Mono-cyclohexyl Phthalate Research Articles

Prenatal co-exposure to phthalate metabolites and bisphenols among non-syndromic cleft lip and/or palate in offspring

Phthalate metabolites and bisphenols can cause adverse pregnancy outcomes. However, there is no study to evaluate the associations of prenatal exposure to phthalate metabolites and bisphenols with non-syndromic cleft lip and/or palate (NSCL/P) risk in offspring. A population-based case-control study was conducted in a multicenter setting from 2005 to 2021, enrolling 448 pregnant women. Seven phthalate metabolites and six bisphenols were quantified in placenta using liquid chromatography-tandem mass spectrometry. In the logistic regression analysis, high levels of mono-ethyl phthalate, mono-cyclohexyl phthalate, mono-octyl phthalate, bisphenol A, bisphenol AF, bisphenol AP, and fluorene-9-bisphenol were associated with increased NSCL/P risk with odds ratios (95% confidence intervals) of 1.86(1.07,3.25), 6.56(3.47,12.39), 8.49(4.44,16.24), 8.34(4.32,16.08), 3.19(1.81,5.62), 2.78(1.59,4.86), and 5.16(2.82,9.44). The Bayesian kernel machine regression model revealed that co-exposure to phthalate metabolites and bisphenols was associated with increased NSCL/P risk. Similarly, quantile-based g-computation analysis indicated that each quantile increase in mixture concentration was positively related to higher risk for NSCL/P [odds ratio (95% confidence interval) = 2.98(1.97,4.51)]. This study provides novel evidence that prenatal single and co-exposure to phthalate metabolites and bisphenols were associated with increased NSCL/P risk, suggesting that exposure to phthalate metabolites and bisphenols during pregnancy should be minimized to reduce the incidence of NSCL/P in offspring.

Concentration levels of phthalate metabolites in wild boar hair samples

Phthalates used in the industry penetrate the environment and negatively affect humans and animals. Hair samples seem to be the best matrix for studies on long-term exposure to phthalates, but till now they were used only in investigations on humans. Moreover, the knowledge of the wild terrestrial animal exposure to phthalates is extremely limited. This study aimed to establish of concentration levels of selected phthalate metabolites (i.e. monomethyl phthalate—MMP, monoethyl phthalate—MEP, mono-isobutyl phthalate—MiBP, monobutyl phthalate—MBP, monobenzyl phthalate—MBzP, mono-cyclohexyl phthalate—MCHP, mono(2-ethylhexyl) phthalate—MEHP and mono-n-octyl phthalate—MOP) in wild boar hair samples using liquid chromatography with mass spectrometry (LC–MS) analysis. MEHP was noted in 90.7% of samples with mean 66.17 ± 58.69 pg/mg (median 49.35 pg/mg), MMP in 59.3% with mean 145.1 ± 310.6 pg/mg (median 64.45 pg/mg), MiBP in 37.0% with mean 56.96 ± 119.4 pg/mg (median < limit of detection—LOD), MBP in 35.2% with mean 19.97 ± 34.38 pg/mg (median < LOD) and MBzP in 1.9% with concentration below limit of quantification. MEP, MCHP, and MOP have not been found in wild boar hair samples during this study. The results have shown that wild boars are exposed to phthalates and hair samples may be used as a matrix during studies on levels of phthalate metabolites in wild animals.

Differential Disruption of Glucose and Lipid Metabolism Induced by Phthalates in Human Hepatocytes and White Adipocytes.

Phthalic acid esters (PAEs), commonly used as plasticizers, are pervasive in the environment, leading to widespread human exposure. The association between phthalate exposure and metabolic disorders has been increasingly recognized, yet the precise biological mechanisms are not well-defined. In this study, we explored the effects of monoethylhexyl phthalate (MEHP) and monocyclohexyl phthalate (MCHP) on glucose and lipid metabolism in human hepatocytes and adipocytes. In hepatocytes, MEHP and MCHP were observed to enhance lipid uptake and accumulation in a dose-responsive manner, along with upregulating genes involved in lipid biosynthesis. Transcriptomic analysis indicated a broader impact of MEHP on hepatic gene expression relative to MCHP, but MCHP particularly promoted the expression of the gluconeogenesis key enzymes G6PC and FBP1. In adipocytes, MEHP and MCHP both increased lipid droplet formation, mimicking the effects of the Peroxisome proliferator-activated receptor γ (PPARγ) agonist rosiglitazone (Rosi). Transcriptomic analysis revealed that MEHP predominantly altered fatty acid metabolism pathways in mature adipocytes (MA), whereas MCHP exhibited less impact. Metabolic perturbations from MEHP and MCHP demonstrate shared activation of the PPARs pathway in hepatocytes and adipocytes, but the cell-type discrepancy might be attributed to the differential expression of PPARγ. Our results indicate that MEHP and MCHP disrupt glucose and lipid homeostasis in human liver and adipose through mechanisms that involve the PPAR and adenosine monophosphate-activated protein kinase (AMPK) signaling pathways, highlighting the nuanced cellular responses to these environmental contaminants.

Risk analysis of serum chemical residues for metabolic associated fatty liver disease based on exposome-lipidome wide association study

Metabolic associated fatty liver disease (MAFLD) is a common liver disease with a prevalence of up to 25%; it not only adversely affects human health but also aggravates the economic burden of society. An increasing number of studies have suggested that the occurrence of chronic noncommunicable diseases is affected by both environmental exposures and genetic factors. Research has also shown that environmental pollution may increase the risk of MAFLD and promote its occurrence and development. However, the relationship between these concepts, as well as the underlying exposure effects and mechanism, remains incompletely understood. Lipidomics, a branch of metabolomics that studies lipid disorders, can help researchers investigate abnormal lipid metabolites in various disease states. Lipidome-exposome wide association studies are a promising paradigm for investigating the health effects of cumulative environmental exposures on biological responses, and could provide new ideas for determining the associations between metabolic and lipid changes and disease risk caused by chemical-pollutant exposure. Hence, in this study, targeted exposomics and nontargeted lipidomics studies based on ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) were used to characterize exogenous chemical pollutants and endogenous lipid metabolites in the sera of patients with MAFLD and healthy subjects. The results demonstrated that fipronil sulfone, malathion dicarboxylic acid, and monocyclohexyl phthalate may be positively associated with the disease risk of patients diagnosed as simple fatty liver disease (hereafter referred to as MAFLD(0)). Moreover, fipronil sulfone, acesulfame potassium, perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluoroundecanoic acid (PFUnDA), 4-hydroxybenzophenone, and 3,5-di-tert-butyl-4-hydroxybenzoic acid (DBPOB) may be positively associated with the disease risk of patients diagnosed as fatty liver complicated by single or multiple metabolic disorders. Association analysis was carried out to explore the lipid metabolites induced by chemical residues. Triglyceride (TG) and diglyceride (DG) were significantly increased in MAFLD and MAFLD(0). The numbers of carbons of significantly changed DGs and TGs were mainly in the ranges of 32-40 and 35-60, respectively, and both were mainly characterized by changes in polyunsaturated lipids. Most of the lipid-effect markers were positively correlated with chemical residues and associated with increased disease risk. Our research provides a scientific basis for studies on the association and mechanism between serum chemical-pollutant residues and disease outcomes.

Measurement of 24 phthalate metabolites in 1st trimester urine samples: The MIREC study

Phthalates are non-persistent chemicals measured as metabolites in urine. Over time, new metabolites have been identified. In the original Maternal-Infant Research on Environmental Chemicals (MIREC) study (2008–2011), we measured 11 phthalate metabolites in first trimester urine samples. The goal of the present study was to develop a method to measure new metabolites, to increase the sensitivity for some previously measured metabolites, and to measure these new metabolites in biobanked urine samples from MIREC participants.Using Ultra Performance Liquid Chromatography with a tandem mass spectrometer, we developed a method to measure 24 metabolites from 10 different parent phthalates. Chromatographic interpretation of some of the di-iso-decyl phthalate metabolites (mono-(2-propyl-6oxoheptyl) phthalate (MOiDP), mono-(2,7-methyl-7-carboxyheptyl) phthalate (MCiNP), mono-(2-propyl-6-hydroxy-heptyl) phthalate (MHiDP)) and di-iso-nonyl phthalate metabolites (mono(oxo-isononyl) phthalate (MOiNP), mono(carboxy-isooctyl) phthalate (MCiOP), mono(hydroxy-isononyl) phthalate (MHiNP) and mono-isononyl phthalate (MiNP)) was challenging as these are complex isomeric mixtures.To validate and confirm our quantitation peaks, an assay using a high-resolution detection technique was developed on a Quadrupole Time-of-Flight (QToF) system. This system has a mass resolution of at least 0.005 amu, compared to 0.5 amu for the MS/MS detector. Using the QToF system, the distinction between an isomer and possible interference was achieved with the use of the exact mass.In about 1800 MIREC samples, mono-cyclo-hexyl phthalate (MCHP), mono-(7-carboxy-n-heptyl) phthalate (MCHpP), mono-iso-decyl phthalate (MiDP), and mono-n-octyl phthalate (MnOP) were rarely detected, while detection of MMP was improved. MCiOP, MiNP and MCiNP had to be reported semi-quantitatively.Given the complexity of isomeric mixtures of some phthalates, researchers must be careful in their determination of the analytes and the approach used in their quantification when generating biomonitoring data.This study produced biomonitoring data for a large population of pregnant people that can be used in risk assessment of phthalates. Future work will examine associations with birth and child outcomes.

Inhibition of Human Sulfotransferases by Phthalate Monoesters.

ObjectiveThis study aimed to investigate the inhibition of human important phase II metabolic enzyme sulfotransferases (SULTs) by phthalate monoesters, which are important metabolites of phthalate esters (PAEs).MethodRecombinant SULT-catalyzed metabolism of p-nitrophenol (PNP) was employed as the probe reactions of SULTs to investigate the inhibition of 8 kinds of phthalate monoesters towards SULT isoforms. An in vitro incubation system was utilized for preliminary screening, and 100 μM of phthalate monoesters was used. Inhibition kinetics were carried out to determine the inhibition of SULTs by phthalate monoesters.ResultMultiple phthalate monoesters have been demonstrated to exert strong inhibition potential towards SULT1A1, SULT1B1, and SULT1E1, and no significant inhibition of phthalate monoesters towards SULT1A3 was found. The activity of SULT1A1 was strongly inhibited by mono-hexyl phthalate (MHP), mono-octyl phthalate (MOP), mono-benzyl phthalate (MBZP), and mono-ethylhexyl phthalate (MEHP). Monobutyl phthalate (MBP), MHP, MOP, mono-cyclohexyl phthalate (MCHP), and MEHP significantly inhibited the activity of SULT1B1. MHP, MOP, and MEHP significantly inhibited the activity of SULT1E1. MOP was chosen as the representative phthalate monoester to determine the inhibition kinetic parameters (K i) towards SULT1B1 and SULT1E1. The inhibition kinetic parameters (K i) were calculated to be 2.23 μM for MOP-SULT1B1 and 5.54 μM for MOP-SULT1E1. In silico docking method was utilized to understand the inhibition mechanism of SULT1B1 by phthalate monoesters.ConclusionsAll these information will be beneficial for understanding the risk of phthalate monoester exposure from a new perspective.

Comprehensive insights into the interactions of dicyclohexyl phthalate and its metabolite to human serum albumin

Phthalate esters (PAEs) are a type of persistent organic pollutants and have received widespread concerns due to their adverse effects on human health. Dicyclohexyl phthalate (DCHP) and its metabolite monocyclohexyl phthalate (MCHP) were selected to explore the mechanism for interaction of PAEs with human serum albumin (HSA) through molecular docking and several spectroscopic techniques. The results showed that DCHP/MCHP can spontaneously occupy site I to form a binary complex with HSA, and DCHP exhibited higher binding affinity to HSA than MCHP. At 298 K, the binding constants (Kb) of DCHP and MCHP to HSA were 24.82 × 104 and 1.04 × 104 M−1, respectively. Hydrogen bonds and van der Waals forces were the major driving forces in DCHP/MCHP–HSA complex. The presence of DCHP/MCHP induced the secondary structure changes in HSA, and the pi electrons of the benzene ring skeleton of DCHP/MCHP played a key role in this binding processes. Exposure of DCHP/MCHP to TM4 cells revealed that interactions between PAEs and serum albumin can affect their cytotoxicity; DCHP showed higher toxicity than MCHP. The binding affinity of PAEs with HSA may be a valuable parameter for rapid assessment of their toxicity to organisms.

Concentrations of Seven Phthalate Monoesters in Infants and Toddlers Quantified in Urine Extracted from Diapers.

Carrying out exposure studies on children who are not toilet trained is challenging because of the difficulty of urine sampling. In this study, we optimized a protocol for urine collection from disposable diapers for the analysis of phthalate metabolites. The exposure of Swiss children (n = 113) between 6 months and 3 years of life to seven phthalates was assessed by gas chromatography–mass spectrometry measurements. The study showed limited exposures to phthalates, with only 22% of the samples containing some of the metabolites investigated. The three most frequently detected metabolites were monoethyl phthalate, mono-cyclohexyl phthalate, and mono-benzyl phthalate. We also detected mono-n-octyl phthalate and mono(3,5,5-trimethylhexyl) phthalate, which have rarely been observed in urine from infants and toddlers; therefore, di-n-octyl phthalate and bis(3,5,5-trimethylhexyl) phthalate can be considered as potentially new emerging phthalates. This study presents an initial snapshot of the Swiss children’s exposure to phthalates and provides a promising approach for further phthalate biomonitoring studies on young children using disposable diapers as urine sampling technique.

Associations between Potential Exposure Sources and Urinary Phthalate Concentrations among Couples Undergoing Infertility Treatment

Background/Aim: Phthalates are implicated as reproductive toxicants in experimental and observational studies. We examined associations between potential exposure sources and urinary phthalate concentrations among infertile couples.Methods: Women (n=56) and their male partners (n=43) undergoing in vitro fertilization (IVF) were enrolled in a prospective cohort investigation of environmental chemicals and IVF outcomes. On the day of oocyte retrieval, women (fasting) and their male partners provided urine samples and completed questionnaires detailing use of personal care products (PCPs), consumption of medications, and foods/beverages in the preceding 24-hours. Urine was analyzed for monoethyl phthalate (MEP), mono-n-butyl phthalate (MBP), mono-n-pentyl phthalate (MPP), mono-n-hexyl phthalate (MHxP), mono(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP), mono-isononyl phthalate (MiNP), mono-isodecyl phthalate (MiDP), monocyclohexyl phthalate (MCHP), and monobenzyl phthalate (MBzP) via liquid chromatography-tandem mass spectrometry (Agilent LC 1260-AB Sciex 5500). We employed principal component analysis (PCA) to summarize questionnaire responses as patterns of exposure and entered factors into linear regression models to evaluate associations with urinary phthalate concentrations, adjusted for specific gravity, age, BMI (for women), history of smoking, and race. Results: Among women, recent application of moisturizers, cleansers, and nail polish was associated with greater urinary MBP [β=0.08 (95% CI: 0.02-0.14)] and the molar sum of diethylhexyl phthalate (DEHP) metabolites [β=0.23 (95% CI: 0.16-0.29)]. Among men, recent supplement and allergy medication intake was positively associated with the sum of DEHP metabolites [β=0.12 (95% CI: 0.02-0.21)]. Women with a tubal factor or polycystic ovarysyndrome infertility diagnosis had higher urinary phthalate concentrations than women with other infertility diagnoses.Conclusions: Among women, recent PCP use predicted urinary phthalate concentrations, whereas in men, supplements/medications were important contributors to phthalate exposure. This difference in exposure sources among couples will be useful for developing strategies to limit phthalate exposure as part of a comprehensive strategy to help improve IVF outcomes.

Associations between Preconception Phthalate Exposure and Infertility Treatment Outcomes among Couples Undergoing In Vitro Fertilization

Background/Aim: Phthalates are implicated as reproductive toxicants in animal models and human populations. We modeled associations between couples’ preconception phthalate exposures and in vitro fertilization (IVF) outcomes.Methods: Women (n=56) and their male partners (n=43) undergoing IVF were enrolled in a prospective cohort investigation of environmental exposures and reproductive outcomes. Participants provided urine samples (fasting for women) on the day of oocyte retrieval. Urine was analyzed for monoethyl phthalate (MEP), mono-n-butyl phthalate (MBP), mono-n-pentyl phthalate (MPP), mono-n-hexyl phthalate (MHxP), mono(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP), mono-isononyl phthalate (MiNP), mono-isodecyl phthalate (MiDP), monocyclohexyl phthalate (MCHP), and monobenzyl phthalate (MBzP) via liquid chromatography-tandem mass spectrometry (Agilent LC 1260-AB Sciex 5500). Modified Poisson regression models, were used to assess associations between IVF outcomes and individual urinary phthalates among women and men separately, and simultaneously in couples, adjusted for age, body mass index (for women), and cigarette smoking. Results: Individual partner models showed higher likelihoods of pregnancy and live birth associated with greater concentrations of several urinary phthalates, albeit without statistical significance, with the exception of men’s MEHP and pregnancy [RR=0.53 (95%CI: 0.24-1.17). However, most urinary phthalates were associated with lower chances of pregnancy and live birth among couples. A doubling in women’s MBP was associated with a 43% [RR=0.57 (95%CI: 0.36-0.91)] lower likelihood of a pregnancy and a 46% [RR=0.54 (95%CI: 0.27-1.08)] lower likelihood of a live birth, adjusted for the male partner. Doublings in men’s MEHP andMEP were associated with 66% [RR=0.34 (95% CI: 0.16-0.72)] and 28% [RR=0.72 (95% CI: 0.52-1.01)] lower likelihoods of a pregnancy, respectively, adjusted for the female partner. Conclusions: Greater urinary MEP, MBP, and MEHP were associated with lower probabilities of pregnancy and live birth among couples undergoing IVF. The results suggest that greater phthalate exposure in couples may be deleterious to IVF.

Is there a difference in the phthalate exposure between adults with metabolic disorders and healthy ones?

Background/Aim. Phthalates are recognized as endocrine-disrupting compounds and are extensively present in a variety of everyday products. Chronic exposure to phthalates is suspected to be associated with a range of health disorders. The aim of the study was to examine the abundance of phthalate metabolites in the urine samples among adults in the Autonomous Province of Vojvodina, Serbia, and to determine the prevalence of phthalate metabolites in healthy individuals and those with metabolic disorders such as obesity and newly diagnosed type 2 diabetes mellitus (T2DM). Methods. For the study purpose, the first morning urine sample of 308 participants was screened for the presence of 10 phthalate metabolites: mono-ethyl phthalate (MEP), mono-(2-ethylhexyl) phthalate (MEHP), mono-n-butyl phthalate (MBP), mono-iso-allyl phthalate (MiAP), mono-n-allyl phthalate (MnAP), mono-cyclohexyl phthalate (MCHP), mono-benzyl phthalate (MBzP), mono-n-octyl phthalate (MOP), mono-n-propyl phthalate (MPP) and mono-methyl phthalate (MMP). Results. At least one phthalate metabolite was detected in the first morning urine sample in 50.32% of the examined population. The most frequently detected phthalate metabolites were MEP and MEHP. Out of all phthalate-positive participants, 38.3% of them had one, 10.7% had two, while 1.3% of participants had three phthalate metabolites in the first morning urine sample. A significant difference (p &lt; 0.05) between groups was observed on MEP and MMP frequency, while border-line significant difference (p &lt; 0.1) between groups was observed on MEHP and MCHP frequency. Conclusion. In the Vojvodina region, both healthy adults and those with metabolic disorders such as obesity and newly diagnosed T2DM are predominantly exposed to di-ethyl phthalate and di-(2-ethylhexyl)phthalate since MEP and MEHP were the most frequently detected phthalate metabolites. Further re-search is required in order to provide more details of the phthalates influence on the adverse health effects.

A rapid method for the quantification of urinary phthalate monoesters: A new strategy for the assessment of the exposure to phthalate ester by solid-phase microextraction with gas chromatography and tandem mass spectrometry.

In the following work, a new method for the analysis of the phthalate monoesters in human urine was reported. Phthalate monoesters are metabolites generated as a result of phthalate exposure. In compliance with the dictates of Green Analytical Chemistry, a rapid and simple protocol was developed and optimized for the quantification of phthalate monoesters (i.e., monoethyl phthalate, monoisobutyl phthalate, mono-n-butyl phthalate, mono-(2-ethylhexyl) phthalate, mono-n-octyl phthalate, monocyclohexyl phthalate, mono-isononyl phthalate) in human urine, which entails preceding derivatization with methyl chloroformate combined with the use of commercial solid phase microextraction and the analysis by gas chromatography-triple quadrupole mass spectrometry. The affinity of the derivatized analytes toward five commercial coatings was evaluated, and in terms of analyte extraction, the best results were reached with the use of the divinylbenzene/carboxen/polydimethylsiloxane fiber. The multivariate approach of experimental design was used to seek for the best working conditions of the derivatization reaction and the solid phase microextraction, thus obtaining the optimum response values. The proposed method was validated according to the guidelines issued by the Food and Drug Administration achieving satisfactory values in terms of linearity, sensitivity, matrix effect, intra- and inter-day accuracy, and precision.

Concentrations of phthalate metabolites in Australian urine samples and their contribution to the per capita loads in wastewater

Exposure to phthalates is a public health concern. In this study, we collected both urine and wastewater samples from 2012 to 2017 and analysed for 14 phthalate metabolites to assess human exposure to phthalates in Southeast Queensland (SEQ), and for associations between phthalate metabolites in urine and wastewater samples. Twenty-four pooled urine samples were prepared from 2400 individual specimens every two years (stratified by age, gender and collection year). Wastewater samples were collected from the three major wastewater treatment plants (WWTPs) representing locations in the SEQ region including a regional city, part of the state capital city and a third major urban WWTP in the region. Over the period, decreases for most phthalate metabolites, i.e. mono-butyl phthalate (MBP), mono-isobutyl phthalate (MiBP), monobenzyl phthalate (MBzP), monocyclohexyl phthalate (MCHP), mono(3-carboxypropyl) phthalate (MCPP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), and monomethyl phthalate (MMP), but an increase in monoethyl phthalate (MEP, particularly in young children) were observed in urine. In general, temporal changes were smaller in urine pools representing older age groups. We also found substantial variation in per capita mass loads of phthalate metabolites between samples from the three WWTPs with generally higher concentrations of most phthalates in the metropolitan areas. Per capita mass loads of most phthalate metabolites in wastewater were higher than would be expected from the per-capita excretion in urine, suggesting there are additional sources contributing to the majority of the observed phthalate metabolites in wastewater. For MEHHP and MEOHP we estimate that the urinary excretion accounts for a substantial fraction (average about 50%) of the mass load observed in the wastewater hence wastewater data may provide useful for monitoring trends in exposure.

Phthalate exposures are associated with Staphylococcus aureus nasal colonization in the U.S. population

PDS 75: Microbiome, infections and respiratory effects, Johan Friso Foyer, Floor 1, August 27, 2019, 1:30 PM - 3:00 PM Background/Aim: There are emerging concerns that endocrine disrupting chemicals (EDCs) with immunomodulatory properties could attenuate immunity against infections and alter disease outcomes. A related concern is the potential for EDCs with antimicrobial properties to select for drug-resistant pathogens. Phthalates are EDCs with immunomodulatory and antimicrobial properties; however, the potential impacts of phthalate exposures on Staphylococcus aureus (SA) colonization have not been explored. Methods: We used publicly-available 2001-2004 data on 5303 participants (6-85 years) from the U.S. population-based National Health and Nutrition Examination Survey (NHANES). Exposures to 12 phthalate metabolites were quantified in urine samples and SA nasal colonization was detected using microbial culture. Measured Di(2-ethylhexyl) phthalate (DEHP) metabolites were summed by molecular weight. We used survey-weighted and covariate-adjusted logistic regression models to examine associations between SA colonization and phthalate exposures. Results: A total of 1637 (30%) participants had detectable SA nasal colonization. Increasing concentrations of the two high-molecular-weight phthalates—Mono-(3-carboxypropyl) phthalate (MCPP) and ∑DEHP—were associated with SA colonization; e.g. participants had 14% higher odds of SA nasal colonization with each log10 increase in MCPP [95% Confidence Interval (CI) 1.05, 1.23, p≤0.001]. Three of seven low-molecular-weight phthalates—Mono-benzyl (MBzP), Mono-isobutyl (MiBP) and Mono-cyclo-hexyl phthalate (MCHP)—were associated with SA colonization; e.g. participants had 17% higher odds of SA nasal colonization with each log10 increase in MBzP [95% CI: 1.05, 1.32, p≤0.008]. Conclusions: Phthalates, particularly high-molecular-weight phthalates that may be found in building materials, are associated with SA nasal colonization in the U.S. population. SA nasal colonization increases infection risk. Further, exposure to phthalates and SA nasal colonization are factors known to be associated with similar chronic disease outcomes, such as asthma and wheeze. Future studies are needed to identify if there is a casual relationship between phthalate exposure and SA nasal colonization and if such joint exposures impact disease outcomes.

Molecular docking and simulation analysis for elucidation of toxic effects of dicyclohexyl phthalate (DCHP) in glucocorticoid receptor-mediated adipogenesis

ABSTRACT‘Obesogens’ are chemical agents that improperly regulate the genes involved in glucose metabolism and adipocyte differentiation and promote lipid accumulation and adipogenesis. The human glucocorticoid receptor (hGR) is a steroid hormone triggered transcriptional factor and regulates target genes important in basal glucose homeostasis. Molecular docking analysis was performed in order to assess in-silico structure based toxic effects of high molecular weight phthalates dicyclohexyl phthalate (DCHP) and its monophthalate metabolite mono-cyclohexyl phthalate (MCHP). Molecular docking results show that the binding affinities of DCHP and MCHP lie in the comparable range (−7.87 kcal/mol and −6.24 kcal/mol) with Dexamethasone (−10.2 kcal/mol), a potent agonist for hGR. These two PAEs occupy the active site of hGR and interact with the key residues. Molecular simulation results infer that hGR-PAEs complexes were stable. Density functional theory (DFT) analysis indicates that HOMO and LUMO energy gap of DCHP (3.88 eV) and MCHP (3.39 eV) are comparable to DEX (4.69 eV). Binding free energy calculations of the DCHP-hGR and MCHP-hGR complexes were estimated by using Molecular Mechanic/Poisson-Boltzmann Surface Area (MMPBSA) method. Molecular Docking and simulation results emphasise that DCHP and MCHP can efficiently bind to hGR, which further leads to glucocorticoid-mediated adipogenesis in a synergistic manner.

Study of possible association between endometriosis and phthalate and bisphenol A by biomarkers analysis

Endocrine disrupting chemicals (EDCs) such as phthalates and bisphenol A (BPA) are substances that may interfere with the actions of endogenous hormones and may be associated with estrogen-related diseases such as endometriosis. This paper describes a case-control study to evaluate the relationship between endometriosis and phthalates and BPA exposure, through biomarkers analysis in urine. The biomarkers of exposure analyzed were metabolites mono-methyl phthalate, mono-isobutyl phthalate (MiBP), mono-butyl phthalate, mono-cyclohexyl phthalate, mono-(ethylhexyl) phthalate, mono-isononyl phthalate, mono-octyl phthalate (MOP), mono-benzyl phthalate and BPA. Urine samples were collected from women aged 18–45 years old. The Study group (n = 30) and Control group (n = 22) were composed of women using as criteria confirmation of endometriosis by videolaparoscopy surgery with histological diagnosis and the absence of the disease, respectively. The analytical method used liquid phase microextraction with determination by gas chromatography coupled to mass spectrometry. The concentrations of biomarkers were adjusted by the creatinine concentration in urine samples of the two groups. The values obtained for the Study Group were compared with the values obtained for the Control Group. The chi-square test and Odds Ratio were used to compare dichotomized phthalate metabolites and BPA metabolite by endometriosis. All nine metabolites were found in different concentrations in the urine samples in both groups The phthalate metabolites that had the highest concentrations, were MOP and MiBP, in which the values of 670 μg g−1 and 560 μg g−1, respectively. The relationship between endometriosis and the all grouped metabolites was evaluated, but was not statistically significant with a 95% CI [X2 (df = 1) = 1.471; p = 0.225]. However, odds ratio (95% confidence interval - CI) for MiBP, which was found at relatively high concentrations in the samples, by endometriosis was 1.929 (0.507–7.332). The food habits and gynecologic history were evaluated and no difference was found between groups. Although no evidences of causal link was found, this study contributes to show that other analysis must be done for evaluating the association between endometriosis and compounds suspected of being EDC.

Urinary phthalate metabolites among children in Saudi Arabia: Occurrences, risks, and their association with oxidative stress markers

Phthalates have been used as plasticizers in numerous consumer applications and therefore, their metabolites have been detected in human urine worldwide. Despite concerns regarding their potential adverse health effects, few exposure assessments have been conducted among young populations in Middle Eastern countries. In this study, children (n = 109, aged 3–9 years) were recruited from four elementary schools in Riyadh, Saudi Arabia, in 2017, and major phthalate metabolites were measured in their urine. Their parents were asked to complete a questionnaire on their behalf to assess potential exposure sources of phthalates. In addition to 18 phthalate metabolites, malondialdehyde (MDA) and 8-hydroxy-2′-deoxyguanosine (8-OHdG) were measured in urine samples by LC/MS/MS. Among the children of Saudi Arabia, urinary levels of monoisobutyl phthalate (MiBP) and monobutyl phthalate (MnBP) were higher than those reported previously in children worldwide. Monoethyl phthalate (MEP) was also detected at high levels. Several phthalate metabolites showed significant associations with the levels of MDA or 8-OHdG. Hazard quotients (HQs) derived for certain phthalates were greater than one. In particular, the HQs for di(2-ethylhexyl) phthalate (DEHP) were greater than one in 34% of the participating children. Levels of monocyclohexyl phthalate (MCHP), monoisodecyl phthalate (MiDP), mono(2-ethylhexyl) phthalate (MEHP), and mono[2-(carboxymethyl)hexyl] phthalate (MCMHP) in the urine samples were positively associated with the consumption frequency of certain foods. Very high levels of exposure to phthalates, along with positive associations with oxidative stress markers, outline the importance of follow-up investigations for identification of phthalate exposure sources and potential health implications among the young population of Saudi Arabia.

Austrian reference values for phthalate metabolite exposure in children/adolescents and adults

Reference values (RV95) are statistically derived values comprising the rounded 95th percentiles within the 95% confidence interval and indicate the upper margin of background exposure to chemical substances in a population at a given time period. Based on representative national human biomonitoring data on several urinary phthalate metabolites in children, adolescents and adults from 2010 to 2011, RV95 were derived for the Austrian population based on a IUPAC guideline and the recommendation of the German Human Biomonitoring Commission. The RV95 (rounded values) for phthalate metabolites in children and adolescents aged 6-15 years are 110 μg/l (confidence interval of 95th population percentile: 83.7-163) for mono-ethyl phthalate (MEP), 45 μg/l (40.9-60.6) for mono-n-butyl phthalate (MnBP), 130 μg/l (126-161) for mono-isobutyl phthalate (MiBP), 25 μg/l (17.8-33.6) for mono-benzyl phthalate (MBzP), 100 μg/l (94.0-126) for the sum of the di(2-ethylhexyl) phthalate (DEHP) metabolites including mono(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (5OH-MEHP), mono(2-ethyl-5-oxohexyl) phthalate (5oxo-MEHP) and mono(2-ethyl-5-carboxypentyl) phthalate (5cx-MEPP), and 1.5 μg/l (0.64-1.6) for mono-cyclohexyl phthalate (MCHP). In adults aged 18-81 years, RV95 are 440 μg/l (353-636) for MEP, 40 μg/l (33.1-52.1) for MnBP, 110 μg/l (87.3-118) for MiBP, 10 μg/l (7.2-11.8) for MBzP, 50 μg/l (44.6-68.3) for the sum of MEHP, 5OH-MEHP, 5oxo-MEHP and 5cx-MEPP, and 1.5 μg/l (0.95-1.8) for MCHP. For almost all investigated metabolites, children and adolescents exhibit higher RV95 than adults, with the exceptions being MEP and MCHP. Compared to available RV95 for Germany and Canada, Austrian values are lower for all investigated population groups.

Inhibition of UDP-glucuronosyltransferases (UGTs) by phthalate monoesters

Phthalate monoesters are important metabolites of phthalate esters (PAEs) which have been extensively utilized in industry. This study aims to investigate the inhibition of phthalate monoesters on the activity of various isoforms of UDP-glucuronosyltransferases (UGTs), trying to elucidate the toxicity mechanism of environmental endocrine disruptors from the new perspectives. In vitro recombinant UGTs-catalyzed glucuronidation of 4-methylumbelliferone (4-MU) was employed to evaluate 8 kinds of phthalate monoesters on 11 sorts of main human UGT isoforms. 100 μM phthalate monoesters exhibited negligible inhibition towards the activity of UGT1A1, UGT1A3, UGT1A6, UGT1A8, UGT1A10, UGT2B4, UGT2B7, UGT2B15 and UGT2B17. The activity of UGT1A7 was strongly inhibited by monoethylhexyl phthalate (MEHP), but slightly inhibited by all the other phthalate monoesters. UGT1A9 was broadly inhibited by monobenzyl phthalate (MBZP), monocyclohexyl phthalate (MCHP), MEHP, monohexyl phthalate (MHP) and monooctyl phthalate (MOP), respectively. MEHP exhibited competitive inhibition towards UGT1A7, and MBZP, MCHP, MEHP, MHP and MOP showed competitive inhibition towards UGT1A9. The inhibition kinetic parameters (Ki) were calculated to be 11.25 μM for MEHP-UGT1A7, and 2.13, 0.09, 1.17, 7.47, 0.16 μM for MBZP-UGT1A9, MCHP-UGT1A9, MEHP-UGT1A9, MHP-UGT1A9, MOP-UGT1A9, respectively. Molecular docking indicated that both hydrogen bonds formation and hydrophobic interactions significantly contributed to the interaction between phthalate monoesters and UGT isoforms. All these information will be beneficial for understanding the adverse effects of PAEs.

Analytical method for urinary metabolites as biomarkers for monitoring exposure to phthalates by gas chromatography/mass spectrometry.

Phthalates, widely used as plasticizers, have been detected in indoor air, but there have been few reports on methods of analyzing urinary metabolites as biomarkers to monitor exposure to di-n-pentyl phthalate or di-n-hexyl phthalate. Presented here is a cost-effective and sensitive analytical method for the determination of urinary metabolites of phthalates containing these two compounds. Nine urinary phthalate metabolites were enzymatically hydrolyzed and extracted with toluene: monomethyl phthalate, monoethyl phthalate, monoisobutyl phthalate, mono-n-butyl phthalate, mono-n-pentyl phthalate, mono-n-hexyl phthalate, monocyclohexyl phthalate, monobenzyl phthalate and mono(2-ethyl-5-carboxypentyl) phthalate. After transformation to their tert-butyldimethylsilyl derivatives, they were analyzed by gas chromatography/mass spectrometry in the electron impact ionization mode. The calibration curves for the metabolites were linear at urinary concentrations of up to 30 μg/L, showing that they could be determined accurately and precisely (detection limits 0.1-0.4 μg/L, quantification limits 0.3-1.3 μg/L). The urine samples collected could be stored for up to 1 month at -20°C. The proposed analytical method was used to examine urine samples from seven healthy volunteers. This method should be useful for monitoring phthalate exposure in the general population.