Activation of mouse and human peroxisome proliferator-activated receptor-alpha (PPARα) by perfluoroalkyl acids (PFAAs): Further investigation of C4–C12 compounds

Exposure of women undergoing in-vitro fertilization to per-and polyfluoroalkyl substances: Evidence on negative effects on fertilization and high-quality embryos

In April 2023, the World Health Organization (WHO) reported that 17.5% of the global adult population experience infertility. What may be the contribution of per-and polyfluoroalkyl (PFAS) to this global public health problem? This study explored the associations between in vitro fertilization (IVF) outcomes and plasma concentrations of individual PFAS and PFAS mixtures in women undergoing in vitro fertilization and embryo transfer (IVF-ET) and how these exposures might affect IVF outcomes. We analyzed 8 PFASs in plasma samples from women (N = 259) who underwent IVF treatment. In multivariable generalized linear mixed models, there were statistically significant associations of higher plasma concentrations of PFNA with reduced numbers of total retrieved oocytes [12.486 (95%CI: 0.446,25.418), p trend = 0.017], 2 PN zygotes [6.467(95%CI: 2.034,14.968), p trend = 0.007], and cleavage embryos [6.039(95%CI: 2.162,14.240), p trend = 0.008]. Similarly, there was a continuous decline in the numbers of retrieved 2 PN zygotes and cleavage embryos with increasing concentration of PFOS [6.467(95%CI: 2.034,14.968), p trend = 0.009 and 6.039(95%CI: 2.162,14.240), p trend = 0.031,respectively] and a negative association between PFHxS concentrations and clinical pregnancy during the initial cycles of frozen ET [0.525(95%CI:0.410,0.640), p trend = 0.021]. To investigate the joint effect of PFAS mixtures, a confounder-adjusted BKMR model analysis showed inverse relationship between PFAS mixtures and the number of high-quality embryos, 2 PN zygotes and cleavage embryos, to which the greatest contributors to the mixture effect are PFDeA and PFBS, respectively. It demonstrated that PFAS exposure might exert negative effects on oocyte yield, fertilization and high-quality embryo in women undergoing IVF. These findings suggest that exposure to PFAS may increase the risk of female infertility and further studies are needed to uncover the potential mechanisms underlying the reproductive effects associated with PFAS.

Sex and obesity influence the relationship between perfluoroalkyl substances and lean body mass: NHANES 2011-2018

Objective

Polyfluoroalkyl substances (PFAS) are known endocrine disruptors, that have been the subject of limited research regarding their impact on human lean body mass. The aim of this study was to investigate the effects of PFAS exposure on lean body mass.

Methods

We performed a cross-sectional data analysis involving 1022 adolescents and 3274 adults from the National Health and Nutrition Examination Survey (NHANES) 2011-2018, whose lean body mass was measured by dual-energy X-ray absorptiometry. The lean mass index (LMI) was calculated as lean body mass dividing by the square of height. The association between PFAS and LMI was examined through a multivariate-adjusted weighted generalized linear model. Moreover, weighted quantile sum (WQS) regression models were employed to futher examine the relationship between the mixture of PFAS and LMI.

Results

Regression analyses revealed an inverse correlation between PFAS exposure and LMI after adjusting for potential covariates. Adults with higher serum PFAS concentrations manifested a reduction in whole LMI ( β  = -0.193, 95 % confidence interval (CI): -0.325 to -0.06). Notably, this correlation was particularly significant in adult females and individuals with obesity, and it was observed across diverse anatomical regions, including lower limbs, right arm, trunk, and whole lean body mass. In adult females, the association between PFAS and whole LMI was statistically significant ( β  = -0.294, 95 % CI: -0.495 to -0.094), and a similar trend was found in obese individuals ( β  = -0.512, 95 % CI: -0.762 to -0.261). WQS regression analyses supported the results obtained from weighted linear regression analyses.

Conclusions

Our study suggests that exposure to PFAS, whether individually or in combination, is associated with decreased lean body mass in specific body areas, with sex and obesity serving as major influencing factors.

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.

PFHpA alters lipid metabolism and increases the risk of metabolic dysfunction-associated steatotic liver disease in youth-a translational research framework

To address the growing epidemic of liver disease, particularly in pediatric populations, it is crucial to identify modifiable risk factors for the development and progression of metabolic dysfunction-associated steatotic liver disease (MASLD). Per- and polyfluoroalkyl substances (PFAS) are persistent ubiquitous chemicals and have emerged as potential risk factors for liver damage. However, their impact on the etiology and severity of MASLD remains largely unexplored in humans. This study aims to bridge the gap between human and in vitro studies to understand how exposure to perfluoroheptanoic acid (PFHpA), one of the emerging PFAS replacements which accumulates in high concentrations in the liver, contributes to MASLD risk and progression. First, we showed that PFHpA plasma concentrations were significantly associated with increased risk of MASLD in obese adolescents. Further, we examined the impact of PFHpA on hepatic metabolism using 3D human liver spheroids and single-cell transcriptomics to identify major hepatic pathways affected by PFHpA. Next, we integrated the in vivo and in vitro multi-omics datasets with a novel statistical approach which identified signatures of proteins and metabolites associated with MASLD development triggered by PFHpA exposure. In addition to characterizing the contribution of PFHpA to MASLD progression, our study provides a novel strategy to identify individuals at high risk of PFHpA-induced MASLD and develop early intervention strategies. Notably, our analysis revealed that the proteomic signature exhibited a stronger correlation between both PFHpA exposure and MASLD risk compared to the metabolomic signature. While establishing a clear connection between PFHpA exposure and MASLD progression in humans, our study delved into the molecular mechanisms through which PFHpA disrupts liver metabolism. Our in vitro findings revealed that PFHpA primarily impacts lipid metabolism, leading to a notable increase of lipid accumulation in human hepatocytes after PFHpA exposure. Among the pathways involved in lipid metabolism in hepatocytes, regulation of lipid metabolism by PPAR-a showed a remarkable activation. Moreover, the translational research framework we developed by integrating human and in vitro data provided us biomarkers to identify individuals at a high risk of MASLD due to PFHpA exposure. Our framework can inform policies on PFAS-induced liver disease and identify potential targets for prevention and treatment strategies.

Metabolic, neurotoxic and immunotoxic effects of PFAAs and their mixtures on the proteome of the head kidney and plasma from rainbow trout (Oncorhynchus mykiss)

PFAAs (Perfluoroalkyl acids) are a class of bioaccumulative, persistent and ubiquitous environmental contaminants which primarily occupy the hydrosphere and its sediments. Currently, a paucity of toxicological information exists for short chain PFAAs and complex mixtures. In order to address these knowledge gaps, we performed a 3-week, aqueous exposure of rainbow trout to 3 different concentrations of a PFAA mixture (50, 100 and 500 ng/L) modeled after the composition determined in Lake Ontario. We conducted an additional set of exposures to individual PFAAs (25 nM each of PFOS (12,500 ng/L), PFOA (10,300 ng/L), PFBS (7500 ng/L) or PFBA (5300 ng/L) to evaluate differences in biological response across PFAA congeners. Untargeted proteomics and phosphorylated metabolomics were conducted on the blood plasma and head kidney tissue to evaluate biological response. Plasma proteomic responses to the mixtures revealed several unexpected outcomes including Similar proteomic profiles and biological processes as the PFOS exposure regime while being orders of magnitude lower in concentration and an atypical dose response in terms of the number of significantly altered proteins (FDR < 0.1). Biological pathway analysis revealed the low mixture, medium mixture and PFOS to significantly alter (FDR < 0.05) a number of processes including those involved in lipid metabolism, oxidative stress and the nervous system. We implicate plasma increases in PPARD and PPARG as being directly related to these biological processes as they are known to be important regulators in all 3 processes. In contrast to the blood plasma, the high mixture and PFOA exposure regimes caused the greatest change to the head kidney proteome, altering many proteins being involved in lipid metabolism, oxidative stress and inflammation. Our findings support the pleiotropic effect PFAAs have on aquatic organisms at environmentally relevant doses including those on PPAR signaling, metabolic dysregulation, immunotoxicity and neurotoxicity.

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

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

Maternal PFOS exposure affects offspring development in Nrf2-dependent and independent ways in zebrafish (Danio rerio)

Perfluorooctanesulfonic acid (PFOS) is a ubiquitous legacy environmental contaminant detected broadly in human samples and water supplies. PFOS can cross the placenta and has been detected in cord blood and breastmilk samples, underscoring the importance of understanding the impacts of maternal PFOS exposure during early development. This study aimed to investigate the effects of a preconception exposure to PFOS on developmental endpoints in offspring, as well as examine the role of the transcription factor Nuclear factor erythroid-2-related factor (Nrf2a) in mediating these effects. This transcription factor regulates the expression of several genes that protect cells against oxidative stress including during embryonic development. Adult female zebrafish were exposed to 0.02, 0.08 or 0.14 mg/L PFOS for 1 week (duration of one cycle of oocyte maturation) and then paired with unexposed males from Nrf2a mutant or wildtype strains. Embryos were collected for two weeks or until completion of 5 breeding events. PFOS was maternally transferred to offspring independent of genotype throughout all breeding events in a dose-dependent manner, ranging from 2.77 to 23.72 ng/embryo in Nrf2a wildtype and 2.40 to 15.80 ng/embryo in Nrf2a mutants. Although embryo viability at collection was not impacted by maternal PFOS exposure, developmental effects related to nutrient uptake, growth and pancreatic β-cell morphology were observed and differed based on genotype. Triglyceride levels were increased in Nrf2a wildtype eggs from the highest PFOS group. In Nrf2a wildtype larvae there was a decrease in yolk sac uptake while in Nrf2a mutants there was an increase. Additionally, there was a significant decrease in pancreatic β-cell (islet) area in wildtype larvae from the 0.14 mg/L PFOS accompanied by an increase in the prevalence of abnormal islet morphologies compared to controls. Abnormal morphology was also observed in the 0.02 and 0.08 mg/L PFOS groups. Interestingly, in Nrf2a mutants there was a significant increase in the pancreatic β-cell area in the 0.02 and 0.08 mg/L PFOS groups and no changes in the prevalence of abnormal islet morphologies. These results suggest that the regulation of processes like nutrient consumption, growth and pancreatic β-cell development are at least partially modulated by the presence of a functional Nrf2a transcriptomic response. Overall, preconception exposure to environmental pollutants, such as PFOS, may impact the maturing oocyte and cause subtle changes that can ultimately impact offspring health and development.

Effects of developmental exposure to individual and combined PFAS on development and behavioral stress responses in larval zebrafish

Per- and polyfluoroalkyl substances (PFAS) are a class of synthetic chemicals known for their widespread use and persistence in the environment. Laboratory and epidemiological studies investigating these compounds have signaled their neurotoxic and endocrine-disrupting propensities, prompting further research into their effects on behavioral stress responses and their potential role as risk factors for stress-related disorders such as anxiety and depression. This study elucidates the ramifications of early developmental exposures to individual and combined PFAS on the development and behavioral stress responses of larval zebrafish (Danio rerio), an established model in toxicological research. Wild-type zebrafish embryos were enzymatically dechorionated and exposed to PFOS, PFOA, PFHxS, and PFHxA between 6 and 120 h post-fertilization (hpf). We targeted environmentally relevant concentrations stemming from the USEPA 2016 Hazard Advisory Limit (HAL, 0.07 μg/L) and folds higher (0.35, 0.7, 1.75, and 3.5 μg/L). Evaluations at 120 hpf encompassed mortality, overall development, developmental defects, and larval activity both at baseline stress levels and following exposure to acute stressors (acoustic and visual). Larval exposure to PFOA, PFOS, or PFHxS (0.07 μg/L or higher) elicited significant increases in mortality rates, which capped at 23.1%. Exposure to individual chemicals resulted in limited effects on overall development but increased the prevalence of developmental defects in the body axis, swim bladder, pigmentation, and eyes, as well as the prevalence of yolk sac and pericardial edemas. Larval activity at baseline stress levels and following exposure to acute stimuli was significantly altered. Combined exposure to all four chemicals intensified the breadth of developmental and behavioral alterations, suggesting possible additive or synergistic effects. Our findings shed light on the developmental and neurobehavioral disturbances associated with developmental exposure to PFAS at environmentally relevant concentrations, the added risks of combined exposures to these chemicals, and their possible role as environmental risk factors for stress-related disorders.

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.

Associations of dietary intake and longitudinal measures of per- and polyfluoroalkyl substances (PFAS) in predominantly Hispanic young Adults: A multicohort study

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are pollutants linked to adverse health effects. Diet is an important source of PFAS exposure, yet it is unknown how diet impacts longitudinal PFAS levels.

OBJECTIVE

To determine if dietary intake and food sources were associated with changes in blood PFAS concentrations among Hispanic young adults at risk of metabolic diseases.

METHODS

Predominantly Hispanic young adults from the Children's Health Study who underwent two visits (CHS; n = 123) and young adults from NHANES 2013-2018 who underwent one visit (n = 604) were included. Dietary data at baseline was collected using two 24-hour dietary recalls to measure individual foods and where foods were prepared/consumed (home/restaurant/fast-food). PFAS were measured in blood at both visits in CHS and cross-sectionally in NHANES. In CHS, multiple linear regression assessed associations of baseline diet with longitudinal PFAS; in NHANES, linear regression was used.

RESULTS

In CHS, all PFAS except PFDA decreased across visits (all p < 0.05). In CHS, A 1-serving higher tea intake was associated with 24.8 %, 16.17 %, and 12.6 % higher PFHxS, PFHpS, and PFNA at follow-up, respectively (all p < 0.05). A 1-serving higher pork intake was associated with 13.4 % higher PFOA at follow-up (p < 0.05). Associations were similar in NHANES, including unsweetened tea, hot dogs, and processed meats. For food sources, in CHS each 200-gram increase in home-prepared food was associated with 0.90 % and 1.6 % lower PFOS at baseline and follow-up, respectively, and in NHANES was associated with 0.9 % lower PFDA (all p < 0.05).

CONCLUSION

Results suggest that beverage consumption habits and food preparation are associated with differences in PFAS levels in young adults. This highlights the importance of diet in determining PFAS exposure and the necessity of public monitoring of foods and beverages for PFAS contamination.

Prenatal exposure to per- and polyfluoroalkyl substances and early childhood adiposity and cardiometabolic health in the Healthy Start study

BACKGROUND/OBJECTIVES

Observational and experimental studies have suggested that prenatal exposure to per- and polyfluoroalkyl substances (PFAS) can increase childhood adiposity and cardiometabolic disruption. However, most previous studies have used weight-based measures that cannot distinguish between fat mass and lean mass. We evaluated associations of prenatal PFAS exposure with precisely measured body composition and cardiometabolic biomarkers in early childhood.

SUBJECTS

373 eligible mother-infant pairs in the Healthy Start longitudinal cohort.

METHODS

We used multiple linear regression and Bayesian kernel machine regression models to estimate associations between five PFAS in maternal mid-pregnancy serum, and early childhood adiposity via air displacement plethysmography. Secondary outcomes included body mass index, waist circumference, and fasting serum lipids, glucose, insulin and adipokines. Models were adjusted for potential confounders and effect modification by child sex was evaluated.

RESULTS

The median age of children at assessment was 4.6 years. Prenatal concentration of perfluorooctanoate (PFOA) was positively associated with percent fat mass (0.89% per log2-unit increase, 95% CI: 0.15, 1.64), while perfluorononanoate (PFNA) was positively associated with fat mass index and body mass index. Cardiometabolic markers in blood were generally not associated with prenatal PFAS in this population. Mixture models confirmed the importance of PFNA and PFOA in predicting percent fat mass, while PFNA was most important for fat mass index, body mass index, and waist circumference. There were no significant effects of the five PFAS as a mixture, potentially due to opposing effects of different PFAS.

CONCLUSIONS

Our results agree with previous studies showing that prenatal serum concentrations of certain PFAS are positively associated with early childhood adiposity. Notably, associations were stronger for measures incorporating precisely measured fat mass compared to measures of body size or weight. Early life increases in adiposity may precede the development of adverse cardiometabolic health outcomes in children exposed to PFAS during gestation.

Concentrations and association between exposure to mixed perfluoroalkyl and polyfluoroalkyl substances and glycometabolism among adolescents

BACKGROUND

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are widely used for industrial and commercial purposes and have received increasing attention due to their adverse effects on health.

OBJECTIVE

To examine the relationship of serum PFAS and glycometabolism among adolescents based on the US National Health and Nutrition Examination Survey.

METHODS

General linear regression models were applied to estimate the relationship between exposure to single PFAS and glycometabolism. Weighted quantile sum (WQS) regression models and Bayesian kernel machine regressions (BKMR) were used to assess the associations between multiple PFASs mixture exposure and glycometabolism.

RESULTS

A total of 757 adolescents were enrolled. Multivariable regression model showed that Me-PFOSA-AcOH exposure was negatively associated with fasting blood glucose. WQS index showed that there was marginal negative correlation between multiple PFASs joint exposure and the homeostasis model of assessment for insulin resistance index (HOMA-IR) (β = -0.26, p < .068), and PFHxS had the largest weight. BKMR models showed that PFASs mixture exposure were associated with decreased INS and HOMA-IR, and the exposure-response relationship had curvilinear shape.

CONCLUSIONS

The increase in serum PFASs were associated with a decrease in HOMA-IR among adolescents. Mixed exposure models could more accurately and effectively reveal true exposure.Key MessagesThe detection rates of different PFAS contents in adolescent serum remained diverse.Adolescent serum PFASs had negative curvilinear correlation with INS and HOMA-IR levels.PFHxS had the highest weight in the associations between multiple PFASs and adolescent glycometabolism.

Elevated Levels of Ultrashort- and Short-Chain Perfluoroalkyl Acids in US Homes and People

Per- and polyfluoroalkyl substances (PFAS) make up a large group of fluorinated organic compounds extensively used in consumer products and industrial applications. Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), the two perfluoroalkyl acids (PFAAs) with 8 carbons in their structure, have been phased out on a global scale because of their high environmental persistence and toxicity. As a result, shorter-chain PFAAs with less than 8 carbons in their structure are being used as their replacements and are now widely detected in the environment, raising concerns about their effects on human health. In this study, 47 PFAAs and their precursors were measured in paired samples of dust and drinking water collected from residential homes in Indiana, United States, and in blood and urine samples collected from the residents of these homes. Ultrashort- (with 2 or 3 carbons [C2-C3]) and short-chain (with 4-7 carbons [C4-C7]) PFAAs were the most abundant in all four matrices and constituted on average 69-100% of the total PFAA concentrations. Specifically, trifluoroacetic acid (TFA, C2) and perfluoropropanoic acid (PFPrA, C3) were the predominant PFAAs in most of the samples. Significant positive correlations (n = 81; r = 0.23-0.42; p < 0.05) were found between TFA, perfluorobutanoic acid (PFBA, C4), and perfluoroheptanoic acid (PFHpA, C7) concentrations in dust or water and those in serum, suggesting dust ingestion and/or drinking water consumption as important exposure pathways for these compounds. This study demonstrates that ultrashort- and short-chain PFAAs are now abundant in the indoor environment and in humans and warrants further research on potential adverse health effects of these exposures.

Perfluoroundecanoic acid induces DNA damage, reproductive and pathophysiological dysfunctions via oxidative stress in male Swiss mice

Perfluoroundecanoic acid (PFUnA) is an eleven carbon-chain compound that belongs to the perfluoroalkyl carboxylic acid family. It has been detected in the human blood, effluents, and surface/ground waters, but its toxic effects to the DNA and reproductive system remain unclear. This study was aimed at exploring the toxicity of PFUnA on the hepatic DNA, organ-system and reproductive system in orally treated male Swiss mice. In this present study, administration of PFUnA for 28 days with five doses (0.1, 0.3, 05, 0.7 and 1.0 mg kg-1 b.w./d) in male Swiss mice induced significant hepatic DNA damage which was observed using the alkaline comet assay and equally altered hematological and clinical biochemical parameters. In addition to testicular atrophy, sperm count and sperm motility significantly decreased while sperm abnormalities increased after 35 days exposure. Serum LH and FSH levels were remarkably increased while serum testosterone levels were strikingly reduced. Histopathology revealed the liver, kidney, and testis as potential targets of PFUnA toxicity. Increased activities of superoxide dismutase (SOD) and catalase (CAT), as well as levels of glutathione-s-transferase (GST) and reduced glutathione (GSH), with consistent reduction of glutathione peroxidase (GPx) and reduced glutathione (GSH) in the liver and testis induced oxidative stress. In conclusion, PFUnA exhibited both genotoxicity and reproductive toxicity via oxidative stress induction.

Target Exposome for Characterizing Early Gestational Exposure to Contaminants of Emerging Concern and Association with Gestational Diabetes Mellitus

Characterization of gestational exposure to complex contaminants of emerging concern (CECs) is critical to the identification of environmental risk factors for pregnancy complications. However, determination of various CECs with diverse physicochemical properties in biological fluids is technically challenging. In the present study, we developed a target exposome protocol, consisting of simple liquid-liquid extraction-based sample preparation and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, to determine 325 CECs covering 11 subclasses, including poly- and perfluoroalkyl substances, organophosphate esters, ultraviolet (UV) stabilizers, synthetic antioxidants, phthalate esters, and several others. The protocol exhibits exceptional advantages over traditional approaches in the coverage of chemicals, sample volume demand, and time and financial cost. The protocol was applied in a prospective nested gestational diabetes mellitus (GDM) study including 120 cases and 240 matched healthy controls. Thirty-three CECs were detected in >70% of the samples, with a combined concentration of 17.0-484.7 ng/mL. Bayesian kernel machine regression analysis showed that exposure to the CEC mixture was significantly associated with a higher GDM risk. For example, when increasing all CECs in the mixture from 50th percentile to 75th percentile, the estimated probit of GDM incidence had an increase of 92% (95% CI: 56%, 127%). Meanwhile, perfluorohexanesulfonic acid, 1,3-diphenylguanidine, and dibutyl fumarate were identified as the key CECs driving the joint effect. This work demonstrates great potential of our target exposome protocol for environmental risk factor identification in large-scale epidemiology or biomonitoring studies.

The interference between effects of PFAS exposure on thyroid hormone disorders and cholesterol levels: an NHANES analysis

Studies have documented that per- and polyfluoroalkyl substance (PFAS) exposures are associated with thyroid hormones (TH) and lipid levels. This study investigates whether these effects interfere with each other. We analyzed data on 3954 adults in the US National Health and Nutrition Examination Survey (NHANES; 2007-2012). TH disorder was defined using thyroid hormones. Serum high-density lipoprotein (HDL) cholesterol, total cholesterol, and six types of PFAS were included. Weighted quantile sum (WQS) regression was used to estimate the overall effect of PFAS mixture on TH disorder and cholesterols, respectively. Potential confounders, including age, race, gender, education, household poverty, smoking, and alcohol drinking, were adjusted. PFAS mixture was associated increased risk for TH disorder (odds ratio = 1.21, 95% confidence interval (CI): 1.02, 1.43), higher HDL cholesterol (linear coefficient = 1.31, 95% CI: 0.50, 2.11), and higher total cholesterol (linear coefficient = 5.30, 95% CI: 3.40, 7.21). TH disorder was associated with higher HDL cholesterol (linear coefficient = 2.30, 95% CI: 0.50, 2.11), but not total cholesterol. When adjusted for TH disorder, the effect estimates of PFAS mixture remain roughly unchanged on HDL cholesterol (linear coefficient = 1.13, 95% CI: 0.28, 1.98) and total cholesterol (linear coefficient = 5.61, 95% CI: 3.58, 7.63). Sex modified the effect of PFAS mixture on HDL cholesterol (P for interaction: 0.04) but did not change the interaction between PFAS and TH disorder on cholesterols. We corroborated the adverse health effects of PFAS exposure on TH and lipids; however, these two effects appear to be independent of and not interfere with each other.

Cross-Species Transcriptomics Analysis Highlights Conserved Molecular Responses to Per- and Polyfluoroalkyl Substances

In recent decades, per- and polyfluoroalkyl substances (PFASs) have garnered widespread public attention due to their persistence in the environment and detrimental effects on the health of living organisms, spurring the generation of several transcriptome-centered investigations to understand the biological basis of their mechanism. In this study, we collected 2144 publicly available samples from seven distinct animal species to examine the molecular responses to PFAS exposure and to determine if there are conserved responses. Our comparative transcriptional analysis revealed that exposure to PFAS is conserved across different tissues, molecules and species. We identified and reported several genes exhibiting consistent and evolutionarily conserved transcriptional response to PFASs, such as ESR1, HADHA and ID1, as well as several pathways including lipid metabolism, immune response and hormone pathways. This study provides the first evidence that distinct PFAS molecules induce comparable transcriptional changes and affect the same metabolic processes across inter-species borders. Our findings have significant implications for understanding the impact of PFAS exposure on living organisms and the environment. We believe that this study offers a novel perspective on the molecular responses to PFAS exposure and provides a foundation for future research into developing strategies for mitigating the detrimental effects of these substances in the ecosystem.

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.

Estimation of Per- and Polyfluorinated Alkyl Substance Induction Equivalency Factors for Humpback Dolphins by Transactivation Potencies of Peroxisome Proliferator-Activated Receptors

The potential risks of per- and polyfluoroalkyl substance (PFAS) accumulation in nearshore dolphins are not well understood. Here, transcriptional activities of 12 PFAS on peroxisome proliferator-activated receptors (PPAR-α, -β/δ, and -γ) in Indo-Pacific humpback dolphins (Sousa chinensis) were evaluated. All PFAS activated scPPAR-α in a dose-dependent manner. PFHpA exhibited the highest induction equivalency factors (IEFs). The order of IEFs for other PFAS was as follows: PFOA > PFNA > PFHxA > PFPeA > PFHxS > PFBA > PFOS > PFBuS ≈ PFDA ≫ PFUnDA and PFDoDA (not activated). The total induction equivalents (∑IEQs, 5537 ng/g wet weight) indicated that more attention should be paid to investigating contamination levels in dolphins, especially in PFOS (82.8% contribution to the ∑IEQs). The scPPAR-β/δ and -γ were not affected by any PFAS, except for PFOS, PFNA, and PFDA. Furthermore, PFNA and PFDA could induce higher PPAR-β/δ and PPAR-γ-mediated transcriptional activities than PFOA. Compared to human beings, PFAS might be more potent PPAR-α activators in humpback dolphins, suggesting that the dolphins may be more susceptible to the adverse effects of PFAS. Our results may be instructive for understanding the impacts of PFAS on marine mammal health due to the identical PPAR ligand-binding domain.

Effects of perfluorooctanoic acid on endoplasmic reticulum stress and lipid metabolism-related genes in human pancreatic cells

Perfluorooctanoic acid (PFOA) is environmentally persistent and has been classified by The International Cancer Research Agency (IARC) as a possible human pancreatic carcinogen. In this study, the epigenetic alteration, the changes in the expression levels of endoplasmic reticulum stress-related and metabolism-related genes, as well as DNA methyltransferase expression were investigated using RT-PCR and ELISA assays. PFOA induced a significant increase in the methylation ratio (5-mC%), impacted DNA methylation maintenance gene expression and decreased lipid metabolism-related genes except for PPARγ (≥ 13-fold increase). While PFOA induced the expression of ATF4 (≥ 5.41-folds), CHOP (≥ 5.41-folds) genes, it inhibited the expression of ATF6 (≥ 67.2%), GRP78 (≥ 64.3%), Elf2α (≥ 95.8%), IRE1 (≥ 95.5%), and PERK (≥ 91.7%) genes. It is thought that epigenetic mechanisms together with disruption in the glucose-lipid metabolism and changes in endoplasmic reticulum stress-related genes may play a key role in PFOA-induced pancreatic toxicity.

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.

Effect of perfluoroalkyl exposure in pregnancy and infancy on intrauterine and childhood growth and anthropometry. Sub study from COPSAC2010 birth cohort

BACKGROUND

Perfluoroalkyl substances PFOS and PFOA are persistent and bioaccumulative exogenous chemicals in the human body with a range of suspected negative health effects. It is hypothesised that exposure during prenatal and early postnatal life might have particularly detrimental effects on intrauterine and childhood growth. In a Danish longitudinal mother-child cohort we investigate effect of PFOS and PFOA in pregnancy and infancy on intrauterine and childhood growth and anthropometry.

METHODS

COPSAC₂₀₁₀ is an ongoing population based mother-child cohort of 738 pregnant women and their children followed from 24 week gestation with longitudinal deep clinical phenotyping until age 10 years. In this observational cohort sub study plasma PFOS and PFOA concentrations were semi-quantified by untargeted metabolomics in the mothers at week 24 and 1 week postpartum and in the children at ages 6 and 18 months and calibrated using a targeted pipeline. We examined associations to intrauterine and childhood growth and anthropometry, including interactions with child sex. Untargeted and targeted blood metabolomics profiles were integrated to investigate underlying mechanisms.

FINDINGS

Pregnancy plasma PFOA concentrations were associated with lower birth size -0.19 [-0.33; -0.05] BMI z-score per 1-ng/mL and increased childhood height (z-scored) at age 6: 0.18 [0.05; 0.31], but there was no association between childs' own infancy plasma PFOA concentration and height. Pregnancy plasma PFOS concentrations were also associated with lower birth BMI (-0.04 [-0.08; -0.01]), but in childhood pregnancy plasma PFOS concentration interacted with child sex on BMI and fat percentage at 6 years with negative associations in girls and positive in boys. The effect of maternal plasma PFOS concentration on lower girl BMI was borderline mediated through increasing child plasma lactosyl-ceramide levels (p-mediation=0.08). Similarly the effect of maternal plasma PFOS concentration on higher boy fat percentage was borderline mediated through increasing child plasma lactosyl-ceramide levels (p-mediation=0.07). Infancy concentrations of plasma PFOS associated with lower height in childhood, -0.06 z-score at age 6 [-0.19; -0.03].

INTERPRETATION

Higher PFOS and PFOA plasma concentrations during pregnancy had detrimental effects on fetal growth. The effects on childhood growth were not similar as PFOA increased child height, opposite of PFOS in multipollutant models suggesting a differing fetal programming effect. Sex specific growth effects were borderline mediated through an altered lactosyl-ceramide metabolism, proposing a possible mechanism of PFOS that has long-lasting health consequences in this observational study.

FUNDING

All funding received by COPSAC are listed on www.copsac.com. The Lundbeck Foundation (Grant no R16-A1694); The Novo Nordic Foundation (Grant nos NNF20OC0061029, NNF170C0025014, NNF180C0031764) The Ministry of Health (Grant no 903516); Danish Council for Strategic Research (Grant no 0603-00280B) and The Capital Region Research Foundation have provided core support to the COPSAC research center. Effort from JALS is supported by R01HL123915, R01HL141826, and R01HL155742 from NIH/NHLBI. CEW was supported by the Swedish Heart Lung Foundation (HLF 20180290, HLF 20200693). BC has received funding for this project from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. 946228). The funding agencies did not have any role in design and conduct of the study; collection, management, and interpretation of the data; or preparation, review, or approval of the manuscript.

In vitro activity of a panel of per- and polyfluoroalkyl substances (PFAS), fatty acids, and pharmaceuticals in peroxisome proliferator-activated receptor (PPAR) alpha, PPAR gamma, and estrogen receptor assays

Data demonstrate numerous per- and polyfluoroalkyl substances (PFAS) activate peroxisome proliferator-activated receptor alpha (PPARα), however, additional work is needed to characterize PFAS activity on PPAR gamma (PPARγ) and other nuclear receptors. We utilized in vitro assays with either human or rat PPARα or PPARγ ligand binding domains to evaluate 16 PFAS (HFPO-DA, HFPO-DA-AS, NBP2, PFMOAA, PFHxA, PFOA, PFNA, PFDA, PFOS, PFBS, PFHxS, PFOSA, EtPFOSA, and 4:2, 6:2 and 8:2 FTOH), 3 endogenous fatty acids (oleic, linoleic, and octanoic), and 3 pharmaceuticals (WY14643, clofibrate, and the metabolite clofibric acid). We also tested chemicals for human estrogen receptor (hER) transcriptional activation. Nearly all compounds activated both PPARα and PPARγ in both human and rat ligand binding domain assays, except for the FTOH compounds and PFOSA. Receptor activation and relative potencies were evaluated based on effect concentration 20% (EC20), top percent of max fold induction (pmaxtop), and area under the curve (AUC). HFPO-DA and HFPO-DA-AS were the most potent (lowest EC20, highest pmaxtop and AUC) of all PFAS in rat and human PPARα assays, being slightly less potent than oleic and linoleic acid, while NBP2 was the most potent in rat and human PPARγ assays. Only PFHxS, 8:2 and 6:2 FTOH exhibited hER agonism >20% pmax. In vitro measures of human and rat PPARα and PPARγ activity did not correlate with oral doses or serum concentrations of PFAS that induced increases in male rat liver weight from the National Toxicology Program 28-d toxicity studies. Data indicate that both PPARα and PPARγ activation may be molecular initiating events that contribute to the in vivo effects observed for many PFAS.

Changes in plasma levels of per- and polyfluoroalkyl substances (PFAS) are associated with changes in plasma lipids - A longitudinal study over 10 years

BACKGROUND

Associations between per- and polyfluoroalkyl substances (PFAS), mainly PFOS and PFOA, and increased blood lipids have been reported primarily from cross-sectional studies. The aim of the present study was to investigate associations between multiple PFAS and blood lipids in a longitudinal fashion.

METHODS

A total of 864 men and women aged 70 years and free from lipid medication were included from the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study from Uppsala Sweden, 614 and 404 of those were reinvestigated at age 75 and 80. At all three occasions, eight PFAS were measured in plasma using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Total cholesterol, triglycerides, low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) were also measured in plasma at all three occasions. Mixed-effects linear regression models were used to examine the relationship between the changes in PFAS levels and changes in lipid levels.

RESULTS

Changes in plasma levels of six out of the eight investigated PFAS were positively associated with changes in plasma lipids after adjustment for sex, change in body mass index (BMI), smoking, physical activity, statin use (age was the same in all subjects), and correction for multiple testing. For example, changes in perfluorodecanoic acid (PFDA) were positively associated with the changes in total cholesterol (β: 0.23, 95% confidence interval (CI): 0.14 to 0.32), triglycerides (β: 0.08, 95% CI: 0.04-0.12) and HDL-cholesterol (β: 0.08, 95% CI: 0.04-0.11).

CONCLUSION

In this longitudinal study with three measurements over 10 years of both plasma PFAS and lipids, changes in six out of the eight investigated PFAS were positively associated with changes in plasma lipids, giving further support for a role of PFAS exposure in human lipid metabolism.

Immunomodulation and exposure to per- and polyfluoroalkyl substances: an overview of the current evidence from animal and human studies

Per- and polyfluoroalkyl substances (PFAS) have been widely used and represent a class of environmental persistent chemicals. An association of a reduction of vaccination efficacy with PFAS serum levels in humans was used by the European Food Safety Authority as a key effect for PFAS risk assessment. The data support for using this association is reviewed by a critical analysis of the respective human epidemiology and the available animal studies on the immunomodulation of PFAS. Based on an analysis of the available human epidemiology, the overall level of evidence regarding associations between PFAS serum levels and reduced antibody response remains weak. Absence of an association between an increase in clinical infections and PFAS serum levels and the limited understanding of the importance of antibody levels as an isolated data point further support this conclusion. Animal toxicity studies with PFAS focusing on immunomodulation also provide only limited support for immunomodulation as an important endpoint in PFAS toxicity. While immunomodulation is observed after PFAS administration, generally at blood concentrations several orders of magnitude above those seen in environmentally exposed humans, the relevance of these observation is hampered by the high doses required to influence immune endpoints, the limited number of endpoints assessed, and inconsistent results. The limitations of the current database on associations of human PFAS exposures outlined here indicate that more evidence is required to select immunomodulation as a critical endpoint for human PFAS risk assessment.

The relationship between multiple perfluoroalkyl substances and cardiorespiratory fitness in male adolescents

Exposure to perfluoroalkyl substances (PFASs) is associated with a number of adverse health outcomes. However, the relationship between mixed and individual PFAS exposure and cardiorespiratory fitness (CRF) in adolescents remains unclear. We used cross-sectional data from 491 teenagers (aged 13-19 years) from the 2003-2004 National Health and Nutrition Examination Survey (NHANES) and examined the association between mixed PFAS exposure and CRF via weighted quantile sum (WQS) regression. Maximal oxygen consumption (VO2max) was used to evaluate CRF. Multivariate linear regression was performed to investigate the relationship between each PFAS and VO2max as well as the relationship between PFAS exposure and the inflammation parameters and blood lipid content. Mediation analyses were performed to investigate possible explanations of the risk of low CRF due to PFAS exposure. The results showed that for males, mixed PFAS exposure was negatively related to VO2max (beta =  - 0.80, 95% CI: - 1.53 to - 0.10, P = 0.028) and that of the PFASs, perfluorononanoic acid (PFNA) had the greatest influence on VO2max. In the individual PFAS analysis, PFNA was negatively related to VO2max in male adolescents (beta =  - 1.49, 95% CI: - 2.65 to - 0.32, P = 0.013). Additionally, significant relationships among serum PFNA levels and total cholesterol and the white blood cell (WBC) count were found. Mediation analyses revealed that WBC count accounted for 24.18% of the variation between PFNA level and CRF. The present results provide epidemiological evidence that exposure to PFASs, mainly PFNA, is negatively associated with CRF, possibly via alterations in WBC count.

Global performance and trends of research on per- and polyfluoroalkyl substances (PFASs) between 2001 and 2018 using bibliometric analysis

Per- and polyfluoroalkyl substances (PFASs) are widely used in food packaging, non-stick pots, and surfactants. However, their persistence in the environment, hazardous nature, and potential for bioaccumulation and long-range transport have alarmed an increasing number of scholars and research institutions. Although several literature reviews on PFASs research exist, only a few of them have considered bibliometric indices. In this study, 3,373 PFASs-related articles published between 2001 and 2018 were analyzed using a bibliometric analysis method based on the Science Citation Index (SCI) Expanded. The software tools for mapping knowledge domain (MKD) (VOSviewer and Science of Science (Sci2)) were used to analyze the performance of contributors and PFASs research topics, hotspots, and trends. Our results reveal that the number of PFASs-related articles published annually has increased significantly, with most originating from the United States (followed by those from China). The Chinese Academy of Sciences has published the most articles. A comprehensive analysis of title, keywords, and keywords plus showed that PFASs research hotspots include humans, precursors, and detection methods, with the main focuses being environmental science, toxicology, and environmental engineering. The four main research topics of PFASs were identified, and a literature review was carried out for each one. Overall, this study can supply researchers with a deeper understanding of the development of PFASs studies and provide a comprehensive data reference for researchers to further grasp the research direction in this field.

Replacement per- and polyfluoroalkyl substances (PFAS) are potent modulators of lipogenic and drug metabolizing gene expression signatures in primary human hepatocytes

Per- and polyfluoroalkyl substances (PFAS) are a class of environmental toxicants, and some, such as perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), have been associated with hepatic steatosis in rodents and monkeys. It was hypothesized that perfluorosulfonic acids (C4, 6, 8), perfluorocarboxylic acids (C4-14), perfluoro(2-methyl-3-oxahexanoic) acid (HFPO-DA), 1H, 1H, 2H, 2H-perfluorooctanesulfonic acid (6:2 FTS) along with 3 PFOS precursors could induce expression of lipid metabolism genes and lipid deposition in human hepatocytes. Five-donor pooled cryopreserved human hepatocytes were cultured and treated with 0.1% DMSO vehicle or various PFAS (0.25 to 25 μM) in media. After a 48-h treatment, mRNA transcripts related to lipid transport, metabolism, and synthesis were measured using a Quantigene Plex assay. After 72-h treatments, hepatocytes were stained with Nile Red dye to quantify intracellular lipids. Overall, PFAS were transcriptionally active at 25 μM. In this model, lipid accumulation was not observed with C8-C12 treatments. Shorter chain PFAS (C4-C5), 6:2 FTS, and PFOS precursor, metFOSA, induced significant liver lipid accumulation, and gene activation at lower concentrations than legacy PFAS. In summary short chain PFAS and other alternative PFAS were more potent gene inducers, and potential health effects of replacement PFAS should be critically evaluated in humans.

The toxicity of perfluorodecanoic acid is mainly manifested as a deflected immune function

BACKGROUND

Perfluorodecanoic acid (PFDA) is a type of perfluoroalkyl acid (PFAA). PFDA has toxicity similar to dioxin; its effect on the body is not through a single target or a single pathway. However, the mechanism at the global level is still unclear.

METHODS AND RESULTS

We treated mice with PFDA and characterized the global changes in gene expression in the liver using microarray analyses. The enriched KEGG pathways and GO analyses revealed that PFDA greatly affected the immune response, which was different from the response of gastric cells previously studied. As a proof of principle, the expressions of IL-1β and IL-18 were both decreased after PFDA treatment, and qRT-PCR and ELISAs verified the reduction of IL-1β and IL-18 in liver tissues. Mechanistic investigations indicated that PFDA inhibited caspase-1 activation, and decreased the mRNA levels of NLRP1, NLRP3, and NLRC4; thus, suggesting that inflammasome assemblies were suppressed. Further microarray data revealed that cIAP2 and its binding proteins, which are critical for regulating inflammasome assembly, were also repressed by PFDA. In addition, flow cytometry results revealed a significant inhibition of Th1 cell differentiation in the livers of PFDA-treated mice.

CONCLUSIONS

The results of this study suggested that one of the main toxic effects of PFDA on livers was the inhibition of immune response.

Reduced bioaccumulation of fluorotelomer sulfonates and perfluoroalkyl acids in earthworms (Eisenia fetida) from soils amended with modified clays

Soils contaminated by per- and polyfluoroalkyl substances (PFAS) pose long-term sources to adjacent water bodies and soil invertebrates. The study investigated the stabilization using a modified clay adsorbent (FLUORO-SORB100®) in reducing the bioaccumulation of 13 anionic PFAS by earthworms (Eisenia fetida), as compared to coal-based granular activated carbon. The target PFAS included four perfluoroalkyl sulfonates such as perfluorooctane sulfonate (PFOS), six perfluoroalkyl carboxylates (e.g., perfluorooctanoate PFOA), and three (X:2) fluorotelomer sulfonates. Laboratory-spiked surface soil and the soil collected from a site contaminated by aqueous film-forming foams were examined. Both adsorbents resulted in reduced earthworm PFAS body burdens at the end of the 28-day uptake phase. The highest adsorbent amendment concentration (4 w/w%) was most effective, achieving >95% reduction of PFAS body burden. Soil leaching tests indicated better immobilization performance by the clay adsorbent for most analytes; in comparison, the activated carbon performed better at reducing total PFAS body burdens, possibly owing to the avoidance of larger-sized particles by earthworms. Strong positive logarithm relationships were observed between leachate concentrations and earthworm body burdens for most PFAS in the spiked soil. The study demonstrated that stabilization of PFAS using modified clay adsorbents can achieve concurrent benefits of lowering leachability and reducing bioaccumulation.

Predicting the effects of per- and polyfluoroalkyl substance mixtures on peroxisome proliferator-activated receptor alpha activity in vitro

Human exposure to per- and polyfluoroalkyl substances (PFAS) is ubiquitous, with mixtures of PFAS detected in drinking water, food, household dust, and other exposure sources. Animal toxicity studies and human epidemiology indicate that PFAS may act through shared mechanisms including activation of peroxisome proliferator activated receptor α (PPARα). However, the effect of PFAS mixtures on human relevant molecular initiating events remains an important data gap in the PFAS literature. Here, we tested the ability of modeling approaches to predict the effect of diverse PPARα ligands on receptor activity using Cos7 cells transiently transfected with a full length human PPARα (hPPARα) expression construct and a peroxisome proliferator response element-driven luciferase reporter. Cells were treated for 24 h with two full hPPARα agonists (pemafibrate and GW7647), a full and a partial hPPARα agonist (pemafibrate and mono(2-ethylhexyl) phthalate), or a full hPPARα agonist and a competitive antagonist (pemafibrate and GW6471). Receptor activity was modeled with three additive approaches: effect summation, relative potency factors (RPF), and generalized concentration addition (GCA). While RPF and GCA accurately predicted activity for mixtures of full hPPARα agonists, only GCA predicted activity for full and partial hPPARα agonists and a full agonist and antagonist. We then generated concentration response curves for seven PFAS, which were well-fit with three-parameter Hill functions. The four perfluorinated carboxylic acids (PFCA) tended to act as full hPPARα agonists while the three perfluorinated sulfonic acids (PFSA) tended to act as partial agonists that varied in efficacy between 28-67 % of the full agonist, positive control level. GCA and RPF performed equally well at predicting the effects of mixtures with three PFCAs, but only GCA predicted experimental activity with mixtures of PFSAs and a mixture of PFCAs and PFSAs at ratios found in the general population. We conclude that of the three approaches, GCA most accurately models the effect of PFAS mixtures on hPPARα activity in vitro. Understanding the differences in efficacy with which PFAS activate hPPARα is essential for accurately predicting the effects of PFAS mixtures. As PFAS can activate multiple nuclear receptors, future analyses should examine mixtures effects in intact cells where multiple molecular initiating events contribute to proximate effects and functional changes.

Predicting the effects of per- and polyfluoroalkyl substance mixtures on peroxisome proliferator-activated receptor alpha activity in vitro

Human exposure to per- and polyfluoroalkyl substances (PFAS) is ubiquitous, with mixtures of PFAS detected in drinking water, food, household dust, and other exposure sources. Animal toxicity studies and human epidemiology indicate that PFAS may act through shared mechanisms including activation of peroxisome proliferator activated receptor α (PPARα). However, the effect of PFAS mixtures on human relevant molecular initiating events remains an important data gap in the PFAS literature. Here, we tested the ability of modeling approaches to predict the effect of diverse PPARα ligands on receptor activity using Cos7 cells transiently transfected with a full length human PPARα (hPPARα) expression construct and a peroxisome proliferator response element-driven luciferase reporter. Cells were treated for 24 h with two full hPPARα agonists (pemafibrate and GW7647), a full and a partial hPPARα agonist (pemafibrate and mono(2-ethylhexyl) phthalate), or a full hPPARα agonist and a competitive antagonist (pemafibrate and GW6471). Receptor activity was modeled with three additive approaches: effect summation, relative potency factors (RPF), and generalized concentration addition (GCA). While RPF and GCA accurately predicted activity for mixtures of full hPPARα agonists, only GCA predicted activity for full and partial hPPARα agonists and a full agonist and antagonist. We then generated concentration response curves for seven PFAS, which were well-fit with three-parameter Hill functions. The four perfluorinated carboxylic acids (PFCA) tended to act as full hPPARα agonists while the three perfluorinated sulfonic acids (PFSA) tended to act as partial agonists that varied in efficacy between 28-67 % of the full agonist, positive control level. GCA and RPF performed equally well at predicting the effects of mixtures with three PFCAs, but only GCA predicted experimental activity with mixtures of PFSAs and a mixture of PFCAs and PFSAs at ratios found in the general population. We conclude that of the three approaches, GCA most accurately models the effect of PFAS mixtures on hPPARα activity in vitro. Understanding the differences in efficacy with which PFAS activate hPPARα is essential for accurately predicting the effects of PFAS mixtures. As PFAS can activate multiple nuclear receptors, future analyses should examine mixtures effects in intact cells where multiple molecular initiating events contribute to proximate effects and functional changes.

Exposure to a mixture of legacy, alternative, and replacement per- and polyfluoroalkyl substances (PFAS) results in sex-dependent modulation of cholesterol metabolism and liver injury

BACKGROUND

Epidemiological studies have shown Per- and polyfluoroalkyl substances (PFAS) to be associated with diseases of dysregulated lipid and sterol homeostasis such as steatosis and cardiometabolic disorders. However, the majority of mechanistic studies rely on single chemical exposures instead of identifying mechanisms related to the toxicity of PFAS mixtures.

OBJECTIVES

The goal of the current study is to investigate mechanisms linking exposure to a PFAS mixture with alterations in lipid metabolism, including increased circulating cholesterol and bile acids.

METHODS

Male and female wild-type C57BL/6J mice were fed an atherogenic diet used in previous studies of pollutant-accelerated atherosclerosis and exposed to water containing a mixture of 5 PFAS representing legacy, replacement, and alternative subtypes (i.e., PFOA, PFOS, PFNA, PFHxS, and GenX), each at a concentration of 2 mg/L, for 12 weeks. Changes at the transcriptome and metabolome level were determined by RNA-seq and high-resolution mass spectrometry, respectively.

RESULTS

We observed increased circulating cholesterol, sterol metabolites, and bile acids due to PFAS exposure, with some sexual dimorphic effects. PFAS exposure increased hepatic injury, demonstrated by increased liver weight, hepatic inflammation, and plasma alanine aminotransferase levels. Females displayed increased lobular and portal inflammation compared to the male PFAS-exposed mice. Hepatic transcriptomics analysis revealed PFAS exposure modulated multiple metabolic pathways, including those related to sterols, bile acids, and acyl carnitines, with multiple sex-specific differences observed. Finally, we show that hepatic and circulating levels of PFOA were increased in exposed females compared to males, but this sexual dimorphism was not the same for other PFAS examined.

DISCUSSION

Exposure of mice to a mixture of PFAS results in PFAS-mediated modulation of cholesterol levels, possibly through disruption of enterohepatic circulation.

Varied thyroid disrupting effects of perfluorooctanoic acid (PFOA) and its novel alternatives hexafluoropropylene-oxide-dimer-acid (GenX) and ammonium 4,8-dioxa-3H-perfluorononanoate (ADONA) in vitro

Due to its potential adverse effects on human health, perfluorooctanoic acid (PFOA), one of the once widely used legacy per- and polyfluoroalkyl substances (PFASs), has been recently replaced by its novel alternatives including hexafluoropropylene-oxide-dimer-acid (GenX) and ammonium 4,8-dioxa-3H-perfluorononanoate (ADONA). These alternative PFASs are detected in water and exposed workers. PFASs can enter organs like thyroids, however, it is yet unknown whether the new alternatives are safer than PFOA. In the current study, we compared the thyroid disrupting effects of PFOA and its alternatives GenX and ADONA in vitro with both rat thyroid cell line FRTL5 and primary normal human thyroid (NHT) cells. Cells were exposed to ascendant doses of PFOA, GenX or ADONA for various incubation time and cell viability was assessed by WST-1 assay and LDH assay. The proliferation rate of survived cells was determined by crystal violet-based cell proliferation assay and MTT assay. The gene expression of thyroid hormone regulation-related genes in thyroid cells after exposure was quantified by RT-PCR and Western blot. Our data showed that both PFOA and GenX reduced thyroid cell viability in both dose and time dependent manner, with GenX being more toxic than PFOA at the same condition. Similarly, the proliferation rate of cells survived exposure to PFOA and GenX was considerably impaired, with GenX showing more profound adverse effect than PFOA. Unlike PFOA and GenX, ADONA showed no apparent adverse effects on the viability and proliferation of both thyroid cell types. Gene expression data revealed that all three PFASs altered gene expression in both thyroid cells and the altered gene expression seemed to be PFAS and cell type dependent. Taken together, our data reveal that the thyroid disrupting effects is increased in the order of GenX > PFOA > ADONA. Our findings will be beneficial for the guidance of the future usage of PFASs and development of better alternatives.

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

Associations between per- and polyfluoroalkyl substances (PFASs) and the incidence of type 2 diabetes are controversial in epidemiological studies. In addition, limited data are available for assessing the health effects of novel PFAS alternatives. Our study evaluated the effects of PFAS exposure on type 2 diabetes by estimating the associations of PFASs in human serum with the risk of type 2 diabetes and levels of glycemic biomarkers and lipid fractions. The case-control study consisted of 304 participants from Shandong Province, East China, half of which were diagnosed with type 2 diabetes. Logistic regression showed that most PFASs were inversely associated with the risk of type 2 diabetes after adjusting for age, sex, and body mass index. However, concentrations of perfluorooctanoic acid (PFOA) in the control group were positively associated with fasting plasma glucose levels (β = 0.04, 95% confidence interval (CI): 0.0003, 0.08), which may promote the development of type 2 diabetes. Furthermore, each log-unit increase in the concentrations of perfluorononanoic acid (PFNA), perfluoroundecanoic acid (PFUnDA), and 6:2 chlorinated polyfluoroalkyl ether sulfonic acid (Cl-PFESA) were associated with a total cholesterol increase (i.e., 17.49% (95% CI: 0.93%, 34.90%), 17.49% (95% CI: 4.71%, 31.83%), and 17.49% (95% CI: 4.71%, 31.83%), respectively). Positive associations were also observed between PFNA, PFUnDA, perfluorooctane sulfonate (PFOS), and 6:2 Cl-PFESA and low-density lipoprotein cholesterol. However, no associations between PFASs and hemoglobin A1c, triglycerides, or high-density lipoprotein cholesterol reached statistical significance, nor associations between PFAS mixtures and outcomes of interest. In conclusion, the significant correlations between serum PFASs and glycemic biomarkers and lipid fractions indicated that PFAS exposure may be a potential diabetogenic factor. To the best of our knowledge, this is the first study to assess the associations between novel Cl-PFESAs and type 2 diabetes, although the inverse associations observed require clarification in future studies.

Transcriptional effects of binary combinations of PFAS in FaO cells

Per- and polyfluoroalkyl substances (PFAS) represent a large class of structurally diverse chemicals of increasing public concern, mostly due to their chemical stability and undetermined toxicity profiles. In laboratory animals, adverse effects implicated for certain PFAS, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in particular, include liver toxicity and the associated metabolic dysregulation, immune and thyroid alterations, reproductive toxicity, and selected tumors. The broad commercialization and environmental distribution of PFAS has drawn attention to the need for understanding risks associated with combined exposure to multiple PFAS in complex mixtures. The purpose of this investigation is to determine whether binary combinations of PFAS elicit a molecular response that is either greater than or less than the sum of the individual responses. Exposure of FaO rat hepatoma cells for 24 h to 25 μM-200 μM of the 4- and 8-carbon perfluorocarboxylic acids (PFBA and PFOA) or the 4, 6, and 8-carbon perfluorosulfonic acids (PFBS, PFHxS, and PFOS, respectively) individually caused a dose-dependent increase in PPARα-regulated expression of peroxisomal bifunctional enzyme (Ehhadh). Potency increased with carbon number, with the carboxylates eliciting a greater transcriptional response than the corresponding sulfonates. Combined exposure to PFOA and PFBA produced an effect that was significantly less than the sum of the individual responses. The response to the combination of PFOA and PFOS produced a summative effect at concentrations that were not cytotoxic. Combined exposures to PFOS and either PFBS or PFHxS at low noncytotoxic concentrations produced a transcriptional effect that was significantly less than the sum of the individual effects. The results demonstrate that among the five structurally related perfluoroalkyl acids included in this investigation, PPARα transcriptional activation in response to combined binary exposures is consistently at or below that predicted by the sum of the individual effects.

Plasma Concentrations of Per- and Polyfluoroalkyl Substances and Body Composition From Mid-Childhood to Early Adolescence

CONTEXT

Per- and polyfluoroalkyl substances (PFAS) may alter body composition by lowering anabolic hormones and increasing inflammation, but data are limited, particularly in adolescence when body composition is rapidly changing.

OBJECTIVE

To evaluate associations of PFAS plasma concentrations in childhood with change in body composition through early adolescence.

METHODS

A total of 537 children in the Boston-area Project Viva cohort participated in this study. We used multivariable linear regression and Bayesian kernel machine regression (BKMR) to examine associations of plasma concentrations of 6 PFAS, quantified by mass spectrometry, in mid-childhood (mean age, 7.9 years; 2007-2010) with change in body composition measured by dual-energy x-ray absorptiometry from mid-childhood to early adolescence (mean age, 13.1 years).

RESULTS

In single-PFAS linear regression models, children with higher concentrations of perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorodecanoate (PFDA), and perfluorohexane sulfonate (PFHxS) had less accrual of lean mass (eg, -0.33 [95% CI: -0.52, -0.13] kg/m2 per doubling of PFOA). Children with higher PFOS and PFHxS had less accrual of total and truncal fat mass (eg, -0.32 [95% CI: -0.54, -0.11] kg/m2 total fat mass per doubling of PFOS), particularly subcutaneous fat mass (eg, -17.26 [95% CI -32.25, -2.27] g/m2 per doubling of PFOS). Children with higher PFDA and perfluorononanoate (PFNA) had greater accrual of visceral fat mass (eg, 0.44 [95% CI: 0.13, 0.75] g/m2 per doubling of PFDA). Results from BKMR mixture models were consistent with linear regression analyses.

CONCLUSION

Early life exposure to some but not all PFAS may be associated with adverse changes in body composition.

Perfluorooctanoic acid induces liver and serum dyslipidemia in humanized PPARα mice fed an American diet

Per- and polyfluoroalkyl substances (PFAS) are pervasive in the environment resulting in nearly universal detection in people. Human serum PFAS concentrations are strongly associated with increased serum low-density lipoprotein cholesterol (LDL-C), and growing evidence suggests an association with serum triacylglycerides (TG). Here, we tested the hypothesis that perfluorooctanoic acid (PFOA) dysregulates liver and serum triacylglycerides in human peroxisome proliferator activated receptor α (hPPARα)-expressing mice fed an American diet. Mice were exposed to PFOA (3.5 mg/L) in drinking water for 6 weeks resulting in a serum concentration of 48 ± 9 μg/ml. In male and female hPPARα mice, PFOA increased total liver TG and TG substituted with saturated and monounsaturated fatty acids. Lack of expression of PPARα alone also increased total liver TG, and PFOA treatment had little effect on liver TG in PPARα null mice. In hPPARα mice, PFOA neither significantly increased nor decreased serum TG; however, there was a modest increase in TG associated with very low-density cholesterol particles in both sexes. Intriguingly, in female PPARα null mice, PFOA significantly increased serum TG, with a similar trend in males. PFOA also modified fatty acid and TG homeostasis-related gene expression in liver, in a hPPARα-dependent manner, but not in adipose. The results of our study and others reveal the importance of context (serum concentration and genotype) in determining the effect of PFOA on lipid homeostasis.

Why is elevation of serum cholesterol associated with exposure to perfluoroalkyl substances (PFAS) in humans? A workshop report on potential mechanisms

Serum concentrations of cholesterol are positively correlated with exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) in humans. The associated change in cholesterol is small across a broad range of exposure to PFOA and PFOS. Animal studies generally have not indicated a mechanism that would account for the association in humans. The extent to which the relationship is causal is an open question. Nonetheless, the association is of particular importance because increased serum cholesterol has been considered as an endpoint to derive a point of departure in at least one recent risk assessment. To gain insight into potential mechanisms for the association, both causal and non-causal, an expert workshop was held Oct 31 and Nov 1, 2019 to discuss relevant data and propose new studies. In this report, we summarize the relevant background data, the discussion among the attendees, and their recommendations for further research.

Per- and Polyfluoroalkyl Substances (PFAS) in Breast Milk: Concerning Trends for Current-Use PFAS

This is the first study in the last 15 years to analyze per- and polyfluoroalkyl substances (PFAS) in breast milk collected from mothers (n = 50) in the United States, and our findings indicate that both legacy and current-use PFAS now contaminate breast milk, exposing nursing infants. Breast milk was analyzed for 39 PFAS, including 9 short-chain and 30 long-chain compounds, and 16 of these PFAS were detected in 4-100% of the samples. The ∑PFAS concentration in breast milk ranged from 52.0 to 1850 pg/mL with a median concentration of 121 pg/mL. Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) were the most abundant PFAS in these samples (medians 30.4 and 13.9 pg/mL, respectively). Two short-chain PFAS, including perfluoro-n-hexanoic acid (PFHxA, C6) and perfluoro-n-heptanoic acid (PFHpA, C7), were detected in most of the samples with median concentrations of 9.69 and 6.10 pg/mL, respectively. Analysis of the available breast milk PFAS data from around the world over the period of 1996-2019 showed that while the levels of the phased-out PFOS and PFOA have been declining with halving times of 8.1 and 17 years, respectively, the detection frequencies of current-use short-chain PFAS have been increasing with a doubling time of 4.1 years.

Systemic PFOS and PFOA exposure and disturbed lipid homeostasis in humans: what do we know and what not?

Associations between per- and polyfluoroalkyl substances (PFASs) and increased blood lipids have been repeatedly observed in humans, but a causal relation has been debated. Rodent studies show reverse effects, i.e. decreased blood cholesterol and triglycerides, occurring however at PFAS serum levels at least 100-fold higher than those in humans. This paper aims to present the main issues regarding the modulation of lipid homeostasis by the two most common PFASs, PFOS and PFOA, with emphasis on the underlying mechanisms relevant for humans. Overall, the apparent contrast between human and animal data may be an artifact of dose, with different molecular pathways coming into play upon exposure to PFASs at very low versus high levels. Altogether, the interpretation of existing rodent data on PFOS/PFOA-induced lipid perturbations with respect to the human situation is complex. From a mechanistic perspective, research on human liver cells shows that PFOS/PFOA activate the PPARα pathway, whereas studies on the involvement of other nuclear receptors, like PXR, are less conclusive. Other data indicate that suppression of the nuclear receptor HNF4α signaling pathway, as well as perturbations of bile acid metabolism and transport might be important cellular events that require further investigation. Future studies with human-relevant test systems would help to obtain more insight into the mechanistic pathways pertinent for humans. These studies shall be designed with a careful consideration of appropriate dosing and toxicokinetics, so as to enable biologically plausible quantitative extrapolations. Such research will increase the understanding of possible perturbed lipid homeostasis related to PFOS/ PFOA exposure and the potential implications for human health.

Gaussian graphical modeling of the serum exposome and metabolome reveals interactions between environmental chemicals and endogenous metabolites

Given the complex exposures from both exogenous and endogenous sources that an individual experiences during life, exposome-wide association studies that interrogate levels of small molecules in biospecimens have been proposed for discovering causes of chronic diseases. We conducted a study to explore associations between environmental chemicals and endogenous molecules using Gaussian graphical models (GGMs) of non-targeted metabolomics data measured in a cohort of California women firefighters and office workers. GGMs revealed many exposure-metabolite associations, including that exposures to mono-hydroxyisononyl phthalate, ethyl paraben and 4-ethylbenzoic acid were associated with metabolites involved in steroid hormone biosynthesis, and perfluoroalkyl substances were linked to bile acids-hormones that regulate cholesterol and glucose metabolism-and inflammatory signaling molecules. Some hypotheses generated from these findings were confirmed by analysis of data from the National Health and Nutrition Examination Survey. Taken together, our findings demonstrate a novel approach to discovering associations between chemical exposures and biological processes of potential relevance for disease causation.

Assessing the human health risks of per- and polyfluoroalkyl substances: A need for greater focus on their interactions as mixtures

Humans are exposed to complex mixtures of per- and polyfluoroalkyl substances (PFAS). However, human health risk assessment of PFAS currently relies on animal toxicity data derived from individual substance exposure, which may not adequately predict the risk from combined exposure due to possible interactions that can influence the overall risk. Long-chain perfluoroalkyl acids (PFAAs), particularly perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are recognised as global emerging contaminants of concern due to their ubiquitous distribution in all environmental media, wildlife, and humans, persistency, bioaccumulative-, toxic-, and human health-risk potentials. This article reviews the current understanding of the human health risks associated with PFAS exposure focusing on more recent toxicological and epidemiological studies from 2010 to 2020. The existing information on PFAA mixtures was also reviewed in an attempt to highlight the need for greater focus on their potential interactions as mixtures within the class of these chemicals. A growing number of toxicological studies have indicated several adverse health outcomes of PFAA exposure, including developmental and reproductive toxicity, neurotoxicity, hepatotoxicity, genotoxicity, immunotoxicity, thyroid disruption, and carcinogenicity. Epidemiological findings further support some of these adverse human health outcomes. However, the mechanisms underlying these adverse effects are not well defined. A few in vitro studies focusing on PFAA mixtures revealed that these compounds may act additively or interact synergistically/antagonistically depending on the species, dose level, dose ratio, and mixture components. Hence, the combined effects or potential interactions of PFAS mixtures should be considered and integrated into toxicity assessment to obtain a realistic and more refined human health risk assessment.

Bioaccumulation, trophic transfer and biomagnification of perfluoroalkyl acids (PFAAs) in the marine food web of the South China Sea

Knowledge about bioaccumulation and trophic transfer in food webs is of tremendous importance in contaminant hazards evaluation. Perfluoroalkyl acids (PFAAs) are widely distributed, and its emissions to coastal areas have posed a threat to the health of marine organisms and consumers. In this study, 15 species were sampled from Qinzhou Bay of the South China Sea. The concentrations of PFAAs in organisms were detected by liquid chromatography-mass spectrometry, and the trophic positions of organisms were constructed based on nitrogen isotope analysis. PFAAs were found in all organisms. The contents of PFOS in all organisms were higher than of PFOA, and the proportions of short-chain PFAAs were higher in the low trophic positioned organisms, while long-chain PFAAs were higher in the high trophic positioned organisms. Moreover, the bioaccumulation factors (BAFs) increased with the increasing number of fluorocarbon atoms. The trophic magnification factor (TMF) and the biomagnification factors (BMFs), calculated from the constructed food webs, together suggested potential biomagnification effects of PFOS, while less clear results were found for PFOA. Our results further indicate that previously banned long-chain PFAAs had persistent residuals in this coastal marine ecosystem, and that emerging short-chain PFAAs had high concentrations in some species but showed no biomagnification.

Per- and Polyfluoroalkyl Substance Toxicity and Human Health Review: Current State of Knowledge and Strategies for Informing Future Research

Reports of environmental and human health impacts of per- and polyfluoroalkyl substances (PFAS) have greatly increased in the peer-reviewed literature. The goals of the present review are to assess the state of the science regarding toxicological effects of PFAS and to develop strategies for advancing knowledge on the health effects of this large family of chemicals. Currently, much of the toxicity data available for PFAS are for a handful of chemicals, primarily legacy PFAS such as perfluorooctanoic acid and perfluorooctane sulfonate. Epidemiological studies have revealed associations between exposure to specific PFAS and a variety of health effects, including altered immune and thyroid function, liver disease, lipid and insulin dysregulation, kidney disease, adverse reproductive and developmental outcomes, and cancer. Concordance with experimental animal data exists for many of these effects. However, information on modes of action and adverse outcome pathways must be expanded, and profound differences in PFAS toxicokinetic properties must be considered in understanding differences in responses between the sexes and among species and life stages. With many health effects noted for a relatively few example compounds and hundreds of other PFAS in commerce lacking toxicity data, more contemporary and high-throughput approaches such as read-across, molecular dynamics, and protein modeling are proposed to accelerate the development of toxicity information on emerging and legacy PFAS, individually and as mixtures. In addition, an appropriate degree of precaution, given what is already known from the PFAS examples noted, may be needed to protect human health. Environ Toxicol Chem 2021;40:606-630. © 2020 SETAC.

Per- and polyfluoroalkyl substance plasma concentrations and metabolomic markers of type 2 diabetes in the Diabetes Prevention Program trial

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are widely used chemicals, some of which have been linked to type 2 diabetes. We tested whether PFAS concentrations were cross-sectionally associated with metabolites previously shown to predict incident type 2 diabetes using the Diabetes Prevention Program (DPP), a trial of individuals at high risk of type 2 diabetes.

METHODS

We evaluated 691 participants enrolled in the DPP with baseline measures of 10 PFAS (including total perfluorooctanesulfonic acid (PFOS), total perfluorooctanoic acid (PFOA), and Sb-PFOA [branched isomers of PFOA]) and 77 metabolites. We used log2-transformed PFAS concentrations as exposures and standardized metabolite concentrations as outcomes in linear regression models adjusted for age, sex, race/ethnicity, use of anti-hyperlipidemic or triglyceride-lowering medication, income, years of education, marital status, smoking, and family history of diabetes, with Benjamini-Hochberg linear step-up false discovery rate correction.

RESULTS

Sb-PFOA was associated with the largest number of tested metabolites (29 of 77). Each doubling in Sb-PFOA was associated with higher leucine (β = 0.07 [95%CI: 0.02, 0.11] SD) and lower glycine (-0.08 [95%CI: 0.03, -0.13] SD). Each doubling of either total PFOA or n-PFOA was associated with -0.13 [95%CI: 0.04, -0.22] SD lower glycine. PFOA and Sb-PFOA were positively associated with multiple triacylglycerols and diacylglycerols, and total PFOS, total PFOA, and Sb-PFOA were positively associated with phosphatidylethanolamines.

CONCLUSIONS

PFAS concentrations are associated with metabolites linked to type 2 diabetes (particularly amino acid, glycerolipid and glycerophospholipid pathways). Further prospective research is needed to test whether these metabolites mediate associations of PFAS and type 2 diabetes.

Application of a Framework for Grouping and Mixtures Toxicity Assessment of PFAS: A Closer Examination of Dose-Additivity Approaches

Environmental occurrence and biomonitoring data for per- and polyfluoroalkyl substances (PFAS) demonstrate that humans are exposed to mixtures of PFAS. This article presents a new and systematic analysis of available PFAS toxicity study data using a tiered mixtures risk assessment framework consistent with United States and international mixtures guidance. The lines of evidence presented herein include a critique of whole mixture toxicity studies and analysis of dose-response models based on data from subchronic oral toxicity studies in rats. Based on available data to-date, concentration addition and relative potency factor methods are found to be inappropriate due to differences among sensitive effects and target organ potencies and noncongruent dose-response curves for the same effect endpoints from studies using the same species and protocols. Perfluorooctanoic acid and perfluorooctane sulfonic acid lack a single mode of action or molecular initiating event and our evaluation herein shows they also have noncongruent dose-response curves. Dose-response curves for long-chain perfluoroalkyl sulfonic acids (PFSAs) also significantly differ in shapes of the curves from short-chain PFSAs and perfluoroalkyl carboxylic acids evaluated, and additional differences are apparent when curves are evaluated based on internal or administered dose. Following well-established guidance, the hazard index method applied to perfluoroalkyl carboxylic acids and PFSAs grouped separately is the most appropriate approach for conducting a screening level risk assessment for nonpolymeric PFAS mixtures, given the current state-of-the science. A clear presentation of assumptions, uncertainties, and data gaps is needed before dose-additivity methods, including hazard index , are used to support risk management decisions. Adverse outcome pathway(s) and mode(s) of action information for perfluorooctanoic acid and perfluorooctane sulfonic acid and for other nonpolymer PFAS are key data gaps precluding more robust mixtures methods. These findings can guide the prioritization of future studies on single chemical and whole mixture toxicity studies.

Multilayered glycoproteomic analysis reveals the hepatotoxic mechanism in perfluorooctane sulfonate (PFOS) exposure mice

Perfluorooctane sulfonate (PFOS) is one of the most widely used and distributed perfluorinated compounds proven to cause adverse health outcomes. Datasets of ecotoxico-genomics and proteomics have given greater insights for PFOS toxicological effect. However, the molecular mechanisms of hepatotoxicity of PFOS on post-translational modifications (PTMs) regulation, which is most relevant for regulating the activity of proteins, are not well elucidated. Protein glycosylation is one of the most ubiquitous PTMs associated with diverse cellular functions, which are critical towards the understanding of the multiple biological processes and toxic mechanisms exposed to PFOS. Here, we exploit the multilayered glycoproteomics to quantify the global protein expression levels, glycosylation sites, and glycoproteins in PFOS exposure and wild-type mouse livers. The identified 2439 proteins, 1292 glycosites, and 799 glycoproteins were displayed complex heterogeneity in PFOS exposure mouse livers. Quantification results reveal that 241 dysregulated proteins (fold change ≥ 2, p < 0.05) in PFOS exposure mouse livers were involved in the lipid and xenobiotic metabolism. While, 16 overexpressed glycoproteins were exclusively related to neutrophil degranulation, cellular responses to stress, protein processing in endoplasmic reticulum (ER). Moreover, the interactome and functional network analysis identified HP and HSP90AA1 as the potential glycoprotein biomarkers. These results provide unique insights into a deep understanding of the mechanisms of PFOS induced hepatotoxicity and liver disease. Our platform of multilayered glycoproteomics can be adapted to diverse ecotoxicological research.

Diet as an Exposure Source and Mediator of Per- and Polyfluoroalkyl Substance (PFAS) Toxicity

Per- and polyfluoroalkyl substances (PFAS) are ubiquitously found in the environment due to their widespread commercial use and high chemical stability. Humans are exposed primarily through ingestion of contaminated water and food and epidemiological studies over the last several decades have shown that PFAS levels are associated with adverse chronic health effects, including cardiometabolic disorders such as hyperlipidemia and non-alcoholic fatty liver disease. Perhaps the most well-established effects, as demonstrated in animal studies and human epidemiological studies, are the metabolic alterations PFAS exposure can lead to, especially on lipid homeostasis and signaling. This altered lipid metabolism has often been linked to conditions such as dyslipidemia, leading to fatty liver disease and steatosis. Western diets enriched in high fat and high cholesterol containing foods may be an important human exposure route of PFAS and may also act as an important modulator of associated toxicities. In fact, the chemical structure of PFAS resemble fatty acids and may activate some of the same signaling cascades critical for endogenous metabolism. In this review we aim to outline known dietary exposure sources of PFAS, describe the detrimental metabolic health effects associated with PFAS exposure, and focus on studies examining emerging interaction of dietary effects with PFAS exposure that further alter the dysregulated metabolic state.