No association between maternal and child PFAS concentrations and repeated measures of ADHD symptoms at age 2½ and 5 years in children from the Odense Child Cohort

Regrettable Substitutes and the Brain: What Animal Models and Human Studies Tell Us about the Neurodevelopmental Effects of Bisphenol, Per- and Polyfluoroalkyl Substances, and Phthalate Replacements

In recent decades, emerging evidence has identified endocrine and neurologic health concerns related to exposure to endocrine-disrupting chemicals (EDCs), including bisphenol A (BPA), certain per- and polyfluoroalkyl compounds (PFASs), and phthalates. This has resulted in consumer pressure to remove these chemicals from the market, especially in food-contact materials and personal care products, driving their replacement with structurally or functionally similar substitutes. However, these "new-generation" chemicals may be just as or more harmful than their predecessors and some have not received adequate testing. This review discusses the research on early-life exposures to new-generation bisphenols, PFASs, and phthalates and their links to neurodevelopmental and behavioral alterations in zebrafish, rodents, and humans. As a whole, the evidence suggests that BPA alternatives, especially BPAF, and newer PFASs, such as GenX, can have significant effects on neurodevelopment. The need for further research, especially regarding phthalate replacements and bio-based alternatives, is briefly discussed.

Prenatal exposure to per- and polyfluoroalkyl substances and child behavioral problems

BACKGROUND

Prenatal exposure to per- and polyfluoroalkyl substances (PFAS) may adversely affect child behaviors; however, findings of epidemiologic studies are inconsistent. We examined prenatal PFAS exposure in association with child behavioral problems.

METHODS

Participants were 177 mother-child pairs from MARBLES (Markers of Autism Risk in Babies - Learning Early Signs), a cohort with elevated familial likelihood of autism spectrum disorder (ASD). We quantified nine PFAS in maternal serum (1-3 samples per mother) collected from the 1st to 3rd trimesters of pregnancy. Child behavioral problems were assessed at 3 years of age using the Child Behavior Checklist (CBCL), developed to test for various behavioral problems of children. We examined associations of the CBCL scores with individual PFAS concentrations and with their mixture using negative binomial regression and weighted quantile sum regression models.

RESULTS

Higher prenatal perfluorononanoate (PFNA) concentrations were associated with higher scores of externalizing problems [β = 0.16, 95% CI (0.01, 0.32)] and aggressive behavior [β = 0.17 (0.01, 0.32)]. Higher PFNA, perfluorooctane sulfonate (PFOS), and perfluorodecanoate (PFDA) were associated with higher scores of sleep problems [β = 0.34 (0.15, 0.54) for PFNA, β = 0.20 (0.02, 0.37) for PFOS, and β = 0.19 (0.00, 0.37) for PFDA]. No significant associations observed for typically developing children, whereas PFOS, PFNA, and PFDA were associated with several behavioral problems among children diagnosed with ASD or other neurodevelopmental concerns. Exposure to a mixture of PFAS was associated with higher scores of sleep problems and aggressive behavior, mostly contributed by PFNA and PFDA.

CONCLUSIONS

Our study showed that prenatal exposure to some PFAS could increase child behavioral problems at 3 years of age. However, our results should be interpreted with caution because we relied on data from a cohort with increased familial likelihood of ASD and thereby had more behavioral problems.

Exploring the Potential Link between PFAS Exposure and Endometrial Cancer: A Review of Environmental and Sociodemographic Factors

This exploratory narrative review paper delves into the intricate interplay between per- and polyfluoroalkyl substances (PFAS) exposure, sociodemographic factors, and the influence of stressors in the context of endometrial cancer. PFAS, ubiquitous environmental contaminants notorious for their persistence in the ecosystem, have garnered attention for their potential to disrupt endocrine systems and provoke immune responses. We comprehensively examine the various sources of PFAS exposure, encompassing household items, water, air, and soil, thus shedding light on the multifaceted routes through which individuals encounter these compounds. Furthermore, we explore the influence of sociodemographic factors, such as income, education, occupation, ethnicity/race, and geographical location and their relationship to endometrial cancer risk. We also investigated the role of stress on PFAS exposure and endometrial cancer risk. The results revealed a significant impact of sociodemographic factors on both PFAS levels and endometrial cancer risk. Stress emerged as a notable contributing factor influencing PFAS exposure and the development of endometrial cancer, further emphasizing the importance of stress management practices for overall well-being. By synthesizing evidence from diverse fields, this review underscores the need for interdisciplinary research and targeted interventions to comprehensively address the complex relationship between PFAS, sociodemographic factors, stressors, and endometrial cancer.

Early-life exposure to perfluoroalkyl substances and serum antibody concentrations towards common childhood vaccines in 18-month-old children in the Odense Child Cohort

Exposure to per- and polyfluoroalkyl substances (PFAS) has been associated with reduced antibody response to childhood vaccinations. Previous studies have mostly focused on antibodies against diphtheria or tetanus, while fewer studies have assessed antibodies toward attenuated viruses, such as measles, mumps or rubella (MMR). Therefore, we set out to determine associations between prenatal and early postnatal PFAS exposure and vaccine-specific Immunoglobulin G (IgG) in the background-exposed Odense Child Cohort. Blood samples were drawn in pregnancy at gestation weeks 8-16 and from the offspring at age 18 months. In the maternal serum samples we quantified perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA). In the offspring serum samples we quantified the same five PFAS compounds and IgG towards diphtheria, tetanus and MMR. A total of 880 and 841 children were included in the analyses of diphtheria and tetanus or MMR, respectively. Multiple linear regression models were used for estimation of difference in virus-specific IgG per doubling of PFAS concentrations. Maternal PFAS concentrations were non-significantly inversely associated with most vaccine-specific antibody concentrations. Likewise, child PFAS concentrations were associated with non-significant reductions of antibodies towards tetanus and MMR. A significant reduction in the percent difference in mumps antibody concentration per doubling of child PFNA (-9.2% (95% confidence interval: -17.4;-0.2)), PFHxS (-8.3% (-15.0;-1.0) and PFOS (-7.9% (-14.8;-0.4) was found. These findings are of public health concern, as inadequate response towards childhood vaccines may represent a more general immune dysfunction.

Association between prenatal exposure to per- and polyfluoroalkyl substances and neurodevelopment in children: Evidence based on birth cohort

BACKGROUND

Although numerous studies have examined the effect of prenatal per- and polyfluoroalkyl substances (PFAS) exposure on neurodevelopment in children, findings have been inconsistent.

OBJECTIVE

To better understand the effects of PFAS exposure during pregnancy on offspring neurodevelopment, we conducted a systematic review of prenatal exposure to different types of PFAS and neurodevelopment in children.

METHODS

A comprehensive search was conducted in the PubMed, Web of Science, and EMBASE electronic databases up to March 2023. Only birth cohort studies that report a specific association between PFAS exposure during pregnancy and neurodevelopment were included in this review.

RESULTS

31 birth cohort studies that met the inclusion criteria were qualitatively integrated. Among these, 14 studies investigated the impact of PFAS exposure during pregnancy on cognition, 13 on neurobehavior, and 4 on both cognition and neurobehavior. Additionally, 4 studies explored the influence of PFAS on children's comprehensive development.

CONCLUSION

Prenatal PFAS exposure was associated with poor neurodevelopment in children, including psychomotor development, externalizing behavior, and comprehensive development. However, conclusive evidence regarding its effects on other neurological outcomes remains limited. In addition, sex-specific effects on social behavior and sleep problems were identified.

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.

Association Between Prenatal and Early Postnatal Exposure to Perfluoroalkyl Substances and IQ Score in 7-Year-Old Children From the Odense Child Cohort

Perfluoroalkyl substances (PFAS) are persistent chemicals capable of crossing the placenta and passing into breast milk. Evidence suggests that PFAS exposure may affect brain development. We investigated whether prenatal or early postnatal PFAS exposure was associated with intelligence quotient (IQ) scores in schoolchildren from the Odense Child Cohort (Denmark, 2010-2020). We assessed concentrations of perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA) in maternal serum collected during the first trimester of pregnancy and in child serum at age 18 months. At 7 years of age, children completed an abbreviated version of the Wechsler Intelligence Scale for Children, Fifth Edition, from which Full Scale Intelligence Quotient (FSIQ) and Verbal Comprehension Index scores were estimated. In multiple linear regression analyses conducted among 967 mother-child pairs, a doubling in maternal PFOS and PFNA concentrations was associated with a lower FSIQ score, while no significant associations were observed for PFOA, PFHxS, or PFDA. PFAS concentrations at age 18 months and duration of breastfeeding were strongly correlated, and even in structural equation models it was not possible to differentiate between the opposite effects of PFAS exposure and duration of breastfeeding on FSIQ. PFAS exposure is ubiquitous; therefore, an association with even a small reduction in IQ is of public health concern.

Research Progress on Neurodevelopmental Toxicity in Offspring after Indirect Exposure to PFASs in Early Life

Per- and polyfluoroalkyl substances (PFASs) are widespread environmental pollutants. There is increasing evidence that PFASs have various adverse health effects, including renal toxicity, metabolic dysfunction, endocrine disruption, and developmental toxicity. PFASs have been found to accumulate in the placenta, and some PFASs can cross the placental barrier and subsequently accumulate in the fetus via the maternal-fetal circulation. An increasing number of studies have shown that early life exposure to PFASs can affect fetal neurodevelopment. This paper reviews the characteristics of indirect exposure to PFASs in early life, the effects on neurodevelopment in offspring, and the possible mechanisms of toxic effects.

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.

Association between prenatal or early postnatal exposure to perfluoroalkyl substances and language development in 18 to 36-month-old children from the Odense Child Cohort

BACKGROUND

Perfluoroalkyl substances (PFAS) are persistent chemicals used in everyday consumer products leading to ubiquitous human exposure. Findings of impaired neurodevelopment after prenatal exposure to PFAS are contradictory and few studies have assessed the impact of postnatal PFAS exposure. Language development is a good early marker of neurodevelopment but only few studies have investigated this outcome separately. We therefore investigated the association between prenatal and early postnatal PFAS exposure and delayed language development in 18 to 36-month-old Danish children.

METHODS

The Odense Child Cohort is a large prospective cohort. From 2010 to 2012 all newly pregnant women residing in the Municipality of Odense, Denmark was invited to participate. Concentration of perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) were assessed in maternal serum collected in the 1st trimester of pregnancy and in child serum at 18 months. Parents responded to the Danish adaption of the MacArthur-Bates Communicative Development Inventories (MB-CDI) when their child was between 18 and 36 months. Language scores were converted into sex and age specific percentile scores and dichotomized to represent language scores above or below the 15th percentile. We applied Multiple Imputation by Chained Equation and conducted logistic regressions investigating the association between prenatal and early postnatal PFAS exposure and language development adjusting for maternal age, pre-pregnancy BMI, education and respectively fish intake in pregnancy or childhood and duration of breastfeeding in early postnatal PFAS exposure models.

RESULTS

We found no significant associations between neither prenatal nor early postnatal PFAS exposure and language development among 999 mother-child pairs.

CONCLUSION

In this low-exposed cohort the finding of no association between early postnatal PFAS exposure and language development should be interpreted with caution as we were unable to separate the potential adverse effect of PFAS exposure from the well documented positive effect of breastfeeding on neurodevelopment. We, therefore, recommend assessment of child serum PFAS at an older age as development of the brain proceeds through childhood and even a small impact of PFAS on neurodevelopment would be of public health concern at population level due to the ubiquitous human exposure.

Prenatal Exposure to Legacy and Alternative Per- and Polyfluoroalkyl Substances and Neuropsychological Development Trajectories over the First 3 Years of Life

The neurotoxic effects of prenatal exposure to per- and polyfluoroalkyl substances (PFAS) on offspring animals are well-documented. However, epidemiological evidence for legacy PFAS is inconclusive, and for alternative PFAS, it is little known. In this investigation, we selected 718 mother-child pairs from the Chinese Maoming Birth Cohort Study and measured 17 legacy and alternative PFAS in the third-trimester serum. Neuropsychological developments (communication, gross motor function, fine motor function, problem solving ability, and personal-social skills) were assessed at 3, 6, 12, 18, 24, and 36 months using the Ages and Stages Questionnaires 3rd edition. Trajectories of each subscale were classified into persistently low and persistently high groups via group-based trajectory modeling. Logistic regression and grouped weighted quantile sum were fitted to assess the potential effects of individual PFAS and their mixtures, respectively. Higher linear PFHxS levels were associated with elevated odds for the persistently low trajectories of communication (OR = 1.73; 95% CI: 1.12, 2.66) and problem solving ability (OR = 2.11; 95% CI: 1.14, 3.90). Similar findings were observed for linear PFOS, 1m-PFOS, PFDA, PFDoDA, PFUnDA, and legacy PFAS mixture. However, no association was observed for alternative PFAS and their mixture. We provided insights into the longitudinal links between prenatal legacy/alternative PFAS exposure and neuropsychological development trajectories over the first 3 years of life.

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.

Higher free thyroxine associated with PFAS exposure in first trimester. The Odense Child Cohort

BACKGROUND

Perfluoroalkyl substances (PFAS) are endocrine disrupting chemicals with elimination half-lives ranging from four to eight years. Experimental studies found PFAS able to interfere with thyroid hormone-binding proteins. During the first 20 weeks of gestation (GW), the fetus is reliant on placental transfer of maternal thyroid hormones, mainly free thyroxine (FT4). However, previous studies investigating associations between exposure to PFAS and thyroid hormone status mainly focused on blood samples from late pregnancy or umbilical cord with mixed findings.

OBJECTIVES

To investigate associations between serum-PFAS concentrations and thyroid hormone status in early pregnancy as reflected by FT4 and thyroid-stimulating hormone (TSH).

METHODS

In the Odense Child Cohort, a single-center study, we measured maternal pregnancy serum concentrations of five PFAS: perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA); and FT4 and TSH in 1048 pregnant women at median GW 12 (25th, 75th percentile: 10, 15). Multivariate linear regression models were performed to estimate associations between PFAS exposure and thyroid hormone status.

RESULTS

A doubling in PFOS, PFOA, and PFNA concentrations was associated with an increment in FT4 concentration by 1.85% (95% CI: 0.66%, 3.05%), 1.29% (95% CI: 0.21%, 2.39%), and 1.70% (95% CI: 0.48%, 2.94%), respectively, in adjusted analyses. A statistically significant dose-response relationship was observed across exposure quartiles for PFOS, PFOA, and PFNA in the association with FT4. No association was found between concentrations of PFAS and TSH in adjusted analyses.

CONCLUSION

Exposure to PFOS, PFOA, and PFNA was associated with higher FT4 concentrations in women during early pregnancy. The potential clinical implications of these findings remain to be clarified.

Neurotransmission Targets of Per- and Polyfluoroalkyl Substance Neurotoxicity: Mechanisms and Potential Implications for Adverse Neurological Outcomes

Per- and polyfluoroalkyl substances (PFAS) are a group of persistent environmental pollutants that are ubiquitously found in the environment and virtually in all living organisms, including humans. PFAS cross the blood-brain barrier and accumulate in the brain. Thus, PFAS are a likely risk for neurotoxicity. Studies that measured PFAS levels in the brains of humans, polar bears, and rats have demonstrated that some areas of the brain accumulate greater amounts of PFAS. Moreover, in humans, there is evidence that PFAS exposure is associated with attention-deficit/hyperactivity disorder (ADHD) in children and an increased cause of death from Parkinson's disease and Alzheimer's disease in elderly populations. Given possible links to neurological disease, critical analyses of possible mechanisms of neurotoxic action are necessary to advance the field. This paper critically reviews studies that investigated potential mechanistic causes for neurotoxicity including (1) a change in neurotransmitter levels, (2) dysfunction of synaptic calcium homeostasis, and (3) alteration of synaptic and neuronal protein expression and function. We found growing evidence that PFAS exposure causes neurotoxicity through the disruption of neurotransmission, particularly the dopamine and glutamate systems, which are implicated in age-related psychiatric illnesses and neurodegenerative diseases. Evaluated research has shown there are highly reproduced increased glutamate levels in the hippocampus and catecholamine levels in the hypothalamus and decreased dopamine in the whole brain after PFAS exposure. There are significant gaps in the literature relative to the assessment of the nigrostriatal system (striatum and ventral midbrain) among other regions associated with PFAS-associated neurologic dysfunction observed in humans. In conclusion, evidence suggests that PFAS may be neurotoxic and associated with chronic and age-related psychiatric illnesses and neurodegenerative diseases. Thus, it is imperative that future mechanistic studies assess the impact of PFAS and PFAS mixtures on the mechanism of neurotransmission and the consequential functional effects.