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

Female-specific associations of serum perfluoroalkyl and polyfluoroalkyl substances with sex hormonal/insulin dysregulation: An integrated population-based study

BACKGROUND

Ubiquitous perfluoroalkyl/polyfluoroalkyl substances (PFASs) exhibit sex-differential blood accumulation. However, sex- and age-specific links between PFASs and insulin-hormone dysregulation remain unknown.

METHODS

This population-based study utilized survey-weighted data from the National Health and Nutrition Examination Survey 2013-2016. Correlations between PFASs and sex hormone- or insulin-related indicators were assessed using a survey-weighted generalized linear model (SWGLM) for individual analyses and weighted quantile sum (WQS) regression for mixture analyses, stratified by sex and age. The mixture-related findings were validated with Bayesian kernel machine regression (BKMR) and further examined through stratification by menopausal status. Moreover, we investigated whether homeostatic model assessment of insulin resistance (HOMA-IR) mediated the relationships between sex hormones and monomethyl branched isomers of perfluorooctane sulfonate (Sm-PFOS) sex-specifically.

RESULTS

The following results persisted only in females. In SWGLM, linear perfluorooctanoate (n-PFOA) and homeostatic model assessment of β cell function (HOMA-β) were positively correlated in females, with this correlation strengthening in those aged ≥ 60. In WQS, PFAS mixture was positively associated with total testosterone/estradiol (TT/E2) and negatively associated with estradiol (E2) in females, but not in postmenopausal participants; the BKMR demonstrated trends consistent with prior findings. These associations intensified in females aged 20-59, with n-PFOA and perfluorohexane sulfonic acid (PFHxS) being main pollutants in the 20-39 and 40-59 age groups, respectively in WQS. The relationships between Sm-PFOS and both free androgen index and sex hormone-binding globulin (SHBG) were mediated by HOMA-IR.

CONCLUSIONS

This cross-sectional study reveals female-specific associations between PFASs and insulin-hormone imbalance, suggesting multifaceted influences of PFASs on female endocrinology.

Deciphering per- and polyfluoroalkyl substances mode of action: comparative gene expression analysis in human liver spheroids

Understanding the mechanisms by which environmental chemicals cause toxicity is necessary for effective human health risk assessment. High-throughput transcriptomics (HTTr) can be used to inform risk assessment on toxicological mechanisms, hazards, and potencies. We applied HTTr to elucidate the molecular mechanisms by which per- and polyfluoroalkyl substances (PFAS) cause liver perturbations. We contrasted transcriptomic profiles of PFOA, PFBS, PFOS, and PFDS against transcriptomic profiles from established liver-toxic and non-toxic reference compounds, alongside peroxisome proliferator-activated receptors (PPARs) agonists. Our analysis was conducted on metabolically competent 3-D human liver spheroids produced from primary cells from 10 donors. Pathway analysis showed that PFOS and PFDS perturb many of the same pathways as the known liver-toxic compounds in the spheroids, and that the cholesterol biosynthesis pathways are significantly affected by exposure to these compounds. PFOA alters lipid metabolism-related pathways but its expression profile does not closely match reference compounds. PFBS upregulates many degradation-related pathways and targets many of the same pathways as the PPAR agonists and acetaminophen. Our transcriptional analysis does not support the claim that these PFAS are DNA-damaging in this model. A multidimensional scaling (MDS) analysis revealed that PFOS, PFOA, and PFDS cluster together in the same multidimensional space as liver-damaging compounds, whereas PFBS clusters more closely with the non-liver-damaging compounds. Benchmark concentration-response modeling predicts that all the PFAS are bioactive in the liver. Overall, our results show that these PFAS produce unique transcriptional changes but also alter pathways associated with established liver-toxic chemicals in this liver spheroid model.

Effects of mixed exposure to PFAS on adolescent non-alcoholic fatty liver disease: Integrating evidence from human cohorts, toxicogenomics, and animal models to uncover mechanisms and potential target sites

Extensive evidence suggests a correlation between environmental pollutants, specifically perfluoroalkyl and polyfluoroalkyl substances (PFAS) and non-alcoholic fatty liver disease (NAFLD). This study aims to investigate the association and underlying mechanisms of PFAS-induced NAFLD in adolescents by employing a comprehensive approach of population-based studies, toxicogenomics, and animal models. A total of 2014 freshmen from Dali University were recruited for this study, with 1694 participants undergoing serum testing for PFAS exposure. Additionally, Comparative Toxicogenomics Database analysis and PFAS exposure experiments were conducted by orally administering PFAS to 8-week-old adult C57/6 J mice for 28 days. Epidemiological analysis of the adolescent cohort revealed that perfluorohexanesulfonic acid and perfluorooctanoic acid are significant risk factors for NAFLD in adolescents. Toxicogenomic analysis revealed that the negative regulation of gap junction assembly and glutathione derivative biosynthesis contributes to NAFLD development. Animal model studies further demonstrated that combined PFAS exposure led to pathological changes in hepatocytes, including inflammation and steatosis, elevated liver enzymes, cholestasis, and bile canalicular blockage. This study reveals that PFAS exposure serves as a significant risk factor for hepatic steatosis/NAFLD in adolescents. The activation of cytochrome P4502E1 and glutathione S-transferase A1 signaling highlights new molecular targets for PFAS-induced disruptions in hepatic lipid metabolism.

Development, optimization and validation of a highly sensitive and selective method for the determination of PFAS in animal-based food

Perfluorocarboxylic acids and perfluorosulfonic acids accumulate in food webs, thus posing a serious threat to food safety. The European Food Safety Authority (EFSA) derived a tolerable weekly intake (TWI) of 4.4 ng/kg body weight for the sum of the four so-called EFSA-PFAS in 2020. More sensitive analytical methods are urgently needed, not only to monitor maximum levels, but also for future toxicological assessments of these substances. Therefore, in the present study a dual SPE approach for the purification of the extracts was chosen to attain high and valid sensitivity for the matrices egg, liver, milk and dairy products using liquid chromatography coupled with tandem mass spectrometry. This method achieved limits of quantification of 2.60 (PFOS) - 6.80 ng/kg (PFHxS) for egg, 9.80 (PFOS) - 46.0 ng/kg (PFHxS) for liver and 0.165 (PFNA) - 0.455 ng/kg (PFOS) for milk for the 4 EFSA-PFAS. Summed medians for the 4 EFSA-PFAS of 396 ng/kg in bovine liver and 54.0 ng/kg in pork liver, as well as 8.46 ng/kg in cheese and 4.57 ng/kg in milk were detected. The results were subjected to correlation analysis. Statistically significant strong correlations were identified between bovine and porcine liver for PFNA, PFDA, PFUnDA and PFOS. To summarize the PFAS content and the PFAS spectrum detected depend on the animal species examined. Furthermore, an estimation of the exhaustion of the TWI for children, women and men was conducted. In our model, a TWI exhaustion of more than 27.0% (children) was calculated for liver, milk and cheese.

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.

Preparation of Polyaniline Modified Cellulose Filter Paper and Its Application in Detecting 23 Per- and Polyfluoroalkyl Substances

Per- and polyfluoroalkyl substances (PFAS) are a widely used class of synthetic chemicals that pose a significant global environmental and health threat due to their persistent and bioaccumulation toxicity caused by strong C-F bonds in their structures. PFAS usually exist in trace concentrations in environmental water bodies, which poses great challenges for environmental analysis. In this study, environmentally friendly cellulose was modified with polyaniline through in situ oxidative polymerization, and used as the filter paper for solid-phase extracting 23 PFAS in water. Characterization techniques such as scanning electron microscope, Fourier transform infrared spectroscopy, X-ray photoelectron spectrometer, and thermogravimetric analysis indicated the successful synthesis of structurally stable polyaniline-modified cellulose filter paper (PANI/CFP). Then, a high-performance liquid chromatograph-triple quadrupole mass spectrometry determination method was established for 23 PFAS from water using PANI/CFP extraction. The optimal adsorption occurred at a solution pH of 3.0-5.0, and the best elution efficiency can be achieved using methanol with 2% added ammonia water. The adsorption mechanism of 23 PFAS by PANI/CFP can be considered as the result of synergistic effects between physical and chemical adsorption. The recovery rates for 23 PFAS in groundwater, surface water, and wastewater ranged from 65.8% to 105%, with limits of detection and quantification from 0.44 to 36.5 ng/L. After being reused five times, PANI/CFP can still maintain a good extraction recovery rate for PFAS. This study successfully prepared PANI/CFP and established an experimental method flow for its application in the extraction and detection of 23 PFAS in water. The PANI/CFP has the characteristics of stable structure and properties, and easy operation.

Kidney function mediates the association of per- and poly-fluoroalkyl substances (PFAS) and heavy metals with hepatic fibrosis risk

Heavy metals and per- and polyfluoroalkyl substances (PFAS) are significantly associated with the risk of hepatic fibrosis. However, the potential mediating effect of kidney function in the relationship between heavy metals, PFAS, and hepatic fibrosis risk remains unexplored. This research gap limits the development of hepatic fibrosis prevention and treatment strategies. To address this, this study conducts a cross-sectional analysis based on data from 10,870 participants in NHANES 2005-2018 to explore the relationship between heavy metals, PFAS, and the risk of hepatic fibrosis, as well as the mediating effect of kidney function. Participants with a Fibrosis-4 index <1.45 are defined as not having hepatic fibrosis in this study. Results from generalized linear regression models and weighted quantile sum regression models indicate that both individual and combined exposures to heavy metals and PFAS are positively associated with the risk of hepatic fibrosis. Nonlinear exposure-response functions suggest that there may be a threshold for the relationship between heavy metals (except mercury) and PFAS with the risk of hepatic fibrosis. Furthermore, heavy metals and PFAS increase the risk of kidney function impairment. After stratification by kidney function stage, the relationship between heavy metals (except lead) and proteinuria is not significant, while PFAS show a significant negative association with proteinuria. The decline in kidney function has a significant mediating effect in the relationship between heavy metals and PFAS and the risk of hepatic fibrosis, with mediation effect proportions all above 20%. The findings suggest that individual or combined exposure to heavy metals and PFAS does not increase the risk of hepatic fibrosis until a certain threshold is reached, and the mediating role of declining kidney function is very important. These results highlight the need to consider kidney function in the context of hepatic fibrosis risk assessment and management.

Kidney function mediates the effects of four per-and polyfluoroalkyl substances (PFAS) on atherosclerotic cardiovascular disease

BACKGROUND

PFAS pose a significant threat to cardiovascular health and increase the risk of atherosclerotic cardiovascular disease (ASCVD). However, there is limited research evidence regarding the mechanisms by which PFAS affect the risk of ASCVD and the exposure-risk (E-R) relationship. The effect of kidney function in the relationship between PFAS and ASCVD risk has not been adequately validated.

OBJECTIVE

This study aims to explore the mechanisms by which four PFAS (Perfluorooctanoic acid (PFOA), Perfluorooctanesulfonic acid (PFOS), Perfluorohexanesulfonic acid (PFHS), and Perfluorononanoic acid (PFNA)) affect the risk of ASCVD and to verify and discuss the mediating effect of kidney function in this impact.

METHODS

This study utilizes data from 14,607 participants in the NHANES 2005-2018 to conduct a cross-sectional study. Initially, Generalized Linear Model (GLM) and Restricted Cubic Splines models are used to assess the impact of four PFAS on ASCVD risk and the E-R relationship. Subsequently, the Weighted Quantile Sum regression (WQS) model is used to evaluate the relationship between mixed four PFAS exposure and ASCVD risk. Finally, Directed Acyclic Graphs (DAG) and causal mediation models are used to confirm and analyze whether the decline in kidney function mediates the impact of four PFAS on ASCVD risk.

RESULTS

The results from GLM and WQS models indicate that both singular and mixed four PFAS exposures are associated with an increased risk of ASCVD. The E-R curves between four PFAS singular and mixed exposures and ASCVD risk are all characterized by nonlinearity. The results from DAG and causal mediation models clearly indicate that the decline in kidney function plays a significant mediating role in the relationship between four PFAS and ASCVD risk.

CONCLUSION

Exposure levels of four PFAS do not significantly increase the risk of ASCVD unless they reach a certain threshold, and the decline in kidney function exerts a significant mediating effect in the relationship between four PFAS exposure and ASCVD risk.

Adolescent F-53B exposure induces ovarian toxicity in rats: Autophagy-apoptosis interplay

As a substitute for perfluorooctane sulfonates, F-53B has permeated into the environment and can reach the human body through the food chain. Adolescent individuals are in a critical stage of development and may be more sensitive to the impacts of F-53B. In the present study, we modeled the exposure of adolescent female rats by allowing them free access to F-53B at concentrations of 0 mg/L, 0.125 mg/L, and 6.25 mg/L in drinking water, aiming to simulate the exposure in the adolescent population. Using the ovary as the focal point, we investigated the impact of developmental exposure to F-53B on female reproduction. The results indicated that F-53B induced reproductive toxicity in adolescent female rats, including ovarian lesions, follicular dysplasia and hormonal disorders. In-depth investigations revealed that F-53B induced ovarian oxidative stress, triggering autophagy within the ovaries, and the autophagy exhibited the interplay with apoptosis in turn, collectively leading to significant ovarian toxicity. Our findings provided deeper insights into the roles of the autophagy-apoptosis interplay in ovarian toxicity, and offered a new perspective on the developmental toxicity inflicted by adolescent F-53B exposure.

Intrauterine exposure to long-chain perfluorocarboxylic acids (PFCAs) were associated with reduced primary bile acids in three-year-old children: Findings from a prospective birth cohort study

Bile acids (BAs) play a crucial role in lipid metabolism of children. However, the association between per- and polyfluoroalkyl substance (PFAS) exposure and BAs in children is scarce. To address this need, we selected 252 children from the Maoming Birth Cohort and measured 32 PFAS, encompassing short- and long-chain perfluorocarboxylic acids (PFCAs) and perfluorosulfonic acids (PFSAs) in the cord blood. Additionally, we analyzed nine primary and eight secondary BAs in the serum of three-year-old children. Generalized linear models with FDR-adjusted and Bayesian kernel machine regression (BKMR) were used to explore the associations of individual and mixture effects of PFAS and BAs. We found negative associations between cord blood long-chain PFCAs exposure and serum primary BAs in three-year-old children. For example, one ln-unit (ng/mL) increase of perfluoro-n-tridecanoic acid (PFTrDA), perfluoro-n-undecanoic acid (PFUnDA) and perfluoro-n-decanoic acid (PFDA) were associated with decreased taurochenodeoxycholic acid, with estimated percentage change of -24.28% [95% confidence interval (CI): -36.75%, -9.35%], -25.84% (95% CI: -39.67%, -8.83%), and -22.97% (95% CI: -34.45%, -9.47%) respectively. Notably, the observed associations were more pronounced in children with lower vegetable intake. Additionally, the BKMR model also demonstrated a monotonical decline in primary BAs as the PFAS mixture increased. We provided the first evidence of the association between intrauterine exposure to PFAS and its mixture with BAs in children. Further large-sample-size studies are needed to verify this finding.

PFAS exposure is associated with an unfavourable metabolic profile in infants six months of age

Exposure to perfluoroalkyl substances (PFAS) are reported to have numerous negative health effects and children are especially vulnerable. The aim of this study was to investigate whether maternal and infant PFAS burden have any impact on prenatal and postnatal growth, liver and lipid parameters in infants at age six months. Data on diet and growth parameters, as well as blood samples were collected from healthy pregnant women in week 18 and in the women and their infants at six months postpartum. The blood samples were analysed for liver enzymes, blood lipids and PFAS. Maternal perfluoroalkyl carboxylic acids (PFCA) and fish for dinner ≥ 3 days per week in pregnancy week 18 were associated with reduced birth weight and increased percent weight gain the first six months of life. Infant PFCA concentrations were positively associated with serum alanine aminotransferase and total- and LDL-cholesterol concentrations at six months of age. Our data demonstrate that prenatal and postnatal PFAS exposure are associated with an unfavourable metabolic profile at a very young age. This pattern is concerning as it may be linked to early conditioning of later metabolic disease. It is vital to reduce PFAS exposure in women of fertile age in order to prevent development of metabolic disease in the next generation.

An unbiased, sustainable, evidence-informed Universal Food Guide: a timely template for national food guides

BACKGROUND

Although national food guides are designed, ostensibly, to translate scientific evidence with respect to food, dietary patterns, and health, their development has increasingly become a corporate/political process as well as scientific one; often with corporate/political influences overriding science. Our aim was to construct an unbiased, sustainable, evidence-informed Universal Food Guide to serve as a template for countries to develop their unique guides, thereby, provide a valid resource for health professionals, health authorities, and the public.

METHODS

To address our aim, we conducted an integrative review of multiple evidence-informed sources (e.g., established databases, evidence syntheses, scholarly treatises, and policy documents) related to four areas: 1. Food guides' utility and conflicts of interest; 2. The evidence-based healthiest diet; 3. Constituents of the Universal Food Guide template; and 4. Implications for population health; regulation/governance; environment/climate/planetary health; and ethics.

RESULTS

The eating pattern that is healthiest for humans (i.e., most natural, and associated with maximal health across the life cycle; reduced non-communicable disease (NCD) risk; and minimal end-of-life illness) is whole food, low fat, plant-based, especially vegan, with the absence of ultra-processed food. Disparities in national food guide recommendations can be explained by factors other than science, specifically, corporate/political interests reflected in heavily government-subsidized, animal-sourced products; and trends toward dominance of daily consumption of processed/ultra-processed foods. Both trends have well-documented adverse consequences, i.e., NCDs and endangered environmental/planetary health. Commitment to an evidence-informed plant-based eating pattern, particularly vegan, will reduce risks/manifestations of NCDs; inform healthy food and nutrition policy regulation/governance; support sustainable environment/climate and planetary health; and is ethical with respect to 'best' evidence-based practice, and human and animal welfare.

CONCLUSION

The Universal Food Guide that serves as a template for national food guides is both urgent and timely given the well-documented health-harming influences that corporate stakeholders/politicians and advisory committees with conflicts of interest, exert on national food guides. Such influence contributes to the largely-preventable NCDs and environmental issues. Policy makers, health professionals, and the public need unbiased, scientific evidence as informed by the Universal Food Guide, to inform their recommendations and choices.

Itaconic Acid Alleviates Perfluorooctanoic Acid-Induced Oxidative Stress and Intestinal Damage by Regulating the Keap1/Nrf2/Ho-1 Pathway and Reshaping the Gut Microbiota

Itaconic acid (IA) is recognized for its potential application in treating intestinal diseases owing to the anti-inflammatory and antioxidant properties. Perfluorooctanoic acid (PFOA) can accumulate in animals and result in oxidative and inflammatory damages to multi-tissue and organ, particularly in the intestinal tract. This study aimed to explore whether IA could mitigate intestinal damage induced by PFOA exposure in laying hens and elucidate its potential underlying mechanisms. The results showed that IA improved the antioxidant capacity of laying hens and alleviated the oxidative damage induced by PFOA, as evidenced by the elevated activities of T-SOD, GSH-Px, and CAT, and the decreased MDA content in both the jejunum and serum. Furthermore, IA improved the intestinal morphological and structural integrity, notably attenuating PFOA-induced villus shedding, length reduction, and microvillus thinning. IA also upregulated the mRNA expression of ZO-1, Occludin, Claudin-1, and Mucin-2 in the jejunum, thereby restoring intestinal barrier function. Compared with the PF group, IA supplementation downregulated the gene expression of Keap1 and upregulated the HO-1, NQO1, SOD1, and GPX1 expression in the jejunum. Meanwhile, the PF + IA group exhibited lower expressions of inflammation-related genes (NF-κB, IL-1β, IFN-γ, TNF-α, and IL-6) compared to the PF group. Moreover, IA reversed the PFOA-induced imbalance in gut microbiota by reducing the harmful bacteria such as Escherichia-Shigella, Clostridium innocuum, and Ruminococcus torques, while increasing the abundance of beneficial bacteria like Lactobacillus. Correlation analysis further revealed a significant association between gut microbes, inflammatory factors, and the Keap1/Nrf2/HO-1 pathway expression. In conclusion, dietary IA supplementation could alleviate the oxidative and inflammatory damage caused by PFOA exposure in the intestinal tract by reshaping the intestinal microbiota, modulating the Keap1/Nrf2/HO-1 pathway and reducing oxidative stress and inflammatory response, thereby promoting intestinal homeostasis.

Exposure to per- and polyfluoroalkyl substances in lung cancer patients and their associations with clinical health indicators

Per- and polyfluoroalkyl substances (PFASs) have potential carcinogenicity, immunotoxicity, and hepatotoxicity. Research has been conducted on PFAS exposure in people to discuss their potential health effects, excluding lung cancer. In this study, we recruited participants (n = 282) with lung cancer from Heilongjiang Province, northeast China. The PFAS concentrations were measured in their serum to fill the data gap of exposure, and relationships were explored in levels between PFASs and clinical indicators of tumor, immune and liver function. Ten PFASs were found in over 80 % of samples and their total concentrations were 5.27-152 ng/mL, with the highest level for perfluorooctanesulfonate (median: 12.4 ng/mL). Long-chain PFASs were the main congeners and their median concentration (20.5 ng/mL) was nearly three times to that of short-chain PFASs (7.61 ng/mL). Significantly higher concentrations of perfluorobutanoic acid, perfluorononanoic acid and perfluorohexanesulfonate were found in males than in females (p < 0.05). Serum levels of neuro-specific enolase were positively associated with perfluoropentanoic acid in all participants and were negatively associated with perfluorononanesulfonate in females (p < 0.05, multiple linear regression models). Exposure to PFAS mixture was significantly positively associated with the lymphocytic absolute value (difference: 0.224, 95% CI: 0.018, 0.470; p < 0.05, quantile g-computation models) and serum total bilirubin (difference: 2.177, 95% CI: 0.0335, 4.33; p < 0.05). Moreover, PFAS exposure can affect γ-glutamyl transpeptidase through several immune markers (p < 0.05, mediating test). Our results suggest that exposure to certain PFASs could interfere with clinical indicators in lung cancer patients. To our knowledge, this is the first study to detect serum PFAS occurrence and check their associations with clinical indicators in lung cancer patients.