Serum concentrations of per-/polyfluoroalkyl substances and risk of type 2 diabetes: A case-control study

Prenatal Exposure to Per- and Polyfluoroalkyl Substances and ASD-Related Symptoms in Early Childhood: Mediation Role of Steroids

Previous studies regarding the associations between perfluoroalkyl and polyfluoroalkyl substances (PFAS) and autism spectrum disorder (ASD) have yielded inconsistent results, with the underlying mechanisms remaining unknown. In this study, we quantified 13 PFAS in cord serum samples from 396 neonates and followed the children at age 4 to assess ASD-related symptoms. Our findings revealed associations between certain PFAS and ASD-related symptoms, with a doubling of perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA) concentrations associated with respective increases of 1.79, 1.62, and 1.45 units in language-related symptoms and PFDA exhibiting an association with higher score of sensory stimuli. Nonlinear associations were observed in the associations of 6:2 chlorinated polyfluorinated ether sulfonate (Cl-PFAES) and 8:2 Cl-PFAES with ASD-related symptoms. Employing weighted quantile sum (WQS) regression, we observed significant mixture effects of multiple PFAS on all domains of ASD-related symptoms, with PFNA emerging as the most substantial contributor. Assuming causality, we found that 39-40% of the estimated effect of long-chain PFAS (PFUnDA and PFDoDA) exposure on sensory stimuli was mediated by androstenedione. This study provides novel epidemiological data about prenatal PFAS mixture exposure and ASD-related symptoms.

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

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

Associations of Serum Per- and Polyfluoroalkyl Substances with Hyperuricemia in Adults: A Nationwide Cross-Sectional Study

There has been widespread concern about the health hazards of per- and polyfluoroalkyl substances (PFAS), which may be the risk factor for hyperuricemia with evidence still insufficient in the general population in China. Here, we conducted a nationwide study involving 9,580 adults aged 18 years or older from 2017 to 2018, measured serum concentrations of uric acid and PFAS (PFOA, PFOS, 6:2 Cl-PFESA, PFNA, PFHxS) in participants, to assess the associations of individual PFAS with hyperuricemia, and estimated a joint effect of PFAS mixtures. We found positive associations of higher serum PFAS with elevated odds of hyperuricemia in Chinese adults, with the greatest contribution from PFOA (69.37%). The nonmonotonic dose-response (NMDR) relationships were observed for 6:2 Cl-PFESA and PFHxS with hyperuricemia. Participants with less marine fish consumption, overweight, and obesity may be the sensitive groups to the effects of PFAS on hyperuricemia. We highlight the potential health hazards of legacy long-chain PFAS (PFOA) once again because of the higher weights of joint effects. This study also provides more evidence about the NMDR relationships in PFAS with hyperuricemia and emphasizes a theoretical basis for public health planning to reduce the health hazards of PFAS in sensitive groups.

Dietary seafood as a potential modifier in the relationship between per- and polyfluoroalkyl substances (PFASs) burden and prediabetes/diabetes: Insights from a nationally representative cross-sectional study

While seafood is recognized for its beneficial effects on glycemic control, concerns over elevated levels of per- and polyfluoroalkyl substances (PFASs) may deter individuals from its consumption. This study aims to elucidate the relationship between seafood intake, PFASs exposure, and the odds of diabetes. Drawing from the China National Human Biomonitoring data (2017-2018), we assessed the impact of PFASs on the prevalence of prediabetes and diabetes across 10851 adults, including 5253 individuals (48.1%) reporting seafood consumption. Notably, seafood consumers exhibited PFASs levels nearly double those of non-consumers. Multinomial logistic regression identified significant positive associations between serum PFASs concentrations and prediabetes (T3 vs. T1: ORPFOA: 1.64 [1.08-2.49], ORPFNA: 1.59 [1.19-2.13], ORPFDA: 1.56 [1.13-2.17], ORPFHxS: 1.58 [1.18-2.12], ORPFHpS: 1.73 [1.24-2.43], ORPFOS: 1.51 [1.15-1.96], OR6:2 Cl-PFESA: 1.58 [1.21-2.07]). Significant positive association were also found between PFHpS, PFOS, and diabetes. RCS curves indicated significant non-linear relationships between log-transformed PFOA, PFUnDA, PFOS, 6:2 Cl-PFESA, and FBG levels. Subgroup analyses revealed that seafood consumption significantly mitigated the associations between PFASs burdens and prediabetes/diabetes. These findings suggest a protective role of dietary seafood against the adverse effects of PFASs exposure on glycemic disorders, offering insights for dietary interventions aimed at mitigating diabetes risks associated with PFASs.

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.

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.

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.

Associations between perfluoroalkyl substances and the severity of non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) has become the leading cause of chronic liver disease worldwide and the determinants driving its severity remain to be elucidated. Perfluoroalkyl substances (PFAS) are synthetic chemical compounds. They are used in commonplace products and persistent in water, soil and the human body. In vitro and animal studies suggest a pathogenic role for PFAS in metabolic diseases such as NAFLD.

OBJECTIVES

We aimed to evaluate the association between NAFLD severity and serum PFAS concentrations in humans.

METHODS

One hundred biopsy-proven NAFLD patients were included with a well-balanced distribution between the different stages of severity: 25 patients with simple steatosis, 25 with early non-alcoholic steatohepatitis (NASH and F0-F1 fibrosis), 33 with fibrotic NASH (NASH and F2-F3 fibrosis), and 17 with cirrhotic NASH (NASH and F4 fibrosis). Liver histological features were evaluated according to the NASH Clinical Research Network classification. Seventeen PFAS were measured by high-performance liquid chromatography coupled with tandem mass spectrometry on serum samples stored at -80 °C.

RESULTS

The median age was 60 years, 61 % of patients were male, 46 % had diabetes and the median body mass index (BMI) was 32 kg/m2. Long-chain PFAS were associated with steatosis grade (p = 0.03). Among the nine PFAS detected in > 50 % of the patients, Perfluoro-n-heptanoic acid (PFHpA) showed significantly higher concentrations in grade 3 steatosis versus grade 1 (p = 0.02). Perfluoro-n-dodecanoic acid (PFDoA) concentrations were higher in patients with significant fibrosis (p = 0.04) and PFHpA in patients with advanced fibrosis (p = 0.02). The association between PFHpA and steatosis grade remained significant in multivariate analysis adjusted for age, gender, BMI, diabetes presence and dyslipidemia (p = 0.004).

DISCUSSION

Our study showed a significant association between PFHpA and liver steatosis in NAFLD. According to data available in the literature, PFHpA could be implicated in liver steatosis through β-oxidation and biosynthesis of fatty acids.

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.

Critical Overview on Endocrine Disruptors in Diabetes Mellitus

Diabetes mellitus is a major public health problem in all countries due to its high human and economic burden. Major metabolic alterations are associated with the chronic hyperglycemia that characterizes diabetes and causes devastating complications, including retinopathy, kidney failure, coronary disease and increased cardiovascular mortality. The most common form is type 2 diabetes (T2D) accounting for 90 to 95% of the cases. These chronic metabolic disorders are heterogeneous to which genetic factors contribute, but so do prenatal and postnatal life environmental factors including a sedentary lifestyle, overweight, and obesity. However, these classical risk factors alone cannot explain the rapid evolution of the prevalence of T2D and the high prevalence of type 1 diabetes in particular areas. Among environmental factors, we are in fact exposed to a growing amount of chemical molecules produced by our industries or by our way of life. In this narrative review, we aim to give a critical overview of the role of these pollutants that can interfere with our endocrine system, the so-called endocrine-disrupting chemicals (EDCs), in the pathophysiology of diabetes and metabolic disorders.

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.

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.

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 (ptrend = 0.001), 1.58 (1.13, 2.21) for PFHxS (ptrend = 0.003), 1.36 (0.97, 1.90) for Sm-PFOS (ptrend = 0.05), 1.85 (1.28, 2.67) for MeFOSAA (ptrend = 0.0004) and 1.64 (1.17, 2.31) for the sum of four common PFAS (n-PFOA, PFNA, PFHxS and total PFOS) (ptrend = 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.

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.