Early Life Exposures to Perfluoroalkyl Substances in Relation to Adipokine Hormone Levels at Birth and During Childhood

Prenatal per- and polyfluoroalkyl substance mixtures and weight for length from birth to 12 months: The New Hampshire Birth Cohort Study

OBJECTIVE

To examine the joint associations of plasma concentrations of prenatal per- and polyfluoroalkyl substances (PFAS) mixtures with birth size and postnatal anthropometry measures.

MATERIAL AND METHODS

The current study included 641 mother-child dyads from the New Hampshire Birth Cohort Study. PFAS concentrations were quantified in maternal plasma samples collected during pregnancy (median: 28 weeks of gestation). Information on infant weight and length were abstracted from medical records and converted to sex- and age-standardized weight-for-length z-score according to the World Health Organization standard curves. Bayesian kernel machine regression (BKMR) was used to investigate the joint associations of multiple PFAS concentrations during pregnancy with weight-for-length z score at birth, 6-months, and 12-months. To account for longitudinal outcomes, we also fit linear mixed effect models between PFAS exposure burden score, a novel method to quantify total exposure burden to PFAS mixtures, and changes in weight-for-length from birth to 12 months of age. A multiplicative interaction term ("PFAS burden score × time [birth as a reference, 6 months, and 12 months of age]") was included to evaluate a potential time-varying relationship. All models were adjusted for maternal age, education, marital status, parity, smoking, seafood consumption, pre-pregnancy body mass index, and gestational week of blood draw.

RESULTS

In BKMR models, all 95 % credible intervals included the null value. In linear mixed effects models, PFAS exposure burden score was associated with a lower weight-for-length z-score (β = -0.20; 95 % confidence interval = -0.35, -0.04). The multiplicative interaction term was significant at both 6 and 12 months of age (P < 0.01 for both time points), particularly among female infants, suggesting a shift toward positive associations between the prenatal PFAS mixtures and weight-for-length z-score during infancy.

CONCLUSIONS

Prenatal PFAS mixtures may affect fetal and infant anthropometry measures differently by life stage and biological sex.

Unveiling the Research Void: Exploring the Reproductive Effects of PFAS Compounds on Male Health

Per- and polyfluoroalkyl substances (PFAS) represent an emerging concern for male reproductive health. Epidemiological studies have reported associations between increased PFAS exposure and reduced semen quality parameters, lower sperm counts, and potential alterations in reproductive hormone levels. Toxicology research has revealed possible mechanisms including blood-testis barrier disruption, oxidative stress, interference with testicular cell function, and epigenetic changes. However, significant uncertainties remain regarding definitive exposure-response relationships, developmental windows of heightened vulnerability, combined mixture effects, and causality interpretation, given limitations inherent to observational studies. Ongoing investigation of short-chain and replacement PFAS compounds is also critically needed. Additionally, directly connecting the mechanistic insights from animal models to human fertility impacts remains challenging. While controlled toxicology studies have described pathways by which PFAS could impair cellular functioning in the testes, uncertainty persists in extrapolating these experimental effects to real-world human exposures and sperm parameter declines reported epidemiologically. Overall, current findings suggest PFAS may contribute to declining male reproductive function, but additional clarification through well-designed longitudinal cohort studies integrated with mechanistic animal work is still warranted to confirm exposure-fertility links across a range of PFAS types and inform evidence-based public health mitigation strategies.

Maternal PFOS exposure in mice induces hepatic lipid accumulation and inflammation in adult female offspring: Involvement of microbiome-gut-liver axis and autophagy

Perfluorooctane sulfonates (PFOS) are the persistent organic pollutants. In the present study, 0, 0.3, or 3-mg/kg PFOS were administered to pregnant mice from GD 11 to GD 18. The histopathology of liver and intestine, serum and hepatic lipid levels, lipid metabolism related genes, and gut microbiota were examined in adult female offspring. The results suggested that maternal PFOS exposure increased serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and induced F4/80+ macrophage infiltration in adult female offspring, in addition to the elevation of TNF-α and IL-1β mRNA levels in low-dose and high-dose groups, respectively. Furthermore, maternal exposure to PFOS increased serum triglyceride (TG) and hepatic total cholesterol (TC) levels, which was associated with the alteration of the process of fatty acid transport and β-oxidation, TG synthesis and transport, cholesterol synthesis and excretion in the liver. The AMPK/mTOR/autophagy signaling was also inhibited in the liver of adult female offspring. Moreover, changes in gut microbiota were also related to lipid metabolism, especially for the Desulfovibrio, Ligilactobacillus, Enterorhabdus, HT002 and Peptococcaceae_unclassified. Additionally, maternal exposure to PFOS decreased mRNA expressions of the tight junction protein and AB+ goblet cells in the colon, while increasing the overproduction of lipopolysaccharides (LPS) and F4/80+ macrophage infiltration. Collectively, maternal PFOS exposure induced liver lipid accumulation and inflammation, which strongly correlated with the disruption of the gut-liver axis and autophagy in adult female offspring, highlighting the persistent adverse effects in offspring exposed to PFOS.

Estimated exposure to perfluoroalkyl substances during infancy and serum-adipokine concentrations in later childhood

BACKGROUND

Perfluoroalkyl substances (PFASs) are transferred through human milk and may cause elevated exposure during infancy. Given the lack of early postnatal blood samples, PFAS concentrations can be estimated to serve as predictors of subsequent metabolic toxicity.

METHODS

A total of 298 children from a prospective birth cohort were followed up through to age 9 years. Serum-PFAS was measured at birth and 18 months of age, while exposures during infancy were estimated by structural equations. Adiponectin, resistin, leptin, and the leptin receptor were measured in serum at age 9. Adjusted regression coefficients for estimated serum-PFAS concentrations were calculated, with additional consideration of the duration of breastfeeding and potential effect modification by sex.

RESULTS

A doubling in estimated serum-PFAS concentrations, particularly at ages 6 and 12 months, was associated with a loss of about 10-15% in age 9 resistin concentrations, while other associations were much weaker. Sex dependence of the associations was not observed, and neither did the duration of breastfeeding affect outcomes at age 9.

CONCLUSION

Lowered serum-resistin concentrations at age 9 years were most strongly associated with early postnatal PFAS exposures. These findings suggest that infancy may represent a vulnerable time window for some aspects of metabolic programming that may be affected by PFAS exposure.

IMPACT

Serum-PFAS concentrations during infancy can be estimated in the absence of blood samples. Adipokine concentrations were measured at age 9 years as metabolic biomarkers. Resistin was significantly lower in children with elevated PFAS exposures in infancy. The findings suggest that early postnatal PFAS exposures may affect subsequent metabolic health. Assessment of infancy vulnerability to PFAS can be explored using estimated serum-PFAS concentrations.

Associations of perfluoroalkyl substances with adipocytokines in umbilical cord serum: A mixtures approach

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS), a kind of emerging environmental endocrine disruptors, may interfere with the secretion of adipokines and affect fetal metabolic function and intrauterine development. However, the epidemiological evidence is limited and inconsistent. We examined the associations of single and multiple PFAS exposures in utero with adipocytokine concentrations in umbilical cord serum.

METHODS

This study included 1111 mother-infant pairs from Sheyang Mini Birth Cohort Study (SMBCS), and quantified 12 PFAS and two adipokine in umbilical cord serum. Generalized linear models (GLMs) and Bayesian Kernel Machine Regression (BKMR) models were applied to estimate the associations of single- and mixed- PFAS exposure with adipokines, respectively. Furthermore, sex-stratification was done in each model to assess the sexually dimorphic effects of PFAS.

RESULTS

10 PFAS were detected with median concentrations (μg/L) ranging from 0.04 to 3.97, (except 2.7% for PFOSA and 1.7% for PFDS, which were excluded). In GLMs, for each doubling increase in PFBS, PFHpA, PFHxS, PFHpS, PFUnDA and PFDoDA, leptin decreased between 14.04% for PFBS and 22.69% for PFHpS (P < 0.05). PFAS, except for PFNA, were positively associated with adiponectin, and for each doubling of PFAS, adiponectin increased between 3.27% for PFBS and 12.28% for PFHxS (P < 0.05). In addition, infant gender modified the associations of PFAS with adipokines, especially the associations of PFBS, PFOA and PFHxS with adiponectin. Similarly, significant associations of PFAS mixtures with leptin and adiponectin were observed in the BKMR models. PFDA, PFOS, PFNA and PFHpS were identified as important contributors. In the sex-stratified analysis of BKMR models, the associations between PFAS mixtures and adipokines were more pronounced in males.

CONCLUSIONS

PFAS levels were significantly associated with adipokines in cord serum, suggesting that intrauterine mixture of PFAS exposure may be related to decreased fetal leptin level but increased fetal adiponectin level and the associations may be sex-specific.

Developing an Exposure Burden Score for Chemical Mixtures Using Item Response Theory, with Applications to PFAS Mixtures

BACKGROUND

There are few existing methods to quantify total exposure burden to chemical mixtures, independent of a health outcome. A summary metric could be advantageous for use in biomonitoring, risk assessment, health risk calculators, and mediation models.

OBJECTIVE

We developed a novel exposure burden score method for chemical mixtures, applied it to estimate exposure burden to per- and polyfluoroalkyl substances (PFAS) mixtures, and estimated associations of PFAS burden scores with cardio-metabolic outcomes in the general U.S.

POPULATION

METHODS

We applied item response theory (IRT) to biomonitoring data from 1,915 children and adults 12-80 years of age in the 2017-2018 National Health and Examination Survey to quantify a latent PFAS burden score, using serum concentrations of eight measured PFAS biomarkers, each considered an "item." The premise of IRT is that through using both information about a participant's concentration of an individual PFAS biomarker, as well as their exposure patterns for the PFAS mixture, we can estimate the participant's latent PFAS exposure burden, independent of a health outcome. We used linear regression to estimate associations of the PFAS burden score with cardio-metabolic outcomes and compared our findings to results using summed PFAS concentrations as the exposure metric.

RESULTS

PFAS burden scores and summed PFAS concentrations had moderate-high correlation (ρ=0.75). Isomers of PFOS [n-perfluorooctane sulfonic acid (n-PFOS) and perfluoromethylheptane sulfonic acid isomers (Sm-PFOS)] were the most informative to the PFAS burden scores. PFAS burden scores and summed PFAS concentrations were both significantly associated with cardio-metabolic outcomes, but associations were generally closer to the null for summed PFAS concentrations vs. the PFAS burden score. Adjusted associations (95% CIs) with total cholesterol (in milligrams per deciliter) were 8.6 (95% CI: 5.2, 11.9) and 2.4 (95% CI: 0.5, 4.2) per interquartile range increase in the PFAS burden score and summed concentrations, respectively. Sensitivity analyses showed similar associations with cardio-metabolic outcomes when only a subset of PFAS biomarkers was used to estimate PFAS burden. In a validation study, associations between PFAS burden scores and cholesterol were consistent with primary analyses but null when using summed PFAS concentrations.

DISCUSSION

IRT offers a straightforward way to include exposure biomarkers with low detection frequencies and can reduce exposure measurement error. Further, IRT enables comparisons of exposure burden to chemical mixtures across studies even if they did not measure the exact same set of chemicals, which supports harmonization across studies and consortia. We provide an accompanying PFAS burden calculator (https://pfasburden.shinyapps.io/app_pfas_burden/), enabling researchers to calculate PFAS burden scores based on U.S. population exposure reference ranges. https://doi.org/10.1289/EHP10125.

Understanding exposures and latent disease risk within the National Institute of Environmental Health Sciences Superfund Research Program

Understanding the health effects of exposures when there is a lag between exposure and the onset of disease is an important and challenging topic in environmental health research. The National Institute of Environmental Health Sciences (NIEHS) Superfund Basic Research and Training Program (SRP) is a National Institutes of Health (NIH) grant program that uses a multidisciplinary approach to support biomedical and environmental science and engineering research. Because of the multidisciplinary nature of the program, SRP grantees are well-positioned to study exposure and latent disease risk across humans, animal models, and various life stages. SRP-funded scientists are working to address the challenge of connecting exposures that occur early in life and prior to conception with diseases that manifest much later, including developing new tools and approaches to predict how chemicals may affect long-term health. Here, we highlight research from the SRP focused on understanding the health effects of exposures with a lag between exposure and the onset of the disease as well as provide future directions for addressing knowledge gaps for this highly complex and challenging topic. Advancing the knowledge of latency to disease will require a multidisciplinary approach to research, the need for data sharing and integration, and new tools and computation approaches to make better predications about the timing of disease onset. A better understanding of exposures that may contribute to later-life diseases is essential to supporting the implementation of prevention and intervention strategies to reduce or modulate exposures to reduce disease burden.

Early-life exposure to perfluoroalkyl substances in relation to serum adipokines in a longitudinal birth cohort

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) exposure has been linked to metabolic health outcomes such as obesity, and changes in adipokine hormones may be one of the underlying biological mechanisms. We prospectively evaluated the associations between prenatal and early childhood exposures to PFASs and adipokines in children.

MATERIAL AND METHODS

PFAS concentrations were measured in serum samples collected at birth, 18 months, and 5 and 9 years, and adiponectin, leptin, leptin receptor, and resistin were measured in serum samples collected at birth and 9 years. We used multivariable linear regression models to estimate the percent change in serum-adipokine concentrations for a doubling in serum-PFAS concentrations. The potential sex-specific effect of PFAS was assessed by including an interaction term between PFAS and sex in each model. Bayesian kernel machine regression (BKMR) was implemented to evaluate the overall effect of PFAS mixtures.

RESULTS

Significant associations with leptin, leptin receptor, and resistin at age 9 years were observed for serum-PFAS concentrations at 18 months and 5 and 9 years, whereas associations for PFAS concentrations at birth were mostly null. However, we observed a positive association between serum-PFHxS at birth and leptin receptor at birth. We found limited evidence regarding modification effect of sex on serum-PFAS concentrations. BKMR findings were consistent and suggested some significant effects of the overall PFAS mixtures at 18 months and 5 and 9 years on adipokine concentrations at 9 years.

CONCLUSIONS

Given the associations of PFAS exposure with both adipokine hormones and metabolic functions, future studies should include assessment of adipokine hormones when examining PFAS-associated metabolic alterations.

The role of maternal high fat diet on mouse pup metabolic endpoints following perinatal PFAS and PFAS mixture exposure

Per- and polyfluoroalkyl substances (PFAS) are a family of chemicals that are ubiquitous in the environment. Some of these chemicals, such as perfluorooctanesulfonic acid (PFOS), perfluorohexanesulfonate (PFHxS) and perfluorooctanoic acid (PFOA), are found in human sera and have been shown to cause liver steatosis and reduce postnatal survival and growth in rodents. The purpose of this work is to evaluate the impact of diet and PFAS exposure to mouse dam (mus musculus) on the risk to pup liver and metabolism endpoints later in life, as well as evaluate PFAS partitioning to pups. Timed-pregnant dams were fed a standard chow diet or 60 % kcal high fat diet (HFD). Dams were administered either vehicle, 1 mg/kg PFOA, 1 mg/kg PFOS, 1 mg/kg PFHxS, or a PFAS mixture (1 mg/kg of each PFOA, PFOS, and PFHxS) daily via oral gavage from gestation day 1 until postnatal day (PND) 20. At PND 21, livers of dams and 2 pups of each sex were evaluated for lipid changes while remaining pups were weaned to the same diet as the dam for an additional 10 weeks. Dam and pup serum at PND 21 and PND 90 were also evaluated for PFAS concentration, alanine aminotransferase (ALT), leptin and adiponectin, and glycosylated hemoglobin A1c. Perinatal exposure to a HFD, as expected, increased pup body weight, maternal liver weight, pup liver triglycerides, pup serum ALT, and pup serum leptin. PFOA and the PFAS mixture increased liver weights, and. treatment with all three compounds increased liver triglycerides. The maternal HFD increased dam and pup serum PFAS levels, however, was protective against PFOA-induced increase in serum ALT and observed increases in liver triglycerides. The PFAS mixture had very distinct effects when compared to single compound treatment, suggesting some cumulative effects, particularly when evaluating PFAS transfer from dam to pup. This data highlights the importance of diet and mixtures when evaluating liver effect of PFAS and PFAS partitioning.

Life-course Exposure to Perfluoroalkyl Substances in Relation to Markers of Glucose Homeostasis in Early Adulthood

OBJECTIVE

To investigate the prospective associations of life-course perfluoroalkyl substances (PFASs) exposure with glucose homeostasis at adulthood.

METHODS

We calculated insulin sensitivity and beta-cell function indices based on 2-h oral glucose tolerance tests at age 28 in 699 Faroese born in 1986-1987. Five major PFASs were measured in cord whole blood and in serum from ages 7, 14, 22, and 28 years. We evaluated the associations with glucose homeostasis measures by PFAS exposures at different ages using multiple informant models fitting generalized estimating equations and by life-course PFAS exposures using structural equation models.

RESULTS

Associations were stronger for perfluorooctane sulfonate (PFOS) and suggested decreased insulin sensitivity and increased beta-cell function-for example, β (95% CI) for log-insulinogenic index per PFOS doubling = 0.12 (0.02, 0.22) for prenatal exposures, 0.04 (-0.10, 0.19) at age 7, 0.07 (-0.07, 0.21) at age 14, 0.05 (-0.04, 0.15) at age 22, and 0.04 (-0.03, 0.11) at age 28. Associations were consistent across ages (P for age interaction > 0.10 for all PFASs) and sex (P for sex interaction > 0.10 for all PFASs, except perfluorodecanoic acid). The overall life-course PFOS exposure was also associated with altered glucose homeostasis (P = 0.04). Associations for other life-course PFAS exposures were nonsignificant.

CONCLUSIONS

Life-course PFAS exposure is associated with decreased insulin sensitivity and increased pancreatic beta-cell function in young adults.

Per- and polyfluoroalkyl substances (PFAS) as contaminants of emerging concern in Asia's freshwater resources

The occurrence of per- and polyfluoroalkyl substances (PFAS) in water resources is an emerging concern because of their environmental persistence and bioaccumulation in humans. In Western countries, health advisories regarding PFAS exposure have been released to warn the public of its potential adverse effects. However, awareness regarding PFAS exposure in Asia is still at its infancy as reflected by the minimal safeguards imposed to protect the population from exposure. Here, we reviewed studies on PFAS contamination in Asia with a focus on freshwater resources to determine whether PFAS is also a concern in this part of the globe. Peer reviewed articles which included information on PFAS levels from 2000 to 2020 were compiled. The highest PFAS contamination was detected in surface water relative to ground, tap, and drinking water. PFAS levels in water resources in several countries in Asia, such as China, Japan, and South Korea, were above the recommended level, similar to that in the United States. PFAS in South and Southeast Asia were just below the recommended level, but the rise of PFAS in China in the recent decade, alongside its remarkable economic and industrial growth, suggests that increased PFAS contamination in South and Southeast Asia may soon follow, as these countries compete with the global economy. Hence, there is a need for these countries to also implement measures that will reduce the exposure of their population to PFAS.

Gestational and childhood exposure to per- and polyfluoroalkyl substances and cardiometabolic risk at age 12 years

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) may adversely influence cardiometabolic risk. However, few studies have examined if the timing of early life PFAS exposure modifies their relation to cardiometabolic risk. We examined the influence of gestational and childhood PFAS exposure on adolescents' cardiometabolic risk.

METHODS

We quantified concentrations of four PFAS (perfluorooctanoate [PFOA], perfluorooctane sulfonate [PFOS], perfluorononanoate [PFNA], and perfluorohexane sulfonate [PFHxS]) in sera collected during pregnancy, at birth, and at ages 3, 8, and 12 years from 221 mother-child pairs in the HOME Study (enrolled 2003-06, Cincinnati, Ohio). We measured cardiometabolic risk factors using physical examinations, fasting serum biomarkers, and dual-energy X-ray absorptiometry scans at age 12 years. Cardiometabolic risk summary scores were calculated by summing age- and sex-standardized z-scores for individual cardiometabolic risk factors. We used multiple informant models to estimate covariate-adjusted associations of serum PFAS concentrations (log2-transformed) at each visit with cardiometabolic risk scores and their individual components, and tested for differences in associations across visits.

RESULTS

The associations of serum PFOA concentrations with cardiometabolic risk scores differed across visits (P for heterogeneity = 0.03). Gestational and cord serum PFOA concentrations were positively associated with cardiometabolic risk scores (βs and 95% confidence intervals [95% CIs]: gestational 0.8 [0.0, 1.6]; cord 0.9 [-0.1, 1.9] per interquartile range increase). These positive associations were primarily driven by homeostatic model assessment for insulin resistance index (β = 0.3 [0.1, 0.5]) and adiponectin to leptin ratio (β = -0.5 [-1.0, 0.0]). Other individual cardiometabolic risk factors associated with gestational PFOA included insulin and waist circumference. Gestational and cord PFHxS were also associated with higher cardiometabolic risk scores (βs: gestational 0.9 [0.2, 1.6]; cord 0.9 [0.1, 1.7]).

CONCLUSION

In this cohort of children with higher gestational PFOA exposure, fetal exposure to PFOA and PFHxS was associated with unfavorable cardiometabolic risk in adolescence.

Exposure to perfluoroalkylated substances (PFAS) in relation to fitness, physical activity, and adipokine levels in childhood: The european youth heart study

BACKGROUND

perfluoroalkylated substances (PFAS) are highly persistent chemicals that are able to alter the human metabolism - potentially via disruption of cell signaling pathways mediated by adipokines. Both adiponectin and leptin are influenced by and exert influence on energy storage and energy expenditure, wherefore associations between PFAS and adipokines may be mediated by fitness and fat mass.

OBJECTIVES

the aim of this cross-sectional study was to investigate the association between childhood exposure to PFAS and adipokines (adiponectin and leptin), while considering associations between PFAS and children's level of fitness, physical activity and fat mass to elucidate potential mediation by fitness, physical activity and fat mass.

METHODS

9-year old children from Danish public schools were recruited in the European Youth Heart Study in 1997. For this study only children with valid measures on PFAS (PFOS, PFOA, PFNA, PFDA and PFHxS), adipokines (adiponectin and leptin), fitness, fat mass and co-variates (parity and maternal income) were included (N = 242). Multiple linear regression models with and without conditioning and causal mediation analysis were applied.

RESULTS

this study found inverse associations between PFOA, PFDA and PFHxS and leptin. PFOA was positively associated with adiponectin, whereas PFHxS was inversely associated with adiponectin in boys. Latter association seemed to be mediated by fat mass. Associations with leptin showed indirect effects of fitness and fat mass but were unable to demonstrate significant mediation. Neither PFOS nor PFNA were associated with the outcome.

DISCUSSION

these results may indicate a favorable leptin profile with increasing PFAS, although the results could be driven by residual negative confounding from socio-economic factors and mediation by fitness and fat mass.

Prenatal Exposure to Perfluoroalkyl Substances Associated With Increased Susceptibility to Liver Injury in Children

BACKGROUND AND AIMS

Per- and polyfluoroalkyl substances (PFAS) are widespread and persistent pollutants that have been shown to have hepatotoxic effects in animal models. However, human evidence is scarce. We evaluated how prenatal exposure to PFAS associates with established serum biomarkers of liver injury and alterations in serum metabolome in children.

APPROACH AND RESULTS

We used data from 1,105 mothers and their children (median age, 8.2 years; interquartile range, 6.6-9.1) from the European Human Early-Life Exposome cohort (consisting of six existing population-based birth cohorts in France, Greece, Lithuania, Norway, Spain, and the United Kingdom). We measured concentrations of perfluorooctane sulfonate, perfluorooctanoate, perfluorononanoate, perfluorohexane sulfonate, and perfluoroundecanoate in maternal blood. We assessed concentrations of alanine aminotransferase, aspartate aminotransferase, and gamma-glutamyltransferase in child serum. Using Bayesian kernel machine regression, we found that higher exposure to PFAS during pregnancy was associated with higher liver enzyme levels in children. We also measured child serum metabolomics through a targeted assay and found significant perturbations in amino acid and glycerophospholipid metabolism associated with prenatal PFAS. A latent variable analysis identified a profile of children at high risk of liver injury (odds ratio, 1.56; 95% confidence interval, 1.21-1.92) that was characterized by high prenatal exposure to PFAS and increased serum levels of branched-chain amino acids (valine, leucine, and isoleucine), aromatic amino acids (tryptophan and phenylalanine), and glycerophospholipids (phosphatidylcholine [PC] aa C36:1 and Lyso-PC a C18:1).

CONCLUSIONS

Developmental exposure to PFAS can contribute to pediatric liver injury.

Perfluorooctanesulfonic acid (PFOS) administration shifts the hepatic proteome and augments dietary outcomes related to hepatic steatosis in mice

Hepatic steatosis increases risk of fatty liver and cardiovascular disease. Perfluorooctanesulfonic acid (PFOS) is a persistent, bio-accumulative pollutant that has been used in industrial and commercial applications. PFOS administration induces hepatic steatosis in rodents and increases lipogenic gene expression signatures in cultured hepatocytes. We hypothesized that PFOS treatment interferes with lipid loss when switching from a high fat diet (HFD) to a standard diet (SD), and augments HFD-induced hepatic steatosis. Male C57BL/6 N mice were fed standard chow diet or 60% kCal high-fat diet (HFD) for 4 weeks to increase body weight. Then, some HFD mice were switched to SD and mice were further divided to diet only or diet containing 0.0003% PFOS, for six treatment groups: SD, HFD to SD (H-SD), HFD, SD + PFOS, H-SD + PFOS, or HFD + PFOS. After 10 weeks on study, blood and livers were collected. HFD for 14 weeks increased body weight and hepatic steatosis, whereas H-SD mice returned to SD measures. PFOS administration reduced body weight in mice fed a SD, but not H-SD or HFD. PFOS administration increased liver weight in H-SD + PFOS and HFD + PFOS mice. PFOS increased hepatic steatosis in H-SD and HFD groups. Hepatic mRNA expression and SWATH-MS proteomic analysis revealed that PFOS induced lipid and xenobiotic transporters, as well as metabolism pathways. Overall, the findings herein suggest that PFOS treatment did interfere with lipid loss associated with switch to a SD and similarly augmented hepatic lipid accumulation in mice established on an HFD.

Risk to human health related to the presence of perfluoroalkyl substances in food

The European Commission asked EFSA for a scientific evaluation on the risks to human health related to the presence of perfluoroalkyl substances (PFASs) in food. Based on several similar effects in animals, toxicokinetics and observed concentrations in human blood, the CONTAM Panel decided to perform the assessment for the sum of four PFASs: PFOA, PFNA, PFHxS and PFOS. These made up half of the lower bound (LB) exposure to those PFASs with available occurrence data, the remaining contribution being primarily from PFASs with short half-lives. Equal potencies were assumed for the four PFASs included in the assessment. The mean LB exposure in adolescents and adult age groups ranged from 3 to 22, the 95th percentile from 9 to 70 ng/kg body weight (bw) per week. Toddlers and 'other children' showed a twofold higher exposure. Upper bound exposure was 4- to 49-fold higher than LB levels, but the latter were considered more reliable. 'Fish meat', 'Fruit and fruit products' and 'Eggs and egg products' contributed most to the exposure. Based on available studies in animals and humans, effects on the immune system were considered the most critical for the risk assessment. From a human study, a lowest BMDL 10 of 17.5 ng/mL for the sum of the four PFASs in serum was identified for 1-year-old children. Using PBPK modelling, this serum level of 17.5 ng/mL in children was estimated to correspond to long-term maternal exposure of 0.63 ng/kg bw per day. Since accumulation over time is important, a tolerable weekly intake (TWI) of 4.4 ng/kg bw per week was established. This TWI also protects against other potential adverse effects observed in humans. Based on the estimated LB exposure, but also reported serum levels, the CONTAM Panel concluded that parts of the European population exceed this TWI, which is of concern.

Associations of Exposure to Perfluoroalkyl Substances With Thyroid Hormone Concentrations and Birth Size

BACKGROUND

Adequate thyroid function during pregnancy is essential for optimal fetal growth. Gestational exposure to perfluoroalkyl substances (PFAS) can negatively affect birth size and disrupt maternal and neonatal thyroid function, although the interrelationship is unclear.

OBJECTIVE

We aimed to quantify the associations between maternal serum-PFAS concentrations and birth weight, birth length, and cranial circumference. We also aimed to estimate associations between PFAS and thyroid hormone (TH) concentrations, thereby elucidating whether THs potentially mediate the associations between PFAS concentrations and birth size.

METHODS

We studied a population-based prospective cohort of 172 mother-singleton pairs from the Faroe Islands. Twelve PFAS were measured in maternal serum obtained at 34 weeks of gestation. THs were measured in maternal and cord serum. Associations between PFAS concentrations and birth size and TH concentrations were estimated using multivariable linear regressions. Sex-stratified analyses along with a mediation analysis were performed to estimate potential mediating effects of THs in the association between PFAS and birth outcomes.

RESULTS

Several PFASs were negatively associated with birth weight, length, and head circumference, and a general positive association between maternal serum-PFASs and cord serum-thyroid-stimulating hormone (TSH; also known as thyrotropin) was found. For instance, a doubling in perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) was associated with a 53% (95% CI, 18%-99%) and 40% (95% CI, 8%-81%) increases in TSH concentrations, respectively. There was little evidence of sexually dimorphic associations. Overall, THs were not found to mediate associations between PFASs and birth size.

CONCLUSION

In this study, several PFASs were negatively associated with birth size and increased THs; however, this did not explain lower birth weight among children exposed to PFAS.

Early Life Exposures to Perfluoroalkyl Substances in Relation to Adipokine Hormone Levels at Birth and During Childhood

BACKGROUND

Birth cohort studies have linked exposure to perfluoroalkyl substances (PFASs) with child anthropometry. Metabolic hormone dysregulation needs to be considered as a potential adverse outcome pathway. We examined the associations between PFAS exposures and concentrations of adipokine hormones from birth to adolescence.

METHODS

We studied 80 mother-child pairs from a Faroese cohort born in 1997 to 2000. Five PFASs were measured in maternal pregnancy serum and in child serum at ages 5, 7, and 13 years. Leptin, adiponectin, and resistin were analyzed in cord serum and child serum at the same ages. We fitted multivariable-adjusted generalized estimating equations to assess the associations of PFASs at each age with repeated adipokine concentrations at concurrent and subsequent ages.

RESULTS

We observed tendencies of inverse associations between PFASs and adipokine hormones specific to particular ages and sex. Significant associations with all adipokines were observed for maternal and child 5-year serum PFAS concentrations, whereas associations for PFASs measured at ages 7 to 13 years were mostly null. The inverse associations with leptin and adiponectin were seen mainly in females, whereas the inverse PFAS associations with resistin levels were seen mainly in males. Estimates for significant associations (P value <0.05) suggested mean decreases in hormone levels (range) by 38% to 89% for leptin, 16% to 70% for adiponectin, and 33% to 62% for resistin for each twofold increase in serum PFAS concentration.

CONCLUSIONS

These findings suggest adipokine hormone dysregulation in early life as a potential pathway underlying PFAS-related health outcomes and underscore the need to further account for susceptibility windows and sex-dimorphic effects in future investigations.