Exposure to novel and legacy per- and polyfluoroalkyl substances (PFASs) and associations with type 2 diabetes: A case-control study in East China

Association of co-exposure to organophosphate esters and per- and polyfluoroalkyl substances and mixture with cardiovascular-kidney-liver-metabolic biomarkers among Chinese adults

BACKGROUND

Organophosphate esters (OPEs) and Per- and polyfluoroalkyl substances (PFAS) are ubiquitous environmental contaminants with common exposure sources, leading to their widespread presence in human body. However, evidence on co-exposure to OPEs and PFAS and its impact on cardiovascular-kidney-liver-metabolic biomarkers remains limited.

METHODS

In this cross-sectional study, 467 adults were enrolled from January to May 2022 during physical visits in Shijiazhuang, Hebei province. Eleven types of OPEs and twelves types of PFAS were detected, among which eight OPEs and six PFAS contaminants were detected in more than 60% of plasma samples. Seventeen biomarkers were assessed to comprehensively evaluate the cardiovascular-kidney-liver-metabolic function. Multiple linear regression, multipollutant models with sparse partial least squares, and Bayesian kernel machine regression (BKMR) models were applied to examine the associations of individual OPEs and PFAS and their mixtures with organ function and metabolism, respectively.

RESULTS

Of the over 400 exposure-outcome associations tested when modelling, we observed robust results across three models that perfluorohexanoic acid (PFHxS) was significantly positively associated with alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), and indirect bilirubin (IBIL). Perfluorononanoic acid was significantly associated with decreased AST/ALT and increased very-low-density lipoprotein cholesterol levels. Besides, perfluorodecanoic acid was correlated with increased high lipoprotein cholesterol and perfluoroundecanoic acid was consistently associated with lower glucose level. BKMR analysis showed that OPEs and PFAS mixtures were positively associated with IBIL and TBIL, among which PFHxS was the main toxic chemicals.

CONCLUSIONS

Our findings suggest that exposure to OPEs and PFAS, especially PFHxS and PFNA, may disrupt organ function and metabolism in the general population, providing insight into the potential pathophysiological mechanisms of OPEs and PFAS co-exposure and chronic diseases.

Associations between serum perfluoroalkyl and polyfluoroalkyl concentrations and diabetes mellitus in the Korean general population: Insights from the Korean National Environmental Health Survey 2018-2020

AIMS

Recent epidemiologic research has examined the relationship between perfluoroalkyl and polyfluoroalkyl substances (PFAS) and diabetes mellitus with inconclusive findings. In this cross-sectional study, we aimed to explore the association between serum PFAS concentrations and the prevalence of prediabetes and pre-diagnostic diabetes in the general Korean population as well as the combined effects of exposure to mixed PFAS compounds.

METHODS

We analyzed data from participants aged ≥19 years enrolled in the Korean National Environmental Health Survey Cycle 4 (2018-2020). Individuals diagnosed with diabetes were excluded to minimize potential bias. We identified cases of pre-diagnostic diabetes based on the HbA1c level ≥6.5% and prediabetes as HbA1c levels of 5.7-6.49%. Serum concentrations of PFAS, including perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDeA), perfluorohexane sulfonic acid (PFHxS), and perfluorooctane sulfonic acid (PFOS), were quantified using high-performance liquid chromatography-tandem mass spectrometry. Survey-weighted logistic regression models were used to assess the relationships between PFAS levels and diabetes risk, adjusting for covariates. Additionally, Bayesian kernel machine regression (BKMR) was used to investigate the combined effects of exposure to mixed PFAS compounds.

RESULTS

In the study population excluding participants with diagnosed diabetes (n = 2709), the prevalence of pre-diagnostic diabetes and prediabetes was 4.8% and 30.1%, respectively. Significant positive associations were found between serum PFHxS and PFOS quartiles and pre-diagnostic diabetes risk. Likewise, among those without diagnosed or pre-diagnostic diabetes (n = 2579), the highest quartiles of PFDeA, PFHxS, and PFOS and the overall PFAS level were associated with an increased risk of prediabetes compared with the lowest quartiles. BKMR analysis revealed a significant positive association between overall serum PFAS level and prediabetes risk, which was most marked for PFOS.

CONCLUSIONS

These findings highlight the potential health implications of PFAS exposure and prediabetes risk. Further research is needed to validate these associations and identify potential mechanistic pathways.

Associations between serum per- and polyfluoroalkyl substances as mixtures and lipid levels: A cross-sectional study in Jinan

Per- and polyfluoroalkyl substances (PFASs) are known to be linked with dyslipidemia. Between March and June 2022, we collected 575 fasting serum samples from individuals without occupational exposure in Jinan, China. Eighteen PFASs were analyzed using UHPLC-Orbitrap MS. Multiple linear regression (MLR), Bayesian kernel machine regression (BKMR), and Quantile g-computation (QGC) models were utilized to assess the effects of both individual PFAS and PFAS mixtures on serum lipid levels, including triglycerides (TG), cholesterol (CHO), high-density lipoprotein (HDL), and low-density lipoprotein (LDL). The PFAS mixture, composed of perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorododecanoic acid (PFDoDA), perfluorotridecanoic acid (PFTrDA), perfluorohexane sulfonate (PFHxS), perfluoroheptane sulfonic acid (PFHpS), perfluorooctane sulfonate (PFOS), and 6:2 chlorinated polyfluoroalkyl ether sulfonate (6:2 Cl-PFESA), showed a positive association with CHO and LDL levels, while no distinct trend was noted in HDL and TG levels about changes in PFAS mixtures levels in BKMR and QGC models, adjusted for gender, age, BMI, occupation, and educational level. The effects of individual PFASs on lipid levels were in general consistent across MLR, BKMR and QGC models. PFUnDA and PFTrDA demonstrated greater impacts on blood lipid levels compared to other PFAS, albeit with varied directional effects. Age-stratified analysis revealed PFAS mixture effect was more pronounced in participants aged higher than 40. No obvious trend in lipid levels with changes in PFAS mixture levels in participants with age ranged from 18 to 40, while positive association between PFAS mixture and CHO and LDL was detected in participants aged higher than 40.

Perfluoroalkyl/Polyfluoroalkyl Substances: Links to Cardiovascular Disease Risk

Conservative estimates by the World Health Organization suggest that at least a quarter of global cardiovascular diseases are attributable to environmental exposures. Associations between air pollution and cardiovascular risk have garnered the most headlines and are strong, but less attention has been paid to other omnipresent toxicants in our ecosystem. Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are man-made chemicals that are extensively used in industrial and consumer products worldwide and in aqueous film-forming foam utilized in firefighting. As such, our exposure to PFAS is essentially ubiquitous. Given the long half-lives of these degradation-resistant chemicals, virtually, all people are carrying a body burden of PFAS. Health concerns related to PFAS are growing such that the National Academies of Sciences, Engineering and Medicine has recommended standards for clinical follow-up of individuals with high PFAS blood levels, including prioritizing screening for dyslipidemia. The link between PFAS and dyslipidemia has been extensively investigated, and evidence for associations is compelling. However, dyslipidemia is not the only cardiovascular risk factor with which PFAS is associated. Here, we review the epidemiological evidence for links between PFAS of concern identified by the National Academies of Sciences, Engineering and Medicine and risk factors for cardiovascular disease, including overweight/obesity, glucose intolerance, hypertension, dyslipidemia, and hyperuricemia. Moreover, we review the potential connections of PFAS with vascular disease and atherosclerosis. While observational data support associations between the National Academies of Sciences, Engineering and Medicine PFAS and selected cardiac risk factors, additional research is needed to establish causation and better understand how exposure to PFAS leads to the development of these conditions.

Dietary intake of Perfluorooctanesulfonic acid (PFOS) and glucose homeostasis parameters in a non-diabetic senior population

BACKGROUND

Endocrine disruptors (EDs) have emerged as potential contributors to the development of type-2 diabetes. Perfluorooctane sulfonate (PFOS), is one of these EDs linked with chronic diseases and gathered attention due to its widespread in food.

OBJECTIVE

To assess at baseline and after 1-year of follow-up associations between estimated dietary intake (DI) of PFOS, and glucose homeostasis parameters and body-mass-index (BMI) in a senior population of 4600 non-diabetic participants from the PREDIMED-plus study.

METHODS

Multivariable linear regression models were conducted to assess associations between baseline PFOS-DI at lower bound (LB) and upper bound (UB) established by the EFSA, glucose homeostasis parameters and BMI.

RESULTS

Compared to those in the lowest tertile, participants in the highest tertile of baseline PFOS-DI in LB and UB showed higher levels of HbA1c [β-coefficient(CI)] [0.01 %(0.002 to 0.026), and [0.06 mg/dL(0.026 to 0.087), both p-trend ≤ 0.001], and fasting plasma glucose in the LB PFOS-DI [1.05 mg/dL(0.050 to 2.046),p-trend = 0.022]. Prospectively, a positive association between LB of PFOS-DI and BMI [0.06 kg/m2(0.014 to 0.106) per 1-SD increment of energy-adjusted PFOS-DI was shown. Participants in the top tertile showed an increase in HOMA-IR [0.06(0.016 to 0.097), p-trend = 0.005] compared to participants in the reference tertile after 1-year of follow-up.

DISCUSSION

This is the first study to explore the association between DI of PFOS and glucose homeostasis. In this study, a high baseline DI of PFOS was associated with a higher levels of fasting plasma glucose and HbA1c and with an increase in HOMA-IR and BMI after 1-year of follow-up.

Short-chain chlorinated paraffin (SCCP) exposure and type 2 diabetes risk: A population-based case-control study in East China

Exposure to persistent organic pollutants may be associated to type 2 diabetes, but the studies on associations between short-chain chlorinated paraffin (SCCP) exposure and type 2 diabetes risk in humans are still scarce. Here, we conducted a case-control study involving 344 participants in Shandong Province, East China, to explore the effects of SCCPs on type 2 diabetes risk and their correlations with glycemic biomarker and serum lipid parameters. SCCPs were detected in all serum samples with a median concentration of 24 ng mL-1 in cases and 19 ng mL-1 in controls. Exposure to C10-CPs, C11-CPs, and ΣSCCPs were positively associated with the risk of type 2 diabetes after adjusting for confounders. The associations remained consistent in stratified analyses but stronger in male participants and obese individuals. In the control group, there were significant and positive correlations between SCCP exposure and levels of total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), total lipid, and non-high-density lipoprotein-cholesterol. Significant joint effects on SCCP exposure and lipid parameters were observed in females when analyzed by the quantile-based g-computation model, and C10-CPs showed the highest contribution. Mediation analysis showed that LDL-C had significant mediation effects on the associations between C10-CPs, C11-CPs, and ΣSCCPs exposure and risk of type 2 diabetes. Moreover, TC and high-density lipoprotein-cholesterol were mediators in the relationship between C11-CPs and type 2 diabetes. Taken together, our study revealed that human exposure to SCCPs may increase the risk of type 2 diabetes and disrupt lipid metabolism.

The Association of Hypertension with Perfluoroalkyl and Polyfluoroalkyl Substances

Perfluoroalkyl and polyfluoroalkyl substance (PFAS) is a large group of fluorinated synthetic chemicals, e.g., perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorohexanesulfonic acid (PFHxS), perfluorodecanoic acid (PFDA), and perfluorononanoic acid (PFNA). Many epidemiological studies have found that PFAS exposure is associated with hypertension risk, but others possess a different opinion. Overall, the relationship between PFASs and hypertension risk remains controversial. We sought to conduct a systematic review and meta-analysis to clarify the association between PFAS exposure and human risk of hypertension.We conducted a meta-analysis based on population-involving studies published from 1975 to 2023, which we collected from Web of Science, PubMed, and Embase databases. The odds ratio (OR) and standardized mean difference (SMD), with their 95% confidence interval (CI), were used to assess the risk of hypertension with PFAS exposure. The statistical heterogeneity among studies was assessed with the Q-test and I2 statistics. Research publications related to our meta-analysis topic were systematically reviewed.Fourteen studies involving 71,663 participants, in which 26,281 suffered hypertension, met the inclusion criteria. Our analyses suggest that exposure to general PFAS (OR = 1.09, 95% CI = 1.04-1.14) or PFOS (OR = 1.17, 95% CI = 1.05-1.30) is associated with hypertension risk. Specifically, elevated levels of general PFAS (SMD = 0.25, 95% CI = 0.08-0.42), PFHxS (SMD = 0.17, 95% CI = 0.07-0.27), and PFDA (SMD = 0.08, 95% CI = 0.02-0.13) are associated with a high risk of hypertension.Our meta-analysis indicates that PFAS exposure is a risk factor for hypertension, and increased hypertension risk is associated with higher PFAS levels. Further study may eventually provide a better and more comprehensive elucidation of the potential mechanism of this association.

Cardiometabolic health and per and polyfluoroalkyl substances in an Inuit population

INTRODUCTION

The cardiometabolic health status of Inuit in Nunavik has worsened in the last thirty years. The high concentrations of perfluoroalkyl acids (PFAAs) may be contributing to this since PFAAs have been linked with hypercholesterolemia, diabetes, and high blood pressure. The aim of this study was to examine the association between a PFAAs mixture and lipid profiles, Type II diabetes, prediabetes, and high blood pressure in this Inuit population.

METHODS

We included 1212 participants of the Qanuilirpitaa? 2017 survey aged 16-80 years. Two mixture models (quantile g-computation and Bayesian Kernel Machine Regression (BKMR)) were used to investigate the associations between six PFAAs (PFHxS, PFOS, PFOA and three long-chain PFAAs (PFNA, PFDA and PFUnDA)) with five lipid profiles and three cardiometabolic outcomes. Non-linearity and interaction between PFAAs were further assessed.

RESULTS

An IQR increase in all PFAAs congeners resulted in an increase in total cholesterol (β 0.15, 95% confidence interval (CI) 0.06, 0.24), low-density lipoprotein cholesterol (LDL) (β 0.08, 95% CI 0.01, 0.16), high-density lipoprotein cholesterol (HDL) (β 0.04, 95% CI 0.002, 0.08), apolipoprotein B-100 (β 0.03, 95% CI 0.004, 0.05), and prediabetes (OR 1.80, 95% CI 1.11, 2.91). There was no association between PFAAs and triglycerides, diabetes, or high blood pressure. Long-chain PFAAs congeners were the main contributors driving the associations. Associations were largely linear, and there was no evidence of interaction between the PFAAs congeners.

CONCLUSIONS

Our study provides further evidence of increasing circulating lipids with increased exposure to PFAAs. The increased risk of prediabetes points to the influence of PFAAs on potential clinical outcomes. International regulation of PFAAs is essential to curb PFAAs exposure and related health effects in Arctic communities.

Priority list of potential endocrine-disrupting chemicals in food chemical contaminants: a docking study and in vitro/epidemiological evidence integration

Diet is an important exposure route of endocrine-disrupting chemicals (EDCs), but many unfiltered potential EDCs remain in food. The in silico prediction of EDCs is a popular method for preliminary screening. Potential EDCs in food were screened using Endocrine Disruptome, an open-source platform for inverse docking, to predict the binding probabilities of 587 food chemical contaminants with 18 human nuclear hormone receptor (NHR) conformations. In total, 25 contaminants were bound to multiple NHRs such as oestrogen receptor α/β and androgen receptor. These 25 compounds mainly include pesticides and per- and polyfluoroalkyl substances (PFASs). The prediction results were validated with the in vitro data. The structural features and the crucial amino acid residues of the four NHRs were also validated based on previous literature. The findings indicate that the screening has good prediction efficiency. In addition, the epidemic evidence about endocrine interference of PFASs in food on children was further validated through this screening. This study provides preliminary screening results for EDCs in food and a priority list for in vitro and in vivo research.

Research Progress of Perfluoroalkyl Substances in Edible Oil-A Review

Perfluoroalkyl substances (PFASs) have been widely used in different types of consumer and industrial applications such as surfactants, household cleaning products, textiles, carpets, cosmetics, firefighting foams, and food packaging because of their good stability and special physicochemical properties of hydrophobicity, oleophobicity, high temperature resistance, etc. Meanwhile, PFASs are considered an emerging organic pollutant due to their persistence and potential toxicity to human health. PFASs occur in edible oil, an important component of the global diet, mainly in three ways: raw material contamination, process contamination, and migration from oil contact materials. Thus, the occurrence of PFAS in edible oils has drawn more and more attention in recent years. In this work, the pertinent literature of the last two decades from the Web of Science database was researched. This review systematically addressed the potential sources, the contamination levels, and the progress of the determination of PFASs in edible oil. It aims to provide a relatively whole profile of PFASs in edible oil, render assistance to minimise human exposure to PFASs, and standardise the detection methods of perfluoroalkyl substances in edible oil.

Liver and cardiometabolic markers and conditions in a cross-sectional study of three Australian communities living with environmental per- and polyfluoroalkyl substances contamination

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) have been associated with higher cholesterol and liver function markers in some studies, but the evidence for specific cardiometabolic conditions has been inconclusive.

OBJECTIVES

We quantified the associations of single and combined PFAS with cardiometabolic markers and conditions in a cross-sectional study of three Australian communities with PFAS-contaminated water from the historical use of aqueous film-forming foam in firefighting activities, and three comparison communities.

METHODS

Participants gave blood samples for measurement of nine PFAS, four lipids, six liver function markers, and completed a survey on sociodemographic characteristics and eight cardiometabolic conditions. We estimated differences in mean biomarker concentrations per doubling in single PFAS concentrations (linear regression) and per interquartile range increase in the PFAS mixture (Bayesian kernel machine regression). We estimated prevalence ratios of biomarker concentrations outside reference limits and self-reported cardiometabolic conditions (Poisson regression).

RESULTS

We recruited 881 adults in exposed communities and 801 in comparison communities. We observed higher mean total cholesterol with higher single and mixture PFAS concentrations in blood serum (e.g., 0.18 mmol/L, 95% credible interval -0.06 to 0.42, higher total cholesterol concentrations with an interquartile range increase in all PFAS concentrations in Williamtown, New South Wales), with varying certainty across communities and PFAS. There was less consistency in direction of associations for liver function markers. Serum perfluorooctanoic acid (PFOA) concentrations were positively associated with the prevalence of self-reported hypercholesterolemia in one of three communities, but PFAS concentrations were not associated with self-reported type II diabetes, liver disease, or cardiovascular disease.

DISCUSSION

Our study is one of few that has simultaneously quantified the associations of blood PFAS concentrations with multiple biomarkers and cardiometabolic conditions in multiple communities. Our findings for total cholesterol were consistent with previous studies; however, substantial uncertainty in our estimates and the cross-sectional design limit causal inference.

Exposure to per- and polyfluoroalkyl substances in early pregnancy, risk of gestational diabetes mellitus, potential pathways, and influencing factors in pregnant women: A nested case-control study

Although previous studies have reported an association between maternal serum perfluoroalkyl substance (PFAS) exposure and gestational diabetes mellitus (GDM) risk, results have been inconsistent. Few studies have focused on the combined effects of emerging and legacy PFASs on glucose homeostasis while humans are always exposed to multiple PFASs simultaneously. Moreover, the potential pathways by which PFAS exposure induces GDM are unclear. A total of 295 GDM cases and 295 controls were enrolled from a prospective cohort of 2700 pregnant women in Shanghai, China. In total, 16 PFASs were determined in maternal spot serum samples in early pregnancy. We used conditional logistic regression, multiple linear regression, and Bayesian kernel machine regression (BKMR) to examine individual and joint effects of PFAS exposure on GDM risk and oral glucose tolerance test outcomes. The mediating effects of maternal serum biochemical parameters, including thyroid and liver function were further assessed. Maternal perfluorooctanoic acid (PFOA) exposure was associated with an increased risk of GDM (odds ratio (OR) = 1.68; 95% confidence interval (95% CI): 1.10, 2.57), consistent with higher concentrations in GDM cases than controls. Based on mediation analysis, an increase in the free triiodothyronine to free thyroxine ratio partially explained the effect of this association. For continuous glycemic outcomes, positive associations were observed between several PFASs and 1-h and 2-h glucose levels. In BKMR, PFAS mixture exposure showed a positive trend with GDM incidence, although the CIs were wide. These associations were more pronounced among women with normal pre-pregnancy body mass index (BMI). Mixed PFAS congeners may affect glucose homeostasis by increasing 1-h glucose levels, with perfluorononanoic acid found to be a main contributor. Exposure to PFASs was associated with increased risk of GDM and disturbance in glucose homeostasis, especially in normal weight women. The PFAS-associated disruption of maternal thyroid function may alter glucose homeostasis.

Sex-specific effect of perfluoroalkyl substances exposure on liver and thyroid function biomarkers: A mixture approach

Although studies have investigated the effects of perfluoroalkyl substances (PFASs) on liver and thyroid function, little is known about its combined and sex-specific effect. A total of 688 participants were interviewed and serum PFASs concentration was measured using liquid chromatography/mass spectrometry. Five biomarkers of liver and thyroid function (ALT, GGT, TSH, FT3 and FT4) were chosen as outcomes. A restriction cubic spline function was applied to capture the dose-response relationship between PFASs and liver enzymes and thyroid hormones. Multivariable regression and Bayesian kernel machine regression (BKMR) models were performed to assess the single and overall associations of PFASs with targeted biomarkers. Single-pollutant analyses indicated that increased PFASs concentrations were associated with elevated ALT and GGT levels. BKMR models suggested positive dose-response relationships between PFASs mixtures and ALT and GGT levels. Significant associations were only detected between several PFASs and thyroid hormones, and joint effect of PFASs mixtures on FT3 levels was found at higher concentrations. Meanwhile, sex differences were found in the associations of PFASs with ALT and GGT levels, with significant results only in males. Our findings provide epidemiological evidence for combined and sex-specific effects of PFASs on ALT and GGT levels.

Associations between Per- and Polyfluoroalkyl Substances Exposures and Blood Lipid Levels among Adults-A Meta-Analysis

BACKGROUND

Associations between per- and polyfluoroalkyl substances (PFAS) and blood lipid levels in humans were mixed.

OBJECTIVES

The objective of this meta-analysis was to summarize associations between PFAS and blood lipids in adults.

METHODS

A literature search was conducted on PubMed and Web of Science for articles published through 13 May 2022 that examined associations between PFAS and blood lipids, including total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triacylglycerols (TGs). Inclusion criteria included the presence of associations between five PFAS (PFOA, PFOS, PFHxS, PFDA, and PFNA) and four blood lipid measures (TC, HDL-C, LDL-C, and TGs) in adults. Data on study characteristics and PFAS-lipid associations were extracted. Assessments of individual study quality were performed. Associations of changes of blood lipid levels corresponding to 1 interquartile range (IQR)-unit increase of blood PFAS levels were pooled using random effects models. Dose-response relationships were examined.

RESULTS

Twenty-nine publications were included in the present analyses. Every IQR increase of PFOA was significantly associated with a 2.1 -mg / dL increase in TC (95% CI: 1.2, 3.0), a 1.3 -mg / dL increase in TGs (95% CI: 0.1, 2.4), and a 1.4 -mg / dL increase in LDL-C (95% CI: 0.6, 2.2). PFOS was also significantly associated with TC and LDL-C levels, and the corresponding values were 2.6 (95% CI: 1.5, 3.6) and 1.9 (95% CI: 0.9, 3.0), respectively. Associations of PFOS and PFOA with HDL-C levels were largely null. For minor PFAS species, PFHxS was significantly associated with higher levels of HDL-C [0.8 (95% CI: 0.5, 1.2)]. Inverse associations were observed between PFDA and TGs [- 5.0 (95% CI: - 8.1 , - 1.9 )] and between PFNA and TGs [- 1.7 (95% CI: - 3.5 , - 0.02 )], whereas a positive association was observed between PFDA and HDL-C [1.4 (95% CI: 0.1, 2.7)]. Nonsignificant nonlinear dose-response relationships were identified for associations of PFOA and PFOS with certain blood lipids.

DISCUSSION

PFOA and PFOS were significantly associated with TC and LDL-C levels in adults. Whether these findings may translate into an elevated cardiovascular disease risk associated with PFAS exposure warrants further investigation. https://doi.org/10.1289/EHP11840.

A review of cardiovascular effects and underlying mechanisms of legacy and emerging per- and polyfluoroalkyl substances (PFAS)

Cardiovascular disease (CVD) poses the leading threats to human health and life, and their occurrence and severity are associated with exposure to environmental pollutants. Per- and polyfluoroalkyl substances (PFAS), a group of widely used industrial chemicals, are characterized by persistence, long-distance migration, bioaccumulation, and toxicity. Some PFAS, particularly perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorohexanesulfonic acid (PFHxS), have been banned, leaving only legacy exposure to the environment and human body, while a number of novel PFAS alternatives have emerged and raised concerns, such as polyfluoroalkyl ether sulfonic and carboxylic acid (PFESA and PFECA) and sodium p-perfluorous nonenoxybenzene sulfonate (OBS). Overall, this review systematically elucidated the adverse cardiovascular (CV) effects of legacy and emerging PFAS, emphasized the dose/concentration-dependent, time-dependent, carbon chain length-dependent, sex-specific, and coexposure effects, and discussed the underlying mechanisms and possible prevention and treatment. Extensive epidemiological and laboratory evidence suggests that accumulated serum levels of legacy PFAS possibly contribute to an increased risk of CVD and its subclinical course, such as cardiac toxicity, vascular disorder, hypertension, and dyslipidemia. The underlying biological mechanisms may include oxidative stress, signaling pathway disturbance, lipid metabolism disturbance, and so on. Various emerging alternatives to PFAS also play increasingly prominent toxic roles in CV outcomes that are milder, similar to, or more severe than legacy PFAS. Future research is recommended to conduct more in-depth CV toxicity assessments of legacy and emerging PFAS and explore more effective surveillance, prevention, and treatment strategies, accordingly.

Cooking methods effectively alter perfluoroalkyl substances and nutrients in cultured and wild bullfrogs

The ubiquitous distribution of perfluoroalkyl substances (PFASs) poses a threat to the health of aquatic organisms and humans. Bullfrogs are considered a popular aquatic food product in South China, providing high protein and tasty cuisine; however bullfrogs have been shown to contain significant concentrations of PFASs. However, the risk-benefit ratios of PFASs and nutrient contents in cooked bullfrogs are not well understood. PFASs and nutrients were investigated in raw and cooked specimens of cultured and wild bullfrogs in this study. Novel PFASs showed higher detection levels and accumulation in wild bullfrogs than in cultured bullfrogs. Potential factors such as fat and fatty acid ratio affected PFASs accumulation in different tissues and by different cooking methods of bullfrogs. All cooking methods can reduce PFASs in edible tissues while significantly enhancing the nutritive value index (NVI) compared to raw bullfrogs. Steaming was the most effective way to reduce PFASs (rate of reduction was over 66%) and resulted in a lower risk of contributing to arteriosclerosis than other cooking methods assessed by atherogenicity index (AI) values. Cultured bullfrogs instead of wild bullfrogs were recommended for human consumption, and steaming was regarded as a better cooking method in terms of risk-benefit concerns. Overall, this work provides quantitative analysis of cooking methods that alter PFASs and nutrients in bullfrogs.

Recent advances in the remediation of perfluoroalkylated and polyfluoroalkylated contaminated sites

Per- and polyfluoroalkyl substances (PFASs) are compounds used since 1940 in various formulations in the industrial and consumer sectors due to their high chemical and thermal stability. In recent years, PFASs have caused global concern due to their presence in different water and soil matrices, which threatens the environment and human health. These compounds have been reported to be linked to the development of serious human diseases, including but not limited to cancer. For this reason, PFASs have been considered as persistent organic compounds (COPs) and contaminants of emerging concern (CECs). Therefore, this work aims to present the advances in remediation of PFASs-contaminated soil and water by addressing the current literature. The performance and characteristics of each technique were addressed deeply in this work. The reviewed literature found that PFASs elimination studies in soil and water were carried out at a laboratory and pilot-scale in some cases. It was found that ball milling, chemical oxidation and thermal desorption are the most efficient techniques for the removal of PFASs in soils, however, phyto-microbial remediation is under study, which claims to be a promising technique. For the remediation of PFASs-contaminated water, the processes of electrocoagulation, membrane filtration, ozofractionation, catalysis, oxidation reactions - reduction, thermolysis and destructive treatments with plasma have presented the best results. It is noteworthy that hybrid treatments have also proved to be efficient techniques in the removal of these contaminants from soil and water matrices. Therefore, the improvisation and implication of existing techniques on a field-scale are greatly warranted to corroborate the yields obtained on a pilot- and laboratory-scale.

Perfluorooctanoic acid and perfluorooctanesulfonic acid induce immunotoxicity through the NF-κB pathway in black-spotted frog (Rana nigromaculata)

Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are widely detected in the environment and wild animals, thus posing a threat to wildlife and public health; however, knowledge about their immunotoxicity and the underlying mechanism remains limited. In the present study, male black-spotted frogs (Rana nigromaculata) were exposed to environmentally relevant concentrations (0, 1, and 10 μg/L) of PFOA or PFOS for 21 days; subsequently, biochemical analysis, molecular docking, and gene expression determination were conducted. The results indicated that exposure to 10 μg/L PFOA decreased the serum levels of immunoglobulin A. PFOS exposure significantly increased the hepatic levels of interleukin-1β, interleukin-6, tumor necrosis factor-α, interferon-γ, and nitric oxide; but PFOA significantly increased the levels of only tumor necrosis factor-α. Furthermore, PFOA and PFOS exposure significantly decreased the activity of inducible nitric oxide synthase and total nitric oxide synthase. IBRv2 analysis indicated that PFOA and PFOS had a similar effect on these immune indicators, but PFOS was more toxic than PFOA. Molecular docking revealed that PFOA and PFOS can bind to nuclear factor-κB (NF-κB) by forming stable hydrogen bonds. PFOA and PFOS exposure upregulated the gene expression of NF-κB and its downstream genes. Significant correlations between the expression of genes involved in the NF-κB pathway and immune-related indicators suggests that PFOA- and PFOS-induced immunotoxicity was associated with the activation of NF-κB. Our findings provide novel insights into the potential role of NF-κB in immunotoxicity induced by PFOA and PFOS in frogs.

Serum per- and polyfluoroalkyl substances and abnormal lipid metabolism: A nationally representative cross-sectional study

BACKGROUND

The associations of legacy per- and polyfluoroalkyl substances (PFAS) with lipid metabolism are controversial, and there is little information about the impact of emerging PFAS (6:2 Cl-PFESA) on lipid metabolism in China.

OBJECTIVES

We aimed to explore the associations of legacy and emerging PFAS with lipid profiles and dyslipidemia in Chinese adults.

METHODS

We included 10,855 Chinese participants aged 18 years and above in the China National Human Biomonitoring. The associations of 8 PFAS with 5 lipid profiles and 4 dyslipidemia were investigated using weighted multiple linear regression or weighted logistic regression, and the dose-response associations were investigated using restricted cubic spline model.

RESULTS

Among the 8 PFAS, the concentration of PFOS was the highest, with a geometric mean of 5.15 ng/mL, followed by PFOA and 6:2 Cl-PFESA, which were 4.26 and 1.63 ng/mL, respectively. Legacy (PFOA, PFOS, PFUnDA) or emerging (6:2 Cl-PFESA) PFAS were associated with lipid profiles (TC, LDL-C, HDL-C, non HDL-C) and dyslipidemia (high LDL-C, high TC, low HDL-C), and their effects on TC were most obvious. TC concentration increased by 0.595 mmol/L in the highest quartile (Q4) of PFOS when compared with the lowest quartile (Q1), (95 % CI:0.396, 0.794). Restricted cubic spline models showed that PFAS are nonlinearly associated with TC, non HDL-C, LDL-C and HDL-C, and that the lipid concentrations tend to be stable when PFOS and PFOA were > 20 ng/mL well as when the 6:2 Cl-PFESA level was > 10 ng/mL. The positive associations between PFAS mixtures and lipid profiles were also significant.

CONCLUSIONS

Single and mixed exposure to PFAS were positively associated with lipid profiles, and China's unique legacy PFAS substitutes (6:2 Cl-PFESA) contributed less to lipid profiles than legacy PFAS. In the future, cohort studies will be needed to confirm our findings.

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

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

Association between per- and polyfluoroalkyl substances exposure and risk of diabetes: a systematic review and meta-analysis

BACKGROUND

Emerging evidence suggests that per- and polyfluoroalkyl substances (PFAS) are endocrine disruptors and may contribute to the etiology of diabetes.

OBJECTIVES

This study aimed to systematically review the epidemiological evidence on the associations of PFAS with mortality and morbidity of diabetes and to quantitatively evaluate the summary effect estimates of the existing literature.

METHODS

We searched three electronic databases for epidemiological studies concerning PFAS and diabetes published before April 1, 2022. Summary odds ratio (OR), hazard ratio (HR), or β and their 95% confidence intervals (CIs) were respectively calculated to evaluate the association between PFAS and diabetes using random-effects model by the exposure type, and dose-response meta-analyses were also performed when possible. We also assessed the risk of bias of the studies included and the confidence in the body of evidence.

RESULTS

An initial literature search identified 1969 studies, of which 22 studies were eventually included. The meta-analyses indicated that the observed statistically significant PFAS-T2DM associations were consistent in cohort studies, while the associations were almost non-significant in case-control and cross-sectional studies. Dose-response meta-analysis showed a "parabolic-shaped" association between perfluorooctanoate acid (PFOA) exposure and T2DM risk. Available evidence was rated with "low" risk of bias, and the level of evidence for PFAS and incident T2DM was considered "moderate".

CONCLUSIONS

Our findings suggest that PFAS exposure may increase the risk of incident T2DM, and that PFOA may exert non-monotonic dose-response effect on T2DM risk. Considering the widespread exposure, persistence, and potential for adverse health effects of PFAS, further cohort studies with improvements in expanding the sample size, adjusting the covariates, and considering different types of PFAS exposure at various doses, are needed to elucidate the putative causal associations and potential mode of action of different PFAS on diabetes.

IMPACT STATEMENT

A growing body of evidence suggests that per- and polyfluoroalkyl substances (PFAS) are endocrine disruptors and may contribute to the development of diabetes. However, epidemiological evidence on the associations of PFAS and diabetes is inconsistent. We performed this comprehensive systematic review and meta-analysis to quantitatively synthesize the evidence. The findings of this study suggest that exposure to PFAS may increase diabetes risk among the general population. Reduced exposure to these "forever and everywhere chemicals" may be an important preventative approach to reducing the risk of diabetes across the population.

Integration of metabolomics and proteomics reveals the underlying hepatotoxic mechanism of perfluorooctane sulfonate (PFOS) and 6:2 chlorinated polyfluoroalkyl ether sulfonic acid (6:2 Cl-PFESA) in primary human hepatocytes

Perfluorooctane sulfonate (PFOS) and its alternative 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) are ubiquitous in various environmental and human samples. They have been reported to have hepatotoxicity effects, but the potential mechanisms remain unclear. Herein, we integrated metabolomics and proteomics analysis to investigate the altered profiles in metabolite and protein levels in primary human hepatocytes (PHH) exposed to 6:2 Cl-PFESA and PFOS at human exposure relevant concentrations. Our results showed that 6:2 Cl-PFESA exhibited higher perturbation effects on cell viability, metabolome and proteome than PFOS. Integration of metabolomics and proteomics revealed that the alteration of glycerophospholipid metabolism was the critical pathway of 6:2 Cl-PFESA and PFOS-induced lipid metabolism disorder in primary human hepatocytes. Interestingly, 6:2 Cl-PFESA-induced cellular metabolic process disorder was associated with the cellular membrane-bounded signaling pathway, while PFOS was associated with the intracellular transport process. Moreover, the disruption effects of 6:2 Cl-PFESA were also involved in inositol phosphate metabolism and phosphatidylinositol signaling system. Overall, this study provided comprehensive insights into the hepatic lipid toxicity mechanisms of 6:2 Cl-PFESA and PFOS in human primary hepatocytes.

Perfluoroalkyl substances and lipid concentrations in the blood: A systematic review of epidemiological studies

BACKGROUND

Perfluoroalkyl substances (PFAS) are widely used synthetic aliphatic compounds. This systematic review aims to assess PFAS associations with low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), total cholesterol (TC) and total triglyceride (TG) concentrations in human populations.

METHOD

We systematically searched four online databases, PubMed, Scopus, Embase, and Cochrane Library for relevant peer-reviewed English language articles published until July 2021. Additional relevant articles identified were also included in the search results. We categorised populations into adults (≥18 years old) and children. Primary findings were the associations between PFAS concentrations and LDL, HDL, TC, and TG concentrations in the serum, plasma, or whole blood; secondary findings were the associations between PFAS concentrations and the odds of lipid-related health outcomes. Quantitative synthesis was done by vote counting of the effect directions between concentrations of PFAS and lipids/health outcomes, repeated on articles with sample size >1000. Sign tests were performed to assess the statistical significance of the differences between positive and negative associations. Sensitivity analysis was performed by separating out articles with populations having high concentrations of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). Quality was assessed with the STROBE checklist and NHBLI Study Quality Assessment Tool.

RESULTS

A total of 58 articles were included for review. There was evidence that PFAS exposure is associated with higher concentrations of LDL, HDL, and TC, particularly for PFOA-LDL, PFOA-TC, PFOS-TC, and PFNA-LDL. Associations between PFAS and TG tended to be negative, especially for perfluoroundecanoic acid (PFUnDA). Associations between PFAS concentration and the odds of secondary outcomes generally supported a positive association between PFAS and cholesterol concentrations.

CONCLUSION

We found evidence of associations between the concentrations of some PFAS-lipid pairs in human populations. Future research should be conducted on the less well-studied PFAS to explore their effects on human health and in regions where such studies are currently lacking. (300 words).

Assessing the hepatotoxicity of PFOA, PFOS, and 6:2 Cl-PFESA in black-spotted frogs (Rana nigromaculata) and elucidating potential association with gut microbiota

Pollution caused by per- and polyfluoroalkyl substances (PFASs) has become a major global concern. The association between PFAS-induced hepatotoxicity and gut microbiota in amphibians, particularly at environmentally relevant concentrations, remains elusive. Herein we exposed male black-spotted frogs (Rana nigromaculata) to 1 and 10 μg/L waterborne perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), and 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) for 21 days; subsequently, liver histopathological, oxidative stress, molecular docking, gene/protein expression, and gut microbiome analyses were conducted. PFOS and 6:2 Cl-PFESA exposure enhanced serum alanine aminotransferase and aspartate aminotransferase activities, and markedly increased hepatic area of vacuoles and inflammatory cell infiltration, while PFOA exposure increased serum alanine aminotransferase but not aspartate aminotransferase activities and affected hepatic area of vacuoles and inflammatory cell infiltration to a lesser extent. All three PFASs elevated catalase, glutathione S-transferase, and glutathione peroxidase activities and glutathione and malondialdehyde contents in the liver, suggesting the induction of oxidative stress. Further, PFASs could bind to mitogen-activated protein kinases (p38, ERK, and JNK), upregulating not only their expression but also the expression of downstream oxidative stress-related genes and that of P-p38, P-ERK, and Nrf2 proteins. In addition, PFAS exposure significantly increased the relative abundance of Proteobacteria and Delftia and decreased that of Firmicutes and Dietzia, Mycoplasma, and Methylobacterium-Methylorubrum in the order of PFOS ≈ 6:2 Cl-PFESA > PFOA. Altogether, it appears that PFOS and 6:2 Cl-PFESA are more toxic than PFOA. Finally, microbiota function prediction, microbiota co-occurrence network, and correlation analysis between gut microbiota and liver indices suggested that PFAS-induced hepatotoxicity was associated with gut microbiota dysbiosis. Our data provide new insights into the role of gut microbiota in PFAS-induced hepatotoxicity in frogs.

Associations between Mixture of Perfluoroalkyl Substances and Lipid Profile in a Highly Exposed Adult Community in the Veneto Region

BACKGROUND

Residents of a large area in the Veneto Region (Northeastern Italy) were exposed to drinking water contaminated by perfluoroalkyl substances (PFAS) for decades. While exposure to PFAS has been consistently associated with elevated serum lipids, combined exposures to multiple PFASs have been poorly investigated. Utilising different statistical approaches, we examine the association between chemical mixtures and lipid parameters.

METHODS

Cross-sectional data from the regional health surveillance program (34,633 individuals aged 20-64 years) were used to examine the combined effects of PFAS mixture (Perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoic acid (PFNA) and perfluorohexane sulfonate (PFHxS)) on total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C). Weighted Quantile Sum (WQS) regression, Quantile-based G-computation (Q-Gcomp) and Bayesian Kernel Machine Regression (BKMR) were used based on their ability to handle highly correlated chemicals.

RESULTS

We observed that each quartile increase in the WQS index was associated with an increase in the levels of TC (β: 4.09, 95% CI: 3.47-4.71), HDL-C (β: 1.13, 95% CI: 0.92-1.33) and LDL-C (β: 3.14, 95% CI: 2.65-3.63). Q-Gcomp estimated that a quartile increase in the PFAS mixture was associated with increased TC (ψ: 4.04, 95% CI 3.5-4.58), HDL-C (ψ: 1.07, 95% CI 20.87-1.27) and LDL-C (ψ: 2.71, 95% CI 2.23-3.19). In the BKMR analysis, the effect of PFAS mixture on serum lipids increased significantly when their concentrations were at their 75th percentiles or above, compared to those at their 50th percentile. All methods revealed a major contribution of PFOS and PFNA, although the main exposure was due to PFOA. We found suggestive evidence that associations varied when stratified by gender.

CONCLUSIONS

The PFAS mixture was positively associated with lipid parameters, regardless of the applied method. Very similar results obtained from the three methods may be attributed to the linear positive association with the outcomes and no interaction between each PFAS.

Health-related toxicity of emerging per- and polyfluoroalkyl substances: Comparison to legacy PFOS and PFOA

Per- and polyfluoroalkyl substances (PFAS) are highly persistent, manufactured chemicals used in various manufacturing processes and found in numerous commercial products. With over 9000 compounds belonging to this chemical class, there is increasing concern regarding human exposure to these compounds due to their persistent, bioaccumulative, and toxic nature. Human exposure to PFAS may occur from a variety of exposure sources, including, air, food, indoor dust, soil, water, from the transfer of PFAS from non-stick wrappers to food, use of cosmetics, and other personal care products. This critical review presents recent research on the health-related impacts of PFAS exposure, highlighting compounds other than Perfluorooctanoic acid (PFOA) and Perfluoroctane sulfonate (PFOS) that cause adverse health effects, updates the current state of knowledge on PFAS toxicity, and, where possible, elucidates cause-and-effect relationships. Recent reviews identified that exposure to PFAS was associated with adverse health impacts on female and male fertility, metabolism in pregnancy, endocrine function including pancreatic dysfunction and risk of developing Type 2 diabetes, lipid metabolism and risk of childhood adiposity, hepatic and renal function, immune function, cardiovascular health (atherosclerosis), bone health including risk for dental cavities, osteoporosis, and vitamin D deficiency, neurological function, and risk of developing breast cancer. However, while cause-and-effect relationships for many of these outcomes were not able to be clearly elucidated, it was identified that 1) the evidence derived from both animal models and humans suggested that PFAS may exert harmful impacts on both animals and humans, however extrapolating data from animal to human studies was complicated due to differences in exposure/elimination kinetics, 2) PFAS precursor kinetics and toxicity mechanism data are still limited despite ongoing exposures, and 3) studies in humans, which provide contrasting results require further investigation of the long-term-exposed population to better evaluate the biological toxicity of chronic exposure to PFAS.

Per- and polyfluoroalkyl substances (PFASs) in groundwater from a contaminated site in the North China Plain: Occurrence, source apportionment, and health risk assessment

Per-and polyfluoroalkyl substances (PFASs) are manmade chemicals that have wide industrial and commercial application. However, little research has been carried out on PFASs pollution in groundwater from a previously contaminated site. Here, we investigated 43 PFASs in a monitoring campaign from two different aquifers in the North China Plain. Our results revealed that total PFASs concentrations (∑₄₃PFASs) ranged from 0.22 to 3,776.76 ng/L, with no spatial or compositional differences. Moreover, perfluorooctanoic acid (PFOA) and perfluoroheptane sulfonate (PFHpS) were the dominant pollutants with mean concentrations of 177.33 ng/L and 51 ng/L, respectively. ∑₄₃PFAS decreased with well depth due to the adsorption of PFASs to the aquifer materials. Water temperature, total organic carbon, dissolved oxygen, and total phosphorus concentrations were correlated to the PFAS concentrations. Principal component analysis indicated that the main sources of PFASs in groundwater were untreated industrial discharge, untreated domestic wastewater, food packaging, aqueous film forming foams and metal plating, and surface runoff, which overlapped with the industries that previously existed in a nearby city. Human health risks from drinking contaminated groundwater were low to the local residents, with children aged 1-2 years being the most sensitive group. One specific site with a high PFOA concentration was of concern, as it was several orders higher than the 70 ng/L recommended by US Environmental Protection Agency health advisory. This study provided baseline data for PFASs in a previously-contaminated site, which will help in the development of effective strategies for controlling PFASs pollution in the North China Plain.

Exploring the origin of efficient adsorption of poly- and perfluoroalkyl substances in household point-of-use water purifiers: Deep insights from a joint experimental and computational study

Poly- and perfluoroalkyl substances (PFAS) are harmful chemicals to humans and widely detected in water bodies including tap water. PFAS cannot be efficiently removed from water through conventional treatment processes used in full-scale drinking water treatment plants, posing a latent risk to human health via drinking tap water. Here in-field investigations show that the household point-of-use (POU) water purifiers constituted with coconut shell activated carbon can achieve 21%-99% removal for 14 legacy and emerging PFAS in tap water based on the ratio of influent and effluent. Extensive characterizations combine with chemical analyses demonstrate that physical adsorption based on Van der Waals force can remove 23 PFAS from tap water, wherein the hydrophobicity of PFAS is the crucial factor. Density functional theory calculations together with the quantitative structure-activity relationship model confirm that both topological structures as well as hydrophobicity of PFAS and electrostatic interactions between the strong electronegative F atoms and the adsorbent surface are the most critical factors controlling the PFAS adsorption to activated carbon. Overall, our results offer insights into the molecular mechanisms that enable the adsorption of PFAS in POU filters.

Per- and polyfluoroalkyl substances and incident diabetes in midlife women: the Study of Women's Health Across the Nation (SWAN)

AIMS/HYPOTHESIS

Diabetogenic effects of per- and polyfluoroalkyl substances (PFAS) have been suggested. However, evidence based on prospective cohort studies is limited. We examined the association between serum PFAS concentrations and incident diabetes in the Study of Women's Health Across the Nation Multi-Pollutant Study (SWAN-MPS).

METHODS

We included 1237 diabetes-free women aged 45-56 years at baseline (1999-2000) who were followed up to 2017. At each follow-up visit, women with incident diabetes were identified by the presence of one or more of the following conditions: (1) use of a glucose-lowering medication at any visit; (2) fasting glucose ≥7 mmol/l on two consecutive visits while not on steroids; and (3) any two visits with self-reported diabetes and at least one visit with fasting blood glucose ≥7 mmol/l. Serum concentrations of 11 PFAS were quantified by online solid-phase extraction-HPLC-isotope dilution-tandem MS. Seven PFAS with high detection rates (>96%) (n-perfluorooctanoic acid [n-PFOA], perfluorononanoic acid [PFNA], perfluorohexane sulfonic acid [PFHxS], n-perfluorooctane sulfonic acid [n-PFOS], sum of perfluoromethylheptane sulfonic acid isomers [Sm-PFOS], 2-[N-methyl-perfluorooctane sulfonamido] acetic acid [MeFOSAA] and 2-[N-ethyl-perfluorooctane sulfonamido] acetic acid) were included in data analysis. Cox proportional hazards models were used to compute HRs and 95% CIs. Quantile-based g-computation was used to evaluate the joint effects of PFAS mixtures.

RESULTS

After adjustment for race/ethnicity, site, education, smoking status, alcohol consumption, total energy intake, physical activity, menopausal status and BMI, the HR (95% CI) comparing the lowest with the highest tertile was 1.67 (1.21, 2.31) for n-PFOA (p_trend = 0.001), 1.58 (1.13, 2.21) for PFHxS (p_trend = 0.003), 1.36 (0.97, 1.90) for Sm-PFOS (p_trend = 0.05), 1.85 (1.28, 2.67) for MeFOSAA (p_trend = 0.0004) and 1.64 (1.17, 2.31) for the sum of four common PFAS (n-PFOA, PFNA, PFHxS and total PFOS) (p_trend = 0.002). Exposure to seven PFAS as mixtures was associated with an HR of 2.62 (95% CI 1.12, 6.20), comparing the top with the bottom tertiles for all seven PFAS.

CONCLUSIONS/INTERPRETATION

This study suggests that PFAS may increase diabetes risk in midlife women. Reduced exposure to these 'forever and everywhere chemicals' may be an important preventative approach to lowering population-wide diabetes risk.

Association of emerging and legacy per- and polyfluoroalkyl substances with unexplained recurrent spontaneous abortion

Emerging per- and polyfluoroalkyl substances (PFAS) alternatives are increasingly used in daily life. Although legacy PFAS have been associated with miscarriage in previous studies, it remains unknown whether exposure to emerging and legacy PFAS has any impact on the risk of unexplained recurrent spontaneous abortion (URSA). We conducted a case-control study with 464 URSA cases who had at least 2 unexplained miscarriages and 440 normal controls who had at least one normal livebirth. Concentrations of 21 PFAS in plasma, including three emerging PFAS alternatives, eight linear and branched PFAS isomers, four short-chain PFAS, and six legacy PFAS, were measured by ultra-performance liquid chromatography coupled with a tandem mass spectrometry (UPLC-MS/MS). Multiple logistic regression was applied to evaluate the relationship between PFAS and URSA risk. Perfluorooctanoic acid (PFOA, median: 6.18 ng/mL), perfluorooctane sulfonate (PFOS, median: 4.10 ng/mL), and 6:2 chlorinated perfluoroalkyl ether sulfonic acid (6:2 Cl-PFESA, median: 2.27 ng/mL) were the predominant PFAS in the controls. Exposure to 6:2 Cl-PFESA [adjusted odds ratio (aOR) = 1.18 (95% CI: 1.00, 1.39)] and hexafluoropropylene oxide dimer acid (HFPO-DA) [aOR = 1.35 (95% CI: 1.15, 1.59)] were significantly associated with increased risks of URSA. Women with older age (>30 years old) had a stronger association between PFAS and URSA. Our results suggest that emerging PFAS alternatives may be an important risk factor for URSA.

Exploring the source, migration and environmental risk of perfluoroalkyl acids and novel alternatives in groundwater beneath fluorochemical industries along the Yangtze River, China

The widely used legacy perfluoroalkyl acids (PFAAs) with serious environmental hazards are gradually restricted and being replaced by novel alternatives. Here, for an efficient control of emerging environmental risks in groundwater, we systematically studied the source apportionment, spatial attenuation, composition change and risk zoning of 12 PFAAs and five novel alternatives within a region of ~200 km² around a mega fluorochemical industrial park (FIP) along the Yangtze River, and in-depth explored potential association between groundwater and soil pollution as well as influencing factors on contaminant migration and risk distribution in the aquifer. Short-chain PFAAs and novel alternatives together accounted for over 70% in groundwater, revealing their prevalence in replacing legacy perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Novel alternatives for PFOA were mainly hexafluoropropylene oxide dimer acid (GenX) and hexafluoropropylene oxide trimer acid (HFPO-TA), while those for PFOS were 6:2 chlorinated polyfluorinated ether sulfonic acid (6:2 Cl-PFESA) and 6:2 fluorotelomer sulfonic acid (6:2 FTS). PFAAs (maximum total: 1339 ng/L) and novel alternatives (maximum total: 208 ng/L) in groundwater were mostly derived from the FIP, and exhibited an exponentially decreasing trend with increasing distance. Compared with those in groundwater, more diverse sources of PFAAs and novel alternatives in surface soil were identified. The transport of these chemicals may be retarded by clayed surface soils with high organic matter contents. High aquifer permeability could generally promote the dilution and migration of PFAAs and novel alternatives in groundwater, as well as reduce the differences in their spatial distribution. Shorter-chain components with smaller molecules and higher hydrophilicity exhibited greater migration capacities in the aquifer. In addition, different levels of health risk from PFOS and PFOA were zoned based on drinking groundwater, and high risks tended to be distributed in areas with relatively poor aquifer water yield due to higher pollutant accumulation.

Human exposure to F-53B in China and the evaluation of its potential toxicity: An overview

Chlorinated polyfluoroalkyl ether sulfonic acid (Cl-PFESAs, trade name F-53B), an alternative to perfluorooctane sulfonate (PFOS), has been widely used as a mist suppressant in the Chinese electroplating industry since the 1970 s. Due to greater restrictions on PFOS globally in recent years, the production and use of F-53B correspondingly increased, consequently causing more emissions into the environment. In China, an increasing number of studies report frequent detection and broad exposure to F-53B in the natural environment, various wildlife and the human body. In human blood, the detection rate of F-53B is almost 80%, accounting for 8.69 to 28% of ∑per- and polyfluoroalkyl substances (PFASs). F-53B is the most biopersistent PFAS in humans to date, with a half-life of 15.3 years. In addition, F-53B displays protein binding affinity and high human placental permeability. Recently, some epidemiological studies have reported the health risks associated with F-53B in humans, including abnormal serum lipid metabolism, vascular dysfunction, endocrine disorders and even adverse birth outcomes. Various in vivo and in vitro studies have demonstrated the toxicity of F-53B, such as hepatotoxicity, interference effects on the endocrine system, as well as reproductive and developmental toxicity. Our aims are to review studies on human F-53B exposure levels, trends and associated health effects; evaluate the potential toxicity; and predict directions for future research.

Source apportionment and crop bioaccumulation of perfluoroalkyl acids and novel alternatives in an industrial-intensive region with fluorochemical production, China: Health implications for human exposure

Due to their great environmental hazards, the widely used legacy perfluoroalkyl acids (PFAAs) are gradually restricted, and novel alternatives are being developed and applied. For efficient control of emerging environmental risks in agricultural production, we systematically studied the source apportionment in field soils and bioaccumulation characteristics in multiple crops of 12 PFAAs and five novel alternatives in an industrial-intensive region of China, followed by human exposure estimation and health risk assessment. Compared with perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), shorter-chained PFAAs and novel alternatives have become the dominant components in local soils and crops, indicating their wide application. A positive matrix factorization (PMF) model coupled with multivariate analysis identified fluoropolymer manufacturing and textile treatment as the principal sources. The bioaccumulation factors (BAFs) of individual PFAAs and alternatives in crops decreased with increasing carbon chain lengths. As a novel alternative of PFOA, hexafluoropropylene oxide dimer acid (GenX) exhibited much higher BAFs; for the alternative of PFOS, 6:2 chlorinated polyfluorinated ether sulfonic acid (6:2 Cl-PFESA) showed lower BAFs. The bioaccumulation capacities of PFAAs and alternatives were also associated with soil organic matter and crop species. Through crop consumption, short-chained PFAAs and novel alternatives might pose emerging human health threats.

Associations between both legacy and alternative per- and polyfluoroalkyl substances and glucose-homeostasis: The Isomers of C8 health project in China

BACKGROUND

Epidemiological studies on the associations of legacy per- and polyfluoroalkyl substances (PFASs) and glucose homeostasis remain discordant. Understanding of PFAS alternatives is limited, and few studies have reported joint associations of PFASs and PFAS alternatives.

OBJECTIVES

To investigate associations of novel PFAS alternatives (chlorinated perfluoroalkyl ether sulfonic acids, Cl-PFESAs and perfluorobutanoic acid, PFBA) and two legacy PFASs (Perfluorooctanoic acid, PFOA and perfluorooctane sulfonate, PFOS) with glucose-homeostasis markers and explore joint associations of 13 legacy and alternative PFASs with the selected outcomes.

METHODS

We used cross-sectional data of 1,038 adults from the Isomers of C8 Health Project in China. Associations of PFASs and PFAS alternatives with glucose-homeostasis were explored in single-pollutant models using generalized linear models with natural cubic splines for PFASs. Bayesian Kernel Machine Regression (BKMR) models were applied to assess joint associations of exposures and outcomes. Sex-specific analyses were also conducted to evaluate effect modification.

RESULTS

After adjusting for confounders, both legacy (PFOA, PFOS) and alternative (Cl-PFESAs and PFBA) PFASs were positively associated with glucose-homeostasis markers in single-pollutant models. For example, in the total study population, estimated changes with 95% confidence intervals (CI) of fasting glucose at the 95th percentile of 6:2Cl-PFESA and PFOS against the thresholds were 0.90 (95% CI: 0.59, 1.21) and 0.44 (95% CI: 0.26, 0.62). Positive joint associations were found in BKMR models with 6:2Cl-PFESA contributing most. Sex-specific associations existed in both single- and multi-pollutant models.

CONCLUSIONS

Legacy and alternative PFASs were positively associated with glucose-homeostasis markers. 6:2Cl-PFESA was the primary contributor. Sex-specific associations were also identified. These results indicate that joint associations and effect modification should be considered in risk assessment. However, further studies are recommended to strengthen our findings and to elucidate the mechanisms of action of legacy and alternative PFASs.

Exposure to per- and polyfluoroalkyl substances (PFAS) and type 2 diabetes risk

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous man-made chemicals found in consumer products including fabrics, food packaging, non-stick coatings, and aqueous film-forming foams. PFAS are stable and extremely resistant to degradation, resulting in high persistence throughout the environment as well as in human blood. PFAS consist of a large family of synthetic chemicals, with over 4000 distinct varieties having been identified and around 250 currently being manufactured at globally relevant levels. Numerous epidemiological studies have linked exposure to PFAS with adverse health effects ranging from immunotoxicity, cardiometabolic disease, developmental and reproductive effects, cancer, and recently type 2 diabetes. Several studies have demonstrated associations between serum PFAS concentrations and glycemic indicators of type 2 diabetes including glucose, insulin, and HOMA-IR in adolescent and adult cohorts. In addition, some studies have shown positive associations with incident type 2 diabetes and multiple PFAS. However, the link between PFAS exposure and the development of diabetes continues to be a disputed area of study, with conflicting data having been reported from various epidemiological studies. In this mini review we will summarize the current state of the literature linking PFAS to type 2 diabetes and discuss important future directions including the use of more complex mixtures-based statistical analyses.