Fetal and Infancy Exposure to Phenols, Parabens, and Phthalates and Anthropometric Measurements up to 36 Months, in the Longitudinal SEPAGES Cohort.

BACKGROUND: Endocrine-disrupting chemicals may play a role in adiposity development during childhood. Until now literature in this scope suffers from methodologic limitations in exposure assessment using one or few urine samples and missing assessment during the infancy period. OBJECTIVES: We investigated the associations between early-life exposure to quickly metabolized chemicals and post-natal growth, relying on repeated within-subject urine collections over pregnancy and infancy. METHODS: We studied the associations of four phenols, four parabens, seven phthalates, and one nonphthalate plasticizer from weekly pooled urine samples collected from the mother during second and third trimesters (median 18 and 34 gestational weeks, respectively) and infant at 2 and 12 months of age, and child growth until 36 months. We relied on repeated measures of height, weight and head circumference from study visits and the child health booklet to predict growth outcomes at 3 and 36 months using the Jenss-Bayley nonlinear mixed model. We assessed associations with individual chemicals using adjusted linear regression and mixtures of chemicals using a Bayesian kernel machine regression model. RESULTS: The unipollutant analysis revealed few associations. Bisphenol S (BPS) at second trimester was positively associated with all infant growth parameters at 3 and 36 months, with similar patterns between exposure at third trimester and all infant growth parameters at 3 months. Mono-n-butyl phthalate (MnBP) at 12 months was positively associated with body mass index (BMI), weight, and head circumference at 36 months. Mixture analysis revealed positive associations between exposure at 12 months and BMI and weight at 36 months, with MnBP showing the highest effect size within the mixture. CONCLUSIONS: This study suggests that exposure in early infancy may be associated with increased weight and BMI in early childhood, which are risk factors of obesity in later life. Furthermore, this study highlighted the impact of BPS, a compound replacing bisphenol A, which has never been studied in this context. https://doi.org/10.1289/EHP13644.

A study on assessing the toxic effects of ethyl paraben on rohu (Labeo rohita) using different biomarkers; hemato-biochemical assays, histology, oxidant and antioxidant activity and genotoxicity.

Parabens are being used as preservatives due to their antifungal and antimicrobial effects. They are emerging as aquatic pollutants due to their excessive use in many products. The purpose of this study was to determine the toxic effect of ethyl paraben (C9H10O3) on the hematobiochemical, histological, oxidative, and anti-oxidant enzymatic and non-enzymatic activity; the study also evaluates the potential of ethyl paraben to cause genotoxicity in Rohu Labeo rohita. A number of 15 fish with an average weight of 35.45±1.34g were placed in each group and exposed to ethyl paraben for 21 days. Three different concentrations of ethyl paraben, i.e., T1 (2000µg/L), T2 (4000 µg/L), andT3 (6000 µg/L) on which fish were exposed as compared to the control T0 (0.00 µg/L). Blood was used for hematobiochemical and comet assay. Gills, kidneys, and liver were removed for histological alterations. The results showed a significant rise in all hemato-biochemical parameters such as RBCs, WBCs, PLT count, blood sugar, albumin, globulin, and cholesterol. An increase in aspartate aminotransferase (AST) and alanine transaminase (ALT) levels directed the hepatocytic damage. Histological alterations in the liver, gills and kidneys of fish were found. Ethylparaben induces oxidative stress by suppressing antioxidant enzyme activity such as SOD, GSH, CAT and POD. Based on the comet assay, DNA damage was also observed in blood cells, resulting in genotoxicity. Findings from the present study indicate that ethyl paraben induces hemato-biochemical alterations, tissue damage, oxidative stress, and genotoxicity.

The combined effects of preservative chemicals in consumer products: An analysis using embryonic and adult zebrafish.

Benzisothiazolinone (BIT) and propyl paraben (PP) are preservatives in cleaning products; however, their toxicities are not well understood. In this study, zebrafish embryos were exposed to BIT, PP, and mixtures of both for 96 h to investigate the effects on growth hormone (GH), insulin-like growth factor-1 (IGF-1), and the transcription of 19 genes related to the GH/IGFs axis. Concentrations of BIT and PP were measured in the whole body of larvae. Zebrafish pairs were also exposed to BIT, PP, and mixtures for 21 d to evaluate the effects on sex hormones, histology in gonad, and transcription of 22 genes related to the hypothalamus-pituitary-gonad axis and vitellogenin. The mixtures had potentiation effects on development, reproduction, hormones, and gene transcripts than individual exposure. Larvae exposed to 229 µg L-1 BIT, 64.5 µg L-1 PP, and mixtures showed reduced growth. Decreased GH and IGF-1 levels were supported by gene regulation associated with the GH/IGFs axis. In larvae, reactive oxygen species, superoxide dismutase, catalase, and glutathione peroxidase levels were increased under all exposures. The gonadosomatic index in males and number of eggs decreased after mixture exposure. In females exposed to mixtures, the percentage of atretic follicle in ovary was significantly increased. The significant decrease in testosterone in males and significant decrease in 17ß-estradiol in females exposed to mixtures suggest anti-estrogenic and anti-androgenic potential. Thus, preservative mixtures in consumer products may be more toxic than the individual substances, which is important for managing the risks of mixing preservatives.

Butylparaben induced zebrafish (Danio rerio) kidney injury by down-regulating the PI3K-AKT pathway.

Butylparaben, a common endocrine disruptor in the environment, is known to be toxic to the reproductive system, heart, and intestines, but its nephrotoxicity has rarely been reported. In order to study the nephrotoxicity and mechanism of butylparaben, we examined the acute and chronic effects on human embryonic kidney cells (HEK293T) and zebrafish. Additionally, we assessed the potential remedial effects of salidroside against butylparaben-induced nephrotoxicity. Our in vitro findings demonstrated oxidative stress and cytotoxicity to HEK293T cells caused by butylparaben. In the zebrafish model, the concentration of butylparaben exposure ranged from 0.5 to 15 µM. An assortment of experimental techniques was employed, including the assessment of kidney tissue morphology using Hematoxylin-Eosin staining, kidney function analysis via fluorescent dextran injection, and gene expression studies related to kidney injury, development, and function. Additionally, butylparaben caused lipid peroxidation in the kidney, thereby damaging glomeruli and renal tubules, which resulted from the downregulation of the PI3K-AKT signaling pathway. Furthermore, salidroside ameliorated butylparaben-induced nephrotoxicity through the PI3K-AKT signaling pathway. This study reveals the seldom-reported kidney toxicity of butylparaben and the protective effect of salidroside against toxicological reactions related to nephrotoxicity. It offers valuable insights into the risks to kidney health posed by environmental toxins.

Non-persistent endocrine disrupting chemical mixtures and uterine leiomyomata in the study of environment, lifestyle and fibroids (SELF).

BACKGROUND: Results of studies investigating associations between individual endocrine-disrupting chemicals (EDCs) and incidence of uterine leiomyomata (UL), a hormone-dependent gynecological condition, have been inconsistent. However, few studies have evaluated simultaneous exposure to a mixture of EDCs with UL incidence. METHODS: We conducted a case-cohort analysis (n = 708) of data from the Study of the Environment, Lifestyle and Fibroids (SELF), a prospective cohort study. Participants were aged 23-35 years at enrollment, had an intact uterus, and identified as Black or African American. We measured biomarker concentrations of 21 non-persistent EDCs, including phthalates, phenols, parabens, and triclocarban, in urine collected at baseline, 20-month, and 40-month clinic visits. We ascertained UL incidence and characteristics using ultrasounds at baseline and approximately every 20 months through 60 months. We used probit Bayesian Kernel Machine Regression (BKMR-P) to evaluate joint associations between EDC mixtures with cumulative UL incidence. We estimated the mean difference in the probit of UL incidence over the study period, adjusting for baseline age, education, years since last birth, parity, smoking status and body mass index. We converted probit estimates to odds ratios for ease of interpretation. RESULTS: We observed that urinary concentrations of the overall EDC mixture were inversely associated with UL incidence in the overall mixtures model, with the strongest inverse associations at the 70th percentile of all biomarkers compared with their 50th percentile (odds ratio = 0.59; 95% confidence interval: 0.36, 0.96). Strongest contributors to the joint association for the mixture were bisphenol S (BPS), ethyl paraben (EPB), bisphenol F (BPF) and mono (2-ethyl-5-carboxypentyl) phthalate (MECPP), which each demonstrated inverse associations except for MECPP. There was suggestive evidence of an interaction between MECPP and EPB. CONCLUSION: In this prospective ultrasound study, we observed evidence of an inverse association between the overall mixture of urinary biomarker concentrations of non-persistent EDCs with UL incidence.

Potential molecular mechanism of photosynthesis regulation by PeMPK7 in poplar under para-hydroxybenzoic acid stress.

Due to continuous plantation of poplar, its growth and biomass accumulation may be negatively affected by the accumulation of allelochemicals such as para-hydroxybenzoic acid (pHBA) in soil. As photosynthesis is the most fundamental process in plants, it can be negatively impacted by pHBA stress. Therefore, it is crucial to improve photosynthetic capacity under pHBA stress to facilitate poplar plant growth. The mitogen-activated protein kinase (MAPK) cascade pathway is widely involved in environmental stress responses in plants. However, the regulation mechanisms of photosynthesis-related pathways by MAPK pathway genes under pHBA stress are still unclear. In this study, through transcriptome analysis and weighted gene co-expression network analysis, we observed that PeMPK7 overexpression in poplar can regulate the expression of photosynthesis-related genes and transcription factor genes, namely, WRKY1, WRKY33, and ERF3, during the early stage of pHBA stress. In addition, PeMPK7 can improve photosynthesis in poplar under long-term pHBA stress. Moreover, yeast two-hybrid and pull-down assays confirmed the interaction between PeMPK7 and PeMKK7/10. Based on these results, a schematic diagram of the pathways involved in the regulation of photosynthesis by PeMPK7 was constructed. This study provided novel insights into the molecular mechanisms of regulation of pHBA stress via MAPK cascade pathway.

Influence of microplastic contamination on the dissipation of endocrine disrupting chemicals in soil environment.

Microplastic (MP) contamination is in the spotlight today, yet knowledge of their interaction with other organic contaminants in the soil environment is limited. Concerns extend to endocrine disrupting chemicals (EDCs), known for their potential to interfere with the hormonal systems of organisms and for their persistence and widespread presence in the environment. In this study, the most frequently occurring EDCs were monitored both in alluvial soil and in soil contaminated with different MPs commonly found in soil media, polyethylene, polyamide, and polystyrene. Bisphenol A and parabens were the most rapidly dissipating compounds, followed by triclosan and triclocarban, with the latter showing poor degradation. Per- and polyfluoroalkyl substances (PFAS) showed high persistence as concentrations remained nearly constant throughout the experiment. Although they fitted well with first-order dissipation kinetics, most showed biphasic behavior. The co-occurrence of MPs in the soil influenced the kinetic behavior in most cases although the differences were not very marked. MPs could impact sorption-desorption processes, affecting contaminant mobility and bioavailability to organisms in soil. These findings strengthen evidence for the influence of MPs on the behavior of soil contaminants such as EDCs, not only as vectors or sources of contaminants but by affecting dissipation kinetics.

Target and Suspect Screening for Organic Additives in Six Classifications of Personal Care Products Using Liquid Chromatography-High-Resolution Mass Spectrometry.

Personal care products (PCPs) are integral components of daily human existence, including a large number of chemicals intentionally added for functional attributes (e.g., preservatives and fragrances) or unintentionally present, such as plasticizers. This investigation aimed to optimize the methodology for target and suspect screening via liquid chromatography-high-resolution mass spectrometry, focusing on nine prevalent organic additives (comprising bisphenols A, F, and S, methyl, ethyl, propyl, and butylparaben, 5-chloro-2-methyl-4-isothiazolin-3-one, and 4-hydroxybenzoic acid). A total of 50 high-selling PCPs were purchased from the local online market as samples. In detail, PCP samples were classified into body washes, shampoos, hair conditioners, facial cleansers, body lotions, and moisture creams. For calibration, the quality assurance and quality control results demonstrated a coefficient of determination (R2) surpassing 0.999, with detection and quantification limits ranging from 2.5 to 100.0 ng/g. For recovery experiments, replicate recoveries (n = 5) ranged from 61 to 134%. In purchased PCP samples, five of the nine target compounds were detected via a target screening. Methylparaben exhibited the highest concentration (7860 mg/kg) in a facial cleanser, which is known as an endocrine-disrupting chemical. A total of 248 suspects of organic additives were screened in PCPs, leading to a tentative identification of 9. Confirmation (confidence level 1) via reference standards was achieved for three suspects, while six were tentatively identified with a confidence level of 2. This two-step extraction methodology utilizing methyl tert-butyl ether and isopropyl alcohol enabled simultaneous analysis of diverse chemical groups with distinct properties.

Production of Biomass-Derived p-Hydroxybenzamide: Synthesis of p-Aminophenol and Paracetamol.

As we work to transition the modern society that is based on non-renewable chemical feedstocks to a post-modern society built around renewable sources of energy, fuels, and chemicals, there is a need to identify the renewable resources and processes for converting them to platform chemicals. Herein, we explore a strategy for utilizing the p-hydroxybenzoate in biomass feedstocks (e. g., poplar and palm trees) and converting it into a portfolio of commodity chemicals. The targeted bio-derived product in the first processing stage is p-hydroxybenzamide produced from p-hydroxybenzoate esters found in the plant. In the second stage a continuous reaction process converts the p-hydroxybenzamide to p-aminophenol via the Hofmann rearrangement and recovers the unreacted p-hydroxybenzamide. In the third stage the p-aminophenol can be acetylated to form paracetamol, which is readily isolated by liquid/liquid extraction at >95 % purity and an overall p-hydroxybenzamide-to-paracetamol process yield of ~90 %. We explore how utilization of protecting groups alters the challenges in this process and expands the portfolio of possible products to include p-(methoxymethoxy)aniline and N-acetyl-p-(methoxymethoxy)aniline. These target compounds could become value-added renewably-sourced platform chemicals that could be used to produce biodegradable plastics, pigments, and pharmaceuticals.

Magnetic polyimide nanocomposite for analysis of parabens in cooking wine by magnetic solid-phase extraction coupled with gas chromatography - Mass spectrometry.

A magnetic polyimide (PI) nanocomposite has been synthesized by phase inversion of PI and simultaneous encapsulation of Fe3O4 nanoparticles. The Fe3O4/PI nanocomposite was characterized by a variety of characterization techniques, including infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption isotherms, and vibrating sample magnetometry. The results showed that the prepared nanocomposite had a homogeneous structure, adequate specific surface area (76.1 m2/g) and high saturation magnetization (42.9 emu/g). Using parabens as model analytes, the performance of the Fe3O4/PI nanocomposite as an adsorbent for magnetic solid-phase extraction (MSPE) was evaluated. The extracted parabens were desorbed and determined by gas chromatography-mass spectrometry (GC-MS). The parameters affecting the extraction and desorption efficiency of parabens were optimized. Under the optimal conditions, the developed MSPE/GC-MS method was successfully applied to the determination of parabens in cooking wine. The MSPE/GC-MS method exhibited broad linearity (0.2-100 µg/L), low detection limits (0.04-0.05 µg/L), and satisfactory extraction recoveries (79.2 %-113.3 %) with relative standard deviations (RSDs) ranging from 0.7 % to 10.4 %. For real cooking wine samples, the spiked recoveries ranged from 91.7 % to 118.7 % with RSDs of 1.0 %-11.2 %. The results demonstrated that the Fe3O4/PI nanocomposite was an effective adsorbent, and this work provides a novel reference for the easy preparation of magnetic adsorbent materials.

Detrimental impacts and QSAR baseline toxicity assessment of Japanese medaka embryos exposed to methylparaben and its halogenated byproducts.

Despite the theoretical risk of forming halogenated methylparabens (halo-MePs) during water chlorination in the absence or presence of bromide ions, there remains a lack of in vivo toxicological assessments on vertebrate organisms for halo-MePs. This research addresses these gaps by investigating the lethal (assessed by embryo coagulation) or sub-lethal (assessed by hatching success/heartbeat rate) toxicity and teratogenicity (assessed by deformity rate) of MeP and its mono- and di-halogen derivatives (Cl- or Br-) using Japanese medaka embryos. In assessing selected apical endpoints to discern patterns in physiological or biochemical alterations, heightened toxic impacts were observed for halo-MePs compared to MeP. These include a higher incidence of embryo coagulation (4-36 fold), heartbeat rate decrement (11-36 fold), deformity rate increment (32-223 fold), hatching success decrement (11-59 fold), and an increase in Reactive Oxygen Species (ROS) level (1.2-7.4 fold)/Catalase (CAT) activity (1.7-2.8 fold). Experimentally determined LC50 values are correlated and predicted using a Quantitative Structure Activity Relationship (QSAR) based on the speciation-corrected liposome-water distribution ratio (Dlipw, pH 7.5). The QSAR baseline toxicity aligns well with (sub)lethal toxicity and teratogenicity, as evidenced by toxic ratio (TR) analysis showing TR < 10 for MeP exposure in all cases, while significant specific or reactive toxicity was found for halo-MeP exposure, with TR > 10 observed (excepting three values). Our extensive findings contribute novel insights into the intricate interplay of embryonic toxicity during the early-life-stage of Japanese medaka, with a specific focus on highlighting the potential hazards associated with halo-MePs compared to the parent compound MeP.

Exposure to endocrine disrupting chemicals (bisphenols, parabens, and triclosan) and their associations with preterm birth in humans.

Preterm birth in humans (PTB), defined as birth prior to 37 weeks of gestation, is one of the most important causes of neonatal morbidity and mortality and is associated with adverse health outcomes later in life. Attributed to many different etiological factors, estimated 15.1 million or 11.1% of births each year are preterm, which is more than 1 per 10 livebirths globally. Environmental pollution is a well-established risk factor that could influence the pathogenesis of PTB. Increasing evidence has shown an association between maternal exposure to endocrine disrupting chemicals (EDCs) and PTB. This scoping review aims to summarize current research on the association between EDC exposure and PTB in humans. Database PubMed was used to identify articles discussing the effect of selected EDCs, namely bisphenol A, bisphenol S, bisphenol F, parabens, and triclosan, found in plastics, cosmetics and other personal care products, on PTB occurrence. Regardless of some inconsistences in the findings across studies, the reviewed studies suggest a potential association between involuntary exposure to reviewed EDCs and the risk of PTB. However, further studies are needed to delineate exact correlations and mechanisms through which EDC exposure causes PTB so that efficient preventative measures could be implemented. Until then, health care providers should inform women about possible EDC exposure thus empowering them to make healthy choices and at the same time decrease the EDC negative effects.

Cardiovascular disrupting effects of bisphenols, phthalates, and parabens related to endothelial dysfunction: Review of toxicological and pharmacological mechanisms.

Cardiovascular diseases (CVDs) are the leading cause of death worldwide. CVDs are promoted by the accumulation of lipids and immune cells in the endothelial space resulting in endothelial dysfunction. Endothelial cells are important components of the vascular endothelium, that regulate the vascular flow. The imbalance in the production of vasoactive substances results in the loss of vascular homeostasis, leading the endothelial dysfunction. Thus, endothelial dysfunction plays an essential role in the development of atherosclerosis and can be triggered by different cardiovascular risk factors. On the other hand, the 17ß-estradiol (E2) hormone has been related to the regulation of vascular tone through different mechanisms. Several compounds can elicit estrogenic actions similar to those of E2. For these reasons, they have been called endocrine-disrupting compounds (EDCs). This review aims to provide up-to-date information about how different EDCs affect endothelial function and their mechanistic roles in the context of CVDs.

A large-scale survey of urinary parabens and triclocarban in the Chinese population as well as the influencing factors and health risks.

Parabens and triclocarban are widely applied as antimicrobial preservatives in foodstuffs, pharmaceuticals, cosmetics, and personal care products. However, few studies have been conducted on large-scale biomonitoring of parabens and triclocarban in the Chinese general population. In the present study, there were 1157 urine samples collected from 26 Chinese provincial capitals for parabens and triclocarban measurement to evaluate the exposure levels, spatial distribution, and influencing factors, as well as associated health risks in the Chinese population. The median concentrations of Σparabens and triclocarban were 14.0 and 0.03 µg/L, respectively. Methyl paraben was the predominant compound. Subjects in western China were more exposed to parabens, possibly due to climate differences resulting in higher consumption of personal care products. Subjects who were female, aged 18-44 years, or had a higher education level were found to have higher paraben concentrations. The frequency of drinking bottled water was positively associated with paraben exposure. The assessment of health risk based on urinary paraben concentrations indicated that 0.8 % of the subjects had a hazard index exceeding one unit, while Monte Carlo analysis suggested that 3.6 % of the Chinese population exposure to parabens had a potential non-carcinogenic risk. This large-scale biomonitoring study will help to understand the exposure levels of parabens and triclocarban in the Chinese general population and provide supporting information for government decision-making.

Parabens promotes invasive properties of multiple human cells: A potential cancer-associated adverse outcome pathway.

Parabens are esters of p-hydroxybenzoic acid, which have been used as preservatives and considered safe for nearly a century, until the last two decades when concerns began to be raised about their association with cancers. Knowledge of the mode of action of parabens on the metastatic properties of different cancer cells is still very limited. In the present study, we investigated the effects of methylparaben (MP) and propylparaben (PP) on cell invasion and/or migration in multiple human cancerous and noncancerous cells, including hepatocellular carcinoma cells (HepG2), cervical carcinoma cells (HeLa), breast carcinoma cells (MCF-7), and human placental trophoblasts (HTR-8/SVneo). MP and PP at concentrations in a range of 5-500 µg/L significantly promoted the invasion of four cell lines, with a minimum effective concentration of 5 µg/L. MP and PP up-regulated the expression levels and enzymatic activities of matrix metalloproteinase 2 and 9 (MMP2 and MMP9), as well as altered the expression of the tissue inhibitors of metalloproteinase 1 and 2 (TIMP1 and TIMP2) in four cell lines, suggesting MMPs/TIMPs as potential key events (KEs) for paraben-induced cell invasion. Activation of the p38 mitogen-activated protein kinase (p38 MAPK) and c-Jun N-terminal protein kinases 1/2 (JNK1/2) signaling pathways was required for MP- and PP-promoted invasion of four cell lines, suggesting MAPK signaling pathways as candidates for KEs in cancer or noncancerous cells response to paraben exposure. This study showed for the first time that the two widely used parabens, MP and PP, promoted invasive capacity of multiple human cells through a common mode of action. This study provides evidence for the establishment of a potential cancer-associated AOP for parabens based on pathway-specific mechanism(s), which contributes towards assessing the health risks of these environmental chemicals.

Estrogenic disruption effects and formation mechanisms of transformation products during photolysis of preservative parabens.

The ubiquitous presence of emerging contaminants (ECs) in the environment and their associated adverse effects has raised concerns about their potential risks. The increased toxicity observed during the environmental transformation of ECs is often linked to the formation of their transformation products (TPs). However, comprehension of their formation mechanisms and contribution to the increased toxicity remains an unresolved challenge. To address this gap, by combining quantum chemical and molecular simulations with photochemical experiments in water, this study investigated the formation of TPs and their molecular interactions related to estrogenic effect using the photochemical degradation of benzylparaben (BZP) preservative as a representative example. A non-targeted analysis was carried out and three previously unknown TPs were identified during the transformation of BZP. Noteworthy, two of these novel TPs, namely oligomers BZP-o-phenol and BZP-m-phenol, exhibited higher estrogenic activities compared to the parent BZP. Their IC50 values of 0.26 and 0.50 µM, respectively, were found to be lower than that of the parent BZP (6.42 µM). The binding free energies (ΔGbind) of BZP-o-phenol and BZP-m-phenol (-29.71 to -23.28 kcal·mol-1) were lower than that of the parent BZP (-20.86 kcal·mol-1), confirming their stronger binding affinities toward the estrogen receptor (ER) α-ligand binding domain. Subsequent analysis unveiled that these hydrophobic residues contributed most favorably to ER binding, with van der Waals interactions playing a significant role. In-depth examination of the formation mechanisms indicated that these toxic TPs primarily originated from the successive cleavage of ester bonds (OCH2C6H5 and COO group), followed by their combination with BZP*. This study provides valuable insight into the mechanisms underlying the formation of toxic TPs and their binding interactions causing the endocrine-disrupting effects. It offers a crucial framework for elucidating the toxicological patterns of ECs with similar structures.

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.

Endocrine disrupting effects of parabens in zebrafish (Danio rerio): New insights from transcriptomics, metabolomics, and molecular dynamics simulation.

Parabens (PBs), a group of widely used synthetic preservatives with potential endocrine disrupting activity, have been detected with increasing frequency in organisms and environmental matrices. This study assessed the hormone interference effects of four typical PBs, namely methylparaben (MeP), ethylparaben (EtP), propylparaben (PrP), and butylparaben (BuP), in zebrafish and elucidated the probable underlying mechanisms. Transcriptomic and metabolomic analyses showed that the differentially expressed genes and metabolites were associated with the tyrosine metabolism, arachidonate metabolism, and glycerophospholipid metabolism, indicating they were essential precursors of steroid hormone biosynthesis and metabolism. Histopathological analysis revealed impaired gonad development in the zebrafish exposed to PBs, as evidenced by the significantly increased vitellogenin (VTG) and estradiol (E2) levels. Furthermore, molecular dynamics simulation suggested that the four PBs could preferentially activate the zebrafish estrogen receptor, zfERß2, to regulate the downstream pathways. Disruption of the amino acid metabolism and lipid metabolism, and activation of zfERß2 signaling pathway were found to be the key mechanisms for the endocrine disrupting effects of PBs. The hormone interference effects of PBs were apparently dependent on the shared oxybenzene on their structures, with the degree of interference determined largely by the length of their alkyl chains. These findings provide new insights into the endocrine disrupting effects of PBs and could help better assess their risk to human health.

Disruption of gonadotropin hormone biosynthesis by parabens: A potential development and reproduction-associated adverse outcome pathway.

Parabens are widely used as antibacterial preservatives in foods and personal care products. The knowledge about the modes of toxic action of parabens on development and reproduction remain very limited. The present study attempted to establish a development and reproduction-associated adverse outcome pathway (AOP) by evaluating the effects of methylparaben (MP), ethylparaben (EP), propylparaben (PP) and butylparaben (BP) on the biosynthesis of gonadotropins, which are key hormones for development and reproduction. MP and BP significantly upregulated the mRNA and protein levels of follicle stimulating hormone (FSH) and luteinizing hormone (LH) in pituitary gonadotropic cells in a concentration-dependent manner. Activation of gonadotropin-releasing hormone receptor (GnRHR) was required for gonadotropin biosynthesis induced by BP, but not MP. Molecular docking data further demonstrated the higher binding efficiency of BP to human GnRHR than that of MP, suggesting GnRHR as a potential molecular initiative event (MIE) for BP-induced gonadotropin production. L-type voltage-gated calcium channels (VGCCs) were found to be another candidate for MIE in gonadotropic cells response to both MP and BP exposure. The calcium-dependent activation of extracellular signal-regulated kinase 1 (ERK1) and ERK2 was subsequently required for MP- and BP-induced activation of GnRHR and L-type VGCCs pathways. In summary, MP and BP promoted gonadotropin biosynthesis through their interactions with cellular macromolecules GnRHR, L-type VGCCs, and subsequent key event ERK1/2. This is the first study to report the direct interference of parabens with gonadotropin biosynthesis and establish a potential AOP based on pathway-specific mechanism, which contributes to the effective screening of environmental chemicals with developmental and reproductive health risks.

Microbiological insights into anaerobic phenol degradation mechanisms and bulking phenomenon in a mesophilic upflow anaerobic sludge blanket reactor in long-term operation.

In this study, a long-term operation of 2,747 days was conducted to evaluate the performance of the upflow anaerobic sludge blanket (UASB) reactor and investigated the degradation mechanisms of high-organic loading phenol wastewater. During the reactor operation, the maximum chemical oxygen demand (COD) removal rate of 6.1 ± 0.6 kg/m3/day under 1,680 mg/L phenol concentration was achieved in the mesophilic UASB reactor. After a significant change in the operating temperature from 24.0 ± 4.1 °C to 35.9 ± 0.6 °C, frequent observations of floating and washout of the bloated granular sludge (novel types of the bulking phenomenon) were made in the UASB reactor, suggesting that the change in operating temperature could be a trigger for the bulking phenomenon. Through the metagenomic analysis, phenol degradation mechanisms were predicted that phenol was converted to 4-hydroxybenzoate via two possible routes by Syntrophorhabdaceae and Pelotomaculaceae bacteria. Furthermore, the degradation of 4-hydroxybenzoate to benzoyl-CoA was carried out by members of Syntrophorhabdaceae and Smithellaceae. In the bulking sludge, a predominant presence of Nanobdellota, belonging to DPANN archaea, was detected. The metagenome-assembled genome of the Nanobdellota lacks many biosynthetic pathways and has several genes for the symbiotic lifestyle such as trimeric autotransporter adhesin-related protein. Furthermore, the Nanobdellota have significant correlations with several methanogenic archaea that are predominantly present in the UASB reactor. Considering the results of this study, the predominant Nanobdellota may negatively affect the growth of the methanogens through the parasitic lifestyle and change the balance of microbial interactions in the granular sludge ecosystem.