Accumulation of perfluoroalkyl substances in human tissues

Per- and polyfluoroalkyl substances as potentiators of hepatotoxicity in an exposome framework: Current challenges of environmental toxicology

Chronic liver diseases, including metabolic dysfunction-associated steatosic liver disease (MASLD) and hepatocellular carcinoma (HCC), are on the rise, potentially due to daily exposure to complex mixtures of chemical compounds forming part of the exposome. Understanding the mechanisms involved in hepatotoxicity of these mixtures is essential to identify common molecular targets that may highlight potential interactions at the molecular level. We illustrated this issue with two families of environmental contaminants, per- and polyfluoroalkyl substances (PFAS) and heterocyclic aromatic amines (HAAs), both of which could be involved in the progression of chronic liver diseases, and whose toxicity may be potentiated by interactions at the level of xenobiotic metabolism. In the study of exposome effects on chronic liver disease, New Approach Methodologies (NAMs) including omics analyses and data from various in vitro, in vivo and in silico approaches, are crucial for improving predictivity of toxicological studies in humans while reducing animal experimentation. Additionally, the development of complex in vitro human liver cell models, such as organoids, is essential to avoid interspecies differences that minimize the risk for humans. All together, these approaches will contribute to construct Adverse Outcome Pathways (AOPs) and could be applied not only to PFAS mixtures but also to other chemical families, providing valuable insights into mixture hepatotoxicity prediction in the study of the exposome. A better understanding of toxicological mechanisms will clarify the role of environmental contaminant mixtures in the development of MASLD and HCC, supporting risk assessment for better treatment, monitoring and prevention strategies.

Neurotoxic effects of per- and polyfluoroalkyl substances (PFAS) mixture exposure in mice: Accumulations in brain and associated changes of behaviors, metabolome, and transcriptome

Humans are exposed to complex per- and polyfluoroalkyl substances (PFAS) mixtures, yet their neurotoxicity and mechanisms remains unclear. This study exposed male mice to 17 PFAS mixtures at low levels (0.2-20 µg/L) for 49 days via drinking water. Perfluoropentanoic acid (PFPeA), perfluoroheptanoic acid (PFHpA), 6:2 fluorotelomer sulfonic acid (6:2 FTS), and perfluorooctane Sulfonate (PFOS) accumulated in brain tissues, with brain/plasma ratios of 2.03-5.87, 2.94-12.88, 1.90-3.19, and 0.62-0.93, respectively. Electroencephalogram (EEG) results showed significant alterations, including a reduction in beta spectral edge (21.47-13.85 Hz) and an increase in gamma spectral edge (57.64-79.07 Hz). Histopathological analysis revealed necrosis in the hippocampus, contributing to the observed anxiety-like behaviors and memory impairments in exposed mice. Plasma metabolomics highlighted disrupted osmoprotectants, impaired glutamatergic synapse function, and tryptophan metabolism. Brain metabolomics demonstrated suppression of purine metabolism and activation of arachidonic acid metabolism, suggesting involvement in neurotoxic effects. Transcriptomic profiling further identified dysregulation in neuroactive ligand-receptor interactions, cholinergic and GABAergic synapses, and calcium signaling pathways, with oxytocin signaling highlighted as a critical mechanism. This study, for the first time, links PFAS mixture to neurotoxicity via neurotransmitter-related pathways, underscoring the need for public health policies and preventive strategies to mitigate PFAS exposure risks.

A machine learning multimodal profiling of Per- and Polyfluoroalkyls (PFAS) distribution across animal species organs via clustering and dimensionality reduction techniques

Per- and polyfluoroalkyl substances (PFAS) contamination in aquatic and terrestrial organisms poses significant environmental and health risks. This study quantified 15 PFAS compounds across various tissues (liver, kidney, gill, muscle, skin, lung, blood, breast, feather) from fish (Clarias gariepinus, Oreochromis niloticus, Lates niloticus, Tilapia zilli), livestock (camel, cow, sheep, ram, goat), and birds (pigeon, chicken, turkey). Among the fishes, C. gariepinus exhibited the highest PFAS accumulation, with PFOA (46.5 ng/g) and PFTrDA (50.1 ng/g) dominant in liver and kidney, while O. niloticus showed elevated PFTrDA (56.87 ng/g) and PFUnDA (29.43 ng/g). In livestock, camel liver contained high PFNA (9.22 ng/g), and cow liver had the highest PFOS (8.1 ng/g). Among the birds, pigeon liver showed the highest PFNA (7.83 ng/g). To analyze PFAS distribution patterns, dimensionality reduction and clustering techniques were employed. Principal Component Analysis (PCA) captured 68.28 % of total variance, revealing two distinct clusters whereby fish species are strongly related with higher PFAS concentration, while poultry showed unique PFAS profiles when compared to other types of meat. Clustering of PFOS, PFOA, and other PFAS compounds near the center explained their influence across the general meat types particularly the fish species, while t-Distributed Stochastic Neighbor Embedding (t-SNE) confirmed clear separations in high-dimensional space. Clustering analyses, including K-means, hierarchical clustering, DBSCAN, and Gaussian Mixture Models (GMM), identified well-defined patterns, with DBSCAN and GMM detecting overlapping categories and outliers. Feature importance analysis using a Random Forest model highlighted total PFAS as the most significant predictor, with PFHxA and PFDODA also contributing strongly, while organ type and species played a lesser role. These findings demonstrate the effectiveness of unsupervised learning techniques in characterizing PFAS bioaccumulation patterns across species and tissues, providing valuable information for ecological and toxicological risk assessments.

In vivo gamete toxicology in the context of in vitro fertilization: a narrative review

IVF as a clinical method to surmount infertility has existed since the 1970s, and yet fertilization, embryo development, pregnancy, and live birth rates remain unacceptably low. Although a multitude of factors may contribute to stagnated success despite substantial advances in basic and applied IVF sciences, gamete quality is inarguably integral to IVF success rates. In this review, the authors will explore the role of environmental toxicology in impairing in vivo fertility and gamete quality prior to starting IVF that will influence downstream IVF success. In vivo contaminants of interest that may affect gamete potential in the context of IVF include heavy metals, per- and polyfluoroalkyl substances (PFAS), persistent organic pollutants (POPs), and airborne contaminants. By evaluating the current literature on reproductive toxicology and how toxic exposures may influence IVF, this review aims to provide a comprehensive reference of potential toxicological exposures for clinicians, to use in vitro and animal data to supplement correlative human studies with potential causative mechanisms, and to strengthen the case for patient assessment of toxicological risk.

Characterization of POP mixture redistribution and identification of their molecular signature in xenografted fat mice

Persistent organic pollutants (POPs) are associated with many adverse health effects in humans, including cancers, immune, reproductive, neurological disorders and metabolic diseases. These chemicals are known to accumulate in fatty tissues, from which they can be released in other tissue compartments of living organisms, in particular, upon weight loss. This dynamic distribution of POPs remains, however poorly investigated. In this study, a xenografted POP-contaminated adipose tissue (AT) model was used to assess 1) their concentrations in the ATs, the liver and the brain and 2) their associated effects by transcriptomics, metabolomics and lipidomics approaches. In the ATs, the liver and the brain of mice grafted with POP-contaminated fat pad, most of POPs were detected 3 days and 21 days after the graft with the highest concentrations in the ATs and the lowest concentrations in the brain. Conversely, per- and polyfluoroalkyl substances presented a distinct profile as they persist in the liver but not in the ATs or in the brain. In the AT of POP-exposed mice, the most dysregulated pathways were related to mitochondrial functions, endobiotic (carbohydrate, lipid, amino acid) and xenobiotic metabolism and inflammatory response. In the liver of grafted mice, many pathways related to mitochondrial functions and metabolism were dysregulated. These results support that realistic mixture of POPs that accumulate in AT and liver induces a systemic metabolic dysfunction which may represent the mechanisms by which the POPs can promote metabolic diseases such as obesity, type 2 diabetes and cardiovascular diseases.

Integrated PBPK Modelling for PFOA Exposure and Risk Assessment

Per- and polyfluoroalkyl substances (PFASs) pose significant public health concerns due to their environmental persistence, bioaccumulation, and ubiquitous presence in human biomonitoring (HBM) data, despite regulatory restrictions. This study establishes a deterministic pharmacokinetic model for perfluorooctanoic acid (PFOA), enabling the estimation of PFOA concentrations in major human organs, even at low doses. The model integrates accumulation and recirculation mechanisms of PFOA in hepatic and renal tissues, leveraging publicly available HBM datasets (e.g., HBM4EU, NHANES, literature) to reconstruct bodyweight-normalized intake levels. Importantly, due to the extremely low urinary excretion concentrations of PFOA, most datasets were derived from blood-based measurements, particularly serum while confirming urine as unreliable biomarker of exposure. The analysis underscores the effectiveness of regulatory efforts in reducing PFOA exposures, as evidenced by declining time-trends in estimated exposure levels in recent studies. Risk characterization ratios were calculated based on recommended limits set by the European Food Safety Authority (EFSA), the United States, and Australia. While EFSA's tolerable weekly intake (TWI) indicated a high risk, other regulatory limits suggested less concern about risk at these intake levels. These findings highlight the need for continuous re-evaluation of exposures and targeted studies to identify key determinants of PFOA exposure, informing future regulatory measures. The study emphasizes the critical role of physiologically based pharmacokinetic (PBPK) modeling, HBM data, and exposure reconstruction in advancing chemical risk assessment. These tools form a science-based framework integral to the Chemical Strategy for Sustainability (CSS), enabling accurate predictions of internal exposure levels, empirical validation of models, and robust assessments of real-world exposure scenarios. The integration of these approaches supports the CSS goals of minimizing chemical risks while promoting innovation, ultimately contributing to a sustainable and protective regulatory landscape for human health and the environment.

Screening for endocrine-disrupting chemicals in the serum and cerebrospinal fluid of patients with autoimmune encephalitis

Humans are exposed to a variety of endocrine-disrupting chemicals (EDCs), such as organophosphate esters (OPEs) and phthalate ester (PAE) metabolites. Although EDCs can cross the blood-cerebrospinal fluid barrier (BCSFB) to the brain, their effects on autoimmune encephalitis (AE) remain unclear. Therefore, the association between EDC exposure and AE were determined. The study recruited 106 patients with AE and 119 patients without AE. Using paired serum-CSF samples, we quantified 8 categories of 17 EDCs. The penetration of some EDCs was evaluated through two indices: calculated the blood-brain barrier (BBB) index and the paired serum-CSF concentration ratio. Further, we investigated the association of EDC exposure with AE by the conditional logistic regression analysis. Antioxidants, PAE metabolites, and OPEs were identified as the most dominant EDC in the ∑8 categories of EDCs. The median EDC ratios (REDC = EDCCSF/EDCSerum) ranged from 0.040 % for methyl paraben (MeP) to 3.808 % for ethyl paraben (EtP). AE patients are more likely to have BBB disruption. The associations between AE and some EDCs were found. For example, serum EtP and butyl paraben (BuP) levels [Odds Ratio (OR) = 1.69; 95 % confidence interval (CI): 1.25, 2.27; OR = 1.51; 95 % CI: 1.14, 2.00), and CSF MeP levels (OR =1.54; 95 % CI: 1.30, 1.84) were both associated with an increased risk of AE. We identified that exposure to certain environmental EDCs may be a risk factor for the development of AE. Our findings support an evidence base for the effects of specific chemicals may impair neural functions.

PFHxA and PFHxS promote breast cancer progression in 3D culture: MEX3C-associated immune infiltration revealed by bioinformatics and machine learning

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants with widespread use and bioaccumulative potential. Short-chain PFAS such as perfluorohexanoic acid (PFHxA) and perfluorohexane sulfonate (PFHxS) have been introduced as safer alternatives to long-chain PFAS, yet their toxicological impacts remain poorly defined. In this study, we employed a 3D Gelatin methacryloyl (GelMA) hydrogel model to mimic the tumor microenvironment and investigated the effects of PFHxA and PFHxS on triple-negative breast cancer (TNBC) progression. At environmentally relevant concentrations (0.1-10 μM), both compounds significantly enhanced proliferation, migration, and invasion of MDA-MB-231 cells. Transcriptomic and machine learning analyses identified MEX3C as a key gene upregulated by PFAS exposure. Gene set enrichment analysis (GSEA) revealed activation of the PI3K-AKT-mTOR signaling pathway, which was further supported by siRNA-mediated knockdown of MEX3C, leading to a marked reduction in the expression levels of phosphorylated PI3K, AKT, and mTOR proteins. Furthermore, immune cell co-culture experiments showed that MDA-MB-231 cells with high MEX3C expression promoted M2 macrophage polarization, suppressed M1 polarization, and enhanced macrophage chemotactic activity, the immunomodulatory effects were significantly attenuated upon MEX3C knockdown. These findings establish MEX3C as a central mediator of PFAS-induced tumor progression and immune remodeling. This study provides mechanistic insight into the carcinogenic potential of emerging short-chain PFAS and underscores the need for stricter regulation to safeguard public health.

Perfluorooctanoic acid increases serum cholesterol in a PPARα-dependent manner in female mice

Per- and polyfluoroalkyl substances (PFAS) are a large group of persistent chemicals that are pervasive in the environment leading to widespread exposure for humans. Perfluorooctanoic acid (PFOA), one of the most commonly measured PFAS in people, disrupts liver and serum lipid homeostasis as shown in animal toxicity and human epidemiological studies. We tested the hypothesis that the effects of PFOA exposure in mice expressing mouse PPARα (mPPARα) are driven largely through PPARα-dependent mechanisms while non-PPARα dependent mechanisms will be more apparent in mice expressing human PPARα (hPPARα). Female and male mPPARα, hPPARα, and PPARα null mice were exposed to PFOA (0.5, 1.4 or 6.2 mg PFOA/L) via drinking water for 14 weeks. Concurrently, mice consumed an American diet containing human diet-relevant amounts of fat and cholesterol. Here, we focused on the effects in female mice, given the dearth of data reported on PFAS-induced effects in females. Increasing the duration of PFOA exposure reduced weight gain in all genotypes of female mice while end-of-study body fat was lower in PFOA exposed hPPARα and PPARα null mice. Serum cholesterol, but not triacylglyceride, concentrations were increased by PFOA exposure in a PPARα-dependent manner. Hepatic triacylglycerides were higher in vehicle-exposed mPPARα and PPARα null mice than hPPARα mice, and PFOA significantly reduced concentrations in mPPARα and PPARα null mice only. In contrast, PFOA increased hepatic cholesterol content in a PPARα-dependent manner. Changes in liver and serum cholesterol may be explained by a strong, PPARα-dependent downregulation of Cyp7a1 expression. PFOA significantly increased PPARα target gene expression in mPPARα mice. Other nuclear receptors were examined: CAR target gene expression was only induced by PFOA in hPPARα and PPARα null mice. PXR target gene expression was induced by PFOA in all genotypes. Results were similar in male mice with two exceptions: (1) vehicle-exposed male mice of all genotypes were equally susceptible to diet-induced hepatic steatosis; (2) male mice drank less water, resulting in lower serum PFOA levels, which may explain the less significant changes in lipid endpoints. Overall, our results show that PFOA modifies triacylglyceride and cholesterol homeostasis independently and that PPARα plays an important role in PFOA-induced increases in liver and serum cholesterol.

Associations between per-and polyfluoroalkyl substances (PFAS) and county-level cancer incidence between 2016 and 2021 and incident cancer burden attributable to PFAS in drinking water in the United States

BACKGROUND

Exposure to per- and polyfluoroalkyl substances (PFAS) has been linked with various cancers. Assessment of PFAS in drinking water and cancers can help inform biomonitoring and prevention efforts.

OBJECTIVE

To screen for incident cancer (2016-2021) and assess associations with PFAS contamination in drinking water in the US.

METHODS

We obtained county-level age-adjusted cancer incidence (2016-2021) from the Surveillance, Epidemiology, and End Results (SEER) Program. Data on PFAS levels in public drinking water systems were obtained from the Third (UCMR3; 2013-2015) and Fifth (UCMR5; 2023-2024) Unregulated Contaminant Monitoring Rule. UCMR3 measured PFOS, PFOA, PFNA, PFHxS, PFHpA, and PFBS. UCMR5 expanded measurements to include PFBA, PFHxA, PFPeA, and PFPeS. We created indicators of PFAS detection and, for UCMR5, concentrations above Maximum Contaminant Levels (MCLs). MCLs for PFOA and PFOS are 4 ng/L, and for PFNA and PFHxS are 10 ng/L. We used Poisson regression models to assess associations between PFAS detection or MCL violation and cancer incidence, adjusting for potential confounders. We estimated the number of attributable cancer cases.

RESULTS

PFAS in drinking water was associated with increased cancer incidence in the digestive, endocrine, oral cavity/pharynx, and respiratory systems. Incidence rate ratios (IRRs) ranged from 1.02 to 1.33. The strongest association was observed between PFBS and oral cavity/pharynx cancers (IRR: 1.33 [1.04, 1.71]). Among males, PFAS was associated with cancers in the urinary, brain, leukemia, and soft tissues. Among females, PFAS was associated with cancers in the thyroid, oral cavity/pharynx, and soft tissue. PFAS in drinking water is estimated to contribute to 4626 [95% CI: 1,377, 8046] incident cancer cases per year based on UCMR3 data and 6864 [95% CI: 991, 12,804] based on UCMR5.

IMPACT STATEMENT

The ecological study examined the associations between PFAS in drinking water measured in two waves (2013-2015 and 2023-2024) and cancer incidence between 2016 and 2021. We found that PFAS in drinking water was associated with cancers in the organ system including the oral cavity/pharynx, lung, digestive system, brain, urinary system, soft tissue, and thyroid. Some cancers have not been widely studied for their associations with PFAS. We also observed sex differences in the associations between PFAS and cancer risks. This is the first ecological study that examined PFAS exposure in drinking water and various cancer risks.

The role of per- and polyfluoroalkyl substances in cognitive impairment and dementia

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous persistent organic pollutants. The neurotoxic and cardiometabolic effects of PFAS are well documented, leading to the hypothesis that exposure increases dementia risk. However, empirical data on PFAS in relation to cognitive impairment and dementia are weak, limited, and inconsistent. This report reviews the literature on PFAS and cognitive impairment and provides a rationale and overview of the PFAS VascCog Longitudinal Study, a new study using the population-based Northern Manhattan Study cohort, to prospectively examine serum concentrations of 13 PFAS in relation to lipids, carotid atherosclerosis, cognitive impairment, and dementia. We hypothesize that PFAS deleteriously impact cognition through a pathway involving hyperlipidemia and atherosclerosis. Rigorous examination of PFAS exposure in relation to dementia is needed to inform public health policies on PFAS-containing products, support regulations to reduce community exposure, and provide new avenues to protect cognitive health and impact dementia at the individual and community levels. HIGHLIGHTS: PFAS exposure increases cardiometabolic risk factors and neurotoxicity. Data on PFAS in relation to cognitive health is limited, weak, and controversial. We hypothesize that PFAS exposure increases dementia risk. We hypothesize a mechanistic pathway involving hyperlipidemia and atherosclerosis. Rigorous study of PFAS exposure and dementia risk can inform public health policy.

A review of the occurrence and distribution of Per- and polyfluoroalkyl substances (PFAS) in human organs and fetal tissues

This review synthesizes current evidence on PFAS concentrations across human organs and tissues, excluding blood matrices. Literature search was conducted using PubMed, Web of Science, and Scopus. The earliest reported study on the topic measured PFOS, PFOSA, PFOA, and PFHxS levels in human liver and serum, showing mean liver concentrations of 18.8 ng/g and a liver-to-serum ratio of 1.3:1 for PFOS. Subsequent research extended these findings to other organs, with measurements in pooled samples indicating organ-specific accumulation patterns. PFOS was predominant in liver, kidney, and lung, while PFOA was more prominent in bone. Pathological conditions, such as liver disease, have shown to influence PFAS distribution, with diseased tissues exhibiting altered accumulation patterns. On the other hand, the occurrence of PFAS in fetal and placental tissues demonstrated that these compounds cross the placenta, although fetal exposure levels were significantly lower than maternal levels. Tissue-specific accumulation has been reported, with liver and lung showing higher concentrations compared to other fetal tissues. Associations between PFAS levels in the placenta and birth outcomes indicated potential sex-specific effects, including reduced birth weight in male infants exposed to higher PFOS levels. This review highlights important differences in the detection frequencies and concentrations of PFAS across organs and the specific studies. These variations are attributed to differences in analytical methods, sample characteristics, and exposure sources. The findings underscore the need for standardized methodologies and further research to better understand PFAS distribution in human tissues and their potential health impacts, particularly during critical developmental stages.

Exposure-effect of PFOS and PFOA on lung function: An integrated approach with epidemiological, cellular, and animal studies

Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are increasingly recognized for their adverse impact on human health, particularly on lung function. However, current research results are inconsistent and molecular mechanisms remain unclear, with no studies combining epidemiological, in vivo and in vitro investigations. Our population-based study revealed that PFOS and PFOA exposure is negatively associated with lung function. In vitro, PFOS and PFOA exposure significantly downregulated SP-B mRNA and protein levels, and SP-B expression was restored by overexpression of HSD17B1. PFOS induced hypermethylation and downregulated expression of HSD17B1 in tandem with SP-B. Notably, expression of SP-B was restored after treatment with demethyltransferase inhibitor. In vivo studies corroborated these findings, where PFOS exposure resulted in impaired lung function, histopathological changes, and decreased expression of SP-B and HSD17B1 in lung tissues. Our research demonstrates that PFOS downregulates SP-B expression by inducing hypermethylation and downregulating expression of HSD17B1, leading to impaired lung function.

Exposure to PFOS, PFBS, PFOA and PFBA impairs cell cycle progression in bovine brain (Bos taurus) endothelial cells

Perfluoroalkylated substances (PFAS) are the large class of synthetic chemicals that persist in the environment and bioaccumulate in different tissues including the brain, inducing blood brain barrier (BBB) disruption. In this study, we assessed cytotoxicity of PFAS in a bovine brain endothelial cell line by exposing the cells to increasing concentrations (0.01, 0.1, 1, 10, and 100 μM) of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorobutane sulfonic acid (PFBS), perfluorobutanoic acid (PFBA) and perfluoro ([5-methoxy-1,3-dioxolan-4-yl]oxy) acetic acid (C6O4). Cell viability, cell cycle profiling and the apoptotic potential were then analyzed. Cells were categorized by grouping nuclei into G0 + G1, Synthesis (S) and Mitotic phases (M), nuclei showing characteristics of senescence and nuclear fragments. By combining high throughput screening with cell nuclei counting for group, we determined the relationship between the dose-response effect of PFAS and their proliferative potential. Our results showed that PFOS decreased the number of cells in S and M phase. PFBS reduced the number of cells in M phase, decreased the senescence phenotype and increased the number of fragment nuclei. PFOA enhanced the number of cells nuclei in S and M phase. The PFBA enhanced the number of nuclei in G0 + G1, S and M phase. C6O4 did not show significant variation under any of the experimental conditions tested. We did not find significant changes in terms of cell viability assay. This bovine endothelial cell line provides an alternative model for studying the mechanisms involved in the decrease of BBB integrity due to PFAS accumulation in a large mammal with large brain.

Distribution of perfluorooctanoic acid in exposed female postpubertal pigs in thermal neutral or heat-stressed conditions

Perfluorooctanoic acid (PFOA), a legacy perfluoroalkyl substance with immuno- and repro-toxicant effects, has poorly characterized bioaccumulation and distribution patterns in postpubertal female pigs. The potential for heat stress (HS) to influence PFOA partitioning, potentially through intestinal hyperpermeability and alterations in systemic blood flow, also warrants investigation. This study investigated PFOA uptake, accumulation, and distribution in thermal neutral (TN) and heat-stressed gilts. Pigs (n = 48) were estrus synchronized and experienced TN (20 °C) or HS (26.6 to 32.2 °C) conditions during which they consumed 70 ng/kg bodyweight PFOA via cookie dough as vehicle control daily. Plasma was collected on d 1, 15, and 20. Liver, ovary, and follicular fluid were collected at euthanasia (d 20). Post-exposure, PFOA was detected in serum, liver, ovary, and follicular fluid. HS increased (P < 0.05) plasma PFOA compared with TN pigs on d 15, but on d 20, plasma PFOA levels in TN and HS pigs were similar. Liver PFOA concentrations were similar between TN and HS pigs. Ovarian PFOA levels tended (P = 0.06) to be higher in TN relative to HS pigs, with an opposing pattern in follicular fluid, in which PFOA concentrations were greater (P < 0.05) in HS pigs. These findings suggest that PFOA apportions to plasma, liver, ovary, and follicular fluid of exposed pigs and that HS alters PFOA distribution, which could negatively impact reproductive health. This study underscores the need to consider the interaction of HS and toxicant exposure in environmental health risk assessments.

Exposure to per- and poly-fluoroalkyl substances and hematological cancer: A systematic review and meta-analysis

Recent literature suggests that exposure to per- and polyfluoroalkyl substances (PFAS) may be associated with increased cancer risk. However, evidence regarding their association with hematological cancers is inconclusive. Hence, we aimed to summarize findings of epidemiological studies on the issue. We conducted a systematic review by searching Pubmed and Scopus in April 2025 to identify studies on the association between PFAS and cancer types other than liver, kidney, and testis. We pooled relative risks (RRs) and 95 % confidence intervals (CIs) for the association between PFAS exposure and hematological cancers with restricted maximum likelihood method. Fourteen studies were included in the review. We found pooled RRs of 1.04 (95 % CI: 0.98, 1.10; I2=12.0 %, phet=0.332), 1.04 (95 % CI: 0.95, 1.14; I2=0.0 %, phet=0.523), and 1.06 (95 % CI: 0.94, 1.19; I2=42.9 %, phet=0.105) for the association between environmental or occupational PFAS exposure and total hematological cancer, leukemia, and lymphoma, respectively. As for types of lymphoma, environmental or occupational PFAS exposure was associated with incidence of non-Hodgkin lymphoma (RR: 1.15; 95 % CI: 1.01, 1.29; I2=0.0 %, phet=0.579), while no association with its mortality or with Hodgkin lymphoma was observed. The RR for the association between high serum levels of perfluorooctanoic acid and total hematological cancer was 1.13 (95 % CI: 0.72, 1.75; I2=64.6 %%, phet=0.023). Our results are suggestive of an association between PFAS exposure and non-Hodgkin lymphoma. Weak associations were also observed for total hematological cancer and leukemia among male individuals. Due to potential exposure misclassification in included studies, further evidence is needed to confirm our findings.

Bioaccumulation, Biotransformation and Oxidative Stress of 6:2 Fluorotelomer Sulfonamidoalkyl Betaine (6:2 FTAB) in Earthworms (Eisenia fetida)

As a novel perfluorooctane sulfonate (PFOS) alternative, 6:2 fluorotelomer sulfonamide alkylbetaine (6: 2 FTAB) has been detected in the environment and biotas. However, its behaviors and toxicity in earthworms remain unclear. Here, earthworms (Eisenia fetida) were exposed to 6:2 FTAB to investigate its bioaccumulation, biotransformation and toxicity. Results indicated that 6:2 FTAB could be biodegraded in soil into perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), perfluorobutanoic acid (PFBA) and perfluoropropionic acid (PFPrA). The uptake rate constant (ku) and the bioaccumulation factor (BAF) of 6:2 FTAB in earthworms were 0.0504 goc gww-1 d and 1.65 goc gww-1, respectively. 6:2 FTAB was biotransformed to form PFHxA, PFPeA, PFBA and PFPrA in earthworms after in vivo and in vitro exposure. The aerobic bacteria isolated from worm gut could degrade 6:2 FTAB to form PFPeA and PFHxA, while the anaerobic bacteria did not contribute to 6:2 FTAB biodegradation in worms. Peroxidase (POD) and superoxide dismutase (SOD) activities were significantly increased, while no significant changes were observed for catalase (CAT) activities, demonstrating activation of the primary antioxidant defense system against oxidative stress in earthworms after exposure to 6:2 FTAB. The significant increase of glutathione-S-transferase (GST) activities suggested indirect evidence on the conjugation of 6:2 FTAB or its metabolites in phase II of detoxication. This study provides important information on the fate of 6:2 FTAB in earthworms.

Three-Dimensional Cultured Human Nasal Epithelial Cell Model for Testing Respiratory Toxicity and Neurotoxicity of Air Pollutants

Accumulating evidence suggests a strong correlation between air pollution and neurological disorders; however, appropriate models and methodologies are currently lacking. In this study, a human nasal RPMI 2650 cell model based on air-liquid interface culture was discovered to possess olfactory epithelial cells. Two short-chain per- and polyfluoroalkyl substances (PFAS), PFBA and PFHxA, were used to validate the performance of the model. RNA sequencing initially revealed the adverse effects of two PFAS at environmentally relevant concentrations. Their effects on key nasal epithelial cell functions, including barrier protection, solute transport, and neuronal activity, were separately investigated. Both PFBA and PFHxA disrupted membrane integrity and increased cellular transport capacity, as indicated by the upregulation of ABC transporters. Additionally, they inhibited tight junction proteins, including ZO-1, claudin-3, and occludin, while increasing mucin expression and mucus secretion. PFHxA exhibited stronger effects in most assays and uniquely induced a significant upregulation of NOTCH1 expression (p < 0.05), highlighting its potential hazards on olfactory neurons. This study proposed a novel in vitro test model with the matched respiratory epithelial and neuronal end points, which was expected to improve toxicological research and risk assessment of air pollutants.

Serum concentrations of per- and poly-fluoroalkyl substances (PFAS) in Danish pregnant women-temporal trends during pregnancy, correlations with partners, associations with physical activity, and blood lipid concentrations

BACKGROUND

Per- and polyflouralkyl substances (PFAS) are a group of persistent chemicals used extensively in industries and consumer products due to their water-repellent properties. Studies have linked PFAS exposure to adverse health effects, and human exposure to PFAS, especially during pregnancy, is of great concern. In this study, we report how serum PFAS concentrations during pregnancy correlated with serum PFAS of partners from the same household. Further, we report how serum PFAS concentrations change during the course of pregnancy and associations between PFAS and blood lipid concentrations as well as exploratory analyses of associations between physical activity and PFAS concentrations.

METHODS

In this secondary analysis of data from the FitMum study conducted from 2018 to 2021, 216 healthy, pregnant women, and 110 of their partners were included. Non-fasting venous blood samples were collected from the mothers at three test visits during pregnancy and at delivery, where blood from partners were also collected. Serum samples from all timepoints were analyzed for 15 short- and long-chained PFAS using liquid chromatography triple quadrupole linear ion trap mass spectrometry. Total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglyceride blood concentrations were measured at three test visits during pregnancy and at delivery. Physical activity was measured with a wrist-worn activity tracker 24/7 from inclusion before gestational age week 15 + 0 and throughout pregnancy.

RESULTS

In serum samples we detected the following PFAS: PFOS, PFOA, PFHxS, PFNA, PFDA, and PFUnDA. The maternal median concentrations at baseline were: PFOS: 4.09 ng/mL, PFOA: 0.81 ng/mL, PFHxS: 0.29 ng/mL, PFNA: 0.42 ng/mL, PFDA: 0.25 ng/mL, and PFUnDA: 0.19 ng/mL. Partner serum PFAS concentrations were 3-145% higher than maternal concentration (except for PFUnDA). PFAS concentrations correlated within couples. All PFAS decreased significantly during pregnancy (PFOS -23.1 percent 95%-CI [-31.9;-13.2] from baseline to delivery). All PFAS concentrations were associated with increased HDL-C concentrations. No associations between physical activity and maternal PFAS concentrations were found.

CONCLUSIONS

Overall, serum PFAS concentrations decreased during pregnancy. PFAS concentrations within households were strongly correlated. PFAS and HDL-C concentrations were positively associated. We found no associations between physical activity and serum PFAS concentrations.

TRIAL REGISTRATION

The study was registered at ClinicalTrials.gov; NCT03679130; 20/09/2018.

Associations between per- and polyfluoroalkyl chemicals and abdominal aortic calcification in middle-aged and older adults

INTRODUCTION

Per- and polyfluoroalkyl substances (PFAS) have infiltrated countless everyday products, raising concerns about potential effects on human health, specifically on the cardiovascular system and the development of abdominal aortic calcification (AAC). However, our understanding of this relationship is still limited.

OBJECTIVES

This study aims to investigate the effects of PFAS on AAC using machine learning algorithms.

METHODS

Leveraging the power of machine learning technique, extreme gradient boosting (XGBoost), we assessed the relationship between PFAS exposure and AAC risk. We focused on three PFAS compounds, perfluorodecanoic acid (PFDeA), perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA) through multiple logistic regression, restricted cubic spline (RCS), and quantile g-computation (QGC) models. To get more insight into the underlying mechanisms, mediation analyses are used to investigate the potential mediating role of fatty acids and blood cell fractions in AAC.

RESULTS

Our findings indicate that elevated serum levels of PFHxS and PFDeA are associated with the increased risk of AAC. The QGC analyses underscore the overall positive association between the PFAS mixture and AAC risk, with PFHxS carrying the greatest weight, followed by PFDeA. The RCS analyses reveal a dose-dependent increase between serum PFHxS concentration and AAC risk in an inverted V-shape way. Moreover, age and PFHxS exposure are identified as the primary factors contributing to abdominal aortic calcification risk in SHapley Additive exPlanation (SHAP) summary plot combined with XGBoost technique. Although PFAS significantly change the profile of fatty acids, we do not find any mediating roles of them in AAC. Despite strong associations between PFAS exposure and hematological indicators, our analysis does not find evidence that these indicators mediate the development of AAC.

CONCLUSIONS

In summary, our study highlights the detrimental impact of PFAS on abdominal aortic health and emphasizes the need for further research to understand the underlying mechanisms involved.

Association of perfluoroalkyl substance (PFAS) on vitamin D biomarkers in a highly exposed population of the Veneto Region in Italy

Perfluoroalkyl substances (PFASs) raise concerns about their environmental accumulation. Experimental data have suggested that PFASs interfere with bone metabolism from the early stages of life. However, mechanisms underlying this association are unclear. The aim of this study was to evaluate the possible association between environmental exposure to PFAS and vitamin D (VitD), serum calcium and parathyroid hormone (PTH) levels in subjects residing in high-exposure area of the Veneto Region of Italy. In this cross-sectional observational study, 1174 subjects who previously adhered to the 2016-2018 Regional Surveillance Plan for plasma levels of PFASs were recalled in 2023 and evaluated for demographic, anthropometrics and blood analyses. Data on nutritional habits and VitD supplementation were obtained by a dedicated questionnaire. Serum concentrations of PFASs, calcium, 25-hydroxy-vitamin D (25OH-VitD) and PTH were determined from blood sampling. Perfluorooctanoic acid (PFOA), perfluorooctanesulfonate (PFOS) and perfluorohexanesulfonic acid (PFHxS) were the only three PFASs, of 12, quantifiable in at least 90% of the samples and considered for further analyses. Generalized additive models, using linear regression and smoothing thin plate splines, detected a positive association between serum calcium and all considered PFAS (PFOA: β = 0.03; CI 95% 0.01-0.06; PFOS: β = 0.06; CI 95% 0.02-0.09, PFHxS: β = 0.04; CI 95% 0.01-0.06). Estimated degrees of freedom (EDF) analysis showed the approximately linear association between serum calcium with PFOA (EDF = 1.89) and PFHxS (EDF = 1.21), but not for PFOS (EDF = 3.69). Differently, PFAS levels showed no association with either 25-hydroxy-vitamin D or PTH, except for ln-transformed 25OH-D and PFOS (β = 0.04; CI 95% 0.00-0.08). Stratified analyses confirmed the positive association between all considered PFAS and calcium in subjects not taking a VitD supplementation. Results show that high exposure levels to PFAS may interfere with calcium metabolism, independently of lifestyle and dietary factors. Further elucidation on the mechanisms underlying calcium homeostasis disruption, including multiple binding-equilibrium with serum albumin, remains to be addressed.

Assessing the utility of healthcare claims data to determine potential health impacts of PFAS exposure with public drinking water

Healthcare claims data can support the timely surveillance of health outcomes from exposures to emerging and established environmental contaminants such as per- and polyfluoroalkyl substances (PFAS). PFAS are widely used in a variety of consumer products and industrial applications. They are detected in almost all Americans. PFAS exposure has been associated with several health outcomes including high cholesterol and thyroid disease. In 2014, PFAS were detected in five drinking water wells in New Castle City, New Castle County, Delaware. Perfluorooctane sulfonate and perfluorooctanoic acid were measured above the then Environmental Protection Agency's lifetime health advisory of 70 parts per trillion. This study uses healthcare claims data to show that healthcare plan members living in the ZIP code served by the five wells were at higher risk for type 2 diabetes, hypertension, hypertensive diseases, coronary artery disease, and hyperthyroidism based on new claims compared with healthcare plan members living elsewhere in the county. Healthcare claims data provided timely information on health outcomes not captured by traditional public health surveillance systems and at finer geographic levels.

Perfluorooctanoic acid and perfluorooctane sulfonate inhibit in vitro osteogenesis: possible role of connexin 43-mediated gap-junctional intercellular communication

In the current study, we investigated the effects of two legacy per- and polyfluoroalkyl substances (PFASs) namely perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) on osteogenesis. The alterations of connexin 43 (Cx43)-mediated gap junctions (GJs) were further explored as a potential mechanism. The two cell models (C3H10T1/2 and MC3T3-E1 cells) differentiated into osteoblasts (OBs) were utilized, and treated with PFOA and PFOS at the doses of 0.25, 2.5, 25, and 75 μM. Real-time PCR and Western blot were applied to assess the mRNA and protein expression of osteogenic-specific markers and Cx43. ALP staining and ARS staining were used to evaluate the osteogenesis process. The scrape-loading dye transfer assay was performed to assess the GJ-mediated intercellular coupling. To investigate the role of gap-junctional intercellular communication (GJIC) in the PFAS-induced osteogenic inhibition, the Cx43-specific GJIC enhancer, rotigaptide (ZP123), was added into the differentiation medium of C3H10T1/2 cells. After the exposure of PFOA and PFOS, the osteogenic molecules were down-regulated and the calcium deposition was reduced in the two cell models, indicating the inhibitory effects of the legacy PFASs. The Cx43 expression and GJIC activity were significantly suppressed, and the usage of ZP123 rescued the adverse impact on osteogenesis, suggesting the remarkable role of GJIC herein.

Per- and polyfluoroalkyl substances in environment and potential health impacts: Sources, remediation treatment and management, policy guidelines, destructive technologies, and techno-economic analysis

Per- and polyfluoroalkyl Substances (PFAS), also known as forever chemicals and ubiquitous persistence, pose significant public health challenges due to their potential toxicity, particularly in drinking water and soil contamination. However, PFAS occurrence and their concentrations in different environmental matrices vary globally, but factors influencing trends, transport, fate, toxicity, and interactions with co-contaminants remain largely unexplored. Therefore, this review critically examines the state-of-the-art worldwide PFAS sources, distribution, and pathways, and evaluates how PFASs are processed in wastewater treatment, generally, which causes severe problems with the quality and safety of drinking water. Importantly, the review also underscores health issues due to PFAS consumption and recent research trends on developing effective treatment strategies to manage PFAS contamination. Potential effects of PFAS were linked to urban land use and the proportion of wastewater effluent in streamflow. Besides, major emphasis was provided on challenges for conventional treatment, destructive technologies, environmental accumulation, precursor transformation, and cost-investment related to PFAS removal technologies. To combat PFAS contamination, this review proposes a framework that promotes the comprehensive identification of prevalent compounds, with a focus on their eradication through knowledge-based and targeted analysis. Additionally, it explores the ongoing debate surrounding PFAS laws and legal frameworks, offering ideas for enhancing contamination management. Lastly, this review provides a strategic plan for improving response and preparedness, serving as a foundation for addressing future environmental challenges and informing health risk assessments.

Computational insights into the inhibitory effects of PFAS 14 on colorectal cancer targeting GSTA1 through competitive binding

This study employed computational biology approaches to investigate the interactions between per- and polyfluoroalkyl substances (PFAS) and key colorectal cancer (CRC) proteins. The results indicate that PFAS may influence CRC progression by modulating multiple proteins, particularly glutathione S-transferase A1 (GSTA1). Computational analysis revealed that PFAS 14 exhibits high binding affinity for GSTA1, occupying its glutathione-binding site. Further simulations confirmed the stable binding of PFAS 14 across different environments, forming persistent hydrogen bonds and water bridges, suggesting a potential inhibitory effect on GSTA1.GSTA1, a key member of the glutathione S-transferase family, plays a critical role in detoxification by catalyzing the conjugation of glutathione to electrophilic compounds. Dysregulation of GSTA1 has been implicated in cancer progression and chemoresistance. In CRC, altered GSTA1 expression may affect tumor metabolism and drug response, making it a potential therapeutic target.This study identifies GSTA1 as a key target of PFAS interactions, suggesting that environmental PFAS exposure may influence CRC by interfering with detoxification mechanisms. The competitive inhibition of GSTA1 by PFAS 14 may impact cancer cell survival and progression. Future research should integrate experimental validation to assess its phenotypic effects and evaluate PFAS 14 as a potential GSTA1 inhibitor.

Per- and polyfluoroalkyl substances as persistent pollutants with metabolic and endocrine-disrupting impacts

The widespread use of per- and polyfluoroalkyl substances (PFASs), and their resistance to degradation, renders human exposure to them inevitable. PFAS exposure disturbs endocrine function, potentially affecting cognitive development in newborns through thyroid dysfunction during pregnancy. Recent studies reveal varying male and female reproductive toxicity across PFAS classes, with alternative analogs affecting sperm parameters and legacy PFASs correlating with conditions like endometriosis. Metabolically, PFASs exposure is linked to metabolic disorders, including obesity, type 2 diabetes mellitus (T2DM), dyslipidemia, and liver toxicity, particularly in early childhood. This review focuses on the endocrine-disrupting impact of PFASs, particularly on fertility, thyroid, and metabolic functions. We highlight the complexity of the PFAS issue, given the large number of molecules and their extremely diverse mixed effects.

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

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

Poly- and per-fluoroalkyl substances toxicity on skeletal and cognitive well-being: a comprehensive review

Poly- and per-fluoroalkyl substances (PFAS) are a large group of synthetic compounds having a wide array of use in consumer products and industries, such as fire suppressant foam, nonstick cookware, paper, water-proof textiles, surfactants, aeronautics, and cosmetics. This widespread distribution of PFAS, their capacity to accumulate in living organisms, and their harmful effects represent a rising concern for public health. A multitude of studies have presented information on exposure to PFAS and a broad spectrum of adverse health outcomes through animal models and observational studies. Here, we have reviewed various studies that are related to PFAS toxicity on bone and brain and its underlying mechanisms. PFAS have well-established toxicological effects on bone, such as reduced osteoblastic and increased osteoclastic activity, increased activation of peroxisome proliferator activated receptor-γ (PPAR-γ), and increased expression of WNT11. With respect to brain, PFAS have been linked with autism, somnolence, sleep disturbances, glioma, Alzheimer's, decreased cognition, increased expression of Glycogen Synthase β (GSK3β). Further research is required in several areas, such as age-specific toxicological effects of PFAS, impact of various other PFAS compounds beyond perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), and involvement of peroxisome proliferator-activated receptors in PFAS-induced toxicity. Regarding brain toxicity, extensive research in adults is required as there is currently a relative scarcity of studies in this age group when compared to the available research conducted on children and older individuals.

Maternal concentrations of perfluoroalkyl sulfonates and alterations in white matter microstructure in the developing brains of young children

BACKGROUND

Maternal exposure to per- and polyfluoroalkyl substances (PFAS) has been linked to child neurodevelopmental difficulties. Neuroimaging research has linked these neurodevelopmental difficulties to white matter microstructure alterations, but the effects of PFAS on children's white matter microstructure remains unclear. We investigated associations between maternal blood concentrations of six common perfluoroalkyl sulfonates and white matter alterations in young children using longitudinal neuroimaging data.

METHODS

This study included 84 maternal-child pairs from a Canadian pregnancy cohort. Maternal second trimester blood concentrations of perfluorohexanesulfonate (PFHxS) and five perfluorooctane sulfonate (PFOS) isomers were quantified. Children underwent magnetic resonance imaging scans between ages two and six (279 scans total). Adjusted linear mixed models investigated associations between each exposure and white matter fractional anisotropy (FA) and mean diffusivity (MD).

RESULTS

Higher maternal concentrations of perfluoroalkyl sulfonates were associated with higher MD and lower FA in the body and splenium of the corpus callosum of young children. Multiple sex-specific associations were found. In males, PFHxS was negatively associated with FA in the superior longitudinal fasciculus, while PFOS isomers were positively associated with MD in the inferior longitudinal fasciculus (ILF). In females, PFOS isomers were positively associated with FA in the pyramidal fibers and MD in the fornix, but negatively associated with MD in the ILF.

CONCLUSION

Maternal exposure to perfluoroalkyl sulfonates may alter sex-specific white matter development in young children, potentially contributing to neurodevelopmental difficulties. Larger studies are needed to replicate these findings and examine the neurotoxicity of these chemicals.

Mass Spectrometry-Based Spatial Multiomics Revealed Bioaccumulation Preference and Region-Specific Responses of PFOS in Mice Cardiac Tissue

The distribution and bioaccumulation of environmental pollutants are essential to understanding their toxicological mechanism. However, achieving spatial resolution at the subtissue level is still challenging. Perfluorooctanesulfonate (PFOS) is a persistent environmental pollutant with widespread occurrence. The bioaccumulation behavior of PFOS is complicated by its dual affinity for phospholipids and protein albumin. It is intriguing to visualize the distribution preference of PFOS and investigate the differential microenvironment responses at a subtissue level. Herein, we developed a mass-spectrometry (MS)-based spatial multiomics workflow, integrating matrix-assisted laser desorption/ionization MS imaging, laser microdissection, and liquid chromatography MS analysis. This integrated workflow elucidates the spatial distribution of PFOS in mouse cardiac tissue, highlighting its preferential accumulation in the pericardium over the myocardium. This distribution pattern results in greater toxicity to the pericardium, significantly altering cardiolipin levels and disrupting energy metabolism and lipid transport pathways. Our integrated approach provides novel insights into the bioaccumulation behavior of PFOS and demonstrates significant potential for revealing complex molecular mechanisms underlying the health impacts of environmental pollutants.

Per- and polyfluoroalkyl substances in untreated and treated sludge/biosolids from 27 water resource recovery facilities across the United States and Canada

Per- and polyfluoroalkyl substances (PFAS) are being studied in all environmental matrices because of their ubiquitous presence and adverse human health impacts. This study conducted a surveillance of 27 water resource recovery facilities throughout the United States and Canada to screen the range of PFAS concentrations in pre-stabilized sludge and post-stabilized product. Among the 27 water resource recovery facilities, 82% use anaerobic digestion and the rest use chemical stabilization and/or incineration for sludge stabilization. Forty PFAS compounds were evaluated by US Environmental Protection Agency Method SW846/537.1, and four and nine compounds were reported in the pre-stabilized sludge and post-stabilized product, respectively. Concentrations of reported compounds in pre-stabilized sludge and post-stabilized product varied from 5 to 33 ng/g dry basis and 2 to 220 ng/g dry basis, respectively. 3-Perfluoropentylpropanoic acid (5:3 FTCA) and perfluorooctanesulfonic acid (PFOS) were the most frequently observed compounds, and PFAS concentrations in the post-stabilized products were generally higher than the corresponding pre-stabilized sludge. PRACTITIONER POINTS: Among the 40 target PFAS, four were above reporting limit in the pre-stabilized sludge and nine in the post-stabilized product. Incineration ash (post-stabilized product) samples did not have any reportable PFAS. 5:3 FTCA and PFOS were the two frequently observed compounds; concentrations were higher in the post-stabilized product compared to the pre-stabilized sludge. PFPeA and PFHxA were the only two short chain perfluoroalkyl carboxylic acids reported. PFOA was reported in only one of the 54 samples evaluated.

Pillar[5]arene-based Polymer Network for Efficiently Removing Perfluorooctanoic Acid through Synergistic Binding Interactions

Perfluorooctanoic acid (PFOA) is currently one of the most important chemicals posing environmental risks, and there is an urgent need to find methods to efficiently remove PFOA from environmental media. Here, two decaamino-pillar[5]arene-based fluorine-rich polymer networks, called FA2P-P and FA6P-P, were constructed using a convenient method. FA6P-P had an excellent ability to take up PFOA, and had a capacity of 1423 (mg PFOA) (g FA6P-P)-1, which is the second highest adsorption capacity reported for any PFOA sorbent. FA6P-P removed >99 % of the PFOA from a solution and decreased the PFOA concentration from 1000 μg L-1 in 5 min at an exceedingly low adsorbent loading of 0.7 mg L-1, giving a final PFOA concentration <4 ng L-1, which is lower than the most recent enforceable maximum concentration set by the United States Environmental Protection Agency. A high rate constant (kobs) of 55.8 g mg-1 h-1 was observed. Pillar[5]arene gives the material hydrophobic properties and also amino sites and hydrophobic chains, which are synergistic PFOA binding sites. The polymer was very stable and readily regenerated. The results indicated that pillar[5]arene-based porous organic polymer sorbents are excellent candidates for capturing PFOA.

Exposure to per- and poly-fluoroalkyl substances and lung, head and neck, and thyroid cancer: A systematic review and meta-analysis

Recent evidence suggests that exposure to per- and polyfluoroalkyl substances (PFAS) may increase the risk of different cancer types, such as kidney and testicular cancers. Instead, evidence for lung, head and neck, and thyroid cancer is sparse. Hence, we aimed to summarize available literature on the topic. We searched Pubmed and Scopus in January 2024 to retrieve relevant studies and estimated pooled relative risks (RRs) and 95% confidence intervals (CIs) for lung, head and neck, and thyroid cancers according to PFAS exposure using restricted maximum likelihood method. Pooled RRs for occupational or environmental PFAS exposure were 1.20 (95% CI: 1.12-1.28; I2 = 0.0%, phet = 0.9; n. studies = 9), 1.15 (95% CI: 0.96-1.37; I2 = 0.0%, phet = 0.7; n. studies = 3), and 1.54 (95% CI: 0.86-2.78; I2 = 69.0%, phet = 0.02; n. studies = 4) for lung, head and neck, and thyroid cancer, respectively. We did not find compelling evidence of publication bias for lung cancer (p = 0.3). Studies on statistically modelled serum PFAS levels did not support associations with these cancers. We found no positive associations between measured serum levels of 6 different types of PFAS and thyroid cancer. However, the pooled RR of two case-control studies nested within cohorts on the association between natural log-unit increase of perfluorooctanesulfonic acid (PFOS) and thyroid cancer was 1.51 (95% CI: 1.11-2.05; I2 = 21.1%, phet = 0.3). PFAS exposure may be associated with lung and thyroid cancer. Due to the limited number of studies and their limitations, further prospective studies with appropriate account of co-exposure with other carcinogens and detailed exposure assessment are needed to establish causality of observed associations.

Bone cell differentiation and mineralization in wild-type and osteogenesis imperfecta zebrafish are compromised by per- and poly-fluoroalkyl substances (PFAS)

Perfluorinated compounds (PFAS) are well recognized toxic pollutants for humans, but if their effect is equally harmful for healthy and fragile people is unknown. Addressing this question represents a need for ensuring global health and wellbeing to all individuals in a world facing the progressive increase of aging and aging related diseases. This study aimed to evaluate the impact of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorohexanoic acid (PFHxA) exposure on development and skeletal phenotype using the osteogenesis imperfecta (OI) zebrafish model Chihuahua (Chi/+), carrying a dominant glycine substitution in the α1 chain of collagen I and their wild-type (WT) littermates. To this purpose Chi/+ and WT zebrafish expressing the green fluorescent protein under the early osteoblast marker osterix were exposed from 1 to 6 days post fertilization to 0.36, 1.5 and 3.0 mg/L PFOS, 0.005 and 0.5 mg/L PFOA and 0.01, 0.48 and 16.0 mg/L PFHxA, and their development and skeletal phenotype investigated. Morphometric measurements, confocal microscopy evaluation of operculum area delimited by the fluorescent preosteoblasts and mineral deposition analysis following alizarin red staining were employed. PFOS and the highest concentration of PFHxA significantly impaired standard length in both genotypes. Osteoblast differentiation was significantly compromised by PFOS and by PFOA only in Chi/+. Limited to WT exposed to PFOA a reduced mineralization was also observed. No effect was detected after PFHxA exposure. Apoptosis was only activated by PFOA, specifically in Chi/+ mutant operculum osteoblasts. Interestingly, an altered lipid distribution in both WT and mutant fish was revealed after exposure to both pollutants. In conclusion, our data demonstrate that PFAS impair operculum development mainly compromising cell differentiation in mutant fish whereas alter lipid hepatic distribution in both genotypes with a more severe effect on Chi/+ preosteoblast survival. These results represent a first warning sign of the negative impact of PFAS exposure in presence of genetically determined skeletal fragility.

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

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

Perfluorooctane sulfonate (PFOS) induced bone loss by inhibiting FoxO1-mediated defense against oxidative stress in osteoblast

Exposure to perfluorooctane sulfonate (PFOS) has been associated with lower bone density and the occurrence of osteoporosis in human studies, but the effects and mechanisms of PFOS induces bone loss is not well understood. Our research is aimed at examining the effects of PFOS on osteoblastic activity and investigating the toxicological mechanisms of PFOS-induced bone loss. Cell proliferation, ALP activity, bone nodule formation, ROS levels, and cell apoptosis were assessed after treating osteoblasts with different concentrations of PFOS. Through transcriptome analysis, the differentially expressed genes (DEGs) were screened and the biofunctions were elucidated by Kyoto Encyclopedia of Genes and Genomes (KEGG) and The Gene Set Enrichment Analysis (GSEA). Vation of important genes and protein expression was accomplished using RT-PCR and Western blot methods, respectively. The results show that PFOS can reduce bone formation markers and improve oxidative stress and cell apoptosis. The DEGs in PFOS-treated groups were involved in multiple pathways, including FoxO, HIF-1, Rap1, Hippo, and sphingolipid signaling. FoxO1 was validated as the key gene which regulates osteogenic differentiation and redox status. Our findings suggest that PFOS reduces bone formation through FoxO1-mediated oxidative stress and apoptosis, as well as inhibition of the OPG/RANKL and FoxO1/β-catenin pathways. It will be beneficial for early intervention or treatment of PFOS-induced bone loss, highlighting the importance of regulatory measures to limit human exposure to PFOS.

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

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

Broad PFAS binding with fatty acid binding protein 4 is enabled by variable binding modes

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous pollutants that bioaccumulate in wildlife and humans, yet the molecular basis of their protein interactions remains poorly understood. Here, we show that human adipocyte fatty acid-binding protein (FABP4) can bind a diverse array of PFAS, including next-generation replacements for legacy chemicals and longer-chain perfluorocarboxylic acids. Shorter-chain PFAS, although weaker binders, still displayed measurable affinities-surpassing those of their nonfluorinated analogs. We determined crystal structures of FABP4 bound to perfluorooctanoic acid (PFOA), perfluorodecanoic acid (PFDA), and perfluorohexadecanoic acid (PFHxDA), revealing three distinct binding modes. Notably, PFOA binds in two separate sites, and two distinct conformations define single-ligand binding of PFDA and PFHxDA. These arrangements enhance hydrophobic interactions within the binding cavity and likely explain the low micromolar dissociation constants observed in fluorescence competition assays. Our findings underscore the critical roles of chain length, headgroup functionality, and protein conformation in PFAS-FABP4 interactions. Given the emerging implications of the role of FABP4 in endocrine function, even subtle PFAS-induced perturbations could affect metabolic regulation and disease risk. Overall, this work highlights the value of direct structural and biochemical insights into PFAS-FABP4 interactions and paves the way for future research on PFAS transport and toxicological outcomes.

Perfluorooctanoic acid and its alternatives disrupt the osteogenesis and osteoclastogenesis balance: Evidence from the effects on cell differentiation process

In the present study, we investigated the effects of a representative of the per- and polyfluoroalkyl substance (PFAS) chemical group, namely perfluorooctanoic acid (PFOA), and its alternatives (perfluorobutanoic acid [PFBA] and the hexafluoropropylene oxide dimer acid [GenX]) on bone homeostasis, a process that mainly depends on osteoblast (OB) and osteoclast (OC) activities at the cellular level. C3H10T1/2 cells and bone marrow macrophages (BMMs) were respectively induced into OBs and OCs, and treated with PFOA, PFBA, and GenX at doses of 0.25, 2.5, and 25 μM. Real-time PCR, ALP activity analysis, ARS staining, and TRAP staining were performed to assess cell differentiation. To explore the indirect effects on OC differentiation, conditioned media were collected from 7-day PFAS-treated C3H10T1/2 cells during differentiation. RANKL/OPG expression and secretion levels in C3H10T1/2 cells were determined, and BMMs induced into OCs were incubated in conditioned media for two days. PFOA suppressed osteogenesis characterized by the decreased mRNA expression of OB-specific molecules, ALP activity, and calcium deposition, and promoted osteoclastogenesis as evidenced by upregulated osteoclastic genes and increased number of TRAP-positive cells. Although the PFOA alternatives did not affect early osteogenesis, calcium deposits were significantly reduced and osteoclastogenesis was facilitated. The results suggested that PFOA and its alternatives could directly disturb the balance between osteogenesis and osteoclastogenesis. In addition, PFOA and its alternatives enhanced the RANKL/OPG ratio during early OB differentiation, and more BMMs stimulated with the conditioned medium differentiated into OCs, indicating the indirect stimulation on OC differentiation by PFOA and its alternatives. These findings highlight the potential skeletal hazards of PFASs, particularly emerging alternatives that might be ignored, offering a toxicological basis for further exploration.

Maternal transfer and sex-differences in brain bioaccumulation for Northern bobwhite quail (Colinus virginianus) exposed to per- and poly-fluoroalkyl substances

Per- and poly-fluoroalkyl substances (PFAS) are highly persistent chemicals commonly found in surface protectants, and class B aqueous film forming foams (AFFF), and many other consumer and industrial products. As a result of their widespread application and use, PFAS are now found in environmental media across the globe. Research has revealed that exposure to environmentally relevant concentrations of PFAS can reduce reproductive success and have immunological effects in laboratory animals, including birds. Further, PFAS can be passed down from parents to offspring, posing a threat to sensitive life stages. PFAS may enter the brain by disrupting tight junctions or binding to transporters, but our overall understanding of the interactions and accumulation of PFAS in the avian brain is limited due to the lack of data. We obtained archived samples of male-female pairs of Northern bobwhite quail (NBWQ) from chronic toxicity studies where adults were exposed to either individual PFAS or binary mixtures through drinking water for at least 60 days. PFAS were detected in the brains of exposed adult quail, while brains from control birds had only occasional detections of PFAS; mostly perfluorooctane sulfonic acid (PFOS), likely because our source of birds was pen-raised animals and many PFAS are ubiquitous. Despite similar average daily intake (ADI) for both males and females, we observed higher concentrations of most PFAS in the brains of male birds compared to female birds, with the exception of perfluoroheptanoic acid (PFHpA). For the binary mixture exposures, PFOS appeared to reduce brain concentrations of perfluorohexane sulfonic acid (PFHxS) in both males and females to levels that could not be explained by ADI differences alone. Collectively, study results demonstrated that brain accumulation of short-chain PFAS in birds was not significantly affected by sex, however, long-chain PFAS exposure resulted in avian brain accumulation with generally higher PFAS concentrations in males compared to females. The findings of this study offer insights into the accumulation of PFAS in the avian brain and suggest that there may be sex differences in potential risks associated with exposure to these pervasive chemicals.

Prenatal exposure to perfluoroalkyl and polyfluoroalkyl substances and childhood bone mineral density: A prospective birth cohort study

BACKGROUND AND AIM

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) have demonstrated potential toxicity in skeletal development. However, the relationship between prenatal PFAS exposure and offspring bone health remains unclear in epidemiological studies. Therefore, we aim to investigate whether prenatal exposure to PFAS is associated with bone mineral density (BMD) in offspring.

METHOD

This study population included 182 mother-child pairs in the Shanghai Obesity and Allergy Cohort, enrolled during 2012-2013. 10 PFAS were measured by liquid chromatography-mass spectrometry (LC-MS) in cord plasma. The child's spinal BMD was measured using a dual-energy X-ray absorptiometry (DXA) scanner at the age of 8. Multivariable linear regression models were used to estimate the associations between individual PFAS concentrations (as a continuous variable or categorized into quartiles) and child BMD. Bayesian kernel machine regression (BKMR) was employed to explore the joint effects of PFAS mixtures on BMD.

RESULTS

Among the 10 PFAS, 8 of them had a detection rate >90% and were included in the subsequent analysis. We observed no significant associations between individual PFAS (as a continuous variable) and spinal BMD in 8-year-old children using the multivariable linear regression model. When treated as quartile categories, the second and fourth quartiles of perfluorobutane sulfonate (PFBS) was associated with higher BMD in the first lumbar vertebra, compared with the lowest quartile. BKMR analysis revealed no association between the PFAS mixture and child BMD.

CONCLUSION

We observed no associations of prenatal PFAS exposure with child BMD at 8 years of age. Given the inconsistent epidemiological evidence, further research is needed to confirm these findings from other studies or elucidate the potentially toxic effects of PFAS on bone.

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

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

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

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

Increased perfluorooctanoic acid accumulation facilitates the migration and invasion of lung cancer cells via remodeling cell mechanics

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are widely used in industrial and household products, raising serious concerns due to their environmental persistence and mobility. Epidemiological studies have reported potential carcinogenic risks of PFAS based on their widespread occurrence and population exposure. In this study, we observed that perfluorooctanoic acid (PFOA), a common PFAS, functions as a mechanical regulator in lung cancer cells. PFOA exposure reduces cell stiffness, thereby decreasing cell adhesion and enhancing immune evasion, ultimately exacerbating tumor metastasis. In various lung cancer models, more aggressive tumor metastases have been observed in the PFOA exposure group. Additionally, serum PFOA levels in patients with advanced lung adenocarcinoma were significantly higher than those in patients with early-stage disease. Mechanistically, the interaction between PFOA and transmembrane integrins in cancer cells triggers changes in cellular mechanical properties, leading to the reorganization of the cytoskeleton, and activation of the intracellular FAK-PI3K-Akt signaling pathway. Our findings demonstrate that in individuals with lung adenocarcinoma, PFOA can increase the risk of cancer metastasis even at daily exposure levels.

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

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

Pyrolysis of Two Perfluoroalkanesulfonates (PFSAs) and PFSA-Laden Granular Activated Carbon (GAC): Decomposition Mechanisms and the Role of GAC

Thermal treatment of perfluoroalkyl and polyfluoroalkyl substances (PFASs) presents a promising opportunity to halt the PFAS cycle. However, how co-occurring materials such as granular activated carbon (GAC) influence thermal decomposition products of PFASs, and underlying mechanisms remain unclear. We studied the pyrolysis of two potassium salts of perfluoroalkanesulfonates (PFSAs, CnF2n+1SO3K), perfluorobutanesulfonate (PFBS-K), and perfluorooctanesulfonate (PFOS-K), with or without GAC. PFBS-K is more stable than PFOS-K for pure standards, but when it is adsorbed onto GAC, its thermal stabilities and decomposition behaviors are similar. Temperatures and heating rates can significantly influence the decomposition mechanisms and products for pure standards, while these effects are less pronounced when PFSAs are adsorbed onto GAC. We further studied the underlying decomposition mechanisms. Pure standards of CnF2n+1SO3K can decompose directly in their condense phase by reactions: F(CF2)nSO3K → F(CF2)n-2CF═CF2 + KFSO3 or F(CF2)nSO3K → F(CF2)n- + K+ + SO3. GAC appears to facilitate breakage of the C-S bond to release SO2 at temperatures as low as 280 °C. GAC promotes fluorine mineralization through functional reactive sites. SiO2 is particularly important for the surface-mediated mineralization of PFASs into SiF4. These findings offer valuable insights into optimizing thermal treatment strategies for PFAS-contaminated waste.

Neurotoxicity of per- and polyfluoroalkyl substances: Evidence and future directions

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals widely used in various products, including food packaging, textiles, and firefighting foam, owing to their unique properties such as amphiphilicity and strong CF bonds. Despite their widespread use, concerns have arisen due to their resistance to degradation and propensity for bioaccumulation in both environmental and human systems. Emerging evidence suggests a potential link between PFAS exposure and neurotoxic effects, spanning cognitive deficits, neurodevelopmental disorders, and neurodegenerative diseases. This review comprehensively synthesizes current knowledge on PFAS neurotoxicity, drawing insights from epidemiological studies, animal experiments, and mechanistic investigations. PFAS, known for their lipophilic nature, tend to accumulate in lipid-rich tissues, including the brain, breaching biological barriers such as the blood-brain barrier (BBB). The accumulation of PFAS within the central nervous system (CNS) has been implicated in a spectrum of neurological maladies. Neurotoxicity induced by PFAS manifests through a multitude of direct and indirect mechanisms. A growing body of research associated PFAS exposure with BBB disruption, calcium dysregulation, neurotransmitter alterations, neuroinflammation, oxidative stress, and mitochondrial dysfunction, all contributing to neuronal impairment. Despite notable strides in research, significant lacunae persist, necessitating further exploration to elucidate the full spectrum of PFAS-mediated neurotoxicity. Prospective research endeavors should prioritize developing biomarkers, delineating sensitive exposure windows, and exploring mitigation strategies aimed at safeguarding neurological integrity within populations vulnerable to PFAS exposure.

When subcellular chemical imaging enlightens our understanding on intestinal absorption, intracellular fate and toxicity of PFOA in vitro

Perfluorooctanoic acid (PFOA) is a persistent organic pollutant that accumulates in the human body, leading to major health issues. Upon oral uptake, the gastrointestinal tract is the first biological barrier against PFOA. However, the localization of PFOA and its impact on the intestinal wall are largely unknown. Here we achieve a breakthrough in the knowledge of intestinal absorption, intracellular fate and toxicity of PFOA using in vitro assays combined with novel analytical imaging techniques. For the first time, we localized PFOA in the cytosol of Caco-2 cells after acute exposure using high spatial resolution mass spectrometry imaging, and we estimated the PFOA cytosolic concentration. Knowing that PFOA enters and accumulates in the intestinal cells, we also performed common toxicity assays assessing cell metabolic activity, membrane integrity, oxidative stress response, and cell respiration. This study integrating powerful analytical techniques with widely used toxicology assays provides insightful information to better understand potential negative impacts of PFOA and opens new opportunities in toxicology and life science in general.

Binary and quaternary mixtures of perfluoroalkyl substances (PFAS) differentially affect the immune response to influenza A virus infection

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic organofluorine compounds that persist indefinitely in the environment and bioaccumulate throughout all trophic levels. Biomonitoring efforts have detected multiple PFAS in the serum of most people. Immune suppression has been among the most consistent effects of exposure to PFAS. PFAS often co-occur as mixtures in the environment, however, few studies have examined immunosuppression of PFAS mixtures or determined whether PFAS exposure affects immune function in the context of infection. In this study, mixtures containing two or four different PFAS and a mouse model of infection with influenza A virus (IAV) were used to assess immunotoxicity of PFAS mixtures. PFAS were administered via the drinking water as either a binary mixture of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) or quaternary mixture of PFOS, PFOA, perfluorohexane sulfonate (PFHxS), and perfluorononanoic acid (PFNA). The results indicated that the binary mixture affected the T-cell response, while the quaternary mixture affected the B-cell response to infection. These findings indicate that the immunomodulatory effects of PFAS mixtures are not simply additive, and that the sensitivity of immune responses to PFAS varies by cell type and mixture. The study also demonstrates the importance of studying adverse health effects of PFAS mixtures.

Assessing strategies to measure hidden per- and polyfluoroalkyl substances (PFAS) in groundwater and to evaluate adsorption remediation efficiencies

The widespread presence of per- and polyfluoroalkyl substances (PFAS) in the environment, driven by extensive industrial use, has raised global concerns due to their persistence and adverse health effects. Despite the increased regulatory focus on a sub-set of well-known PFAS, over 12,000 compounds exist, many poorly characterized. Our study assessed hidden PFAS concentrations, undetectable by standard LC-MS/MS analysis, in contaminated groundwater. We analyzed total oxidizable precursors (TOP) via TOP assay followed by LC-MS/MS, and total organic fluorine (TOF) via combustion ion chromatography (CIC). Results were compared with those from LC-MS/MS analysis of 25 individual PFAS (∑PFAS25), representing the non-hidden PFAS fraction. We also evaluated the removal of hidden PFAS employing conventional and novel adsorbents. Groundwater samples from drinking water sources and contaminated military sites in the USA showed varying PFAS contamination levels as indicated by TOF values ranging from non-detect (<0.7 μg L-1) to 40.2 μg L-1. ∑PFAS25 was a major fraction of the TOF (41.7 - 92.8%) in some samples, whereas in others it only accounted for 5.1 - 20.4% of the TOF. The remaining percentages consisted of hidden PFAS not detected by conventional LC-MS/MS, but detectable as TOF by CIC. Organic fluorine content of oxidizable precursors accounted for 0.0-39.0% of TOF content, depending on the sample. Selected samples underwent adsorption with activated carbon (AC), anion exchange resin (IX), polyaniline (PANI), and poly-o-toluidine (POT). All adsorbents removed the hidden PFAS less effectively than the PFAS quantified by direct LC-MS/MS techniques. This is likely because PFAS adsorbents investigated to date primarily target anionic per- and polyfluoroalkyl acids, not effectively removing cationic, neutral, or zwitterionic hidden PFAS. AC exhibited the best overall performance among the investigated adsorbents. The results demonstrate that measuring TOP and TOF concentrations is effective for evaluating the removal of hidden PFAS in groundwater remediation.