Gestational and peripubertal phthalate exposure in relation to attention performance in childhood and adolescence

TFEB ameliorates DEHP-induced neurotoxicity by activating GAL3/TRIM16 axis dependent lysophagy and alleviating lysosomal dysfunction

Di-(2-ethylhexyl) phthalate (DEHP) is a commonly used plasticizer with known neurotoxic effects. However, the specific mechanism underlying this neurotoxicity remains unclear. This study aimed to investigate the role of lysosomal function and lysophagy in DEHP-induced neurotoxicity, with a particular focus on the regulatory role of Transcription factor EB (TFEB). To achieve this, we utilized in vitro models of DEHP-exposed SH-SY5Y cells and HT22 cells. Our findings revealed that DEHP exposure led to lysosomal damage and dysfunction. Moreover, we observed impaired autophagic degradation, characterized by elevated levels of LC3II and p62. DEHP treatment downregulated the expression of TFEB, GAL3, and TRIM16, while upregulating the expression of PARP. This led to the inhibition of GAL3/TRIM16 axis dependent lysophagy and ultimately excessive apoptosis in neuronal cells. Importantly, TFEB overexpression alleviated lysosomal dysfunction, activated lysophagy, and mitigated DEHP-induced apoptosis. Overall, our results suggest that DEHP induces not only lysosomal dysfunction, but also inhibits lysophagy through the suppression of GAL3/TRIM16 axis. Consequently, impaired clearance of damaged lysosomes occurs, culminating in neuronal apoptosis. Taken together, our findings highlight the critical role of TFEB in regulating lysophagy and lysosomal function. Furthermore, TFEB may serve as a potential therapeutic target for mitigating DEHP-induced neuronal toxicity.

Early childhood exposures to phthalates in association with attention-deficit/hyperactivity disorder behaviors in middle childhood and adolescence in the ReCHARGE study

BACKGROUND

Early-life exposure to phthalates alters behaviors in animals. However, epidemiological evidence on childhood phthalate exposure and attention-deficit/hyperactivity disorder (ADHD) behaviors is limited.

METHODS

This study included 243 children from the ReCHARGE (Revisiting Childhood Autism Risks from Genetics and Environment) study, who were previously classified as having autism spectrum disorder (ASD), developmental delay, other early concerns, and typical development in the CHARGE case-control study. Twenty phthalate metabolites were measured in spot urine samples collected from children aged 2-5 years. Parents reported on children's ADHD symptoms at ages 8-18 years using Conners-3 Parent Rating Scale. Covariate-adjusted negative binomial generalized linear models were used to investigate associations between individual phthalate metabolite concentrations and raw scores. Weighted quantile sum (WQS) regression with repeated holdout validation was used to examine mixture effects of phthalate metabolites on behavioral scores. Effect modification by child sex was evaluated.

RESULTS

Among 12 phthalate metabolites detected in >75% of the samples, higher mono-2-heptyl phthalate (MHPP) was associated with higher scores on Inattentive (β per doubling = 0.05, 95% confidence interval [CI]: 0.02, 0.08) and Hyperactive/Impulsive scales (β = 0.04, 95% CI: 0.00, 0.07), especially among children with ASD. Higher mono-carboxy isooctyl phthalate (MCiOP) was associated with higher Hyperactivity/Impulsivity scores (β = 0.07, 95% CI: -0.01, 0.15), especially among typically developing children. The associations of the molar sum of high molecular weight (HMW) phthalate metabolites and a phthalate metabolite mixture with Hyperactivity/Impulsivity scores were modified by sex, showing more pronounced adverse associations among females.

CONCLUSION

Exposure to phthalates during early childhood may impact ADHD behaviors in middle childhood and adolescence, particularly among females. Although our findings may not be broadly generalizable due to the diverse diagnostic profiles within our study population, our robust findings on sex-specific associations warrant further investigations.

Early childhood exposure to environmental phenols and parabens, phthalates, organophosphate pesticides, and trace elements in association with attention deficit hyperactivity disorder (ADHD) symptoms in the CHARGE study

BACKGROUND

A growing body of literature investigated childhood exposure to environmental chemicals in association with attention-deficit/hyperactivity disorder (ADHD) symptoms, but limited studies considered urinary mixtures of multiple chemical classes. This study examined associations of concurrent exposure to non-persistent chemicals with ADHD symptoms in children diagnosed with autism spectrum disorder (ASD), developmental delay (DD), and typical development (TD).

METHODS

A total of 549 children aged 2-5 years from the Childhood Autism Risks from Genetics and Environment (CHARGE) case-control study were administered the Aberrant Behavior Checklist (ABC). This study focused on the ADHD/noncompliance subscale and its two subdomains (hyperactivity/impulsivity, inattention). Sixty-two chemicals from four classes (phenols/parabens, phthalates, organophosphate pesticides, trace elements) were quantified in child urine samples, and 43 chemicals detected in > 70% samples were used to investigate their associations with ADHD symptoms. Negative binomial regression was used for single-chemical analysis, and weighted quantile sum regression with repeated holdout validation was applied for mixture analysis for each chemical class and all chemicals. The mixture analyses were further stratified by diagnostic group.

RESULTS

A phthalate metabolite mixture was associated with higher ADHD/noncompliance scores (median count ratio [CR] = 1.10; 2.5th, 97.5th percentile: 1.00, 1.21), especially hyperactivity/impulsivity (median CR = 1.09; 2.5th, 97.5th percentile: 1.00, 1.25). The possible contributors to these mixture effects were di-2-ethylhexyl phthalate (DEHP) metabolites and mono-2-heptyl phthalate (MHPP). These associations were likely driven by children with ASD as these were observed among children with ASD, but not among TD or those with DD. Additionally, among children with ASD, a mixture of all chemicals was associated with ADHD/noncompliance and hyperactivity/impulsivity, and possible contributors were 3,4-dihydroxy benzoic acid, DEHP metabolites, MHPP, mono-n-butyl phthalate, and cadmium.

CONCLUSIONS

Early childhood exposure to a phthalate mixture was associated with ADHD symptoms, particularly among children with ASD. While the diverse diagnostic profiles limited generalizability, our findings suggest a potential link between phthalate exposure and the comorbidity of ASD and ADHD.

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.

Early childhood exposure to environmental phenols and parabens, phthalates, organophosphate pesticides, and trace elements in association with attention deficit hyperactivity disorder (ADHD) symptoms in the CHARGE study

Background

Agrowing body of literature investigated childhood exposure to environmental chemicals in association with attention deficit hyperactivity disorder (ADHD) symptoms, but limited studies considered urinary mixtures of multiple chemical classes. This study examined associations of concurrent exposure to non-persistent chemicals with ADHD symptoms in children diagnosed with autism spectrum disorder (ASD), developmental delay, and typical development.

Methods

A total of 574 children aged 2-5 years from the Childhood Autism Risks from Genetics and Environment (CHARGE) case-control study was administered the Aberrant Behavior Checklist (ABC). This study focused on the Hyperactivity subscale and its two subdomains (hyperactivity/impulsivity, inattention). Sixty-two chemicals from four classes (phenols/parabens, phthalates, organophosphate pesticides, trace elements) were quantified in child urine samples, and 43 chemicals detected in >70% samples were used in statistical analyses. Weighted quantile sum regression for negative binomial outcomes with repeated holdout validation was performed to investigate covariate-adjusted associations between mixtures and ABC scores in 574 children. The mixture analyses were further restricted to 232 children with ASD.

Results

Phthalate metabolite mixtures, weighted for mono-n-butylphthalate (MNBP), mono-2-heptyl phthalate, and mono-carboxy isononyl phthalate, were associated with the Hyperactivity subscale (mean incidence rate ratio [mIRR] = 1.11; 2.5th, 97.5th percentile: 1.00, 1.23), especially the hyperactivity/impulsivity subdomain (mIRR = 1.14; 2.5th, 97.5th percentile: 1.06, 1.26). These associations remained similar after restricting to children with ASD. The inattention subdomain was associated with a phenols/parabens mixture, weighted for several parabens and bisphenols (mIRR = 1.13; 2.5th, 97.5th percentile: 1.00, 1.28) and a total mixture, weighted for 3,4-dihydroxy benzoic acid, MNBR and mono-(2-ethyl-5-carboxypentyl) phthalate (mIRR = 1.11; 2.5th, 97.5th percentile: 1.01,1.25) only among children with ASD.

Conclusions

Concurrent exposure to phthalate mixtures was associated with hyperactivity in early childhood. Though causal inference cannot be made based on our cross-sectional findings, this study warrants further research on mixtures of larger number of chemicals from multiple classes in association with ADHD-related behaviors in young children.