Association of per- and polyfluoroalkyl substance exposure with fatty liver disease risk in US adults

Association between PFAS exposure and metabolic-related biomarkers in Spanish adolescents

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) exert endocrine disruptive effects on the endocrine-metabolic axis. Emerging knowledge suggests that kisspeptin may play a key role in these effects.

OBJECTIVE

To assess the cross-sectional association of blood PFAS concentrations with kisspeptin levels, KISS1 gene DNA methylation, and metabolic-related biomarkers in adolescent males from the Spanish INMA-Granada cohort.

METHODS

Seven PFAS and twelve biomarkers (glucose-GLU, total cholesterol-TC, triglycerides, LDL, HDL, ALP, AST, ALT, GGT, total bilirubin-BILT, direct bilirubin-BILD, and urea) were measured in plasma and serum, respectively, from 129 adolescent males (15-17 yrs). Systolic and diastolic blood pressure (SBP, DBP), pulse, z-scored body mass index, kisspeptin protein levels (n = 104) and whole blood KISS1 DNA methylation (n = 117) were determined. Linear regression models, weighted quantile sum (WQS), and Bayesian kernel machine (BKMR) were fit.

RESULTS

PFHpA was associated with lower GLU levels [% change per log-unit increase in plasma concentrations (95%CI) = -4.73 (-8.98;-0.28)], and PFUnDA with higher GLU, TC, and HDL levels. In models adjusted by kisspeptin level, PFOS was associated with higher SBP [3.42 (-0.12; 7.09)]. Additionally, PFNA and total PFAS concentrations were associated with higher kisspeptin levels [3.91 (0.55; 7.37) and 6.14 (0.47; 12.13), respectively]. Mixture models showed that combined PFAS exposure was associated with higher HDL, lower hepatic biomarkers (ALT, BILD) and higher kisspeptin levels.

CONCLUSION

Certain PFAS (e.g. PFUnDA) and their mixture were associated with metabolic-related biomarkers, mainly GLU, HDL, and SBP. These associations may be influenced by kisspeptin levels. More studies are needed to verify these observations.

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.

Per- and polyfluoroalkyl substances exposures are associated with non-alcoholic fatty liver disease, particularly fibrosis

Per- and polyfluoroalkyl substances (PFAS) have been reported to exert hepatotoxic effects; however, their impact on nonalcoholic fatty liver disease (NAFLD) remains unclear. This study aimed to investigate the association between PFAS exposure and NAFLD in Korean adults, thereby contributing to the generalization of PFAS's hepatotoxic effects. Using data from the 2018-2020 Korean National Environmental Health Survey (KoNEHS), we analyzed 2635 Korean adults. PFAS exposure levels were estimated based on the serum concentrations of five PFAS. NAFLD was assessed using two steatosis-related indices (hepatic steatosis index [HSI] and fatty liver index [FLI]) and two fibrosis-related indices (fibrosis-4 index [FIB-4] and aspartate aminotransferase to platelet ratio index [APRI]). The models included these indices as continuous and dichotomous variables, the latter based on diagnostic criteria from previous studies. Associations with PFAS exposure were examined using multiple linear regression and robust Poisson regression models. Positive associations were observed between PFAS exposure and three of the four continuous indices, excluding the FLI, as well as the prevalence of NAFLD diagnosed using these indices. Specifically, the HSI showed a significant association only with perfluorononanoic acid, whereas fibrosis-related indices (FIB-4 and APRI) were significantly associated with all five individual PFAS. The associations were stronger in female and non-obese groups when stratified by sex and obesity status. The results of the Bayesian kernel machine regression analysis evaluating the health effects of PFAS mixtures indicated an association between PFAS mixtures and NAFLD, particularly fibrosis-related indices. Additionally, significant associations with NAFLD indices were mostly observed in females and non-obese groups, supporting the findings from the individual PFAS exposure analyses. Our findings suggest that PFAS are associated with NAFLD, particularly for fibrosis. Considering the high serum PFAS concentrations in the Korean population, continuous monitoring and prospective cohort studies are warranted.

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

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

Association of Per- and Polyfluoroalkyl Substance Exposure With Cataract Prevalence Among U.S. Adults: A NHANES Analysis (2005-2008)

Purpose

Cataract, a major health concern among the elderly, can be influenced by environmental exposures. This study examines the association between per- and polyfluoroalkyl substance (PFAS) exposure and cataract prevalence.

Methods

Six serum PFAS concentrations were detected among 2119 U.S. adults aged 40 years or older based on the National Health and Nutrition Examination Survey. Multivariable models, including weighted logistic regression, weighted quantile sum (WQS) regression, and Bayesian kernel machine regression, were used to assess the association between individual and overall PFAS exposure and cataract prevalence. A mediation analysis was conducted for inflammation biomarkers.

Results

Single exposure to perfluorohexane sulfonic acid (PFHS) and perfluorononanoic acid (PFNA) was found to be markedly associated with cataract prevalence after adjustment for covariates (PFHS: odds ratio [OR], 1.579; 95% CI, 1.003-2.514; PFNA: OR, 1.629; 95% CI, 1.065-2.506). The WQS index was significantly associated with cataract (OR, 1.441; 95% CI, 1.130-1.837). PFNA and PFHS were the most influential exposures in the PFAS mixture. In the Bayesian kernel machine regression model, PFNA and PFHS exhibited the highest group posterior inclusion probability, aligning with the WQS results. Moreover, serum albumin and neutrophil counts were found to mediate the relationship between PFHS and cataract, accounting for -26.20% and -5.95% of the mediation effect, respectively.

Conclusions

Exposure to PFAS was positively associated with cataract, primarily driven by PFHS and PFNA. Mediation of serum albumin and neutrophil count was observed.

Translational Relevance

This study links PFAS exposure to cataract prevalence, suggesting reducing exposure could help in cataract prevention.

Evaluating PFAS-Induced modulation of peripheral blood mononuclear cells (PBMCs) immune response to SARS-CoV-2 spike in COVID-19 Vaccinees

The persistent nature of the environmental contaminants per- and polyfluoroalkyl substances (PFAS) has recently received considerable attention, particularly because of their adverse effects on immune system functionality in the context of vaccine responses to infectious diseases. Following COVID-19 vaccination, some studies have shown a significant negative correlation between serum PFAS concentrations and the humoral immune response to the SARS-CoV-2 spike protein vaccination. However, the influence of PFAS on the cell-mediated immune response to SARS-CoV-2 spike protein post-COVID-19 vaccination remains underexplored. In the present study, we investigated the impact of a human blood-relevant PFAS mixture, containing perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonate (PFHxS), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA) on innate (monocytes and NK cells), cell-mediated (T cells) and B cells adaptive immune responses in COVID-19-vaccinated female and male healthy donors. Human peripheral blood mononuclear cells (PBMCs) were exposed to a mixture of the six PFAS at real life concentrations and subsequently stimulated with the SARS-CoV-2 spike peptide. We report a significant upregulation of IFNγ production in T and NK cells, particularly among male donors exposed to high concentrations of the PFAS mixture. Conversely, we observed a decrease in the total B-cell population, particularly among female donors. A significant reduction in the secretion of the pro-inflammatory chemokines MIP-1α (CCL3) and MIP-3α (CCL20) was observed at high PFAS mixture concentrations. Overall, these findings suggest that high PFAS exposure may differentially affect immune responses in a sex-specific manner, with a potential impact on vaccine efficacy.

Environmental Pollutants, Occupational Exposures, and Liver Disease

Environmental pollutants significantly impact liver disease development, progression, and outcomes. This review examines the complex relationship between environmental exposures and liver pathology, from malignant conditions like hepatocellular carcinoma to steatotic and cholestatic liver diseases. Key environmental factors include air pollutants, volatile organic compounds, persistent organic pollutants, heavy metals, and per- and polyfluoroalkyl substances. These compounds can act through multiple mechanisms, including endocrine disruption, metabolic perturbation, oxidative stress, and direct hepatotoxicity. The impact of these exposures is often modified by factors such as sex, diet, and genetic predisposition. Recent research has revealed that even low-level exposures to certain chemicals can significantly affect liver health, particularly when combined with other risk factors. The emergence of exposomics as a research tool promises to enhance our understanding of how environmental factors influence liver disease. Importantly, exposure effects can vary by demographic and socioeconomic factors, highlighting environmental justice concerns. Implementation of this knowledge in clinical practice requires new diagnostic approaches, healthcare system adaptations, and increased awareness among medical professionals. In conclusion, this review provides a comprehensive examination of current evidence linking environmental exposures to liver disease and discusses implications for clinical practice and public health policy.

Linear association of the dietary index for gut microbiota with insulin resistance and type 2 diabetes mellitus in U.S. adults: the mediating role of body mass index and inflammatory markers

Background

Gut microbiota is reported to be related to the onset of insulin resistance (IR) and type 2 diabetes mellitus (T2DM). The dietary index for gut microbiota (DI-GM) is a novel index for reflecting gut microbiota diversity. We aimed to evaluate the association of DI-GM with T2DM and IR.

Methods

This cross-sectional research comprised 10,600 participants aged ≥20 from the National Health and Nutrition Examination Survey (NHANES) 2007-2018. We employed weighted multivariable linear and logistic regression models to examine the correlation of DI-GM with T2DM and IR. Linear or nonlinear relationships were examined by restricted cubic spline (RCS) regression. Additionally, subgroup and sensitivity analyses were performed to ensure the reliability of the results. Mediation analysis explored the roles of body mass index (BMI) and inflammatory factors in these associations.

Results

Higher DI-GM were inversely associated with T2DM (OR = 0.93, 95%CI: 0.89-0.98) and IR (OR = 0.95, 95%CI: 0.91-0.99) after adjusting for confounders. DI-GM ≥ 6 group showed significantly lower risks of T2DM (OR = 0.74, 95%CI: 0.60-0.91) and IR (OR = 0.77, 95%CI: 0.62-0.95). RCS demonstrated a linear relationship between DI-GM and T2DM, as well as IR. DI-GM was also inversely correlated with the risk markers of T2DM. Mediation analysis showed that BMI and the systemic inflammation response index partly mediated the association of DI-GM with T2DM and IR, while the systemic immune-inflammation index mediated only the association with T2DM.

Conclusion

DI-GM is inversely associated with T2DM and IR, with BMI and inflammatory markers partly mediating this association.

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

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

Perfluorohexane Sulfonic Acid Disrupts the Immune Microenvironment for Spermatogenesis by Damaging the Structure of the Blood-Testis Barrier in Mice

Perfluorohexane sulfonic acid (PFHxS) is extensively used in waterproof coatings and fire-fighting foams, and several studies have found it to be a potential health hazard, but there is still unknown about its effects on spermatogenesis. Our results showed that PFHxS-treated mice have significant reproductive toxicity, including a decrease in sperm count and motility, and the levels of sex hormones (P < 0.05). Concurrently, structural abnormalities are observed in sperm, affecting ≈60-75% of those in the PFHxS-treated group. Additionally, it is found that the structure of the blood-testis barrier (BTB) is damaged after PFHxS treatment, leading to higher expression levels of inflammatory cytokines in the microenvironment for spermatogenesis. Moreover, the expression of proteins associated with mitochondrial biogenesis, including PTEN-induced kinase 1 (PINK1) and NADPH oxidase 4 (NOX4), is dysregulated in the testes after PFHxS treatment. Based on metabolome data, the differential metabolite 3-hydroxybutanoic acid is identified in the PFHxS-treated group, which can regulate the histone Kac levels, especially H3K4ac and H3K9ac. In summary, the results of this study suggest that in the testes of PFHxS-treated mice, inflammatory factors disrupt the mitochondrial function and metabolic profiles and hinder the progress of gene transcription through histone Kac, ultimately causing sperm dysfunction.

Serum lipids mediate the association of per- and polyfluoroalkyl substances exposure and age-related macular degeneration

BACKGROUND

This study aims to investigate the connection between serum lipids, per- and polyfluoroalkyl substances (PFAS), and age-related macular degeneration (AMD) risk and assess whether serum lipids mediate the association between PFAS and AMD.

METHODS

1605 participants were enrolled from NHANES 2005-2008. Four serum PFAS levels with high detective rates, including perfluorononanoic acid (PFNA), perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), and perfluorohexane sulfonic acid (PFHxS) were examined. Restricted cubic spline analysis (RCS) and weighted quantile sum (WQS) analysis were employed to detect nonlinear and mixed exposure effects.

RESULTS

PFOS level was associated with any AMD (OR, 1.54; 95% CI, 1.12 to 2.11; P = 0.011), early AMD (OR, 1.43; 95% CI, 1.06 to 1.95; P = 0.024), and late AMD (OR, 3.35; 95% CI, 1.55 to 7.23; P = 0.004) risk. PFHxS (OR, 1.72; 95% CI, 1.01 to 2.93; P = 0.045) and PFOA (OR, 2.10; 95% CI, 1.21 to 3.63; P = 0.011) levels were associated with late AMD risk. The RCS showed a nonlinear connection between PFOS exposure and AMD risk (P nonlinear = 0.006). WQS analysis indicated a positive relationship between mixed PFAS exposure and AMD risk (OR, 1.34; 95% CI, 1.03 to 1.75; P = 0.030). Serum total cholesterol (TC) and high-density lipoprotein (HDL) cholesterol were associated with AMD risk (ORTC, 1.005; 95% CI, 1.001 to 1.009; P = 0.026. ORHDL, 1.028; 95% CI, 1.014 to 1.042; P<0.001), and mediated the relationship of PFOS exposure and AMD risk, with mediation proportions of 5.73% (P = 0.020) and 7.27% (P = 0.032), respectively.

CONCLUSIONS

PFOS exposure was connected with AMD risk and serum TC and HDL mediated this relationship.

Considerations for Measurements of Aggregate PFAS Exposure in Precision Environmental Health

Per- and polyfluoroalkyl substances (PFAS) have become a major focus of research due to their widespread environmental presence and adverse health effects associated with human exposure. PFAS include legacy and emerging structures and are characterized by a range of functional groups and carbon-fluorine chains that vary in length (from fewer than 3 carbons to more than 7 carbons). Research has linked PFAS exposure to an array of health concerns, ranging from developmental and reproductive disorders to immune system impairments and an increased risk of certain cancers. In this new era of personalized health, measuring markers of PFAS exposure in human biospecimens is an important part of environmental public health surveillance. PFAS are typically measured in human blood and tissues using targeted approaches, which quantify individual PFAS structures using specific instrumentation. The diversity and complexity of PFAS, the limitations of the targeted approaches due to the sheer number of structures, and the absence of publicly available analytical standards pose significant challenges for measurement methodologies. This perspective aims to describe aggregate PFAS exposure measurements and their potential for use in precision medicine applications including a discussion of the limitations and potential benefits of these aggregate measurements. As public health organizations, healthcare professionals, and the public look for guidance regarding the safe use of and exposure to PFAS, in a pragmatic cost-effective manner, the dynamic field of measurement science is poised to respond with innovative technological solutions to an important public health need.

Association between serum per- and polyfluoroalkyl substances levels and metabolic dysfunction-associated steatotic liver disease

Experimental evidences have suggested that Per- and polyfluoroalkyl substances (PFASs) were hepatotoxicity, but epidemiologic inconsistencies. There were 1751 participants included in this study after excluding chronic hepatitis, cirrhosis, excessive alcohol drinkers, and those with missing key variables. Totally 30 PFASs were quantified using ultrahigh-pressure liquid chromatography tandem mass spectrometer (UPLC-MS). Metabolic dysfunction-associated steatotic liver disease (MASLD) defined as the presence of hepatic steatosis diagnosed on abdominal B-ultrasound in conjunction with at least one cardiometabolic risk factors (CMRF) and without other discernible cause. After multivariate adjustment, perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluoroalkyl carboxylates (ΣPFCAs), and perfluoroheptanoic acid (PFHpA) were positively associated with the risk of MASLD. Specifically, for each natural log-transformed unit increase in PFOA, PFNA, and ΣPFCAs, the risk of MASLD increased by 27% (95% confidence interval (CI): 1.09-1.48), 10% (95% CI: 0.99-1.23), and 29% (95% CI: 1.09-1.53), respectively. Compared with those in Tertile 1 of PFOA, PFNA, and ΣPFCAs, the risk of MASLD was increased by 35% (95% CI: 1.06-1.71, Ptrend = 0.019), 46% (95% CI: 1.15-1.85, Ptrend = 0.0018), and 43% (95% CI: 1.13-1.82, Ptrend = 0.0032) in Tertile 3, respectively. For PFHpA (detection rate: 14.79%), individuals with PFHpA levels above the detection limit had increased risk of MASLD by 54% (95% CI: 1.17-2.01) compared with those with PFHpA levels below the detection limit. While 8:2 chlorinated polyfluoroethersulfonic acid (8:2 Cl-PFESA) was inversely associated with steatotic liver disease (SLD) combined with 4 or 5 CMRFs (odds ratio per ln-unit = 0.87, 95% CI: 0.77-0.99). Mixed exposure analysis showed PFNA manifested a significant positive effect, while PFUdA had a significant negative effect. No association was found between other PFASs and MASLD prevalence. More prospective studies are needed to validate our conclusions.

Assessment of Cytotoxicity and Genotoxicity of Plasma-Treated Perfluorooctanesulfonate Containing Water Using In Vitro Bioassays

The contamination of ground and surface waters with per- and polyfluoroalkyl substances (PFASs) is of major concern due to their potential adverse effects on human health. The carbon-fluorine bond makes these compounds extremely stable and hardly degradable by natural processes. Therefore, methods for PFAS removal from water are desperately needed. In this context, plasma treatment of water has been proposed as an effective method with reported removal rates exceeding 90%. However, the high reactivity of plasma discharge results in the formation of many reactive species, like radicals, ozone, or even solvated electrons, which lead to a complex reaction cascade and, consequently, to the generation of a wide variety of different chemical products. The toxicological properties of these PFAS breakdown products are largely unknown. The present study focuses on a toxicological assessment of PFAS-containing plasma-treated water samples. Aqueous solutions of long-chain perfluorooctanesulfonate (PFOS) were treated with various plasma-atmospheric regimes. Subsequently, plasma-treated water samples were subjected to in vitro bioassays. Cytotoxicity and genotoxicity were assessed with the MTS assay using human liver cells (HepG2) and the Ames MPFTM assay using Salmonella Typhimurium strains. Our results demonstrate varying cyto- and genotoxic properties of water containing PFAS breakdown products depending on the atmosphere present during plasma treatment. Based on the results of this study, the atmosphere used during plasma treatment affects the toxicological properties of the treated sample. Further studies are therefore needed to uncover the toxicological implications of the different treatment parameters, including the PFAS starting compound, the atmosphere during treatment, as well as the quantity of plasma energy applied.

Effects of per- and polyfluoroalkyl substances on the liver: Human-relevant mechanisms of toxicity

Per- and polyfluoroalkyl substances (PFAS) are abundantly used in a plethora of products with applications in daily life. As a result, PFAS are widely distributed in the environment, thus providing a source of exposure to humans. The majority of human exposure to PFAS is attributed to the human diet, which encompasses drinking water. Their chemical nature grants persistent, accumulative and toxic properties, which are currently raising concerns. Over the past few years, adverse effects of PFAS on different organs have been repeatedly documented. Numerous epidemiological studies established a clear link between PFAS exposure and liver toxicity. Likewise, effects of PFAS on liver homeostasis, lipid metabolism, bile acid metabolism and hepatocarcinogenesis have been reported in various in vitro and in vivo studies. This review discusses the role of PFAS in liver toxicity with special attention paid to human relevance as well as to the mechanisms underlying the hepatotoxic effects of PFAS. Future perspectives and remaining knowledge gaps were identified to enhance future PFAS risk assessment.

Association between sleep and gallstone disease in United States adults: A cross-sectional study

BACKGROUND

Both gallstone disease and sleep disorders are important public health problems. Few studies to date have investigated the associations between sleep and gallstone disease in humans. This study aimed to assess whether sleep factors (sleep time, sleep amounts, trouble sleeping) were associated with gallstone disease in the United States adults.

METHODS

This was a population-based cross-sectional study of US adults, which included data of participants aged over 20 years from the National Health and Nutrition Examination Survey (NHANES) gathered between 2017 and March 2020. The assessment of gallstone disease and sleep factors was based on self-reported data. We used sample-weighted logistic regression and restricted cubic spline models to explore the associations between sleep factors and gallstone disease. Subgroup analyses were conducted to assess the interaction between trouble sleeping and interacting factors.

RESULTS

The prevalence of gallstone disease was 11% among the 9,210 adult participants. Going to bed late on weekdays (OR, 1.41; 95% CI, 1.15 to 1.74) and weekends (OR, 1.43; 95% CI, 1.14 to 1.78), and short sleep duration on weekdays (OR, 1.29; 95% CI, 1.00 to 1.68) were factors associated with increased risk of gallstone disease, and we detected dose-response associations with the restricted cubic spline model (RCS) models, after adjusting for confounders. Presenting trouble sleeping was associated with increased risk of gallstone disease (OR, 1.52; 95% CI, 1.03 to 2.23) and the association was influenced by the presence of thyroid disease (P for interaction = 0.037).

CONCLUSIONS

Our study results indicate that going to bed late, short sleep duration, and trouble sleeping were associated with increased risk of gallstone disease in a nationally representative sample of adults in the US.

Development, validation, and clinical assessment of a liquid chromatography-tandem mass spectrometry serum assay for per- and polyfluoroalkyl substances (PFAS) recommended by the National Academies of Science, Engineering, and Medicine (NASEM)

Per- and polyfluoroalkyl substances (PFAS) are widely used in industry, residential, and consumer products. Studies have shown associations between high PFAS exposure and adverse health effects. In 2022, the National Academies of Science, Engineering, and Medicine (NASEM) published Guidance on PFAS Exposure, Testing, and Clinical Follow-up providing laboratory and clinical direction. The Guidance suggests nine PFAS should be measured in serum or plasma specimens and summed to provide a total PFAS concentration using a NASEM-recommended method. Follow-up clinical recommendations are based on the calculated PFAS NASEM summation. We developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method in accordance with NASEM recommendations but distinguished by the ability to separate closely related structural isomers. As part of our validation, PFAS prevalence was evaluated in a population survey comprised of clinical donor and remnant specimens (n = 1023 in total). In this study, 82.2% of the specimens had PFAS NASEM summations of 2 to < 20 ng/mL and 2.5% had a summation ≥ 20 ng/mL. The median PFAS NASEM summation was 4.65 ng/mL in this study, lower than the 7.74 ng/mL median observed in the 2017-2020 Centers for Disease Control and Prevention, National Health and Nutrition Examination Survey (n = 3072). This lower median PFAS NASEM summation may reflect a decline in PFAS population levels over time or sample population exposure differences.

In vitro screening of understudied PFAS with a focus on lipid metabolism disruption

Per- and polyfluoroalkyl substances (PFAS) are man-made chemicals used in many industrial applications. Exposure to PFAS is associated with several health risks, including a decrease in infant birth weight, hepatoxicity, disruption of lipid metabolism, and decreased immune response. We used the in vitro cell models to screen six less studied PFAS [perfluorooctane sulfonamide (PFOSA), perfluoropentanoic acid (PFPeA), perfluoropropionic acid (PFPrA), 6:2 fluorotelomer alcohol (6:2 FTOH), 6:2 fluorotelomer sulfonic acid (6:2 FTSA), and 8:2 fluorotelomer sulfonic acid (8:2 FTSA)] for their capacity to activate nuclear receptors and to cause differential expression of genes involved in lipid metabolism. Cytotoxicity assays were run in parallel to exclude that observed differential gene expression was due to cytotoxicity. Based on the cytotoxicity assays and gene expression studies, PFOSA was shown to be more potent than other tested PFAS. PFOSA decreased the gene expression of crucial genes involved in bile acid synthesis and detoxification, cholesterol synthesis, bile acid and cholesterol transport, and lipid metabolism regulation. Except for 6:2 FTOH and 8:2 FTSA, all tested PFAS downregulated PPARA gene expression. The reporter gene assay also showed that 8:2 FTSA transactivated the farnesoid X receptor (FXR). Based on this study, PFOSA, 6:2 FTSA, and 8:2 FTSA were prioritized for further studies to confirm and understand their possible effects on hepatic lipid metabolism.

Perfluoroalkyl substances and immunotoxicity: An in vitro structure-activity relationship study in THP-1-derived monocytes and macrophages

Recently, PFASs toxicity for the human immune system has become a growing concern. However, there is currently limited information on PFASs immunotoxicity beyond PFHxS, PFOA, PFOS, and PFNA. Therefore, it is urgent to close the present knowledge gap by testing a wider range of compounds. In the present study, twelve compounds were tested for a relationship between the chain-length and headgroup of a PFAS and its cytotoxic for THP-1. As such, THP-1, either as monocytes or differentiated macrophages, were exposed to PFASs in a concentration range of 0-800 μM for either 3 or 24 h. After that, cell viability and reactive oxygen species (ROS) generation were assessed using MTT and DCFH assay, respectively. PFASs' cytotoxicity is dependent on both their chain-length and headgroups. Cell viability decreased with increasing chain-length, and FTOHs displayed markedly higher toxicity than PFCAs and PFSAs. PFASs were ranked based on their calculated Relative Potency Factor. The ranking for the cytotoxicity data on monocytes appears to be 6:2 FTOH ≫ PFNA > PFDA > PFOS > PFOA >4: 2 FTOH > PFHxS = PFHxA > PFBA. For macrophages, this ranking was as follows: 6:2 FTOH >4:2 FTOH > PFOS > PFDA > PFNA > PFOA > PFHxS. The results observed for the ROS generating potential differed as FTOHs generated no ROS. Here, the ranking in monocytes was PFOA > PFNA > PFOS > PFHxS > PFDA > PFHxA = PFBS = PFBA. The ranking for macrophages was PFNA > PFDA ≥ PFOA > PFOS > PFHxA > PFHxS > PFBA = PFBS. In conclusion, the carbon chain-length and functional headgroup of a PFAS are major determinants for their toxicity to THP-1 cells. Furthermore, our study demonstrates the most potent cytotoxic effect for FTOHs in vitro, which has not been observed before to the authors' knowledge.

Risk assessment for perfluorooctanoic acid (PFOA) in air, blood serum and water: mortality from liver and kidney disease

BACKGROUND

Cancer and non-cancer associations have been observed with PFAS (perfluoroalkyl and polyfluoroalkyl) substances in the general population, in populations from locally contaminated environments and in exposed workers.

METHODS

A quantitative risk assessment on the PFAS substance perfluorooctanoic acid (PFOA) was conducted for six outcomes using two occupational mortality studies that reported sufficient data to estimate exposure-relationships in relation to serum PFOA levels. Excess lifetime mortality risks were calculated using a life table procedure that applies an exposure response to time-dependent PFOA serum levels for a surviving hypothetical population from ages 20 to 85. Both occupational and general population exposures were described as serum levels, and as air and drinking water concentrations.

RESULTS

The estimated occupational inhalation concentrations conferring the benchmark one-per-thousand lifetime risk were 0.21 µg/m3 for chronic kidney disease, 1.0 µg/m3 for kidney cancer and (from the two studies) 0.67 and 1.97 µg/m3 for chronic liver disease. Specific excess lifetime risks estimated in the general population at current PFOA serum levels (~ 1 ng/mL) range 1.5-32 per 100 000 which corresponds to drinking water concentrations of less than 10 ppt.

CONCLUSION

Over eight outcome risk estimates, the serum PFOA concentrations conferring 1/1000 occupational lifetime risk ranged 44 to 416 ng/mL corresponding to air concentrations ranging 0.21 to 1.99 µg/m3. The analyses provide a preliminary PFOA quantitative risk assessment for liver and kidney disease mortality which, together with reported assessments for several other end-points, would inform policy on PFAS.

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

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

Exposure to PFAS chemicals induces sex-dependent alterations in key rate-limiting steps of lipid metabolism in liver steatosis

Toxicants with the potential to bioaccumulate in humans and animals have long been a cause for concern, particularly due to their association with multiple diseases and organ injuries. Per- and polyfluoro alkyl substances (PFAS) and polycyclic aromatic hydrocarbons (PAH) are two such classes of chemicals that bioaccumulate and have been associated with steatosis in the liver. Although PFAS and PAH are classified as chemicals of concern, their molecular mechanisms of toxicity remain to be explored in detail. In this study, we aimed to identify potential mechanisms by which an acute exposure to PFAS and PAH chemicals can induce lipid accumulation and whether the responses depend on chemical class, dose, and sex. To this end, we analyzed mechanisms beginning with the binding of the chemical to a molecular initiating event (MIE) and the consequent transcriptomic alterations. We collated potential MIEs using predictions from our previously developed ToxProfiler tool and from published steatosis adverse outcome pathways. Most of the MIEs are transcription factors, and we collected their target genes by mining the TRRUST database. To analyze the effects of PFAS and PAH on the steatosis mechanisms, we performed a computational MIE-target gene analysis on high-throughput transcriptomic measurements of liver tissue from male and female rats exposed to either a PFAS or PAH. The results showed peroxisome proliferator-activated receptor (PPAR)-α targets to be the most dysregulated, with most of the genes being upregulated. Furthermore, PFAS exposure disrupted several lipid metabolism genes, including upregulation of fatty acid oxidation genes (Acadm, Acox1, Cpt2, Cyp4a1-3) and downregulation of lipid transport genes (Apoa1, Apoa5, Pltp). We also identified multiple genes with sex-specific behavior. Notably, the rate-limiting genes of gluconeogenesis (Pck1) and bile acid synthesis (Cyp7a1) were specifically downregulated in male rats compared to female rats, while the rate-limiting gene of lipid synthesis (Scd) showed a PFAS-specific upregulation. The results suggest that the PPAR signaling pathway plays a major role in PFAS-induced lipid accumulation in rats. Together, these results show that PFAS exposure induces a sex-specific multi-factorial mechanism involving rate-limiting genes of gluconeogenesis and bile acid synthesis that could lead to activation of an adverse outcome pathway for steatosis.

How Per- and Poly-Fluoroalkyl Substances Affect Gamete Viability and Fertilization Capability: Insights from the Literature

There has been emerging research linking per- and poly-fluoroalkyl substances (PFAS) to gamete viability and fertility. PFAS, prevalent in the environment and water supplies, undergo slow degradation due to their C-F bond and a long half-life (2.3-8.5 years). In females, PFAS inhibit the hypothalamic-pituitary-gonadal (HPG) axis, reducing follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels, leading to the inhibition of androgen and estradiol production. PFAS have been found to cause detrimental effects on egg quality through impairing folliculogenesis. In males, PFAS can impair sperm motility and morphology: two fundamental qualities of successful fertilization. PFAS exposure has been proven to inhibit testosterone production, sperm capacitation, and acrosomal reaction. After fertilization, the results of PFAS exposure to embryos have also been investigated, showing reduced development to the blastocyst stage. The aim of this review is to report the main findings in the literature on the impact of PFAS exposure to gamete competency and fertilization capability by highlighting key studies on both male and female fertility. We report that there is significant evidence demonstrating the negative impacts on fertility after PFAS exposure. At high doses, these environmentally abundant and widespread compounds can significantly affect human fertility.

Cross-Sectional Associations between Prenatal Per- and Poly-Fluoroalkyl Substances and Bioactive Lipids in Three Environmental Influences on Child Health Outcomes (ECHO) Cohorts

Prenatal per- and poly-fluoroalkyl substances (PFAS) exposure may influence gestational outcomes through bioactive lipids─metabolic and inflammation pathway indicators. We estimated associations between prenatal PFAS exposure and bioactive lipids, measuring 12 serum PFAS and 50 plasma bioactive lipids in 414 pregnant women (median 17.4 weeks' gestation) from three Environmental influences on Child Health Outcomes Program cohorts. Pairwise association estimates across cohorts were obtained through linear mixed models and meta-analysis, adjusting the former for false discovery rates. Associations between the PFAS mixture and bioactive lipids were estimated using quantile g-computation. Pairwise analyses revealed bioactive lipid levels associated with PFDeA, PFNA, PFOA, and PFUdA (p < 0.05) across three enzymatic pathways (cyclooxygenase, cytochrome p450, lipoxygenase) in at least one combined cohort analysis, and PFOA and PFUdA (q < 0.2) in one linear mixed model. The strongest signature revealed doubling in PFOA corresponding with PGD2 (cyclooxygenase pathway; +24.3%, 95% CI: 7.3-43.9%) in the combined cohort. Mixture analysis revealed nine positive associations across all pathways with the PFAS mixture, the strongest signature indicating a quartile increase in the PFAS mixture associated with PGD2 (+34%, 95% CI: 8-66%), primarily driven by PFOS. Bioactive lipids emerged as prenatal PFAS exposure biomarkers, deepening insights into PFAS' influence on pregnancy outcomes.

HNF4A as a potential target of PFOA and PFOS leading to hepatic steatosis: Integrated molecular docking, molecular dynamic and transcriptomic analyses

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are indeed among the most well known and extensively studied Per- and polyfluoroalkyl substances (PFASs), and increasing evidence confirm their effects on human health, especially liver steatosis. Nonetheless, the molecular mechanisms of their initiation of hepatic steatosis is still elusive. Therefore, potential targets of PFOA/PFOS must be explored to ameliorate its adverse consequences. This research aims to investigate the molecular mechanisms of PFOA and PFOS-induced liver steatosis, with emphasis on identifying a potential target that links these PFASs to liver steatosis. The potential target that causes PFOA and PFOS-induced liver steatosis have been explored and determined based on molecular docking, molecular dynamics (MD) simulation, and transcriptomics analysis. In silico results show that PFOA/PFOS can form a stable binding conformation with HNF4A, and PFOA/PFOS may interact with HNF4A to affect the downstream conduction mechanism. Transcriptome data from PFOA/PFOS-induced human stem cell spheres showed that HNF4A was inhibited, suggesting that PFOA/PFOS may constrain its function. PFOS mainly down-regulated genes related to cholesterol synthesis while PFOA mainly up-regulated genes related to fatty acid β-oxidation. This study explored the toxicological mechanism of liver steatosis caused by PFOA/PFOS. These compounds might inhibit and down-regulate HNF4A, which is the molecular initiation events (MIE) that induces liver steatosis.

PFHxS Exposure and the Risk of Non-Alcoholic Fatty Liver Disease

Perfluorohexanesulfonic acid (PFHxS) is a highly prevalent environmental pollutant, often considered to be less toxic than other poly- and perfluoroalkyl substances (PFASs). Despite its relatively lower environmental impact compared to other PFASs, several studies have suggested that exposure to PFHxS may be associated with disruptions of liver function in humans. Nevertheless, the precise pathomechanisms underlying PFHxS-induced non-alcoholic fatty liver disease (NAFLD) remain relatively unclear. Therefore, this study applied our previously published transcriptome dataset to explore the effects of PFHxS exposure on the susceptibility to NAFLD and to identify potential mechanisms responsible for PFHxS-induced NAFLD through transcriptomic analysis conducted on zebrafish embryos. Results showed that exposure to PFHxS markedly aggravated hepatic symptoms resembling NAFLD and other metabolic syndromes (MetS) in fish. Transcriptomic analysis unveiled 17 genes consistently observed in both NAFLD and insulin resistance (IR), along with an additional 28 genes identified in both the adipocytokine signaling pathway and IR. These shared genes were also found within the NAFLD dataset, suggesting that hepatic IR may play a prominent role in the development of PFHxS-induced NAFLD. In conclusion, our study suggests that environmental exposure to PFHxS could be a potential risk factor for the development of NAFLD, challenging the earlier notion of PFHxS being safer as previously claimed.

The Association of Perfluoroalkyl Substance Exposure and a Serum Liver Function Marker in Korean Adults

Perfluoroalkyl substances (PFAS), widely used throughout industry and daily life, are currently one of the environmental pollutants garnering the most attention worldwide. Recently, environmental pollutants have had a high profile as one of the main causes of chronic liver disease, such as non-alcoholic fatty liver disease. Research on PFAS is actively underway. Although Korea has a remarkably high prevalence of chronic liver disease, and it continues to increase, only a few studies have revealed the relationship between PFAS and liver disease. In addition, regulations on PFAS in Korea are delayed compared to developed countries, such as Europe and the United States, and public interest is insufficient compared to others. Therefore, we would like to investigate the exposure of Koreans to PFAS in the blood and examine the relationship between these substances and markers of liver function (AST, ALT, and GGT). This study was based on the results of the Korean National Environmental Health Survey (KoNEHS) 2018–2020 (Cycle 4), and a total of 2961 subjects were selected. The concentration of PFAS in the blood of Korean adults was measured to be significantly higher based on the geometric mean compared to the results of recently investigated American adults based on the National Health and Nutrition Examination Survey (NHANES, 2017-2018). A multivariable linear regression analysis adjusted for age, sex, body mass index (BMI), smoking status, alcohol intake, and regular exercise was performed to examine changes in three liver function markers as the serum PFAS concentration increased. We found that some of the five PFAS (PFOA, PFOS, PFHxS, PFNA, and PFDeA) were significantly associated with increased liver enzymes. It is necessary to recognize the threat of PFAS to the human body and to discuss regulations and alternatives in earnest. Continuous follow-up studies are required through a well-designed cohort.

Association of per- and polyfluoroalkyl substance exposure with metabolic syndrome and its components in adults and adolescents

Per- and polyfluoroalkyl substances (PFAS) are widespread contaminants, but few studies have explored the relationship between PFAS and levels of metabolic syndrome (MetS) in the population. The available evidence of an association is also conflicting. We selected adults and adolescents with complete PFAS data from the National Health and Nutrition Examination Survey conducted between 2003 and 2018. We analyzed the association between PFAS and MetS using multivariate logistic regression models and evaluated potential nonlinear relationships with restricted cubic spline models. Additionally, we employed weighted quantile sum (WQS) regressions to uncover the multiple exposure effects and relative weights of each PFAS. Finally, we conducted a series of sensitivity analyses to test the robustness of our findings. In this population-based study, we analyzed data from a total of 4,973 adults, aged 20-85 years, and 1,381 adolescents, aged 12-19 years. Using fully adjusted multivariate logistic regression models, we found that serum levels of perfluorodecanoate (PFDA) [0.65 (0.50, 0.85)] and total PFAS [0.92 (0.85, 0.99)] were negatively associated with the prevalence of MetS in adults. Similarly, in adolescents, we observed negative correlations between the prevalence of MetS and levels of PFDA [0.55 (0.38, 0.80)], perfluorooctanoic acid (PFOA) [0.62 (0.39, 1.00)], perfluorooctane sulfonic acid (PFOS) [0.59 (0.36, 0.96)], and total PFAS [0.61 (0.37, 0.99)]. Additionally, our study identified statistically significant negative associations between serum levels of PFAS and certain components of MetS, primarily elevated fasting glucose and lower high-density lipoprotein cholesterol. Our study found that PFAS was associated with a lower prevalence of MetS in both adults and adolescents, offering new insights into the relationship between PFAS and metabolic health. Interestingly, however, we observed conflicting findings across the components of MetS. Specifically, we observed that PFAS had a negative correlation with some metrics and a positive correlation with others. These conflicting results point to a complex interplay between PFAS and various metrics of metabolic health.

Enhanced coagulation coupled with cyclic IX adsorption-ARP regeneration for removal of PFOA in drinking water treatment

Laboratory investigations were conducted to demonstrate a potentially transformative, cost-efficient per- and polyfluoroalkyl substances (PFAS) treatment approach, consisting of enhanced coagulation and repeated ion exchange (IX)-advanced reduction process (ARP) for concurrent PFAS removal and IX resin regeneration. Enhanced alum coagulation at the optimal conditions (pH 6.0, 60 mg/L alum) could preferentially remove high molecular-weight, hydrophobic natural organic matter (NOM) from 5.0- to ~1.2-mg/L DOC in simulated natural water. This facilitated subsequent IX adsorption of perfluorooctanoic acid (PFOA, a model PFAS in this study) (20 μg/L) using IRA67 resin by minimizing the competition of NOM for functional sites on the resin. The PFOA/NOM-laden resin was then treated by ARP, generating hydrated electrons (eaq - ) that effectively degraded PFOA. The combined IX-ARP regeneration process was applied over six cycles to treat PFOA in pre-coagulated simulated natural water, nearly doubling the PFOA removal compared with the control group without ARP regeneration. This study underscores the potential of enhanced coagulation coupled with cyclic IX-ARP regeneration as a promising, cost-effective solution for addressing PFOA pollution in water. PRACTITIONER POINTS: Enhanced alum coagulation can substantially mitigate NOM to favor the following IX removal of PFOA in water. Cyclic IX adsorption-ARP regeneration offers an effective, potentially economical solution to the PFOA pollution in water. ARP can effectively degrade PFOA during the ARP regeneration of PFOA/NOM-laden resin.

Pets, Genuine Tools of Environmental Pollutant Detection

In a shared environment, our companion animals became unintended sentinels for pollutant exposure consequences, developing even earlier similar conditions to humans. This review focused on the human-pet cohabitation in an environment we all share. Alongside other species, canine and feline companions are veritable models in human medical research. The latency period for showing chronic exposure effects to pollutants is just a few years in them, compared to considerably more, decades in humans. Comparing the serum values of people and their companion animals can, for example, indicate the degree of poisonous lead load we are exposed to and of other substances as well. We can find 2.4 times higher perfluorochemicals from stain- and grease-proof coatings in canine companions, 23 times higher values of flame retardants in cats, and 5 times more mercury compared to the average levels tested in humans. All these represent early warning signals. Taking these into account, together with the animal welfare orientation of today's society, finding non-invasive methods to detect the degree of environmental pollution in our animals becomes paramount, alongside the need to raise awareness of the risks carried by certain chemicals we knowingly use.

Sex, Nutrition, and NAFLD: Relevance of Environmental Pollution

Non-alcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease and represents an increasing public health issue given the limited treatment options and its association with several other metabolic and inflammatory disorders. The epidemic, still growing prevalence of NAFLD worldwide cannot be merely explained by changes in diet and lifestyle that occurred in the last few decades, nor from their association with genetic and epigenetic risk factors. It is conceivable that environmental pollutants, which act as endocrine and metabolic disruptors, may contribute to the spreading of this pathology due to their ability to enter the food chain and be ingested through contaminated food and water. Given the strict interplay between nutrients and the regulation of hepatic metabolism and reproductive functions in females, pollutant-induced metabolic dysfunctions may be of particular relevance for the female liver, dampening sex differences in NAFLD prevalence. Dietary intake of environmental pollutants can be particularly detrimental during gestation, when endocrine-disrupting chemicals may interfere with the programming of liver metabolism, accounting for the developmental origin of NAFLD in offspring. This review summarizes cause-effect evidence between environmental pollutants and increased incidence of NAFLD and emphasizes the need for further studies in this field.

Perfluorooctanoic Acid (PFOA) Exposure and Abnormal Alanine Aminotransferase: Using Clinical Consensus Cutoffs Compared to Statistical Cutoffs for Abnormal Values

BACKGROUND

Per- and polyfluoroalkyl substances (PFASs) including perfluorooctanoic acid (PFOA) are ubiquitous environmental contaminants. Prior analysis in the large "C8 Health Project" population defined abnormal alanine aminotransferase (ALT) with statistically derived cutoffs (>45 IU/L in men, >34 IU/L in women).

OBJECTIVE

To explore the degree to which PFOA was associated with modern, clinically predictive ALT biomarker cutoffs in obese and nonobese participants, excluding those with diagnosed liver disease.

METHODS

We reevaluated the relationship of serum PFOA to abnormal ALT using predictive cutoff recommendations including those of the American College of Gastroenterology (ACG). Evaluations modeled lifetime cumulative exposure and measured internal PFOA exposure.

RESULTS

ACG cutoff values (≥34 IU/L for males, ≥25 IU/L for females) classified 30% of males (3815/12,672) and 21% of females (3359/15,788) above ALT cutoff values. Odds ratios (OR) for above cutoff values were consistently associated with modeled cumulative and measured serum PFOA. Linear trends were highly significant. ORs by quintile showed near monotonic increases. Trends were stronger for the overweight and obese. However, all weight classes were affected.

CONCLUSION

Predictive cutoffs increase the OR for abnormal ALT results. Obesity increases ORs, yet association with abnormal ALT pertains to all weight classes. The results are discussed in context of current knowledge about the health implications of PFOA hepatotoxicity.