Efficiency of maternal-fetal transfer of perfluoroalkyl and polyfluoroalkyl substances

Maternal transfer of per- and polyfluoroalkyl substances (PFAS) in wild birds: A systematic review and meta-analysis

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals widely used in consumer products. PFAS can accumulate in animal tissues, resulting in biomagnification and adverse effects on wildlife, such as reproductive impairment. In bird species, PFAS are transferred from mothers to eggs along with essential nutrients and may affect embryo development. However, the extent of maternal PFAS transfer across different species and compounds remains poorly understood. Here, we conducted a systematic review and meta-analysis to quantify maternal PFAS transfer in wild birds and investigate potential sources of variation. We tested the moderating effects of compounds' physicochemical properties and biological traits of studied birds. The dataset included 505 measurements of PFAS concentration and 371 effect sizes derived from 13 studies on 16 bird species and 25 compounds. Overall, across all studies and species, we found a 41% higher concentration of PFAS in offspring than in mothers. Specifically, contaminants were concentrated in the yolk, longer and heavier compounds showed preferential transfer, larger clutch size was associated with decreased PFAS transfer and a higher transfer rate was shown in species with piscivorous and opportunistic/diverse diets. A validation assessment showed good robustness of the overall meta-analytic result. Given the crucial role of birds in maintaining ecological balance, this research article has relevant implications for modelling the impacts of PFAS on wildlife, ecosystems, and human health.

Engineering human midbrain organoid microphysiological systems to model prenatal PFOS exposure

Perfluorooctane sulfonate (PFOS), a class of synthetic chemicals detected in various environmental compartments, has been associated with dysfunctions of the human central nervous system (CNS). However, the underlying neurotoxicology of PFOS exposure is largely understudied due to the lack of relevant human models. Here, we report bioengineered human midbrain organoid microphysiological systems (hMO-MPSs) to recapitulate the response of a fetal human brain to multiple concurrent PFOS exposure conditions. Each hMO-MPS consists of an hMO on a fully 3D printed holder device with a perfusable organoid adhesion layer for enhancing air-liquid interface culturing. Leveraging the unique, simply-fabricated holder devices, hMO-MPSs are scalable, easy to use, and compatible with conventional well-plates, and allow easy transfer onto a multiple-electrode array (MEA) system for plug-and-play measurement of neural activity. Interestingly, the neural activity of hMO-MPSs initially increased and subsequently decreased by exposure to a concentration range of 0, 30, 100, to 300 μM of PFOS. Furthermore, PFOS exposure impaired neural development and promoted neuroinflammation in the engineered hMO-MPSs. Along with PFOS, our platform is broadly applicable for studies toxicology of various other environmental pollutants.

There's Something in What We Eat: An Overview on the Extraction Techniques and Chromatographic Analysis for PFAS Identification in Agri-Food Products

Per- and polyfluorinated alkyl substances (PFASs) are a group of anthropogenic chemicals used in a range of industrial processes and consumer products. Recently, their ubiquitous presence in the environment as well as their toxicological effects in humans have gained relevant attention. Although the occurrence of PFASs is widely investigated in scientific community, the standardization of analytical method for all matrices still remains an important issue. In this review, we discussed extraction and detection methods in depth to evaluate the best procedures of PFAS identification in terms of analytical parameters (e.g., limits of detection (LODs), limits of quantification (LOQs), recoveries). Extraction approaches based on liquid-liquid extraction (LLE), alkaline digestion, and solid phase extraction (SPE), followed by liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) analysis are the main analytical methods applied in the literature. The results showed detectable recoveries of PFOA and PFOS in meat, milk, vegetables, eggs products (90.6-101.2% and of 89.2-98.4%), and fish (96-108%). Furthermore, the low LOD and LOQ values obtained for meat (0.00592-0.01907 ng g-1; 0.050 ng g-1), milk (0.003-0.009 ng g-1; 0.010-0.027 ng g-1), fruit (0.002-0.009 ng g-1; 0.006-0.024 ng g-1), and fish (0.00369-0.017.33 ng g-1; 0.05 ng g-1) also confirmed the effectiveness of the recent quick, easy, cheap, effective, rugged, and safe method (QuEChERS) for simple, speedy, and sensitive ultra-trace PFAS analysis.

Profiles and transplacental transfer of per- and polyfluoroalkyl substances in maternal and umbilical cord blood: A birth cohort study in Zhoushan, Zhejiang Province, China

Per- and polyfluoroalkyl substances (PFAS) can pass through the placental barrier and pose health risks to fetuses. However, exposure and transplacental transfer patterns of emerging PFAS remain unclear. Here, 24 PFAS were measured in paired maternal whole blood (n = 228), umbilical cord whole blood (n = 119) and serum (n = 120). Orthogonal partial least-squares discriminant analysis (OPLS-DA) was used to differentiate PFAS between different matrices. The transplacental transfer (TPT) of PFAS was calculated using cord to maternal whole blood concentration ratios. PFOS and PFOA were still the dominant PFAS in maternal samples. The emerging PFAS had higher TPT than PFOS and PFOA. Moreover, PFAS with the same chain length but different functional groups and C-F bonds showed different TPT, such as PFOS and PFOSA (C8, median: 0.090 vs. 0.305, p < 0.05) and PFHxS and 4:2 FTS (C6, median: 0.220 vs. 1.190, p < 0.05). A significant sex difference in 4:2 FTS (median: boys 1.250, girls 1.010, p < 0.05) were found. Furthermore, we observed a significant U-shaped trend for the TPT of carboxylates with increasing carbon chain length. PFAS showed a compound-specific transfer through placental barrier and a compound-specific distribution between different matrices in this study.

Profile of per- and polyfluoroalkyl substances, source appointment, and determinants in Argentinean postpartum women

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic chemicals with potential adverse health effects. Information concerning PFAS concentrations in relation to pregnancy is scarce in South America and non-existent in Argentina.

AIM

We aimed to investigate an extended maternal PFAS profile herein serum concentrations in a regional and global view, source appointment, and determinants in Argentinean women.

METHODS

A cross-sectional study with a sampling period from 2011 to 2012 included 689 women from Ushuaia and Salta in Argentina. Serum samples collected two days postpartum were analyzed by ultra-high pressure liquid chromatography coupled to electrospray negative ionisation tandem-quadrupole mass-spectrometry. Principal Component Analysis (PCA) following absolute principal component score-multiple linear regression (APCS-MLR) was used for PFAS source appointments. Determinants of PFAS were explored through a MLR approach. A review of previous studies within the same period was conducted to compare with present levels.

RESULTS

Argentinean PFAS concentrations were the lowest worldwide, with PFOS (0.74 ng/mL) and PFOA (0.11 ng/mL) as the dominant substances. Detection frequencies largely aligned with the compared studies, indicating the worldwide PFAS distribution considering the restrictions. The PCA revealed region-specific loading patterns of two component groups of PFAS, a mixture of replaced and legacy substances in Ushuaia and long-chain in Salta. This might relate to a mix of non-diet and diet exposure in Ushuaia and diet in Salta. Region, age, lactation, parity, household members, migration, bottled water, and freshwater fish were among the determinants of various PFAS.

CONCLUSION

This is the first study to monitor human PFAS exposure in Argentina. Maternal PFAS concentrations were the lowest observed worldwide in the same period. Exposure contributions are suggested to be affected by restrictions and substitutions. Given the limited population-based studies and the emergence of PFAS, it is essential to conduct further monitoring of PFAS in Argentina and South America.

Changes in Concentrations of Polyfluoroalkyl Substances in Human Milk Over Lactation Time and Effects of Maternal Exposure via Analysis of Matched Samples

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are potentially related to many adverse health outcomes and could be transferred from maternal blood to human milk, which is an important exposure source for infants during a long-term period. In this study, the maternal blood of 76 women after delivery and their matched human milk samples obtained at 0.5, 1, and 3 months were analyzed by solid-phase extraction method with metal-organic framework/polymer hybrid nanofibers as the sorbents and ultrahigh-performance liquid chromatography-negative electrospray ionization mass spectrometric for quantitative analysis of 31 PFAS. The perfluorooctanoic acid, perfluorooctane sulfonate, and N-methyl perfluorooctane sulfonamido acetic acid (N-MeFOSAA) contributed to more than approximately 50% of the total PFAS concentrations in blood and human milk, while N-MeFOSAA (median: 0.274 ng/mL) was the highest PFAS in human milk at 3 months. The transfer efficiencies for PFAS from maternal blood to human milk at 0.5 months were generally lower, with medians ranging from 0.20% to 16.9%. The number of PFAS species detected in human milk increased as the lactation time went on from 0.5 to 3 months, and the concentrations of 10 PFAS displayed an increasing trend as the prolongation of lactation time (p < 0.05).

Effect modification by maternal vitamin D status in the association between prenatal exposure to per- and polyfluoroalkyl substances and neurodevelopment in 2-year-old children

BACKGROUND

Pregnant women in the Shanghai Birth Cohort (SBC) of China faced dual threats of per- and polyfluoroalkyl substances (PFAS) exposure and vitamin D (VD) insufficiency, potentially impacting offspring neurodevelopment. However, little is known about whether maternal VD status modifies PFAS-related neurodevelopment effect.

OBJECTIVES

To explore the modifying role of maternal VD status in the effect of prenatal PFAS exposure on childhood neurodevelopment.

METHODS

We included 746 mother-child pairs from the SBC. Ten PFAS congeners and VD levels were measured in maternal blood samples collected during the first and second trimester respectively. At 2 years of age, toddlers underwent neurodevelopment assessments using Bayley-III Scales. Multivariate linear, logistic regression, and weighted quantile sum approach were used to estimate associations of Bayley-III scores with individual and mixture PFAS. We stratified participants into VD sufficient and insufficient groups and further balanced PFAS differences between these groups by matching all PFAS levels. We fitted the same statistical models in each VD group before and after matching.

RESULTS

Nearly half (46.5 %) of pregnant women were VD insufficient (<30 ng/mL). In the overall population, PFAS exposure was associated with lower language scores and an increased risk for neurodevelopmental delay, but higher cognitive scores. However, adverse associations with PFAS were mainly observed in the VD sufficient group, while the VD insufficient group showed positive cognitive score associations. Higher PFAS concentrations were found in the VD sufficient group compared to the VD insufficient group. Post-matching, adverse associations in the VD sufficient group were nullified, whereas in the VD insufficient group, positive associations disappeared and adverse associations becoming more pronounced.

CONCLUSION

In this Chinese birth cohort, high prenatal PFAS exposure and low maternal VD levels collectively heighten the risk of adverse childhood neurodevelopment. However, disentangling PFAS and VD interrelationships is crucial to avoid paradoxical findings.

Assessment of Fetal Exposure and Elimination of Perfluoroalkyl and Polyfluoroalkyl Substances: New Evidence from Paired Serum, Placenta, and Meconium Samples

Multiple pieces of evidence have shown that prenatal exposure to perfluoroalkyl and polyfluoroalkyl substances (PFASs) is closely related to adverse birth outcomes for infants. However, difficult access to human samples limits our understanding of PFASs transport and metabolism across the human placental barrier, as well as the accurate assessment of fetal PFASs exposure. Herein, we assess fetal exposure to 28 PFASs based on paired serum, placenta, and meconium samples. Overall, 21 PFASs were identified first to be exposed to the fetus prenatally and to be metabolized and excreted by the fetus. In meconium samples, 25 PFASs were detected, with perfluorooctane sulfonate and perfluorohexane sulfonic acid being the dominant congeners, suggesting the metabolism and excretion of PFASs through meconium. Perfluoroalkyl sulfonic acids might be more easily eliminated through the meconium than perfluorinated carboxylic acids. Importantly, based on molecular docking, MRP1, OATP2B1, ASCT1, and P-gp were identified as crucial transporters in the dynamic placental transfer of PFASs between the mother and the fetus. ATSC5p and PubchemFP679 were recognized as critical structural features that affect the metabolism and secretion of PFASs through meconium. With increasing carbon chain length, both the transplacental transfer efficiency and meconium excretion efficiency of PFASs showed a structure-dependent manner. This study reports, for the first time, that meconium, which is a noninvasive and stable biological matrix, can be strong evidence of prenatal PFASs exposure.

Exposure to perfluoroalkyl and polyfluoroalkyl substances and pediatric obesity: a systematic review and meta-analysis

INTRODUCTION

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are potentially obesogenic for children. We undertook a systematic review to synthesize this literature and explore sources of heterogeneity in previously published epidemiological studies.

METHODS

Studies that collected individual-level PFAS and anthropometric data from children up to 12 years of age were identified by searching six databases. We excluded studies that only evaluated obesity measures at the time of birth. A full-text review and quality assessment of the studies was performed using the Office of Health Assessment and Translation (OHAT) criteria. Forest plots were created to summarize measures of association and assess heterogeneity across studies by chemical type and exposure timing. Funnel plots were used to assess small-study effects.

RESULTS

We identified 24 studies, of which 19 used a cohort design. There were 13 studies included in the meta-analysis examining various chemicals and outcomes. Overall prenatal exposures to four different types of PFAS were not statistically associated with changes in body mass index (BMI) or waist circumference. In contrast, for three chemicals, postnatal exposures were inversely related to changes in BMI (i.e., per log10 increase in PFOS: BMI z-score of -0.16 (95% CI: -0.22, -0.10)). There was no substantial heterogeneity in the reported measures of association within prenatal and postnatal subgroups. We observed modest small-study effects, but correction for these effects using the Trim and Fill method did not change our summary estimate(s).

CONCLUSION

Our review found no evidence of a positive association between prenatal PFAS exposure and pediatric obesity, whereas an inverse association was found for postnatal exposure. These findings should be interpreted cautiously due to the small number of studies. Future research that can inform on the effects of exposure mixtures, the timing of the exposure, outcome measures, and the shape of the exposure-response curve is needed.

Association of prenatal exposure to perfluorinated and polyfluoroalkyl substances with childhood neurodevelopment: A systematic review and meta-analysis

BACKGROUND

Although previous studies have shown an association between prenatal exposure to perfluorinated and polyfluoroalkyl substances (PFAS) and neurodevelopmental disorders in children, the results have been inconsistent. We summarize studies on the association between prenatal PFAS exposure and neurodevelopment in children in order to better understand the relationship.

OBJECTIVE

We conducted a meta-analysis of prenatal PFAS exposure and developmental outcomes associated with intellectual, executive function and behavioral difficulty in children to explore the relationship between prenatal exposure to perfluorinated and polyfluoroalkyl substances (PFAS) and neurodevelopmental disorders in children.

METHODS

We searched for articles published up to August 3, 2023, included and quantified original studies on PFAS and child Intelligence Quotient (IQ), executive function and behavioral difficulty during pregnancy, and systematically summarized articles that could not be quantified.

CONCLUSION

There is evidence of sex-specific relationship between PFAS exposure and children's PIQ. We found that PFOS [β = -1.56, 95% CI = -2.96, - 0.07; exposure = per 1 ln (ng/ml) increase], PFOA [β = -1.87, 95% CI = -3.29, - 0.46; exposure = per 1 ln (ng/ml) increase], PFHxS [β = -2.02, 95% CI = -3.23, - 0.81; exposure = per 1 ln (ng/ml) increase] decreased performance IQ in boys, but PFOS [β = 1.56, 95% CI = 0.06, 3.06; exposure = per 1 ln (ng/ml) increase] increased performance IQ in girls. PFAS are associated with executive function impairments in children, but not related to behavioral difficulty in children.

Prenatal per- and polyfluoroalkyl substances exposure and gut microbiota of infants: A prospective cohort study

Prenatal exposure to per- and polyfluoroalkyl substances (PFASs) has been reported to be linked to a series of adverse health outcomes in mothers and their children. As the gut microbiota is a sensitive biomarker for assessing the toxicity of environmental contaminants, this study attempted to investigate whether prenatal PFASs exposure was associated with the gut microbiota of infants. Based on the Shanghai-Minhang Birth Cohort Study, this prospective cohort study included 69 mother-infant pairs. Fasting blood samples were collected from pregnant women for the PFASs assay. We collected fecal samples of infants at 1 year of age and analyzed the V3-V4 hypervariable region of the bacterial 16 S rRNA gene by high-throughput sequencing. Among the detected 11 PFASs, the concentration of perfluorooctanoic acid (22.19 ng/mL) was the highest, followed by perfluorooctane sulfonic acid (12.08 ng/mL). Compared with infants whose mothers' total PFASs concentrations during pregnancy were at the 40th percentile or lower (reference group), the species richness and diversity of microbiota were lower in infants prenatally exposed to a high level of PFASs (the sum of PFASs concentrations above the 60th percentile). Prenatal exposure to PFASs was associated with a higher proportion of Acidaminococcaceae, Acidaminococcus, Megamonas, Megasphaera micronuciformis and Megamonas funiformis in infants. The changes of the species have been suggested to be associated with immune and metabolic dysfunction in humans. Functional alterations of gut microbiota due to PFASs exposure were dominated by an enrichment of butanoate metabolism. Our preliminary findings may shed light on the potential role of the microbiota underlying the well-known impact of prenatal PFASs exposure on health outcomes of humans in later life.

Association of adverse fetal outcomes with placental inflammation after oral gestational exposure to hexafluoropropylene oxide dimer acid (GenX) in Sprague-Dawley rats

Hexafluoropropylene oxide dimer acid (HFPO-DA), known as "GenX" for its trade name, is gradually taking the place of Perfluorooctanoic acid (PFOA). However, there is a poor understanding of the developmental effects of GenX. This study aims to explore whether GenX produces adverse effects on offspring development in Sprague-Dawley (SD) rats and the underlying mechanisms. Pregnant rats were orally administered with GenX (0, 1, 10 and 100 mg/kg/day) from gestational 0.5-19.5 days. Experimental data showed that the exposure to GenX resulted in increased rats' gestational weight gain, whereas both body weight and body length of their fetuses born naturally were significantly reduced. This could contribute to the developmental delays of fetal body weight, body length and tail length from postnatal 1-21 days. Histopathological evaluation of placenta indicated that GenX exposure led to neutrophil infiltration in decidual zone and congestion in labyrinth zone. Moreover, placental proteomics showed changes at the expression levels of the inflammation-related proteins in the Rap1 signaling pathway. In conclusion, gestational exposure to GenX induced fetal intrauterine and extrauterine development retardation in SD rats. Placental inflammation may play a key role in this process through the Rap1 signaling pathway.

Prenatal exposure to Per- and polyfluoroalkyl substances and adiposity measures of children at 4 and 6 years: A prospective birth cohort in China

There is growing evidence that prenatal exposure to Per- and polyfluoroalkyl substances (PFAS) was associated with childhood obesity, but evidence on multiple adiposity measures including arm circumference (AC), and waist circumference (WC) among Chinese children is limited. We investigated the associations of prenatal exposure to PFAS with adiposity measures of children at 4 and 6 years of age in the Shanghai-Minhang Birth Cohort Study. A total of 573 mother-child pairs with maternal PFAS concentrations and at least one measurement of adiposity measures of children were included in the present study. Eleven PFAS were assessed in maternal fasting blood samples. Information on children's weight, height, AC, and WC was collected at follow-ups. Weight for age Z score (WAZ), body mass index for age Z score (BMIz), and children overweight were calculated based on the World Health Organization Child Growth Standards. Multivariate linear regression, Poisson regression with robust error variance, and Bayesian Kernel Machine Regression (BKMR) models were used to examine the associations of prenatal exposure to PFAS with children's adiposity measures. Eight PFAS with detection rates above 85 % were included in the analyses. In the multivariate linear regression models, maternal PFNA concentrations were associated with a greater AC (β = 0.29, 95 % Confidence Interval (CI): 0.04-0.55) in 4-year-old children and with an increase in WAZ (β = 0.26, 95 % CI: 0.06-0.46), BMIz (β = 0.31, 95 % CI: 0.09-0.53), AC (β = 0.49, 95 % CI: 0.08-0.90), and WC (β = 1.47, 95 % CI: 0.41-2.52) in 6-year-old children. We also observed the associations of maternal concentrations of PFOS, PFNA, PFUdA, and PFTrDA with the increased risk of children overweight in 6-year-old children. BKMR models further supported the findings from multivariate linear regression and Poisson regression models, and identified PFNA as the most important contributor. Moreover, the associations described above were generally more pronounced in girls. In conclusion, prenatal exposure to PFAS was associated with an increased risk of children's adiposity with a sex-specific manner, and PFNA contributed most to the associations after controlling for the effect of co-exposure to other PFAS compounds, especially among girls at 6 years of age.

Prenatal Exposure to Perfluoroalkyl Substances and Child Behavior at Age 12: A PELAGIE Mother-Child Cohort Study

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are chemical substances spread throughout the environment worldwide. Exposure during pregnancy represents a specific window of vulnerability for child health.

OBJECTIVE

Our objective was to assess the impact of prenatal exposure to multiple PFAS on emotional and behavioral functions in 12-y-old children.

METHOD

In the PELAGIE mother-child cohort (France), prenatal exposure to nine PFAS was measured from concentrations in cord serum samples. Behavior was assessed at age 12 y using the parent-reported Strengths and Difficulties Questionnaire (SDQ) and the self-reported Dominic Interactive for Adolescents (DIA) for 444 children. Associations were estimated using negative binomial models for each PFAS. Bayesian kernel machine regression (BKMR) models were performed to assess the exposure mixture effect on children's behavior.

RESULTS

In our study population, 73% of mothers had spent more than 12 y in education. Higher scores on SDQ externalizing subscale were observed with increasing cord-serum concentration of perfluorooctanoic acid (PFOA) and perfluorononanoic acid (PFNA) [adjusted mean ratio ( aMR ) = 1.18 , 95% confidence interval (CI): 1.03, 1.34, and aMR = 1.14 (95% CI: 1.00, 1.29) for every doubling of concentration, respectively]. Results for the hyperactivity score were similar [aMR = 1.20 (95% CI: 1.04, 1.40) and aMR = 1.18 (95% CI: 1.02, 1.36), respectively]. With regard to major depressive disorder and internalizing subscales, perfluorodecanoic acid (PFDA) was associated with higher self-reported DIA scores [aMR = 1.14 (95% CI: 1.01, 1.27) and aMR = 1.11 (95% CI: 1.02, 1.21), respectively]. In terms of the anxiety subscale, PFDA and PFNA were associated with higher scores [aMR = 1.11 (95% CI: 1.02, 1.21) and aMR = 1.10 (95% CI: 1.01, 1.19), respectively]. Concurrent increases in the PFAS concentrations included in the BKMR models showed no change in the SDQ externalizing and DIA internalizing subscales scores.

CONCLUSION

Prenatal exposure to PFNA and PFOA were associated with increasing scores for measures of externalizing behaviors, specifically hyperactivity. We also identified associations between PFNA and PFDA prenatal exposure levels and increasing scores related to internalizing behaviors (general anxiety and major depressive disorder), which adds to the as yet sparse literature examining the links between prenatal exposure to PFAS and internalizing disorders. https://doi.org/10.1289/EHP12540.

Exposure to per- and polyfluoroalkyl substances in women with twin pregnancies: Patterns and variability, transplacental transfer, and predictors

The extensive exposure to per- and polyfluoroalkyl substances (PFASs) has raised public health concerns. The issue of PFAS exposures in women with twin pregnancies remains unresolved. To determine exposure profiles, the transplacental transfer efficiencies (TTEs) of PFASs and predictors were estimated. We found that serum PFASs were widely detected, with detection rates of over 50% for 12 PFASs in maternal serum throughout pregnancy. The majority of PFAS levels exhibited fair to good reproducibility (ICCs > 0.40). Moderate to low correlations were observed for most PFASs between twin cord serum and maternal serum at three trimesters (rs = 0.13-0.77, p values < 0.01). We first presented a U-shaped trend for TTEs with increasing chain length for perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs) in twins, even in twin sex subgroups. Further, we found that PC4 and PC5 (indicators of exposure to PFHxS and 6:2 Cl-PFESA) were positively associated with age (β = 0.85, 1.30, and 1.36, respectively). Our findings suggested that there is moderate variability among certain PFASs and that these PFASs have the ability to cross the placental barrier. Exposure patterns were found to be associated with maternal age.

Fluorine Mass Balance, including Total Fluorine, Extractable Organic Fluorine, Oxidizable Precursors, and Target Per- and Polyfluoroalkyl Substances, in Pooled Human Serum from the Tromsø Population in 1986, 2007, and 2015

Of the thousands of per- and polyfluoroalkyl substances (PFAS) known to exist, only a small fraction (≤1%) are commonly monitored in humans. This discrepancy has led to concerns that human exposure may be underestimated. Here, we address this problem by applying a comprehensive fluorine mass balance (FMB) approach, including total fluorine (TF), extractable organic fluorine (EOF), total oxidizable precursors (TOP), and selected target PFAS, to human serum samples collected over a period of 28 years (1986, 2007, and 2015) in Tromsø, Norway. While concentrations of TF did not change between sampling years, EOF was significantly higher in 1986 compared to 2007 and 2015. The ∑12PFAS concentrations were highest in 2007 compared to 1986 and 2015, and unidentified EOF (UEOF) decreased from 1986 (46%) to 2007 (10%) and then increased in 2015 (37%). While TF and EOF were not influenced by sex, women had higher UEOF compared to men, opposite to target PFAS. This is the first FMB in human serum to include TOP, and it suggests that precursors with >4 perfluorinated carbon atoms make a minor contribution to EOF (0-4%). Additional tools are therefore needed to identify substances contributing to the UEOF in human serum.

Per- and polyfluoroalkyl substances (PFAS) and thyroid hormone measurements in dried blood spots and neonatal characteristics: a pilot study

BACKGROUND

Pediatric thyroid diseases have been increasing in recent years. Environmental risk factors such as exposures to chemical contaminants may play a role but are largely unexplored. Archived neonatal dried blood spots (DBS) offer an innovative approach to investigate environmental exposures and effects.

OBJECTIVE

In this pilot study, we applied a new method for quantifying per- and polyfluoroalkyl substances (PFAS) to 18 archived DBS from babies born in California from 1985-2018 and acquired thyroid hormone measurements from newborn screening tests. Leveraging these novel data, we evaluated (1) changes in the concentrations of eight PFAS over time and (2) the relationship between PFAS concentrations, thyroid hormone concentrations, and neonatal characteristics to inform future research.

METHODS

PFAS concentrations in DBS were measured using ultra-high-performance liquid chromatography-mass spectrometry. Summary statistics and non-parametric Wilcoxon rank-sum and Kruskal-Wallis tests were used to evaluate temporal changes in PFAS concentrations and relationships between PFAS concentrations, thyroid hormone concentrations, and neonatal characteristics.

RESULTS

The concentration and detection frequencies of several PFAS (PFOA, PFOS, and PFOSA) declined over the assessment period. We observed that the timing of specimen collection in hours after birth was related to thyroid hormone but not PFAS concentrations, and that thyroid hormones were related to some PFAS concentrations (PFOA and PFOS).

IMPACT STATEMENT

This pilot study examines the relationship between concentrations of eight per- and polyfluoroalkyl substances (PFAS), thyroid hormone levels, and neonatal characteristics in newborn dried blood spots (DBS) collected over a period of 33 years. To our knowledge, 6 of the 22 PFAS we attempted to measure have not been quantified previously in neonatal DBS, and this is the first study to examine both PFAS and thyroid hormone concentrations using DBS. This research demonstrates the feasibility of using newborn DBS for quantifying PFAS exposures in population-based studies, highlights methodological considerations in the use of thyroid hormone data for future studies using newborn DBS, and indicates potential relationships between PFAS concentrations and thyroid hormones for follow-up in future research.

Early life exposure to low-dose perfluorooctane sulfonate disturbs gut barrier homeostasis and increases the risk of intestinal inflammation in offspring

Perfluorooctane sulfonate (PFOS), one of the legacy per- and poly-fluoroalkyl substances (PFAS), is associated with multiple adverse health effects on children. However, much remains to be known about its potential impacts on intestinal immune homeostasis during early life. Our study found that PFOS exposure during pregnancy in rats significantly increased the maternal serum levels of interleukin-6 (IL-6) and zonulin, a gut permeability biomarker, and decreased gene expressions of Tight junction protein 1 (Tjp1) and Claudin-4 (Cldn4), the tight junction proteins, in maternal colons on gestation day 20 (GD20). Being exposed to PFOS during pregnancy and lactation in rats significantly decreased the body weight of pups and increased the offspring's serum levels of IL-6 and tumor necrosis factor-α (TNF-α) on postnatal day 14 (PND14), and induced a disrupted gut tight junction, manifested by decreased expressions of Tjp1 in pup's colons on PND14 and increased pup's serum concentrations of zonulin on PND28. By integrating high-throughput 16S rRNA sequencing and metabolomics, we demonstrated that early-life PFOS exposure altered the diversity and composition of gut microbiota that were correlated with the changed metabolites in serum. The altered blood metabolome was associated with increased proinflammatory cytokines in offspring. These changes and correlations were divergent at each developmental stage, and pathways underlying immune homeostasis imbalance were significantly enriched in the PFOS-exposed gut. Our findings provide new evidence for the developmental toxicity of PFOS and its underlying mechanism and explain in part the epidemiological observation of its immunotoxicity.

Prenatal exposure to legacy PFAS and neurodevelopment in preschool-aged Canadian children: The MIREC cohort

BACKGROUND

Exposure to perfluoroalkyl substances (PFAS) has been shown to be neurotoxic in experimental studies, but epidemiological evidence linking prenatal PFAS exposure to child neurodevelopment is equivocal and scarce.

OBJECTIVE

To quantify associations between prenatal exposure to legacy PFAS and children's intelligence (IQ) and executive functioning (EF) in a Canadian pregnancy and birth cohort and to determine if these associations differ by child sex.

METHODS

We measured first-trimester plasma concentrations of perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), and perfluorohexanesulfonic acid (PFHxS) in the Maternal-Infant Research on Environmental Chemicals (MIREC) study and assessed children's full-scale (n = 522), performance (n = 517), and verbal (n = 519) IQ using the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-III). Children's working memory (n = 513) and ability to plan and organize (n = 514) were assessed using a parent-reported questionnaire, the Behavior Rating Inventory of Executive Function - Preschool Version (BRIEF-P). We quantified associations between individual log2-transformed PFAS exposure and children's IQ and EF using multiple linear regression analyses and evaluated effect modification by child sex. We also used Repeated Holdout Weighted Quantile Sum (WQS) regression models with effect modification by child sex to quantify the effect of combined exposure to all three PFAS chemicals on IQ and EF. All models were adjusted for key sociodemographic characteristics.

RESULTS

Geometric mean plasma concentrations (IQR) for PFOA, PFOS and PFHxS were 1.68 (1.10-2.50), 4.97 (3.20-6.20) and 1.09 (0.67-1.60) μg/L respectively. We found evidence of effect modification by child sex in all models examining performance IQ (p < .01). Specifically, every doubling of PFOA, PFOS, and or PFHxS was inversely associated with performance IQ, but only in males (PFOA: B = -2.80, 95% CI: -4.92, -0.68; PFOS: B = -2.64, 95% CI: -4.77, -0.52; PFHxS: B = -2.92, 95% CI: -4.72, -1.12). Similarly, every quartile increase in the WQS index was associated with poorer performance IQ in males (B = -3.16, 95% CI: -4.90, -1.43), with PFHxS contributing the largest weight to the index. In contrast, no significant association was found for females (B = 0.63, 95% CI: -0.99, 2.26). No significant associations were found for EF in either males or females.

CONCLUSIONS

Higher prenatal PFAS exposure was associated with lower performance IQ in males, suggesting that this association may be sex- and domain-specific.

Newborn metabolomic signatures of maternal per- and polyfluoroalkyl substance exposure and reduced length of gestation

Marginalized populations experience disproportionate rates of preterm birth and early term birth. Exposure to per- and polyfluoroalkyl substances (PFAS) has been reported to reduce length of gestation, but the underlying mechanisms are unknown. In the present study, we characterized the molecular signatures of prenatal PFAS exposure and gestational age at birth outcomes in the newborn dried blood spot metabolome among 267 African American dyads in Atlanta, Georgia between 2016 and 2020. Pregnant people with higher serum perfluorooctanoic acid and perfluorohexane sulfonic acid concentrations had increased odds of an early birth. After false discovery rate correction, the effect of prenatal PFAS exposure on reduced length of gestation was associated with 8 metabolomic pathways and 52 metabolites in newborn dried blood spots, which suggested perturbed tissue neogenesis, neuroendocrine function, and redox homeostasis. These mechanisms explain how prenatal PFAS exposure gives rise to the leading cause of infant death in the United States.

Nutrition paves the way to environmental toxicants and influences fetal development during pregnancy

Nutrition plays a major role in the healthy pregnancy and development of the fetus. In addition, nutrition can expose humans to a wide range of potentially hazardous environmental constituents, such as organic pollutants and heavy metals from marine or agricultural food products while processing, producing, and packaging. Humans constantly face these constituents through air, water, soil, food, and domestic products. During pregnancy, the rate of cellular division and differentiation is higher; exposure to any of these environmental toxicants can lead to developmental defects as they cross the placental barrier and, in some cases, can harm the successive generation too, as some contaminants can act on the reproductive cells of the fetus (Diethylstilbestrol). Pregnant women are considered a vulnerable population to food contaminant exposure and require a proper dietary chart and conscious food choices. Food is a source of both essential nutrients and environmental toxicants. Here, we have researched the possible toxicants of the food industry and their influence on the fetus's in-utero development, along with the importance of dietary interventions and the need to balance a healthy diet to overcome the harms. The cumulative exposure to environmental toxicants can influence the mother's prenatal environment and affect the fetus's development.

Determinants of maternal and neonatal PFAS concentrations: a review

Per- and polyfluoroalkyl substances (PFAS) are used for their properties such as stain and water resistance. The substances have been associated with adverse health outcomes in both pregnant mothers and infants, including pre-eclampsia and low birthweight. A growing body of research suggests that PFAS are transferred from mother to fetus through the placenta, leading to in utero exposure. A systematic review was performed using the PubMed database to search for studies evaluating determinants of PFAS concentrations in blood matrices of pregnant mothers and neonates shortly after birth. Studies were included in this review if an observational study design was utilized, exposure to at least one PFAS analyte was measured, PFAS were measured in maternal or neonatal matrices, at least one determinant of PFAS concentrations was assessed, and results such as beta estimates were provided. We identified 35 studies for inclusion in the review and evaluated the PFAS and determinant relationships among the factors collected in these studies. Parity, breastfeeding history, maternal race and country of origin, and household income had the strongest and most consistent evidence to support their roles as determinants of certain PFAS concentrations in pregnant mothers. Reported study findings on smoking status, alcohol consumption, and pre-pregnancy body mass index (BMI) suggest that these factors are not important determinants of PFAS concentrations in pregnant mothers or neonates. Further study into informative factors such as consumer product use, detailed dietary information, and consumed water sources as potential determinants of maternal or neonatal PFAS concentrations is needed. Research on determinants of maternal or neonatal PFAS concentrations is critical to estimate past PFAS exposure, build improved exposure models, and further our understanding on dose-response relationships, which can influence epidemiological studies and risk assessment evaluations. Given the potential for adverse outcomes in pregnant mothers and neonates exposed to PFAS, it is important to identify and understand determinants of maternal and neonatal PFAS concentrations to better implement public health interventions in these populations.

Evaluation of Per- and Polyfluoroalkyl Substances (PFAS) In Vitro Toxicity Testing for Developmental Neurotoxicity

Per- and polyfluoroalkyl substances (PFAS) are a diverse set of commercial chemicals widely detected in humans and the environment. However, only a limited number of PFAS are associated with epidemiological or experimental data for hazard identification. To provide developmental neurotoxicity (DNT) hazard information, the work herein employed DNT new approach methods (NAMs) to generate in vitro screening data for a set of 160 PFAS. The DNT NAMs battery was comprised of the microelectrode array neuronal network formation assay (NFA) and high-content imaging (HCI) assays to evaluate proliferation, apoptosis, and neurite outgrowth. The majority of PFAS (118/160) were inactive or equivocal in the DNT NAMs, leaving 42 active PFAS that decreased measures of neural network connectivity and neurite length. Analytical quality control indicated 43/118 inactive PFAS samples and 10/42 active PFAS samples were degraded; as such, careful interpretation is required as some negatives may have been due to loss of the parent PFAS, and some actives may have resulted from a mixture of parent and/or degradants of PFAS. PFAS containing a perfluorinated carbon (C) chain length ≥8, a high C:fluorine ratio, or a carboxylic acid moiety were more likely to be bioactive in the DNT NAMs. Of the PFAS positives in DNT NAMs, 85% were also active in other EPA ToxCast assays, whereas 79% of PFAS inactives in the DNT NAMs were active in other assays. These data demonstrate that a subset of PFAS perturb neurodevelopmental processes in vitro and suggest focusing future studies of DNT on PFAS with certain structural feature descriptors.

Cross-sectional associations of maternal PFAS exposure on SARS-CoV-2 IgG antibody levels during pregnancy

BACKGROUND

Perfluoroalkylated substances (PFAS) are man-made, persistent organic compounds with immune-modulating potentials. Given that pregnancy itself represents an altered state of immunity, PFAS exposure-related immunotoxicity is an important environmental factor to consider in SARS-CoV-2 infection during pregnancy as it may further affect humoral immune responses.

AIM

To investigate the relationship between maternal plasma PFAS concentrations and SARS-CoV-2 antibody levels in a NYC-based pregnancy cohort.

METHODS

Maternal plasma was collected from 72 SARS-CoV-2 IgG + participants of the Generation C Study, a birth cohort established at the beginning of the COVID-19 pandemic in New York City. Maternal SARS-CoV-2 anti-spike IgG antibody levels were measured using ELISA. A panel of 16 PFAS congeners were measured in maternal plasma using a targeted UHPLC-MS/MS-based assay. Spearman correlations and linear regressions were employed to explore associations between maternal IgG antibody levels and plasma PFAS concentrations. Weighted quantile sum (WQS) regression was also used to evaluate mixture effects of PFAS. Models were adjusted for maternal age, gestational age at which SARS-CoV-2 IgG titer was measured, COVID-19 vaccination status prior to IgG titer measurement, maternal race/ethnicity, parity, type of insurance and pre-pregnancy BMI.

RESULTS

Our study population is ethnically diverse with an average maternal age of 32 years. Of the 16 PFAS congeners measured, nine were detected in more than 60% samples. Importantly, all nine congeners were negatively correlated with SARS-CoV-2 anti-spike IgG antibody levels; n-PFOA and PFHxS, PFHpS, and PFHxA reached statistical significance (p < 0.05) in multivariable analyses. When we examined the mixture effects using WQS, a quartile increase in the PFAS mixture-index was significantly associated with lower maternal IgG antibody titers (beta [95% CI] = -0.35 [-0.52, -0.17]). PFHxA was the top contributor to the overall mixture effect.

CONCLUSIONS

Our study results support the notion that PFAS, including short-chain emerging PFAS, act as immunosuppressants during pregnancy. Whether such compromised immune activity leads to downstream health effects, such as the severity of COVID-19 symptoms, adverse obstetric outcomes or neonatal immune responses remains to be investigated.

High maternal glucose exacerbates the association between prenatal per- and polyfluoroalkyl substance exposure and reduced birth weight

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) exposure has been associated with reduced birth weight. However, the association may be complicated by glucose status due to PFAS impact on fetal growth and placental transport.

OBJECTIVES

To examine whether maternal glucose status modifies the association between prenatal PFAS exposure and birth weight z-score.

METHODS

We analyzed data of 1405 mother-child pairs from the prospective Shanghai Birth Cohort. Plasma concentrations of six PFAS were quantified in the first trimester. Fasting plasma glucose (FPG) was collected at 24-28 gestation weeks. A range of FPG cutoffs (4.9-5.4 mmol/L) covering current recommendations for gestational diabetes mellitus were used to define high and low FPG groups. Association between PFAS concentration and birth weight z-score was evaluated using multivariate linear regression in two FPG groups respectively, and the dose-response relationship was estimated with cutoffs ranging from low to high. We then used propensity score to counterbalance the effects of different PFAS concentrations between the high and low FPG groups, and run the regression again.

RESULTS

A doubling increase in concentrations of several PFAS was inversely associated with birth weight z-score. The association was more evident in high FPG groups and the magnitudes intensified when FPG cutoff increased. The strongest association was observed for PFOA, with the magnitude increased from -0.34 (95 % CI: -0.66, -0.03) for 5.0 mmol/L cutoff, to -0.41 (95 % CI: -0.77, -0.05) for 5.1 mmol/L cutoff, and further to -0.51 (95 % CI: -0.98, -0.03) for 5.3 mmol/L. Propensity score matching yielded similar results.

CONCLUSIONS

High maternal glucose level may increase the risk of reduced birth weight z-score related to prenatal PFAS exposure. Moreover, exploring the effects with different FPG cutoffs may contribute to providing intervention strategies for pregnant women with high PFAS exposure.

The Association between Prenatal Per- and Polyfluoroalkyl Substances Exposure and Neurobehavioral Problems in Offspring: A Meta-Analysis

Exposure to per- and polyfluoroalkyl substances (PFAS) during pregnancy has been suggested to be associated with neurobehavioral problems in offspring. However, current epidemiological studies on the association between prenatal PFAS exposure and neurobehavioral problems among offspring, especially attention deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD), are inconsistent. Therefore, we aimed to study the relationship between PFAS exposure during pregnancy and ADHD and ASD in offspring based on meta-analyses. Online databases, including PubMed, EMBASE, and Web of Science, were searched comprehensively for eligible studies conducted before July 2021. Eleven studies (up to 8493 participants) were included in this analysis. The pooled results demonstrated that exposure to perfluorooctanoate (PFOA) was positively associated with ADHD in the highest quartile group. Negative associations were observed between perfluorooctane sulfonate (PFOS) and ADHD/ASD, including between perfluorononanoate (PFNA) and ASD. There were no associations found between total PFAS concentration groups and neurobehavioral problems. The trial sequential analyses showed unstable results. Our findings indicated that PFOA and PFOS exposure during pregnancy might be associated with ADHD in offspring and that prenatal PFOS and PFNA exposure might be associated with ASD in offspring. According to the limited evidence obtained for most associations, additional studies are required to validate these findings.

Prenatal exposure to per- and polyfluoroalkyl substances and childhood adiposity at 7 years of age

BACKGROUND

An increasing number of studies have reported that prenatal per- and polyfluoroalkyl substances (PFAS) exposure may increase childhood adiposity. However, limited data is available in China, and the overall effects of PFAS mixture remain unclear.

OBJECTIVE

To examine the association of prenatal exposure to individual PFAS and their mixture with childhood adiposity at 7 years of age.

METHODS

A total of 206 mother-infant pairs were recruited from the Laizhou Wan (Bay) Birth Cohort in China between 2010 and 2013. Ten PFAS were measured in maternal serum. The measurements of fat mass, body fat percentage, body mass index, waist circumference, waist-to-height ratio and overweight/obesity were used to assess adiposity in children aged 7. We fitted logistic regression, linear regression and weighted quantile sum (WQS) regression models to estimate the association of prenatal exposure to individual PFAS and their mixture with childhood adiposity.

RESULTS

We found negative associations of perfluoroheptanoic acid (PFHpA) and perfluorooctane sulfonamide (PFOSA) exposure with adiposity measurements in all children. The result from the WQS model consistently revealed that the PFAS mixture was inversely related to adiposity measurements. Each quartile increase of the PFAS mixture was associated with a 1.14 kg decrease (95% CI: -2.27, -0.02) in fat mass and a 2.32% decrease (95% CI: -4.51, -0.14) in body fat. Moreover, significant sex differences were found. PFAS mixture was negatively associated with five adiposity measurements in boys, but positively associated with all adiposity measurements except body fat percentage in girls. PFOSA, PFHpA and perfluorobutanesulfonate (PFBS) with weights >0.300 were the main contributors to the overall effects observed among all children, boys and girls, respectively.

CONCLUSION

This study suggests potential sex-specific associations of prenatal exposure to individual PFAS and their mixture with childhood adiposity, with the observed relationship being negative for boys but positive for girls.

Association of single and multiple prefluoroalkyl substances exposure with preterm birth: Results from a Chinese birth cohort study

BACKGROUND

Perfluoroalkyl substances (PFASs) are persistent organic pollutants that may lead the adverse birth outcomes, including preterm birth (PTB). However, previous studies have reported inconsistent results on the association between PFASs and PTB, and lack of the epidemiological evidence regarding the effect of PFASs mixture on PTB. This study aimed to explore association of individual and multiple exposure to PFASs with PTB.

METHODS

The study subjects were consisted of 1341 pregnant women from Guangxi Zhuang Birth Cohort in Guangxi, China, from June 2015 to April 2019. Nine PFASs concentrations in the maternal serum were examined by ultrahigh liquid performance chromatography-tandem mass spectrometry, and the gestational weeks were obtained from medical records. We applied binary logistics regression model to explore correlation between individual PFAS and PTB and inspected the combined effect of PFASs mixture on PTB by applying Bayesian kernel machine regression (BKMR) and weighted quantile sum (WQS) regression models.

RESULTS

In adjusted logistics regression model, perfluorooctane sulfonate (PFOS), perfluoroheptanoic acid (PFHpA), perfluorobutanesulfonic acid (PFBS), ∑perfluorinated sulfonic acids (PFSA), and ∑PFASs were positively associated with the risk of PTB. In contrast, perfluoroundecanoic acid (PFUnA), perfluorohexane sulfonate (PFHxS), and perfluorooctanoic acid (PFOA) were negatively associated with the risk of PTB. These associations of n PFOS and PFHpA with PTB were found to be more pronounced in male infants. Restricted cubic splines (RCSs) showed an inverse U-shaped relationship between PFBS and PTB. Analysis from BKMR model showed a positive association between PFASs mixture and PTB, and no evidence of interactions among the nine PFASs were detected. Additionally, PFHpA, PFOS, and PFBS were identified as the main contributors for the effect of PFASs mixture on increasing the risk of PTB by BKMR and WQS models.

CONCLUSION

Prenatal exposure to higher levels of PFASs mixture was associated with higher risk of PTB.

Exposure to perfluoroalkyl substances and neurodevelopment in 2-year-old children: A prospective cohort study

BACKGROUND

Humans are widely exposed to per- and polyfluoroalkyl substances (PFAS). As fetal stage is a critical window for neurodevelopment, it is important to know if in utero exposure to PFAS affects fetal neurodevelopment. However, previous human studies are both limited and inconsistent.

OBJECTIVES

To investigate the relationship between PFAS exposure during early pregnancy and the neurodevelopmental status at 2 years of age in a prospective cohort study.

METHODS

We measured 10 PFAS in maternal plasma samples collected prior to 16 weeks of gestation in the Shanghai Birth Cohort Study between 2013 and 2016. Childhood neurodevelopment was assessed at 2 years of age using the Bayley Scales of Infant and Toddler Development-Third Edition (BSID-III). Associations with domain specific scores for individual PFAS were assessed by multiple linear regression and binary logistic regression when scores were dichotomized. Quantile-based g-computation was used to estimate the joint effects of PFAS mixture.

RESULTS

A total of 2257 mother-child pairs who had both PFAS and BSID measurements were included in our analyses. The means and standard deviations of comprehensive scores were 115 ± 22, 96 ± 15 and 108 ± 15 for cognition, language, and motor, respectively. In multiple linear regressions, we observed significant negative associations of perfluorooctane sulfonate (PFOS), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDeA), perfluoroundecanoic acid (PFUnDA) with cognitive scores; PFNA, PFDeA, PFUnDA and perfluorohexanesulfonate (PFHxS) negatively with language scores; and PFNA and PFUnDA negatively with motor scores. Quantile-based g-computation showed that PFAS mixture was significantly associated with decreased cognitive and language scores, with an estimated β of -2.1 [95% confidence interval (CI): -3.5, -0.7)] and -2.0 (95% CI: -2.9, -1.0) per one quartile increase in PFAS mixture for cognitive and language domains, respectively. PFAS mixture was associated with increased odds of low cognition (adjusted odds ratio [OR] = 1.3, 95% CI:1.0, 1.6) and language scores (OR = 1.2, 95% CI: 1.1, 1.3).

CONCLUSIONS

PFAS exposure during early pregnancy was significantly associated with the adverse neurodevelopmental status at 2 years of age, which raises a serious public health concern.

Demographic, life-style and physiological determinants of serum per- and polyfluoroalkyl substance (PFAS) concentrations in a national cross-sectional survey of Swedish adolescents

PER: and polyfluoroalkyl substances (PFAS) may affect adolescent health, yet factors related to PFAS concentrations in serum are poorly understood. We studied demographic, life-style and physiological determinants of serum PFAS concentrations in Swedish adolescents from a nation-wide survey, Riksmaten Adolescents 2016-17 (RMA, age 10-21 years, n = 1098). Serum samples were analyzed for 42 PFAS, using liquid chromatography-tandem mass spectrometry. The cumulative probability model was used to estimate associations between serum PFAS and determinants, using ordinal logistic regression. Legacy linear (lin-) perfluorooctanoic acid (PFOA), perfluorononaoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), lin-perfluorohexanesulfonic acid (PFHxS) and lin-/branched (br-) perfluorooctanesulfonic acid (PFOS) were quantifiable in ≥70% of the samples. The emerging PFAS 9-chlorohexanedecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS) was quantified in 5.4% of the samples, suggesting initiation of long-range transport far from production sites. Median concentrations of all legacy PFAS were <2 ng/g serum, with a few participants having very high (>100 ng/g serum) lin-PFHxS and lin-/br-PFOS concentrations due to previous high exposure from PFAS-contaminated drinking water. Legacy PFAS exposure was strongly associated with birth country of the participants and their mothers. 2-fold higher estimated adjusted mean (EAM) concentrations were seen among high income country participants with mothers from high income countries than among low/lower-middle income country participants with mothers from the same category. Menstruating females had lower br-PFOS EAM concentrations than those who were not. Iron status (plasma ferritin) among females may be a marker of intensity of menstrual bleeding, but it was not significantly associated with legacy PFAS concentrations among females. Further studies are needed to determine how physiological changes occurring around menstruation affect the toxicokinetics of PFAS in females. In conclusion, PFAS are pollutants of the industrialized world and some of the identified determinants may be overlooked confounders/effect modifiers that should be included in future PFAS/health studies among adolescents.

A High-Throughput Toxicity Screen of 42 Per- and Polyfluoroalkyl Substances (PFAS) and Functional Assessment of Migration and Gene Expression in Human Placental Trophoblast Cells

Per- and polyfluoroalkyl substances (PFAS) have become ubiquitous environmental contaminants that have been associated with adverse pregnancy outcomes in women and experimental research models. Adverse developmental and reproductive outcomes have been investigated for relatively few PFAS, and such studies are not scalable to address the thousands of unique chemical structures. As the placenta has been reported as a PFAS target tissue, the human placental trophoblast JEG-3 cell line was employed in a high-throughput toxicity screen (HTTS) to evaluate the effects of 42 unique PFAS on viability, proliferation, and mitochondrial membrane potential (MMP). HTTS concentration-response curve fitting determined EC50 values for 79% of tested compounds for at least one of the three endpoints. Trophoblast migratory potential was evaluated for a subset of six prioritized PFAS using a scratch wound assay. Migration, measured as the percent of wound closure after 72 h, was most severely inhibited by exposure to 100 µM perfluorooctanoic acid (PFOA; 72% closure), perfluorooctanesulfonic acid (PFOS; 57% closure), or ammonium perfluoro-2-methyl-3-oxahexanoate (GenX; 79% closure). PFOA and GenX were subsequently evaluated for disrupted expression of 46 genes reported to be vital to trophoblast health. Disrupted regulation of oxidative stress was suggested by altered expression of GPEX1 (300 µM GenX and 3 µM GenX), GPER1 (300 µM GenX), and SOD1 and altered cellular response to xenobiotic stress was indicated by upregulation of the placental efflux transporter, ABCG2 (300 µM GenX, 3 µM GenX, and 100 µM PFOA). These findings suggest the placenta is potentially a direct target of PFAS exposure and indicate that trophoblast cell gene expression and function are disrupted at PFAS levels well below the calculated cytotoxicity threshold (EC50). Future work is needed to determine the mechanism(s) of action of PFAS towards placental trophoblasts.

Prenatal exposure to per- and polyfluoroalkyl substances, fetal thyroid hormones, and infant neurodevelopment

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are believed to impair early neurodevelopment and disrupt thyroid hormone (TH) levels. However, there are limited epidemiological data on the neurodevelopmental effects in infancy of prenatal PFAS exposure and the potential mediating effects of TH.

OBJECTIVES

To evaluate potential associations between prenatal PFAS exposure and early neurodevelopmental deficiencies, and assess mediator effects of TH.

METHODS

From 2010 to 2013, 274 mother-infant pairs were recruited to the Laizhou Wan Birth Cohort in China. Ten PFAS and five TH were measured in cord serum. Developmental quotient (DQ) from 5 domains (adaptive, social, language, gross and fine motor) was assessed using Gesell Developmental Schedules for each child at 1 year of age. The associations between PFAS and DQs were evaluated using multivariable linear regressions. TH-mediated effects of PFAS on DQs were calculated by mediation analyses.

RESULTS

Among our study population, PFAS exposures were common and associated with DQ decrement in infants. For each 10-fold increase in PFBS concentrations, gross motor and adaptive DQ decreased by 8.56 (95%CI: -15.15, -1.97) and 5.87 (95%CI: -8.07, -3.67) points, respectively. TSH mediated 12.90% of the association of PFBS with gross motor DQ and FT4 explained 19.63% of the association of PFBS with adaptive DQ. The negative association was also found between PFHxS exposure and gross motor DQ (β = 8.14, 95%CI: -15.39, -0.98).

CONCLUSIONS

PFBS and PFHxS were negatively associated with early neurodevelopment, especially consistent in gross motor domain. The associations were partly explained by TSH and FT4.

Prenatal Exposure to Per- and Polyfluoroalkyl Substances and Child Growth Trajectories in the First Two Years

BACKGROUND

Pregnant women are ubiquitously exposed to per- and polyfluoroalkyl substances (PFAS). Prenatal exposure to PFAS has been associated with lower birth weight but also with excess adiposity and higher weight in childhood. These mixed findings warrant investigation of the relationship between PFAS and dynamic offspring growth.

OBJECTIVES

To investigate the association between prenatal PFAS exposure and early-life growth trajectories during the first 2 y.

METHODS

Pregnant women (n=3,426) were recruited from 2013 to 2016 from the Shanghai Birth Cohort (SBC) Study, and their children were followed up from birth to 2 y of age. Seven PFAS congeners were quantified in pregnant women's serum during the first trimester. Our study population was restricted to 1,350 children who had five repeated measurements for at least one anthropometric measure. Four anthropometric measures, including weight, length/height, weight-for-length, and head circumference, were evaluated at birth, 42 d, 6 months, 12 months, and 24 months, and standardized into z-scores using the World Health Organization reference. Trajectories of each measure were classified into five groups using group-based trajectory modeling. Multinomial logistic regression was used to estimate odds ratio (OR) and 95% confidence interval (CI) for trajectory groups according to log2-transformed PFAS concentrations, and the moderate-stable group was selected as the reference group for all measures.

RESULTS

Higher prenatal exposure to PFAS was associated with elevated odds for the low-rising weight-for-age z-score (WAZ) trajectory, and the high-rising length-for-age z-score (LAZ) trajectory. Meanwhile, PFAS levels were associated with decreased odds for the low-rising and high-rising weight-for-length z-score (WLZ) trajectories. In addition, the associations of PFAS with growth trajectory groups differed by sex, where males had greater odds for the low-rising and low-stable WAZ trajectories and for the high-stable and low-rising WLZ trajectories. In contrast, inverse associations were consistently observed with trajectories of the high-stable, low-stable, and low-rising head-circumference-for-age z-score (HCZ) in relation to most individual PFAS congeners. PFAS mixtures analysis further confirmed the above findings.

DISCUSSION

Trajectory analysis approach provided insight into the complex associations between PFAS exposure and offspring growth. Future studies are warranted to confirm the present findings with trajectory modeling strategies and understand the clinical significance of these trajectory groups. https://doi.org/10.1289/EHP9875.

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

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

Association between maternal serum concentration of perfluoroalkyl substances (PFASs) at delivery and acute infectious diseases in infancy

BACKGROUND

Perfluoroalkyl substances (PFASs) are persistent and bio-accumulative compounds that have been recognized as important immune hazards by animal studies. However, epidemiological studies regarding the impact on infant infections were inconsistent.

OBJECTIVES

We investigated the associations between prenatal exposure to PFASs and acute infectious diseases including common cold, bronchitis/pneumonia, and diarrhea in early childhood.

METHODS

Participating 235 mother-infant pairs were recruited from the Laizhou Wan (Bay) birth cohort (LWBC), a prospective study in Shandong, China between September 2010 and 2013. Ten selected PFASs congeners including PFOA, PFOS, PFNA, PFDA, PFUA, PFDoA, PFHxS, PFBS, PFHpA, and PFOSA were measured from maternal serum by HPLC-MS/MS. Detailed information on parent-reported frequency of acute infectious diseases was collected from questionnaires at 1-year follow-up, which was confirmed by the medical records. Logistic and Poisson regression models were used on binary health outcomes (yes/no) and the number of episodes of outcomes, which were reported as odds ratio (OR) and incidence rate-ratio (IRR), respectively.

RESULTS

The risk of diarrhea increased by 4.99 (95% CI = 1.86, 13.39) per log-unit increase in PFOA. The frequencies of diarrhea increased by 97%-116% for each 10-fold increase in PFOA, PFNA, and PFDA. Moreover, when stratified by exclusively breastfeeding duration (at least 4 months or not), the adverse effects of PFASs exposures on diarrhea were more pronounced among the breastfed infants. There were no associations between prenatal PFASs exposure and common cold or bronchitis/pneumonia.

CONCLUSIONS

Exposure to PFASs was associated with increased risks of diarrhea during the first year of life, and these effects were stronger among the breastfed infants. Due to the small sample size, our results should be interpreted with caution and additional studies on larger populations are needed to confirm our findings.

The transplacental transfer efficiency of per- and polyfluoroalkyl substances (PFAS): a first meta-analysis

Per- and polyfluorinated substances (PFAS), ubiquitously present in the environment and biota, are transferred to the fetus via the placenta. PFAS can be distinguished, among other things, by their different carbon chain lengths and functional groups. The aim of this study was to provide comprehensive evidence on PFAS transfer rates across the human placental barrier by means of a meta-analysis based upon a systematic review. The available literature up to April 2021 was reviewed and transplacental transfer efficiencies (TTEs) of PFAS assessed. A total of 39 studies reporting data on 20 PFAS were included in the systematic review. Of these, 20 studies with data on 19 compounds were included in the meta-analysis. Comprehensive Meta-Analysis (CMA v3.0) was used for quantitative, statistical analyses with random effects models. A curvilinear relationship was found with short and long chains of perfluorocarboxylic acids (PFCAs) exhibiting higher TTE than compounds with intermediate chain length. Among the less well studied PFAS, perfluorohexanoic acid (PFHxA), 6:2 fluorotelomersulfonic acid (6:2 FTS) and perfluorobutanoic acid (PFBA) stood out the most with a high TEEs. The dependence of TTEs on chain length and functional group is clearly shown in this first meta-analysis on PFAS transfer across the human placenta. More data on effects of less well studied PFAS in pregnant women and neonates are needed to assess the potential risk for fetal exposure.

Correlates of plasma concentrations of per- and poly-fluoroalkyl substances among reproductive-aged Black women

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals used in commercial and consumer goods. Black women are underrepresented in studies of PFAS exposure.

METHODS

We performed a cross-sectional analysis of correlates of plasma PFAS concentrations among 1499 Black women aged 23-35 participating in the Study of Environment, Lifestyle, and Fibroids (SELF), a Detroit-based cohort study. At baseline (2010-2012), participants provided questionnaire data on socio-demographics; behaviors; diet; and menstrual, contraceptive, and reproductive histories. Using mass spectrometry in non-fasting plasma samples collected at enrollment, we quantified several PFAS, including perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorodecanoate (PFDA), perfluoroundecanoate (PFUnDA), and 2-N-methyl-perfluorooctane sulfonamido acetate (MeFOSAA). We used linear regression to calculate percentage differences (%D) and 95 % confidence intervals (CIs) for associations between selected correlates and PFAS concentrations, adjusting for all other correlates.

RESULTS

PFHxS, PFOS, PFOA, and PFNA were detected in ≥97 % of women; PFDA in 86 %; MeFOSAA in 70 %; and PFUnDA in 52 %. Age, income, education, and intakes of water, alcohol, and seafood were positively associated with several PFAS. Current smoking was positively associated with MeFOSAA. Body mass index was inversely associated with most PFAS, except PFHxS. Strong inverse associations (%D; 95 % CI) were observed between parity (≥3 vs. 0 births) and PFHxS (-34.7; -43.0, -25.1) and PFOA (-33.1; -39.2, -26.3); breastfeeding duration (≥6 months vs. nulliparous) and PFOA (-31.1; -37.8, -23.7), PFHxS (-24.2; -34.5, -12.3), and PFOS (-18.4; -28.3, -7.1); recent birth (<2 years ago vs. nulliparous) and PFOA (-33.1; -39.6, -25.8), PFHxS (-29.3; -39.0, -18.1), PFNA (-25.2; -32.7, -16.8), and PFOS (-18.3; -28.3, -6.9); and intensity of menstrual bleed (heavy vs. light) and PFHxS (-18.8; -28.3, -8.2), PFOS (-16.4; -24.9, -7.1), PFNA (-10.5; -17.8, -2.6), and PFOA (-10.0; -17.2, -2.1). Current use of depot medroxyprogesterone acetate (DMPA) was positively associated with PFOS (20.2; 1.4, 42.5), PFOA (16.2; 1.5, 33.0), and PFNA (15.3; 0.4, 32.4).

CONCLUSIONS

Reproductive factors that influence PFAS elimination showed strong associations with several PFAS (reduced concentrations with parity, recent birth, lactation, heavy menstrual bleeding; increased concentrations with DMPA use).

Associations of paternal and maternal per- and polyfluoroalkyl substances exposure with cord serum reproductive hormones, placental steroidogenic enzyme and birth weight

BACKGROUND

Maternal per- and polyfluoroalkyl substances (PFAS) exposure has been associated with placental function and fetal growth measures. However, few studies have simultaneously investigated paternal and maternal exposure effects.

OBJECTIVES

We evaluated the associations of paternal or maternal PFAS levels with placental function and fetal growth measures.

METHODS

We studied six PFAS measured in matched parental serums collected within 3 days before delivery in a birth cohort from LaiZhouWan, China. Outcomes evaluated include cord serum estradiol (n = 351), testosterone (n = 349), placental P450aromatase (n = 125), and birth weight (n = 369). Multiple linear regression was applied to estimate the associations for these outcomes according to paternal or maternal PFAS level after adjusting for socio-demographic confounders. Co-adjustment analysis of both paternal and maternal PFAS in the same model was performed.

RESULTS

Maternal and paternal PFAS levels were correlated (Spearman's r = 0.23-0.45). Maternal PFAS were associated with increased estradiol (e.g.

, PFOA

β = 0.03, 95%CI: 0.00, 0.07), testosterone (e.g.

, PFUA

β = 0.14, 95%CI: 0.00, 0.27), and P450aromatase (e.g.

, PFOA

β = 0.13, 95%CI: 0.04, 0.22). Maternal PFAS were also associated with a lower mean of birth weight but the estimated 95% CI included the null. Paternal PFAS were not associated with any of the outcomes evaluated.

CONCLUSIONS

Several maternal PFAS were associated with fetal steroid hormones and placental enzymes. Despite a correlation of PFAS level within the couples, no association was found for paternal PFAS exposure on these outcomes. The findings suggest the intrauterine PFAS exposure effect on fetal endocrine hormones and growth is unlikely to be confounded by exposure sources or familial factors shared within the couples.

Per- and polyfluoroalkyl substances exposure during pregnancy and adverse pregnancy and birth outcomes: A systematic review and meta-analysis

BACKGROUND

Exposure to per- and polyfluoroalkyl substances (PFAS) during pregnancy has been suggested to be associated with adverse pregnancy and birth outcomes; however, the findings have been inconsistent. We aimed to conduct a systematic review and meta-analysis to provide an overview of these associations.

METHODS

The online databases PubMed, EMBASE and Web of Science were searched comprehensively for eligible studies from inception to February 2021. Odds ratios (ORs) and 95% confidence intervals (CIs) were pooled using random- or fixed-effects models, and dose-response meta-analyses were also conducted when possible.

FINDINGS

A total of 29 studies (32,905 participants) were included. The pooled results demonstrated that perfluorooctane sulfonate (PFOS) exposure during pregnancy was linearly associated with increased preterm birth risk (pooled OR per 1-ng/ml increase: 1.01, 95% CIs: 1.00-1.02, P = 0.009) and perfluorononanoate (PFNA) and perfluorooctanoate (PFOA) exposure showed inverted U-shaped associations with preterm birth risk (P values for the nonlinear trend: 0.025 and 0.030). Positive associations were also observed for exposure to perfluorodecanoate (PFDA) and miscarriage (pooled OR per 1-ng/ml increase: 1.87, 95% CIs: 1.15-3.03) and PFOS and preeclampsia (pooled OR per 1-log increase: 1.27, 95% CIs: 1.06-1.51), whereas exposure to perfluoroundecanoate (PFUnDA) was inversely associated with preeclampsia risk (pooled OR per 1-log increase: 0.81, 95% CIs: 0.71-0.93). Based on individual evidence, detrimental effects were observed between PFDA exposure and small for gestational age and between PFOA and PFOS and intrauterine growth restriction. No significant associations were found between pregnancy PFAS exposure and other adverse pregnancy outcomes (i.e., gestational diabetes mellitus, pregnancy-induced hypertension, low birth weight, and large and small for gestational age).

INTERPRETATION

Our findings indicated that PFOS, PFOA and PFNA exposure during pregnancy might be associated with increased preterm birth risk and that PFAS exposure might be associated with the risk of miscarriage and preeclampsia. Due to the limited evidence obtained for most associations, additional studies are required to confirm these findings.

Nitric oxide mediates disruption of human placental trophoblast invasion induced by perfluorobutane sulfonate

Perfluorobutane sulfonate (PFBS), an emerging pollutant, is associated with disruption of placental functions and adverse birth outcomes. However, the precise mechanism of this disruption remains unclear. Extravillous trophoblasts make up the majority of cells in the placenta, and have invasive abilities, which plays a critical role in a successful pregnancy. It has been reported that inducible nitric oxide (iNOS) and nitric oxide (NO) signaling is associated with trophoblast migration and invasion. In this study, PFBS exposure was found to enhance trophoblast invasion and increase matrix metalloproteinase 9 (MMP-9) levels. Additionally, PFBS upregulated iNOS levels and stimulated NO generation. iNOS inhibitor treatment attenuated the increased invasion of trophoblasts and MMP-9 expression induced by PFBS. Extracellular signal-regulated kinase (ERK) phosphorylation was also enhanced by PFBS exposure. In the presence of an ERK pathway inhibitor, however, the increases in trophoblast invasion, the induction of NO production, iNOS expression and MMP-9 expression induced by PFBS were attenuated. Taken together, these results suggest that iNOS/NO signaling is triggered by activation of the ERK signaling pathway, and that iNOS/NO signaling mediates PFBS-induced stimulation of trophoblast invasion.

Prenatal exposure and transplacental transfer of perfluoroalkyl substance isomers in participants from the upper and lower reaches of the Yangtze River

Data on gestational exposure characteristics and transplacental transfer are quite limited for perfluoroalkyl substance (PFAS) isomers, especially those from large-scale comparative studies. To fill this gap, we examined isomers of perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorohexane sulfonic acid (PFHxS) in matched maternal and cord serum from Mianyang and Hangzhou, which are located in the upper and lower reaches of the Yangtze River, China, respectively. These data were compared with those from our previous study on Wuhan in the middle reach. The average ΣPFAS concentration increased from upstream to downstream (Mianyang (4.44 ng/mL) < Wuhan (9.88 ng/mL) < Hangzhou (19.72 ng/mL)) and may be related to the per capita consumption expenditure of each city. The ln-transformed PFAS concentrations showed significant differences between Mianyang and Hangzhou after adjusting confounding factors (p < 0.05). The percentages of linear PFOS and PFOA in maternal and cord serum from these cities all exceeded those in electrochemical fluorination products. The isomer profiles of PFASs in maternal and cord serum might be greatly influenced by local production processes of PFASs and residents' dietary habits. The transplacental transfer efficiencies decreased significantly with increasing concentrations in maternal serum for ΣPFAS, ΣPFOS, ΣPFOA, ΣPFHxS, n-PFOS, iso-PFOS, 4m-PFOS, 1m-PFOS, n-PFOA, n-PFHxS, and br-PFHxS (Spearman rank correlation coefficients (r) = 0.373-0.687, p < 0.01). These findings support an understanding of the regional characteristics in maternal exposure to PFASs along the Yangtze River, isomeric profiles of PFASs in these regions, and the transplacental transfer processes of PFAS isomers.

Transplacental Transfer of Environmental Chemicals: Roles of Molecular Descriptors and Placental Transporters

Transplacental transfer of environmental chemicals results in direct risks to fetal development. Although numerous studies have investigated transplacental transfer efficiencies (TTEs) of environmental chemicals, the underlying mechanisms and influencing factors remain poorly understood. The present study aims to synthesize a current state of knowledge on the TTEs of major environmental chemicals and explore the roles of chemicals' molecular descriptors and placental transporters in the transplacental transfer. The results indicate great variations in TTEs (median: 0.29-2.86) across 51 chemicals. Chemical-dependent TTEs may partially be attributed to the influences of chemicals' molecular descriptors. Predictive models based on experimental TTEs and 1790 computed molecular descriptors indicate that a very limited number of molecular descriptors, such as the topological polar surface area, may substantially influence and efficiently predict chemicals' TTEs. In addition, molecular docking analyses were conducted to determine the binding affinities between 51 chemicals and six selected transporters, including BCRP, MDR1, hENT1, FRα, SERT, and MRP1. The results reveal transporter- and chemical-dependent binding affinities. Therefore, our study demonstrates that molecular descriptors and placental transporters, among a variety of other factors, can play important roles in the transplacental transfer of environmental chemicals. However, the underlying mechanisms and several important knowledge gaps identified herein require further investigations.

A review of the transplacental transfer of persistent halogenated organic pollutants: Transfer characteristics, influential factors, and mechanisms

Persistent halogenated organic pollutants (HOPs) are a class of toxic chemicals, which may have adverse effects on fetuses via transplacental transfer from their mothers. Here, we review reported internal exposure levels of various HOPs (organochlorinated pesticides, polychlorinated biphenyls, polybrominated diphenyl ethers, short- and medium-chain chlorinated paraffins, and per- and poly-fluoroalkyl substances) in placenta, and both maternal and umbilical cord sera. We also present analyses of the transplacental transfer and placental distribution characteristics of each class of compounds, and discuss effects of several factors on the transfer and accumulation efficiencies of HOPs, as well as the main mechanisms of HOPs' transfer across the placental barrier. Reported compound-specific transplacental transfer efficiencies and distribution efficiencies, expressed as umbilical cord:maternal serum and placental:maternal serum concentration ratios (R_CM and R_PM, respectively), are summarized. Average published R_CM values of the HOPs range from 0.24 to 3.08 (lipid-adjusted) and from 0.04 to 3.1 (based on wet weights), and are highest for perfluoroalkylcarboxylates (PFCAs) and tetrabromobisphenol A. Average published R_PM values range from 0.14 to 1.02 (lipid-adjusted) and from 0.30 to 1.4 (based on wet weights). The broad R_CM and R_PM ranges may reflect effects of various factors, inter alia physicochemical properties of HOPs, metabolic capacities of mothers and fetuses, placental maturity, and differential expression of influx/efflux transporters in the placenta. Generally, HOPs' R_CM values decline linearly with molecular size, and are curvilinearly related to solubility. Plasma protein binding affinity and the difference between maternal and fetal metabolic capacities may also affect some HOPs' transfer efficiencies. HOPs' molecular size may be influential. Transplacental transport of HOPs likely occurs mostly through passive diffusion, although influx/efflux transporters expressed on maternal and/or fetal sides of the placenta may also facilitate or hinder their transport. Overall, the review highlights clear gaps in our understanding of mechanisms involved in HOPs' transplacental transport.

Exposure to perfluorobutane sulfonate and perfluorooctanesulfonic acid disrupts the production of angiogenesis factors and stress responses in human placental syncytiotrophoblast

Poly- and per-fluoroalkyl substances (PFAS) have attracted widespread attention in recent years due to their bioaccumulation, toxicity, and ubiquitous nature. We and others have reported that maternal exposure to PFAS is associated with adverse birth outcomes due to altered placental functions. In this study, we investigated the effects of two major PFAS compounds, perfluorobutane sulfonate (PFBS) and perfluorooctanesulfonic acid (PFOS), on the regulation of the production of angiogenic factors and stress response in placental multinucleated syncytial BeWo cells using qRT-PCR and ELISA. Using this in vitro model, we showed that 1) PFOS or PFBS treatment did not seem to interrupt BeWo cell fusion through syncytins; 2) Exposure to PFOS at 10 μM decreased a potent angiogenic factor PlGF gene expression, which is implicated in preeclampsia; 3) Exposure to either PFOS or PFBS significantly decreased the production of CGB7 and hCG except hCG secretion in PFOS (10 nM) and PFBS (100 nM) treatment groups; 4) Exposure to PFOS (10 μM) increased the gene expression of the stress response molecules CRH while neither PFOS nor PFBS treatment affected a stress mitigation factor 11β-HSD2 expression. Our results demonstrate that exposure to PFOS or PFBS impacts several key pathways involved in placental cell functions. PFOS seems more potent than PFBS. These novel findings provide a potential explanation for the adverse reproductive complications associated with prenatal exposure to PFOS or PFBS, including preeclampsia and contribute to our knowledge of the reproductive toxicity of PFAS, specifically PFOS and PFBS.

Exposure characteristics for congeners, isomers, and enantiomers of perfluoroalkyl substances in mothers and infants

Per- and polyfluoroalkyl substances (PFASs) are ubiquitous in the environment, making it inevitable for humans to be exposed to these pollutants. The exposure begins while in utero and continues in infancy, during the potentially most sensitive early stages of life. This review summarizes the current knowledge on pre- and neo-natal exposures based on more than 200 articles published from 2000 to date. All relevant biological matrices used in the cited studies were included, such as maternal blood, umbilical cord blood, breast milk, placenta, amniotic fluid, fetal organs, newborns' dried blood spots, and infant serum. We show that such exposures are geographically global with significant discrepancies among countries and continents, and that while the levels of major legacy PFASs (PFOS and PFOA) have declined since 2000, those of others may have not. We also show that levels of PFOS and PFOA exceed those of some major environmental toxins, such as p,p'-DDE, BDE-47, PCB-153, PBB-153, and OH-PBDEs in maternal blood. Given that the behavior and potential effects have an origin in molecular structure, biomonitoring and research at the levels of isomers and enantiomers are critically important. Through critical analysis of these works, we summarize the major achievements, consensus, and the deficiencies of existing research. To our knowledge, this is the first review on the overall internal exposure status of mothers and infants to PFASs during pregnancy and lactation.

Early life exposure to per- and polyfluoroalkyl substances (PFAS) and latent health outcomes: A review including the placenta as a target tissue and possible driver of peri- and postnatal effects

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous drinking water contaminants of concern due to mounting evidence implicating adverse health outcomes associated with exposure, including reduced kidney function, metabolic syndrome, thyroid disruption, and adverse pregnancy outcomes. PFAS have been produced in the U.S. since the 1940s and now encompass a growing chemical family comprised of diverse chemical moieties, yet the toxicological effects have been studied for relatively few compounds. Critically, exposures to some PFAS in utero are associated with adverse outcomes for both mother and offspring, such as hypertensive disorders of pregnancy (HDP), including preeclampsia, and low birth weight. Given the relationship between HDP, placental dysfunction, adverse health outcomes, and increased risk for chronic diseases in adulthood, the role of both developmental and lifelong exposure to PFAS likely contributes to disease risk in complex ways. Here, evidence for the role of some PFAS in disrupted thyroid function, kidney disease, and metabolic syndrome is synthesized with an emphasis on the placenta as a critical yet understudied target of PFAS and programming agent of adult disease. Future research efforts must continue to fill the knowledge gap between placental susceptibility to environmental exposures like PFAS, subsequent perinatal health risks for both mother and child, and latent health effects in adult offspring.

Perfluorobutane sulfonate exposure disrupted human placental cytotrophoblast cell proliferation and invasion involving in dysregulating preeclampsia related genes

We reported that maternal PFBS, an emerging pollutant, exposure is positively associated with preeclampsia which can result from aberrant trophoblasts invasion and subsequent placental ischemia. In this study, we investigated the effects of PFBS on trophoblasts proliferation/invasion and signaling pathways. We exposed a human trophoblast line, HTR8/SVneo, to PFBS. Cell viability, proliferation, and cell cycle were evaluated by the MTS assay, Ki-67 staining, and flow cytometry, respectively. We assessed cell migration and invasion with live-cell imaging-based migration assay and matrigel invasion assay, respectively. Signaling pathways were examined by Western blot, RNA-seq, and qPCR. PFBS exposure interrupted cell proliferation and invasion in a dose-dependent manner. PFBS (100 μM) did not cause cell death but instead significant cell proliferation without cell cycle disruption. PFBS (10 and 100 μM) decreased cell migration and invasion, while PFBS (0.1 μM) significantly increased cell invasion but not migration. Further, RNA-seq analysis identified dysregulated HIF-1α target genes that are relevant to cell proliferation/invasion and preeclampsia, while Western Blot data showed the activation of HIF-1α, but not Notch, ERK1/2, (PI3K)AKT, and P38 pathways. PBFS exposure altered trophoblast cell proliferation/invasion which might be mediated by preeclampsia-related genes, suggesting a possible association between prenatal PFBS exposure and adverse placentation.

Association of perfluoroalkyl substances with gestational hypertension and preeclampsia in the MIREC study

BACKGROUND

Perfluoroalkyl substances (PFAS) have been linked with a number of developmental, reproductive, hepatic, and cardiovascular health outcomes. However, the evidence for an association between PFAS and hypertensive disorders of pregnancy (including gestational hypertension and preeclampsia) is equivocal and warrants further investigation.

OBJECTIVES

To examine the relationship between background levels of perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and perfluorohexane sulfonate (PFHxS) and the development of gestational hypertension or preeclampsia in a Canadian pregnancy cohort. We also explored the potential for effect modification according to fetal sex.

METHODS

Maternal plasma samples were collected in the first trimester from participants in the MIREC study and were analyzed for PFOA, PFOS, and PFHxS. Blood pressure was measured during each trimester. Gestational hypertension and preeclampsia were defined using the Society of Obstetricians and Gynaecologists of Canada guidelines. Logistic regression models were used to derive adjusted odds ratios (OR) and 95% confidence intervals (CI) for associations between PFAS concentrations (per doubling of concentration as well as according to tertiles) and gestational hypertension or preeclampsia. Linear mixed models were used to examine the association between PFAS concentrations and changes in blood pressure throughout pregnancy.

RESULTS

Data from 1739 participants were analyzed. 90% of women were normotensive throughout pregnancy, 7% developed gestational hypertension without preeclampsia, and 3% developed preeclampsia. In the full analyses, neither PFOA nor PFOS were associated with gestational hypertension or preeclampsia. However, each doubling of PFHxS plasma concentration was associated with higher odds of developing preeclampsia (OR = 1.32; 95% CI: 1.03, 1.70). In addition, participants in the highest PFHxS tertile (1.4-40.0 μg/L) had higher odds of developing preeclampsia relative to those in the lowest tertile (OR = 3.06; 95% CI: 1.27, 7.39). In stratified analyses, this effect was only apparent among women carrying a female fetus (OR = 4.90; 95% CI: 1.02, 22.3). However, among women carrying a male fetus, both PFOS and PFHxS were associated with gestational hypertension, but not preeclampsia. Higher plasma concentrations of all three PFAS were associated with increases in diastolic blood pressure throughout pregnancy, and PFOA and PFHxS were also associated with systolic blood pressure. Discrepant findings were similarly revealed in analyses stratified by fetal sex.

CONCLUSIONS

Higher levels of PFHxS were associated with the development of preeclampsia, but not gestational hypertension. Neither PFOA nor PFOS were associated with either outcome. However, we show, for the first time, that fetal sex may modify these associations, a finding which warrants replication and further study.

Transplacental Transfer of Per- and Polyfluoroalkyl Substances (PFASs): Differences between Preterm and Full-Term Deliveries and Associations with Placental Transporter mRNA Expression

Previous studies demonstrated that per- and polyfluoroalkyl substances (PFASs) can cross the human placental barrier. However, their transplacental transfer efficiencies (TTEs) have not been investigated in preterm delivery, and the role of placental transport proteins has rarely been explored. Our study hypothesized that the TTEs of PFASs could differ between preterm and full-term deliveries, and some placental transporters could be involved in active maternofetal PFAS transfer. In the present study, the median TTEs of 16 individual PFAS chemicals or isomers were determined to be 0.23 to 1.72 in matched maternal-cord serum pairs with preterm delivery (N = 86), which were significantly lower than those (0.35 to 2.26) determined in full-term delivery (N = 187). Significant associations were determined between the TTEs of several PFASs and the mRNA expression levels of selected transporters located on the brush border membrane. The association patterns also significantly differed between preterm and full-term deliveries and exhibited a chemical-specific manner. For example, the expression of MRP2 exhibited significantly positive associations with the TTEs of linear and branched perfluorooctanesulfonic acid (PFOS) isomers in full-term delivery, but negative, nonsignificant associations were observed in preterm delivery. This is the first study to compare the transplacental transfer of PFASs between preterm and full-term deliveries and indicate that some placental transport proteins could be involved in active transmission. The mechanisms underlying the cross-placental transfer of PFASs require further investigations to better elucidate their risks to fetal health and birth outcomes.

Prenatal perfluoroalkyl substances and newborn anogenital distance in a Canadian cohort

Exposure to the man-made chemicals perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS) and perfluorohexanesulfonate (PFHxS) is widespread. These perfluoroalkyl substances (PFASs) have been associated with androgenic endocrine-disrupting properties; however, the evidence is equivocal and few human studies have examined the association between prenatal exposure to PFASs and markers of androgenic endocrine disruption such as changes in anogenital distance (AGD). In the MIREC cohort, PFOA, PFOS and PFHxS were analyzed in first trimester maternal plasma. AGD was measured in 205 male and 196 female newborns. The change in estimate procedure was used to identify confounders by sex and AGD in multiple linear regression models. Geometric mean plasma concentrations (95% CI) for PFOA, PFOS and PFHxS were 1.71 (1.61, 1.81), 4.40 (4.18, 4.64) and 1.15 (1.06, 1.25) μg/L, respectively. A one-unit increase in natural log transformed PFOA was associated with a 1.36 mm (95% CI 0.30, 2.41) increase in anoscrotal distance, adjusting for household income, active smoking status during pregnancy and gestational age. However, when examined by quartiles, a non-monotonic pattern was observed with wide confidence intervals. No consistent patterns were observed between maternal PFAS concentrations and female AGDs. This study found no clear evidence that maternal plasma concentrations of PFOS, PFOA or PFHxS were associated with shorter infant anogenital distance in males or any change in AGD in females. Whether the positive association observed between longer anoscrotal distance and PFOA is real or would have any long-lasting effect on the reproductive health of males is unknown and needs to be investigated further.