Serum concentrations of phthalate metabolites in pregnant women and their association with gestational diabetes mellitus and blood glucose levels

Gestational Exposure to Endocrine-Disrupting Chemicals of Emerging Concern and the Risk of Developing Gestational Diabetes Mellitus: A Comprehensive Investigation of Sex-Specific and Trimester-Specific Associations

Gestational diabetes mellitus (GDM) is a type of diabetes that arises during pregnancy, leading to long-term adverse consequences for maternal health and fetal development. However, the specific role of endocrine-disrupting chemicals (EDCs) in the pathogenesis of GDM remains controversial. This prospective cohort study sought to investigate how coexposure to bisphenols, parabens, triclosan (TCS), benzophenone-type UV filters, and neonicotinoids (NEOs) affects the odds of GDM. Quantile-based g-computation and Bayesian kernel machine regression showed a significant inverse relationship between EDC mixtures and the reduced risk of GDM (OR = 0.34, 95% CI: 0.13-0.87), which was mainly explained by bisphenol (OR = 0.49, 95% CI: 0.29-0.80) and paraben (OR = 0.60, 95% CI: 0.40-0.91) exposure. Bisphenol S (BPS), bisphenol Z (BPZ), ethylparaben (EtP), propylparaben (PrP), and butylparaben (BuP) were identified as key contributors to the joint effect. In addition, subgroup analyses suggested that the bisphenols-GDM association was more pronounced in younger/normal-weight participants. The sex-specific impact of exposure to bisphenols on the development of GDM was observed, whereas the second trimester represented a critical window for EDC exposure. Continued research efforts, focusing on causal pathways and nonmonotonic relationships, will be crucial to elucidate the complex influence of EDC exposure on the development of GDM.

Phytotoxic impact of di-butyl phthalate (DBP) on physiological, biochemical, and oxidative stress parameters of rice (Oryza sativa)

Phthalates are synthetic compounds, well-known plasticizers, with numerous applications and reported to have adverse effects on all living organisms residing in terrestrial and aquatic environments. In this study, the rice (Oryza sativa) seedlings were exposed to di-butyl phthalate (DBP) exogenously for 7 days, with varying concentrations of 0, 200, 400, 800, and 1600 mg/L, to explore the toxicological, physiological, and biochemical consequences by measuring various parameters such as pigment, lipid, and H2O2 (hydrogen peroxide) contents. The biochemical analysis of seedlings showed that the pigments, lipids, and H2O2 concentrations were altered abnormally. After 7 days of exposure, the maximum amount of DBP was accumulated and translocated in both the shoot and root of the grown seedlings, and all morphological parameters (i.e., length and weight of both shoot and root) and pigment content (such as total carotenoid, chlorophyll a and b) were declined significantly. Superoxide dismutase (SOD), H2O2, and thiobarbituric acid reactive substance (TBARS) levels in seedlings increase as the stress increases due to the higher exposure dose of DBP. Cell viability was observed under a confocal microscope confirming the damage of the plasma membrane. Additionally, molecular docking studies indicated that DBP has a good binding affinity with key antioxidant enzymes of Oryza sativa, interacting via hydrogen bonds with specific amino acids. This suggests a potential mechanistic pathway for the observed biochemical changes in Oryza sativa.

Prenatal Exposure to Dibutyl Phthalate and Its Negative Health Effects on Offspring: In Vivo and Epidemiological Studies

Dibutyl phthalate (DBP) is a low-molecular-weight phthalate commonly found in personal care products, such as perfumes, aftershaves, and nail care items, as well as in children's toys, pharmaceuticals, and food products. It is used to improve flexibility, make polymer products soft and malleable, and as solvents and stabilizers in personal care products. Pregnancy represents a critical period during which both the mother and the developing embryo can be significantly impacted by exposure to endocrine disruptors. This article aims to elucidate the effects of prenatal exposure to DBP on the health and development of offspring, particularly on the reproductive, neurological, metabolic, renal, and digestive systems. Extensive research has examined the effects of DBP on the male reproductive system, where exposure is linked to decreased testosterone levels, reduced anogenital distance, and male infertility. In terms of the female reproductive system, DBP has been shown to elevate serum estradiol and progesterone levels, potentially compromising egg quality. Furthermore, exposure to this phthalate adversely affects neurodevelopment and is associated with obesity, metabolic disorders, and conditions such as hypospadias. These findings highlight how urgently stronger laws prohibiting the use of phthalates during pregnancy are needed to lower the risks to the fetus's health and the child's development.

Exploring diet as a source of plasticizers in pregnancy and implications for maternal second-trimester metabolic health

BACKGROUND AND OBJECTIVES

Diet plays critical roles in modulating maternal metabolic health in pregnancy, but is also a source of metabolic-disrupting phthalates and their replacements. We aimed to evaluate whether the effects of better diet quality on favorable maternal metabolic outcomes could be partially explained by lower exposure to phthalates/replacements.

METHODS

At 13 weeks gestation, 295 Illinois women (enrolled 2015-2018) completed a three-month food frequency questionnaire that we used to calculate the Alternative Healthy Eating Index (AHEI)-2010 to assess diet quality. We quantified 19 metabolites, reflecting exposure to 10 phthalates/replacements, in a pool of five first-morning urine samples collected monthly across pregnancy. We measured 15 metabolic biomarkers in fasting plasma samples collected at 17 weeks gestation, which we reduced to five uncorrelated principal components (PCs), representing adiposity, lipids, cholesterol, inflammation, and growth. We used linear regression to estimate associations of diet quality with [1] phthalates/replacements and [2] metabolic PCs, as well as [3] associations of phthalates/replacements with metabolic PCs. We estimated the proportion of associations between diet quality and metabolic outcomes explained by phthalates/replacements using a causal mediation framework.

RESULTS

Overall, every 10-point improvement in AHEI-2010 score was associated with -0.15 (95% CI: -0.27, -0.04) lower adiposity scores, reflecting lower glucose, insulin, C-peptide, leptin, C-reactive protein, but higher adiponectin biomarker levels. Every 10-point increase in diet quality was also associated with 18% (95%CI: 7%, 28%) lower sum of di-2-ethylhexyl terephthalate urinary metabolites (∑DEHTP). Correspondingly, each 18% increase in ∑DEHTP was associated with 0.03 point (95% CI: 0.01, 0.05) higher adiposity PC scores. In mediation analyses, 21% of the inverse relationship between diet quality and adiposity PC scores was explained by lower ∑DEHTP.

CONCLUSIONS

The favorable impact of diet quality on maternal adiposity biomarkers may be partially attributed to lower metabolite concentrations of DEHTP, a plasticizer allowed to be used in food packaging materials.

Thyroid hormones and oxidative stress moderated the association between urinary phthalate metabolites and cardiovascular risk factors

While previous studies suggested that phthalate exposure poses a risk to cardiovascular health, the results are mixed and indicated variability based on population characteristics and health outcomes assessed. Research that simultaneously investigates the association between urinary phthalate metabolites and multiple cardiovascular risk factors within a single study is relatively scarce. This study assessed human exposure to phthalates by determining urinary metabolite concentrations, and applied multiple statistical techniques to systematically evaluate the individual dose-response relationships and joint effects of phthalate exposure on blood lipids, blood pressure, and fasting blood glucose. The results revealed significant negative associations between urinary phthalate metabolites and low-density lipoprotein cholesterol, triglycerides, total cholesterol, diastolic blood pressure, systolic blood pressure, and fasting blood glucose. Significant nonlinear associations were obtained between specific individual metabolites and diastolic blood pressure. The oxidative stress biomarker 8-hydroxydeoxyguanosine levels in urine and thyroid hormone levels in paired serum were measured simultaneously. Then, we examined the indirect roles of thyroid hormones and oxidative stress in the association between urinary phthalate metabolites and cardiovascular risk factors by mediation and moderation analysis. While the mediation effect was not statistically significant, the negative associations of urinary phthalate metabolites with fasting blood glucose, triglyceride, and lipoprotein cholesterol were statistically significant at lower levels of thyroid hormones by moderation analysis. The association was also significant under certain levels of oxidative stress. The results demonstrated that phthalate exposure is associated with several cardiovascular risk factors, and maintaining appropriate oxidative stress levels and ensuring sufficient thyroid hormone levels may attenuate these associations.

Associations of urinary biomarkers of phthalates, phenols, parabens, and organophosphate esters with glycemic traits in pregnancy: The Healthy Start Study

BACKGROUND

Certain endocrine-disrupting chemicals (EDCs) are widespread in consumer products and may alter glucose metabolism. However, the impact of EDC exposures on glucose and insulin regulation during pregnancy is incompletely understood, despite potential adverse consequences for maternal and infant health. We estimated associations between 37 urinary biomarkers of EDCs and glucose-insulin traits among pregnant women.

METHODS

Seventeen phthalate or phthalate substitute metabolites, six environmental phenols, four parabens, and ten organophosphate ester metabolites were quantified in mid-pregnancy urine from 298 participants in the Healthy Start Study. Fasting blood glucose, insulin, and hemoglobin A1c were assessed concurrently, and Homeostasis Model Assessment 2-Insulin Resistance (HOMA2-IR) was calculated. Gestational diabetes diagnoses and screening results were obtained from medical records for a subset of participants. We estimated associations between each EDC and outcome separately using linear and robust Poisson regression models and analyzed EDC mixture effects.

RESULTS

The EDC mixture was positively associated with glucose, insulin, and HOMA2-IR, although overall associations were attenuated after adjustment for maternal BMI. Two mixture approaches identified di(2-ethylhexyl) phthalate (DEHP) metabolites as top contributors to the mixture's positive associations. In single-pollutant models, DEHP metabolites were positively associated with fasting glucose, fasting insulin, and HOMA2-IR even after adjustment for maternal BMI. For example, each interquartile range increase in log2-transformed mono(2-ethyl-5-oxohexyl) phthalate was associated with 2.4 mg/dL (95% confidence interval (CI): 1.1, 3.6) higher fasting glucose, 11.8% (95%CI: 3.6, 20.5) higher fasting insulin, and 12.3% (95%CI: 4.2, 21.1) higher HOMA2-IR. Few EDCs were associated with hemoglobin A1c or with a combined outcome of impaired glucose tolerance or gestational diabetes.

DISCUSSION

Exposures to phthalates and particularly DEHP during pregnancy are associated with altered glucose-insulin regulation. Disruptions in maternal glucose metabolism during pregnancy may contribute to adverse pregnancy outcomes including gestational diabetes and fetal macrosomia, and associated long-term consequences for maternal and child health.

Effect of prenatal phthalate exposure on fetal development and maternal/neonatal health consequences: A systematic review

The ubiquitous presence of phthalate compounds in cosmetics, personal care products and plastics commonly used in toys, food packaging or household products, results in human exposure with adverse effects on reproductive health and fetal development. Following the PRISMA methodology, this systematic review analyzes the effect of prenatal phthalate exposure on major pregnancy complications, such as gestational diabetes, pregnancy-induced hypertension, fetal growth restriction and preterm birth, and its role in fetal neurodevelopment. This review includes >100 articles published in the last 10 years, showing an association between maternal exposure to phthalates and the risk of developing pregnancy complications. Phthalates are negatively associated with motor skills and memory, and also increase the risk of delayed language acquisition, autism spectrum disorder traits, and behavioral deficits, such as attention deficit hyperactivity disorder in children prenatally exposed to phthalates. Di (2-ethylhexyl) phthalate and its metabolites (mono(2-ethylhexyl) phthalate, mono(3-carboxypropyl) phthalate, mono(2-ethyl-5-hydroxyhexyl) phthalate, mono(2-ethyl-5-oxohexyl) phthalate) are the main compounds associated with the above-mentioned pregnancy complications and fetal neurodevelopmental disorders. In addition, this review discusses the molecular mechanisms responsible for various pregnancy complications and neurodevelopmental disorders, and the critical window of exposure, in order to clarify these aspects. Globally, the most common molecular mechanisms involved in the effects of phthalates are endocrine disruption, oxidative stress induction, intrauterine inflammation, and DNA methylation disorders. In general, the critical window of exposure varies depending on the pathophysiology of the complication being studied, although the first trimester is considered an important period because some of the most vulnerable processes (embryogenesis and placentation) begin early in pregnancy. Future research should aim to understand the specific mechanism of the disruptive effect of each component and to establish the toxic dose of phthalates, as well as to elucidate the most critical period of pregnancy for exposure and the long-term consequences for human health.

Ca2+ homeostasis imbalance induced by Pparg: A key factor in di (2-ethylhexyl) phthalate (DEHP)-induced cardiac dysfunction in zebrafish larvae

Widespread application of the typical phthalate plasticizers, di (2-ethylhexyl) phthalate (DEHP), poses a serious potential threat to the health of animals and even humans. Previous studies have confirmed the mechanism of DEHP-induced cardiac developmental defects in zebrafish larvae. However, the mechanism of cardiac dysfunction is still unclear. Thus, this work aimed to comprehensively investigate the mechanisms involved in DEHP-induced cardiac dysfunction through computational simulations, in vivo assays in zebrafish, and in vitro assays in cardiomyocytes. Firstly, molecular docking and western blot initially investigated the activating effect of DEHP on Pparg in zebrafish. Although GW9662 (PPARG antagonist) effectively alleviated DEHP-induced cardiac dysfunction and lipid metabolism disorders, it did not restore significant decreases in mitochondrial membrane potential and ATP levels. In vitro assays in cardiomyocytes, DEHP caused overexpression of PPARG and proteins involved in the regulation of Ca2+ homeostasis, and the above abnormalities were effectively alleviated by GW9662, suggesting that the Ca2+ homeostatic imbalance caused by activation of PPARG by DEHP seems to be the main cause of DEHP-induced cardiac dysfunction. To sum up, this work not only refines the mechanism of toxic effects of cardiotoxicity induced by DEHP, but provides an important theoretical basis for enriching the toxicological effects of DEHP.

Crosstalk between aryl hydrocarbon receptor and Wnt/β-catenin signaling pathway: Possible culprit of di (2-ethylhexyl) phthalate-mediated cardiotoxicity in zebrafish larvae

Typical plasticizer di (2-ethylhexyl) phthalate (DEHP) has been demonstrated to induce cardiotoxicity in zebrafish, but the potential molecular mechanisms involved have not been fully elucidated. Aryl hydrocarbon receptor (AhR), an essential protein for inducing developmental abnormalities, has been demonstrated to be activated by DEHP in other species, but whether the AhR signaling pathway also contributes to DEHP-mediated cardiac developmental toxicity in zebrafish remains unclear. Firstly, molecular docking simulations initially confirmed the possibility that DEHP has AhR agonistic activity. To further confirm this conjecture, this work analyzed the changes of cardiac-related indexes in zebrafish stressed by DEHP at individual, protein, and gene levels. The results showed that DEHP mediated cardiac phenotypic developmental defects, increased CYP1A1 activity, and oxidative stress as well as significant changes in the expression levels of key proteins and genes of AhR, Wnt/β-catenin, and Nrf2-Keap1 signaling pathways. Notably, the addition of AhR inhibitors effectively alleviated the above negative effects, indicating that the AhR signaling pathway and its crosstalk with the Wnt/β-catenin signaling pathway is an essential pathway for DEHP-mediated cardiac developmental toxicity. Overall, this work enriches the molecular mechanism of DEHP-mediated cardiac developmental defects in zebrafish and provides a reliable biomarker for future environmental risk assessment of DEHP.

Endoplasmic reticulum stress and pro-inflammatory responses induced by phthalate metabolites monoethylhexyl phthalate and monobutyl phthalate in 1.1B4 pancreatic beta cells

In recent years, phthalates and their metabolites have been associated with metabolic diseases such as diabetes mellitus. To investigate the effects of phthalate metabolites exposure on insulin production and release, 1.1B4 pancreatic beta cells were treated with different concentrations (0.001-1000 µM) of monoethylhexyl phthalate (MEHP) and monobutyl phthalate (MBP). For such purpose, the 1.1B4 cells were evaluated for their viability, apoptosis rate, lysosomal membrane permeabilization (LMP), mitochondrial membrane potential (ΔΨm), oxidative stress, ER stress status, in addition to their secretory functions. MEHP, not MBP, exhibited a notable reduction in metabolic viability, particularly at higher concentrations (500 and 1000 µM) following 24-hour exposure. Similarly, both MEHP and MBP induced decreased metabolic viability at high concentrations after 48- and 72-hour exposure. Notably, neither MEHP nor MBP demonstrated a significant impact on apoptosis rates after 24-hour exposure, and MBP induced mild necrosis at 1000 µM concentration. Cell proliferation rates, indicated by PCNA expression, decreased with 10 and 1000 µM MEHP and 0.1 and 10 µM MBP exposures. LMP analysis revealed an increase in 1000 µM MBP group. Exposure to 0.001 µM of both MEHP and MBP significantly reduced cellular glutathione (GSH) levels. No significant change in intracellular reactive oxygen species (ROS) levels and ΔΨm was observed, but MBP-exposed cells exhibited elevated levels of lipid peroxidation. Functional assessments of pancreatic beta cells unveiled reduced insulin secretion at low glucose concentrations following exposure to both MEHP and MBP, with concurrent alterations in the expression levels of key proteins associated with beta cell function, including GLUT1, GCK, PDX1, and MafA. Moreover, MEHP and MBP exposures were associated with alterations in ER stress-related pathways, including JNK, GADD153, and NF-κB expression, as well as PPARα and PPARγ levels. In conclusion, this study provides comprehensive insights into the diverse impacts of MEHP and MBP on 1.1B4 pancreatic beta cells, emphasizing their potential role in modulating cell survival, metabolic function, and stress response pathways.

Phthalates (PAEs) and reproductive toxicity: Hypothalamic-pituitary-gonadal (HPG) axis aspects

Phthalates (PAEs) are widely used for their excellent ability to improve plastic products. As an essential endocrine axis that regulates the reproductive system, whether dysfunction of the hypothalamic-pituitary-gonadal (HPG) axis is involved in reproductive toxicity mediated by environmental endocrine disruptors PAEs has become a hot topic of widespread concern. This study systematically reviewed the adverse effects of multiple PAEs on the HPG axis in different models and objectively discussed the possible underlying mechanisms. The abnormal release of gonadotropin-releasing hormone and gonadotropin, dysfunction of sex hormone receptors and steroid hormone synthesis, and general damage, including cell proliferation, oxidative stress, apoptosis, and autophagy have been confirmed to be involved in this process. Although it is widely established that PAEs induce HPG axis dysfunction, the specific mechanisms involved remain unclear. From a systematic review of relevant publications, it appears that the abnormal expression of peroxisome proliferator-activated, aryl hydrocarbon, and insulin receptors mediated by PAEs is key upstream event that induces these adverse outcomes; however, this inference needs to be further verified. Overall, this study aimed to provide reliable potential biomarkers for future environmental risk assessment and epidemiological investigation of PAEs.

Serum levels of polychlorinated biphenyls and polybrominated diphenyl ethers in early pregnancy and their associations with gestational diabetes mellitus

Polychlorinated Biphenyls (PCBs) and Polybrominated Diphenyl Ethers (PBDEs) are extensively present in humans and may disturb glucose metabolism during pregnancy. However, previous reports on the associations between PCBs/PBDEs levels and gestational diabetes mellitus (GDM) have been inconsistent. We performed a nested case-control study to measure the serum levels of 6 PCB and 7 PBDE congeners in early pregnancy, and to assess their associations with GDM risk and blood glucose levels. Totally, 208 serum samples (104 GDM cases and 104 controls) were included based on a prospective cohort which was carried out in Jiangsu province, China, from 2020 to 2022. The results showed that PCB-153 was the major PCB congener, whereas PBDE-47 was the predominant PBDE congener. The continuous concentrations of PCB-153, PBDE-28, and total PCB were significantly related to an increased risk of GDM, with adjusted ORs (95%CI) of 1.25 (1.04-1.50), 1.19 (1.02-1.39), and 1.37 (1.05-1.79), respectively. Potential dose-response relationships were also observed between serum levels of PCB-153 (P = 0.011), PBDE-28 (P = 0.028), total PCB (P = 0.048), and total PCB/PBDE (P = 0.010) and GDM risk. Moreover, PCB-153, PBDE-28 and total PCB levels were positively related to 1-h OGTT blood glucose (adjusted βPCB-153: 0.14, 95%CI: 0.00-0.28; adjusted βPBDE-28: 0.20, 95%CI: 0.08-0.32; adjusted βtotal PCB: 0.30, 95%CI: 0.09-0.50), whereas none of the PCBs/PBDEs were statistically related to fasting blood glucose and 2-h OGTT blood glucose (all P > 0.05). Further meta-analysis also supported the association of PCBs exposure with GDM risk. Our study provides further evidence that PCBs/PBDEs exposure may increase GDM risk during pregnancy.

The Relationship between Phthalates and Diabetes: A Review

Since the beginning of their production, in the 1930s, phthalates have been widely used in the plastics industry to provide durability and elasticity to polymers that would otherwise be rigid, or as solvents in hygiene and cosmetic products. Taking into account their wide range of applications, it is easy to understand why their use has been increasing over the years, making them ubiquitous in the environment. This way, all living organisms are easily exposed to these compounds, which have already been classified as endocrine disruptor compounds (EDC), affecting hormone homeostasis. Along with this increase in phthalate-containing products, the incidence of several metabolic diseases has also been rising, namely diabetes. That said, and considering that factors such as obesity and genetics are not enough to explain this substantial increase, it has been proposed that the exposure to environmental contaminants may also be a risk factor for diabetes. Thus, the aim of this work is to review whether there is an association between the exposure to phthalates and the development of the several forms of diabetes mellitus, during pregnancy, childhood, and adulthood.