Serum levels of perfluoroalkyl substances (PFAS) and body composition - A cross-sectional study in a middle-aged population

Per- and polyfluoroalkyl substances (PFAS) in senior care facilities and older adult residents

Per- and polyfluoroalkyl substances (PFAS) are fluorinated organic compounds used in a variety of consumer products and industrial applications that persist in the environment, bioaccumulate in biological tissues, and can have adverse effects on human health, especially in vulnerable populations. In this study, we focused on PFAS exposures in residents of senior care facilities. To investigate relationships between indoor, personal, and internal PFAS exposures, we analyzed 19 PFAS in matched samples of dust collected from the residents' bedrooms, and wristbands and serum collected from the residents. The median ∑PFAS concentrations (the sum of all PFAS detected in the samples) measured in dust, wristbands, and serum were 120 ng/g, 0.05 ng/g, and 4.0 ng/mL, respectively. The most abundant compounds in serum were linear- and branched-perfluorooctane sulfonic acid (L-PFOS and B-PFOS, respectively) at medians of 1.7 ng/mL and 0.83 ng/mL, respectively, followed by the linear perfluorooctanoic acid (L-PFOA) found at a median concentration of 0.59 ng/mL. Overall, these three PFAS comprised 80 % of the serum ∑PFAS concentrations. A similar pattern was observed in dust with L-PFOS and L-PFOA found as the most abundant PFAS (median concentrations of 13 and 7.8 ng/g, respectively), with the overall contribution of 50 % to the ∑PFAS concentration. Only L-PFOA was found in wristbands at a median concentration of 0.02 ng/g. Significant correlations were found between the concentrations of several PFAS in dust and serum, and in dust and wristbands, suggesting that the indoor environment could be a significant contributor to the personal and internal PFAS exposures in seniors. Our findings demonstrate that residents of assisted living facilities are widely exposed to PFAS, with several PFAS found in blood of each study participant and in the assisted living environment.

Per- and polyfluoroalkyl substances and cardiometabolic diseases: A review

Per- and polyfluoroalkyl substances (PFAS) are a group of persistent and widespread environmental pollutants that represent a high concern for human health. They have been shown to be associated with several important physiological processes such as lipid metabolism and the immune system. Consequently, PFAS are suspected to play a role in cardiometabolic disease development. However, the evidence regarding associations between PFAS and overt cardiovascular disease and type 2 diabetes remains limited and inconsistent. To address this, we conducted a review of the epidemiological evidence. A deeper understanding of potential underlying molecular mechanisms may help to explain inconsistencies in epidemiological findings. Thus, to gain more mechanistic insight, we also summarized evidence from omics and laboratory studies into an adverse outcome pathway framework. Our observations indicate the potential for associations of PFAS with multiple molecular pathways that could have opposite associations with disease risk, which could be further modified by mixture composition, lifestyle factors or genetic polymorphisms. This identifies the need for exposome studies considering mixture effects, the use of multi-omics data to gain insight in relevant pathways and the integration of epidemiological and laboratory studies to enhance mechanistic understanding and causal inference. Improved comprehension is essential for environmental health risk assessments.

Method Validation for Quantification of PFOS and PFOA in Human Plasma and a Pilot Study in Blood Donors from Thai Red Cross Society

Information regarding per- and polyfluorinated substances concentrations in biological samples from the Thai population was still lacking. A sensitive bioanalytical method was developed and validated for the quantification of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) levels in human plasma. Simple protein precipitation and LC-MS/MS techniques were used with stable isotope internal standards of 13C8-PFOS and 13C8-PFOA. The validated method followed the ICH bioanalytical validation guideline, and the results showed good accuracy, precision, and reproducibility. The validated analytical method was then applied to determine PFOS and PFOA concentrations in 50 human plasma samples from the National Blood Center, Thai Red Cross Society. The concentrations were found to be in ranges of <0.91-6.27 ng/mL for PFOS and <0.49-2.72 ng/mL for PFOA. PFOS was also measured separately for its isomers, and the geometric means of the linear isomer (L-PFOS) and branched isomer (br-PFOS) in plasma samples were at 1.85 and 0.41 ng/mL, respectively. Both PFOS and PFOA concentrations were lower in comparison to previous reports from other countries. The present study showed the application of our reliable method to determine PFOS and PFOA in biological samples in order to monitor the human exposure of both chemicals in Thailand.

The Influence of Adiposity Levels on the Relation between Perfluoroalkyl Substances and High Depressive Symptom Scores in Czech Adults

The extensive use and bioaccumulation of Perfluoroalkyl Substances (PFAS) over time raise concerns about their impact on health, including mental issues such as depression. This study aims to evaluate the association between PFAS and depression. In addition, considering the importance of PFAS as an endocrine disruptor and in adipogenesis, the analyses will also be stratified by body fat status. A cross-sectional study with 479 subjects (56.4% women, 25-89 years) was conducted. Four PFAS were measured: perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluorooctane sulfonate (PFOS). The Poisson regression model was applied using robust error variances. The fully adjusted model included age, sex, educational level, income, smoking, physical activity, body fat percentage, and the questionnaire to assess depression. The prevalence of depression and high body fat was 7.9% and 41.1%, respectively. Only PFOA was significantly associated with depression in the entire sample (prevalence rate (PR): 1.91; confidence interval (CI95%): 1.01-3.65). However, in the group with normal adiposity, PFOA (3.20, CI95%: 1.46-7.01), PFNA (2.54, CI95%: 1.29-5.00), and PFDA (2.09, CI95%: 1.09-4.00) were also significant. Future research should investigate the role of obesity as well as the biological plausibility and possible mechanisms increasing the limited number of evidences between PFAS and depression.

Associations between per- and polyfluoroalkyl substances (PFAS) and diabetes in two population-based cohort studies from Sweden

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) have been suggested to contribute to the development of metabolic diseases such as obesity, diabetes and non-alcoholic fatty liver disease (NAFLD). However, evidence from epidemiological studies remain divergent. The aim of the present study was to evaluate associations between PFAS exposure and prevalent diabetes in a cross-sectional analysis and fasting glucose in a longitudinal analysis.

METHODS

In 2373 subjects aged 45-75 years from the EpiHealth study, three PFAS; perfluorohexanesulfonic acid (PFHxS), perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) were analyzed in plasma together with information on prevalent diabetes. Participants in the PIVUS study (n = 1016 at baseline, all aged 70 years) were followed over 10 years regarding changes in plasma levels of six PFAS; PFHxS, PFOA, PFOS, perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA), and changes in plasma levels of fasting glucose.

RESULTS

In the EpiHealth study, no overall associations could be observed between the levels of PFOA, PFOS or PFHxS and prevalent diabetes. However, there was a significant sex-interaction for PFOA (p = 0.02), and an inverse association could be seen between PFOA (on a SD-scale) and prevalent diabetes in women only (OR: 0.71, 95% CI: 0.52, 0.96, p-value: 0.02). This association showed a non-monotonic dose-response curve. In the PIVUS study, inverse relationships could be observed between the changes in levels (ln-transformed) of PFOA and PFUnDA vs the change in fasting glucose levels (ln-transformed) over 10 years (p = 0.04 and p = 0.02, respectively). As in EpiHealth, these inverse associations were significant only in women (PFOA: β: -0.03, p = 0.02, PFUnDA: β: -0.03, p = 0.03).

IMPACT

Exposure to per- and polyfluoroalkyl substances (PFAS) has been linked to unfavorable human health, including metabolic disorders such as obesity, diabetes and non-alcoholic fatty liver disease. However, results from in vivo, in vitro and epidemiological studies are incoherent. The aim of the present study was therefore to investigate associations between PFAS and diabetes in a cross-sectional study and glucose levels in a longitudinal study. Results show inverse associations in women only. Results also display non-monotonic dose response curves (i.e., that only low levels of PFOA are related to higher probability of prevalent diabetes). This suggests that sex differences and complex molecular mechanisms may underlie the observed findings. A better understanding of the factors and molecular mechanisms contributing to such differences is recognized as an important direction for future research.

CONCLUSIONS

PFOA was found to be inversely related to both prevalent diabetes and changes in plasma glucose levels among women only. Thus, our findings suggest there are sex differences in the inverse relationship of PFOA and type 2 diabetes and glucose levels.

Perfluorodecanoic acid promotes high-fat diet-triggered adiposity and hepatic lipid accumulation by modulating the NLRP3/caspase-1 pathway in male C57BL/6J mice

Perfluorodecanoic acid (PFDA), a chemical contaminant, may casue became obesity, which makes it a public health concern. In this study, we investigated the effects of PFDA on adiposity development and hepatic lipid accumulation in mice fed with a high-fat diet (HFD). Animals were assigned to two diet treatments (low-fat and high-fat); and PFDA was administered through drinking water for 12 weeks. The contaminant promoted body weight gain and adiposity in HFD-fed mice. Moreover, HFD-fed mice exposed to PFDA had impaired glucose metabolism, inflammation and hepatic lipid accumulation compared to mice fed HFD alone. PFDA activated the expression of hepatic NLRP3 and caspase-1, and induced that of SREBP-1c expression in the liver of HFD-fed mice. PFDA exposure in HFD-fed mice significantly inhibited hepatic AMPK expression than animals fed HFD without PFDA exposure. Furthermore, MCC950, an NLRP3 inhibitor, suppressed the upregulation of NLRP3 and caspase-1 expression, and inhibited the expression of SREBP-1c and the accumulation of hepatic lipid in mice exposed to PFDA. Thus, PFDA may enhance HFD-induced adiposity and hepatic lipid accumulation through the NLRP3/caspase-1 pathway. This contaminant may be a key risk factor for obesity development in individuals consuming high-fat foods, particularly Western diet.

Factors affecting serum PFAS concentrations among US females with surgically and naturally induced menopause: data from NHANES 2003-2018

Sex hormones influence excretion of the biopersistent per-and polyfluoroalkyl substances (PFAS) in rodents, but such influences in human studies are less clear. Data from National Health and Nutrition Examination Survey (NHANES) for 2003-2018 for US females aged ≥ 20 years who reported having hysterectomy (HYST, N=1064) and who reported being in natural menopause (MENOP, N=1505) were analyzed for associations of ever use of birth control pills, past pregnancies, live births, and other factors with serum concentrations of six per- and polyfluoroalkyl substances (PFAS). For both HYST and MENOP, PFAS concentrations computed as adjusted geometric means (AGM) were higher among those who took female replacement hormone therapy (HRT) compared to nonusers in multivariable adjusted models, for example PFOS in HRT takers (10.70 ng/mL; 95% C.I. 9.46-12.11) vs. 8.70 ng/mL (95% C.I. 8.07-9.37) in nonusers (p<0.01), and PFOA in HRT users was 2.85 ng/mL (95% C.I. 2.53-3.21) vs. 2.44 ng/mL (95% C.I. 2.32-2.36) in nonusers (p=0.01), with similar findings across race/ethnicity stratifications. HYST participants with retained ovaries sometimes had higher serum PFAS than those without ovaries in post-HYST participants not taking HRT, but results had overlapping confidence intervals in all cases and were inconsistent. PFASs were inversely associated with obesity and directly associated with higher SES as reflected in poverty income ratio (PIR) in most cases, yet HRT results for the entire population are robust to adjustments for obesity and PIR. The results suggest the hypothesis that exogenous hormone use, and specifically estrogen hormones, are associated with higher serum PFAS in postmenopausal women. We discuss potential explanations for the findings, including data from other populations that estrogens may delay the onset of kidney disease, a finding which might paradoxically increase serum PFAS among the HRT population to explain some or all of our findings in a menopausal population.

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.

Per- and polyfluoroalkyl substances exposure and bone mineral density in the U.S. population from NHANES 2005-2014

BACKGROUND

Environmental exposures such as perfluoroalkyl substances (PFASs) were considered potential risks for bone mineral density (BMD).

OBJECTIVE

To examine the associations between PFASs and BMD among the U.S. population.

METHODS

This study included a total of 6416 participants from the National Health and Nutrition Examination Survey (NHANES 2005-2014). Multiple linear regression models were used to analyze the associations between serum PFASs and BMD and the coefficient β with 95% confidence intervals (95% CI) was calculated as the effect estimate. Covariates such as age, race, BMI, smoking, alcohol intake, milk intake, and physical activity were adjusted in these models. Additionally, gender and menopausal period were considered in further subgroup analyses.

RESULTS

Based on the combined data of NHANES 2005-2014, the effects from exposure to PFASs on BMD were found with gender and menopausal status differences. Positive associations were found in PFOA (β = 0.010; 95% CI: 0.003, 0.016), PFHxS (β = 0.007; 95% CI: 0.003, 0.012), and PFNA (β = 0.001; 95% CI: 0.001, 0.017) in total population. Negative associations for PFOA (β = -0.020; 95% CI: -0.029, -0.012), PFOS (β = -0.011; 95% CI: -0.028, -0.011), PFHxS (β = -0.019; 95% CI: -0.025, -0.013), PFDE (β = -0.010; 95% CI: -0.016, -0.005), and PFNA (β = -0.011; 95% CI: -0.021, -0.002) were found in women, while no significant association was found in men. In further subgroup analyses, women in pre-menopause status showed consistent negative associations.

SIGNIFICANCE

PFASs exposure may be associated with BMD and gender and menopausal status confound the associations.

Perfluorodecanoic acid promotes adipogenesis via NLRP3 inflammasome-mediated pathway in HepG2 and 3T3-L1 cells

Perfluorodecanoic acid (PFDA) is a toxic persistent pollutant that is extensively used in food applications, such as food packaging and cookware. Emerging evidence indicates that PFDA exposure were associated with higher plasma triglyceride concentration in human. In contrast, it is unknown how PFDA might affect adipogenesis. To explore the effects and underlying mechanisms of PFDA on lipid metabolism in this study, both HepG2 cells and 3T3-L1 differentiation model were used. The results showed that PFDA promoted the cellular triglyceride accumulation and triglyceride content in concentration-dependent manners. Furthermore, PFDA activated the NLRP3 inflammasome, which is crucial for the induction of lipogenic genes expression including fatty acid synthase (FAS), hydroxymethylglutaryl coenzyme A synthase (HMGCS), and stearoyl-CoA desaturase 1 (SCD1). Additionally, PFDA-induced adipogenesis was abolished by caspase-1 inhibitor and siNLRP3 in HepG2 cells. Moreover, after PFDA treatment, the expression of SREBP1, an important regulator of lipid metabolism, was increased, as well as its target genes, and PFDA-induced SREBP1 enhanced expression can be abolished by caspase-1 inhibitor and siNLRP3 as well. Together, these results provide to understanding of the potential health implications of exposure to PFDA on lipid accumulation, and suggest that PFDA can promote adipogenesis via an NLRP3 inflammasome-mediated SREBP1 pathway.

Reduced Birth Weight and Exposure to Per- and Polyfluoroalkyl Substances: A Review of Possible Underlying Mechanisms Using the AOP-HelpFinder

Prenatal exposure to per- and polyfluorinated substances (PFAS) may impair fetal growth. Our knowledge of the underlying mechanisms is incomplete. We used the Adverse Outcome Pathway (AOP)-helpFinder tool to search PubMed for studies published until March 2021 that examined PFAS exposure in relation to birth weight, oxidative stress, hormones/hormone receptors, or growth signaling pathways. Of these 1880 articles, 106 experimental studies remained after abstract screening. One clear finding is that PFAS are associated with oxidative stress in in vivo animal studies and in vitro studies. It appears that PFAS-induced reactive-oxygen species (ROS) generation triggers increased peroxisome proliferator-activated receptor (PPAR)γ expression and activation of growth signaling pathways, leading to hyperdifferentiation of pre-adipocytes. Fewer proliferating pre-adipocytes result in lower adipose tissue weight and in this way may reduce birth weight. PFAS may also impair fetal growth through endocrine effects. Estrogenic effects have been noted in in vivo and in vitro studies. Overall, data suggest thyroid-damaging effects of PFAS affecting thyroid hormones, thyroid hormone gene expression, and histology that are associated in animal studies with decreased body and organ weight. The effects of PFAS on the complex relationships between oxidative stress, endocrine system function, adipogenesis, and fetal growth should be further explored.