Epigenetic changes by per- and polyfluoroalkyl substances (PFAS)

Unveiling the effects of micro and nano plastics in embryonic development

The improper disposal and degradation of plastics causes the formation and spread of micro and nano-sized plastic particles in the ecosystem. The widespread presence of these micro and nanoplastics leads to their accumulation in the biotic and abiotic components of the environment, thereby affecting the cellular and metabolic functions of organisms. Despite being classified as xenobiotic agents, information about their sources and exposure related to reproductive health is limited. Micro and nano plastic exposure during early developmental stages can cause abnormal embryonic development. It can trigger neurotoxicity and inflammatory responses as well in the developing embryo. In embryonic development, a comprehensive study of their role in pluripotency, gastrulation, and multi-differentiation potential is scarce. Due to ethical concerns associated with the direct use of human embryos, pluripotent cells and its 3D in vitro models (with cell lines) are an alternative source for effective research. Thus, the 3D Embryoid body (EB) model provides a platform for conducting embryotoxicity and multi-differentiation potential research. Pluripotent stem cells such as embryonic and induced pluripotent stem cells derived embryoid bodies (EBs) serve as a robust 3D in vitro model that mimics characteristics similar to that of human embryos. Thus, the 3D EB model provides a platform for conducting embryotoxicity and multi-differentiation potential research. Accordingly, this review discusses the significance of 3D in vitro models in conducting effective embryotoxicity research. Further, we also evaluated the possible sources/routes of microplastic generation and analyzed their surface chemistry and cytotoxic effects reported till date.

Electrostatic and Chemical Interplay between Air-Water and Mineral-Water Interfaces during PFOS Transport in Unsaturated Porous Media

Perfluorooctanesulfonate (PFOS) migration from vadose zone sources to groundwater is determined by multiple interfacial retention processes and their dependency on hydrochemistry. This study investigates the impact of air-water and mineral-water interfacial retention on PFOS transport under different hydrochemical conditions to assess their adsorption magnitudes and feedback dynamics as a function of ionic strength. Flow-through experiments were conducted in unsaturated quartz and goethite-coated quartz sands equilibrated with different background electrolyte concentrations to distinguish between air-water and goethite-water interfacial adsorption contributions to PFOS retardation. Measurements of PFOS breakthrough curves at column outlets allowed tracking the differences in spatio-temporal evolution of the PFOS plumes between the two porous media. Process-based reactive transport simulations, incorporating a thermodynamic framework of mass-action reactions accounting for multiple interfacial retention processes, allowed the quantitative interpretation of physical and geochemical processes. Experimental and modeling results reveal that multiprocess retention causes nonideal PFOS transport, with plume retardation and spatio-temporal mass transfer between the different phases determined by the relative contribution of the individual retention processes and their electrostatic interplay driven by solution counterions. These findings illuminate the interplay between air-water and mineral-water sorption and emphasize the need for reactive transport simulators implementing interdependent interfacial retention processes, influenced by water chemistry conditions.

Physiological and Metabolic Responses of Wheat (Triticum aestivum L.) after One-Generation Exposure to Perfluorooctanesulfonic Acid (PFOS)

The pattern of plant responses, particularly on the seeds/grains metabolite profile, after generational exposure to contaminants is not well documented. Seeds from wheat cultivated in soil amended with PFOS at 0 and 25 mg/kg in the first generation were grown in clean soil to produce daughter plants and seeds in the second generation and assigned treatment combinations of 0-0 mg/kg PFOS and 25-0 mg/kg PFOS. Plant stress and responses including growth and biomass production, chlorophyll content, lipid peroxidation, and enzyme activity were measured over a short exposure period (21 days growth period). Biomass yields, elemental concentration, and grain metabolites were also measured after a long exposure period (92 days growth period). The daughter plants exhibited decreased chlorophyll content and lipid peroxidation in a short exposure period. The elemental concentrations were mostly not affected except for changes in microelements, except B, in the grains. In the metabolomics analysis, grains harvested from plants previously exposed to PFOS (i.e., 25-0 mg/kg PFOS) showed increased abundances of sucrose, linolenic acid, tryptophan, inositol-4-monophosphate, and ferulic acid, perhaps in response to adaptation to former stress. The current findings seem to suggest that one-generation exposure to PFOS does not cause detrimental effects on the next generation after the cessation of exposure. The results provide insights into the effects of generational exposure of plants to PFOS.

Multigeneration responses of Daphnia magna to short-chain per- and polyfluorinated substances (PFAS)

Short-chain per- and polyfluorinated substances (PFAS) are ubiquitous in the environment, but their chronic effects on aquatic organisms over multiple generations are often overlooked in environmental risk assessment. In this study, the ecotoxicity of perfluorobutane sulfonic acid (PFBS) and its precursor perfluorobutane sulfonamide (FBSA) to Daphnia magna was assessed under continuous exposure for six consecutive generations, with adult survival, reproduction, and population growth rate as endpoints. Observed effects were also related to internal PFAS concentrations in the daphnids. Compared to the first generation, both PFBS and FBSA showed intensified ecotoxicity over six generations, increasing by 1.8-3.0, and 3.6-6.4 times, respectively. Specifically, the EC50_r, water and LC50, water of PFBS decreased from 886 and > 1470 mg/L in the F0 generation to 470 and 483 mg/L, respectively in the F3 generation, while the EC50_r, water and EC50_repro, water of FBSA decreased from 12.4 and 7.08 mg/L in the F0 generation to 3.37 and 1.10 mg/L, respectively in the F5 generation. PFBS ecotoxicity increased as a result of elevated compound accumulation over generations, indicating a narcotic mode of action, whereas FBSA exerted specific reproductive toxicity, resulting in a more pronounced worsening of adverse effects over time. Compared to PFBS, FBSA was around 100 times more toxic in F0, escalating to over 435 times more toxic in F5, and also showed a higher bioaccumulation potential. These findings highlight that the conventional single-generation ecotoxicity tests underestimate PFAS ecotoxicity during multigeneration exposure, and that the environmental risks of PFAS cannot be reliably assessed by the current limited subset of studied compounds.

Exposure to per-and poly-fluoroalkyl substances and respiratory and skin effects in children and adolescents: A systematic review and meta-analysis

Despite being previously banned due to long-term health effects, Per- and polyfluoroalkyl substances (PFAS) remain widespread in the environment, accumulating in animals and humans. This systematic review and meta-analysis explores associations between exposure to PFAS and asthma onset, wheezing, atopic dermatitis, and eczema in children and adolescents while addressing exposure timing and sex-specific differences. After comprehensive search conducted in several databases, including risk of bias, study heterogeneity, and quality of evidence evaluation, the review included 28 observational studies, most with low risk of bias in all domains. PFAS exposure was not significantly associated with asthma onset (OR:1.03, CI:0.99;1.07), but revealed significantly lower association in the prenatal period (OR:0.97, CI:0.94;0.99), higher in the postnatal period (OR:1.20, CI:1.07;1.35), and no differences among sexes. PFAS exposure (mainly prenatal) was associated with 4 % significantly lower odds of wheezing (OR:0.96, CI:0.94;0.98), higher in girls (OR:0.94, CI:0.91;0.98) than in boys (OR:0.97, CI:0.94;1.00). No significant impact was noted on atopic dermatitis (OR:1.04, CI:0.94;1.16), while PFAS exposure was associated with 8 % significantly lower eczema odds (OR:0.92, CI:0.89;0.96). Evidence was insufficient to perform sensitivity analyses on atopic dermatitis and eczema. Additional research is needed on the impact of synergistic and co-exposure to other pollutants on children and adolescents' health.

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.

Persistent organic pollutants and plasma microRNAs: A community-based profiling analysis

BACKGROUND

Whether exposure to persistent organic pollutants (POPs) may incur microRNAs (miRNAs) dysregulation remains largely unclear.

OBJECTIVES

We aim to identify the miRNA signature and related pathways of low-level POPs exposure in a community-based population.

METHODS

We used general linear regression to model the association of POPs with plasma miRNAs, adjusting for age, gender, smoking, alcohol consumption, body mass index, triglyceride, and total cholesterol levels. We performed pathway enrichment analysis based on 11 experimentally validated and prediction-based databases, and performed tissue specificity analysis.

RESULTS

We identified 19 POPs significantly associated with 23 miRNAs at false discovery rate-adjusted P value < 0.2, most of which were related to organophosphorus and organochlorine pesticides. Pathway enrichment of the associated miRNAs highlighted chromosome segregation, RNA splicing, autophagy regulation, lipid metabolism, cell growth, development and differentiation, cell cycle regulation, neural network construction, and signal transduction. Notably, 13 POPs were positively associated with miR-6810-3p, a miRNA enriched in temporal lobe with high tissue specificity (Tissue Specificity Index = 0.78). Pathway analysis revealed that miR-6810-3p contributes to the positive regulation of autophagy and multiple cellular functions related to the nervous system such as transport along microtubules, maintenance of cell polarity, and synaptic transmission.

CONCLUSION

In conclusion, we identified POPs-related miRNA signatures in community-dwelling adults, and highlighted miR-6810-3p in association with multiple POPs, with a potential role in nervous system regulation.

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.

PFAS (per- and polyfluorinated alkyl substances) as EDCs (endocrine-disrupting chemicals) - Identification of compounds with high potential to bind to selected terpenoids NHRs (nuclear hormone receptors)

The objective of the subsequent study was to examine the probability of PFAS (per- and polyfluorinated alkyl substances) binding to various NHRs (nuclear hormone receptors) and to identify their structural features that contribute most to the binding score (BS). We evaluated the BS for PFAS in relation to 7 selected NHRs - 4 with additional antagonist forms (Retinoid X receptor alpha - RXRα, Liver X receptor alpha - LXRα, Liver X receptor beta - LXRβ, Estrogen receptor alpha - ERα, Estrogen receptor alpha antagonist - anti-ERα, Estrogen receptor beta - ERβ, Estrogen receptor beta antagonist - anti-ERβ, Glucocorticoid receptor - GR, Glucocorticoid receptor antagonist - anti-GR, Androgen receptor - AR, Androgen receptor antagonist - anti-AR). We based our study on the results of molecular docking, which we used to develop MLR-QSAR (Multiple Linear Regression - Quantitative Structure-Activity Relationship) models. The models we developed allowed us to predict the BS for an extensive set of PFAS compounds from the NORMAN database (more than 4000) - virtual screening. The probability of PFAS binding to selected receptors was determined by structural features such as particle size, branching, and fluorine content. These variables were also identified in the literature reports of experimental studies as the most important for this group of compounds. The research focused on receptors from the terpenoid group. The RXRα, LXRα and β, GR, and anti-GR receptors were shown to be the group less likely to be affected by PFAS. Sex hormones such as AR, anti-AR, ERα and ERβ with their antagonist forms are the most affected.

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.

Prenatal Perfluoroalkyl Substance Exposure in Association with Global Histone Post-Translational Methylation in 2-Year-Old Children

Perfluoroalkyl substances (PFASs) have elimination half-lives in years in humans and are persistent in the environment. PFASs can cross the placenta and impact fetal development. Exposure to PFASs may lead to adverse effects through epigenetic mechanisms. This study aimed to investigate whether prenatal exposure to perfluorooctyl sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluoroundecanoic acid (PFUA) was associated with global histone methylation level changes among the 130 2-year-old children followed-up in a birth cohort study in Taiwan. PFOS, PFOA, PFNA, and PFUA were measured by UHPLC/MS/MS in cord blood. Global histone methylation levels were measured from the blood leukocytes of 2-year-old children by Western blotting. Multivariable regression analyses were applied to adjust for potential confounding effects. Among the 2-year-old children, an IQR increase in the natural log-transformed PFUA exposure was associated with an increased H3K4me3 level by 2.76-fold (95%CI = (0.79, 4.73), p = 0.007). PFOA and PFNA exposures was associated with a decreased H3K27me3 level by 2.35-fold (95%CI = (-4.29, -0.41), p = 0.01) and 2.01-fold (95%CI = (-4.00, -0.03), p = 0.04), respectively. Our findings suggest that prenatal PFAS exposure affected histone post-translational modifications.

Per- and polyfluoroalkyl substances (PFAS) and cancer: Detection methodologies, epidemiological insights, potential carcinogenic mechanisms, and future perspectives

Per- and polyfluoroalkyl substances (PFAS), known as "forever chemicals," are synthetic chemicals which have been used since the 1940s. Given their remarkable thermostability and chemical stability, PFAS have been widely utilized in commercial products, including textiles, surfactants, food packages, nonstick coatings, and fire-fighting foams. Thus, PFAS are widely distributed worldwide and have been detected in human urine, blood, breast milk, tissues and other substances. Growing concerns over the risks of PFAS, including their toxicity and carcinogenicity, have attracted people's attention. Recent reviews have predominantly emphasized advancements in the detection, adsorption, and degradation of PFAS through their chemical structures and toxic properties; however, further examination of the literature is needed to determine the link between PFAS exposure and cancer risk. Here, we introduced different PFAS detection methods based on sensors and liquid chromatography-mass spectrometry (LC-MS). Then, we discussed epidemiological investigations on PFAS levels and cancer risks in recent years, as well as the mechanisms underlying the carcinogenesis. Finally, we proposed the "4C principles" for ongoing exploration and refinement in this field. This review highlights PFAS-cancer associations to fill knowledge gaps and provide evidence-based strategies for future research.

Examining the relationship between per-and polyfluoroalkyl substances and breast, colorectal, prostate, and ovarian cancers: a meta-analysis

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals used widely in industrial and commercial applications. Concerns exist about their potential link to cancer risk as possible endocrine-disrupting chemicals. We conducted a meta-analysis to evaluate the dose-response relationship between PFAS, perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluorohexanesulfonic acid (PFHxS) exposure and risk of breast, prostate, colorectal, and ovarian cancers. We systematically searched major databases through May 2022 and identified 13 observational studies for inclusion. Using random-effects models, we calculated summary odds ratios (ORs) and 95% confidence intervals (CIs) comparing the highest versus lowest PFAS exposure categories. Additionally, we analyzed the dose-response correlation between PFAS and cancer risk in a subset of studies. The study revealed no substantial correlation between exposure to PFASs and the incidence of breast cancer (BC) (ORPFOS = 1.15, 95% CI = 0.91-1.46, ORPFOA = 1.01, 95% CI = 0.68-1.50, ORPFNA = 0.88, 95% CI = 0.64-1.21, ORPFHxS = 1.22, 95% CI = 0.40-3.77, and ORPFDA = 1.29, 95% CI = 0.41-4.10), ovarian cancer (ORPFOA = 1.43, 95% CI = 0.84-2.42), prostate cancer (ORPFOA = 1.05, 95% CI = 0.88-1.26), and colorectal cancer (ORPFOA = 0.77, 95% CI = 0.53-1.12) in the highest versus lowest exposure analysis. However, dose-response analysis showed that for every 1 ng/ml increase in PFNA and 2 ng/ml increase in PFOA, the relative risk for BC decreased significantly (RR 0.67, 95% CI 0.45-0.99 and RR 0.94, 95% CI 0.89-0.98, respectively). Non-linear dose-response analysis found no significant changes in BC risk with increasing PFAS levels. In conclusion, while the highest versus lowest analysis does not support associations between PFAS exposure and the risk of these cancers, linear dose-response analysis suggests potential inverse relationships between PFNA/PFOA levels and BC risk. Further research is warranted on these potential protective effects.

Exposure to per- and polyfluoroalkyl substances is associated with impaired cardiovascular health: a cross-sectional study

Background

Per- and polyfluoroalkyl substance (PFAS) exposure and cardiovascular disease are controversial. We aimed to assess the association between serum PFAS exposure and cardiovascular health (CVH) in U.S. adults.

Methods

We analyzed serum PFAS concentration data of U.S. adults reported in the National Health and Nutrition Examination Survey (NHANES) study (2005-2018). We employed two weighted logistic regression models and a restricted cubic spline (RCS) to examine the association between each PFAS and impaired CVH (defined as moderate and low CVH). Quantile g-computation (Qgcomp) and weighted quantile sum (WQS) analysis were used to estimate the effects of mixed exposures to PFASs on impaired CVH.

Results

PFAS were associated with an increased risk of impaired CVH (ORPFNA: 1.40, 95% CI: 1.09, 1.80; ORPFOA: 1.44, 95% CI: 1.10, 1.88; ORPFOS: 1.62, 95% CI: 1.25, 2.11). PFOA and PFOS exhibited nonlinear relationships with impaired CVH. Significant interactions were observed for impaired CVH between race/ethnicity and PFHxS (p = 0.02), marital status and PFOA (p = 0.03), and both marital status and race/ethnicity with PFOS (p = 0.01 and p = 0.02, respectively). Analysis via WQS and Qgcomp revealed that the mixture of PFAS was positively associated with an increased risk of impaired CVH.

Conclusion

PFNA, PFOA, and PFOS exposure are associated with an increased risk of impaired CVH in U.S. adults. Race/ethnicity and marital status may influence CVH. Reducing PFAS exposure could alleviate the burden of disease associated with impaired CVH.

Identifying the plasma metabolome responsible for mediating immune cell action in severe COVID-19: a Mendelian randomization investigation

Introduction

The immune response regulates the severity of COVID-19 (sCOVID-19). This study examined the cause-and-effect relationship between immune cell traits (ICTs) and the risk of severe COVID-19. Additionally, we discovered the potential role of plasma metabolome in modulating this risk.

Methods

Employing data from a genome-wide association study (GWAS), we conducted a two-sample Mendelian randomization (MR) assessment of 731 genetic ICTs and sCOVID-19 (5,101 cases, 1,383,241 controls) incidence. The MR analysis was utilized to further quantitate the degree of plasma metabolome-mediated regulation of immune traits in sCOVID-19.

Results

The inverse variance weighted method recognized 2 plasma metabolites (PMs) responsible for casual associations between immune cells and sCOVID-19 risk. These included Tridecenedioate (C13:1-DC) which regulated the association between CD27 on IgD- CD38br (OR 0.804, 95% CI 0.699-0.925, p = 0.002) and sCOVID-19 risk (mediated proportion: 18.7%); arginine to citrulline ratio which controlled the relationship of CD39 on monocyte (OR 1.053, 95% CI 1.013-1.094, p = 0.009) with sCOVID-19 risk (mediated proportion: -7.11%). No strong evidence that genetically predicted sCOVID-19 influenced the aforementioned immune traits.

Conclusion

In this study, we have successfully identified a cause-and-effect relationship between certain ICTs, PMs, and the likelihood of contracting severe COVID-19. Our findings can potentially improve the accuracy of COVID-19 prognostic evaluation and provide valuable insights into the underlying mechanisms of the disease.

Multicomponent and Surface Charge Effects on PFOS Sorption and Transport in Goethite-Coated Porous Media under Variable Hydrochemical Conditions

Perfluorooctanesulfonate (PFOS), a toxic anionic perfluorinated surfactant, exhibits variable electrostatic adsorption mechanisms on charge-regulated minerals depending on solution hydrochemistry. This work explores the interplay of multicomponent interactions and surface charge effects on PFOS adsorption to goethite surfaces under flow-through conditions. We conducted a series of column experiments in saturated goethite-coated porous media subjected to dynamic hydrochemical conditions triggered by step changes in the electrolyte concentration of the injected solutions. Measurements of pH and PFOS breakthrough curves at the outlet allowed tracking the propagation of multicomponent reactive fronts. We performed process-based reactive transport simulations incorporating a mechanistic network of surface complexation reactions to quantitatively interpret the geochemical processes. The experimental and modeling outcomes reveal that the coupled spatio-temporal evolution of pH and electrolyte fronts, driven by the electrostatic properties of the mineral, exerts a key control on PFOS mobility by determining its adsorption and speciation reactions on goethite surfaces. These results illuminate the important influence of multicomponent transport processes and surface charge effects on PFOS mobility, emphasizing the need for mechanistic adsorption models in reactive transport simulations of ionizable PFAS compounds to determine their environmental fate and to perform accurate risk assessment.

Epigenetics and environmental health

Epigenetic modifications including DNA methylation, histone modifications, chromatin remodeling, and RNA modifications complicate gene regulation and heredity and profoundly impact various physiological and pathological processes. In recent years, accumulating evidence indicates that epigenetics is vulnerable to environmental changes and regulates the growth, development, and diseases of individuals by affecting chromatin activity and regulating gene expression. Environmental exposure or induced epigenetic changes can regulate the state of development and lead to developmental disorders, aging, cardiovascular disease, Alzheimer's disease, cancers, and so on. However, epigenetic modifications are reversible. The use of specific epigenetic inhibitors targeting epigenetic changes in response to environmental exposure is useful in disease therapy. Here, we provide an overview of the role of epigenetics in various diseases. Furthermore, we summarize the mechanism of epigenetic alterations induced by different environmental exposures, the influence of different environmental exposures, and the crosstalk between environmental variation epigenetics, and genes that are implicated in the body's health. However, the interaction of multiple factors and epigenetics in regulating the initiation and progression of various diseases complicates clinical treatments. We discuss some commonly used epigenetic drugs targeting epigenetic modifications and methods to prevent or relieve various diseases regulated by environmental exposure and epigenetics through diet.

Per-polyfluoroalkyl substances (PFAS) as thyroid disruptors: is there evidence for multi-transgenerational effects?

INTRODUCTION

The environmental spread of pollutants has led to a persistent exposure of living beings to multiple chemicals, by now become ubiquitous in the surrounding environment. Environmental exposure to these substances has been reported to cause multi- and/or transgenerational health effects. Per- and Polyfluorinated Substances (PFAS) raise great concern, given their known effects both as endocrine disruptors and potential carcinogens. The multi/trans-generational effects of different endocrine disruptors have been investigated by several studies, and harmful effects observed also for PFAS.

AREAS COVERED

This review examines the current data on the multi-trans-generational effects of PFAS, with a focus on their impact on the thyroid axis. The aim is to determine if there is evidence of potential multi-trans-generational effects of PFAS on the thyroid and/or if more research is needed.

EXPERT OPINION

PFAS exposure impacts thyroid homeostasis and can cross the placental barrier. In addition PFAS have shown multi-transgenerational effects in laboratory experiences and animal models, but thyroid disruptive effects of PFAS were also investigated only in a small number of these studies. Efforts are needed to study the adverse effects of PFAS, as not all PFAS are regulated and removal strategies are still being developed.

Kidney function decline mediates the adverse effects of per- and poly-fluoroalkyl substances (PFAS) on uric acid levels and hyperuricemia risk

Previous studies indicated per- and poly-fluoroalkyl substances (PFAS) were related to uric acid and hyperuricemia risk, but evidence for the exposure-response (E-R) curves and combined effect of PFAS mixture is limited. Moreover, the potential mediation effect of kidney function was not assessed. Hence, we conducted a national cross-sectional study involving 13,979 US adults in NHANES 2003-2018 to examine the associations of serum PFAS with uric acid and hyperuricemia risk, and the mediation effects of kidney function. Generalized linear models and E-R curves showed positive associations of individual PFAS with uric acid and hyperuricemia risk, and nearly linear E-R curves indicated no safe threshold for PFAS. Weighted quantile sum regression found positive associations of PFAS mixture with uric acid and hyperuricemia risk, and PFOA was the dominant contributor to the adverse effect of PFAS on uric acid and hyperuricemia risk. Causal mediation analysis indicated significant mediation effects of kidney function decline in the associations of PFAS with uric acid and hyperuricemia risk, with the mediated proportion ranging from 19 % to 57 %. Our findings suggested that PFAS, especially PFOA, may cause increased uric acid and hyperuricemia risk increase even at low levels, and kidney function decline plays a crucial mediation effect.

Investigating the progression of preeclampsia through a comprehensive analysis of genes associated with per- and polyfluoroalkyl substances

Per- and Polyfluoroalkyl Substances (PFAS) are synthetic chemicals utilized in the production of various products that possess water and dirt-repellent properties. Exposure to PFAS has been linked to numerous diseases, such as cancer and preeclampsia (PE). However, whether PFAS contributes to the advancement of PE remains uncertain. In this study, we conducted an extensive bioinformatics analysis using the Comparative Toxicogenomics Database (CTD) and Gene Expression Omnibus (GEO) databases, leading us to discover a connection between PE and four specific PFAS. Moreover, further examination revealed that six genes associated with PFAS exhibited significant diagnostic potential for individuals with PE. By employing receiver operating characteristic (ROC) curves, our PFAS-related gene-based nomogram model demonstrated outstanding predictive efficacy for diagnosing PE. Immune infiltration analysis showed that six PFAS-related genes were significantly associated with the level of immune cell infiltration. The expression of PFAS-related genes in PE patients was confirmed by collecting clinical samples. This research has offered fresh perspectives on comprehending the impact of PFAS on PE, drawing attention to the connection between environmental factors and the risks and development of PE.

Evidence of promoting effects of 6:2 Cl-PFESA on hepatocellular carcinoma proliferation in humans: An ideal alternative for PFOS in terms of environmental health?

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are synthetic chemicals, encompassing compounds like perfluorooctane sulfonate (PFOS), which have widespread applications across various industries, including food packaging and firefighting. In recent years, China has increasingly employed 6:2 Cl-PFESA as an alternative to PFOS. Although the association between PFAS exposure and hepatocellular carcinoma (HCC) has been demonstrated, the underlying mechanisms that promote HCC proliferation are uncleared. Therefore, we aimed to investigate the effects and differences of PFOS and 6:2 Cl-PFESA on HCC proliferation through in vivo and in vitro tumor models. Our results reveal that both PFOS and 6:2 Cl-PFESA significantly contribute to HCC proliferation in vitro and in vivo. Exposure led to reduced population doubling times, enlarged cell colony sizes, enhanced DNA synthesis efficiency, and a higher proportion of cells undergoing mitosis. Furthermore, both PFOS and 6:2 Cl-PFES) have been shown to activate the PI3K/AKT/mTOR signaling pathway and inhibit necroptosis. This action consequently enhances the proliferation of HCC cells. Our phenotypic assay findings suggest that the tumorigenic potential of 6:2 Cl-PFESA surpasses that of PFOS; in a subcutaneous tumor model using nude mice, the mean tumor weight for the 6:2 Cl-PFESA-treated cohort was 2.33 times that observed in the PFOS cohort (p < 0.01). Despite 6:2 Cl-PFESA being considered a safer substitute for PFOS, the pronounced effects of this chemical on HCC cell growth warrant a thorough assessment of hepatotoxicity risks linked to its usage.

Mixtures of per- and polyfluoroalkyl substances (PFAS) alter sperm methylation and long-term reprogramming of offspring liver and fat transcriptome

Male fertility has been declining worldwide especially in countries with high levels of endocrine disrupting chemicals (EDCs). Per- and polyfluorinated alkyl Substances (PFAS) have been classified as EDCs and have been linked to adverse male reproductive health. The mechanisms of these associations and their implications on offspring health remain unknown. The aims of the current study were to assess the effect of PFAS mixtures on the sperm methylome and transcriptional changes in offspring metabolic tissues (i.e., liver and fat). C57BL/6 male mice were exposed to a mixture of PFAS (PFOS, PFOA, PFNA, PFHxS, Genx; 20 µg/L each) for 18-weeks or water as a control. Genome-wide methylation was assessed on F0 epidydimal sperm using reduced representation bisulfite sequencing (RRBS) and Illumina mouse methylation array, while gene expression was assessed by bulk RNA sequencing in 8-week-old offspring derived from unexposed females. PFAS mixtures resulted in 2,861 (RRBS) and 83 (Illumina) sperm DMRs (q < 0.05). Functional enrichment revealed that PFAS-induced sperm DMRs were associated with behavior and developmental pathways in RRBS, while Illumina DMRs were related to lipid metabolism and cell signaling. Additionally, PFAS mixtures resulted in 40 and 53 differentially expressed genes (DEGs) in the liver and fat of males, and 9 and 31 DEGs in females, respectively. Functional enrichment of DEGs revealed alterations in cholesterol metabolism and mitotic cell cycle regulation in the liver and myeloid leukocyte migration in fat of male offspring, while in female offspring, erythrocyte development and carbohydrate catabolism were affected in fat. Our results demonstrate that exposure to a mixture of legacy and newly emerging PFAS chemicals in adult male mice result in aberrant sperm methylation and altered gene expression of offspring liver and fat in a sex-specific manner. These data indicate that preconception PFAS exposure in males can be transmitted to affect phenotype in the next generation.

Reprogramming of DNA methylation patterns mediates perfluorooctane sulfonate-induced fetal cardiac dysplasia

Prenatal exposure to perfluorooctane sulfonate (PFOS) is associated with adverse health effects, including congenital heart disease, yet the underlying mechanisms remain elusive. Herein, we aimed to evaluate the embryotoxicity of PFOS using C57BL/6 J mice to characterize fetal heart defects after PFOS exposure, with the induction of human embryonic stem cells (hESC) into cardiomyocytes (CMs) as a model of early-stage heart development. We also performed DNA methylation analysis to clarify potential underlying mechanisms and identify targets of PFOS. Our results revealed that PFOS caused septal defects and excessive ventricular trabeculation cardiomyopathy at 5 mg/kg/day in embryonic mice and inhibited the proliferation and pluripotency of ESCs at concentrations >20 μM. Moreover, it decreased the beating rate and the population of CMs during cardiac differentiation. Decreases were observed in the abundances of NPPA+ trabecular and HEY2+ compact CMs. Additionally, DNA methyl transferases and ten-eleven translocation (TET) dioxygenases were regulated dynamically by PFOS, with TETs inhibitor treatment inducing significant decreases similar as PFOS. 850 K DNA methylation analysis combined with expression analysis revealed several potential targets of PFOS, including SORBS2, FHOD1, SLIT2, SLIT3, ADCY9, and HDAC9. In conclusion, PFOS may reprogram DNA methylation, especially demethylation, to induce cardiac toxicity, causing ventricular defects in vivo and abnormal cardiac differentiation in vitro.

Exploring the Potential Link between PFAS Exposure and Endometrial Cancer: A Review of Environmental and Sociodemographic Factors

This exploratory narrative review paper delves into the intricate interplay between per- and polyfluoroalkyl substances (PFAS) exposure, sociodemographic factors, and the influence of stressors in the context of endometrial cancer. PFAS, ubiquitous environmental contaminants notorious for their persistence in the ecosystem, have garnered attention for their potential to disrupt endocrine systems and provoke immune responses. We comprehensively examine the various sources of PFAS exposure, encompassing household items, water, air, and soil, thus shedding light on the multifaceted routes through which individuals encounter these compounds. Furthermore, we explore the influence of sociodemographic factors, such as income, education, occupation, ethnicity/race, and geographical location and their relationship to endometrial cancer risk. We also investigated the role of stress on PFAS exposure and endometrial cancer risk. The results revealed a significant impact of sociodemographic factors on both PFAS levels and endometrial cancer risk. Stress emerged as a notable contributing factor influencing PFAS exposure and the development of endometrial cancer, further emphasizing the importance of stress management practices for overall well-being. By synthesizing evidence from diverse fields, this review underscores the need for interdisciplinary research and targeted interventions to comprehensively address the complex relationship between PFAS, sociodemographic factors, stressors, and endometrial cancer.

Association between Perfluoroalkyl Substances in Follicular Fluid and Polycystic Ovary Syndrome in Infertile Women

In recent years, perfluoroalkyl substances (PFASs), a family of fluorinated organic com pounds, have garnered much attention due to their reproductive and developmental toxicity in humans. Polycystic ovary syndrome (PCOS) is a prevalent endocrine disease that affects women of reproductive age and is a significant contributor to female infertility. A previous study suggested that PFASs play a possible role in PCOS. We conducted a clinical study investigating the relationship between PCOS and PFAS in follicular fluid. A total of 73 infertile patients with PCOS and 218 controls were recruited from the International Peace Maternity and Child Health Hospital, affiliated with the Shanghai Jiao Tong University School of Medicine. The concentrations of 12 PFASs in follicular fluid samples and sex hormones in serum were measured. Correlation analysis and multiple linear regression revealed a positive relationship between perfluorooctanoic acid (PFOA) and testosterone (T) concentrations. The adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for each PFAS were estimated using multivariable logistic regression and quantile-based g-computation (QGC). The PFOA concentrations in follicular fluid were correlated with increased odds of PCOS (second vs. first quartile: OR = 3.65, 95% CI: 1.47-9.05, p = 0.005; third vs. first quartile: OR = 2.91, 95% CI: 1.17-7.26, p = 0.022; fourth vs. first quartile: OR = 3.13, 95% CI: 1.21-8.09, p = 0.019; P for trend = 0.032). This association was confirmed with QGC. Mediation analysis suggested that the mediation effect of T in association with PFOA and PCOS was not statistically significant. Our study suggests that PFOA may be a risk factor for PCOS.

Impact of Variable Water Chemistry on PFOS-Goethite Interactions: Experimental Evidence and Surface Complexation Modeling

Perfluorooctanesulfonate (PFOS) has become a major concern due to its widespread occurrence in the environment and severe toxic effects. In this study, we investigate PFOS sorption on goethite surfaces under different water chemistry conditions to understand the impact of variable groundwater chemistry. Our investigation is based on multiple lines of evidence, including (i) a series of sorption experiments with varying pH, ionic strength, and PFOS initial concentration, (ii) IR spectroscopy analysis, and (iii) surface complexation modeling. PFOS was found to bind to goethite through a strong hydrogen-bonded (HB) complex and a weaker outer-sphere complex involving Na+ coadsorption (OS-Na+). The pH and ionic strength of the solution had a nontrivial impact on the speciation and coexistence of these surface complexes. Acidic conditions and low ionic strength promoted hydrogen bonding between the sulfonate headgroup and protonated hydroxo surface sites. Higher electrolyte concentrations and pH values hindered the formation of strong hydrogen bonds upon the formation of a ternary PFOS-Na+-goethite outer-sphere complex. The findings of this study illuminate the key control of variable solution chemistry on PFOS adsorption to mineral surfaces and the importance to develop surface complexation models integrating mechanistic insights for the accurate prediction of PFOS mobility and environmental fate.

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

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

Associations of exposure to per- and polyfluoroalkyl substances mixture with the numbers of lymph nodes in colorectal cancer patients

Colorectal cancer (CRC) is widely known with a high incidence rate worldwide, but the correlation between exposure to per- and polyfluoroalkyl substances (PFAS) and the number of lymph nodes in CRC patients remains unclear. In the present study, we enrolled 305 CRC patients (122 females and 183 males) at Beijing Hospital in China. A total of 17 PFAS were detected in serum samples of these patients, and 5 PFAS with detection rates >75% were selected in this study. The CRC patients' number of metastatic lymph nodes (MLNs) and total lymph nodes (TLNs) were chosen as outcomes. Poisson regression models were used to analyze the associations between single PFAS and number of MLNs and TLNs. Quantile g-Computation models were performed to examine the joint effect of PFAS mixtures on number of MLNs and TLNs. A positive correlation between serum PFAS levels and number of MLNs was identified. For instance, the numbers of MLNs in patients with serum PFOA, PFNA, 6:2 Cl-PFESA concentrations at the 95th percentile were 27% (95% CI: 1%, 60%), 35% (95% CI: 1%, 82%), 87% (95% CI: 4%, 238%) higher compared with the threshold level. The results of Quantile g-Computation models also showed that every quantile increase in PFAS mixtures was associated with a 4.67%, (95% CI: 0.07%, 9.48%) increase in the numbers of MLNs, and PFOS dominated the effects of the mixtures. Moreover, a negative correlation between PFAS mixtures and number of TLNs in patients with no MLNs was also observed. The present study suggested that exposure to PFAS may worsen the prognosis of CRC patients. These findings could help guide future research and public health policies aimed at reducing exposure to PFAS and mitigating their potential impacts on human health.

Firefighting, per- and polyfluoroalkyl substances, and DNA methylation of genes associated with prostate cancer risk

Prostate cancer is the leading incident cancer among men in the United States. Firefighters are diagnosed with this disease at a rate 1.21 times higher than the average population. This increased risk may result from occupational exposures to many toxicants, including per- and polyfluoroalkyl substances (PFAS). This study assessed the association between firefighting as an occupation in general or PFAS serum levels, with DNA methylation. Only genomic regions previously linked to prostate cancer risk were selected for analysis: GSTP1, Alu repetitive elements, and the 8q24 chromosomal region. There were 444 male firefighters included in this study, with some analyses being conducted on fewer participants due to missingness. Statistical models were used to test associations between exposures and DNA methylation at CpG sites in the selected genomic regions. Exposure variables included proxies of cumulative firefighting exposures (incumbent versus academy status and years of firefighting experience) and biomarkers of PFAS exposures (serum concentrations of 9 PFAS). Proxies of cumulative exposures were associated with DNA methylation at 15 CpG sites and one region located within FAM83A (q-value <0.1). SbPFOA was associated with 19 CpG sites (q < 0.1), but due to low detection rates, this PFAS was modeled as detected versus not detected in serum. Overall, there is evidence that firefighting experience is associated with differential DNA methylation in prostate cancer risk loci, but this study did not find evidence that these differences are due to PFAS exposures specifically.

Insights from metabolomics and transcriptomics studies on Perfluorohexanesulfonic acid (PFHxS) exposed zebrafish embryos

Perfluorohexanesulfonic acid (PFHxS) is a short-chain perfluoroalkyl substance widely used to replace the banned perfluorooctanesulfonic acid (PFOS) in various industrial and household products. It can be found in the environment and human bodies; however, its potential toxicities are not well studied. Zebrafish have been extensively used as a model for studying toxicants, and currently, two studies have reported on the toxicity of PFHxS in zebrafish from different approaches. Ulhaq and Tse (J Hazard Mater. 2023; 457: 131722) conducted general biological experiments and applied transcriptomics to demonstrate that PFHxS at a concentration of 5 μM could affect glucose and fatty acid metabolism, leading to oxidative stress, developmental defects, and cell cycle arrest. Xu et al. (Sci Total Environ. 2023; 887: 163770) employed metabolomics and showed that concentrations of various metabolites changed after exposure to 3 and 10 μM PFHxS. As we observed a match between the metabolomics data and our biochemistry experimental findings, we integrated the two studies, which enabled us to unfold the possible mechanism of the deregulated metabolites. We identified 22 differential expressed genes (DEGs) in the tricarboxylic acid (TCA) cycle, 17 DEGs in glcyolytic process, including the critical glucokinase under the carbon metabolism. Besides, genes likes aldehyde dehydrogenases, and histone-lysine N-methyltransferases that participate in lipid peroxidation and amino metabolism respectively were spotted. Lastly, we further strengthen our discoveries by undergoing the gene set enrichment analysis. This article could provide insights into the toxicity of PFHxS, as well as prospects for environmental studies.

Legacy and emerging per- and polyfluoroalkyl substances suppress the neutrophil respiratory burst

Per- and polyfluoroalkyl substances (PFASs) are used in a multitude of processes and products, including nonstick coatings, food wrappers, and fire-fighting foams. These chemicals are environmentally-persistent, ubiquitous, and can be detected in the serum of 98% of Americans. Despite evidence that PFASs alter adaptive immunity, few studies have investigated their effects on innate immunity. The report here presents results of studies that investigated the impact of nine environmentally-relevant PFASs [e.g. perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid potassium salt (PFOS-K), perfluorononanoic acid (PFNA), perfluorohexanoic acid (PFHxA), perfluorohexane sulfonic acid (PFHxS), perfluorobutane sulfonic acid (PFBS), ammonium perfluoro(2-methyl-3-oxahexanoate) (GenX), 7H-perfluoro-4-methyl-3,6-dioxa-octane sulfonic acid (Nafion byproduct 2), and perfluoromethoxyacetic acid sodium salt (PFMOAA-Na)] on one component of the innate immune response, the neutrophil respiratory burst. The respiratory burst is a key innate immune process by which microbicidal reactive oxygen species (ROS) are rapidly induced by neutrophils in response to pathogens; defects in the respiratory burst can increase susceptibility to infection. The study here utilized larval zebrafish, a human neutrophil-like cell line, and primary human neutrophils to ascertain whether PFAS exposure inhibits ROS production in the respiratory burst. It was observed that exposure to PFHxA and GenX suppresses the respiratory burst in zebrafish larvae and a human neutrophil-like cell line. GenX also suppressed the respiratory burst in primary human neutrophils. This report is the first to demonstrate that these PFASs suppress neutrophil function and support the utility of employing zebrafish larvae and a human cell line as screening tools to identify chemicals that may suppress human immune function.

A comprehensive review on environmental pollutants and osteoporosis: Insights into molecular pathways

A significant problem that has an impact on community wellbeing is environmental pollution. Environmental pollution due to air, water, or soil pollutants might pose a severe risk to global health, necessitating intense scientific effort. Osteoporosis is a common chronic condition with substantial clinical implications on mortality, morbidity, and quality of life. It is closely linked to bone fractures. Worldwide, osteoporosis affects around 200 million people, and every year, there are almost 9 million fractures. There is evidence that certain environmental factors may increase the risk of osteoporosis in addition to traditional risk factors. It is crucial to understand the molecular mechanisms at play because there is a connection between osteoporosis and exposure to environmental pollutants such as heavy metals, air pollutants, endocrine disruptors, metal ions and trace elements. Hence, in this scoping review, we explore potential explanations for the link between pollutants and bone deterioration through deep insights into molecular pathways. Understanding and recognizing these pollutants as modifiable risk factors for osteoporosis would possibly help to enhance environmental policy thereby aiding in the improvement of bone health and improving patient quality of life.

Ecotoxicity of single and mixture of perfluoroalkyl substances (PFOS and PFOA) in soils to the earthworm Aporrectodea caliginosa

Per and polyfluoroalkyl substances (PFAS) are persistent compounds that are massively used in industry, consumer goods and fire-fighting foams. Soil contamination by PFAS is a major environmental concern, and there is a lack of knowledge on both their ecotoxicological mechanisms and the concentrations that induce adverse effects especially to non-target organisms, particularly in the case of PFAS mixtures. This study contributes to filling these gaps by assessing and modelling the effects of PFAS (in single and in mixtures for PFOS and PFOA at different environmental doses) on juvenile endogeic earthworms of a common species in European soils (Aporrectodea caliginosa) at different levels of biological organization (sub-individual and individual). The results showed for the first time combined strong ecotoxicological effects of PFAS on earthworm survival, integumental integrity, growth, sexual maturity and on genomic stability notably with the induction of DNA breaks associated with no abnormal oxidative DNA-lesion levels. Our results demonstrated significant effects at 0.3 mg kg-1 and additive effects in case of mixtures.

Environmental pollutant pre- and polyfluoroalkyl substances are associated with electrocardiogram parameters disorder in adults

Environmental pollutants exposure might disrupt cardiac function, but evidence about the associations of per- and polyfluoroalkyl substances (PFASs) exposure and cardiac conduction system remains sparse. To explore the associations between serum PFASs exposure and electrocardiogram (ECG) parameters changes in adults, we recruited 1229 participants (mean age: 55.1 years) from communities of Guangzhou, China. 13 serum PFASs with detection rate > 85% were analyzed finally. We selected 6 ECG parameters [heart rate (HR), PR interval, QRS duration, Bazett heart rate-corrected QT interval (QTc), QRS electric axis and RV5 + SV1 voltage] as outcomes. Generalized linear models (GLMs) and Bayesian kernel machine regression (BKMR) model were conducted to explore the associations of individual and joint PFASs exposure and ECG parameters changes, respectively. We detected significant associations of PFASs exposure with decreased HR, QRS duration, but with increased PR interval. For example, at the 95th percentile of 6:2 Cl-PFESA, HR and QRS duration were - 6.98 [95% confidence interval (CI): - 9.07, - 4.90] and - 6.54(95% CI: -9.05, -4.03) lower, but PR interval was 7.35 (95% CI: 3.52, 11.17) longer than those at the 25th percentile. Similarly, significant joint associations were observed in HR, PR interval and QRS duration when analyzed by BKMR model.

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

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

The role of perfluorooctane sulfonic acid (PFOS) exposure in inflammation of intestinal tissues and intestinal carcinogenesis

PFAS (per- and polyfluoroalkyl substances) are organofluorine substances that are used commercially in products like non-stick cookware, food packaging, personal care products, fire-fighting foam, etc. These chemicals have several different subtypes made of varying numbers of carbon and fluorine atoms. PFAS substances that have longer carbon chains, such as PFOS (perfluorooctane sulfonic acid), can potentially pose a significant public health risk due to their ability to bioaccumulate and persist for long periods of time in the body and the environment. The National Academies Report suggests there is some evidence of PFOS exposure and gastrointestinal (GI) inflammation contributing to ulcerative colitis. Inflammatory bowel diseases such as ulcerative colitis are precursors to colorectal cancer. However, evidence about the association between PFOS and colorectal cancer is limited and has shown contradictory findings. This review provides an overview of population and preclinical studies on PFOS exposure and GI inflammation, metabolism, immune responses, and carcinogenesis. It also highlights some mitigation approaches to reduce the harmful effects of PFOS on GI tract and discusses the dietary strategies, such as an increase in soluble fiber intake, to reduce PFOS-induced alterations in cellular lipid metabolism. More importantly, this review demonstrates the urgent need to better understand the relationship between PFOS and GI pathology and carcinogenesis, which will enable development of better approaches for interventions in populations exposed to high levels of PFAS, and in particular to PFOS.

Per- and Polyfluoroalkyl Substances (PFAS) and Lipid Trajectories in Women 45-56 Years of Age: The Study of Women's Health Across the Nation

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are associated with less favorable blood lipid profiles in epidemiological studies. However, little is known about the potential role of PFAS in longitudinal changes in lipids among midlife women even though women become more susceptible to metabolic alterations during the menopausal transition.

OBJECTIVES

To examine associations of serum PFAS concentrations with longitudinal trajectories of blood total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides in midlife women undergoing menopausal transition.

METHODS

The sample included 1,130 women from the Study of Women's Health Across the Nation 45-56 y of age at baseline (1999-2000). We measured serum PFAS concentrations including linear perfluorooctanoic acid (n-PFOA), perfluorononanoic acid (PFNA), linear and branched perfluorooctanesulfonic acid (n-PFOS and Sm-PFOS, respectively), and perfluorohexanesulfonic acid (PFHxS) at baseline. We used k-means clustering to identify subgroups with different patterns of PFAS mixture. Blood lipids were measured annually or biannually through 2016 with an average follow-up of 14.8 y. We identified longitudinal trajectories of each lipid using latent class growth models. We used multinomial log-linear models adjusted for covariates to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of lipid trajectory classes by PFAS and their mixtures.

RESULTS

Three distinct trajectories (low, middle, high) of total, LDL, and HDL cholesterol and two distinct trajectories (low and high) of triglycerides were identified. n-PFOS, Sm-PFOS, and PFHxS were positively associated with total and LDL cholesterol trajectories. n-PFOS was inversely associated with triglycerides trajectories. PFAS mixtures (high vs. low) showed positive associations with total and LDL cholesterol trajectories (high vs. low), showing ORs (95% CIs) of 1.69 (95% CI: 1.36, 2.12) and 1.79 (95% CI: 1.44, 2.22), respectively.

DISCUSSION

Concentrations of serum PFAS were positively associated with trajectories of total and LDL cholesterol, providing a line of evidence supporting adverse effects of PFAS on lipid homeostasis. https://doi.org/10.1289/EHP12351.

Association between perfluoroalkyl and polyfluoroalkyl internal exposure and serum α-Klotho levels in middle-old aged participants

Purpose

Exposure to perfluoroalkyl and polyfluoroalkyl substances causes oxidative stress, which is strongly associated with adverse health effects. Klotho protein plays an anti-aging role via antioxidation activity.

Methods

We investigated the levels of serum α-Klotho and PFAS exposure in adults who participated in the National Health and Nutrition Examination Survey from 2013 to 2016. A nationally representative subsample of 1,499 adults aged 40-79 years was analyzed for the associations of serum α-Klotho levels with serum PFAS exposures by correlation analysis and multiple general linear models. Of note, the potential confounding factors including age and gender were adjusted. Quantile-based g-computation models were used to assess the effects of mixed PFAS exposure on serum α-Klotho levels.

Results

The weighted geometric mean of serum α-Klotho was 791.38 pg/mL for the subjects during 2013-2016. After adjusting for potential confounders, serum Klotho levels showed a statistically significant downward trend with increasing quartiles of PFOA and PFNA. Multivariate adjusted general linear regression analysis showed that increased exposure to PFNA was substantially associated with lower serum levels of α-Klotho, and each 1-unit increase in PFNA concentration was accompanied by a 20.23 pg/mL decrease in α-Klotho level; while no significant association was observed between other PFAS exposures and serum α-Klotho levels. It was negatively correlated between α-Klotho and Q4 for PFNA relative to the lowest quartile (Q1) of exposure (P = 0.025). It was found that the strongest negative correlation between PFNA exposure and serum α-Klotho levels was in the middle-aged (40-59 years) female participants. Furthermore, the mixture of the four PFAS substances showed an overall inverse association with serum α-Klotho concentrations, with PFNA being the major contributor.

Conclusions

Taken together, in a representative sample of the U.S. middle-aged and elderly populations, serum concentrations of PFAS, especially PFNA, have been negatively associated with serum levels of α-Klotho, which is strongly associated with cognition and aging. It was important to note that the majority of associations were limited to middle-aged women. It will be meaningful to clarify the causal relationship and the pathogenic mechanisms of PFAS exposure and α-Klotho levels, which is helpful to aging and aging-related diseases.

PFASs: What can we learn from the European Human Biomonitoring Initiative HBM4EU

Per- and polyfluoroalkyl substances (PFASs) were one of the priority substance groups selected which have been investigated under the ambitious European Joint programme HBM4EU (2017-2022). In order to answer policy relevant questions concerning exposure and health effects of PFASs in Europe several activities were developed under HBM4EU namely i) synthesis of HBM data generated in Europe prior to HBM4EU by developing new platforms, ii) development of a Quality Assurance/Quality Control Program covering 12 biomarkers of PFASs, iii) aligned and harmonized human biomonitoring studies of PFASs. In addition, some cohort studies (on mother-child exposure, occupational exposure to hexavalent chromium) were initiated, and literature researches on risk assessment of mixtures of PFAS, health effects and effect biomarkers were performed. The HBM4EU Aligned Studies have generated internal exposure reference levels for 12 PFASs in 1957 European teenagers aged 12-18 years. The results showed that serum levels of 14.3% of the teenagers exceeded 6.9 μg/L PFASs, which corresponds to the EFSA guideline value for a tolerable weekly intake (TWI) of 4.4 ng/kg for some of the investigated PFASs (PFOA, PFOS, PFNA and PFHxS). In Northern and Western Europe, 24% of teenagers exceeded this level. The most relevant sources of exposure identified were drinking water and some foods (fish, eggs, offal and locally produced foods). HBM4EU occupational studies also revealed very high levels of PFASs exposure in workers (P95: 192 μg/L in chrome plating facilities), highlighting the importance of monitoring PFASs exposure in specific workplaces. In addition, environmental contaminated hotspots causing high exposure to the population were identified. In conclusion, the frequent and high PFASs exposure evidenced by HBM4EU strongly suggests the need to take all possible measures to prevent further contamination of the European population, in addition to adopting remediation measures in hotspot areas, to protect human health and the environment. HBM4EU findings also support the restriction of the whole group of PFASs. Further, research and definition for additional toxicological dose-effect relationship values for more PFASs compounds is needed.

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.

Firefighters' exposure to per-and polyfluoroalkyl substances (PFAS) as an occupational hazard: A review

The term "firefighter" and "cancer" have become so intertwined in the past decade that they are now nearly inseparable. Occupational exposure of firefighters to carcinogenic chemicals may increase their risk of developing different types of cancer. PFAS are one of the major classes of carcinogenic chemicals that firefighters are exposed to as occupational hazard. Elevated levels of PFAS have been observed in firefighters' blood serum in recent studies. Possible sources of occupational exposure to PFAS include turnout gear, aqueous film-forming foam, and air and dust at both the fire scene and fire station. Preliminary discussion on PFAS includes definition, classification, and chemical structure. The review is then followed by identifying the sources of PFAS that firefighters may encounter as an occupational hazard. The structural properties of the PFAS used in identified sources, their degradation, and exposure pathways are reviewed. The elevated level of PFAS in the blood serum and how this might associate with an increased risk of cancer is discussed. Our review shows a significant amount of PFAS on turnout gear and their migration to untreated layers, and how turnout gear itself might be a potential source of PFAS exposure. PFAS from aqueous film-forming foams (AFFF), air, and dust of fire stations have been already established as potential exposure sources. Studies on firefighters' cancer suggest that firefighters have a higher cancer risk compared to the general population. This review suggests that increased exposure to PFAS as an occupational hazard could be a potential cancer risk for firefighters.

Epigenotoxicity: a danger to the future life

Environmental toxicants can regulate gene expression in the absence of DNA mutations via epigenetic mechanisms such as DNA methylation, histone modifications, and non-coding RNAs' (ncRNAs). Here, all three epigenetic modifications for seven important categories of diseases and the impact of eleven main environmental factors on epigenetic modifications were discussed. Epigenetic-related mechanisms are among the factors that could explain the root cause of a wide range of common diseases. Its overall impression on the development of diseases can help us diagnose and treat diseases, and besides, predict transgenerational and intergenerational effects. This comprehensive article attempted to address the relationship between environmental factors and epigenetic modifications that cause diseases in different categories. The studies main gap is that the precise role of environmentally-induced epigenetic alterations in the etiology of the disorders is unknown; thus, still more well-designed researches need to be accomplished to fill this gap. The present review aimed to first summarize the adverse effect of certain chemicals on the epigenome that may involve in the onset of particular disease based on in vitro and in vivo models. Subsequently, the possible adverse epigenetic changes that can lead to many human diseases were discussed.

What Happens In Utero Does Not Stay In Utero: a Review of Evidence for Prenatal Epigenetic Programming by Per- and Polyfluoroalkyl Substances (PFAS) in Infants, Children, and Adolescents

PURPOSE OF REVIEW

Review human literature on the relationship between prenatal exposure to per- and polyfluoroalkyl substances (PFAS) and epigenetic modifications in infants, children, and adolescents < 18 years of age.

RECENT FINDINGS

Eleven studies were identified, with study populations located in the U.S., Taiwan, Japan, and the Kingdom of Denmark. Many studies (n = 5) were cross-sectional, with PFAS exposure and epigenetic outcomes measured in the same tissue collected at delivery via cord blood or dried newborn blood spots. The other six studies were prospective, with prenatal PFAS measured on maternal blood during pregnancy and DNA methylation (DNAm) assessed in cord blood and childhood peripheral leukocytes (n = 1 study). Epigenetic marks of interest included global DNAm measures (LINE-1, Alu, and an ELISA-based method), candidate genes (IFG2, H19, and MEST), and epigenome-wide DNA methylation via array-based methods (Infinium 450 K and EPIC). Two studies using array-based methods employed discovery and validation paradigms, in which a small subset of loci (n = 6 and n = 4) were replicated in the discovery population. One site (TNXB) was a hit in two independent studies. Collectively, loci associated with PFAS were in regions involved in growth and development, lipid metabolism, and nutrient metabolism. There is moderate human evidence supporting associations of prenatal PFAS exposure on DNAm at birth, with one study suggesting sustained effects into childhood. Future studies are warranted to link PFAS-associated DNAm to health outcomes, as well as to investigate the role of other epigenetic marks such as hydroxymethylation, miRNA expression, and histone modifications.

Impacts of PFOAC8, GenXC6, and their mixtures on zebrafish developmental toxicity and gene expression provide insight about tumor-related disease

Concerns about per- and polyfluoroalkyl substances (PFASs) have grown in importance in the fields of ecotoxicology and public health. This study aims to compare the potential effects of long-chain (carbon atoms ≥ 7) and short-chain derivatives and their mixtures' exposure according to PFASs-exposed (1, 2, 5, 10, and 20 mg/L) zebrafish's (Danio rerio) toxic effects and their differential gene expression. Here, PFOA_C8, GenX_C6, and their mixtures (v/v, 1:1) could reduce embryo hatchability and increase teratogenicity and mortality. The toxicity of PFOA_C8 was higher than that of GenX_C6, and the toxicity of their mixtures was irregular. Their exposure (2 mg/L) caused zebrafish ventricular edema, malformation of the spine, blood accumulation, or developmental delay. In addition, all of them had significant differences in gene expression. PFOA_C8 exposure causes overall genetic changes, and the pathways of this transformation were autophagy and apoptosis. More importantly, in order to protect cells from PFOA_C8, GenX_C6, and their mixtures' influences, zebrafish inhibited the expression of ATPase and Ca²⁺ transport gene (atp1b2b), mitochondrial function-related regulatory genes (mt-co2, mt-co3, and mt-cyb), and tumor or carcinogenic cell proliferation genes (laptm4b and ctsbb). Overall, PFOA_C8, GenX_C6, and their mixtures' exposures will affect the gene expression effects of zebrafish embryos, indicating that PFASs may pose a potential threat to aquatic biological safety. These results showed that the relevant genes in zebrafish that were inhibited by PFASs exposure were related to tumorigenesis. Therefore, the effect of PFASs on zebrafish can be further used to study the pathogenesis of tumors.

Gestational exposure to perfluoroalkyl substances is associated with placental DNA methylation and birth size

DNA methylation is one potential mechanism for the effects of gestational exposure to perfluoroalkyl substances (PFASs) on fetal growth. We investigated 180 pregnant women who participated in a cohort study conducted in Tangshan City, Northern China, and determined the concentrations of 11 PFASs and the methylation of two genes related to fetal growth [insulin-like growth factor 2 (IGF2) and nuclear receptor subfamily 3 group C member 1 (NR3C1)] and one surrogate marker for global methylation [long interspersed nuclear element-1 (LINE-1)] in placenta tissue. Multiple linear regression analysis was performed to examine the associations of log transformed PFASs with the DNA methylation and birth size. Weighted quantile sum regression was used to determine the mixture effect of PFASs. After adjusting for potential confounders, perfluorooctane sulfonate (PFOS) was negatively associated with the overall methylation of LINE-1. PFASs mixture was negatively associated with the methylation of all CpG loci of LINE-1 and overall methylation of NR3C1. Perfluorootanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and the PFASs mixture showed negative associations with head circumference. After stratified by newborns' sex, PFOA, PFNA and the PFASs mixture was negatively associated with overall methylation of LINE-1 only in the male subgroup and the methylation of all CpG loci of LINE-1 was negatively associated with ponderal index only in the female subgroup. The interaction of newborns' sex with PFOS and PFOA on overall methylation of IGF2 was statistically significant and so was the interaction of sex with PFOS on overall methylation of LINE-1. These findings suggested that intrauterine exposure to PFASs affected placental DNA methylation and reduced fetal growth, which might be modified by sex.

Association between per- and polyfluoroalkyl substances and semen quality

Some studies have suggested that perfluoroalkyl and polyfluoroalkyl substance (PFAS) exposure may be associated with semen quality in the general population, but with inconsistent results. To identify a more precise relationship between them, a meta-analysis was performed. We searched Embase, the PubMed, The Cochrane Library, Ovid databases, and Web of Science databases (before March 2022) for appropriate studies on the correlations of PFAS exposure with semen parameters. We extracted β value and 95% confidence intervals (CIs) to conduct meta-analysis. Subgroup analyses was performed by sample size, geographic location, and sample type. A total of seven articles involving 2190 participants were included in this study. The concentrations of perfluorooctanoic acid (PFOA) (β value =  - 1.38; 95% CI: - 2.44, - 0.32) and perfluorononanoic acid (PFNA) (β value =  - 1.31, 95% CI: - 2.35, - 0.26) were negatively associated with sperm progressive motility. Subgroup analysis revealed that PFNA exposure was related to sperm morphology in studies with the sample size exceeding 200 people (β value =  - 0.14; 95% CI: - 0.26, - 0.01). Our study supports that exposure to some PFASs (e.g., PFNA, PFOA) may be associated with semen quality, such as lower sperm progressive motility. Therefore, it is of great significance for the prevention of male infertility by control the use of PFASs.

Effect of pretreatment with a synbiotic on Perfluorooctanoic acid-induced liver damage after sub-acute oral exposure in C57BL/6J mice

BACKGROUND

Perfluorooctanoic acid (PFOA(is used in several industrial applications, and serves as a surfactant. It is persistent in the environment and is resistant to typical environmental degradation processes. Exposure to this contaminant has been shown to reduce the normal gastrointestinal flora, especially Lactobacillus and Bifidobacterium. Since exposure to this contaminant still occurs and it has been suggested that gut microbiota imbalance might accelerate the progression of liver disorders, we aimed to study the effect of synbiotics pretreatment on PFOA-induced hepatotoxicity.

METHOD AND MATERIALS

Herein, C57BL/6 J mice were administered 1, 5, 10, and 20 mg PFOA per kg body weight orally by gavage once daily up to 28 days. Another group was pretreated with synbiotic 4 h before receiving 10 mg PFOA/kg. Also, a control group received 2% Tween 80 orally as a vehicle of PFOA during the study. Plasma ALT, AST, TNF-α, HGF, IL-6, and IFN-γ were measured every week. In addition, a liver histopathological assessment was performed at the end of exposure studies.

RESULTS

It was observed that exposure to PFOA can trigger inflammatory markers such as TNF-α, HGF, IL-6, and IFN-γ as well as hepatic enzymes AST and ALT in comparison with the control group. Synbiotic pretreatment prevented or statistically significant reduced the release of the inflammatory markers and the liver enzymes compared to PFOA only treated group.

CONCLUSION

It could be inferred that having intact gut flora or even using synbiotic complements containing Lactobacillus, Bifidobacterium, and Streptococcus plus fructooligosaccharides as prebiotic is an appropriate strategy to reduce the negative effects of PFOA exposure.

In silico analysis decodes transthyretin (TTR) binding and thyroid disrupting effects of per- and polyfluoroalkyl substances (PFAS)

Transthyretin (TTR) is a homo-tetramer protein involved in the transport of thyroid hormone (thyroxine; T4) in the plasma and cerebrospinal fluid. Many pollutants have been shown to bind to TTR, which could be alarming as disruption in the thyroid hormone system can lead to several physiological problems. It is also indicated that the monomerization of tetramer and destabilization of monomer can lead to amyloidogenesis. Many compounds are identified that can bind to tetramer and stabilize the tetramer leading to the inhibition of amyloid fibril formation. Other compounds are known to bind tetramer and induce amyloid fibril formation. Among the pollutants, per- and polyfluoroalkyl substances (PFAS) are known to disrupt the thyroid hormone system. The molecular mechanisms of thyroid hormone disruption could be diverse, as some are known to bind with thyroid hormone receptors, and others can bind to membrane transporters. Binding to TTR could also be one of the important pathways to alter thyroid signaling. However, the molecular interactions that drive thyroid-disrupting effects of long-chain and short-chain PFASs are not comprehensively understood at the molecular level. In this study, using a computational approach, we show that carbon chain length and functional group in PFASs are structural determinants, in which longer carbon chains of PFASs and sulfur-containing PFASs favor stronger interactions with TTR than their shorter-chained counterparts. Interestingly, short-chain PFAS also showed strong binding capacity, and the interaction energy for some was as close to the longer-chain PFAS. This suggests that short-chain PFASs are not completely safe, and their use and build-up in the environment should be carefully regulated. Of note, TTR homologs analysis suggests that thyroid-disrupting effects of PFASs could be most likely translated to TTR-like proteins and other species.

Plasma PFOA and PFOS Levels, DNA Methylation, and Blood Lipid Levels: A Pilot Study

Exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) is associated with blood lipids in adults, but the underlying mechanisms remain unclear. This pilot study aimed to investigate the associations between PFOA or PFOS and epigenome-wide DNA methylation and assess the mediating effect of DNA methylation on the PFOA/PFOS-blood lipid association. We measured plasma PFOA/PFOS and leukocyte DNA methylation in 98 patients enrolled from the hospital between October 2018 and August 2019. The median plasma PFOA/PFOS levels were 0.85 and 2.29 ng/mL. Plasma PFOA and PFOS levels were significantly associated with elevated total cholesterol (TC) and low-density lipoprotein cholesterol (LDL) levels. There were 63/87 CpG positions and 8/11 differentially methylated regions (DMRs) associated with plasma PFOA/PFOS levels, respectively. In addition, 5 CpG positions (annotated to AFF3, CREB5, NRG2, USF2, and intergenic region) and one DMR annotated to IRF6 may mediate the association between plasma PFOA/PFOS and LDL levels (mediated proportion from 7.29 to 46.77%); two CpG positions may mediate the association between plasma PFOA/PFOS and TC levels (annotated to CREB5 and USF2, mediated proportion is around 30%). The data suggest that PFOA/PFOS exposure alters DNA methylation. More importantly, the association of PFOA/PFOS with lipid indicators was partly mediated by DNA methylation changes in lipid metabolism-related genes.

Perfluorooctanoic acid-induced developmental cardiotoxicity in chicken embryo: Roles of miR-490-5p

Perfluorooctanoic acid (PFOA) could induce developmental toxicities, affecting various organs, including the heart. Although peroxisome-proliferation activated receptor alpha (PPARα) had been identified as a major target of PFOA, PPARα-independent effects are frequently reported. To further elucidate the mechanism of toxicity in PFOA-induced developmental cardiotoxicity, RNA-seq analysis was performed in hatchling chicken hearts developmentally exposed to vehicle or 2 mg/kg (egg weight) PFOA. RT-PCR and western blotting were then performed to confirm the identified potential targets. Furthermore, lentivirus was designed to overexpress and silence identified target miRNA in developing chicken embryo, and the resulting phenotypes were investigated. 21 miRNAs and 1142 mRNAs were identified to be affected by developmental exposure to PFOA in chicken embryo hearts. Among the identified differentially expressed miRNAs, miR-490-5p was confirmed to be significantly affected by PFOA exposure, along with its downstream targets, Synaptosome associated protein 91 (SNAP91) and LY6/PLAUR domain containing 6 (LYPD6), as indicated by RT-PCR and western blotting results. Lentivirus overexpressing miR-490-5p mimicked the phenotype induced by PFOA exposure, while lentivirus silencing miR-490-5p alleviated PFOA-induced changes. Similar patterns were also observed in the expression of downstream target genes, SNAP91 and LYPD6. In summary, miR-490-5p and its downstream genes, SNAP91 and LYPD6 are associated with PFOA-induced developmental cardiotoxicity in chicken embryo, which might help to further elucidate the mechanism of PFOA-induced developmental cardiotoxicity.