Occurrence, placental transfer, and health risks of emerging endocrine-disrupting chemicals in pregnant women

Typical endocrine disrupting chemicals in newborns with congenital hypothyroidism: Concentrations, exposure assessment, and potential risks

Congenital hypothyroidism (CH) has been reported as a prevalent endocrine disorder in newborns. Endocrine disrupting chemicals (EDCs) have been widely detected in humans and can influence endocrine function, especially thyroid function, and neonates as a susceptible population may be more prone to suffer from CH through exposure to various EDCs. In this study, the concentrations and composition profiles of several typical EDCs were determined in 266 serum samples collected from newborns with (n = 136) and without CH (n = 130) in Beijing, China from 2018 to 2020. All detection rates of target chemicals were higher in newborns with CH than without CH, except for triclosan. Relatively higher levels of phthalate metabolites, parabens, and tetrabromobisphenol A and its alternatives were found in the sera of newborns with CH. Based on the measured concentrations, exposure to and risk of such EDCs were assessed. The median estimated daily intakes of target EDCs ranged from 0.343 (benzophenones) to 161 μg/kg-bw/day (parabens) in the CH group. To explore the possible mechanism of thyroid function damage caused, binary logistic analysis was performed and results revealed that exposure to monocyclohexyl phthalate (mCHP), ethyl-paraben (EtP), bisphenol-Z (BPZ), tetrabromobisphenol A (TBBPA), and 4-hydroxybenzophenone (4-OH-BP) may increase the risk of suffering from CH (adjusted odds ratio (OR): 1.35-1.71). Taken together, this study findings preliminarily uncover the association between exposure to several typical EDCs and the common endocrine disorder CH. Such associations and possible causes should be determined in vitro and in vivo in the follow-up studies.

Comprehensive analysis of transplacental transfer of environmental pollutants detected in paired maternal and cord serums

Prenatal exposure to hazardous environmental pollutants is a critical global concern due to their confirmed presence in umbilical cord blood, indicating the ability of pollutants to cross the placental barrier and expose the fetus to harmful compounds. However, the transplacental transfer efficiencies (TTEs) of many pollutants remain underexplored. Herein, we developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to quantitatively analyze 91 environmental pollutants, including 13 bisphenols (BPs), 18 organophosphorus flame retardants (OPFRs), 7 brominated and other flame retardants (BFRs), 34 phthalates (PAEs), and 19 per- and polyfluoroalkyl substances (PFASs), in paired maternal and cord serums. 38 pollutants were detected in serums, including 5 BPs, 13 OPFRs, 2 BFRs, 4 PAEs, and 14 PFASs. Among the detected pollutants, bisphenol A (BPA) exists in the highest concentration (GM: 10.92 ng/mL in maternal serums and 12.66 ng/mL in cord serums), followed by tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), perfluorooctanoic acid (PFOA), and 4,4'-(1,3-phenylenediisopropylidene) bisphenol (BPM). The exposure concentrations of the same type of pollutants were highly correlated between maternal and cord serums. Perfluorohexanoic acid (PFHxA) had the highest TTE value (5.526), while perfluorooctane sulfonic acid (PFOS) had the lowest (0.206). TTEs of PFOS and perfluorononanoic acid (PFNA) were higher for female newborns, whereas TTEs of perfluorohexadecanoic acid (PFHxDA) and perfluorodecane sulfonic acid (PFDS) were higher for male newborns. Moreover, the expression levels of the transplacental transporters ABCA1, ABCC2, ABCC3, ABCC4, ABCG1, SLCO3A1, and SLC22A3 were associated with the transplacental transfer of triphenyl phosphate (TPHP), TDCIPP, di-n-propyl phthalate (DPRP), perfluoroundecanoic acid (PFUnDA), perfluorotridecanoic acid (PFTrDA), and PFOS. Further research is essential to unveil the mechanisms involved in the transplacental transfer of environmental pollutants, ultimately boosting our comprehension of their impact on fetal health and birth outcomes.

Maternal bisphenol A (BPA) exposure induces placental dysfunction and health risk in adult female offspring: Insights from a mouse model

Bisphenol A (BPA) is an endocrine disruptor that poses multiple risks to human health. In particular, the potential adverse effects of maternal exposure to BPA on offspring warrant further investigation. In this study, pregnant mice were exposed to BPA throughout gestation and the effects of BPA on placental function, fetal development, and health risks in adult offspring were assessed. The results showed that exposure to BPA during pregnancy led to abnormal fetal weight during the mid-to-late stages. Positron emission tomography (PET)/computed tomography (CT) and quantitative polymerase chain reaction (qPCR) were used to assess the expression of glucose transporters. The results showed that maternal BPA exposure altered glucose transport by upregulating Glut1. This alteration may significantly affect placental function and fetal development. Placental metabolomic analysis showed that BPA exposure led to downregulation of key intermediates in glucose metabolism, including UDP-d-glucose and D-glucosamine-6-phosphate. Additionally, the glycerophospholipid metabolite Dipalmitoylphosphatidylcholine (DPPC) was upregulated while CDP-choline and CDP-ethanolamine were downregulated. These disturbances in placental energy metabolism and alterations in glucose transport may be related to decreased fasting blood glucose levels and abnormal glucose tolerance in female offspring; however, these indices remained unaltered in male offspring. These findings provide preliminary insights into the potential pathological mechanisms underlying placental dysfunction and health risk caused by maternal BPA exposure in adult female offspring.

Triclocarban disrupts the activation and differentiation of human CD8+ T cells by suppressing the vitamin D receptor signaling

Triclocarban (TCC) is a widely applied environmental endocrine-disrupting chemical (EDC). Similar to most of EDCs, TCC potentially damages the immunity of various species. However, whether and how TCC impacts the adaptive immunity in mammals has yet to be determined. Herein, we discovered that TCC disrupts the activation and differentiation of CD8+ T cells in primary human peripheral blood samples, purified CD8+ T cells, and in mice in vivo. Mechanistically, TCC might block the activation of the vitamin D receptor (VDR) and reduce the synthesis of cholesterol, a precursor of vitamin D, resulting in inhibition of VDR signaling due to the suppression of both its ligand and the receptor itself by TCC. Our findings elucidate the hazard and potential mechanisms of TCC in mammalian adaptive immunity and highlighted VDR as a potential therapeutic target for the immunodeficiency caused by TCC.

Butylparaben induces glycolipid metabolic disorders in mice via disruption of gut microbiota and FXR signaling

Butylparaben, a common preservative, is widely used in food, pharmaceuticals and personal care products. Epidemiological studies have revealed the close relationship between butylparaben and diabetes; however the mechanisms of action remain unclear. In this study, we administered butylparaben orally to mice and observed that exposure to butylparaben induced glucose intolerance and hyperlipidemia. RNA sequencing results demonstrated that the enrichment of differentially expressed genes was associated with lipid metabolism, bile acid metabolism, and inflammatory response. Western blot results further validated that butylparaben promoted hepatic lipogenesis, inflammation, gluconeogenesis, and insulin resistance through the inhibition of the farnesoid X receptor (FXR) pathway. The FXR agonists alleviated the butylparaben-induced metabolic disorders. Moreover, 16 S rRNA sequencing showed that butylparaben reduced the abundance of Bacteroidetes, S24-7, Lactobacillus, and Streptococcus, and elevated the Firmicutes/Bacteroidetes ratio. The gut microbiota dysbiosis caused by butylparaben led to decreased bile acids (BAs) production and increased inflammatory response, which further induced hepatic glycolipid metabolic disorders. Our results also demonstrated that probiotics attenuated butylparaben-induced disturbances of the gut microbiota and hepatic metabolism. Taken collectively, the findings reveal that butylparaben induced gut microbiota dysbiosis and decreased BAs production, which further inhibited FXR signaling, ultimately contributing to glycolipid metabolic disorders in the liver.

Micro/Nanoplastic Exposure on Placental Health and Adverse Pregnancy Risks: Novel Assessment System Based upon Targeted Risk Assessment Environmental Chemicals Strategy

Micro/nanoplastics (MNPs), as emerging pollutants, have been detected in both the maternal and fetal sides of the placenta in pregnant women, and their reproductive toxicity has been demonstrated in in vivo and in vitro experimental models. The Targeted Risk Assessment of Environmental Chemicals (TRAEC) strategy has been innovatively devised to facilitate valid risk assessment, encompassing a comprehensive evaluation of reliability, correlation, outcome fitness, and integrity across four dimensions based on the included published evidence and our own findings. This study serves as an application case of TRAEC, with 40 items of research evidence on the toxicity of MNPs to the placenta, which were rigorously screened and incorporated into the final scoring system. The final score for this TRAEC case study is 5.63, suggesting a moderate-to-low risk of reproductive toxicity associated with MNPs in the placenta, which may potentially increase with decreasing particle size. It is essential to emphasize that the findings also report original data from assays indicating that exposure to high-dose groups (100 μg/mL, 200 μg/mL) of 50 nm and 200 nm polystyrene nanoplastics (PS-NPs) induces HTR8/SVneo cell cycle arrest and cell apoptosis, which lead to reproductive toxicity in the placenta by disrupting mitochondrial function. Overall, this study employed the TRAEC strategy to provide comprehensive insight into the potential reproductive health effects of ubiquitous MNPs.

Maternal concentrations of environmental phenols during early pregnancy and behavioral problems in children aged 4 years from the Shanghai Birth Cohort

BACKGROUND

Prenatal exposure to environmental phenols such as bisphenol (BPs), paraben (PBs), benzophenone (BzPs), and triclosan (TCS) is ubiquitous and occurs in mixtures. Although some of them have been suspected to impact child behavioral development, evidence is still insufficient, and their mixed effects remain unclear.

OBJECTIVES

To explore the association of prenatal exposure to multiple phenols with child behavioral problems.

METHOD

In a sample of 600 mother-child pairs from the Shanghai Birth Cohort, we quantified 18 phenols (6 PBs, 7 BPs, 4 BzPs, and TCS) in urine samples collected during early pregnancy. Parent-reported Strengths and Difficulties Questionnaires were utilized to evaluate child behavioral difficulties across four subscales, namely conduct, hyperactivity/inattention, emotion, and peer relationship problems, at 4 years of age. Multivariable linear regression was conducted to estimate the relationships between single phenolic compounds and behavioral problems. Additionally, weighted quantile sum (WQS) regression was employed to examine the overall effects of the phenol mixture. Sex-stratified analyses were also performed.

RESULTS

Our population was extensively exposed to 10 phenols (direction rates >50 %), with low median concentrations (1.00 × 10-3-6.89 ng/mL). Among them, single chemical analyses revealed that 2,4-dihydroxy benzophenone (BP1), TCS, and methyl 4-hydroxybenzoate (MeP) were associated with increased behavior problems, including hyperactivity/inattention (BP1: β = 0.16; 95 % confidence interval [CI]: 0.04, 0.30), emotional problems (BP1: β = 0.11; 95 % CI: 0.02, 0.20; TCS: β = 0.08; 95 % CI: 0.02, 0.14), and peer problems (MeP: β = 0.10; 95 % CI: 0.02, 0.18); however, we did not identify any significant association with conduct problems. Further phenol mixture analyses in the WQS model yielded similar results. Stratification for child sex showed stronger positive associations in boys.

CONCLUSION

Our findings indicated that maternal phenol levels during early pregnancy, specifically BP1, TCS, and MeP, are associated with high behavioral problem scores in 4-year-old children.

Perinatal bisphenol S exposure exacerbates the oxidative burden and apoptosis in neonatal ovaries by suppressing the mTOR/autophagy axis

Bisphenol S (BPS) is an emerging environmental endocrine disruptor capable of crossing the placental barrier, resulting in widespread exposure to pregnant women due to its extensive usage. However, the impact of perinatal maternal exposure to BPS on reproductive health in offspring and the underlying molecular mechanism remain underexplored. In this study, gestational ICR mice were provided with drinking water containing 3.33 mg/L BPS to mimic possible human exposure in some countries. Results demonstrated that BPS accelerated the breakdown of germ-cell cysts and the assembly of primordial follicles in neonates, leading to oocyte over-loss. Furthermore, the expression levels of folliculogenesis-related genes (Kit, Nobox, Gdf9, Sohlh2, Kitl, Bmp15, Lhx8, Figla, and Tgfb1) decreased, thus compromising oocyte quality and disrupting early folliculogenesis dynamics. BPS also disrupted other aspects of offspring reproduction, including advancing puberty onset, disrupting the estrus cycle, and impairing fertility. Further investigation found that BPS exposure inhibited the activities and expression levels of antioxidant-related enzymes in neonatal ovaries, leading to the substantial accumulation of MDA and ROS. The increased oxidative burden exacerbated the intracellular apoptotic signaling, manifested by increased expression levels of pro-apoptotic markers (Bax, Caspase 3, and Caspase 9) and decreased expression levels of anti-apoptotic marker (Bcl2). Concurrently, BPS inhibited autophagy by increasing p-mTOR/mTOR and decreasing p-ULK1/ULK1, subsequently down-regulating autophagy flux-related biomarkers (LC3b/LC3a and Beclin-1) and impeding the degradation of autophagy substrate p62. However, the imbalanced crosstalk between autophagy, apoptosis and oxidative stress homeostasis was restored after rapamycin treatment. Collectively, the findings demonstrated that BPS exposure induced reproductive disorders in offspring by perturbing the mTOR/autophagy axis, and such autophagic dysfunction exacerbated redox imbalance and promoted excessive apoptosis. These results provide novel mechanistic insights into the role of autophagy in mitigating BPS-induced intergenerational reproductive dysfunction.

Parabens as environmental contaminants of aquatic systems affecting water quality and microbial dynamics

Among different pollutants of emerging concern, parabens have gained rising interest due to their widespread detection in water sources worldwide. This occurs because parabens are used in personal care products, pharmaceuticals, and food, in which residues are generated and released into aquatic environments. The regulation of the use of parabens varies across different geographic regions, resulting in diverse concentrations observed globally. Concentrations of parabens exceeding 100 μg/L have been found in wastewater treatment plants and surface waters while drinking water (DW) sources typically exhibit concentrations below 6 μg/L. Despite their low levels, the presence of parabens in DW is a potential exposure route for humans, raising concerns for both human health and environmental microbiota. Although a few studies have reported alterations in the functions and characteristics of microbial communities following exposure to emerging contaminants, the impact of the exposure to parabens by microbial communities, particularly biofilm colonizers, remains largely understudied. This review gathers the most recent information on the occurrence of parabens in water sources, as well as their effects on human health and aquatic organisms. The interactions of parabens with microbial communities are reviewed for the first time, filling the knowledge gaps on the effects of paraben exposure on microbial ecosystems and their impact on disinfection tolerance and antimicrobial resistance, with potential implications for public health.