The association between prenatal exposure to phthalates and cognition and neurobehavior of children-evidence from birth cohorts

Systemic investigation of di-isobutyl phthalate (DIBP) exposure in the risk of cardiovascular via influencing the gut microbiota arachidonic acid metabolism in obese mice model

Phthalate esters (PE), a significant class of organic compounds used in industry, can contaminate humans and animals by entering water and food chains. Recent studies demonstrate the influence of PE on the development and progression of heart diseases, particularly in obese people. Di-isobutyl phthalate (DIBP) was administered orally to normal and diet-induced obese mice in this research to assess cardiovascular risk. The modifications in the microbial composition and metabolites were examined using RNA sequencing and mass spectrometry analysis. Based on the findings, lean group rodents were less susceptible to DIBP exposure than fat mice because of their cardiovascular systems. Histopathology examinations of mice fed a high-fat diet revealed lesions and plagues that suggested a cardiovascular risk. In the chronic DIBP microbial remodeling metagenomics Faecalibaculum rodentium was the predominant genera in obese mice. According to metabolomics data, arachidonic acid (AA) metabolism changes caused by DIBP were linked to unfavorable cardiovascular events. Our research offers new understandings of the cardiovascular damage caused by DIBP exposure in obese people and raises the possibility that arachidonic acid metabolism could be used as a regulator of the gut microbiota to avert related diseases.

Gender associations between phthalate exposure and biomarkers of oxidative stress: A prospective cohort study

Previous epidemiologic research has shown that phthalate exposure in pregnant women is related to adverse birth outcomes in a sex-specific manner. However, the biological mechanism of phthalate exposure that causes these birth outcomes remains poorly defined. In this research, we investigated the association between phthalate exposure and placental oxidative stress in a large population-based cohort study, aiming to initially explore the relationship between phthalate exposure and gene expression in placental oxidative stress in a sex-specific manner. Quantitative PCR was performed to measure the expression of placental inflammatory mRNAs (HO-1, HIF1α, and GRP78) in 2469 placentae. The multiple linear regression models were used to investigate the associations between mRNA and urinary phthalate monoesters. Phthalate metabolites monomethyl phthalate (MMP) and mono-n-butyl phthalate (MBP) were positively correlated with higher HIF1α expression in placentae of male fetuses (p < .05). Mono-benzyl phthalate (MBzP) increased the expression of HO-1, HIF1α, and GRP78 in placentae of male fetuses, and mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) up-regulated the expression of HIF1α and GRP78. Additionally, mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) was negatively correlated with HO-1, HIF1α, and GRP78 in placentae of female fetuses. Maternal phthalate exposure was associated with oxidative stress variations in placental tissues. The associations were closer in the placentas of male fetuses than in that of female ones. The placenta oxidative stress is worth further investigation as a potential mediator of maternal exposure-induced disease risk in children.

Phthalate Exposure and Neurotoxicity in Children: A Systematic Review and Meta-analysis

Objectives: This systematic review aims to assess the relationship between prenatal and childhood exposure to phthalates and neurodevelopmental outcomes, identifying periods of heightened susceptibility. Data sources considered studies examining repeated phthalate exposure during pregnancy and childhood on neurodevelopment. Methods: Evaluation included bias risk and study quality criteria. Evidence was synthesized by groups of low and high phthalate molecular weight and exposure measured prenatally and postnatally and outcome measured in childhood. Beta coefficients and their standard errors were extracted, leading to meta-analyses of various neurodevelopmental outcomes: cognition, motor skills, language, behavior, and temperament. Results: Eleven pregnancy and birth cohort studies were identified as relevant. For each phthalate group and outcome combination, there was low or very low evidence of an association, except for prenatal and postnatal phthalate exposure and behavioral development and postnatal exposure and cognition. Conclusion: The estimated effects sizes were relatively small and strong evidence for periods of heightened susceptibility could not be elucidated. No distinction between phthalates of low molecular weight and those of high molecular weight with regards to the outcomes was found.

Effect of prenatal exposure to phthalates on birth weight of offspring: A meta-analysis

Prenatal exposure to phthalates is common. However, its effect on birth weight has always been met with conflicting conclusions. To explore the effects of prenatal phthalate exposure on neonatal weight, we searched PubMed, Web of Science (WOS), Cochrane Library, and Embase databases for articles published up to October 24, 2023. Observational studies with 95% confidence intervals (CI) were included. Our findings indicate no significant association between either mixed exposure effects or single phthalate metabolites and offspring birth weight when monitoring maternal urine phthalate metabolites. When stratified by sex, ΣHMWPs and MMP significantly reduced the birth weight of female offspring (ΣHMWPs: Pooled β = -62.08, 95%CI: -123.11 to -1.05, P = 0.046; MMP: Pooled β = -10.77, 95%CI: -18.74 to -2.80, P = 0.008). The results of subgroup analysis showed that ΣPAEs and ΣDEHP significantly decreased birth weight in the specific gravity correction group (ΣPAEs: Pooled estimates = -29.31, 95%CI: -58.52 to -0.10, P = 0.049; ΣDEHP: Pooled estimates = -18.25, 95%CI: -33.03 to -3.47, P = 0.016), and MECPP showed a positive correlation in the creatinine correction group (MECPP: Pooled estimates = 18.45, 95%CI: 0.13 to 36.77, P = 0.048). MEP and MBzP were negatively associated with birth weight in the no adjustment for gestational age group (MEP: Pooled estimates = -7.70, 95%CI: -14.19 to -1.21, P = 0.020; MBzP: Pooled estimates = -9.55, 95%CI: -16.08 to -3.03, P = 0.004). To make the results more convincing, more high-quality studies with large samples are urgently required.

Evaluating Mixtures of Urinary Phthalate Metabolites and Serum Per-/Polyfluoroalkyl Substances in Relation to Adolescent Hair Cortisol: The HOME Study

Results of toxicological studies indicate that phthalates and per-/polyfluoroalkyl substances (PFAS), 2 classes of endocrine-disrupting chemicals, may alter the functioning of the hypothalamic-pituitary-adrenocortical (HPA) axis. We evaluated the associations of urinary phthalate metabolites and serum PFAS during gestation and childhood with adolescent hair cortisol concentrations (pg/mg hair) at age 12 years, an integrative marker of HPA axis activity (n = 205 mother-child pairs; Cincinnati, Ohio; enrolled 2003-2006). We used quantile-based g-computation to estimate associations between mixtures of urinary phthalate metabolites or serum PFAS and hair cortisol. We also examined whether associations of individual phthalate metabolites or PFAS with cortisol varied by the timing of exposure. We found that a 1-quartile increase in all childhood phthalate metabolites was associated with 35% higher adolescent hair cortisol (phthalate mixture ψ = 0.13; 95% confidence interval: 0.03, 0.22); these associations were driven by monoethyl phthalate, monoisobutyl phthalate, and monobenzyl phthalate. We did not find evidence that phthalate metabolites during gestation or serum PFAS mixtures were related to adolescent hair cortisol concentrations. We found suggestive evidence that higher childhood concentrations of individual PFAS were related to higher and lower adolescent hair cortisol concentrations. Our results suggest that phthalate exposure during childhood may contribute to higher levels of chronic HPA axis activity.

The Impact of Chronic Phthalate Exposure on Rodent Anxiety and Cognition

Background

There is a growing importance for environmental contributions to psychiatric disorders and understanding the impact of the exposome (i.e., pollutants and toxins). For example, increased biomonitoring and epidemiological studies suggest that daily phthalate chemical exposure contributes to neurological and behavioral abnormalities; however, these mechanisms remain poorly understood. Therefore, the current study was aimed at examining the effects of chronic phthalate exposure on rodent anxiety behaviors and cognition and the impact on hypothalamic-pituitary-adrenal axis function.

Methods

Adult male mice (C57BL6/J) were administered MEHP via drinking water (1 mg/mL), and anxiety-like behavior and cognition combined with hypothalamic-pituitary-adrenal axis and inflammatory assays were assessed after 3 weeks of MEHP exposure.

Results

MEHP-treated mice exhibited enhanced generalized anxiety-like behaviors, as demonstrated by reduced time spent in the open-arm of the elevated plus maze and center exploration in the open field. Tests of spatial memory and cognition were unchanged. Following MEHP administration, circulating levels of corticosterone and proinflammatory cytokines were significantly increased, while at the tissue level, there were MEHP-dependent reductions in glucocorticoid metabolism genes Hsd11b1 and Hsd11b2.

Conclusions

These data suggest that chronic MEHP exposure leads to enhanced generalized anxiety behaviors independent of rodent measures of cognition and memory, which may be driven by MEHP-dependent effects on hypothalamic-pituitary-adrenal axis and peripheral glucocorticoid metabolism function.

Adopting a child perspective for exposome research on mental health and cognitive development - Conceptualisation and opportunities

Mental disorders among children and adolescents pose a significant global challenge. The exposome framework covering the totality of internal, social and physical exposures over a lifetime provides opportunities to better understand the causes of and processes related to mental health, and cognitive functioning. The paper presents a conceptual framework on exposome, mental health, and cognitive development in children and adolescents, with potential mediating pathways, providing a possibility for interventions along the life course. The paper underscores the significance of adopting a child perspective to the exposome, acknowledging children's specific vulnerability, including differential exposures, susceptibility of effects and capacity to respond; their susceptibility during development and growth, highlighting neurodevelopmental processes from conception to young adulthood that are highly sensitive to external exposures. Further, critical periods when exposures may have significant effects on a child's development and future health are addressed. The paper stresses that children's behaviour, physiology, activity pattern and place for activities make them differently vulnerable to environmental pollutants, and calls for child-specific assessment methods, currently lacking within today's health frameworks. The importance of understanding the interplay between structure and agency is emphasized, where agency is guided by social structures and practices and vice-versa. An intersectional approach that acknowledges the interplay of social and physical exposures as well as a global and rural perspective on exposome is further pointed out. To advance the exposome field, interdisciplinary efforts that involve multiple scientific disciplines are crucial. By adopting a child perspective and incorporating an exposome approach, we can gain a comprehensive understanding of how exposures impact children's mental health and cognitive development leading to better outcomes.

Environmental chemical exposures and mental health outcomes in children: a narrative review of recent literature

Background: Mental health is an important factor for children's overall wellbeing. National health statistics show that millions of children are diagnosed with mental health disorders every year, and evidence from studies on chemical pollutants like lead and bisphenols indicate that environmental exposures are linked to mental health illnesses in youth. However, the relationship between children's mental health and the environment is not well understood. This paper aims to review recent literature on prenatal and/or childhood environmental chemical exposures and mental health problems related to mood, anxiety, and behavior. This work also identifies areas of insufficient data and proposes suggestions to fill the data gaps. Methods: A narrative review was performed by searching Google Scholar and PubMed for literature published in the last 6 years (2017-2022), using search terms related to children, mental health, and environmental chemical exposure. Additional relevant studies were identified by screening the references in these papers. Results: A total of 29 studies are included in this review and results are summarized by chemical category: heavy metals, endocrine-disrupting chemicals, and pesticides. The majority of studies reported positive and significant associations between chemical exposures and child mental health outcomes including internalizing and externalizing behaviors. Conclusion: This review demonstrates that there is a growing body of literature that suggests developmental exposure to some environmental chemicals increases a child's risk of mood, anxiety, and behavior problems. Future research should expand on these findings to understand cumulative impacts, chemical mixtures, neurotoxic mechanisms, sex differences, and windows of vulnerability.

Sex difference of pre- and post-natal exposure to six developmental neurotoxicants on intellectual abilities: a systematic review and meta-analysis of human studies

BACKGROUND

Early life exposure to lead, mercury, polychlorinated biphenyls (PCBs), polybromide diphenyl ethers (PBDEs), organophosphate pesticides (OPPs), and phthalates have been associated with lowered IQ in children. In some studies, these neurotoxicants impact males and females differently. We aimed to examine the sex-specific effects of exposure to developmental neurotoxicants on intelligence (IQ) in a systematic review and meta-analysis.

METHOD

We screened abstracts published in PsychINFO and PubMed before December 31st, 2021, for empirical studies of six neurotoxicants (lead, mercury, PCBs, PBDEs, OPPs, and phthalates) that (1) used an individualized biomarker; (2) measured exposure during the prenatal period or before age six; and (3) provided effect estimates on general, nonverbal, and/or verbal IQ by sex. We assessed each study for risk of bias and evaluated the certainty of the evidence using Navigation Guide. We performed separate random effect meta-analyses by sex and timing of exposure with subgroup analyses by neurotoxicant.

RESULTS

Fifty-one studies were included in the systematic review and 20 in the meta-analysis. Prenatal exposure to developmental neurotoxicants was associated with decreased general and nonverbal IQ in males, especially for lead. No significant effects were found for verbal IQ, or postnatal lead exposure and general IQ. Due to the limited number of studies, we were unable to analyze postnatal effects of any of the other neurotoxicants.

CONCLUSION

During fetal development, males may be more vulnerable than females to general and nonverbal intellectual deficits from neurotoxic exposures, especially from lead. More research is needed to examine the nuanced sex-specific effects found for postnatal exposure to toxic chemicals.

Subchronic exposure to di-(2-ethylhexyl) phthalate (DEHP) elicits blood-brain barrier dysfunction and neuroinflammation in male C57BL/6J mice

BACKGROUND

Exposure to di-(2-ethylhexyl) phthalate (DEHP) can cause neurotoxicity but the mechanism is not clear. Blood brain barrier (BBB) is one of the most important tissues to protect the brain. However, whether DEHP can disrupt the BBB or not remains unclear. The objective of this study is to investigate the potential effects of subchronic DEHP exposure on BBB integrity and discuss the role of BBB in DEHP inducible neurotoxicity with an emphasis on neuroinflammatory responses. Male adult C57BL/6J mice were orally administered with vehicle or 200 or 750 mg/kg/day DEHP for 90 days. Subchronic exposure to high-dose DEHP increased water intake but decreased body weight and brain weight. The concentrations of DEHP metabolites increased in serum from all DEHP-exposed groups while increased in brain only from the high-dose group. DEHP induced neurobehavioural alterations and damaged hippocampal neurons. DEHP increased BBB permeability by Evans blue (EB) extravasation and decreased tight junction proteins (ZO-1, occludin, and claudin-5) while presenting a neuroinflammatory feature characterized by the upregulated inflammatory mediators TNF-α and the NLRP3/caspase-1/IL-1β inflammasome pathway. Our data provide new insights into neurotoxicity caused by subchronic DEHP exposure, which is probably involved in BBB dysfunction and neuroinflammatory responses.

Sex differences in children's cognitive functions and phthalates exposure: a meta-analysis

BACKGROUND

Phthalates exposure might affect children's intelligence development. This study aimed to determine (1) whether sex and age affect cognitive function and (2) whether sex differences in cognitive performance are wider with higher phthalate concentrations.

METHODS

Data were collected from PubMed (1998-2022), PROQUEST (1997-2022), and SpringerLink (1995-2022). The study followed the PRISMA process. The included articles were followed by PECO framework. The GRADE applied to assess the certainty of evidence. Of 2422 articles obtained, nine were selected using inclusion criteria. The random-effects model was used to estimate the pooled effects.

RESULTS

Our meta-regression indicated a significant difference between sex differences with age at phthalate concentration assessment (β = -0.25; 95% CI = -0.47, -0.03) and MEHP concentration (β = -0.20; 95% CI = -0.37, -0.03).

CONCLUSIONS

The limitation of the current article is it only provides information on intelligence level rather than other aspects of cognitive function. Thus, the sequelae of phthalate exposure on attention and executive function are still unclear. Our analysis shows significant difference between sex differences in cognitive function scores associated with age at phthalate concentration assessment. Girls might be more resilient in cognitive function at a younger age or during lower concentrations of phthalates metabolites.

IMPACT

This is the first meta-analysis to evaluate the pooled estimates of sex differences in objective cognitive functions among children with phthalate exposure. The female might be a protective factor when exposed to toxic plasticizers while the concentration is low. This study captures the possible role of sex in cognitive functioning and plasticizer exposure through a meta-analysis of children's sex, cognitive scores, and plasticizer exposure.

Prenatal exposure to common plasticizers: a longitudinal study on phthalates, brain volumetric measures, and IQ in youth

Exposure to phthalates, used as plasticizers and solvents in consumer products, is ubiquitous. Despite growing concerns regarding their neurotoxicity, brain differences associated with gestational exposure to phthalates are understudied. We included 775 mother-child pairs from Generation R, a population-based pediatric neuroimaging study with prenatal recruitment, who had data on maternal gestational phthalate levels and T1-weighted magnetic resonance imaging in children at age 10 years. Maternal urinary concentrations of phthalate metabolites were measured at early, mid-, and late pregnancy. Child IQ was assessed at age 14 years. We investigated the extent to which prenatal exposure to phthalates is associated with brain volumetric measures and whether brain structural measures mediate the association of prenatal phthalate exposure with IQ. We found that higher maternal concentrations of monoethyl phthalate (mEP, averaged across pregnancy) were associated with smaller total gray matter volumes in offspring at age 10 years (β per log10 increase in creatinine adjusted mEP = -10.7, 95%CI: -18.12, -3.28). Total gray matter volumes partially mediated the association between higher maternal mEP and lower child IQ (β for mediated path =-0.31, 95%CI: -0.62, 0.01, p = 0.05, proportion mediated = 18%). An association of higher monoisobutyl phthalate (mIBP) and smaller cerebral white matter volumes was present only in girls, with cerebral white matter volumes mediating the association between higher maternal mIBP and lower IQ in girls. Our findings suggest the global impact of prenatal phthalate exposure on brain volumetric measures that extends into adolescence and underlies less optimal cognitive development.

Cognitive Performance and Exposure to Organophosphate Flame Retardants in Children: Evidence from a Cross-Sectional Analysis of Two European Mother-Child Cohorts

The knowledge of the effects of organophosphate flame retardants on children's neurodevelopment is limited. The purpose of the present research is to evaluate the association between exposure to organophosphate flame retardants and children's neurodevelopment in two European cohorts involved in the Human Biomonitoring Initiative Aligned Studies. The participants were school-aged children belonging to the Odense Child Cohort (Denmark) and the PCB cohort (Slovakia). In each cohort, the children's neurodevelopment was assessed through the Full-Scale Intelligence Quotient score of the Wechsler Intelligence Scale for Children, using two different editions. The children's urine samples, collected at one point in time, were analyzed for several metabolites of organophosphate flame retardants. The association between neurodevelopment and each organophosphate flame retardant metabolite was explored by applying separate multiple linear regressions based on the approach of MM-estimation in each cohort. In the Danish cohort, the mean ± standard deviation for the neurodevelopment score was 98 ± 12; the geometric mean (95% confidence interval (95% CI)) of bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) standardized by creatinine (crt) was 0.52 µg/g crt (95% CI = 0.49; 0.60), while that of diphenyl phosphate (DPHP) standardized by crt was 1.44 µg/g crt (95% CI = 1.31; 1.58). The neurodevelopment score showed a small, negative, statistically imprecise trend with BDCIPP standardized by crt (β = -1.30; 95%CI = -2.72; 0.11; p-value = 0.07) and no clear association with DPHP standardized by crt (β = -0.98; 95%CI = -2.96; 0.99; p-value = 0.33). The neurodevelopment score showed a negative trend with BDCIPP (β = -1.42; 95% CI = -2.70; -0.06; p-value = 0.04) and no clear association with DPHP (β = -1.09; 95% CI = -2.87; 0.68; p-value = 0.23). In the Slovakian cohort, the mean ± standard deviation for the neurodevelopment score was 81 ± 15; the geometric mean of BDCIPP standardized by crt was 0.18 µg/g crt (95% CI = 0.16; 0.20), while that of DPHP standardized by crt was 2.24 µg/g crt (95% CI = 2.00; 3.52). The association of the neurodevelopment score with BDCIPP standardized by crt was -0.49 (95%CI = -1.85; 0.87; p-value = 0.48), and with DPHP standardized by crt it was -0.35 (95%CI = -1.90; 1.20; p-value = 0.66). No clear associations were observed between the neurodevelopment score and BDCIPP/DPHP concentrations that were not standardized by crt. No clear associations were observed with bis(1-chloro-2-propyl) phosphate (BCIPP) in either cohort, due to the low detection frequency of this compound. In conclusion, this study provides only limited evidence of an inverse association between neurodevelopment and exposure to BDCIPP and DPHP. The timing of exposure and effect modification of other organophosphate flame retardant metabolites and other substances should be the subject of further investigations that address this scientific hypothesis.

Early-Life Exposure to a Mixture of Phenols and Phthalates in Relation to Child Social Behavior: Applying an Evidence-Based Prioritization to a Cohort with Improved Exposure Assessment

BACKGROUND

Previous studies aiming at relating exposure to phenols and phthalates with child social behavior characterized exposure using one or a few spot urine samples, resulting in substantial exposure misclassification. Moreover, early infancy exposure was rarely studied.

OBJECTIVES

We aimed to examine the associations of phthalates and phenols with child social behavior in a cohort with improved exposure assessment and to a priori identify the chemicals supported by a higher weight of evidence.

METHODS

Among 406 mother-child pairs from the French Assessment of Air Pollution exposure during Pregnancy and Effect on Health (SEPAGES) cohort, 25 phenols/phthalate metabolites were measured in within-subject pools of repeated urine samples collected at the second and third pregnancy trimesters (∼ 21 samples/trimester) and at 2 months and 1-year of age (∼ 7 samples/period). Social behavior was parent-reported at 3 years of age of the child using the Social Responsiveness Scale (SRS). A structured literature review of the animal and human evidence was performed to prioritize the measured phthalates/phenols based on their likelihood to affect social behavior. Both adjusted linear regression and Bayesian Weighted Quantile Sum (BWQS) regression models were fitted. False discovery rate (FDR) correction was applied only to nonprioritized chemicals.

RESULTS

Prioritized compounds included bisphenol A, bisphenol S, triclosan (TCS), diethyl-hexyl phthalate (Σ DEHP ), mono-ethyl phthalate (MEP), mono-n -butyl phthalate (MnBP), and mono-benzyl phthalate (MBzP). With the exception of bisphenols, which showed a mixed pattern of positive and negative associations in pregnant mothers and neonates, few prenatal associations were observed. Most associations were observed with prioritized chemicals measured in 1-y-old infants: Each doubling in urinary TCS (β = 0.78 ; 95% CI: 0.00, 1.55) and MEP (β = 0.92 ; 95% CI: - 0.11 , 1.96) concentrations were associated with worse total SRS scores, whereas MnBP and Σ DEHP were associated with worse Social Awareness (β = 0.25 ; 95% CI: 0.01, 0.50) and Social Communication (β = 0.43 ; 95% CI: - 0.02 , 0.89) scores, respectively. BWQS also suggested worse total SRS [Beta  1 = 1.38 ; 95% credible interval (CrI): - 0.18 , 2.97], Social Awareness (Beta  1 = 0.37 ; 95% CrI: 0.06, 0.70), and Social Communication (Beta  1 = 0.91 ; 95% CrI: 0.31, 1.53) scores per quartile increase in the mixture of prioritized compounds assessed in 1-y-old infants. The few associations observed with nonprioritized chemicals did not remain after FDR correction, with the exception of benzophenone-3 exposure in 1-y-old infants, which was suggestively associated with worse Social Communication scores (corrected p = 0.07 ).

DISCUSSION

The literature search allowed us to adapt our statistical analysis according to the weight of evidence and create a corpus of experimental and epidemiological knowledge to better interpret our findings. Early infancy appears to be a sensitive exposure window that should be further investigated. https://doi.org/10.1289/EHP11798.

Prenatal exposure to phthalates and gender-specific play behavior at seven years of age in the SELMA study

BACKGROUND

A growing body of evidence shows that prenatal exposure to phthalates affects child development. Since many phthalates have been shown to alter endocrine signaling, they may influence reproductive development, neurodevelopment, and child behavior. Indeed, a few studies reported associations between prenatal phthalate exposure and gender-specific play behavior. However, evidence for this relationship is limited, and previous findings are based on single phthalates, while human exposure entails mixtures of chemicals.

OBJECTIVE

We aimed to investigate the associations between prenatal exposure to single phthalates, as well as a phthalate mixture, and gender-specific play behavior.

METHODS

A total of 715 mother-child pairs from the Swedish Environmental Longitudinal, Mother and Child, Asthma and Allergy (SELMA) study were included. In the median week 10 of pregnancy, phthalate metabolites were measured in urine. Gender-specific play behavior was measured with Preschool Activities Inventory at the age of seven years. Linear and weighted quantile sum regressions were used; data was stratified by sex. Models were adjusted for child and maternal age, maternal education, parental attitudes toward play behavior, and urinary creatinine concentration.

RESULTS

For boys, single compound analyses revealed negative associations of prenatal exposure to di-isononyl phthalate (DINP) concentrations with masculine (β = -1.44; 95% CI = -2.72, -0.16) and composite (β = -1.43; 95% CI = -2.72, -0.13) scores. Suggestive associations were also observed with a mixture approach identifying DINP as the main contributor of the association of decreased masculine play. Among girls, higher urinary concentrations of 2,4-methyl-7-oxyooctyl-oxycarbonyl-cyclohexane carboxylic acid (MOiNCH) was associated with decreased feminine (β = -1.59; 95% CI = -2.62, -0.57) and masculine scores (β = -1.22; 95% CI = -2.14, -0.29), whereas the mixture analyses did not yield conclusive results for girls.

CONCLUSION

Our findings suggest associations of prenatal exposure to DINP with decreased masculine play behavior in boys while the results for girls were not fully conclusive.

Assessing CaMPARI as new approach methodology for evaluating neurotoxicity

Developmental exposure to environmental toxicants has been linked to the onset of neurological disorders and diseases. Despite substantial advances in the field of neurotoxicology, there remain significant knowledge gaps in our understanding of cellular targets and molecular mechanisms that mediate the neurotoxicological endpoints associated with exposure to both legacy contaminants and emerging contaminants of concern. Zebrafish are a powerful neurotoxicological model given their high degree sequence conservation with humans and the similarities they share with mammals in micro- and macro-level brain structures. Many zebrafish studies have effectively utilized behavioral assays to predict the neurotoxic potential of different compounds, but behavioral phenotypes are rarely able to predict the brain structures, cell types, or mechanisms affected by chemical exposures. Calcium-modulated photoactivatable ratiometric integrator (CaMPARI), a recently developed genetically-encoded calcium indicator, undergoes a permanent green to red switch in the presence of elevated intracellular Ca2+ concentrations and 405-nm light, which allows for a "snapshot" of brain activity in freely-swimming larvae. To determine whether behavioral results are predictive of patterns of neuronal activity, we assessed the effects of three common neurotoxicants, ethanol, 2,2',3,5',6-pentachlorobiphenyl (PCB 95), and monoethylhexyl phthalate (MEHP), on both brain activity and behavior by combining the behavioral light/dark assay with CaMPARI imaging. We demonstrate that brain activity profiles and behavioral phenotypes are not always concordant and, therefore, behavior alone is not sufficient to understand how toxicant exposure affects neural development and network dynamics. We conclude that pairing behavioral assays with functional neuroimaging tools such as CaMPARI provides a more comprehensive understanding of the neurotoxic endpoints of compounds while still offering a relatively high throughput approach to toxicity testing.

Endocrine-Disrupting Chemicals and Hippocampal Development: The Role of Estrogen and Androgen Signaling

Hormones are important regulators of key processes during fetal brain development. Thus, the developing brain is vulnerable to the action of chemicals that can interfere with endocrine signals. Epidemiological studies have pointed toward sexually dimorphic associations between neurodevelopmental outcomes, such as cognitive abilities, in children and prenatal exposure to endocrine-disrupting chemicals (EDCs). This points toward disruption of sex steroid signaling in the development of neural structures underlying cognitive functions, such as the hippocampus, an essential mediator of learning and memory processes. Indeed, during development, the hippocampus is subjected to the organizational effects of estrogens and androgens, which influence hippocampal cell proliferation, differentiation, dendritic growth, and synaptogenesis in the hippocampal fields of Cornu Ammonis and the dentate gyrus. These early organizational effects correlate with a sexual dimorphism in spatial cognition and are subject to exogenous chemical perturbations. This review summarizes the current knowledge about the organizational effects of estrogens and androgens on the developing hippocampus and the evidence for hippocampal-dependent learning and memory perturbations induced by developmental exposure to EDCs. We conclude that, while it is clear that sex hormone signaling plays a significant role during hippocampal development, a complete picture at the molecular and cellular levels would be needed to establish causative links between the endocrine modes of action exerted by EDCs and the adverse outcomes these chemicals can induce at the organism level.

Perinatal and postnatal exposure to phthalates and early neurodevelopment at 6 months in healthy infants born at term

Background

Phthalates are non-persistent chemicals largely used as plasticizers and considered ubiquitous pollutants with endocrine disrupting activity. The exposure during sensible temporal windows as pregnancy and early childhood, may influence physiological neurodevelopment.

Aims and Scope

The aim of this study is to analyze the relationship between the urinary levels of phthalate metabolites in newborn and infants and the global development measured by the Griffiths Scales of Children Development (GSCD) at six months.

Methods

Longitudinal cohort study in healthy Italian term newborn and their mothers from birth to the first 6 months of life. Urine samples were collected at respectively 0 (T0), 3 (T3), 6 (T6) months, and around the delivery for mothers. Urine samples were analyzed for a total of 7 major phthalate metabolites of 5 of the most commonly used phthalates. At six months of age a global child development assessment using the third edition of the Griffith Scales of Child Development (GSCD III) was performed in 104 participants.

Results

In a total of 387 urine samples, the seven metabolites analyzed appeared widespread and were detected in most of the urine samples collected at any time of sampling (66-100%). At six months most of the Developmental Quotients (DQs) falls in average range, except for the subscale B, which presents a DQ median score of 87 (85-95). Adjusted linear regressions between DQs and urinary phthalate metabolite concentrations in mothers at T0 and in infants at T0, T3 and T6 identified several negative associations both for infants' and mothers especially for DEHP and MBzP. Moreover, once stratified by children's sex, negative associations were found in boys while positive in girls.

Conclusions

Phthalates exposure is widespread, especially for not regulated compounds. Urinary phthalate metabolites were found to be associated to GSCD III scores, showing inverse association with higher phthalate levels related to lower development scores. Our data suggested differences related to the child's sex.

Cumulative Exposure to Phthalates and Their Alternatives and Associated Female Reproductive Health: Body Burdens, Adverse Outcomes, and Underlying Mechanisms

The global birth rate has recently shown a decreasing trend, and exposure to environmental pollutants has been identified as a potential factor affecting female reproductive health. Phthalates have been widely used as plasticizers in plastic containers, children's toys, and medical devices, and their ubiquitous presence and endocrine-disrupting potential have already raised particular concerns. Phthalate exposure has been linked to various adverse health outcomes, including reproductive diseases. Given that many phthalates are gradually being banned, a growing number of phthalate alternatives are becoming popular, such as di(isononyl) cyclohexane-1,2-dicarboxylate (DINCH), di(2-ethylhexyl) adipate (DEHA), and di(2-ethylhexyl) terephthalate (DEHTP), and they are beginning to have a wide range of environmental effects. Studies have shown that many phthalate alternatives may disrupt female reproductive function by altering the estrous cycle, causing ovarian follicular atresia, and prolonging the gestational cycle, which raises growing concerns about their potential health risks. Herein, we summarize the effects of phthalates and their common alternatives in different female models, the exposure levels that influence the reproductive system, and the effects on female reproductive impairment, adverse pregnancy outcomes, and offspring development. Additionally, we scrutinize the effects of phthalates and their alternatives on hormone signaling, oxidative stress, and intracellular signaling to explore the underlying mechanisms of action on female reproductive health, because these chemicals may affect reproductive tissues directly or indirectly through endocrine disruption. Given the declining global trends of female reproductive capacity and the potential ability of phthalates and their alternatives to negatively impact female reproductive health, a more comprehensive study is needed to understand their effects on the human body and their underlying mechanisms. These findings may have an important role in improving female reproductive health and in turn decreasing the number of complications during pregnancy.

The association of prenatal phthalates, organophosphorous pesticides, and organophosphate esters with early child language ability in Norway

BACKGROUND

Prenatal exposure to phthalates, organophosphate esters, and organophosphorous pesticides have been associated with neurodevelopmental deficits including language ability, however, few studies consider the effect of exposure mixtures and the potential longitudinal detriments over time.

OBJECTIVE

This study examines the influence of prenatal exposure to phthalates, organophosphate esters, and organophosphorous pesticides, on children's language ability from toddlerhood to the preschool period.

METHODS

This study includes 299 mother-child dyads from Norway in the Norwegian Mother, Father and Child Cohort Study (MoBa). Prenatal exposure to chemicals were assessed at 17 weeks' gestation, and child language skills were assessed at 18 months using the Ages and Stages Questionnaire communication subscale and at preschool age using the Child Development Inventory. We ran two structural equation models to examine the simultaneous influences of chemical exposures on parent-reported and teacher-reported child language ability.

RESULTS

Prenatal organophosphorous pesticides were negatively associated with preschool language ability through language ability at 18 months. Additionally, there was a negative association between low molecular weight phthalates and teacher-reported preschool language ability. There was no effect of prenatal organophosphate esters on child language ability at either 18 months or preschool age.

CONCLUSIONS

This study adds to the literature on prenatal exposure to chemicals and neurodevelopment and highlights the importance of developmental pathways in early childhood.

Iodine Deficiency, Maternal Hypothyroxinemia and Endocrine Disrupters Affecting Fetal Brain Development: A Scoping Review

This scoping review critically discusses the publications of the last 30 years on the impact of mild to moderate iodine deficiency and the additional impact of endocrine disrupters during pregnancy on embryonal/fetal brain development. An asymptomatic mild to moderate iodine deficiency and/or isolated maternal hypothyroxinemia might affect the development of the embryonal/fetal brain. There is sufficient evidence underlining the importance of an adequate iodine supply for all women of childbearing age in order to prevent negative mental and social consequences for their children. An additional threat to the thyroid hormone system is the ubiquitous exposure to endocrine disrupters, which might exacerbate the effects of iodine deficiency in pregnant women on the neurocognitive development of their offspring. Ensuring adequate iodine intake is therefore essential not only for healthy fetal and neonatal development in general, but it might also extenuate the effects of endocrine disruptors. Individual iodine supplementation of women of childbearing age living in areas with mild to moderate iodine deficiency is mandatory as long as worldwide universal salt iodization does not guarantee an adequate iodine supply. There is an urgent need for detailed strategies to identify and reduce exposure to endocrine disrupters according to the "precautional principle".

The Impact of Chronic Phthalate Exposure on Rodent Anxiety and Cognition

There is a growing importance for environmental contributions to psychiatric disorders and understanding the impact of the exposome (i.e., pollutants and toxins). Increased biomonitoring and epidemiological studies, for example, suggest that daily phthalate chemical exposure contribute to neurological and behavioral abnormalities, however these mechanisms remain poorly understood. The current study therefore aimed to examine the effects of chronic phthalate exposure on rodent anxiety behaviors, cognition, and the impact on hypothalamic-pituitary- adrenal (HPA)-axis function. Adult male mice (C57BL6/J) were administered mono-2-ethylhexyl phthalate (MEHP) via drinking water (1 mg/ml), and anxiety-like behavior, cognition combined with HPA- axis and inflammatory assays were assessed after 3 weeks of MEHP exposure. MEHP-treated mice exhibited enhanced generalized anxiety-like behaviors, as demonstrated by reduced time spent in the open-arm of the elevated plus maze (EPM) and center exploration in the open field (OF). Tests of spatial, cognition and memory function were unchanged. Following MEHP administration, circulating levels of corticosterone and pro- inflammatory cytokines were significantly increased, while at the tissue level, MEHP-dependent reductions in glucocorticoid metabolism genes 11β-hydroxysteroid dehydrogenase (11β-HSD) 1 and 2. These data suggest that chronic MEHP exposure leads to enhanced generalized-anxiety behaviors independent of rodent measures of cognition and memory, which maybe driven by MEHP-dependent effects on HPA-axis and peripheral glucocorticoid metabolism function.

Butyl benzyl phthalate as a key component of phthalate ester in relation to cognitive impairment in NHANES elderly individuals and experimental mice

Phthalates are a group of neurotoxicants with cognitive-disrupting potentials. Given the structural diversity of phthalates, the corresponding neurotoxicity is dramatically altered. To identify the potential contributions of different phthalates on the process of cognitive impairment, data of 836 elders from the NHANES 2011-2014 cycles were used. Survey-weighted logistic regression and principal component analysis-weighted quantile sum regression (PCA-WQSR) models were applied to estimate the independent and combined associations of 11 urinary phthalate metabolites with cognitive deficit (assessed by 4 tests: Immediate Recall (IR), Delayed Recall (DR), Animal Fluency (AF), and Digit Symbol Substitution Test (DSST)) and to identify the potential phthalate with high weight. Laboratory mice were further used to examine the effect of phthalates on cognitive function and to explore the potential mechanisms. In logistic regression models, MBzP was the only metabolite positively correlated with four tests, with ORs of 2.53 (quartile 3 (Q3)), 2.26 (Q3), 2.89 (Q4) and 2.45 (Q2), 2.82 (Q4) for IR, DR, AF, and DSST respectively. In PCA-WQSR co-exposure models, low-molecular-weight (LMW) phthalates were the only PC positively linked to DSST deficit (OR: 1.93), which was further validated in WQSR analysis (WQS OR7-phthalates: 1.56 and WQS OR8-phthalates: 1.55); consistent with the results of logistic regression, MBzP was the dominant phthalate. In mice, butyl benzyl phthalate (BBP), the parent phthalate of MBzP, dose-dependently reduced cognitive function and disrupted hippocampal neurons. Additionally, the hippocampal transcriptome analysis identified 431 differential expression genes, among which most were involved in inhibiting the neuroactive ligand-receptor interaction pathway and activating the cytokine-cytokine receptor interaction pathway. Our study indicates the critical role of BBP in the association of phthalates and cognitive deficits among elderly individuals, which might be speculated that BBP could disrupt hippocampal neurons, activate neuroinflammation, and inhibit neuroactive receptors. Our findings provide new insight into the cognitive-disrupting potential of BBP.

Gestational Exposure to Phthalates and Phthalate Replacements in Relation to Neurodevelopmental Delays in Early Childhood

Phthalates have been linked to changes in child neurodevelopment. However, sex-specificity has been reported inconsistently, and little is known about the impact of recent phthalate replacement chemicals. Our analysis included mother−child pairs (N = 274) from the PROTECT birth cohort in Puerto Rico. Phthalate metabolites were measured in multiple maternal urine collected during pregnancy. Neurodevelopment was measured at 6, 12, and 24 months of age using the Battelle Developmental Inventory-2nd edition (BDI), which provides scores for adaptive, personal-social, communication, motor, and cognitive domains. Multivariable linear regression was used to examine associations between phthalate metabolite concentrations and BDI scores, adjusting for maternal age, maternal education, child age, and specific gravity. Sex-specificity was assessed with sex X exposure interaction terms and stratified models. Results show that all five domains were significantly associated with mono-3-carboxypropyl phthalate (MCPP) at age 24 months, suggesting a holistic developmental delay related to this metabolite. Sex-specificity existed for all timepoints (p-interaction < 0.2), in general, showing stronger associations among boys. For example, metabolites of a recent phthalate replacement, di-2-ethylhexyl terephthalate (DEHTP), were differentially associated with the adaptive domain (boys −7.53%/IQR, 95% CI: −14.58, −0.48 vs. girls −0.85%/IQR, 95% CI: −5.08, 3.37), and the cognitive domain (boys −6.05%/IQR, 95% CI: −10.88, −1.22 vs. girls −1.93%/IQR, 95%CI: −4.14, 0.28) at 6 months. To conclude, gestational exposure to phthalates and phthalate replacements was associated with neurodevelopmental delay across multiple domains, with differences by sex and child age.

Integrated toxicity assessment of DEHP and DBP toward aquatic ecosystem based on multiple trophic model assays

To comprehensively understand the toxic risks of phthalates to aquatic ecosystems, we examined the acute toxicity of di-(2-ethylhexyl) phthalate (DEHP) and di-butyl phthalate (DBP) on multiple trophic models, including algae (Chlorella vulgaris), Daphnia magna and fish (Danio rerio, Pseudorasbora parva). Thus, a 15-day zebrafish exposure was conducted to trace the dynamic changes of phthalate-induced toxic effects. Among the four species, D. magna exhibited the strongest sensitivity to both DEHP and DBP, followed by D. rerio and P. parva. C. vulgaris exhibited the lowest sensitivity to phthalates. The sub-chronic zebrafish assay demonstrated that 1000 μg/L DBP induced significant mortality at 15 days post-exposure (dpe), and DEHP exhibited no lethality at the tested concentrations (10-5000 μg/L). Zebrafish hepatic SOD activity and sod transcription levels were inhibited by DBP from 3 dpe, which was accompanied by increased malondialdehyde level, while zebrafish exposed to DEHP exhibited less oxidative damage. Both DEHP and DBP induced time-dependent alterations on Ache activity in zebrafish brains, thus indicating the potential neurotoxicity toward aquatic organisms. Additionally, 1000 μg/L and higher concentration of DBP caused hepatic DNA damage in zebrafish from 7 dpe. These results provide a better understanding of the health risks of phthalate to water environment.

Exploring associations between urine levels of phthalates and autism spectrum disorder symptoms: a case-control study in Tianjin, China

Autism spectrum disorder (ASD) comprises a group of neurodevelopmental disorders. The etiology of autism remains unclear, but a growing body of evidence indicates that phthalates play a role in its pathogenesis. The aim of this study was to compare the urine levels of phthalates in children with ASD and healthy children. We also explored whether phthalates have an effect on ASD symptoms. The participants in this study included 101 children with ASD (79 boys and 22 girls) and 101 sex- and age-matched controls. The levels of phthalates were analyzed by gas chromatography-mass spectrometry (GC-MS). We detected significant differences in monoethyl phthalate (MEP) levels between the severe ASD and control groups (p < 0.05). Mono-n-butyl phthalate (MBP) concentration was positively correlated with language skill impairment in ASD (β: 0.387, p = 0.041). MEP levels were associated with the CARS "Imitation" score in all children (OR: 1.470). MBP levels were associated with the "Nonverbal Communication" score among boys (OR: 1.233), and MEP levels were associated with the "Nonverbal Communication" score among girls (OR: 2.648). MEP levels were related to the CARS total score after adjustment for sex (β: 1.524, p = 0.047). Compared with the reference mono(2-ethylhexyl) phthalate (MEHP) group, children with ASD in the medium-exposure group had an OR of 3.370 for aggravating ASD severity. These results suggested that increased exposure to phthalates contributes to more ASD symptoms and that there are potentially sex-specific associations. These findings warrant further confirmation.

Concurrent Assessment of Phthalates/HEXAMOLL® DINCH Exposure and Wechsler Intelligence Scale for Children Performance in Three European Cohorts of the HBM4EU Aligned Studies

Information about the effects of phthalates and non-phthalate substitute cyclohexane-1,2-dicarboxylic acid diisononyl ester (HEXAMOLL^® DINCH) on children's neurodevelopment is limited. The aim of the present research is to evaluate the association between phthalate/HEXAMOLL^® DINCH exposure and child neurodevelopment in three European cohorts involved in HBM4EU Aligned Studies. Participating subjects were school-aged children belonging to the Northern Adriatic cohort II (NAC-II), Italy, Odense Child Cohort (OCC), Denmark, and PCB cohort, Slovakia. In each cohort, children's neurodevelopment was assessed through the Full-Scale Intelligence Quotient score (FSIQ) of the Wechsler Intelligence Scale of Children test using three different editions. The children's urine samples, collected for one point in time concurrently with the neurodevelopmental evaluation, were analyzed for several phthalates/HEXAMOLL^® DINCH biomarkers. The relation between phthalates/HEXAMOLL^® DINCH and FSIQ was explored by applying separate multiple linear regressions in each cohort. The means and standard deviations of FSIQ were 109 ± 11 (NAC-II), 98 ± 12 (OCC), and 81 ± 15 (PCB cohort). In NAC-II, direct associations between FSIQ and DEHP's biomarkers were found: 5OH-MEHP+5oxo-MEHP (β = 2.56; 95% CI 0.58-4.55; N = 270), 5OH-MEHP+5cx-MEPP (β = 2.48; 95% CI 0.47-4.49; N = 270) and 5OH-MEHP (β = 2.58; 95% CI 0.65-4.51; N = 270). On the contrary, in the OCC the relation between DEHP's biomarkers and FSIQ tended to be inverse but imprecise (p-value ≥ 0.10). No associations were found in the PCB cohort. FSIQ was not associated with HEXAMOLL^® DINCH in any cohort. In conclusion, these results do not provide evidence of an association between concurrent phthalate/DINCHHEXAMOLLR DINCH exposure and IQ in children.

National-scale urinary phthalate metabolites in the general urban residents involving 26 provincial capital cities in China and the influencing factors as well as non-carcinogenic risks

Phthalates (PAEs) are widely used in daily products but can cause a variety of adverse effects in humans. Few studies have been carried out on human internal exposure levels of PAEs on a large-scale, especially in developing countries. In the present study, 1161 urine samples collected from residents of 26 provincial capitals in China were analyzed for nine phthalate metabolites (mPAEs). The chemicals were widely detected, and the median specific gravity adjusted urinary concentration of Σ₉mPAEs was 278 μg/L. Di-(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DnBP) were the main parent PAEs that the residents were exposed to. Demographic characteristics, such as age and educational level, were significantly associated with PAE exposure. Children and the elderly had higher mPAE levels. Subjects with lower educational levels were more frequently exposed to DnBP and DEHP. However, mono-ethyl phthalate showed the opposite trend, i.e., higher concentrations in subjects aged 18-59 years and with higher educational levels. Geographic differences were detected at the national scale. Residents in northeastern and western China had higher levels of mPAEs than those in central China, most likely because of different industrial usage of the chemicals and different living habits and living conditions of the residents. Health risk assessment showed that hazard indices of PAEs ranged from 0.07 to 9.34, with 20.0% of the subjects being concern for potential non-carcinogenic risk as assessed by Monte Carlo simulation. DEHP and DnBP were the primary contributors, representing 96.7% of total risk. This first large-scale study on PAE human internal exposure in China provides useful information on residents' health in a developing country, which could be used for chemical management and health protection.

Impact of Environmental Pollutants on Gut Microbiome and Mental Health via the Gut–Brain Axis

Over the last few years, the microbiome has emerged as a high-priority research area to discover missing links between brain health and gut dysbiosis. Emerging evidence suggests that the commensal gut microbiome is an important regulator of the gut–brain axis and plays a critical role in brain physiology. Engaging microbiome-generated metabolites such as short-chain fatty acids, the immune system, the enteric nervous system, the endocrine system (including the HPA axis), tryptophan metabolism or the vagus nerve plays a crucial role in communication between the gut microbes and the brain. Humans are exposed to a wide range of pollutants in everyday life that impact our intestinal microbiota and manipulate the bidirectional communication between the gut and the brain, resulting in predisposition to psychiatric or neurological disorders. However, the interaction between xenobiotics, microbiota and neurotoxicity has yet to be completely investigated. Although research into the precise processes of the microbiota–gut–brain axis is growing rapidly, comprehending the implications of environmental contaminants remains challenging. In these milieus, we herein discuss how various environmental pollutants such as phthalates, heavy metals, Bisphenol A and particulate matter may alter the intricate microbiota–gut–brain axis thereby impacting our neurological and overall mental health.

Effects of di-(2-ethylhexyl) phthalate (DEHP) on behavior and dopamine signaling in zebrafish (Danio rerio)

Di (2-ethylhexyl) phthalate (DEHP) is a widely used plasticizer, also known as a developmental toxicant, but its neurobehavioral toxicity remains elusive. This study evaluated the neurobehavioral toxicity and its possible mechanism in larval zebrafish. Embryos at gastrula period (~6 h post fertilization, hpf) were exposure to DEHP (0, 1, 2.5, 5 and 10 mg/L) for 7 days. Spontaneous tail movement in embryos and swimming activity in larvae were monitored. Alterations in the mRNA expression of genes involved in dopamine signaling and apoptosis pathway were assessed. In situ apoptotic cells were assessed by Acridine orange staining, and oxidative damage were measured using enzymatic assay. The behavior results showed that DEHP inhibited spontaneous tail movement and decreased locomotor activities in the light/dark behavioral test. Meanwhile, behavioral changes were accompanied by increased apoptosis and malondialdehyde (MDA) content, decreased superoxide dismutase (SOD) activity and dopamine (DA) content, and perturbed the expression of genes associated with the synthesis (th), reuptake (dat) and metabolism (mao) of DA, with dopamine receptors (DRs), and with the apoptosis pathway (p53, bax, bcl2, caspase-3, caspase-8, caspase-9). The findings will help to illuminate the possible neurobehavioral toxicity mechanisms of organism exposure to DEHP.

Prenatal exposure to phthalates and peripheral blood and buccal epithelial DNA methylation in infants: An epigenome-wide association study

BACKGROUND

Prenatal exposure to phthalates has been associated with adverse health and neurodevelopmental outcomes. DNA methylation (DNAm) alterations may be a mechanism underlying these effects, but prior investigations of prenatal exposure to phthalates and neonatal DNAm profiles are limited to placental tissue and umbilical cord blood.

OBJECTIVE

Conduct an epigenome-wide association study (EWAS) of the associations between prenatal exposure to phthalates and DNAm in two accessible infant tissues, venous buffy coat blood and buccal epithelial cells (BECs).

METHODS

Participants included 152 maternal-infant pairs from the Alberta Pregnancy Outcomes and Nutrition (APrON) study. Maternal second trimester urine samples were analyzed for nine phthalate metabolites. Blood (n = 74) or BECs (n = 78) were collected from 3-month-old infants and profiled for DNAm using the Infinium HumanMethylation450 (450K) BeadChip. Robust linear regressions were used to investigate the associations between high (HMWPs) and low molecular weight phthalates (LMWPs) and change in methylation levels at variable Cytosine-phosphate-Guanine (CpG) sites in infant tissues, as well as the sensitivity of associations to potential confounders.

RESULTS

One candidate CpG in gene RNF39 reported by a previous study examining prenatal exposure to phthalates and cord blood DNAm was replicated. The EWAS identified 12 high-confidence CpGs in blood and another 12 in BECs associated with HMWPs and/or LMWPs. Prenatal exposure to bisphenol A (BPA) associated with two of the CpGs associated with HMWPs in BECs.

DISCUSSION

Prenatal exposure to phthalates was associated with DNAm variation at CpGs annotated to genes associated with endocrine hormone activity (i.e., SLCO4A1, TPO), immune pathways and DNA damage (i.e., RASGEF1B, KAZN, HLA-A, MYO18A, DIP2C, C1or109), and neurodevelopment (i.e., AMPH, NOTCH3, DNAJC5). Future studies that characterize the stability of these associations in larger samples, multiple cohorts, across tissues, and investigate the potential associations between these biomarkers and relevant health and neurodevelopmental outcomes are needed.

A Pathway-Based Genetic Score for Oxidative Stress: An Indicator of Host Vulnerability to Phthalate-Associated Adverse Neurodevelopment

The developing brain is highly sensitive to environmental disturbances, and adverse exposures can act through oxidative stress. Given that oxidative stress susceptibility is determined partly by genetics, multiple studies have employed genetic scores to explore the role of oxidative stress in human disease. However, traditional approaches to genetic score construction face a range of challenges, including a lack of interpretability, bias towards the disease outcome, and often overfitting to the study they were derived on. Here, we develop an alternative strategy by first generating a genetic pathway function score for oxidative stress (gPFSox) based on the transcriptional activity levels of the oxidative stress response pathway in brain and other tissue types. Then, in the Barwon Infant Study (BIS), a population-based birth cohort (n = 1074), we show that a high gPFSox, indicating reduced ability to counter oxidative stress, is linked to higher autism spectrum disorder risk and higher parent-reported autistic traits at age 4 years, with AOR values (per 2 additional pro-oxidant alleles) of 2.10 (95% CI (1.12, 4.11); p = 0.024) and 1.42 (95% CI (1.02, 2.01); p = 0.041), respectively. Past work in BIS has reported higher prenatal phthalate exposure at 36 weeks of gestation associated with offspring autism spectrum disorder. In this study, we examine combined effects and show a consistent pattern of increased neurodevelopmental problems for individuals with both a high gPFSox and high prenatal phthalate exposure across a range of outcomes, including high gPFSox and high DEHP levels against autism spectrum disorder (attributable proportion due to interaction 0.89; 95% CI (0.62, 1.16); p < 0.0001). The results highlight the utility of this novel functional genetic score and add to the growing evidence implicating gestational phthalate exposure in adverse neurodevelopment.

Environmental exposures to pesticides, phthalates, phenols and trace elements are associated with neurodevelopment in the CHARGE study

OBJECTIVE

To determine if higher exposures measured in early childhood to environmental phenols, phthalates, pesticides, and/or trace elements, are associated with increased odds of having a diagnosis of Autism Spectrum Disorder (ASD), Developmental Delay (DD), or Other Early Concerns (OEC) compared to typically developing children (TD).

METHODS

This study included 627 children between the ages of 2-5 who participated in the Childhood Autism Risks from Genetics and Environment (CHARGE) study. Urine samples were collected at the same study visit where diagnostic assessments to confirm diagnosis indicated during the recruitment process were performed. Adjusted multinomial regression models of each chemical with diagnosis as the outcome were conducted. Additionally, two methods were used to analyze mixtures: repeated holdout multinomial weighted quantile sum (WQS) regression for each chemical class; and a total urinary mixture effect was assessed with repeated holdout random subset WQS.

RESULTS

Many urinary chemicals were associated with increased odds of ASD, DD or OEC compared to TD; however, most did not remain significant after false discovery rate adjustment. Repeated holdout WQS indices provided evidence for associations of both a phenol/paraben mixture effect and a trace element mixture effect on DD independently. In analyses adjusted for confounders and other exposures, results suggested an association of a pesticide mixture effect with increased risk for ASD. Results also suggested associations of a total urinary mixture with greater odds of both ASD and DD separately.

CONCLUSION

Higher concentrations of urinary biomarkers were associated with ASD, DD, and OEC compared to TD, with consistency of the results comparing single chemical analyses and mixture analyses. Given that the biospecimens used for chemical analysis were generally collected many months after diagnoses were made, the direction of any causal association is unknown. Hence findings may reflect higher exposures among children with non-typical development than TD children due to differences in behaviors, metabolism, or toxicokinetics.

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.

Human health impacts of exposure to phthalate plasticizers: An overview of reviews

In this review of reviews, we overview the current global body of available evidence from structured reviews of epidemiological studies that explore human health outcomes associated with exposure to phthalates (chemical plasticisers commonly found in plastics). We found robust evidence for an association with lower semen quality, neurodevelopment and risk of childhood asthma, and moderate to robust evidence for impact on anogenital distance in boys. We identified moderate evidence for an association between phthalates/metabolites and low birthweight, endometriosis, decreased testosterone, ADHD, Type 2 diabetes and breast/uterine cancer. There was some evidence for other outcomes including anofourchette distance, fetal sex hormones, pre-term birth, lower antral follicle count, reduced oestrodiol, autism, obesity, thyroid function and hearing disorders. We found no reviews of epidemiological human studies on the impact of phthalates from recycled plastics on human health. We recommend that future research should use urine samples as exposure measures, consider confounders in analyses and measure impacts on female reproductive systems. Our findings align with emerging research indicating that health risks can occur at exposure levels below the "safe dose" levels set out by regulators, and are of particular concern given potential additive or synergistic "cocktail effects" of chemicals. This raises important policy and regulatory issues for identifying and controlling plastics and health related impacts and highlights a need for more research into substances of concern entering plastics waste streams via recycling.

Modification of the association by sex between the prenatal exposure to di(2-ethylhexyl) phthalate and fat percentage in a cohort of Mexicans schoolchildren

INTRODUCTION

Children's overweight and obesity are global public health problems, children with obesity have grater obesity risk as adults, thus leading to develop cardiometabolic diseases. Previous studies have found positive and significant associations between the exposure to phthalates and body mass index and body composition.

OBJECTIVE

To evaluate the modification of the association by sex between DEHP exposure during pregnancy and the percentage of body fat in a cohort of Mexican schoolchildren.

MATERIAL AND METHODS

The sample was comprised by children which had previously participated in a POSGRAD longitudinal study. A subsample of 190 mother-children binomials were included. Mothers' DEHP concentrations and its metabolites had been measured in the second trimester of pregnancy: Mono-2-ethylhexyl phthalate (MEHP), Mono-2-ethyl-5-carboxypentyl phthalate (MECPP), Mono-2-ethyl-5-hidroxyhexyl phthalate (MEHHP), and Mono-2-ethyl-5-oxohexyl phthalate (MEOHP). The children's adipose mass was measured at age 8, 9, and 10. Longitudinal data were analyzed using the mixed effects linear regression model, with intercept and random slope, adjusted by important confounders and stratified by sex.

RESULTS

We found a differentiated effect by sex, the exposure to DEHP during pregnancy significantly increases the adipose mass in boys. The average increase was 0.058% (p = 0.02) for every 1% variation in MECPP; 0.047% (p = 0.04) in MEHHP; 0.051% (p = 0.03) in MEOHP, and 0.066% (p = 0.007) in MECPP.

CONCLUSIONS

The results suggest an effect differentiated by sex; with boys being the main ones affected by the prenatal exposure to phthalates. However, we cannot rule out effects in girls.

Associations of prenatal phthalate exposure with neurobehavioral outcomes in 4.5- and 7.5-month-old infants

Phthalates are ubiquitous endocrine-disrupting chemicals, and research indicates that prenatal exposure to some phthalates may affect neurodevelopment. In a prospective birth cohort study, five first-morning urine samples collected across pregnancy were pooled and the following phthalate biomarkers assessed: sum of di-(2-ethylhexyl) phthalate metabolites (ΣDEHP), sum of diisononyl phthalate metabolites (ΣDINP), sum of dibutyl phthalate metabolites (ΣDBP), sum of anti-androgenic metabolites (ΣAA), monoethyl phthalate (MEP), and sum of all phthalate metabolites (ΣAll). The Ages & Stages Questionnaires® (ASQ), a standardized parent-reported, age-adapted screening tool, measured communication, personal-social, problem solving, and motor domains in infants at 4.5 and 7.5 months (n = 123). Adjusting for maternal age, annual household income, gestational age at birth, infant age at assessment, and sex, repeated-measures generalized linear regression models were used to examine associations between prenatal phthalate urine biomarker concentrations and domain scores (assuming a Poisson distribution). Beta estimates were exponentiated back to the domain scale for ease of interpretation. Mothers were mostly white and college-educated, and most reported an annual household income of ≥$60,000. Associations of phthalate concentrations with ASQ outcomes are presented as follows: (1) anti-androgenic phthalate metabolites (ΣDEHP, ΣDINP, ΣDBP, and ΣAA), (2) MEP, which is not anti-androgenic, and (3) ΣAll. Overall, anti-androgenic phthalates were associated with higher (i.e., better) scores. However, there were exceptions, including the finding that a one-unit increase in ΣDBP was associated with a 12% increase in problem solving scores in 4.5-month-old females (β = 1.12; 95% CI: 0.99, 1.28; p = 0.067) but a 85% decrease for 7.5-month-old females (β = 0.54; 95% CI: 0.3, 0.99; p = 0.047). In contrast, MEP was associated with poorer scores on several outcomes. Sex- and timepoint-specific estimates demonstrated a one-unit increase in MEP was associated with: a 52% decrease in personal-social scores in 7.5-month-old males (β = 0.66; 95% CI: 0.46, 0.95; p = 0.02), a 39% decrease in fine motor scores in 7.5-month-old males (β = 0.72; 95% CI: 0.52, 0.98; p = 0.035), and a 6% decrease in fine motor scores in 4.5-month-old females (β = 0.94; 95% CI: 0.88, 0.99; p = 0.03). A one-unit increase in ΣAll was associated with a 4% increase in personal-social scores in 4.5-month-old males (β = 1.04; 95% CI: 0.99, 1.1; p = 0.08) but a 17% decrease in 7.5-month-old males (β = 0.85; 95% CI: 0.73, 0.99; p = 0.03). These data suggest age- and sex-specific associations of prenatal phthalates with infant neurobehavior. The current findings should be confirmed by longitudinal studies with larger sample sizes.

Review of the Existing Evidence for Sex-Specific Relationships between Prenatal Phthalate Exposure and Children's Neurodevelopment

Phthalates are well-known, ubiquitous environmental contaminants influencing children's health and their neurodevelopment. However, results of the previously conducted studies are not entirely conclusive. The aim of this review is to present the current state of knowledge with respect to the association between the prenatal phthalate exposure and sex-specific child neurodevelopmental outcomes. A systematic search of the literature was carried out to identify the studies that analyse the sex-specific association between prenatal exposure to phthalates and cognitive, psychomotor outcomes and behavioural and emotional problems. The search was conducted in May 2021, and it was limited to the papers published in English between January 2015 and April 2021. The following databases were used: PubMed, Scopus and Elsevier. The selection process was carried out by two independent authors according to the inclusion criteria. Of a total of 7542 records, 17 epidemiological studies met the inclusion criteria with regards to phthalate exposure and sex-specific differences in child neurobehavioural development. The review shows no clear pattern of association between maternal exposure to phthalates during pregnancy and offspring neurodevelopment. No clearly pronounced sex specific effects, except for BBzP exposure and decreased motor ablates among girls, have been indicated. Inconsistences in the results, as well as unsolved issues related to the interpretation of the results in the context of the exposure level, outcomes, confounders, and biological plausibility highlight the necessity for further research in the field.

Innovative methods for remote assessment of neurobehavioral development

In response to the COVID-19 pandemic, research institutions across the globe have modified their operations in ways that have limited or eliminated the amount of permissible in-person research interaction. In order to prevent the loss of important developmentally-timed data during the pandemic, researchers have quickly pivoted and developed innovative methods for remote assessment of research participants. In this manuscript, we describe methods developed for remote assessment of a parent child cohort with a focus on examining the perinatal environment, behavioral and biological indicators of child neurobehavioral development, parent-child interaction, as well as parent and child mental and physical health. We include recommendations relevant to adapting in-laboratory assessments for remote data collection and conclude with a description of the successful dissemination of the methods to eight research sites across the United States, each of whom are involved in Phase 1 of the HEALthy Brain and Child Development (HBCD) Study. These remote methods were born out of pandemic-related necessity; however, they have much wider applicability and may offer advantages over in-laboratory neurodevelopmental assessments.

Systematic Review Methodologies and Endocrine Disrupting Chemicals: Improving Evaluations of the Plastic Monomer Bisphenol A

BACKGROUND

Endocrine disrupting chemicals (EDCs) are found in plastics, personal care products, household items, and other consumer goods. Risk assessments are intended to characterize a chemical's hazards, identify the doses at which adverse outcomes are observed, quantify exposure levels, and then compare these doses to determine the likelihood of risk in a given population. There are many problems with risk assessments for EDCs, allowing people to be exposed to levels that are later associated with serious health outcomes in epidemiology studies.

OBJECTIVE

In this review, we examine issues that affect the evaluation of EDCs in risk assessments (e.g., use of insensitive rodent strains and absence of disease-oriented outcomes in hazard assessments; inadequate exposure assessments). We then review one well-studied chemical, Bisphenol A (BPA; CAS #80-05-7) an EDC found in plastics, food packaging, and other consumer products. More than one hundred epidemiology studies suggest associations between BPA exposures and adverse health outcomes in environmentally exposed human populations.

FINDINGS

We present support for the use of systematic review methodologies in the evaluation of BPA and other EDCs. Systematic reviews would allow studies to be evaluated for their reliability and risk of bias. They would also allow all data to be used in risk assessments, which is a requirement for some regulatory agencies.

CONCLUSION

Systematic review methodologies can be used to improve evaluations of BPA and other EDCs. Their use could help to restore faith in risk assessments and ensure that all data are utilized in decision-making. Regulatory agencies are urged to conduct transparent, well-documented and proper systematic reviews for BPA and other EDCs.

Association between phthalate exposure and insulin resistance: a systematic review and meta-analysis update

An update on systematic review and meta-analysis was performed to explore effects of phthalate exposure on insulin resistance. A systematic literature search was performed in MEDLINE, Web of Science, and CNKI until March 2021. A conceptual framework was constructed to guide the organization and presentation of results. Besides, beta coefficients with corresponding confidence intervals were extracted from the most adjusted models. Extracted beta coefficients were transformed into correlation, and z Fisher transformation of correlation with the corresponding standard error was included in meta-analysis. Subgroup analyses were performed by age (adult vs. adolescent) and sex (female vs. male) of participants and site of study (America and Europe vs. Asia) to explore potential sources of heterogeneity. Nineteen literatures with 12,533 participants reporting on the association of exposure to specific phthalates and insulin resistance were selected. The majority of included studies revealed positive relationships of insulin resistance with different phthalate metabolites exposure. Meta-analyses were performed on 16 studies. Exposure to MnBP, MBzP, MCPP, MEHP, MEOHP, MEHHP, ∑DEHP, and high-molecular weight phthalate (∑HMWP) was associated with the increase of the homeostasis model assessment of insulin resistance (HOMA-IR) index. The results of sensitivity analyses stratified by age, sex, and site of study remained stable, suggesting the robustness of these meta-analyses. Most of heterogeneity in sensitivity analyses decreased to moderate or low degree. Exposure to MnBP, MBzP, MCPP, MEHP, MEOHP, MEHHP, ∑DEHP, and ∑HMWP was associated with the increased risk of HOMA-IR. Age, sex, and site of study might provide limited source of heterogeneity.

Prenatal urinary concentrations of phthalate metabolites and behavioral problems in Mexican children: The Programming Research in Obesity, Growth Environment and Social Stress (PROGRESS) study

BACKGROUND

Phthalate exposure has been associated with increased childhood behavioral problems. Existing studies failed to include phthalate replacements and did not account for high correlations among phthalates. Phthalates' exposure is higher in Mexico than in U.S. locations, making it an ideal target population for this study.

AIM

To examine associations between 15 maternal prenatal phthalate metabolite concentrations and children's behavioral problems.

METHODS

We quantified phthalate metabolites in maternal urine samples from maternal-child dyads (n = 514) enrolled in the Programming Research in Obesity, Growth Environment and Social Stress (PROGRESS) birth cohort in Mexico City. We performed least absolute shrinkage and selection operator (LASSO) regressions to identify associations between specific-gravity adjusted log₂-transformed phthalate metabolites and parent-reported 4-6 year old behavior on the Behavior Assessment System for Children (BASC-2), accounting for metabolite correlations. We adjusted for socio-demographic and birth-related factors, and examined associations stratified by sex.

RESULTS

Higher prenatal mono-2-ethyl-5-carboxypentyl terephthalate (MECPTP) urinary concentrations were associated with increased hyperactivity scores in the overall sample (β = 0.57, 95% CI = 0.17, 1.13) and in girls (β = 0.54, 95% CI = 0.16, 1.08), overall behavioral problems in boys (β = 0.58, 95% CI = 0.20, 1.15), and depression scores in boys (β = 0.44, 95% CI = 0.06, 0.88). Higher prenatal monobenzyl phthalate (MBzP) concentrations were associated with reduced hyperactivity scores in girls (ß = -0.54, 95% CI = -1.08, -0.21).

DISCUSSION

Our findings suggested that prenatal concentrations of phthalates and their replacements altered child neurodevelopment and those associations may be influenced sex.

Endocrine-Disrupting Chemicals and Child Health

While definitions vary, endocrine-disrupting chemicals (EDCs) have two fundamental features: their disruption of hormone function and their contribution to disease and disability. The unique vulnerability of children to low-level EDC exposures has eroded the notion that only the dose makes the thing a poison, requiring a paradigm shift in scientific and policy practice. In this review, we discuss the unique vulnerability of children as early as fetal life and provide an overview of epidemiological studies on programming effects of EDCs on neuronal, metabolic, and immune pathways as well as on endocrine, reproductive, and renal systems. Building on this accumulating evidence, we dispel and address existing myths about the health effects of EDCs with examples from child health research. Finally, we provide a list of effective actions to reduce exposure, and subsequent harm that are applicable to individuals, communities, and policy-makers. Expected final online publication date for the Annual Review of Pharmacology and Toxicology, Volume 62 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Gestational Phthalate Exposure and Preschool Attention Deficit Hyperactivity Disorder in Norway

Supplemental Digital Content is available in the text.

Prenatal phthalate exposure has been linked to altered neurobehavioral development in both animal models and epidemiologic studies, but whether or not these associations translate to increased risk of neurodevelopmental disorders is unclear. We used a nested case-cohort study design to assess whether maternal urinary concentrations of 12 phthalate metabolites at 17 weeks gestation were associated with criteria for Attention Deficit Hyperactivity Disorder (ADHD) classified among 3-year-old children in the Norwegian Mother, Father and Child Cohort Study (MoBa). Between 2007 and 2011, 260 children in this substudy were classified with ADHD using a standardized, on-site clinical assessment; they were compared with 549 population-based controls. We modeled phthalate levels both linearly and by quintiles in logistic regression models adjusted for relevant covariates and tested for interaction by child sex. Children of mothers in the highest quintile of di-iso-nonyl phthalate (∑DiNP) metabolite levels had 1.70 times the odds of being classified with ADHD compared with those in the lowest quintile (95% confidence interval [CI] = 1.03 to 2.82). In linear models, there was a trend with the sum of di-2-ethylhexyl phthalate metabolites (∑DEHP); each natural log-unit increase in concentration was associated with 1.22 times the odds of ADHD (95% CI = 0.99 to 1.52). In boys, but not girls, mono-n-butyl phthalate exposure was associated with increased odds of ADHD (odds ratio [OR] 1.42; 95% CI = 1.07 to 1.88). Additional adjustment for correlated phthalate metabolites attenuated estimates. These results suggest gestational phthalate exposure may impact the behavior of children as young as 3 years.

Associations of gestational phthalate exposure and non-nutritive suck among infants from the Puerto Rico Testsite for Exploring Contamination Threats (PROTECT) birth cohort study

BACKGROUND

Infant non-nutritive suck (NNS), or sucking on a pacifier with no nutrients being delivered, has been used as in index of brain function and has been linked to subsequent neurodevelopment. Yet, no data are available connecting NNS to environmental exposures in utero. The goal of this study was to examine the relationship between gestational exposure to phthalates (a group of chemicals found in personal care products, PVC plastics, and other products) and NNS among infants in a birth cohort study in Puerto Rico.

METHODS

Urinary phthalate metabolite levels were measured in women at up to three time points in pregnancy as a measure of in utero exposure to the child. We calculated the geometric mean of each metabolite for each woman as a measure of exposure across gestation. Infants had their NNS sampled using our custom research pacifier between 4-6 (± 2 weeks) weeks of age, yielding the following NNS dependent measures: cycles/burst, frequency, amplitude, bursts/min, and cycles/min.

RESULTS

Two hundred and eight mother-infant dyads completed this study We used multiple linear regression to assess associations between individual phthalate metabolites and NNS measurements, adjusting for infant sex, birthweight, and urinary specific gravity. An interquartile range (IQR) increase in mono carboxyisononyl phthalate across pregnancy was associated with 3.5% (95%CI: -6.2, -0.8%) lower NNS frequency and 8.9% (0.6, 17.3%) higher NNS amplitude. Similarly, an IQR increase in mono-2-ethylhexyl phthalate was also associated with 3.4% (-6.5, -0.2%) lower NNS frequency, while an IQR increase in di-2-ethylhexyl terephthalate metabolites was associated with 11.2% (2.9, 19.5%) higher NNS amplitude. Gestational exposure to phthalates may alter NNS amplitude and frequency in full-term infants. These findings indicate that the infants may be increasing their NNS amplitude to compensate for their slower NNS frequency. These preliminary findings could have important clinical implications for earlier detection of exposure-related deficits in neurofunction as well as implications for subsequent neurodevelopment and related interventions.

Neurotoxicity of Ortho-Phthalates: Recommendations for Critical Policy Reforms to Protect Brain Development in Children

Robust data from longitudinal birth cohort studies and experimental studies of perinatally exposed animals indicate that exposure to ortho-phthalates can impair brain development and increase risks for learning, attention, and behavioral disorders in childhood. This growing body of evidence, along with known adverse effects on male reproductive tract development, calls for immediate action.Exposures are ubiquitous; the majority of people are exposed to multiple ortho-phthalates simultaneously. We thus recommend that a class approach be used in assessing health impacts as has been done with other chemical classes. We propose critically needed policy reforms to eliminate ortho-phthalates from products that lead to exposure of pregnant women, women of reproductive age, infants, and children. Specific attention should be focused on reducing exposures among socially vulnerable populations such as communities of color, who frequently experience higher exposures.Ortho-phthalates are used in a vast array of products and elimination will thus necessitate a multipronged regulatory approach at federal and state levels. The fact that manufacturers and retailers have already voluntarily removed ortho-phthalates from a wide range of products indicates that this goal is feasible.

A Review of Recent Studies on Bisphenol A and Phthalate Exposures and Child Neurodevelopment

Purpose of Review: Bisphenol A and phthalate have been found in the environment, as well as in humans. In this narrative review pre- and postnatal bisphenol A and phthalate exposures, their relationship to neurodevelopment, and the behavioral outcomes of children are elucidated, focusing in particular on the recent case-control, cross-sectional, and longitudinal studies. This review also introduces some of the possible mechanisms behind the observed associations between exposures and outcomes. Recent Findings: Although bisphenol A and phthalate exposure have been reported to influence neurobehavioral development in children, there are various kinds of test batteries for child neurodevelopmental assessment at different ages whose findings have been inconsistent among studies. In addition, the timing and number of exposure assessments have varied. Summary: Overall, this review suggests that prenatal exposure to bisphenol A and phthalates may contribute to neurobehavioral outcomes in children. The evidence is still limited; however, Attention Deficit Hyperactivity Disorder (ADHD) symptoms, especially among boys, constantly suggested association with both prenatal and concurrent exposure to bisphenol A. Although there is limited evidence on the adverse effects of prenatal and postnatal bisphenol A and phthalate exposures provided, pregnant women and young children should be protected from exposure based on a precautionary approach.

Phthalate mixtures in pregnancy, autistic traits, and adverse childhood behavioral outcomes

BACKGROUND

Prenatal exposure to multiple phthalates is ubiquitous, and yet few studies have evaluated these exposures as a mixture in relation to child autistic traits and behavioral problems.

OBJECTIVES

To assess cumulative associations between prenatal phthalate mixtures and child behaviors, including effect modification by exposure timing and child sex.

METHODS

Analyses included 501 mother/child pairs from the multicenter pregnancy cohort The Infant Development and Environment Study (TIDES). Nine maternal urinary phthalate metabolites were measured in early and late pregnancy, and behavior was assessed at ages 4-5 years using composite T scores for the Behavioral Assessment System for Children (BASC-2), which measures several dimensions of child behavior, and the Social Responsiveness Scale (SRS-2), which measures social impairment consistent with autistic traits. We utilized weighted quantile sum (WQS) regressions to examine pregnancy period-specific associations between phthalate mixtures and behavioral outcomes. Full-sample 95% WQS confidence intervals are known to be anti-conservative, so we calculated a confirmatory p-value using a permutation test. Effect modification by sex was examined with stratified analyses.

RESULTS

A one-quintile increase in the early pregnancy phthalate mixture was associated with increased SRS-2 total score (coefficient = 1.0, confirmatory p = 0.01) and worse adaptive skills (coefficient = -1.0, confirmatory p = 0.06) in both sexes. In sex-stratified analyses, the early pregnancy phthalate mixture was associated with increased SRS-2 total score in boys (coefficient = 1.2, confirmatory p = 0.04) and girls (coefficient = 1.0, confirmatory p = 0.10) and worse BASC-2 adaptive skills score in girls (coefficient = -1.5, confirmatory p = 0.06), while the late pregnancy phthalate mixture was associated with increased BASC-2 externalizing score in boys (coefficient = 1.3, confirmatory p = 0.03).

CONCLUSION

Our results suggest cumulative adverse associations between prenatal phthalate mixtures and multiple facets of childhood behavior.

Gestational Exposure to Phthalates and Social Responsiveness Scores in Children Using Quantile Regression: The EARLI and HOME Studies

Linear regression is often used to estimate associations between chemical exposures and neurodevelopment at the mean of the outcome. However, the potential effect of chemicals may be greater among individuals at the 'tails' of outcome distributions. Here, we investigated distributional effects on the associations between gestational phthalate exposure and child Autism Spectrum Disorder (ASD)-related behaviors using quantile regression. We harmonized data from the Early Autism Risk Longitudinal Investigation (EARLI) (n = 140) Study, an enriched-risk cohort of mothers who had a child with ASD, and the Health Outcomes and Measures of the Environment (HOME) Study (n = 276), a general population cohort. We measured concentrations of 9 phthalate metabolites in urine samples collected twice during pregnancy. Caregivers reported children's ASD-related behaviors using the Social Responsiveness Scale (SRS) at age 3-8 years; higher scores indicate more ASD-related behaviors. In EARLI, associations between phthalate concentrations and SRS scores were predominately inverse or null across SRS score quantiles. In HOME, positive associations of mono-n-butyl phthalate, monobenzyl phthalate, mono-isobutyl phthalate, and di-2-ethylhexyl phthalate concentrations with SRS scores increased in strength from the median to 95th percentile of SRS scores. These results suggest associations between phthalate concentrations and SRS scores may be stronger in individuals with higher SRS scores.