers

Sodium p-perfluorous nonenoxybenzenesulfonate (OBS) is a novel alternative to perfluorooctane sulfonate (PFOS), with environmental health risks largely unknown. The present study aims to unravel the adipogenesis effects and underlying molecular initiating events of OBS, which are crucial for understanding and predicting its adverse outcome. In undifferentiated human mesenchymal stem cells (hMSCs), exposure to 1-100 nM of OBS for 7 days stimulated reactive oxygen species production. In the subsequent multipotent differentiation, hMSCs favored adipogenesis and repressed osteogenesis. The point of departure (PoD) for cellular responses of OBS was 38.85 nM, higher than PFOS (0.39 nM). Notably, OBS/PFOS co-exposure inhibited osteogenesis and synergistically promoted adipogenesis. Consistently, the expression of adipogenic marker genes was up-regulated, while that of osteogenic marker genes was down-regulated. The decreased adiponectin and elevated tumor necrosis factor α (TNFα) secretion were observed in differentiated cells exposed to the mixture of OBS and PFOS. The co-treatment of a peroxisome proliferator-activated receptor γ (PPARγ) antagonist alleviated the adipogenic effects of PFOS and its combination with OBS. Moreover, OBS/PFOS co-exposure induced peroxisome PPARγ activation in reporter gene assays, and increased formation of PPARγ - retinoid X receptor α (RXRα) heterodimers measured by co-immunoprecipitation assays. Molecular docking showed interaction energy of OBS (-20.7 kcal/mol) with intact PPARγ-RXRα complex was lower than that of PFOS (-25.9 kcal/mol). Overall, single OBS exhibited lower potency in inducing adipogenesis but is comparable to PFOS in repressing osteogenesis, whereas OBS/PFOS co-exposure increases interaction with PPARγ-RXRα heterodimers, resulting in the synergistic activation of PPARγ, ultimately enhancing adipogenesis at the expense of osteogenic differentiation. The results indicate the potential health risks of increased obesity and decreased bone density caused by OBS and its co-exposure with PFOS, as well as other perfluorinated alkylated substances mixtures.

Analytical methods employed in the identification and quantification of per- and polyfluoroalkyl substances in human matrices - A scoping review

Persistent organic pollutants (POPs) represent a possible hazard for the ecosystems, with adverse outcomes on wildlife and humans. POPs have always received interest from the scientific community, and they have also been subject to legal restrictions worldwide on their application and commercialization. Among the broad spectrum of POPs, per- and polyfluoroalkyl substances (PFASs) are considered emerging contaminants due to their potential effect on the ecosystem and human health. These contaminants are widely employed in countless applications, from surfactants and building materials to food packaging. On the other hand, their chemical structure gives them the ability to interact with the environment, causing possible toxic effects for humans and environment. Human biomonitoring is a necessary instrument to indagate the impact of PFASs on human health: in recent years several studies have found detectable levels of PFASs in several biological matrices in humans (blood, hair, nails, and urine). Here, we review the most recent scientific literature concerning analytical methods employed in the identification and quantification of PFASs focusing on biological matrices. It has been noted that liquid chromatography coupled with mass spectrometry is the main analytical instrumentation employed, while blood and/or serum samples are the main employed human matrices whereas the use of non-invasive matrices is still at the beginning. Various issues directly related to human metabolism of PFASs and the effective amount of PFAS absorbed from the environment still need to be investigated.

Concentrations and association between exposure to mixed perfluoroalkyl and polyfluoroalkyl substances and glycometabolism among adolescents

BACKGROUND

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are widely used for industrial and commercial purposes and have received increasing attention due to their adverse effects on health.

OBJECTIVE

To examine the relationship of serum PFAS and glycometabolism among adolescents based on the US National Health and Nutrition Examination Survey.

METHODS

General linear regression models were applied to estimate the relationship between exposure to single PFAS and glycometabolism. Weighted quantile sum (WQS) regression models and Bayesian kernel machine regressions (BKMR) were used to assess the associations between multiple PFASs mixture exposure and glycometabolism.

RESULTS

A total of 757 adolescents were enrolled. Multivariable regression model showed that Me-PFOSA-AcOH exposure was negatively associated with fasting blood glucose. WQS index showed that there was marginal negative correlation between multiple PFASs joint exposure and the homeostasis model of assessment for insulin resistance index (HOMA-IR) (β = -0.26, p < .068), and PFHxS had the largest weight. BKMR models showed that PFASs mixture exposure were associated with decreased INS and HOMA-IR, and the exposure-response relationship had curvilinear shape.

CONCLUSIONS

The increase in serum PFASs were associated with a decrease in HOMA-IR among adolescents. Mixed exposure models could more accurately and effectively reveal true exposure.Key MessagesThe detection rates of different PFAS contents in adolescent serum remained diverse.Adolescent serum PFASs had negative curvilinear correlation with INS and HOMA-IR levels.PFHxS had the highest weight in the associations between multiple PFASs and adolescent glycometabolism.

Environmental impacts, exposure pathways, and health effects of PFOA and PFOS

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals that have been widely utilized in various industries since the 1940s, and have now emerged as environmental contaminants. In recent years, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) have been restricted and replaced with several alternatives. The high persistence, bioaccumulation, and toxicity of these substances have contributed to their emergence as environmental contaminants, and several aspects of their behavior remain largely unknown and require further investigation. The trace level of PFAS makes the development of a monitoring database challenging. Additionally, the potential health issues associated with PFAS are not yet fully understood due to ongoing research and inadequate evidence (experimental and epidemiological studies), especially with regard to the combined effects of exposure to PFAS mixtures and human health risks from drinking water consumption. This in-depth review offers unprecedented insights into the exposure pathways and toxicological impacts of PFAS, addressing critical knowledge gaps in their behaviors and health implications. It presents a comprehensive NABC-Needs, Approach, Benefits, and Challenges-analysis to guide future strategies for the sustainable monitoring and management of these pervasive environmental contaminants.

Serum albumin mitigated perfluorooctane sulfonate-induced cytotoxicity by affecting the cellular responses

During the wide applications of perfluorinated materials such as perfluorooctane sulfonate (PFOS) in commercial and industrial products, the potential toxicity of these engineered compounds has attracted more and more attention. As a typical environmental pollutant, PFOS could preferentially bind to albumin protein in vivo. However, the role of protein-PFOS interactions in the cytotoxicity of PFOS was not stressed enough. Herein, we investigated the interactions of PFOS with human serum albumin (HSA, the most abundant protein in human plasma) using both experimental and theoretical approaches. It was demonstrated that PFOS could mainly bind to the Sudlow site I of HSA to generate HSA-PFOS complex through hydrogen bonds and van der Waals forces. Toxicity assays with endothelial cells illustrated that the binding of HSA could significantly attenuate the intracellular uptake and subcellular distribution of PFOS, thereby inhibiting the formation of reactive oxygen species and toxicity for those HSA-bound PFOS. Similarly, the presence of fetal bovine serum in the cell culture media greatly reduced PFOS-caused cytotoxicity. Conclusively, our study reveals that the binding of albumin protein to PFOS could mitigate its toxicity by the modulation of cellular responses. The formation of protein-complexed contaminants would significantly reduce the bioavailability of these chemicals and subsequently mitigate their environmental toxicology to the human health.

Associations between per- and polyfluoroalkyl substances, liver function, and daily alcohol consumption in a sample of U.S. adults

BACKGROUND AND AIM

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in the environment and in the serum of the U.S.

POPULATION

We sought to evaluate the association of PFAS independently and jointly with alcohol intake on liver function biomarkers in a sample of the U.S. general population.

METHODS

Using data from the National Health and Nutrition Examination Survey (2003-2016; N = 11,794), we examined the five most historically prevalent PFAS with >75% detection rates. We estimated odds ratios (OR) and 95% confidence intervals (CI) for the association between PFAS (quartiles and log-transformed continuous, ng/mL) and high levels (>95th percentile) of liver injury biomarkers using logistic regression models adjusted for key confounders. We evaluated interactions between PFAS and alcohol consumption and sex via stratified analyses and conducted sub-analyses adjusting for daily alcohol intake among those with available drinking history (N = 10,316).

RESULT

Serum perfluorooctanoic acid (PFOA) was positively associated with high levels of alanine transferase (ALT) without monotonic trend (ORQ4vsQ1 = 1.45, CI: 0.99-2.12; p-trend = 0.18), and with increased aspartate transaminase when modeled continuously (OR = 1.15, CI: 1.02-1.30; p-trend = 0.03). Perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) were both inversely associated with alkaline phosphatase while a trend was evident only for PFHxS (p = 0.02). A non-monotonic inverse association was observed with PFOA (p-trend = 0.10). The highest quartile of PFOS was associated with high total bilirubin (TB; ORQ4vsQ1 = 1.57, CI: 1.01-2.43, p-trend = 0.02). No significant associations were found between any PFAS and γ-glutamyl transpeptidase. We found no associations for perfluorodecanoic acid and perfluorononanoic acid. We observed some suggestive interactions with alcohol intake, particularly among heavy drinkers.

CONCLUSION

Consistent with other studies, serum levels of PFOA, PFHxS and PFNA were positively associated with high levels of ALT, and we also observed weak positive associations between some PFAS and TB. Associations observed among heavy drinkers warrant additional evaluation.

The regulation of endocrine-disrupting chemicals to minimize their impact on health

Endocrine-disrupting chemicals (EDCs) are substances generated by human industrial activities that are detrimental to human health through their effects on the endocrine system. The global societal and economic burden posed by EDCs is substantial. Poorly defined or unenforced policies can increase human exposure to EDCs, thereby contributing to human disease, disability and economic damage. Researchers have shown that policies and interventions implemented at both individual and government levels have the potential to reduce exposure to EDCs. This Review describes a set of evidence-based policy actions to manage, minimize or even eliminate the widespread use of these chemicals and better protect human health and society. A number of specific challenges exist: defining, identifying and prioritizing EDCs; considering the non-linear or non-monotonic properties of EDCs; accounting for EDC exposure effects that are latent and do not appear until later in life; and updating testing paradigms to reflect 'real-world' mixtures of chemicals and cumulative exposure. A sound strategy also requires partnering with health-care providers to integrate strategies to prevent EDC exposure in clinical care. Critical next steps include addressing EDCs within global policy frameworks by integrating EDC exposure prevention into emerging climate policy.

Spirulina (Arthrospira maxima) mitigates the toxicity induced by a mixture of metal and NSAID in Xenopus laevis

Cadmium (Cd) is often detected in the environment due to its wide use in industry; also, NSAIDs are one of the most consumed pharmaceuticals, particularly diclofenac (DCF). Several studies have reported the presence of both contaminants in water bodies at concentrations ranging from ng L-1 to μg L-1; in addition, they have shown that they can induce oxidative stress in aquatic species and disturb signal transduction, cell proliferation, and intercellular communication, which could lead to teratogenesis. Spirulina has been consumed as a dietary supplement; its antioxidant, anti-inflammatory, neuroprotective, and nutritional properties are well documented. This work aimed to evaluate if Spirulina reduces the damage induced by Cd and DCF mixture in Xenopus laevis at early life stages. FETAX assay was carried out: 20 fertilized oocytes were exposed to seven different treatments on triplicate, control, Cd (24.5 μg L-1), DCF (149 μg L-1), Cd + DCF, Cd+DCF+Spirulina (2 mg L-1), Cd+DCF+Spirulina (4 mg L-1), Cd+DCF+Spirulina (10 mg L-1), malformations, mortality, and growth were evaluated after 96 h, also lipid peroxidation, superoxide dismutase and catalase activity were determined after 192 h. Cd increased DCF mortality, Cd and DCF mixture increased the incidence of malformations as well as oxidative damage; on the other hand, the results obtained show that Spirulina can be used to reduce the damage caused by the mixture of Cd and DCF since it promotes growth, reduce mortality, malformations, and oxidative stress in X. laevis.

Occurrence of legacy and alternative per- and polyfluoroalkyl substances in serum from high exposure population and their disrupting effects on serum lipids and thyroid function

High exposure of per- and polyfluoroalkyl substances (PFAS) has been reported in main chemical production areas in China, while epidemiological study on exposure risk of PFAS is still limited. In this study, legacy and alternative PFAS were measured in serum samples from 161 adults living in Laizhou Bay, a famous chemical production area located in Shandong province, Northern China. Based on the concentrations of serum PFAS, the disrupting effects of PFAS on serum lipids and thyroid function were further explored. The results showed that the serum perfluorooctanoic acid (PFOA) (geometric mean (GM): 60 ng/mL) in this region was even higher than serum PFOA of residents living in PFOA contaminated water districts in United States and Sweden. 100 % of the serum PFOA was higher than the reference dose for increased total cholesterol (TC). Consistently, higher serum PFOA was marginally correlated with increased TC level (p = 0.062) and low-density lipoprotein (p = 0.065). In addition, higher perfluoroisopropyl perfluorooctanesulfonate and 6:2 chlorinated polyfluoroalkyl ether sulfonates (6,2 Cl-PFESA) were significantly correlated with increased high-density lipoprotein (p = 0.040, 0.022). No significant association was observed between individual PFAS and any thyroid function biomarker. However, using the principal component analysis derived factors to represent the co-exposure patterns, co-exposure of legacy long-chain PFAS showed synergistic effects on the free thyroxine, while the mixture of alternative PFAS showed a synergistic influence on the total and free triiodothyronine.

Short-chain per- and polyfluoralkyl substances (PFAS) effects on oxidative stress biomarkers in human liver, kidney, muscle, and microglia cell lines

Long-chain per- and polyfluoralkyl substances (PFAS) are ubiquitous contaminants implicated in the induction of intracellular reactive oxygen species (ROS), compromising antioxidant defense mechanisms in vitro and in vivo. While a handful of studies have assessed oxidative stress effects by PFAS, few specifically address short-chain PFAS. We conducted an evaluation of oxidative stress biomarkers in vitro following exposures to low (1 nM) and high (1 μM) concentrations of five short-chain PFAS compounds: perfluorobutanesulfonic acid (PFBS), perfluorohexanoic acid (PFHxA), [undecafluoro-2-methyl-3-oxahexanoic acid (HFPO-DA)], 6:2 fluorotelomer alcohol (6:2 FTOH) and perfluorohexanesulfonic acid (PFHxS). We conducted experiments in human kidney (HEK293-hTLR2), liver (HepaRG), microglia (HMC-3), and muscle (RMS-13) cell lines. Fluorescence microscopy measurements in HepaRG cells indicated ROS generation in cells exposed to PFBS and PFHxA for 24 h. Antioxidant enzyme activities were determined following 24 h short-chain PFAS exposures in HepaRG, HEK293-hTLR2, HMC-3, and RMS-13. Notably, exposure to PFBS for 24 h increased the activity of GPX in all four cell types at 1 μM and 1 nM in HepaRG and RMS-13 cells. Every short-chain PFAS evaluated, except for PFHxS, increased the activity of at least one antioxidant enzyme. To our knowledge, this is the first study of its kind to explore antioxidant defense alterations to microglia and muscle cell lines by PFAS. The findings of this study hold great potential to contribute to the limited understanding of short-chain PFAS mechanisms of toxicity and provide data necessary to inform the human health risk assessment process.

Association of perfluoroalkyl substances with pulmonary function in adolescents (NHANES 2007-2012)

Perfluoroalkyl substances (PFASs) constitute an environmentally persistent and widespread class of anthropogenic chemicals that have been used in industrial and commercial applications in the USA and around the world. Animal studies suggested its toxic impact on lung development, but the adverse effect of PFAS exposure on childhood pulmonary function has not been clearly determined. We investigated the potential cross-sectional association of environmental PFAS exposures with pulmonary function in 765 adolescents aged 12-19 years from the US National Health and Nutrition Examination Survey (NHANES) 2007-2012. Exposure to PFASs was estimated by measuring serum concentrations, and pulmonary function was assessed by spirometry. Linear regression and weighted quantile sum (WQS) regression were performed to estimate the associations of individual chemicals and chemical mixtures with pulmonary function. Median concentrations of PFOA, PFOS, PFNA, and PFHxS (detection frequencies > 90%) were 2.70, 6.40, 0.98, and 1.51 ng/mL, respectively. No associations were found between the four individual congeners and Σ₄PFASs and the pulmonary function measures in total adolescents. Sensitive analyses were further conducted stratified by age (12-15 and 16-19 years) and sex (boys and girls). In adolescents aged 12-15 years, PFNA was negatively associated with FEV₁:FVC (p-trend = 0.007) and FEF_25-75% (p-trend = 0.03) among girls, while PFNA was positively associated with FEV₁: FVC (p-trend = 0.018) among boys. No associations were found among adolescents aged 16-19 years, either boys or girls. The aforementioned associations were confirmed when further applying WQS models, and PFNA was identified to be the most heavily weighing chemical. Our results suggested that environmental exposure to PFNA may affect pulmonary function among adolescents aged 12-15 years. Given the cross-sectional analysis and less consistent results, further replications of the association in large prospective cohort studies are warranted.

Mediation effects of DNA methylation and hydroxymethylation on birth outcomes after prenatal per- and polyfluoroalkyl substances (PFAS) exposure in the Michigan mother-infant Pairs cohort

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are chemicals that are resistant to degradation and ubiquitous in our environments. PFAS may impact the developing epigenome, but current human evidence is limited to assessments of total DNA methylation. We assessed associations between first trimester PFAS exposures with newborn DNA methylation, including 5-methylcytosine (5-mC) and 5-hydroxymethylcytosine (5-hmC). DNA methylation mediation of associations between PFAS and birth outcomes were explored in the Michigan Mother Infant Pairs cohort. Nine PFAS were measured in maternal first trimester blood. Seven were highly detected and included for analysis: PFHxS, PFOA, PFOS, PFNA, PFDA, PFUnDA, and MeFOSAA. Bisulfite-converted cord blood DNA (n = 141) and oxidative-bisulfite-converted cord blood (n = 70) were assayed on Illumina MethylationEPIC BeadChips to measure total DNA methylation (5-mC + 5-hmC) and 5-mC/5-hmC. Correcting for multiple comparisons, beta regressions were used to assess associations between levels of PFAS and total methylation, 5-mC, or 5-hmC. Nonlinear mediation analyses were used to assess the epigenetic meditation effect between PFAS and birth outcomes.

RESULTS

PFAS was significantly associated with total methylation (q < 0.05: PFHxS-12 sites; PFOS-19 sites; PFOA-2 sites; PFNA-3 sites; PFDA-4 sites). In 72 female infants and 69 male infants, there were sex-specific associations between five PFAS and DNA methylation. 5-mC and 5-hmC were each significantly associated with thousands of sites for PFHxS, PFOS, PFNA, PFDA, PFUnDA, and MeFOSAA (q < 0.05). Clusters of 5-mC and 5-hmC sites were significant mediators between PFNA and PFUnDA and decreased gestational age (q < 0.05).

CONCLUSIONS

This study demonstrates the mediation role of specific types of DNA methylation on the relationship between PFAS exposure and birth outcomes. These results suggest that 5-mC and 5-hmC may be more sensitive to the developmental impacts of PFAS than total DNA methylation.

Alteration of hepato-lipidomic homeostasis in A/J mice fed an environmentally relevant PFAS mixture

In the present study, we have investigated liver lipid homeostasis and corresponding changes in transcript and functional product levels in A/J mice exposed to environmental relevant concentration of per- and polyfluoroalkyl substances (PFAS) mixture. Mice were fed environmentally relevant concentrations of a PFAS mixture during a period of 10 weeks. The concentrations of the 8 individual PFAS in the mixture were chosen based on measured concentrations in earthworms at a Norwegian skiing area. Our data show high liver accumulation of ∑PFAS in exposed mice, which paralleled significant elevation in body weight and hepatosomatic index (HSI) of male mice. UPC2 -MS/MS analysis in both positive and negative mode, respectively, indicated significant differences between control and exposure groups in the liver of exposed mice. Principal component analysis (PCA) of the features revealed separation of control and exposure groups in both sexes. From the significantly differential 207 lipids, only 72 were identified and shown to belong to eight different lipid classes. PCA of fatty acids (FAs) profile showed a clear separation between control and PFAS exposure groups in both female and male mice, with differential abundant levels of 5 and 4 hydrolyzed FAs, respectively. Transcript and protein analysis of genes associated with lipid homeostasis (ppar-α and β, lxr-α and β, rxr, fasn and srebp) showed that PFAS exposure produced sex- and individual response related alterations. Glutathione reductase (Gr) activity showed exposure-related changes in both female and male mice, compared with controls. Overall, the present study has demonstrated changes in lipid metabolism after PFAS exposure, showing that PFAS accumulation in the liver resulted to hepatotoxic effects, potential interference with membrane lipid profile and homeostasis, and oxidative stress. Given the structural similarity with FAs, interaction between PFAS and nuclear receptors such as PPARs may have severe consequences for general health and physiology in exposed animals and humans.

EI/IOT of PFCs: Environmental impacts/interactions, occurrences, and toxicities of perfluorochemicals

Various studies have been conducted on the perfluorochemicals (PFCs) family over the years. These compounds have been sought in various industrial aspects involving the synthesis of everyday utilities due to their broad range of applications. As a result, PFCs have built up in the environment, causing concern. The presence of PFCs in various environmental media, such as terrestrial and marine settings, as well as the mechanisms of transport, bioaccumulation, and physio-chemical interactions of PFCs within plants, aquatic organisms, microplastics, and, ultimately, the human body, are discussed in this review, which draws on a variety of research publications. The interaction of PFCs with proteins, translocation, and adsorption by hydrophobic interactions were observed, and this had an impact on the natural functioning of biological processes, resulting in events such as phylogenic clustering, competitive inhibition, and many others, posing potential hazards to human health and other relevant organisms in the ecosystem. However, further research is needed to have a better knowledge of PFCs and their interactions so that low-cost treatments can be developed to eliminate them. It is therefore, future research should focus on the role of soil matrix as a defensive mechanism for PFCs, as well as the impact of PFC chain length rejection.

Adverse effects of polystyrene nanoplastic and its binary mixtures with nonylphenol on zebrafish nervous system: From oxidative stress to impaired neurotransmitter system

Micro(nano)plastics generally co-exist with other chemicals in the environment, resulting in inevitable interaction and combined toxic effects on biota. Nevertheless, little is known regarding the interaction of nanoplastics (NPs) with other co-occurring insults. Hereby, we investigated single and combined effects of chronic exposure (45 days) to polystyrene nanoplastic particulates (PS-NPs) and nonylphenol (4-NP) on zebrafish nervous system. Multiple biomarkers concerning with oxidative-stress [catalase (CAT) activity and reduced glutathione (GSH) level], cholinergic system [Acetylcholinesterase (AchE) activity], glutamatergic system [glutamine synthetase (GS) and glutamate dehydrogenase (GDH) activities], energy metabolism [a-ketoglutarate dehydrogenase (a-KGDH) activity], and histological alterations were assessed. Both single and binary exposure to PS-NPs and 4-NP induced oxidative stress through reducing CAT activity and GSH level, in which a more sever effect was noticed in combined exposure. The AchE activity was significantly inhibited only in single treatment groups demonstrating antagonistic interaction between PS-NPs and 4-NP. Effects on GS activity was also alleviated in binary exposure as compared with single exposure to each contaminant. In addition, an increase in GDH activity was noticed in PS-NPs at 10 and 100 μg/L, and simultaneous presence of PS-NPs and 4-NP with a greater response were observed in combined treatments. PS-NPs and 4-NP either in separate or binary mixtures disrupted energy metabolism by deficiency of α-KGDH activity; however, co-exposure to PS-NPs and 4-NP induced more intense adverse impacts on this parameter. Furthermore, histological analysis revealed that 4-NP and PS-NPs, alone or in combination, reduced neural cells. These findings provide new insight into the neurotoxic effects of binary exposure to PS-NPs and 4-NP at environmentally relevant concentrations. Overall, our findings raise concerns about the presence and toxicity of nano-scale plastic particulates and highlight the importance of investigating the interaction of Micro(nano)plastics with other environmental irritants.

Human serum poly- and perfluoroalkyl substance concentrations and their associations with gestational diabetes mellitus

Poly- and perfluoroalkyl substances (PFAS), which have been found in high concentrations in maternal serum, have the potential to impair glucose metabolism in pregnant women. However, the effects of PFAS exposure on the risk of gestational diabetes mellitus (GDM) remain inconsistent. In the current investigation, a case-control study involving 135 patients with GDM and 69 controls was conducted in Hangzhou, China. We determined the concentrations of 17 PFAS in maternal serum from each participant and elucidated the associations between those concentrations and the risk of GDM. Among the 17 PFAS, perfluorooctanesulfonate (median 7.53 and 7.44 ng/mL) was the predominant PFAS in both cases and controls, followed by perfluorooctanoic acid (PFOA; median 5.22 and 5.03 ng/mL) and 6:2 chlorinated perfluoroalkyl ether sulfonate (6:2 Cl-PFESA; median 2.58 and 2.42 ng/mL). Conditional logistic regression analysis showed that the maternal serum continuous levels of PFOA, perfluorononanoic acid (PFNA), perfluorohexanesulfonate (PFHxS), and 6:2 Cl-PFESA were significantly associated with the GDM risk, with adjusted odds ratios (ORs) of 1.84 (95% confidence interval (CI): 1.26, 3.51), 1.47 (1.17, 3.29), 1.33 (1.72, 3.48), and 1.34 (1.17, 2.53), respectively. In the adjusted model, the ORs of GDM for increasing tertiles of PFOA, PFNA, PFHxS, and 6:2 Cl-PFESA significantly increased. The adjusted ORs (95% CI) were 3.38 (2.16, 6.89), 2.61 (1.26, 5.40), 3.46 (1.64, 6.30), and 3.50 (1.62, 6.91) at the highest concentrations of PFOA, PFNA, PFHxS, and 6:2 Cl-PFESA, respectively. These results suggest that higher PFAS exposure, reflected in serum PFAS concentrations, was associated with GDM incidence in pregnant women.

Exposure and Health Risk Assessment of Per- and Polyfluoroalkyl Substances in Crayfish from the Middle and Lower Reaches of the Yangtze River

Per- and polyfluoroalkyl substances (PFASs) are a novel class of emerging persistent organic pollutants (POPs) owing to their environmental persistence and bioaccumulation. Red swamp crayfish is a major source of exposure to PFASs, while the dietary intake of PFASs from crayfish is still unclear. We investigated the concentrations of PFASs in 130 batches of crayfish and 100 environmental samples from Middle and Lower Reaches of the Yangtze River Delta. Seven Perfluoroalkyl carboxylic acids (PFCAs), 3 Perfluoroalkyl sulfonates (PFSAs), and 6:2 Cl-PFESA were analyzed by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Meanwhile, PFASs exposure levels were examined concretely in four tissues of crayfish and different circulation links. The average daily intake (ADI) risk model was used to evaluate the human health risk of consuming crayfish and suggested that the risk of PFASs exposure is at a low level.

Poly- and Perfluoroalkyl Substances (PFAS) in Landfills: Occurrence, Transformation and Treatment

Landfills have served as the final repository for > 50 % municipal solid wastes in the United States. Because of their widespread uses and persistence in the environment, per- and polyfluoroalkyl substances (PFAS) (>4000 on the global market) are ubiquitously present in everyday consumer, commercial and industrial products, and have been widely detected in both closed (tens ng/L) and active (thousands to ten thousands ng/L) landfills due to disposal of PFAS-containing materials. Along with the decomposition of wastes in-place, PFAS can be transformed and released from the wastes into leachate and landfill gas. Consequently, it is critical to understand the occurrence and transformation of PFAS in landfills and the effectiveness of landfills, as a disposal alternative, for long-term containment of PFAS. This article presents a state-of-the-art review on the occurrence and transformation of PFAS in landfills, and possible effect of PFAS on the integrity of modern liner systems. Based on the data published from 10 countries (250 + landfills), C4-C7 perfluoroalkyl carboxylic acids were found predominant in the untreated landfill leachate and neutral PFAS, primarily fluorotelomer alcohols, in landfill air. The effectiveness and limitations of the conventional leachate treatment technologies and emerging technologies were also evaluated to address PFAS released into the leachate. Among conventional technologies, reverse osmosis (RO) may achieve a high removal efficiency of 90-100 % based on full-scale data, which, however, is vulnerable to the organic fouling and requires additional disposal of the concentrate. Implications of these knowledge on PFAS management at landfills are discussed and major knowledge gaps are identified.

An Environmentally Relevant Mixture of Perfluorooctanesulfonic Acid and Perfluorohexanesulfonic Acid Does Not Conform to Additivity in Northern Leopard Frogs Exposed Through Metamorphosis

Per- and polyfluoroalkyl substances (PFAS) are chemicals associated with adverse health effects. At aqueous film-forming foam sites, they occur as mixtures, with perfluorooctanesulfonic acid (PFOS) and perfluorohexanesulfonic acid (PFHxS) commonly co-occurring in the highest concentrations. Although PFOS and PFHxS toxicities have been studied, few studies have tested their potential interaction. Using Rana pipiens, the present study compared toxicities of a 1:1 PFOS:PFHxS mixture to PFOS and PFHxS individually with the prediction that responses would be additive. Gosner stage 25 (GS 25) tadpoles were exposed through metamorphosis (GS 46) to 0.5 and 1 ppb PFOS or PFHxS alone or to a mixture of 0.5 ppb PFOS and 0.5 ppb PFHxS. Tadpoles were weighed and measured (snout-vent length [SVL]) at day 31, metamorphic climax (GS 42), and GS 46. These values were used to calculate the scaled mass index (SMI), a measure of body condition. Body burdens were quantified on day 31 and at GS 46. The PFOS and PFHxS body burdens were elevated relative to controls at GS 46. No effects were observed on survival, SVL, or mass. Single PFAS effects included a 17% reduction in SMI at day 31 (0.5 ppb PFHxS) and a 1.1-day longer metamorphic period (1 ppb PFHxS) relative to controls. Mixture results deviated from additivity-SMIs were higher than expected on day 31 and lower than expected at GS 42. In addition, time to GS 42 in the PFAS mixture exceeded expected additivity by 12 days. Results from a chronic exposure to a 1:1 PFOS:PFHxS mixture resulted in changes in body condition and length of metamorphosis that deviated from additivity. More PFAS mixture toxicity studies conducted at relevant ratios and concentrations are needed. Environ Toxicol Chem 2022;41:3007-3016. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Associations of single and multiple perfluoroalkyl substances exposure with folate among adolescents in NHANES 2007-2010

BACKGROUND

The accumulation of perfluoroalkyl substances (PFAS) in human body has raised concerns about the potential health impacts on children and adolescents. However, no study has evaluated the associations of PFAS exposure with folate concentrations among adolescents.

METHODS

In the present study, we mainly used three statistical approaches, namely multiple linear regression, Bayesian Kernel Machine Regression (BKMR), and quantile-based g-computation (Q-gcomp) models, to evaluate associations of individual PFAS and their mixtures with serum and red blood cell (RBC) folate concentrations in a sample of 721 adolescents from the NHANES 2007-2010.

RESULTS

In multiple linear regression models, for per unit increase in ln-transformed perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA) concentrations, RBC folate concentrations decreased by 72.4 (95% confidence interval (CI): -112.7, -32.2), 58.3 (95% CI: -115.0, -1.6), 60.7 (95% CI: -107.5, -13.8), and 76.5 (95% CI: -119.0, -33.9) nmol/L, respectively. A similar significant inverse association was also observed between ln-transformed PFDA and serum folate. BKMR models further confirmed inverse associations of serum PFOS and PFDA with RBC folate, and serum PFDA with serum folate. However, the inverse associations of PFOA and PFNA with RBC folate shown in multiple linear regression model were not observed or less evident in BKMR analyses. We observed interactions of PFOA with PFOS, PFNA, and PFDA on RBC folate in BKMR models, with the negative slopes for PFOS, PFNA, and PFDA increased when PFOA concentration increased from the 10th percentile to the 90th percentile. Both BKMR and Q-gcomp models suggested that the mixtures of five PFAS showed inverse overall associations with RBC folate concentration.

CONCLUSIONS

The present study revealed that adolescent exposure to PFAS might affect serum and RBC folate concentrations.

Toxicity assessment of historical aqueous film-forming foams (AFFFs) using cell-based assays

Aqueous film-forming foam (AFFF) has historically contained high concentrations of long-chain per-and polyfluoroalkyl substances (PFAS), which have been linked with adverse health outcomes. However, the toxicity of historical AFFFs remains largely unknown, presenting uncertainties in their risk assessment. This study assessed the toxicity of historical AFFFs by exposing human liver cells (HepG2) to various dilutions of 3M Light Water AFFF or Ansulite AFFF (0.001%, 0.002%, 0.005%, 0.009%, 0.019%, 0.038%, 0.075%, 0.15%, and 0.3%) for 24 h. The effects of the two AFFF formulations on the cell viability, intracellular reactive oxygen species (ROS) production, Nrf2-ARE activity, and DNA damage were assessed by CellTiter 96® Aq_ueous One Solution Cell Proliferation Assay (MTS kit), dichlorofluorescein diacetate assay, luciferase assay, and alkaline Comet assay, respectively. The results revealed that the two brands of AFFFs tested were toxic to HepG2 cells at dilutions lower than the recommended 3% application formulation. Specifically, exposure to 3M Light Water AFFF or Ansulite AFFF induced a dilution-dependent decrease in cell viability, increased intracellular ROS production, and increased Nrf2-ARE activity. However, except for the highest concentration (lowest dilution) of 3M Light Water AFFF tested (0.038%.), both 3M Light Water AFFF and Ansulite AFFF did not significantly induce cellular DNA damage. Overall, 3M Light Water AFFF was more toxic than Ansulite AFFF. The findings from this study provided valuable in vitro toxicity data that may better inform the health risk assessment of these historical AFFFs.

Effects of Polystyrene Microplastics on Human Kidney and Liver Cell Morphology, Cellular Proliferation, and Metabolism

Microplastics have gained much attention due to their prevalence and abundance in our everyday lives. They have been detected in household items such as sugar, salt, honey, seafood, tap water, water bottles, and food items wrapped in plastic. Once ingested, these tiny particles can travel to internal organs such as the kidney and liver and cause adverse effects on the cellular level. Here, human embryonic kidney (HEK 293) cells and human hepatocellular (Hep G2) liver cells were used to examine the potential toxicological effects of 1 μm polystyrene microplastics (PS-MPs). Exposing cells to PS-MPs caused a major reduction in cellular proliferation but no significant decrease in cell viability as determined by the trypan blue assay in both cell lines. Cell viability remained at least 94% for both cell lines even at the highest concentration of 100 μg/mL of PS-MPs. Phase-contrast imaging of both kidney and liver cells exposed to PS-MPs at 72 h showed significant morphological changes and uptake of PS-MP particles. Confocal fluorescent microscopy confirmed the uptake of 1 μm PS-MPs at 72 h for both cell lines. Additionally, flow cytometry experiments verified that more than 70% of cells internalized 1 μm PS-MPs after 48 h of exposure for both kidney and liver cells. Reactive oxygen species (ROS) studies revealed kidney and liver cells exposed to PS-MPs had increased levels of ROS at each concentration and for every time point tested. Furthermore, quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis at 24 and 72 h revealed that both HEK 293 and Hep G2 cells exposed to PS-MPs lowered the gene expression levels of the glycolytic enzyme, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and antioxidant enzymes superoxide dismutase 2 (SOD2) and catalase (CAT), thus reducing the potential of SOD2 and CAT to detoxify ROS. These adverse effects of PS-MPs on human kidney and liver cells suggest that ingesting microplastics may lead to toxicological problems on cell metabolism and cell-cell interactions. Because exposing human kidney and liver cells to microplastics results in morphological, metabolic, proliferative changes and cellular stress, these results indicate the potential undesirable effects of microplastics on human health.

Investigating the cytotoxic redox mechanism of PFOS within Hep G2 by hyperspectral-assisted scanning electrochemical microscopy

Perfluorooctane sulfonate (PFOS) is one of the most lethal per- and poly-fluoroalkyl substances (PFAS). Generally, exposure effects are studied through case-controlled studies, cohort studies, or cell assays. Unfortunately, most studies involving two-dimensional cell cultures require cell lysis or fixation. For in vitro studies, fluorescence microscopy has been useful, but methods to simultaneously discern phototoxic effects during an experiment are limited. Here, we use hepatocarcinoma (Hep G2) cells to examine the redox mechanism of PFOS cytotoxicity in vitro, while using hyperspectral-assisted scanning electrochemical microscopy (SECM) to differentiate between PFOS and redox mediator induced stress. Specifically, we correlate an increase in the electrochemical response of ferrocenemethanol oxidation with an increase in intracellular reactive oxygen species. Corresponding hyperspectral images of redox indicative-fluorophores implicate superoxide in the cytotoxic redox mechanism.

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

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

Perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA) modify in vitro mitogen- and antigen-induced human peripheral blood mononuclear cell (PBMC) responses

Environmental contaminants perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) are present in human serum at the highest concentration among all per- and polyfluoroalkyl substances (PFAS). Serum concentrations as high as 500 ng and 3000 ng PFOA/ml have been detected in individuals living near contamination sites and those occupationally exposed, respectively. Animal and human studies indicated that PFOA and PFOS at these serum concentrations perturb the immune system. The aim of this study was to examine the effects of in vitro exposure of human peripheral blood mononuclear cells (PBMC) to 1, 10, or 100 µM PFOA or PFOS in a medium with serum (RPMI-1640 + 5% human AB serum) on the measurement of proliferation, T cell activation, generation of memory T cells, and cytokine production/secretion. In addition, these immune system parameters were assessed for PBMC in a serum-free medium (OpSFM), which was stimulated with phytohemagglutinin (PHA) (2.5 µg/ml) or influenza vaccine antigen (0.625 µg/ml Flu Ag). PFOS decreased proliferation stimulated by PHA or Flu Ag. With Flu Ag stimulation, PFOA and PFOS inhibited the generation of memory T cells in a concentration-dependent manner. In OpSFM, PFOA and PFOS produced no marked change in proliferation and no inhibition of T cell activation. Cytokines measured in the media with Luminex methodology indicated decreased PBMC secretion of IFN-γ by PFOA and PFOS in medium with serum, but no alteration in OpSFM. The results indicated that changes in immune parameters due to PFOA or PFOS following Flu Ag stimulation are medium (±serum) dependent.

Epidemiology Evidence for Health Effects of 150 per- and Polyfluoroalkyl Substances: A Systematic Evidence Map

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) comprise a large class of chemicals with widespread use and persistence in the environment and in humans; however, most of the epidemiology research has focused on a small subset.

OBJECTIVES

The aim of this systematic evidence map (SEM) is to summarize the epidemiology evidence on approximately 150 lesser studied PFAS prioritized by the EPA for tiered toxicity testing, facilitating interpretation of those results as well as identification of priorities for risk assessment and data gaps for future research.

METHODS

The Populations, Exposure, Comparators, and Outcomes (PECO) criteria were intentionally broad to identify studies of any health effects in humans with information on associations with exposure to the identified PFAS. Systematic review methods were used to search for literature that was screened using machine-learning software and manual review. Studies meeting the PECO criteria underwent quantitative data extraction and evaluation for risk of bias and sensitivity using the Integrated Risk Information System approach.

RESULTS

193 epidemiology studies were identified, which included information on 15 of the PFAS of interest. The most commonly studied health effect categories were metabolic (n=37), endocrine (n=30), cardiovascular (30), female reproductive (n=27), developmental (n=26), immune (n=22), nervous (n=21), male reproductive (n=14), cancer (n=12), and urinary (n=11) effects. In study evaluation, 120 (62%) studies were considered High/Medium confidence for at least one outcome.

DISCUSSION

Most of the PFAS in this SEM have little to no epidemiology data available to inform evaluation of potential health effects. Although exposure to the 15 PFAS that had data was fairly low in most studies, these less-studied PFAS may be used as replacements for "legacy" PFAS, leading to potentially greater exposure. It is impractical to generate epidemiology evidence to fill the existing gaps for all potentially relevant PFAS. This SEM highlights some of the important research gaps that currently exist. https://doi.org/10.1289/EHP11185.

Perfluoroalkyl substance mixtures and cardio-metabolic outcomes in highly exposed male workers in the Veneto Region: A mixture-based approach

BACKGROUND

Perfluoroalkyl substances (PFAS) have been consistently associated with cardio-metabolic traits. Occupational exposures to multiple PFAS with health outcomes have been poorly investigated. The aim of the present study was to examine these associations among former workers involved in PFAS production.

METHODS

We considered 232 male ex-employees who had worked in a factory (Trissino, Veneto Region, Italy), which produced PFAS and other chemicals during 1968-2018. Out of twelve serum PFAS, only four (PFOA, PFOS, PFHxS, and PFNA) were quantifiable in at least 50% of samples. Non-fasting serum total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured. The associations between serum PFAS mixture and considered outcomes were assessed through linear regression mixed models and Weighted Quantile Sum (WQS) regression, adjusting for potential confounders.

RESULTS

PFOA was detected at the highest level, with a median concentration (in ng/mL) of 80.8 (min-max: 0.35-13,033), followed by PFOS (median: 8.55, min-max: 0.35-343), PFHxS (median: 6.8, min-max: 0.35-597) and PFNA (median: 0.8, min-max: 0.35-5). We observed that each A quartile increase in the WQS index was positively associated with the levels of TC (β: 8.41, 95% IC: 0.78-16.0), LDL-C (β: 8.02, 95% IC: 1-15.0) and SBP (β: 3.21, 95% IC: 0.82-5.60). No association of serum PFAS concentration on HDL cholesterol and DBP emerged. WQS analyses revealed a major contribution of PFNA and PFHxS for the cholesterol levels, although PFOA reported the highest concentration. PFOA and PFOS emerged as chemicals of concern regarding the association with SBP.

CONCLUSIONS

The results showed a clear association between serum PFAS levels and markers of cardiovascular risk and support the importance of clinical surveillance of cardiovascular risk factors in population with a high exposure to PFAS, especially in the occupational setting.

Per- and Polyfluoroalkyl Substances and Incident Hypertension in Multi-Racial/Ethnic Women: The Study of Women's Health Across the Nation

BACKGROUND

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are ubiquitous synthetic chemicals that may disrupt blood pressure controls; however, human evidence to support this hypothesis is scant. We examined the association between serum concentrations of PFAS and risks of developing hypertension.

METHODS

This study included 1058 midlife women initially free of hypertension from the multiracial and multiethnic SWAN (Study of Women's Health Across the Nation) with annual follow-up visits between 1999 and 2017. Hypertension was defined as blood pressure ≥140 mm Hg systolic or ≥90 mm Hg diastolic or receiving antihypertensive treatment. Cox proportional hazards models were utilized to calculate hazard ratios and 95% CIs. Quantile g-computation was implemented to evaluate the joint effect of PFAS mixtures.

RESULTS

During 11 722 person-years of follow-up, 470 participants developed incident hypertension (40.1 cases per 1000 person-years). Compared with the lowest tertile, women in the highest tertile of baseline serum concentrations had adjusted hazard ratios of 1.42 (95% CI, 1.19-1.68) for perfluorooctane sulfonate (P trend=0.01), 1.47 (95% CI, 1.24-1.75) for linear perfluorooctanoate (P trend=0.01), and 1.42 (95% CI, 1.19-1.70) for 2-(N-ethyl-perfluorooctane sulfonamido) acetate (P trend=0.01). No significant associations were observed for perfluorononanoate and perfluorohexane sulfonate. In the mixture analysis, women in the highest tertile of overall PFAS concentrations had a hazard ratio of 1.71 (95% CI, 1.15-2.54; P trend=0.008), compared with those in the lowest tertile.

CONCLUSIONS

Several PFAS showed positive associations with incident hypertension. These findings suggest that PFAS might be an underappreciated contributing factor to women's cardiovascular disease risk.

Comparative cytotoxicity of seven per- and polyfluoroalkyl substances (PFAS) in six human cell lines

Human exposures to perfluoroalkyl and polyfluoroalkyl substances (PFAS) have been linked to several diseases associated with adverse health outcomes. Animal studies have been conducted, though these may not be sufficient due to the inherent differences in metabolic processes between humans and rodents. Acquiring relevant data on the health effects of short-chain PFAS can be achieved through methods supported by in vitro human cell-based models. Specifically, cytotoxicity assays are the crucial first step to providing meaningful information used for determining safety and providing baseline information for further testing. To this end, we exposed human cell lines representative of six different tissue types, including colon (CaCo-2), liver (HepaRG), kidney (HEK293), brain (HMC-3), lung (MRC-5), and muscle (RMS-13) to five short-chain PFAS and two legacy PFAS. The exposure of the individual PFAS was assessed using a range of concentrations starting from a low concentration (10^-11 M) to a high concentration of (10^-4 M). Our results indicated that CaCo-2 and HEK293 cells were the least sensitive to PFAS exposure, while HMC-3, HepaRG, MRC-5, and RMS-13 demonstrated significant decreases in viability in a relatively narrow range (EC₅₀ ranging from 1 to 70 µM). The most sensitive cell line was the neural HMC-3 for all short- and long-chain PFAS (with EC₅₀ ranging from 1.34 to 2.73 µM). Our data suggest that PFAS do not exert toxicity on all cell types equally, and the cytotoxicity estimates we obtained varied from previously reported values. Overall, this study is novel because it uses human cell lines that have not been widely used to understand human health outcomes associated with PFAS exposure.

Ecotoxicological responses and removal of submerged macrophyte Hydrilla verticillate to multiple perfluoroalkyl acid (PFAA) pollutants in aquatic environments

The ubiquitous existence of perfluoroalkyl acids (PFAAs) in aquatic environments might pose toxic potential to ecosystems. To assess the ecotoxicological responses and removal of submerged macrophyte to multiple PFAA pollutants in aquatic environments, a typical submerged macrophyte, Hydrilla verticillate, was exposed to solutions with 12 typical PFAAs in the present study. The results showed that PFAAs at concentrations higher than 10 μg/L had significantly passive effects on biomass, relative growth rates, chlorophyll contents, and chlorophyll autofluorescence. PFAAs could induce the accumulation of hydrogen peroxide and lipid peroxidation in H. verticillate. Significant upregulation of CAT was observed in treatments with more than 10 μg/L PFAAs (p < 0.05). The results also showed that 13.53-20.01% and 19.73-37.72% of PFAAs could be removed in treatments without plants and with H. verticillate, respectively. The removal rates of PFAAs were significantly correlated with perfluoroalkyl chain length in treatments with H. verticillate. The removal of PFAAs was suggested to be related to the uptake of plant tissues and biosorption of microbiota. Furthermore, the dominant microbiota and biomarkers were identified in water and biofilm. Betaproteobacteriales was the most dominant microbiota at the order level. The presence of PFAAs could significantly increase the relative abundance of Micrococcales, Verrucomicrobiales, Rhizobiales, Sphingomonadales, Roseomonas, Cyanobium_PCC_6307, and Synechococcales. Our results provide scientific basis for evaluating the ecotoxicological responses and removal of submerged macrophytes in response to multiple PFAA pollutants at environmentally relevant levels, thereby providing insights into PFAA management and removal.

Antioxidant Responses Induced by PFAS Exposure in Freshwater Fish in the Veneto Region

In recent decades, the interest in PFAS has grown exponentially around the world, due to the toxic effects induced by these chemical compounds in humans, as well as in other animals and plants. However, current knowledge related to the antistress responses that organisms can express when exposed to these substances is still insufficient and, therefore, requires further investigation. The present study focuses on antioxidant responses in Squalius cephalus and Padogobius bonelli, exposed to significant levels of PFAS in an area of the Veneto Region subjected to a recent relevant pollution case. These two ubiquitous freshwater species were sampled in three rivers characterised by different concentrations of PFAS. Several biomarkers of oxidative stress were evaluated, and the results suggest that PFAS chronic exposure induces some physiological responses in the target species, at both cellular and tissue scales. The risk of oxidative stress seems to be kept under control by the antioxidant system by means of gene activation at the mitochondrial level. Moreover, the histological analysis suggests an interesting protective mechanism against damage to the protein component based on lipid vacuolisation.

Interactions between dissolved organic matter and perfluoroalkyl acids in natural rivers and lakes: A case study of the northwest of Taihu Lake Basin, China

Understanding the interactions between dissolved organic matter (DOM) and perfluoroalkyl acids (PFAAs) is essential for predicting the distribution, transport, and fate of PFAAs in aquatic environments. Based on field investigations in the northwest of Taihu Lake Basin combined with laboratory experiments, we obtained DOM and PFAA concentrations as well as compositions and investigated key factors of DOM affecting PFAA variability and capture of PFAAs by DOM. Results indicated that the total concentrations of PFAAs were 73.4-689 ng/L in surface water and that PFAAs were dominated by C3-7 perfluoroalkyl carboxylic acids and perfluorooctane sulfonic acid. The main components of DOM included tyrosine-, fulvic-, and tryptophan-like substances. The Mantel test revealed a significant positive correlation between DOM and PFAAs (P = 0.0001). Fulvic-like substances were identified as the most crucial factors affecting PFAA variability. The laboratory experiments revealed that DOM can spontaneously aggregate into a microgel. Furthermore, 19.1-50.9% of PFAAs, DOM characteristic peaks, and several metals (Ca, Mg, Cu, and Fe) can be removed during aggregation, indicating the capacity of DOM binding organic/inorganic substances. The fulvic-like substances were more effectively removed than the protein-like substances. The distribution coefficients of all PFAAs except perfluorohexanoic acid significantly correlated with their perfluorinated carbon numbers (r = 0.975, p<0.001). Our results provided insights into the interactions between DOM and PFAAs, improving the understanding of the distribution, transport, and fate of PFAAs in aquatic environments.

Select Per- and Polyfluoroalkyl Substances (PFAS) Induce Resistance to Carboplatin in Ovarian Cancer Cell Lines

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous environmental contaminants associated with adverse reproductive outcomes including reproductive cancers in women. PFAS can alter normal ovarian function, but the effects of PFAS on ovarian cancer progression and therapy response remain understudied. Ovarian cancer is the most lethal gynecologic malignancy, and a major barrier to effective treatment is resistance to platinum-based chemotherapy. Platinum resistance may arise from exposure to external stimuli such as environmental contaminants. This study evaluated PFAS and PFAS mixture exposures to two human ovarian cancer cell lines to evaluate the ability of PFAS exposure to affect survival fraction following treatment with carboplatin. This is the first study to demonstrate that, at sub-cytotoxic concentrations, select PFAS and PFAS mixtures increased survival fraction in ovarian cancer cells following carboplatin treatment, indicative of platinum resistance. A concomitant increase in mitochondrial membrane potential, measured by the JC-1 fluorescent probe, was observed in PFAS-exposed and PFAS + carboplatin-treated cells, suggesting a potential role for altered mitochondrial function that requires further investigation.

Single PFAS and PFAS mixtures affect nuclear receptor- and oxidative stress-related pathways in precision-cut liver slices of Atlantic cod (Gadus morhua)

The aim of the present study was to investigate effects of per- and polyfluoroalkyl substances (PFAS), both single compounds and a mixture of these, using precision-cut liver slices (PCLS) from Atlantic cod (Gadus morhua). PCLS were exposed for 48 h to perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA) and perfluorononanoate (PFNA) (10, 50 and 100 μM), and three mixtures of these at equimolar concentrations (10, 50 and 100 μM). Transcriptomic responses were assessed using RNA sequencing. Among exposures to single PFAS, PFOS produced the highest number of differentially expressed genes (DEGs) compared to PFOA and PFNA (86, 25 and 31 DEGs, respectively). Exposure to the PFAS mixtures resulted in a markedly higher number of DEGs (841). Clustering analysis revealed that the expression pattern of the PFAS mixtures were more similar to PFOS compared to PFOA and PFNA, suggesting that effects induced by the PFAS mixtures may largely be attributed to PFOS. Pathway analysis showed significant enrichment of pathways related to oxidative stress, cholesterol metabolism and nuclear receptors in PFOS-exposed PCLS. Fewer pathways were significantly enriched following PFOA and PFNA exposure alone. Significantly enriched pathways following mixture exposure included lipid biosynthesis, cancer-related pathways, nuclear receptor pathways and oxidative stress-related pathways such as ferroptosis. The expression of most of the genes within these pathways was increased following PFAS exposure. Analysis of non-additive effects in the 100 μM PFAS mixture highlighted genes involved in the antioxidant response and membrane transport, among others, and the majority of these genes had synergistic expression patterns in the mixture. Nevertheless, 90% of the DEGs following mixture exposure showed additive expression patterns, suggesting additivity to be the major mixture effect. In summary, PFAS exposure promoted effects on cellular processes involved in oxidative stress, nuclear receptor pathways and sterol metabolism in cod PCLS, with the strongest effects observed following PFAS mixture exposure.