Relationship between exposure of alkylphenols in serum of pregnant women during early pregnancy and adverse birth outcomes

The resveratrol attenuates reactive oxygen species mediated DNA damage in cardiac malformations caused by 4-tert-octylphenol

4-tert-octylphenol (4-t-OP) is an alkylphenolic environmental endocrine disruptor extensively distributed in the environment, posing potential hazards to living organisms. Research has demonstrated that 4-t-OP induces cardiac injury and abnormalities in embryonic development, which can adversely affect heart development. The excessive production of reactive oxygen species (ROS) triggered by 4-t-OP may result in DNA damage. Hence, we hypothesized that ROS-mediated DNA damage plays a crucial role in abnormal cardiac development in zebrafish embryos exposed to 4-t-OP, while resveratrol (RSV), a common antioxidant found in natural foods, may provide protection. In this study, we exposed zebrafish embryos at 2 h post-fertilization (hpf) to various doses of 4-t-OP in combination with relevant inhibitor/agonist therapies. Using microscopy, we observed morphological alterations in the cardiac structure of zebrafish embryos at 72 hpf. The underlying molecular mechanisms were assessed through immunofluorescence, DCFH-DA probe, MitoSOX™ staining, Quantitative polymerase chain reaction, and other methods. Our findings revealed that 4-t-OP caused dose-dependent cardiac defects in zebrafish embryos. The overexpression of ROS/mitochondrial ROS (mtROS) induced by 4-t-OP was significantly reduced by the addition of RSV or the ROS inhibitor N-acetyl-L-cysteine (NAC). Furthermore, the inclusion of RSV or NAC significantly mitigated cardiac deformities, cardiac apoptosis, and DNA damage. Additionally, the apoptosis inhibitor Ac-DEVD-CHO and the Wnt/β-catenin agonist CHIR99021 decreased 4-t-OP-induced cardiac abnormalities. Moreover, the naturally occurring small molecule chemical RSV provided protection against 4-t-OP-induced heart developmental injury. This study elucidates the molecular mechanisms by which 4-t-OP induces oxidative stress, DNA damage, and cardiac defects in the heart of zebrafish larvae through the ROS/Wnt/β-catenin signaling pathway. These findings present novel molecular targets for the prevention and therapy of congenital heart disease, as well as enhance our understanding of the cardiotoxic effects of 4-t-OP.

The ENDOMIX perspective: how everyday chemical mixtures impact human health and reproduction by targeting the immune system†

Endocrine-disrupting chemicals are natural and synthetic compounds found ubiquitously in the environment that interfere with the hormonal-immune axis, potentially impacting human health and reproduction. Exposure to endocrine-disrupting chemicals has been associated with numerous health risks, such as neurodevelopmental disorders, metabolic syndrome, thyroid dysfunction, infertility, and cancers. Nevertheless, the current approach to establishing causality between these substances and disease outcomes has limitations. Epidemiological and experimental research on endocrine-disrupting chemicals faces challenges in accurately assessing chemical exposure and interpreting non-monotonic dose response curves. In addition, most studies have focused on single chemicals or simple mixtures, overlooking complex real-life exposures and mechanistic insights, in particular regarding endocrine-disrupting chemicals' impact on the immune system. The ENDOMIX project, funded by the EU's Horizon Health Program, addresses these challenges by integrating epidemiological, risk assessment, and immunotoxicology methodologies. This systemic approach comprises the triangulation of human cohort, in vitro, and in vivo data to determine the combined effects of chemical mixtures. The present review presents and discusses current literature regarding human reproduction in the context of immunotolerance and chemical disruption mode of action. It further underscores the ENDOMIX perspective to elucidate the impact of endocrine-disrupting chemicals on immune-reproductive health.

Exposure to alkylphenols during early pregnancy and the risk of gestational diabetes mellitus: Fetal sex-specific effects

Alkylphenols (APs) may cause gestational diabetes mellitus (GDM) in pregnant women by impairing glucose metabolism through endocrine disruption. However, the current literature has limited epidemiological evidence on the association between APs exposure and the risk of GDM, especially the lack of evidence on joint exposure. Thus, we evaluated the effect of exposure to APs during early pregnancy on the risk of GDM. The study involved 2035 pregnant women from Guangxi Zhuang Birth Cohort (GZBC) in China. Poisson regression model, restricted cubic spline (RCS), Bayesian kernel machine regression (BKMR), and quantile g-computation (Qgcomp) were conducted to evaluate the effects of serum APs levels on the risk of GDM in pregnant women. For each Ln-unit increase in the serum nonylphenol (NP) of pregnant women, the adjusted relative risk (RR) for GDM risk was 1.12 (95 % CI: 1.00, 1.24). After sex stratification, the effect was more pronounced among pregnant women carrying female fetuses（RR=1.22; 95 % CI: 1.09, 1.38). The serum 4-t-octylphenol (4-T-OP) of the medium-exposure (adjusted RR = 3.25: 95 % CI: 1.30, 8.12) and high-exposure groups (adjusted RR = 2.90: 95 % CI: 1.15, 7.31) were related to a significantly increased risk of GDM in pregnant women carrying female fetuses only when compared to the low-exposure group. A reverse U-shaped nonlinear association was found between 4-n-octylphenol (4-N-OP) and 4-n-nonylphenol (4-N-NP) concentrations and GDM risk, and it was more susceptible in pregnant women carrying female fetuses. The Qgcomp and BKMR models showed that exposure to APs mixtures was correlated with an elevated risk of GDM in pregnant women carrying female fetuses (adjusted OR = 1.90: 95 % CI: 1.07, 3.38). Exposure to APs during early pregnancy may have potential fetal sex-specific effects on the risk of GDM, with pregnant women carrying female fetuses being more susceptible.

Association of alkylphenols exposure with serum liver function markers in pregnant women in Guangxi, China

The liver toxicity of alkylphenols (APs) has been demonstrated in animal studies. However, relevant epidemiological evidence is still lacking in humans, especially during pregnancy. We obtained the levels of biochemical indicators of liver function in early (<13 weeks, mean gestation=9.80±1.96 weeks) and late (≥32 weeks, mean gestation = 37.23±2.45 weeks) pregnancies from 219 pregnant women in the Guangxi Zhuang birth cohort from 2015-2017. We also examined the serum levels of APs in these pregnant women in early pregnancy. The present study aimed to investigate the correlations between the exposure of pregnant women to APs and their serum liver function indices. The results of the generalized linear model (GLM) in this study revealed that nonylphenol (NP) was positively correlated with total bilirubin (TBIL) (P=0.04) in early pregnancy, and 4-n-nonylphenol (4-N-NP) was negatively correlated with glutamyl transferase (GGT) (P=0.012). In late pregnancy, NP was positively associated with TBIL (P=0.002), and 4-tert-octylphenol (4-T-OP) was positively correlated with alanine aminotransferase (ALT) (P=0.02). Restricted cubic spline (RCS) results revealed doseresponse relationships between NP and TBIL (Poverall=0.011) and between 4-N-NP and GGT (Poverall=0.007) in early pregnancy. In late pregnancy, there were doseresponse relationships between NP and TBIL (Poverall=0.001) and between 4-T-OP and ALT (Poverall=0.033). There was also a doseresponse relationship between NP volume and GGT with an inverted 'U' shape (Poverall=0.041, Pnonlinear=0.012). Bayesian kernel machine regression modeling (BKMR) revealed that TBIL increased significantly (P<0.05) with increasing levels of coexposure to APs in both early and late pregnancy. Overall, exposure to APs during pregnancy affects maternal liver function to varying degrees. The present study provides new epidemiological evidence that exposure to alkylphenols in pregnant women interferes with liver function.

Association between prenatal exposure to alkylphenols and intelligence quotient among preschool children: sex-specific effects

BACKGROUND

While prenatal exposure to alkylphenols (APs) has been demonstrated to be associated with neurodevelopmental impairments in animals, the evidence from epidemiological studies remains limited and inconclusive. This study aimed to explore the link between AP exposure during pregnancy and the intelligence quotient (IQ) of preschool children.

METHODS

A total of 221 mother-child pairs from the Guangxi Zhuang Birth Cohort were recruited. Nonylphenol (NP), 4-tert-octylphenol (4-T-OP), 4-n-nonylphenol (4-N-NP), and 4-n-octylphenol were measured in maternal serum in early pregnancy. Childhood IQ was evaluated by the Fourth Edition of Wechsler Preschool and Primary Scale of the Intelligence at 3 to 6 years of age. The impact of APs on childhood IQ were evaluated by generalized linear models (GLMs), restricted cubic spline (RCS), and Bayesian kernel machine regression (BKMR).

RESULTS

In GLMs, prenatal exposure to NP and the second tertile of 4-T-OP exhibited an inverse association with full-scale IQ (FSIQ) (β = -2.38; 95% CI: -4.59, -0.16) and working memory index (WMI) (β = -5.24; 95% CI: -9.58, -0.89), respectively. Prenatal exposure to the third tertile of 4-N-NP showed a positive association with the fluid reasoning index (β = 4.95; 95% CI: 1.14, 8.77) in total children, as well as in girls when stratified by sex. A U-shaped relationship between maternal 4-T-OP and WMI was noted in total children and girls by RCS (all P nonlinear < 0.05). The combined effect primarily driven by NP, of maternal AP mixtures at concentrations above the 50th percentile exhibited an inverse trend on FSIQ in total children and girls in BKMR.

CONCLUSIONS

Prenatal exposure to various APs affects IQ in preschool children, and there may be nonmonotonic and sex-specific effects. Further investigation across the population is required to elucidate the potential neurotoxic effects of APs.

Exposure Profile and Characteristics of Parabens and Alkylphenols in Plasma among Rural Adults in Central China

Parabens and alkylphenols pose serious hazards to human health, yet there are few studies on their exposure profiles and health risks in rural Chinese populations. In this study, 804 participants were selected from the Henan Rural Cohort in mid-eastern China. The plasma levels of parabens (methylparaben, ethylparaben, propylparaben, butylparaben (BuP)) and alkylphenols (4-tert-butylphenol (4-t-BP), 4-tert-octylphenol (4-t-OP)) were analyzed via liquid chromatography-tandem mass spectrometry. Linear regression models were used to investigate factors that may influence pollutant exposure levels. The correlation between contaminants was assessed using Spearman's correlation. The human contaminant intake was estimated using the estimated daily intake (EDI). The health risk was assessed using the hazard quotient (HQ). The detection frequency of four parabens and two alkylphenols exceeded 75%, with median concentrations of 0.444, 0.067, 0.078, 0.053, 8.810, and 6.401 ng/mL, respectively. Significant correlations were observed between parabens, as well as between 4-t-BP and 4-t-OP. Regarding gender, paraben concentrations were higher in women than in men, except for BuP. The EDI for pollutants except 4-t-OP was lower than their respective tolerable/acceptable daily intake. In total, 85.70% of participants had 4-t-OP HQ > 1. A widespread exposure to parabens and alkylphenols among the rural population was found. The high health risks of alkylphenol exposure indicate that alkylphenols should be used with caution.

The Association between 4-Tertiary-Octylphenol, Apoptotic Microparticles, and Carotid Intima-Media Thickness in a Young Taiwanese Population

As one of the most common alkylphenols, 4-tertiary-octylphenol (4-tOP) is commonly used in many consumer products. Our previous epidemiological study revealed a negative correlation between serum 4-tOP levels and carotid intima-media thickness (CIMT), which serves as a biomarker of arteriosclerosis. We aimed to explore the role of apoptotic microparticles, markers of vascular endothelial cell function, in the 4-tOP and CIMT connection. To investigate this, we enrolled 886 Taiwanese adolescents and young adults (aged 12-30 years) and examined the relationships among serum 4-tOP levels, apoptotic microparticles (CD31+/CD42a-, CD31+/CD42a+), and CIMT. Our results showed negative associations among serum 4-tOP levels, both apoptotic microparticles, and CIMT in multiple linear regression analysis. The odds ratios for CIMT (≥75th percentile) and the natural logarithm of 4-tOP were highest when both CD31+/CD42a- and CD31+/CD42a+ were greater than the 50th percentile. Conversely, the odds ratios were lowest when both CD31+/CD42a- and CD31+/CD42a+ were less than the 50th percentile. In the structural equation model, we demonstrated that serum 4-tOP levels were negatively correlated with CIMT and indirectly and negatively correlated with CIMT through both apoptotic microparticles. In conclusion, our study reported the inverse association between 4-tOP apoptotic microparticles and CIMT in a young Taiwanese population. Further experimental studies are needed to clarify these associations.