Exposure to polyfluoroalkyl chemicals and attention deficit/hyperactivity disorder in U.S. children 12-15 years of age

A Systematic Review and Meta-analysis of Prenatal, Birth, and Postnatal Factors Associated with Attention-Deficit/Hyperactivity Disorder in Children

Previous studies have shown mixed results on the relationship between prenatal, birth, and postnatal ("pregnancy-related") risk factors and attention-deficit/hyperactivity disorder (ADHD). We conducted meta-analyses to identify potentially modifiable pregnancy-related factors associated with ADHD. A comprehensive search of PubMed, Web of Science, and EMBASE in 2014, followed by an updated search in January 2021, identified 69 articles published in English on pregnancy-related risk factors and ADHD for inclusion. Risk factors were included in the meta-analysis if at least three effect sizes with clear pregnancy-related risk factor exposure were identified. Pooled effect sizes were calculated for ADHD overall, ADHD diagnosis, inattention, and hyperactivity/impulsivity. Odds ratios (OR) were calculated for dichotomous measures and correlation coefficients (CC) for continuous measures. Prenatal factors (pre-pregnancy weight, preeclampsia, pregnancy complications, elevated testosterone exposure), and postnatal factors (Apgar score, neonatal illness, no breastfeeding) were positively associated with ADHD overall; the findings for ADHD diagnosis were similar with the exception that there were too few effect sizes available to examine pre-pregnancy weight and lack of breastfeeding. Prenatal testosterone was significantly associated with inattention and hyperactivity/impulsivity. Effect sizes were generally small (range 1.1-1.6 ORs, -0.16-0.11 CCs). Risk factors occurring at the time of birth (perinatal asphyxia, labor complications, mode of delivery) were not significantly associated with ADHD. A better understanding of factors that are consistently associated with ADHD may inform future prevention strategies. The findings reported here suggest that prenatal and postnatal factors may serve as potential targets for preventing or mitigating the symptoms of ADHD.

Prenatal and perinatal exposure to Per- and polyfluoroalkyl substances (PFAS)-contaminated drinking water impacts offspring neurobehavior and development

Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants ubiquitous in the environment and humans. In-utero PFAS exposure is associated with numerous adverse health impacts. However, little is known about how prenatal PFAS mixture exposure affects offspring's neurobehavioral function. This study aims to determine the causal relationship between in-utero PFAS mixture exposure and neurobehavioral changes in Sprague-Dawley rat offspring. Dams were exposed via drinking water to the vehicle (control), an environmentally relevant PFAS mixture, or a high-dose PFAS mixture. The environmentally relevant mixture was formulated to resemble measured tap water levels in Pittsboro, NC, USA (10 PFAS compounds; sum PFAS =758.6 ng/L). The high-dose PFAS load was 3.8 mg/L (5000×), within the range of exposures in the experimental literature. Exposure occurred seven days before mating until birth. Following exposure to PFAS-laden water or the vehicle during fetal development, neurobehavioral toxicity was assessed in male and female offspring with a battery of motor, cognitive, and affective function tests as juveniles, adolescents, and adults. Just before weaning, the environmentally relevant exposure group had smaller anogenital distances compared to the vehicle and high-dose groups on day 17, and males in the environmentally relevant exposure group demonstrated lower weights than the high-dose group on day 21 (p < 0.05). Reflex development delays were seen in negative geotaxis acquisition for both exposure groups compared to vehicle-exposed controls (p = 0.009). Our post-weaning behavioral measures of anxiety, depression, and memory were not found to be affected by maternal PFAS exposure. In adolescence (week five) and adulthood (week eight), the high PFAS dose significantly attenuated typical sex differences in locomotor activity. Maternal exposure to an environmentally relevant PFAS mixture produced developmental delays in the domains of pup weight, anogenital distance, and reflex acquisition for rat offspring. The high-dose PFAS exposure significantly decreased typical sex differences in locomotor activity.

A new mechanistic insight into the association between environmental perfluorooctane sulfonic acid (PFOS) exposure and attention deficit and hyperactivity disorder (ADHD)-like behavior

Perfluorooctane sulfonic acid (PFOS) is one of the main residual environmental pollutants that threaten human health. PFOS exposure is positively correlated with the prevalence of attention deficit hyperactivity disorder (ADHD); however, the underlying mechanism is unknown. Given that dopamine (DA) is a crucial target for PFOS and that its dysfunction is a key role in ADHD development, it is speculated that PFOS exposure contributes to the occurrence of ADHD to some extent by disrupting DA homeostasis. To establish the relationship between PFOS exposure, DA dysfunction, and ADHD-like behavior, adult zebrafish were exposed to PFOS for 21 days using PFOS concentrations in the serum of patients with ADHD as the reference exposure dose. Results showed that PFOS caused ADHD-like behaviors, with the presence of the slightly elevated percentage of time spent in movement and prolonged time spent in reaching the target zone in the T-maze. Hyperactivity and cognitive ability impairment were more severe with increasing PFOS concentrations. Further investigation showed that PFOS exposure resulted in a decrease in the DA content, accompanied by a decrease in the number of dopaminergic neurons and a disturbance in the transcription profiles of genes associated with the dopaminergic system. Treatment with Ritalin effectively alleviated PFOS-induced ADHD-like behavior and restored DA levels, number of dopaminergic neurons, and expression of DA metabolism-related genes, suggesting that PFOS exposure induced ADHD-like behavior by triggering DA secretion disorder. This study enriches our understanding of the pathogenic mechanisms underlying ADHD development and emphasizes the importance of focusing on the health risks pertaining to environmental exposure.

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

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

Evaluation of Neural Regulation and Microglial Responses to Brain Injury in Larval Zebrafish Exposed to Perfluorooctane Sulfonate

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are biopersistent, global pollutants. Although some in vitro and epidemiological studies have explored the neurotoxic potential of perfluorooctane sulfonate (PFOS), a prevalent PFAS congener, it is unknown how developmental PFOS exposure affects neuronal signaling, microglia development, and microglial-neuron communication.

OBJECTIVES

We sought to determine the extent to which PFOS exposure disrupts brain health, neuronal activity, and microglia-neuron communication during development. In addition, although PFOS impairs humoral immunity, its impact on innate immune cells, including resident microglia, is unclear. As such, we investigated whether microglia are cellular targets of PFOS, and, if so, whether disrupted microglial development or function could contribute to or is influenced by PFOS-induced neural dysfunction.

METHODS

Zebrafish were chronically exposed to either a control solution [0.1% dimethyl sulfoxide (DMSO)], 7 μ M PFOS, 14 μ M PFOS, 28 μ M PFOS, or 64 μ M perfluorooctanoic acid (PFOA). We used in vivo imaging and gene expression analysis to assess microglial populations in the developing brain and to determine shifts in the microglia state. We functionally challenged microglia state using a brain injury model and, to assess the neuronal signaling environment, performed functional neuroimaging experiments using the photoconvertible calcium indicator calcium-modulated photoactivatable ratiometric integrator (CaMPARI). These studies were paired with optogenetic manipulations of neurons and microglia, an untargeted metabolome-wide association study (MWAS), and behavioral assays.

RESULTS

Developmental PFOS exposure resulted in a shift away from the homeostatic microglia state, as determined by functional and morphological differences in exposed larvae, as well as up-regulation of the microglia activation gene p2ry12. PFOS-induced effects on microglia state exacerbated microglia responses to brain injury in the absence of increased cell death or inflammation. PFOS exposure also heightened neural activity, and optogenetic silencing of neurons or microglia independently was sufficient to normalize microglial responses to injury. An untargeted MWAS of larval brains revealed PFOS-exposed larvae had neurochemical signatures of excitatory-inhibitory imbalance. Behaviorally, PFOS-exposed larvae also exhibited anxiety-like thigmotaxis. To test whether the neuronal and microglial phenotypes were specific to PFOS, we exposed embryos to PFOA, a known immunotoxic PFAS. PFOA did not alter thigmotaxis, neuronal activity, or microglial responses, further supporting a role for neuronal activity as a critical modifier of microglial function following PFOS exposure.

DISCUSSION

Together, this study provides, to our knowledge, the first detailed account of the effects of PFOS exposure on neural cell types in the developing brain in vivo and adds neuronal hyperactivity as an important end point to assess when studying the impact of toxicant exposures on microglia function. https://doi.org/10.1289/EHP12861.

Exposure to environmental pollutants and attention-deficit/hyperactivity disorder: an overview of systematic reviews and meta-analyses

Although heritability estimates suggest a role for genetic components, environmental risk factors have been described as relevant in the etiology of attention deficit/hyperactivity disorder (ADHD). Several studies have investigated the role of toxicological pollution, i.e., air pollution, heavy metals, POPs, and phthalates. Clear evidence for association of ADHD and environmental factors has not been provided yet. To answer this, we have assessed all available systematic reviews and meta-analyses that focused on the association between pollutant exposure and either ADHD diagnosis or symptoms. More than 1800 studies were screened of which 14 found eligible. We found evidence of a significant role for some pollutants, in particular heavy metals and phthalates, in the increased risk of developing ADHD symptoms. However, at the current stage, data from existing literature also do not allow to weight the role of the different environmental pollutants. We also offer a critical examination of the reviews/meta-analyses and provide indications for future studies in this field. PROSPERO registration: CRD42022341496.

Priority list of potential endocrine-disrupting chemicals in food chemical contaminants: a docking study and in vitro/epidemiological evidence integration

Diet is an important exposure route of endocrine-disrupting chemicals (EDCs), but many unfiltered potential EDCs remain in food. The in silico prediction of EDCs is a popular method for preliminary screening. Potential EDCs in food were screened using Endocrine Disruptome, an open-source platform for inverse docking, to predict the binding probabilities of 587 food chemical contaminants with 18 human nuclear hormone receptor (NHR) conformations. In total, 25 contaminants were bound to multiple NHRs such as oestrogen receptor α/β and androgen receptor. These 25 compounds mainly include pesticides and per- and polyfluoroalkyl substances (PFASs). The prediction results were validated with the in vitro data. The structural features and the crucial amino acid residues of the four NHRs were also validated based on previous literature. The findings indicate that the screening has good prediction efficiency. In addition, the epidemic evidence about endocrine interference of PFASs in food on children was further validated through this screening. This study provides preliminary screening results for EDCs in food and a priority list for in vitro and in vivo research.

Effects of subchronic exposure of perfluorooctane sulfonate on cognitive function of mice and its mechanism

Perfluorooctane sulfonate (PFOS) is an emerging persistent organic pollutant, and its potential impact on cognitive function remains unclear. We adopted the C57BL/6J mouse model to investigate the effect of PFOS on cognitive function, as well as the underlying mechanisms. Subchronic exposure was performed by administering PFOS via drinking water for 6 months (at doses of 0, 0.2, and 2.0 mg/kg/day), starting from 10.5 months old. The object recognition ability was tested at 2, 4, and 6 months of exposure, and spatial learning and memory were assessed at endpoint. The apoptosis of neurons and astrocytes in the cortex and hippocampus was analyzed, as well as the potential apoptotic signaling pathways. Our results showed that exposure to PFOS for 6 months caused a decrease in object recognition ability and a decline in learning and spatial memory. PFOS selectively increased apoptosis in neurons of the cerebral cortex and specifically activated the endoplasmic reticulum stress PERK/CHOP signaling pathway. In conclusion, our results confirmed that subchronic exposure to PFOS can lead to cognitive impairment in mice, which might be closely associated with the specific activation of an endoplasmic reticulum stress-induced pro-apoptosis pathway in the cerebral cortex neurons.

Association between early-childhood exposure to perfluoroalkyl substances and ADHD symptoms: A prospective cohort study

There is evidence that exposure to perfluoroalkyl substances (PFAS) is associated with attention-deficit/hyperactivity disorder (ADHD) symptoms. Previous studies have focused on prenatal exposure to PFAS, and only few studies have examined the associations of early-childhood exposure, especially at low exposure levels. This study explored the association between early-childhood exposure to PFAS and ADHD symptoms later in childhood. In 521 children, we measured the serum levels of six PFAS in peripheral blood at the ages of 2 and 4 years, including perfluorooctanoate (PFOA), perfluornonanoicacid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorohexane sulfonic acid (PFHxS), and perfluorooctane sulfonate (PFOS). The ADHD Rating Scale IV (ARS) was utilized to measure ADHD traits at 8 years of age. We explored the relationship between PFAS and ARS scores using Poisson regression models after adjusting for potential confounders. Levels of exposure to individual PFAS and the summed value were divided into quartiles to examine possible nonlinear relationships. All six PFAS exhibited inverted U-shaped curves. Children in the 2nd and 3rd quartile levels of each PFAS showed higher ARS scores than those in the1^st quartile level. Below the 3rd quartile of the summed levels of six PFAS (ΣPFAS), a doubling of the ΣPFAS was associated with an 20.0 % (95 % CI: 9.5 %, 31.5 %) increase in ADHD scores. However, at the age of 4 years, none of the evaluated PFAS exhibited linear or nonlinear associations with the ARS scores. Thus, school-aged children may be vulnerable to the neurotoxic effects of exposure to PFAS at age 2 that contribute to ADHD, particularly at low to mid-levels.

Examining the relationship between birth weight and attention-deficit hyperactivity disorder diagnosis

Background

Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental condition that is prevalent in children worldwide. We evaluated the potential relationship between birth weight and ADHD using newly released data from the National Survey of Children's Health 2019-2020.

Methods

This population-based survey study used parent recollection data that were collected and submitted by 50 states and the District of Columbia to the National Survey of Children's Health database from the National Survey of Children's Health database. Those aged < 3 years and without birth weight or ADHD records were excluded. Children were stratified according to ADHD diagnosis and birth weight: very low birth weight (VLBW, < 1,500 g), low birth weight (LBW, 1,500-2,500 g), and normal birth weight (NBW, ≥ 2,500 g). Multivariable logistic regression was applied to examine the causal association between birth weight and ADHD while controlling for child and household characteristics.

Results

The final sample consisted of 60,358 children, of whom 6,314 (9.0%) were reported to have an ADHD diagnosis. The prevalence of ADHD was 8.7% in NBW children, 11.5% in LBW, and 14.4% in VLBW. Compared with NBW children, LBW children [adjusted odds ratio (aOR), 1.32 (95% CI, 1.03-1.68)], and VLBW children [aOR, 1.51 (95% CI, 1.06-2.15)] had a significantly higher risk of ADHD after adjusting all variables. These associations persisted in the male subgroups.

Conclusion and relevance

This study found that LBW and VLBW children were at a higher risk of ADHD.

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.

Multiple toxicity evaluations of perfluorooctane sulfonate on intact planarian Dugesia japonica

Perfluorooctane sulfonate (PFOS) is gaining widespread attention as a persistent organic pollutant with multiple mechanisms of toxicity. In this study, PFOS at different concentrations and different exposure times was used to evaluate the multiple toxicities on intact planarian Dugesia japonica. The proliferation of neoblasts, apoptosis, DNA damage and the expression levels of neuronal genes and the major genes of the Wnt pathway were effectively studied. The results demonstrated that the balance between proliferation and apoptosis of intact planarian cells was disrupted after PFOS exposure, which in turn affected tissue homeostasis and differentiation. PFOS exposure led to increased DNA damage and altered neuronal gene expression. In addition, PFOS exposure could down-regulate the expression of Wnt pathway genes, but the inhibition of the Wnt pathway by PFOS was time- and concentration-dependent. These findings suggest that PFOS has multiple toxic effects on planarians and may interfere with cell proliferation and neurodevelopment by affecting the key gene expression in the Wnt pathway, providing estimable information on the neurodevelopmental toxicity and ecotoxicity of PFOS toxicity in aquatic animals and environments.

Exposure to perfluoroalkyl and polyfluoroalkyl substances and estimated glomerular filtration rate in adults: a cross-sectional study based on NHANES (2017-2018)

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) may be important environmental risk factors affecting renal function. This study aimed to investigate the relationships between PFASs and estimated glomerular filtration rate (eGFR) in univariate exposure and multivariate co-exposure models of PFASs. A total of 1700 people over 18 years from National Health and Nutrition Examination Survey (NHANES) in 2017-2018 were selected as subjects to explore the relationships between eGFR and six PFASs (perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFUA), perfluorodecanoic acid (PFDeA), and perfluorohexane sulfonate (PFHxS)). First, multiple linear regression was used to estimate the association of each PFAS with eGFR, and the joint effect of PFAS mixtures was evaluated by Bayesian kernel machine regression (BKMR). Multiple linear regression analysis showed PFOS (β =  - 0.246, p = 0.026) and PFHxS (β = 0.538, p = 0.049) were significantly associated with eGFR in total population. In BKMR analysis, there was joint effect between PFOS and PFHxS for eGFR. And there were the joint effects of multiple PFAS on eGFR, especially the significant joint effect between PFHxS and PFDeA/PFNA/PFUA. Future cohort studies need to explore the association of multiple PFASs and health.

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.

Perfluorononanoic Acid Induces Neurotoxicity via Synaptogenesis Signaling in Zebrafish

Perfluorononanoic acid (PFNA), commonly used as an alternative polyfluorinated compound (PFC) of perfluorooctanoic acid (PFOA), has been widely detected in the aquatic environment. Previous ecotoxicological and epidemiological results suggested that some neurobehavioral effects were associated with PFC exposure; however, the ecological impacts and underlying neurotoxicity mechanisms remain unclear, particularly in aquatic organisms during sensitive, early developmental stages. In this study, zebrafish embryos were exposed to environmentally relevant concentrations of PFNA for 120 h, and the neurological effects of PFNA were comprehensively assessed using transcriptional, biochemical, morphological, and behavioral assays. RNA sequencing and advanced bioinformatics analyses predicted and characterized the key biological processes and pathways affected by PFNA exposure, which included the synaptogenesis signaling pathway, neurotransmitter synapse, and CREB signaling in neurons. Neurotransmitter levels (acetylcholine, glutamate, 5-hydroxytryptamine, γ-aminobutyric acid, dopamine, and noradrenaline) were significantly decreased in zebrafish larvae, and the Tg(gad67:GFP) transgenic line revealed a decreased number of GABAergic neurons in PFNA-treated larvae. Moreover, the swimming distance, rotation frequency, and activity degree were also significantly affected by PFNA, linking molecular-level changes to behavioral consequences.

Perfluorinated chemicals (PFOA) can, by interacting with highly brominated diphenyl ethers (PBDE 209) during a defined period of neonatal brain development, exacerbate neurobehavioural defects

Perfluorinated compounds (PFCs) and polybrominated diphenyl ethers (PBDEs) are ubiquitous persistent environmental compounds, present in humans and at higher levels in infants/children than in adults. This study shows that co-exposure to pentadecafluorooctanoic acid (PFOA) and 2,2',3,3',4,4',5,5',6,6'-decaBDE (PBDE 209) can significantly exacerbate developmental neurobehavioural defects. Neonatal male NMRI mice, 3 and 10 days old, were exposed perorally to PBDE 209 (1.4 or 8.0 μmol/kg bw), PFOA (1.4 or 14 μmol/kg bw), co-exposed to PBDE 209 and PFOA (at the given doses), or a vehicle (20% fat emulsion) and observed for spontaneous behaviour in a novel home environment when 2 and 4 months old. The behavioural defects observed included hyperactivity and reduced habituation indicating cognitive defects. This interaction appears most likely dependent on the presence of PBDE 209 and/or its metabolites together with PFOA, during a defined critical period of neonatal brain development, corresponding to the perinatal and newborn period in humans.

PFAS levels and exposure determinants in sensitive population groups

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants. The first exposure to PFAS occurs in utero, after birth it continues via breast milk, food intake, environment, and consumer products that contain these chemicals. Our aim was to identify determinants of PFAS concentrations in sensitive population subgroups- pregnant women and newborns.

METHODS

Nine European birth cohorts provided exposure data on PFAS in pregnant women (INMA-Gipuzkoa, Sabadell, Valencia, ELFE and MoBa; total N = 5897) or newborns (3xG study, FLEHS 2, FLEHS 3 and PRENATAL; total N = 940). PFOS, PFOA, PFHxS and PFNA concentrations were measured in maternal or cord blood, depending on the cohort (FLEHS 2 measured only PFOS and PFOA). PFAS concentrations were analysed according to maternal characteristics (age, BMI, parity, previous breastfeeding, smoking, and food consumption during pregnancy) and parental educational level. The association between potential determinants and PFAS concentrations was evaluated using multiple linear regression models.

RESULTS

We observed significant variations in PFAS concentrations among cohorts. Higher PFAS concentrations were associated with higher maternal age, primipara birth, and educational level, both for maternal blood and cord blood. Higher PFAS concentrations in maternal blood were associated with higher consumption of fish and seafood, meat, offal and eggs. In cord blood, higher PFHxS concentrations were associated with daily meat consumption and higher PFNA with offal consumption. Daily milk and dairy consumption were associated with lower concentrations of PFAS in both, pregnant women and newborns.

CONCLUSION

High detection rates of the four most abundant PFAS demonstrate ubiquitous exposure of sensitive populations, which is of concern. This study identified several determinants of PFAS exposure in pregnant women and newborns, including dietary factors, and these findings can be used for proposing measures to reduce PFAS exposure, particularly from dietary sources.

Perfluorooctanoic acid (PFOA) exposure in relation to the kidneys: A review of current available literature

Perfluorooctanoic acid is an artificial and non-degradable chemical. It is widely used due to its stable nature. It can enter the human body through food, drinking water, inhalation of household dust and contact with products containing perfluorooctanoic acid. It accumulates in the human body, causing potential harmful effects on human health. Based on the biodegradability and bioaccumulation of perfluorooctanoic acid in the human body, there are increasing concerns about the adverse effects of perfluorooctanoic acid exposure on kidneys. Research shows that kidney is the main accumulation organ of Perfluorooctanoic acid, and Perfluorooctanoic acid can cause nephrotoxicity and produce adverse effects on kidney function, but the exact mechanism is still unknown. In this review, we summarize the relationship between Perfluorooctanoic acid exposure and kidney health, evaluate risks more clearly, and provide a theoretical basis for subsequent research.

Schmidt R, N. Pearce E. Prenatal Exposure to Per- and Polyfluoroalkyl Substances, Maternal Thyroid Dysfunction, and Child Autism Spectrum Disorder

Autism spectrum disorder (ASD), with its high economic and societal costs, is a growing public health concern whose prevalence has risen steadily over the last two decades. Although actual increased incidence versus improved diagnosis remains controversial, the increased prevalence of ASD suggests non-inherited factors as likely contributors. There is increasing epidemiologic evidence that abnormal maternal thyroid function during pregnancy is associated with increased risk of child ASD and other neurodevelopmental disorders. Prenatal exposure to endocrine-disrupting chemicals such as per- and polyfluoroalkyl substances (PFAS) is known to disrupt thyroid function and can affect early brain development; thus, thyroid dysfunction is hypothesized to mediate this relationship. The concept of a potential pathway from prenatal PFAS exposure through thyroid dysfunction to ASD etiology is not new; however, the extant literature on this topic is scant. The aim of this review is to evaluate and summarize reports with regard to potential mechanisms in this pathway.

Photodegradation of per- and polyfluoroalkyl substances in water: A review of fundamentals and applications

Per- and polyfluoroalkyl substances (PFAS) are persistent, mobile, and toxic chemicals that are hazardous to human health and the environment. Several countries, including the United States, plan to set an enforceable maximum contamination level for certain PFAS compounds in drinking water sources. Among the available treatment options, photocatalytic treatment is promising for PFAS degradation and mineralization in the aqueous solution. In this review, recent advances in the abatement of PFAS from water using photo-oxidation and photo-reduction are systematically reviewed. Degradation mechanisms of PFAS by photo-oxidation involving the holes (h_vb⁺) and oxidative radicals and photo-reduction using the electrons (e_cb^-) and hydrated electrons (e_aq^-) are integrated. The recent development of innovative heterogeneous photocatalysts and photolysis systems for enhanced degradation of PFAS is highlighted. Photodegradation mechanisms of alternative compounds, such as hexafluoropropylene oxide dimer acid (GenX) and chlorinated polyfluorinated ether sulfonate (F-53B), are also critically evaluated. This paper concludes by identifying major knowledge gaps and some of the challenges that lie ahead in the scalability and adaptability issues of photocatalysis for natural water treatment. Development made in photocatalysts design and system optimization forges a path toward sustainable treatment of PFAS-contaminated water through photodegradation technologies.

Phytoremediation prospects of per- and polyfluoroalkyl substances: A review

Extensive use of per- and polyfluoroalkyl substances (PFASs) in various industrial activities and daily-life products has made them ubiquitous contaminants in soil and water. PFAS-contaminated soil acts as a long-term source of pollution to the adjacent surface water bodies, groundwater, soil microorganisms, and soil invertebrates. While several remediation strategies exist to eliminate PFASs from the soil, strong ionic interactions between charged groups on PFAS with soil constituents rendered these PFAS remediation technologies ineffective. Pilot and field-scale data from recent studies have shown a great potential of PFAS to bio-accumulate and distribute within plant compartments suggesting that phytoremediation could be a potential remediation technology to clean up PFAS contaminated soils. Even though several studies have been performed on the uptake and translocation of PFAS by different plant species, most of these studies are limited to agricultural crops and fruit species. In this review, the role of both aquatic and terrestrial plants in the phytoremediation of PFAS was discussed highlighting different mechanisms underlying the uptake of PFASs in the soil-plant and water-plant systems. This review further summarized a wide range of factors that influence the bioaccumulation and translocation of PFASs within plant compartments including both structural properties of PFASs and physiological properties of plant species. Even though phytoremediation appears to be a promising remediation technique, some limitations that reduced the feasibility of phytoremediation in the practical application have been emphasized in previous studies. Additional research directions are suggested, including advanced genetic engineering techniques and endophyte-assisted phytoremediation to upgrade the phytoremediation potential of plants for the successful removal of PFASs.

In utero exposure to perfluoroalkyl and polyfluoroalkyl substances and attention and executive function in the offspring: A study in the Danish National Birth Cohort

BACKGROUND

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are ubiquitous in the environment and accumulate in humans. PFAS are suspected to affect the neuropsychological function of children, but only few studies have evaluated the association with childhood attention and executive function.

OBJECTIVES

To investigate the association between intrauterine exposure to PFAS and offspring attention and executive function.

METHODS

A total of 1593 children from the Danish National Birth Cohort, born 1996-2003, were included. The levels of 16 PFAS were measured in maternal plasma during pregnancy. At 5 years of age, the Test of Everyday Attention for Children at Five (TEACh-5) and the Behavior Rating Inventory of Executive Function (BRIEF) were performed. TEACh-5 scores were standardized to a mean of 0 and standard deviation (SD) of 1. BRIEF scores were standardized to a mean of 50 and a SD of 10. The associations between levels of seven PFAS and TEACh-5 and BRIEF were examined by multivariable linear regression adjusted for potential confounders.

RESULTS

Perfluorooctane sulfonamide (PFOSA) was associated with poorer selective attention [standardized mean difference (95% confidence interval) -0.5 (-0.7, -0.3), highest versus lowest quartile]. Other PFAS were not clearly associated with selective attention, and we found no clear associations between PFAS exposure and sustained attention. For parent rated executive function, perfluorooctanoate (PFOA) was associated with poorer scores, standardized mean difference 3.8 (95% confidence interval 1.6, 6.0), highest versus lowest quartile. Regarding other PFAS, the associations were less clear. We found no clear associations between any PFAS and executive function rated by preschool teachers.

CONCLUSION

Intrauterine exposure to PFOSA was associated with poorer selective attention, while PFOA was associated with poorer executive function. Given the widespread nature of PFAS exposure, these findings may have public health implications, warranting further investigation.

Perfluorooctane sulfonates induces neurobehavioral changes and increases dopamine neurotransmitter levels in zebrafish larvae

It has been reported that exposure to perfluorooctane sulfonates (PFOS) causes behavioral abnormalities in zebrafish larvae, but the possible mechanisms underlying these changes remain unexplored. In this study, zebrafish embryos (2 h postfertilization, 2-hpf) were exposed to PFOS at different concentrations (0, 0.032, 0.32 and 3.2 mg/L) for 120 h. Developmental endpoints and the locomotion behavior of larvae were evaluated. Reactive oxygen species (ROS) levels, dopamine contents, several genes and proteins related to neurodevelopment and dopamine signaling were examined. Our results indicate that increased ROS levels in the zebrafish larvae heads may be causally associated with neurodevelopment damage. Meanwhile, brain-derived neurotrophic factor (BDNF) and alpha1-Tubulin (α1-Tubulin) protein contents were significantly increased, which may be a compensatory mechanism for the impaired central nervous system. PFOS-induced locomotor hyperactivity was observed in the first light phase and dark phase at the 0.32 and 3.2 mg/L of PFOS. Upregulation of dopamine-related genes tyrosine hydroxylase (th) and dopamine transporter (dat) associated with increased dopamine contents in the 3.2 mg/L of PFOS. In addition, protein expression of TH and DAT were noted at the 0.32 and 3.2 mg/L of PFOS concentrations. Our results suggested that PFOS induces neurobehavioral changes in zebrafish larvae, possibly by perturbing a dopamine signaling pathway. In addition, PFOS induced development damage, such as increased malformation rate and shorter body length.

Icariin attenuates perfluorooctane sulfonate-induced testicular toxicity by alleviating Sertoli cell injury and downregulating the p38MAPK/MMP9 pathway

Perfluorooctane sulfonate (PFOS) is widely recognized as causing Sertoli cell injury and testicular toxicity in males. Icariin is a flavonoid from Epimedium, which effectively improves spermatogenesis disturbance induced by several factors in clinic. However, it is unclear whether icariin improves PFOS-induced testicular toxicity. In vivo, fifty-two male mice were randomly separated into four groups: normal control group, model group, and low and high doses of icariin-treated groups, with 13 mice in each group. Except for the normal control group, the mice in the model group and icariin-treated groups were administered PFOS (10 mg kg-1) by gavage daily for 28 consecutive days, and concurrently treated with a diet containing different doses of icariin (0, 5 or 20 mg kg-1). In vitro, TM4 cells were treated with 150 μM PFOS to induce Sertoli cell injury, and were then utilized for icariin treatment. Our results demonstrated that icariin attenuated PFOS-induced testicular toxicity by increasing the testicular, epididymal and seminal vesicle weights, epididymal and seminal vesicle indices, sperm parameters, and seminiferous epithelium height. In addition, icariin improved the PFOS-induced blood-testis barrier (BTB) disruption by alleviating the Sertoli cell junctional injury, but without affecting Sertoli cell numbers in the testis of mice. Moreover, icariin increased the expression levels of tight junction proteins (ZO-1, Occludin and Claudin-11) and gap junction proteins (CX43 and p-CX43), and decreased the expression levels of p-p38MAPK and matrix metalloproteinase 9 (MMP9) both in vivo and in vitro. Furthermore, alleviation of the Sertoli cell injury by icariin exerted similar effects as SB203580 (an inhibitor of p38MAPK) in TM4 cells. This study revealed that icariin effectively reduces PFOS-induced testicular toxicity by alleviating the Sertoli cell injury and downregulating the p38MAPK/MMP9 pathway, indicating that icariin may be an attractive dietary supplement for the intervention of PFOS-induced testicular dysfunction.

Gestational Perfluoroalkyl Substance Exposure and DNA Methylation at Birth and 12 Years of Age: A Longitudinal Epigenome-Wide Association Study

BACKGROUND

DNA methylation alterations may underlie associations between gestational perfluoroalkyl substances (PFAS) exposure and later-life health outcomes. To the best of our knowledge, no longitudinal studies have examined the associations between gestational PFAS and DNA methylation.

OBJECTIVES

We examined associations of gestational PFAS exposure with longitudinal DNA methylation measures at birth and in adolescence using the Health Outcomes and Measures of the Environment (HOME) Study (2003-2006; Cincinnati, Ohio).

METHODS

We quantified serum concentrations of perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoate (PFNA), and perfluorohexane sulfonate (PFHxS) in mothers during pregnancy. We measured DNA methylation in cord blood (n=266) and peripheral leukocytes at 12 years of age (n=160) using the Illumina HumanMethylation EPIC BeadChip. We analyzed associations between log2-transformed PFAS concentrations and repeated DNA methylation measures using linear regression with generalized estimating equations. We included interaction terms between children's age and gestational PFAS. We performed Gene Ontology enrichment analysis to identify molecular pathways. We used Project Viva (1999-2002; Boston, Massachusetts) to replicate significant associations.

RESULTS

After adjusting for covariates, 435 cytosine-guanine dinucleotide (CpG) sites were associated with PFAS (false discovery rate, q<0.05). Specifically, we identified 2 CpGs for PFOS, 12 for PFOA, 8 for PFHxS, and 413 for PFNA; none overlapped. Among these, 2 CpGs for PFOA and 4 for PFNA were replicated in Project Viva. Some of the PFAS-associated CpG sites annotated to gene regions related to cancers, cognitive health, cardiovascular disease, and kidney function. We found little evidence that the associations between PFAS and DNA methylation differed by children's age.

DISCUSSION

In these longitudinal data, PFAS biomarkers were associated with differences in several CpGs at birth and at 12 years of age in or near genes linked to some PFAS-associated health outcomes. Future studies should examine whether DNA methylation mediates associations between gestational PFAS exposure and health. https://doi.org/10.1289/EHP10118.

Role of endocrine disrupting chemicals in children's neurodevelopment

Environmental stressors, like endocrine disrupting chemicals (EDC), are considered important contributors to the increased rates of neurodevelopmental dysfunctions. Considering the cumulative research on adverse neurodevelopmental effects associated with prenatal exposure to EDC, the purpose of this study was to review the available limited literature about the effects of postnatal exposure to EDC on child neurodevelopment and behaviour. Despite widespread children's exposure to EDC, there are a limited number of epidemiological studies on the association of this exposure with neurodevelopmental disorders, in particular in the postnatal period. The available research suggests that postnatal EDC exposure is related to adverse neurobehavioral outcomes in children; however the underlying mechanisms of action remain unclear. Timing of exposure is a key factor determining potential neurodevelopmental consequences, hence studying the impact of multiple EDC co-exposure in different vulnerable life periods could guide the identification of sensitive subpopulations. Most of the reviewed studies did not take into account sex differences in the EDC effects on children neurodevelopment. We believe that the inclusion of sex in the study design should be considered as the role of EDC on children neurodevelopment are likely sex-specific and should be taken into consideration when determining susceptibility and potential mechanisms of action.

Prenatal Exposure to Per- and Polyfluoroalkyl Substances and Facial Features at 5 Years of Age: A Study from the Danish National Birth Cohort

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are widespread persistent pollutants. Evidence regarding neurodevelopmental effects of PFAS have been mixed. The relation between PFAS exposure and anatomical markers that have been suggested to correlate with fetal brain development have not been studied.

OBJECTIVES

We investigated the association between prenatal PFAS exposures and three craniofacial features in children measured at 5 years of age.

METHODS

Measures of palpebral fissure length (PFL), philtrum groove, and upper-lip thickness were generated from standardized digital facial photographs from 656 children in the Danish National Birth Cohort. PFL was classified into two groups (shorter; normal), and the philtrum (grooved; smooth; normal) and upper-lip (thick; thin; normal) measures into three groups each. Six PFAS were measured in maternal plasma (median=8 gestational wk). Multinomial logistic regression was used to estimate the odds ratio (OR) and 95% confidence interval (CI) for each facial feature using the normal group as the reference according to log2-PFAS concentration (in nanograms per milliliter) or PFAS tertiles, adjusting for potential confounders, including maternal alcohol intake and smoking. Stratified analyses by maternal alcohol intake or child's sex were performed.

RESULTS

Prenatal exposure to each PFAS was associated with elevated odds for a shorter PFL, with the strongest association observed for perfluorodecanoic acid (PFDA; per doubling OR=2.02; 95% CI: 1.11, 3.70). Some nonlinear associations were found for philtrum measures: the second tertile of PFDA and perfluorononanoic acid were associated with grooved philtrum, whereas the second tertile of perfluoroheptane sulfonate with smooth philtrum. The associations between PFAS exposure and a shorter PFL were stronger among mothers who consumed alcohol in the first trimester, some sex-specific associations were noted for philtrum and upper-lip measures.

DISCUSSION

Prenatal PFAS exposures might influence fetal craniofacial development. A larger study is needed to replicate the potential modifying effects observed for alcohol exposure and to clarify whether associations of craniofacial markers observed reflect specific neurologic deficits. https://doi.org/10.1289/EHP9478.

The association between maternal perfluoroalkyl substances exposure and early attention deficit hyperactivity disorder in children: a systematic review and meta-analysis

Some studies have shown that maternal exposure to perfluoroalkyl substances (PFASs) may be associated with early attention deficit hyperactivity disorder (ADHD) in children. The purpose of this systematic review and meta-analysis is to verify this association by reviewing existing studies and to provide a strong basis for preventing ADHD. The researchers searched electronic databases such as PubMed, Science Direct, Scopus, Google Scholar, Web of Science, and Embase for all studies published before October 2020. Finally, we included nine articles for analysis. Our meta-analysis showed that maternal exposure to PFASs was not significantly associated with the prevalence rate of early childhood ADHD (perfluorooctanoic acid (PFOA), odds ratio (OR) = 1.00, 95% confidence interval (95% CI) = 0.75-1.25; perfluorooctane sulfonate (PFOS), OR = 1.01, 95% CI = 0.88-1.14; perfluorohexane sulfonate (PFHxS), OR = 1.08, 95% CI = 0.80-1.09; perfluorononanoic acid (PFNA), OR = 1.13, 95% CI = 0.99-1.28; perfluorodecanoic acid (PFDA), OR = 1.23, 95% CI = 0.15-2.32). Due to significant heterogeneity, we subsequently performed subgroup analysis and sensitivity analysis. Through subgroup analysis, we found that PFOS concentration of children's blood and the prevalence rate of early childhood ADHD were statistically positively correlated, and there was also a positive correlation between PFOS exposure and the prevalence rate of early childhood ADHD in the America. Moreover, there was also a statistically positive correlation between PFNA concentration in maternal blood and the prevalence rate of early childhood ADHD. Sensitivity analysis showed that the final results did not change much, the sensitivity was low, and the results were relatively stable. In conclusion, a causal relationship between maternal PFASs exposure and ADHD in children was unlikely. Among them, PFOS, PFNA, and ADHD might have positive associations worthy of further investigation.

Per- and Polyfluoroalkyl Substances (PFAS) in Integrated Crop-Livestock Systems: Environmental Exposure and Human Health Risks

Per- and polyfluoroalkyl substances (PFAS) are highly persistent synthetic organic contaminants that can cause serious human health concerns such as obesity, liver damage, kidney cancer, hypertension, immunotoxicity and other human health issues. Integrated crop–livestock systems combine agricultural crop production with milk and/or meat production and processing. Key sources of PFAS in these systems include firefighting foams near military bases, wastewater sludge and industrial discharge. Per- and polyfluoroalkyl substances regularly move from soils to nearby surface water and/or groundwater because of their high mobility and persistence. Irrigating crops or managing livestock for milk and meat production using adjacent waters can be detrimental to human health. The presence of PFAS in both groundwater and milk have been reported in dairy production states (e.g., Wisconsin and New Mexico) across the United States. Although there is a limit of 70 parts per trillion of PFAS in drinking water by the U.S. EPA, there are not yet regional screening guidelines for conducting risk assessments of livestock watering as well as the soil and plant matrix. This systematic review includes (i) the sources, impacts and challenges of PFAS in integrated crop–livestock systems, (ii) safety measures and protocols for sampling soil, water and plants for determining PFAS concentration in exposed integrated crop–livestock systems and (iii) the assessment, measurement and evaluation of human health risks related to PFAS exposure.

Prenatal exposure to persistent organic pollutants and metals and problematic child behavior at 3-5 years of age: a Greenlandic cohort study

High levels of persistent organic pollutants (POPs) and heavy metals are found in Arctic populations. POP and heavy metals are linked to impaired cognitive development. This study examined associations between prenatal POP and metals exposure and problematic child behavior using the Strength and Difficulties Questionnaire (SDQ). POPs and metals were measured in 102 pregnant Greenlandic women. During follow-up at 3–5 years, parents answered an assisted questionnaire including children’s SDQ scores. Associations were analyzed using linear and logistic regression analyses and adjusted for maternal plasma cotinine, educational level and age at delivery. In the adjusted analyses, the medium tertile of hexachlorobenzene (β = 3.06, p = 0.010), β-hexachlorocyclohexane (β = 3.58, p = 0.004) and trans-nonachlor (β = 2.06, p = 0.082) were positively associated with SDQ scores. The continuous cis-nonachlor (OR = 1.09, p = 0.079), dichloro-diphenyl-dichloroethylene (OR = 1.01, p = 0.077), trans-nonachlor (OR = 1.01, p = 0.091), and sum Organochlorine-Pesticides (OR = 1.00, p = 0.094) were positively associated with abnormal SDQ score and the continuous mirex (OR = 1.28, p = 0.096), oxychlordane (OR = 1.04, p = 0.066), and trans-nonachlor (OR = 1.02, p = 0.071) with abnormal hyperactivity score. We found no consistent evidence of associations between polychlorinated biphenyls, perfluoroalkylated substances and heavy metals and problematic behavior. Prenatal organochlorine pesticide exposure associated significantly with problematic behavior in 3–5 year old children.

Engineering human liver fatty acid binding protein for detection of poly- and perfluoroalkyl substances

Per- and polyfluoroalkyl substances (PFAS) are a large group of synthetic fluorinated chemicals with surface active and water-repellent properties. The combination of wide-spread use in numerous consumer and industrial products and extended biological half-lives arising from strong carbon-fluorine bonds has led to significant accumulation of PFAS in humans. As most human interaction with PFAS comes from ingestion, it is important to be able to detect PFAS in drinking water as well as in agricultural water. Here we present an approach to designing a fluorescence-based biosensor for the rapid detection of PFAS based on human liver fatty acid binding protein (hLFABP). Introduction of solvatochromic fluorophores within the ligand binding pocket (L50) allowed for intrinsic detection of perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), and perfluorohexanesulfonic acid (PFHxS) via blue-shifts in fluorescence emission spectra. Initially, a single tryptophan mutation (L50W) was found to be able to detect PFOA with a limit of detection (LOD) of 2.8 ppm. We improved the sensitivity of the biosensor by exchanging tryptophan for the thiol reactive fluorophore, acrylodan. The acrylodan conjugated C69S/F50C hLFABP variant is capable of detecting PFOA, PFOS, and PFHxS in PBS with LODs of 112 ppb, 345 ppb, and 1.09 ppm, respectively. The protein-based sensor is also capable of detecting these contaminants at similar ranges in spiked environmental water samples, including samples containing an interfering anionic surfactant sodium dodecyl sulfate. Overall, this study demonstrates engineered hLFABP is a useful platform for detection of PFAS in environmental water samples and highlights its ease of use and versatility in field applications.

Prenatal and childhood exposure to per- and polyfluoroalkyl substances (PFAS) and child executive function and behavioral problems

Early life exposure to per- and polyfluoroalkyl substances (PFAS) may adversely impact neurodevelopment, but epidemiological findings are inconsistent. In the Project Viva pre-birth cohort, we examined associations of prenatal and childhood PFAS plasma concentrations with parent and teacher assessments of children's behavior problems [Strengths and Difficulties Questionnaire (SDQ)] and executive function abilities [Behavior Rating Inventory of Executive Function (BRIEF)] at age 6-10 years (sample sizes 485-933). PFAS concentrations in pregnant Project Viva mothers (in 1999-2002) and children at ages 6-10 (in 2007-10) were similar to concentrations at similar time points in women and children in the nationally representative U.S. National Health and Nutrition Examination Survey. We observed no consistent associations of prenatal PFAS concentrations with behavior or executive function. Childhood concentrations of perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorononanoate (PFNA) and perfluorodecanoate (PFDA) were associated with higher parent-rated SDQ Total Difficulties scores (mean = 6.7, standard deviation (SD) = 4.9), suggesting greater behavioral problems (top (Q4) versus bottom (Q1) quartile PFOA: 1.5, 95% confidence interval (CI): 0.3, 2.7; PFOS: 1.4, 95% CI: 0.3, 2.5; PFHxS: 1.2, 95% CI: 0.1, 2.3; PFNA: 1.2, 95% CI: 0.1, 2.2; PFDA: 1.1, 95% CI: 0.0, 1.1); teacher-rated SDQ scores did not show associations. Higher childhood PFOS was associated with higher (indicating more problems) parent-rated BRIEF General Executive Composite (GEC) scores (standardized to mean = 50, SD = 10) (Q4 vs. Q1: 2.4, 95% CI: 0.2, 4.6), while teacher BRIEF GEC scores indicated more problems among children with higher PFHxS (Q4 vs. Q1: 3.5, 95% CI: -0.8, 6.3). There were no consistent patterns of sexual dimorphism in associations. In a cohort of U.S. children, we observed cross-sectional associations of childhood PFAS concentrations with greater behavioral and executive function problems, but no consistent associations with prenatal PFAS.

Selective Removal of Perfluorobutyric Acid Using an Electroactive Ion Exchanger Based on Polypyrrole@Iron Oxide on Carbon Cloth

Perfluorobutyric acid (PFBA) is one type of perfluoroalkyl and polyfluoroalkyl substances (PFASs) and is widely used as an industrial compound. The removal of PFBA has attracted considerable scientific interests in recent decades because it causes environmental pollution and human diseases. Currently, the adsorption method has been used commonly to remove PFASs from wastewater. However, it is usually limited by the inevitable "secondary waste" produced in this treatment process. In this work, PFBA can be effectively removed by synergistic electrical switching ion exchange (ESIX) and a new type of nanostructured ion exchanger. Herein, the nanostructured ion exchanger has been designed and synthesized by coating a polypyrrole (PPy)@Fe₂O₃ nanoneedle on carbon cloth (PPy@Fe₂O₃ NN-CC). Results show that the PPy@Fe₂O₃ NN-CC nanocomposite enhances ion exchange speed and efficiency, which ensures its high adsorption capacity and rapid regeneration property, thereby reducing secondary waste. Moreover, ESIX based on the PPy@Fe₂O₃ NN-CC nanocomposite has high selectivity for adsorption of PFBA over other common anions in water, such as Cl^-, SO₄^2-, and NO₃^-.

Serum per- and polyfluoroalkyl substance (PFAS) concentrations and predictors of exposure among pregnant African American women in the Atlanta area, Georgia

Exposure to per- and polyfluoroalkyl substances (PFAS) has been associated with adverse health outcomes, especially when exposure occurs within sensitive time windows such as the pre- and post-natal periods and early childhood. However, few studies have focused on PFAS exposure distribution and predictors in pregnant women, especially among African American women. We quantified serum concentrations of the four most common PFAS collected in all 453 participants and an additional 10 PFAS in 356 participants who were pregnant African American women enrolled from 2014 to 2018 in Atlanta, Georgia, and investigated the sociodemographic predictors of exposure. Additional home environment and behavior predictors were also examined in 130 participants. Perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) were detected in >95% of the samples with PFOS having the highest concentrations (geometric mean (GM) 2.03 ng/mL). N-Methyl perfluorooctane sulfonamido acetic acid (NMeFOSAA), perfluoropentanoic acid (PFPeA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA) were found in 40-50% of the samples, whereas the detection frequencies for the other six PFAS were below 15%. When compared to National Health and Nutrition Examination Survey (NHANES) participants matching sex, race, and age with this study, our results showed similar concentrations of most PFAS, but higher concentrations of PFHxS (GM 0.99 ng/mL in this study; 0.63 and 0.4 ng/mL in NHANES, 2014-2015 and 2016-2017 cycles). A decline in concentrations over the study period was found for most PFAS but not PFPeA. In adjusted models, education, sampling year, parity, BMI, tobacco and marijuana use, age of house, drinking water source, and cosmetic use were significantly associated with serum PFAS concentrations. Our study reports the first PFAS exposure data among pregnant African American women in the Atlanta area, Georgia. The identified predictors will facilitate the setting of research priorities and enable development of exposure mitigation strategies.

Prenatal exposure to per- and polyfluoroalkyl substances and cognitive development in infancy and toddlerhood

BACKGROUND/OBJECTIVE

Per- and polyfluoroalkyl substances (PFAS) have neurobehavioral toxicity in experimental studies. Evidence on associations between prenatal PFAS exposure and child's cognitive development is inconsistent partly due to differences in assessment time points and tools. We examined associations of prenatal maternal serum PFAS concentrations with child's cognitive development assessed at multiple time points in infancy and toddlerhood.

METHODS

We included 140 mother-child pairs from MARBLES (Markers of Autism Risk in Babies - Learning Early Signs), a longitudinal cohort of children with a first degree relative who was diagnosed with autism spectrum disorder followed from birth. Study children's cognitive development was assessed at 6, 12, 24, and 36 months of age using the Mullen Scales of Early Learning (MSEL) which provides an overall Early Learning Composite (normative mean of 100 and SD of 15) and four subscales (i.e., fine motor, visual reception, receptive language, and expressive language abilities; normative mean of 50 and SD of 10). Nine PFAS were quantified in maternal serum collected during pregnancy. We examined associations of log 2-transformed prenatal maternal serum PFAS concentrations with the MSEL Composite and each of the subscale scores at each time point as well as longitudinal changes in the scores over the four time points. We also classified trajectories into low- and high-score groups and fit Poisson regression models to estimate associations expressed as relative risks (RR).

RESULTS

Among six PFAS detected in more than 60% of the samples, prenatal maternal serum perfluorooctanoate (PFOA) was inversely associated with child's Composite score at 24 months (β = -5.22, 95% CI: -8.27, -2.17) and 36 months of age (β = -5.18, 95% CI: -9.46, -0.91), while other five PFAS were not strongly associated with Composite score at any time points. When assessing longitudinal changes in the scores over the four time points, PFOA was associated with trajectories having a negative slope for Composite scores and all four subscales. When examining trajectories of the scores between low- and high-score groups, PFOA was associated with having lower and/or decreasing Composite scores (RR = 1.49, 95% CI: 1.09, 2.03).

CONCLUSIONS

Prenatal PFOA appears to adversely affect child's cognitive development in toddlerhood in this study population. Because a large fraction of MARBLES children is at risk for atypical development, population-based studies are needed to confirm our findings.

Environmental toxicants in the brain: A review of astrocytic metabolic dysfunction

Exposure to environmental toxicants is linked to long-term adverse outcomes in the brain and involves the dysfunction of glial and neuronal cells. Astrocytes, the most numerous cell type, are increasingly implicated in the pathogenesis of many diseases of the central nervous system, including neurodegenerative diseases. Astrocytes are critical for proper brain function in part due to their robust antioxidant and unique metabolic capabilities. Additionally, astrocytes are positioned both at the blood-brain barrier, where they are the primary responders to xenobiotic penetrance of the CNS, and at synapses where they are in close contact with neurons and synaptic machinery. While exposure to several classes of environmental toxicants, including chlorinated and fluorinated compounds, and trace metals, have been implicated in neurodegenerative diseases, their impact on astrocytes represents an important and growing field of research. Here, we review existing literature focused on the impact of a range of synthetic compounds on astrocytic function. We focus specifically on perturbed metabolic processes in response to these compounds and consider how perturbation of these pathways impacts disease pathogenesis.

Prenatal Exposure to Endocrine-Disrupting Chemicals and Subsequent Brain Structure Changes Revealed by Voxel-Based Morphometry and Generalized Q-Sampling MRI

Previous studies have indicated that prenatal exposure to endocrine-disrupting chemicals (EDCs) can cause adverse neuropsychiatric disorders in children and adolescents. This study aimed to determine the association between the concentrations of prenatal EDCs and brain structure changes in teenagers by using MRI. We recruited 49 mother–child pairs during the third trimester of pregnancy, and collected and examined the concentration of EDCs—including phthalate esters, perfluorochemicals (PFCs), and heavy metals (lead, arsenic, cadmium, and mercury)—in maternal urine and/or serum. MRI voxel-based morphometry (VBM) and generalized q-sampling imaging (GQI) mapping—including generalized fractional anisotropy (GFA), normalized quantitative anisotropy (NQA), and the isotropic value of the orientation distribution function (ISO)—were obtained in teenagers 13–16 years of age in order to find the association between maternal EDC concentrations and possible brain structure alterations in the teenagers’ brains. We found that there are several specific vulnerable brain areas/structures associated with prenatal exposure to EDCs, including decreased focal brain volume, primarily in the frontal lobe; high frontoparietal lobe, temporooccipital lobe and cerebellum; and white matter structural alterations, which showed a negative association with GFA/NQA and a positive association with ISO, primarily in the corpus callosum, external and internal capsules, corona radiata, superior fronto-occipital fasciculus, and superior longitudinal fasciculus. Prenatal exposure to EDCs may be associated with specific brain structure alterations in teenagers.

Prenatal exposure to per- and polyfluoroalkyl substances (PFAS) and neurobehavior in US children through 8 years of age: The HOME study

BACKGROUND

Studies of prenatal per- and polyfluoroalkyl substances (PFAS) and attention deficit hyperactivity disorder (ADHD)-related behaviors in children are inconsistent.

OBJECTIVES

To examine associations between maternal serum PFAS concentrations and child behavior in 241 mother-child dyads within the Health Outcomes and Measures of the Environment (HOME) Study.

METHODS

We quantified perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), and perfluorononanoate (PFNA) in maternal serum collected during pregnancy or at delivery. We evaluated a total of 17 outcomes of child behavior using the Behavioral Assessment System for Children-2 (BASC-2) at 5 and 8 years (n = 240) and ADHD diagnostic symptoms and criteria with the Diagnostic Interview Schedule for Children-Young Child (DISC-YC) at 5 years (n = 190). We used linear mixed models and logistic regression with generalized estimating equations to assess associations between PFAS and continuous or dichotomous "at risk" BASC-2 scores; negative binomial regression to calculate incident rate ratios for counts of ADHD symptoms; and Poisson regression with robust standard errors to calculate relative risks of meeting ADHD diagnostic criteria.

RESULTS

Each ln-unit increase in PFOS, PFHxS, and PFNA was associated with higher BASC-2 scores and increased odds of "at-risk" scores for externalizing behaviors, including hyperactivity (PFOS: odds ratio [OR] 2.7, 95% confidence interval [CI] 1.2, 5.9; PFHxS: OR 2.5, 95% CI 1.5, 4.3; PFNA: OR 3.2, 95% CI 1.3, 8.0). PFHxS was also associated with internalizing problems (OR 2.0, 95% CI 1.1, 3.4) and somatization (OR 2.2, 95% CI 1.2, 4.0). PFOS and PFNA were significantly associated with 50-80% more DISC-YC symptoms and diagnostic criteria related to hyperactive-impulsive type ADHD. Prenatal PFNA was associated with increased risk of any-type ADHD.

CONCLUSIONS

Prenatal PFOS and PFNA were consistently associated with measures related to hyperactive-impulsive type ADHD across two validated assessment instruments. PFHxS was associated with increased problems with both externalizing and internalizing behaviors. No associations were noted between PFOA and child neurobehavior.

Rapid Zebrafish Behavioral Profiling Assay Accelerates the Identification of Environmental Neurodevelopmental Toxicants

Rapid and cost-effective in vivo assays to screen potential environmental neurodevelopmental toxicants are necessary to address the limitations of in vitro platforms, such as the inability to fully recapitulate the developmental and physiological processes of whole organisms. In the present study, a rapid zebrafish behavioral profiling assay was developed to characterize the neurodevelopmental effects of environmental substances by quantitatively evaluating multiple spontaneous movement features of zebrafish embryos. This video analysis-based assay automatically segmented every embryo and thus was able to accurately quantify spontaneous movement features, including frequency, duration, intensity, interval, and the number of continuous movements. When tested with eight environmental substances known to be neurodevelopmental toxicants, such as chlorpyrifos and bisphenol A, the assay successfully captured frequency alterations that were well-documented in previous studies while also providing additional information. Using an optimized procedure, we further assessed 132 potential neurotoxins that spanned a wide range of molecular targets, many of which were previously detected in environmental waterbodies. The distinct altered behavioral barcodes indicated that the spontaneous movement was impacted by diverse neuroactive substances, and the effects could be effectively evaluated with the developed assay. The web-based tool, named EMAnalysis, is further provided at http://www.envh.sjtu.edu.cn/zebrafish_contraction.jsp. Thus, this assay provides an efficient platform to accelerate the pace of neurotoxic environmental contaminant discoveries.

Perfluoroalkyl Substance Exposure and the BDNF Pathway in the Placental Trophoblast

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants that have become globally ubiquitous in humans and the environment. In utero PFAS exposure is associated with neurodevelopmental effects; however, the mechanism is poorly understood. Brain-derived neurotrophic factor (BDNF) signaling is critical to fetal neurodevelopment during pregnancy and maintains important regulatory roles later in life. This study aims to characterize placental BDNF signaling and investigate whether PFAS exposure disrupts the signaling pathway in placental trophoblast cells.

METHODS

The expression and localization of BDNF receptors-p75^NTR and TrkB-in first trimester and term human placentas and trophoblast cells were investigated by immunofluorescence staining. To assess the effects of PFAS exposure on the BDNF pathway, BeWo cells were treated with PFAS mixtures that mimicked blood levels in a highly exposed population and major PFAS compounds in the mixture at 0.01, 0.1, 1, and 10 µM concentrations. Changes in pro-BDNF levels and phosphorylation of TrkB receptors were examined by Western blot.

RESULTS

In first trimester human placentas, TrkB and p75^NTR receptors were primarily localized to syncytiotrophoblast and cytotrophoblast cells. At term, TrkB and p75^NTR receptors were primarily observed in the placental villous stroma. TrkB receptor staining in trophoblasts was reduced at term, while p75^NTR receptor staining was negative. TrkB receptors were confined to the nuclear and perinuclear spaces, and phosphorylation occurred at the Tyr816 residue in BeWo cells. Exposure to PFOS, PFOA, PFBS, and the six-PFAS mixture did not significantly affect BDNF levels or activation (phosphorylation) of TrkB. Treating cells with 1 μM and 10 μM of PFNA resulted in increased TrkB phosphorylation compared to unexposed controls, but BDNF levels were unchanged.

CONCLUSIONS

BDNF receptors are present in different regions of human placental villi, indicating diverse functions of BDNF signaling in placental development. Our findings suggest that the BDNF pathway in placental trophoblast cells is not disrupted by exposures to PFOS, PFOA, PFBS, and a PFAS mixture, but may be affected by PFNA exposures. Further investigation is needed on how PFAS affects other critical signaling pathways during fetal neurodevelopment.

Exposure to Perfluoroalkyl Substances During Pregnancy and Fetal BDNF Level: A Prospective Cohort Study

BACKGROUND

Humans are widely exposed to environmental perfluoroalkyl substances (PFAS), which may affect fetal neurodevelopment. Brain-derived neurotrophic factor (BDNF) is an important factor in neurodevelopment, but its role in PFAS-induced neurotoxicity is unclear. We investigated the association between prenatal PFAS exposure and fetal BDNF level in the umbilical cord blood in a large prospective cohort.

METHODS

A total of 725 pregnant women who participated in the Shanghai Birth Cohort were included. 10 PFAS were measured by high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS-MS) in the plasma samples of early pregnancy. The BDNF level was determined by ELISA. The concentration of total mercury (Hg) in the umbilical cord blood was tested by cold vapor atomic absorption spectrometry (AAS) and included as a main confounder, along with other covariates. Multiple linear regression was used to explore the associations between PFAS concentrations and BDNF level. Quantile-based g-computation was applied to explore the joint and independent effects of PFAS on BDNF level.

RESULTS

The mean BDNF level in the total population was 10797 (±4713) pg/ml. Male fetuses had a higher level than female fetuses (P<0.001). A significant positive association was observed between PFHxS and BDNF level after adjusting for potential confounders [β=1285 (95% CI: 453, 2118, P=0.003)]. No association was observed between other PFAS congeners and BDNF level. Results of the mixed exposure model showed that the joint effects of PFAS mixture were not associated with BDNF [β=447 (95% CI: -83, 978, P=0.10)], while the positive association with PFHxS exposure remained significant after controlling for other PFAS [β=592 (95% CI: 226, 958, P=0.002)]. The above associations were more prominent in male [β=773 (95% CI: 25, 1520, P= 0.04)] than female fetuses [β=105 (95% CI: -791, 1002, P= 0.82)] for the mixed effects.

CONCLUSIONS

Prenatal exposure to PFHxS was associated with an increased BDNF level in the umbilical blood, especially in male fetuses.

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

DISCUSSION

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

Prenatal exposure to perfluoroalkyl substances and behavioral difficulties in childhood at 7 and 11 years

BACKGROUND

Perfluoroalkyl substances (PFAS) are suggested to interfere with thyroid hormone during pregnancy and influence fetal neurodevelopment. Epidemiological evidence regarding behavioral difficulties in childhood associated with prenatal PFAS exposure has been inconclusive.

OBJECTIVE

We evaluated the association between prenatal PFAS exposure and behavioral difficulties at 7 and 11 years, and investigated the potential mediating role of maternal thyroid hormones.

METHODS

Using pooled samples in the Danish National Birth Cohort established between 1996 and 2002, we estimated the associations between concentrations of six types of PFAS in maternal plasma (median, 8 gestational weeks) and child behavioral assessments from the Strength and Difficulties Questionnaire (SDQ), reported by parents at 7 years (n = 2421), and by parents (n = 2070) and children at 11 years (n = 2071). Behavioral difficulties were defined as having a composite SDQ score above the 90th percentile for total difficulties and externalizing or internalizing behaviors. We used logistic regression to estimate the adjusted Odds Ratio (OR) by doubling increase of prenatal PFAS (ng/ml). The possible mediating effect of maternal thyroid function classified based on thyroid stimulating hormone (TSH) and free thyroxine (fT4) levels were evaluated.

RESULTS

Prenatal perfluorononanoic acid (PFNA) was consistently associated with total and externalizing behavioral difficulties in all three SDQ measures reported by parents (OR = 1.40, 95% CI: 1.14-1.73 for age 7; OR = 1.27, 95% CI: 1.05-1.53 for age 11) or children (OR = 1.32, 95% CI: 1.11-1.58) while no consistent associations were observed for other types of PFAS. A small magnitude of natural indirect effects via maternal thyroid dysfunction (ORs ranged from 1.01 to 1.03) of several PFAS were observed for parent-reported total and externalizing behaviors at 7 years only.

DISCUSSION

Prenatal PFNA exposure was associated with externalizing behavioral difficulties in childhood in repeated SDQ measures at 7 and 11 years. The slight mediating effects of maternal thyroid hormones in early gestation warrant further evaluation.

Review: Evolution of evidence on PFOA and health following the assessments of the C8 Science Panel

BACKGROUND

The C8 Science Panel was composed of three epidemiologists charged with studying the possible health effects of PFOA in a highly exposed population in the mid-Ohio Valley. The Panel determined in 2012 there was a 'probable link' (i.e., more probable than not based on the weight of the available scientific evidence) between PFOA and high cholesterol, thyroid disease, kidney and testicular cancer, pregnancy-induced hypertension, and ulcerative colitis.

OBJECTIVE

Here, former C8 Science Panel members and collaborators comment on the PFOA literature regarding thyroid disorders, cancer, immune and auto-immune disorders, liver disease, hypercholesterolemia, reproductive outcomes, neurotoxicity, and kidney disease. We also discuss developments regarding fate and transport, and pharmacokinetic models, and discuss causality assessment in cross-sectional associations among low-exposed populations.

DISCUSSION

For cancer, the epidemiologic evidence remains supportive but not definitive for kidney and testicular cancers. There is consistent evidence of a positive association between PFOA and cholesterol, but no evidence of an association with heart disease. There is evidence for an association with ulcerative colitis, but not for other auto-immune diseases. There is good evidence that PFOA is associated with immune response, but uneven evidence for an association with infectious disease. The evidence for an association between PFOA and thyroid and kidney disease is suggestive but uneven. There is evidence of an association with liver enzymes, but not with liver disease. There is little evidence of an association with neurotoxicity. Suggested reductions in birthweight may be due to reverse causality and/or confounding. Fate and transport models and pharmacokinetic models remain central to estimating past exposure for new cohorts, but are difficult to develop without good historical data on emissions of PFOA into the environment.

CONCLUSION

Overall, the epidemiologic evidence remains limited. For a few outcomes there has been some replication of our earlier findings. More longitudinal research is needed in large populations with large exposure contrasts. Additional cross-sectional studies of low exposed populations may be less informative.

Effects of different variables on photodestruction of perfluorooctanoic acid in self-assembled micelle system

Perfluoroalkyl substance (PFAS) is a class of anionic surfactants with superior stability in the environment. Due to the harmful health effect, PFASs have been listed as the priority controlled pollutants. Our recent study had developed a cationic surfactant induced ternary self-assembled micelle system to effectively degrade PFASs. In this study, using perfluorooctanoic acid (PFOA) as the model pollutant, we further investigated the effects of different variables on the degradation processes. According to the results of laser flash photolysis and dynamic light scattering, the degradation of PFOA was positively correlated with the chain length of the surfactants. While for double-chain surfactant, the steric effect might hinder the reaction. Our results also indicated that in the presence of high concentration of NaCl, the electrostatic attraction between Cl^- and the positively charged micelle made the micelle structure loose and thus slightly reduced the degradation efficiency. Similarly, the presence of NOM could also affect the degradation process via regulating the micelle structure. Furthermore, the optimal degradation efficiency for PFOA was obtained at neutral pH by the compromise of hydrated electron yield and self-assembled micelle structure. This composite showed good adaptability under ambient conditions and would have great potential for treatment of industrial PFAS containing wastewater, e.g., in the ternary micelle system, 18.95 mg L^-1 PFOA could be completely degraded within 8 h without any pretreatments.

A framework for assessing the impact of chemical exposures on neurodevelopment in ECHO: Opportunities and challenges

The Environmental influences on Child Health Outcomes (ECHO) Program is a research initiative funded by the National Institutes of Health that capitalizes on existing cohort studies to investigate the impact of early life environmental factors on child health and development from infancy through adolescence. In the initial stage of the program, extant data from 70 existing cohort studies are being uploaded to a database that will be publicly available to researchers. This new database will represent an unprecedented opportunity for researchers to combine data across existing cohorts to address associations between prenatal chemical exposures and child neurodevelopment. Data elements collected by ECHO cohorts were determined via a series of surveys administered by the ECHO Data Analysis Center. The most common chemical classes quantified in multiple cohorts include organophosphate pesticides, polychlorinated biphenyls, polybrominated diphenyl ethers, environmental phenols (including bisphenol A), phthalates, and metals. For each of these chemicals, at least four ECHO cohorts also collected behavioral data during infancy/early childhood using the Child Behavior Checklist. For these chemicals and this neurodevelopmental assessment (as an example), existing data from multiple ECHO cohorts could be pooled to address research questions requiring larger sample sizes than previously available. In addition to summarizing the data that will be available, the article also describes some of the challenges inherent in combining existing data across cohorts, as well as the gaps that could be filled by the additional data collection in the ECHO Program going forward.

Neurotoxic effects of lactational exposure to perfluorooctane sulfonate on learning and memory in adult male mouse

The present study aims to examine the effect of early lactational perfluorooctane sulfonate (PFOS) exposures on learning and memory in male mice and reveal the underlying mechanisms involved. PFOS solution was orally administered to dams from the postpartum days 1-14, so that pups would be exposed through breast milk. At 8-10 weeks of age, we performed object location test (OLT), object recognition test (ORT), and pairwise visual discrimination (VD) task. We also performed in vivo microdialysis, and mRNA and protein analysis of genes responsible for hippocampal development and function. In both OLT and ORT, the performance of mice in the PFOS-exposed group was significantly lower than those in the control group. In the VD task, the PFOS-exposed group learned significantly slower than the control group. Concentrations of glutamate and gamma-aminobutyric acid in the dorsal hippocampus were significantly higher in the PFOS-exposed group than in the control group. No notable differences were shown in our mRNA and protein studies. The present study showed that lactational PFOS exposure has a profound, long-lasting neurotoxic effect in the hippocampus and consequently leads to learning and memory deficits.

Calcium signaling as a possible mechanism behind increased locomotor response in zebrafish larvae exposed to a human relevant persistent organic pollutant mixture or PFOS

Persistent organic pollutants (POPs) are widespread in the environment and their bioaccumulation can lead to adverse health effects in many organisms. Previously, using zebrafish as a model vertebrate, we found larvae exposed to a mixture of 29 POPs based on average blood levels from the Scandinavian population showed hyperactivity, and identified perfluorooctanesulfonic acid (PFOS) as the driving agent for the behavioral changes. In order to identify possible mechanisms, we exposed zebrafish larvae from 6 to 96 h post fertilization to the same mixture of POPs in two concentrations or a single PFOS exposure (0.55 and 3.83 μM) and performed behavioral tests and transcriptomics analysis. Behavioral alterations of exposed zebrafish larvae included hyperactivity and confirmed previously reported results. Transcriptomics analysis showed upregulation of transcripts related to muscle contraction that is highly regulated by the availability of calcium in the sarcoplasmic reticulum. Ingenuity pathway analysis showed that one of the affected pathways in larvae exposed to the POP mixture and PFOS was calcium signaling via the activation of the ryanodine receptors (RyR). Functional analyses with RyR inhibitors and behavioral outcomes substantiate these findings. Additional pathways affected were related to lipid metabolism in larvae exposed to the lower concentration of PFOS. By using omics technology, we observed that the altered behavioral pattern in exposed zebrafish larvae may be controlled directly by mechanisms affecting muscle function rather than via mechanisms connected to neurotoxicity.