DEHP Metabolites Research Articles

Dimethyl Fumarate Attenuates Di-(2-Ethylhexyl) Phthalate-Induced Nephrotoxicity Through the Nrf2/HO-1 and NF-κB Signaling Pathways.

This study aimed to clarify the nephroprotective effect of dimethyl fumarate (DMF) against Di (2-ethylhexyl) phthalate (DEHP)-induced nephrotoxicity in both in vitro and in vivo models. The HEK-293 cells were exposed to different concentrations of DMF plus IC50 concentration of monoethylhexyl phthalate (MEHP) (the main metabolite of DEHP). Then, some of the oxidative stress parameters including ROS, MDA, and GSH, and cytotoxicity (MTT assay) were determined in treated cells. For in vivo evaluation, rats were divided into 7 groups (n = 6 per group). Corn oil group (gavage), DEHP group (200mg/kg dissolved in corn oil, gavage), DMF (15, 30, and 60mg/kg, gavage) plus DEHP (200mg/kg) groups, DMF (60mg/kg, gavage) alone, and vitamin E (20mg/kg, intraperitoneal (IP)) plus DEHP (200mg/kg) group. This treatment continued for 45days. Then, BUN and creatinine were evaluated by a commercial kit based on the urease enzymatic method and the Jaffe method, respectively. Mitochondrial oxidative stress and mitochondrial dysfunction parameters were evaluated using appropriate reagents, and gene expression of the p65 nuclear factor kappa B (NF-κB), tumor necrosis factor alpha (TNFα), nuclear factor E2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) were evaluated by real-time PCR method. High concentrations of DMF significantly increased cell viability, and GSH content and significantly decreased ROS and MDA levels compared with the MEHP group in HEK-293 cells. DMF (60mg/kg) significantly decreased BUN and creatinine levels compared with the DEHP group. Mitochondrial function and mitochondrial swelling were significantly improved in DMF group (60mg/kg) compared with the DEHP group. DMF (30 and 60mg/kg) significantly improved MMP collapse compared with the DEHP group. DMF (30 and 60mg/kg) significantly decreased ROS levels compared with the DEHP group in isolated kidney mitochondria. DMF (60mg/kg) significantly decreased MDA levels and significantly increased GSH content compared with DEHP group in isolated kidney mitochondria. The mRNA expression levels of Nrf2 and HO-1 were significantly reduced in the DEHP group compared to the control group and were significantly increased in the DMF group compared to the DEHP group. p65NF-κB and TNFα mRNA expression levels were significantly increased in the DEHP group compared to the control group. However, DMF significantly decreased p65NF-κB and TNFα mRNA expression compared to the DEHP group. DMF can act as a nephroprotective agent against DEHP partly through modulation of oxidative stress, mitochondrial function, and inflammation.

Association between chemical mixtures and female fertility in women undergoing assisted reproduction in Sweden and Estonia

ObjectiveWomen of reproductive age are exposed to ubiquitous chemicals such as phthalates, parabens, and per- and polyfluoroalkyl substances (PFAS), which have potential endocrine disrupting properties and might affect fertility. Our objective was to investigate associations between potential endocrine-disrupting chemicals (EDCs) and female fertility in two cohorts of women attending fertility clinics. MethodsIn a total population of 333 women in Sweden and Estonia, we studied the associations between chemicals and female fertility, evaluating ovarian sensitivity index (OSI) as an indicator of ovarian response, as well as clinical pregnancy and live birth from fresh and frozen embryo transfers. We measured 59 chemicals in follicular fluid samples and detected 3 phthalate metabolites, di-2-ethylhexyl phthalate (DEHP) metabolites, 1 paraben, and 6 PFAS in >90% of the women. Associations were evaluated using multivariable-adjusted linear or logistic regression, categorizing EDCs into quartiles of their distributions, as well as with Bayesian Kernel Machine Regression. ResultsWe observed statistically significant lower OSI at higher concentrations of the sum of DEHP metabolites in the Swedish cohort (Q4 vs Q1, β = -0.21, 95% CI: −0.38, −0.05) and methylparaben in the Estonian cohort (Q3 vs Q1, β = -0.22, 95% CI: −0.44, −0.01). Signals of potential associations were also observed at higher concentrations of PFUnDA in both the combined population (Q2 vs. Q1, β = −0.16, 95% CI -0.31, −0.02) and the Estonian population (Q2 vs. Q1, β = −0.27, 95% CI -0.45, −0.08), and for PFOA in the Estonian population (Q4 vs. Q1, β = −0.31, 95% CI -0.61, −0.01). Associations of chemicals with clinical pregnancy and live birth presented wide confidence intervals. ConclusionsWithin a large chemical mixture, we observed significant inverse associations levels of DEHP metabolites and methylparaben, and possibly PFUnDA and PFOA, with OSI, suggesting that these chemicals may contribute to altered ovarian function and infertility in women.

Dose–response mapping of MEHP exposure with metabolic changes of trophoblast cell and determination of sensitive markers

Mono(2-ethylhexyl) phthalate (MEHP) is a metabolite of DEHP which is one of phthalic acid esters (PAEs) widely used in daily necessities. Moreover, MEHP has been proven to have stronger biological toxicity comparing to DEHP. In particular, several recent population-based studies have reported that intrauterine exposure to MEHP results in adverse pregnancy outcomes. To explore the mechanisms and metabolic biomarkers of MEHP exposure, we examined the metabolic status of HTR-8/Svneo cell lines exposed to different doses of MEHP (0, 1.25, 5.0, 20 μM). Global and dose–response metabolomics tools were used to identify metabolic perturbations and sensitive markers associated with MEHP. Only 22 metabolic features (accounted for <1 %) were significantly changed when exposed to 1.25 μM. However, when the exposure dose was increased to 5 or 20 μM, the number of significantly changed metabolic features exceeded 300 (approximately 10 %). In particular, amino acid metabolism, pyrimidine metabolism and glutathione metabolism were widely affected according to the enrich analysis of those significant altered metabolites, which has and have previously been reported to be closely related to fetal development. Moreover, 5′-UMP and N-acetylputrescine with the lowest effective concentrations (EC−10 = 0.1 μM and EC+10 = 0.11 μM, respectively) were identified as sensitive endogenous biomarkers of MEHP exposure.

Urinary phthalate metabolites and phenolics in women of childbearing age and their association with thyroid hormones: a comparison study of fasting status

[BACKGROUND AND AIM] Exposure to parabens and phthalates has been associated with thyroid hormones in humans. Epidemiologic observations, however, are often inconsistent depending on population, probably due to different susceptibility or other factors such as exposure misclassification. Fasting status may influence the urinary levels of many chemicals, especially when their major exposure pathways are related to diet. In the present study, we assessed the associations of urinary phthalate metabolites and phenolics with thyroid hormones in non-pregnant women of child-bearing age in Korea (20-49 years of age), considering fasting status. [METHODS] As a fasting population, we recruited women (n=254) who visited four hospitals after &amp;#x3e;9 hr of fasting between 2015 and 2016. From the fasting women, we measured phthalate metabolites and parabens in urine, and thyroid hormones in serum. Non-pregnant women of the same age group, who were not asked to fast, was chosen from KoNEHS Cycle 3 (2015-2017) (phthalate metabolites (n=341) and phenolics (n=340)). [RESULTS] Urinary concentrations of MEHHP, MEOHP, MBzP, and BPA were &amp;#x3e;2 folds higher in the non-fasting women, and those of MeP were higher in the fasting women. Regardless of fasting status, MeP and EtP levels showed significant negative association with both total and free T4. DEHP metabolites also showed negative associations with free T4 but positive associations with total T3. However, associations of MBzP and BPA with thyroid hormones varied by the fasting status, which might be due to the influence of diet on their urinary concentrations. [CONCLUSION] While certain chemicals like EtP and to lesser extent DEHP are known to be delivered through dietary factors, consistent associations with altered thyroid hormones regardless of fasting status are noteworthy. [KEYWORDS] thyroid hormones; fasting; phthalates; phenolics [Acknowledgement] This work was supported by grants from National Research Foundation of Korea (NRF) (NRF-2020R1A2C3011269 and NRF-2022R1C1C2006982).

Benchmark dose in the presence of coexposure to melamine and diethylhexyl phthalate and urinary renal injury markers in pregnant women

Environmental exposures to mixtures of toxic chemicals have potential interaction effects that may lead to hazard index values exceeding one. However, current regulation levels, such as tolerable daily intake (TDI), are mostly based on experimental studies conducted with a single chemical compound. In this study, we assessed the relationships between melamine and di-(2-ethylhexyl) phthalate (DEHP) exposure and their coexposure with the early renal injury markers N-acetyl -D-glucosaminidase (NAG), albumin/creatinine ratio (ACR), and microalbuminuria in 1236 pregnant women. Various generalized linear models with interaction terms and Bayesian kernel machine regression models were used for the (co-)exposure response associations. We derived the benchmark dose (BMD) and the corresponding one-sided 95% confidence bound BMDL based on the estimated (covariate-adjusted) average daily intake of melamine and DEHP metabolites measured in spot urine of the women collected during the third trimester. Given a benchmark response of 0.1, the BMDL level of melamine (DEHP) exposure on NAG (ACR, microalbuminuria) was 2.67 (11.20, 4.45) μg/kg_bw/day, and it decreased to as low as 1.46 (3.83, 2.73) μg/kg_bw/day when considering coexposure to DEHP (melamine) up to the 90th percentile. Both the exposure threshold levels of melamine and DEHP for early renal injuries in pregnant women were several-fold to one order lower than the current recommended TDIs by the WHO and the US FDA and EPA and were even lower considering coexposure. Because of concurrent exposures in real-world environments, more stringent regulation levels are recommended in susceptible populations, such as pregnant women, due to potential synergistic mixture effects.

Di(2-ethylhexyl) phthalate induced thyroid toxicity via endoplasmic reticulum stress: In vivo and in vitro study.

Di(2-ethylhexyl) phthalate (DEHP) could induce thyroid injury but the mechanism was unclear. This study combined in vivo and in vitro experiments to clarify the mechanism. In vivo, the offspring of Sprague Dawley rats were gavaged with different doses of DEHP (5, 50, and 250 mg/[kg⋅d]) from in utero to 12 weeks-old. Transcriptome sequencing was used to detect the mRNA expression profile of the offspring's thyroids. Differentially expressed genes were identified, followed by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. In vitro, Nthy-ori 3-1 cells were exposed to DEHP's metabolite mono (2-ethylhexyl) phthalate (MEHP) to verify the pathway we found by KEGG analysis. The results indicated that DEHP could disorder the thyroid hormones. Compared with the offspring in control group, the mRNA levels of 656 genes were upregulated in the offspring exposed to 50 mg/(kg⋅d) DEHP. The upregulated genes were enriched in the pathway of "protein processing in the endoplasmic reticulum (ER)." It indicated that the ER stress might play significant role in the thyroid toxicity induced by DEHP. In vitro, the mitochondrial membrane potential (ΔΨm) level of cells was decreased while the reactive oxygen species level was increased after MEHP exposure. MEHP increased the intracellular Ca2+ level and induced ER stress. After ER stress was inhibited by the 4-phenylbutyric acid, the thyroid toxicity caused by MEHP was alleviated. Taken together, our results indicated that DEHP could induce thyroid toxicity by activating ER stress.

The relationship between exposure to phthalate metabolites and adult-onset hypogonadism.

ObjectiveAdult-onset hypogonadism (AOH) is a common disease for males >40 years old and is closely associated with age-related comorbidities. Phthalates are compounds widely used in a number of products with endocrine-disrupting effects. However, little is known about the association between exposure to phthalates and the risk of AOH. Thus, we conducted this study to explore the potential association using the 2013-2016 National Health and Nutrition Examination Survey (NHANES) data.MethodData on AOH and urinary phthalate metabolites were collected, and univariable and multivariable logistic regression analyses were adapted to evaluate the association. The concentrations of each metabolite were calculated and grouped according to their quartiles for the final analysis.ResultFinally, we found that the odds ratio (OR) increased with increased concentrations of di-(2-ethylhexyl) phthalate (DEHP) metabolites, including mono(2-ethyl-5-carboxypentyl) phthalate (MECPP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP). Simultaneously, a significant dose-dependent effect was also observed. The OR for the fourth quartile was highest among all three groups. Specifically, the ORs for the third quartile and fourth quartile were 1.774 and 1.858, respectively, in the MECPP group. For the MEHHP group, the OR increased from 1.580 for the second quartile to 1.814 for the fourth quartile. Similarly, the OR for the higher three quartiles varied from 1.424 to 1.715 in the MEOHP group.ConclusionThis study first revealed that there was a positive association between exposure to DEHP metabolites and the risk of AOH. These findings add limited evidence to study this topic, while further studies are needed to explain the potential molecular mechanisms.

Long-term stability of several endocrine disruptors in the first morning urine samples and their associations with lifestyle characteristics

Parabens, triclosan (TCS), bisphenols, benzophenones, and phthalates are typical endocrine disruptors (EDs) with short half-lives in the human body. The concentration levels of those EDs in a spot urine sample are frequently used in exposure assessment studies, and the reproducibility of urinary levels of these nonpersistent EDs should be considered. In the present study, we consecutively collected 45-day first morning void (FMV) urine samples, as well as daily questionnaires, in six recruited participants and measured the urinary concentrations of six parabens, TCS, nine bisphenols, five benzophenones, and ten phthalate metabolites by using high-performance liquid chromatography-tandem mass spectrometry. MeP, EtP, PrP, TCS, BPA, BPS, BPF, and most phthalate metabolites were frequently detected (over 62 % of samples). The intraclass correlation coefficients (ICCs) for ED concentrations in FMV urine samples ranged from fair to excellent for MeP (0.683), EtP (0.702), BPA (0.505), BPS (0.908), BPF (0.887), BP-3 (0.712), mMP (0.661), mEP (0.523), mBP (0.500), miBP (0.724), mBzP (0.961) and all metabolites of DEHP (0.867–0.957), whereas they were low for PrP (0.321) and TCS (0.306). After creatinine adjustment, the values of ICCs for most target EDs were increased with mild to significant improvement. The stability of ED concentrations was affected by daily diet (MeP, TCS, BPA, mMP, miBP, mBP and mBzP), food containers (PrP and mECPP), use of personal care products (HMWP metabolites), pharmaceuticals (EtP) and recorded activities (BPS, mEHP, mBzP, mEHHP and mEOHP), as confirmed by a general linear mixed model. Furthermore, extending the FMV sampling period improved the probability of acceptable reproducibility (ICCs > 0.40) of MeP, EtP, BP-3 and mEP concentrations. For BPS, BPF and HMWP metabolite concentrations showed high probabilities (>80 %) of acceptable reproducibility in the last three days, and the increasing sample size slowly improved the ability to discriminate the subjects. The results were exactly the opposite for BPA concentrations.

The associations between prenatal phthalate exposure measured in child meconium and cognitive functioning of 12-month-old children in two cohorts at elevated risk for adverse neurodevelopment

BackgroundPhthalate metabolites in gestational-maternal urine represents short-term maternal exposure, but meconium, the newborn's first stool may better capture cumulative fetal exposure. We quantified phthalate metabolites in meconium from two cohorts of children at higher risk of adverse neurodevelopment and evaluated associations with their cognitive function at 12 months. MethodsMeconium phthalate metabolites were quantified in the Safe Passage Study (SPS), N = 720, a pregnancy cohort with high community-levels of prenatal alcohol use, and the Early Autism Risk Longitudinal Investigation (EARLI), N = 236, a high familial autism risk pregnancy cohort. EARLI also had second and third trimester (T2/T3) maternal urine for exposure assessment. Molar sum of di (2-ethylhexyl) (∑DEHP) metabolites and an anti-androgenic score (AAS) using mono-isobutyl, mono-n-butyl, monobenzyl (MBZP), and DEHP metabolites were computed. Cognitive function was assessed at 12 months using the Mullen Scales of Early Learning-Composite (ELC). Multivariable linear regression assessed associations between loge-transformed metabolites and ELC. Quadratic terms explored nonlinearity and interaction terms of metabolite by child's sex examined effect modification. ResultsIn SPS, MBzP (βLinear = −6.73; 95% CI: 12.04, −1.42; βquadratic = 1.95; 0.27, 3.62) and mono (2-ethyl-5-carboxypentyl), (βLinear = −3.81; −7.53, −0.27; βquadratic = 0.93; 0.09, 1.77) had U-shaped associations with ELC. In EARLI, T2 urine mono-carboxyisononyl was associated with linear decrease in ELC, indicating lower cognitive function. Interaction with sex was suggested (P < 0.2) for several urine metabolites, mostly indicating negative association between phthalates and ELC among girls but reversed among boys. Only mono-isononyl phthalate and ∑DEHP had consistent main effect associations across matrixes and cohorts, but similar interaction with sex was observed for meconium-measured ∑DEHP, AAS, MBzP, and mono (2-ethylhexyl) in both cohorts. ConclusionsFew phthalate metabolites were consistently associated with children's cognitive function, but a similar set of meconium metabolites from both cohorts displayed sex-specific associations. Gestational phthalate exposure may have sexually-dimorphic associations with early cognitive function in children at higher risk for adverse neurodevelopment.

Urinary metabolites and handwipe phthalate levels among adults and children in southern China: Implication for dermal exposure

Paired handwipe and urine samples were collected from adult (n = 130) and child (n = 82) residents of a typical urban community in southern China to examine relationships between external and internal exposure as well as the contribution of dermal absorption to the exposure of phthalates. The concentrations and composition profiles of phthalates were similar in handwipes from both adults and children, and contained mainly di-2-ethylhexyl phthalate (DEHP), di-n-butyl phthalate (DnBP) and di-iso-butyl phthalate (DiBP), consistent with profiles of phthalates in air and dust. The major metabolites of these phthalates, i.e., mono-n-butyl phthalate (mnBP) from DnBP, mono-iso-butyl phthalate (miBP) from DiBP and three metabolites of DEHP (namely mEHP, mEHHP and mEOHP) were widely detected in paired urine samples. Positive correlations were found between contamination levels of DiBP and DnBP in handwipes and their corresponding urinary metabolites, whereas no significant correlation was observed for DEHP. This suggests that dermal absorption might be an important exposure pathway particularly for low molecular weight phthalates. Our study shows that dermal absorption is a non-negligible exposure pathway for phthalates, to which children are particularly sensitive since the contribution of dermal uptake to the internal exposure of phthalates was higher in children than adults.

Di-(2-ethylhexyl) phthalate exposure links to inflammation and low bone mass in premenopausal and postmenopausal females: Evidence from ovariectomized mice and humans.

Phthalates induce inflammation and are ubiquitously used in daily life. We aim to study the impact of di-(2-ethylhexyl) phthalate (DEHP) exposure on inflammation and osteoporosis in premenopausal and postmenopausal females. Female 8-week-old C57BL/6JNarl mice received an ovariectomy (OVX) or a sham operation and were fed with DEHP or vehicle by oral gavage for 4 or 8 weeks. Their femurs were isolated for micro-computed tomography, and their serum was collected for inflammatory cytokine assays. Correlations between urinary phthalate metabolites and the lumbar spine bone mineral density (BMD) in premenopausal and postmenopausal volunteers were performed. Among the OVX mice treated for 4 weeks, significant lower bone volume, bone volume/tissue volume, and trabecular number but significant higher trabecular bone pattern factor and structure model index were identified in the mice treated with DEHP than with vehicle. The OVX mice treated with DEHP for 4 weeks had significantly higher serum interleukin (IL)-1β, IL-10, IL-17A, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and Dickkopf-1 levels than those treated with vehicle. The sham mice treated with DEHP for 8 weeks showed an impaired femur trabecular microstructure and had significantly higher serum IL-1β, IL-6, IL-10, IL-17A, IFN-γ, and TNF-α than those treated with vehicle. DEHP metabolites were inversely correlated with the BMD of premenopausal women and the T-score of postmenopausal women. DEHP treatment in OVX and sham mice results in osteoporosis and impairs the microstructure of the femur trabecula through inflammation. Phthalate exposure negatively affects the bone mass in both premenopausal and postmenopausal women. Thus, long-term avoidance is suggested.

Analysis of the performance of the efficient di-(2-ethylhexyl) phthalate-degrading bacterium Rhodococcus pyridinovorans DNHP-S2 and associated catabolic pathways

The widespread use of plastic has led to the global occurrence of phthalate esters (PAEs) pollution. PAEs can be effectively removed from polluted environments by microbe-mediated degradation. Di-(2-ethylhexyl) phthalate (DEHP) has the highest residual concentration in agricultural soil-contaminated areas compared to other PAEs in most of China. The Rhodococcus pyridinovorans DNHP-S2 microbial isolate identified was found to efficiently degrade DEHP. Within a 72 h period, the bacteria were able to degrade 52.47% and 99.75% of 500 mg L−1 DEHP at 10 °C and 35 °C, respectively. Dimethyl phthalate (DMP) was first identified as an intermediate metabolite of DEHP, which is different from the previously reported DEHP catabolic pathway. Genomic sequencing of DNHP-S2 identified benzoate 1,2-dioxygenase and catechol 2,3/1,2-dioxygenase as potential mediators of DEHP degradation, consistent with the existence of two downstream metabolic pathways governing DEHP degradation. Three targets DEHP metabolism-related enzymes were found to be DEHP-inducible at the mRNA level, and DNHP-S2 was able to mediate the complete degradation of DEHP at lower temperatures, as confirmed via RT-qPCR. DNHP-S2 was also found to readily break down other PAEs including DMP, di-n-butyl phthalate (DBP), di-n-octyl phthalate (DnOP), and n-butyl benzyl phthalate (BBP). Together, these results thus highlight DNHP-S2 as a bacterial strain with great promise as a tool for the remediation of PAE pollution. In addition to providing new germplasm and genetic resources for use in the context of PAE degradation, these results also offer new insight into the potential mechanisms whereby PAEs undergo catabolic degradation, making them well-suited for use in PAE-contaminated environments.

Prenatal single and combined exposure to phthalates associated with girls’ BMI trajectory in the first six years

Evidence of the influence of prenatal phthalate exposure on childhood longitudinal obesity markers is limited. Nested on the Ma’anshan birth cohort study, 990 mother-daughter pairs were included. Seven phthalate metabolites were determined in urine collected in each trimester. Each child underwent a physical examination from birth to 6 years of age twelve times. Latent class growth models were used to identify three trajectories of girls’ body mass index (BMI). Logistic regression, quantile g-computation and Bayesian kernel machine regression models analyzed the relationships of prenatal exposure to individual and mixed phthalates with girls’ body mass index (BMI) trajectory. Compared to the “lowest trajectory” class, prenatal average concentrations of mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP, ORcrude = 2.095, 95 % CI = 1.014–4.328) and di(2-ethylhexyl) phthalate (DEHP, ORcrude = 2.336, 95 % CI = 1.022–5.338) during pregnancy were associated with an increased probability of being in the “highest trajectory” class. The average concentration of DEHP (ORcrude = 1.879, 95 % CI = 1.002–3.522) was associated with an increased probability of being in the “moderate trajectory” class. Stratified analyses by trimester of pregnancy mainly showed that third-trimester exposure to monoethyl phthalate (MEP, ORadjusted = 1.584, 95 % CI = 1.094–2.292), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP, ORadjusted = 2.885, 95 % CI = 1.367–6.088), MEHHP (ORadjusted = 2.425, 95 % CI = 1.335–4.407), DEHP (ORadjusted = 2.632, 95 % CI = 1.334–5.193) and high molecular weight phthalate (ORadjusted = 2.437, 95 % CI = 1.239–4.792) was associated with an increased probability of being in the “highest trajectory” class. However, the mixture of phthalates was not significantly related to the girl’s BMI trajectory. In conclusion, in utero exposure to phthalates, including MEP and DEHP metabolites (MEHHP and MEOHP), was significantly associated with early childhood high BMI trajectories in girls. The third trimester of pregnancy seemed to be the window of vulnerability to phthalate exposure for girls’ high BMI trajectory at periods of prenatal development. No evidence supported a significant relationship between combined exposure to phthalate metabolites and girls’ high BMI trajectory.

Urine Di-(2-ethylhexyl) Phthalate Metabolites Are Independently Related to Body Fluid Status in Adults: Results from a U.S. Nationally Representative Survey

Purpose: Di-(2-ethylhexyl) phthalate (DEHP) has been utilized in many daily products for decades. Previous studies have reported that DEHP exposure could induce renin–angiotensin–aldosterone system activation and increase epithelial sodium channel (ENaC) activity, which contributes to extracellular fluid (ECF) volume expansion. However, there is also no previous study to evaluate the association between DEHP exposure and body fluid status. Methods: We selected 1678 subjects (aged ≥18 years) from a National Health and Nutrition Examination Survey (NHANES) in 2003–2004 to determine the relationship between urine DEHP metabolites and body composition (body measures, bioelectrical impedance analysis (BIA)). Results: After weighing the sampling strategy in multiple linear regression analysis, we report that higher levels of DEHP metabolites are correlated with increases in body measures (body weight, body mass index (BMI), waist circumference), BIA parameters (estimated fat mass, percent body fat, ECF, and ECF/intracellular fluid (ICF) ratio) in multiple linear regression analysis. The relationship between DEHP metabolites and the ECF/ICF ratio was more evident in subjects of younger age (20–39 years old), women, non-Hispanic white ethnicity, and subjects who were not active smokers. Conclusion: In addition to being positively correlated with body measures and body fat, we found that urine DEHP metabolites were positively correlated with ECF and the ECF/ICF ratio in the US general adult population. The finding implies that DEHP exposures might increase ECF volume and the ECF/ICF ratio, which may have adverse health outcomes on the cardiovascular system. Further research is needed to clarify the causal relationship.

Urinary phthalate metabolite concentrations during four windows spanning puberty (prepuberty through sexual maturity) and association with semen quality among young Russian men.

To prospectively investigate the associations of urinary phthalate metabolite concentrations measured at four time points spanning pubertal development with semen parameters in Russian men. 516 boys were enrolled at ages 8-9 years (2003-2005) and followed annually. Urine samples were collected annually and pooled into four exposure windows [prepuberty, early puberty, late puberty and sexual maturity] based on physician assessed Tanner genitalia stages and testicular volume. Fifteen phthalate metabolites were quantified using isotope dilution HPLC-MS/MS at Moscow State University. We calculated molar sums (∑) of di-2-ethylhexyl phthalate (DEHP), di-isononyl phthalate (DiNP), di-isodecyl phthalate (DiDP) and anti-androgenic phthalate (AAP) metabolites. At sexual maturity (ages 18-19 years), the men provided 1-2 semen samples for analysis. We estimated the associations of quintiles of urinary ∑phthalate metabolites as well as mono-butyl phthalate (MnBP), mono-isobutyl phthalate (MiBP), and mono-benzyl phthalate (MBzP) at each pubertal window, with semen parameters by fitting generalized linear mixed models with random intercepts and adjusting for confounders. A total of 223 men who provided semen samples had phthalates measured at one or more pubertal windows. Higher urinary concentrations of ∑DiNP metabolites during late puberty were related to poorer semen quality (men with the highest quintile of urinary ∑DiNP had 30% lower sperm concentration, 32% lower count and 30% lower progressive motile count, compared to men in the lowest quintile). Also, young men with higher urinary concentrations of MiBP metabolites in early puberty tended to have poorer semen quality. No associations were observed for ∑DEHP metabolites, ∑DiDP metabolites, ∑AAP, MBzP or MnBP metabolites with semen quality parameters. ∑DiNP metabolites measured during late puberty and MiBP metabolites at early puberty were related to poorer semen quality, highlighting the importance of considering specific windows of exposure when investigating chemical exposures in relation to measures of reproductive health in men.

Associations of environmental phthalate exposure with male steroid hormone synthesis and metabolism: An integrated epidemiology and toxicology study

Humans are simultaneously and constantly exposed to various lipophilic chain phthalate acid esters. The association of urinary phthalate metabolites with altered male steroid hormone synthesis and metabolism was examined using epidemiology and toxicology studies. We measured 8 phthalate metabolites [monomethyl phthalate (MMP), monoethyl phthalate (MEP), mono-n-butyl phthalate (MBP), mono-benzyl phthalate (MBzP), mono-n-octylphthalate (MOP), mono-(2-ethylhexyl) phthalate (MEHP), mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono (2-ethyl-5-oxohexyl) phthalate (MEOHP)] and two sex hormones [testosterone (T) and estradiol (E2)] in single serum and repeated spot urine samples among 451 reproductive-age males. Moreover, in vitro experiments with Leydig cell MLTC-1 steroidogenesis and liver cell HepG2 efflux in response to mixed and individual phthalates were designed to simulate real-world scenarios of human exposure. As a joint mixture, the phthalate metabolite was inversely associated with serum T and E2 concentrations but positively associated with urinary T and E2 concentrations. Combined with in vitro experiments, DEHP metabolites were identified as the predominant contributor to the decline in hormone synthesis, and ATP-binding cassette (ABC) gene activation might be involved in hormone excretion. Exposure to environmentally relevant phthalates was associated with both altered steroid synthesis and excretion, which provides additional insights into the endocrine-disrupting potential of phthalates.

Di-(2-ethylhexyl) Phthalate Promotes Allergic Lung Inflammation by Modulating CD8α+ Dendritic Cell Differentiation via Metabolite MEHP-PPARγ Axis.

Di-(2-ethylhexyl) phthalate (DEHP), a common plasticizer, is a ubiquitous environmental pollutant that can disrupt endocrine function. Epidemiological studies suggest that chronic exposure to DEHP in the environment is associated with the prevalence of childhood allergic diseases; however, the underlying causal relationship and immunological mechanism remain unclear. This study explored the immunomodulatory effect of DEHP on allergic lung inflammation, while particularly focusing on the impact of DEHP and its metabolite on dendritic cell differentiation and activity of peroxisome proliferator-activated receptor gamma (PPARγ). The results showed that exposure to DEHP at a human tolerable daily intake dose exacerbated allergic lung inflammation in mice. Ex vivo flow cytometric analysis revealed that DEHP-exposed mice displayed a significantly decreased number of CD8α+ dendritic cells (DCs) in spleens and DC progenitors in the bone marrow, as well as, less interleukin-12 production in splenic DCs and increased T helper 2 polarization. Pharmacological experiments showed that mono-(2-ethylhexyl) phthalate (MEHP), the main metabolite of DEHP, significantly hampered the differentiation of CD8α+ DCs from Fms-like tyrosine kinase 3 ligand-differentiated bone marrow culture, by modulating PPARγ activity. These results suggested that chronic exposure to DEHP at environmentally relevant levels, promotes allergic lung inflammation, at least in part, by altering DC differentiation through the MEHP-PPARγ axis. This study has crucial implications for the interaction(s) between environmental pollutants and innate immunity, with respect to the development of allergic asthma.

Time-trends in human urinary concentrations of phthalates and substitutes DEHT and DINCH in Asian and North American countries (2009–2019)

BackgroundMany phthalates are environmental pollutants and toxic to humans. Following phthalate regulations, human exposure to phthalates has globally decreased with time in European countries, the US and Korea. Conversely, exposure to their substitutes DEHT and/or DINCH has increased. In other countries, including China, little is known on the time-trends in human exposure to these plasticizers.ObjectiveWe aimed to estimate time-trends in the urinary concentrations of phthalates, DEHT, and DINCH metabolites, in general population from non-European countries, in the last decade.MethodsWe compiled human biomonitoring (HBM) data from 123 studies worldwide in a database termed “PhthaLit”. We analyzed time-trends in the urinary concentrations of the excreted metabolites of various phthalates as well as DEHT and DINCH per metabolite, age group, and country/region, in 2009–2019. Additionally, we compared urinary metabolites levels between continents.ResultsWe found solid time-trends in adults and/or children from the US, Canada, China and Taiwan. DEHP metabolites decreased in the US and Canada. Conversely in Asia, 5oxo- and 5OH-MEHP (DEHP metabolites) increased in Chinese children. For low-weight phthalates, the trends showed a mixed picture between metabolites and countries. Notably, MnBP (a DnBP metabolite) increased in China. The phthalate substitutes DEHT and DINCH markedly increased in the US.SignificanceWe addressed the major question of time-trends in human exposure to phthalates and their substitutes and compared the results in different countries worldwide.ImpactPhthalates account for more than 50% of the plasticizer world market. Because of their toxicity, some phthalates have been regulated. In turn, the consumption of non-phthalate substitutes, such as DEHT and DINCH, is growing. Currently, phthalates and their substitutes show high detection percentages in human urine. Concerning time-trends, several studies, mainly in Europe, show a global decrease in phthalate exposure, and an increase in the exposure to phthalate substitutes in the last decade. In this study, we address the important question of time-trends in human exposure to phthalates and their substitutes and compare the results in different countries worldwide.

Associations of Phthalate Metabolites and Bisphenol A Levels with Obesity in Children: The Korean National Environmental Health Survey (KoNEHS) 2015 to 2017.

BackgroundPhthalates and bisphenol A (BPA) are synthetic chemicals widely used in daily life. This study investigated urinary phthalate and BPA levels in Korean children and their associations with obesity. MethodsA total of 2,351 children aged 3 to 17 years who participated in the Korean National Environmental Health Survey 2015 to 2017 were included. Urinary dilution was corrected using covariate-adjusted standardization (CAS). We examined the geometric mean (GM) concentrations of urinary phthalate metabolites, including di (2-ethylhexyl) phthalate (DEHP) metabolites (mono [2-ethyl-5-hydroxyhexyl] phthalate, mono [2-ethyl-5-oxohexyl] phthalate, and mono [2-ethyl-5-carboxypentyl] phthalate [MECPP]), mono-benzyl-phthalate (MBzP), mono (carboxyoctyl) phthalate (MCOP), mono (carboxy-isononyl) phthalate (MCNP), mono (3-carboxypropyl) phthalate, and mono-n-butyl-phthalate (MnBP), and BPA. We also analyzed the odds ratio (OR) for obesity according to the quartiles of each analyte. ResultsThe urinary GM levels of DEHP metabolites and MnBP were notably higher among Korean children than among American, Canadian, and German children. The CAS-applied GM concentrations of most analytes, except for MBzP, MCOP, and MCNP, were higher in children aged 3 to 5 years than in those aged 6 to 17 years. The OR for obesity in the highest quartile of MECPP was significantly higher than in the lowest quartile after adjusting for covariates. However, the other phthalate metabolites and BPA were not significantly associated with obesity. ConclusionThe concentrations of urinary DEHP metabolites and MnBP were higher in Korean children than in children in Western countries. Urinary MECPP exposure, but not other phthalates or BPA, showed a positive association with obesity in Korean children. Further studies are required to elucidate the causal relationships.

Determinants of phthalate exposures in pregnant women in New York City

Previous studies have provided data on determinants of phthalates in pregnant women, but results were disparate across regions. We aimed to identify the food groups and demographic factors that predict phthalate exposure in an urban contemporary pregnancy cohort in the US. The study included 450 pregnant women from the New York University Children's Health and Environment Study in New York City. Urinary concentrations of 22 phthalate metabolites, including metabolites of di-2-ethylhexylphthalate (DEHP), were determined at three time points across pregnancy by liquid chromatography coupled with tandem mass spectrometry. The Diet History Questionnaire II was completed by pregnant women at mid-pregnancy to assess dietary information. Linear mixed models were fitted to examine determinants of urinary phthalate metabolite concentrations. Using partial-linear single-index (PLSI) models, we assessed the major contributors, among ten food groups, to phthalate exposure. Metabolites of DEHP and its ortho-phthalate replacement, diisononyl phthalate (DiNP), were found in >90% of the samples. The sum of creatinine-adjusted DiNP metabolite concentrations was higher in older and single women and in samples collected in summer. Hispanic and non-Hispanic Black women had lower urinary concentrations of summed metabolites of di-n-octyl phthalate (DnOP), but higher concentrations of low molecular weight phthalates compared with non-Hispanic White women. Each doubling of grain products consumed was associated with a 20.9% increase in ∑DiNP concentrations (95%CI: 4.5, 39.9). PLSI models revealed that intake of dried beans and peas was the main dietary factor contributing to urinary ∑DEHP, ∑DiNP, and ∑DnOP levels, with contribution proportions of 76.3%, 35.8%, and 27.4%, respectively. Urinary metabolite levels of phthalates in pregnant women in NYC varied by age, marital status, seasonality, race/ethnicity, and diet. These results lend insight into the major determinants of phthalates levels, and may be used to identify exposure sources and guide interventions to reduce exposures in susceptible populations.