In vitro and in vivo exposure of endothelial cells to dibutyl phthalate promotes monocyte adhesion

The effect of endothelial cells' exposure to dibutyl phthalate (DBP) on monocyte adhesion is largely unknown. We evaluated monocyte adhesion to DBP-exposed endothelial cells by combining three approaches: short-term exposure (24 h) of EA.hy926 cells to 10-6, 10-5, and 10-4 M DBP, long-term exposure (12 weeks) of EA.hy926 cells to 10-9, 10-8, and 10-7 M DBP, and exposure of rats (28 and 90 days) to 100, 500, and 5000 mg DBP/kg food. Monocyte adhesion to human EA.hy926 and rat aortic endothelial cells, expression of selected cellular adhesion molecules and chemokines, and the involvement of extracellular signal-regulated kinase 1/2 (ERK1/2) were analyzed. We observed increased monocyte adhesion to DBP-exposed EA.hy926 cells in vitro and to rat aortic endothelium ex vivo. ERK1/2 inhibitor prevented monocyte adhesion to DBP-exposed EA.hy926 cells in short-term exposure experiments. Increased ERK1/2 phosphorylation in rat aortic endothelium and transient decrease in ERK1/2 activation following long-term exposure of EA.hy926 cells to DBP were also observed. In summary, exposure of endothelial cells to DBP promotes monocyte adhesion, thus suggesting a possible role for this phthalate in the development of atherosclerosis. ERK1/2 signaling could be the mediator of monocyte adhesion to DBP-exposed endothelial cells, but only after short-term high-level exposure.

Toxic effects of triclosan in aquatic organisms: A review focusing on single and combined exposure of environmental conditions and pollutants

Triclosan (TCS) is an antibacterial agent commonly used in personal care products. Due to its widespread use and improper disposal, it is also a pervasive contaminant, particularly in aquatic environments. When released into water bodies, TCS can induce deleterious effects on developmental and physiological aspects of aquatic organisms and also interact with environmental stressors such as weather, metals, pharmaceuticals, and microplastics. Multiple studies have described the adverse effects of TCS on aquatic organisms, but few have reported on the interactions between TCS and other environmental conditions and pollutants. Because aquatic environments include a mix of contaminants and natural factors can correlate with contaminants, it is important to understand the toxicological outcomes of combinations of substances. Due to its lipophilic characteristics, TCS can interact with a wide range of substances and environmental stressors in aquatic environments. Here, we identify a need for caution when using TCS by describing not only the effects of exposure to TCS alone on aquatic organisms but also how toxicity changes when it acts in combination with multiple environmental stressors.

Evaluation of Lipids and Lipid-Related Transcripts in Human and Ovine Theca Cells and an in Vitro Mouse Model Exposed to the Obesogen Chemical Tributyltin

BACKGROUND

Exposure to obesogenic chemicals has been reported to result in enhanced adipogenesis, higher adipose tissue accumulation, and reduced ovarian hormonal synthesis and follicular function. We have reported that organotins [tributyltin (TBT) and triphenyltin (TPT)] dysregulate cholesterol trafficking in ovarian theca cells, but, whether organotins also exert lipogenic effects on ovarian cells remains unexplored.

OBJECTIVE

We investigated if environmentally relevant exposures to organotins [TBT, TPT, or dibutyltin (DBT)] induce lipid dysregulation in ovarian theca cells and the role of the liver X receptor (LXR) in this effect. We also tested the effect of TBT on oocyte maturation and neutral lipid accumulation, and lipid-related transcript expression in cumulus cells and preimplantation embryos.

METHODS

Primary theca cell cultures derived from human and ovine ovaries were exposed to TBT, TPT, or DBT (1, 10, or 50   ng / ml ). The effect of these chemical exposures on neutral lipid accumulation, lipid abundance and composition, lipid homeostasis-related gene expression, and cytokine secretion was evaluated using liquid chromatography-mass spectrometry (LC-MS), inhibitor-based methods, cytokine secretion, and lipid ontology analyses. We also exposed murine cumulus-oocyte complexes to TBT and evaluated oocyte maturation, embryo development, and lipid homeostasis-related mRNA expression in cumulus cells and blastocysts.

RESULTS

Exposure to TBT resulted in higher intracellular neutral lipids in human and ovine primary theca cells. In ovine theca cells, this effect was dose-dependent, independent of cell stage, and partially mediated by LXR. DBT and TPT resulted in higher intracellular neutral lipids but to a lesser extent in comparison with TBT. More than 140 lipids and 9 cytokines were dysregulated in TBT-exposed human theca cells. Expression of genes involved in lipogenesis and fatty acid synthesis were higher in theca cells, as well as in cumulus cells and blastocysts exposed to TBT. However, TBT did not impact the rates of oocyte maturation or blastocyst development.

DISCUSSION

TBT induced dyslipidemia in primary human and ovine theca cells, which may be responsible for some of the TBT-induced fertility dysregulations reported in rodent models of TBT exposure. https://doi.org/10.1289/EHP13955.

The adverse role of endocrine disrupting chemicals in the reproductive system

Reproductive system diseases pose prominent threats to human physical and mental well-being. Besides being influenced by genetic material regulation and changes in lifestyle, the occurrence of these diseases is closely connected to exposure to harmful substances in the environment. Endocrine disrupting chemicals (EDCs), characterized by hormone-like effects, have a wide range of influences on the reproductive system. EDCs are ubiquitous in the natural environment and are present in a wide range of industrial and everyday products. Currently, thousands of chemicals have been reported to exhibit endocrine effects, and this number is likely to increase as the testing for potential EDCs has not been consistently required, and obtaining data has been limited, partly due to the long latency of many diseases. The ability to avoid exposure to EDCs, especially those of artificially synthesized origin, is increasingly challenging. While EDCs can be divided into persistent and non-persistent depending on their degree of degradation, due to the recent uptick in research studies in this area, we have chosen to focus on the research pertaining to the detrimental effects on reproductive health of exposure to several EDCs that are widely encountered in daily life over the past six years, specifically bisphenol A (BPA), phthalates (PAEs), polychlorinated biphenyls (PCBs), parabens, pesticides, heavy metals, and so on. By focusing on the impact of EDCs on the hypothalamic-pituitary-gonadal (HPG) axis, which leads to the occurrence and development of reproductive system diseases, this review aims to provide new insights into the molecular mechanisms of EDCs' damage to human health and to encourage further in-depth research to clarify the potentially harmful effects of EDC exposure through various other mechanisms. Ultimately, it offers a scientific basis to enhance EDCs risk management, an endeavor of significant scientific and societal importance for safeguarding reproductive health.

Emerging pollutants in etiology and pathophysiology of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a multifactorial endocrine disorder affecting reproductive-aged women worldwide. Although genetic and lifestyle factors have been implicated in its etiology, emerging evidence suggests that exposure to environmental pollutants may also contribute significantly to the development and pathophysiology of PCOS. This review article aims to provide a comprehensive overview of the potential role of emerging pollutants, including pharmaceuticals and personal care products (PPCPs), microplastics, endocrine disruptors, and nanoparticles, in PCOS development. The article summarizes the current understanding of PCOS pathogenesis and its clinical manifestations. Subsequently, it delves into the mechanisms of action of the emerging pollutants, exploring how they may disrupt the endocrine system, interfere with hormonal regulation, and contribute to the manifestation of PCOS symptoms. Moreover, the potential for cumulative effects and synergistic interactions between these pollutants demands a cautious approach when considering their role in PCOS etiology.

Facile synthesis of Cu2+-immobilized magnetic covalent organic frameworks for highly efficient enrichment and sensitive determination of five phthalate monoesters from mouse plasma with HPLC-MS/MS

Development of a simple, highly selective, and sensitive analytical method for phthalate monoesters (mPAEs) remains a challenge due to the complexity of biological samples. To address this issue, Cu²⁺ immobilized magnetic covalent organic frameworks (Fe₃O₄@TtDt@Cu²⁺ composites) with core-shell structures were prepared to enhance the enrichment efficiency of mPAEs by a facile approach synthesis of COFs shells with inherent bifunctional groups on Fe₃O₄ NPs and further Cu²⁺ immobilization. The composites exhibit high specific surface area (348.1 m² g^-1), outstanding saturation magnetization (34.94 emu g^-1), ordered mesoporous structure, Cu²⁺ immobilization, and excellent thermal stability. Accordingly, a magnetic solid-phase extraction (MSPE) pretreatment technique based on Cu²⁺ immobilized COF composites combined with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was established, and key parameters including the adsorbent amount, adsorption time, elution solvent, etc. were examined in detail. The developed analytical method showed wide linear ranges (10-8000 ng L^-1), low limit of detections (LODs, 2-10 ng L^-1), and good correlation coefficients (R² ≥ 0.9904) for the five mPAEs. Furthermore, the analytical method was also successfully applied to the highly sensitive detection of metabolite mPAEs in mouse plasma samples, indicating the promising application of the Fe₃O₄@TtDt@Cu²⁺ composites as a quick and efficient adsorbent in the sample pretreatment.

Polycystic Ovary Syndrome and Endocrine Disruptors (Bisphenols, Parabens, and Triclosan)-A Systematic Review

Exposure to endocrine disrupting chemicals (EDCs) can result in alterations of the female reproductive system, including polycystic ovary syndrome (PCOS). The aim of this review was to summarize the knowledge about the association of EDCs (bisphenols, parabens, and triclosan) with PCOS. We conducted an electronic literature search using PubMed for studies published between January 2007 and October 2022 on EDCs related to PCOS, and evaluated the association of PCOS with bisphenols, parabens and triclosan in 15 articles. Most studies revealed significantly higher plasma, urinary or follicular fluid levels of bisphenol A (BPA) in women with PCOS, and some showed a positive correlation of BPA with insulin resistance, polycystic morphology on ultrasound, hepatic steatosis, bilirubin levels, as well as free androgen index, androstenedione and testosterone serum levels, and markers of low-grade chronic inflammation. There was a negative correlation of BPA with markers of ovarian reserve, sex hormone binding globulin and vitamin D-binding protein. Parabens and triclosan have been studied in only one study each, with no significant associations with PCOS observed. Our review revealed an association of BPA with PCOS and negative effects of BPA on human ovaries; more research is needed to assess the potential associations of parabens and triclosan with PCOS.

Urinary phthalate metabolite concentrations and serum hormone levels in pre- and perimenopausal women from the Midlife Women's Health Study

BACKGROUND

Phthalate exposure is associated with altered reproductive function, but little is known about associations between phthalate and hormone levels in midlife women.

METHODS

This cross-sectional analysis includes 45-54-year-old pre- and perimenopausal women from Baltimore, MD and its surrounding counties enrolled in the Midlife Women's Health Study (n = 718). Serum and urine samples were collected from participants once a week for four consecutive weeks to span the menstrual cycle. Serum samples were assayed for estradiol, testosterone, progesterone, sex hormone binding globulin (SHBG), follicle-stimulating hormone (FSH), and anti-Müllerian hormone (AMH), and geometric means were calculated for each hormone across all four weeks. Urine samples were analyzed for nine phthalate metabolites from pools of one-to-four urine samples. Phthalate metabolite concentrations were specific gravity-adjusted and assessed as individual metabolites or as molar sums of metabolites from common parents (di(2-ethylhexyl) phthalate metabolites, ∑DEHP), exposure sources (plastic, ∑Plastics; personal care products, ∑PCP), biological activity (anti-androgenic, ∑AA), and sum of all metabolites (∑Phthalates). We used linear regression models to assess overall associations of phthalate metabolites with hormones, controlling for important demographic, lifestyle, and health factors. We also explored whether associations differed by menopause status, body mass index (BMI), and race/ethnicity.

RESULTS

Most participants were non-Hispanic white (67%) or black (29%), college-educated (65%), employed (80%), and had somewhat higher mean urinary phthalate metabolite concentrations than other U.S. women. Overall, the following positive associations were observed between phthalate metabolites and hormones: ∑DEHP (%Δ: 4.9; 95%CI: 0.5, 9.6), ∑Plastics (%Δ: 5.1; 95%CI: 0.3, 10.0), and ∑AA (%Δ: 7.8; 95%CI: 2.3, 13.6) with estradiol; MiBP (%Δ: 6.6; 95%CI: 1.5, 12.1) with testosterone; ∑DEHP (%Δ: 8.3; 95%CI: 1.5, 15.6), ∑Plastics (%Δ: 9.8; 95%CI: 2.4, 17.7), MEP (%Δ: 4.6; 95%CI: 0.1, 9.2), ∑PCP (%Δ: 6.0; 95%CI: 0.2, 12.2), ∑Phthalates (%Δ: 9.0; 95%CI: 2.1, 16.5), and ∑AA (%Δ: 12.9; 95%CI: 4.4, 22.1) with progesterone; and MBP (%Δ: 8.5; 95%CI: 1.2, 16.3) and ∑AA (%Δ: 9.0; 95%CI: 1.3, 17.4) with AMH. Associations of phthalate metabolites with hormones differed by menopause status (strongest in premenopausal women for estradiol, progesterone, and FSH), BMI (strongest in obese women for progesterone), and race/ethnicity (strongest in non-Hispanic white women for estradiol and AMH).

CONCLUSIONS

We found that phthalate metabolites were positively associated with several hormones in midlife women, and that some demographic and lifestyle characteristics modified these associations. Future longitudinal studies are needed to corroborate these findings in more diverse midlife populations.

Cumulative risk assessment of phthalates exposure for recurrent pregnancy loss in reproductive-aged women population using multiple hazard indices approaches

Phthalates, which are commonly used in flexible plastics and consumer products, have been reported to be toxic to reproductive and developmental function in mammals. Past studies have focused on the toxic effects on male reproduction, with only a few studies conducted on the risks that cumulative exposure to phthalates have on the female reproductive system. We recruited 260 patients with recurrent pregnancy loss (RPL) of unknown etiology and 203 controls from the clinics of Obstetrics and Gynecology at a medical center in southern Taiwan from 2013 to 2020. The daily intake of phthalates was estimated from urine samples using the back-calculation method, after which the cumulative risk was determined using multiple hazard indices, including a dose-addition model, a receptor effect model, and a hazard index approach. The patients with RPL had a significantly higher cumulative exposure to phthalates (p < 0.05) than did the controls with a hazard index above one. After adjusted logistic regression analysis, we found that the risk of RPL was strongly related to the higher quartiles of DEHP, the DEHP_TEQ for the antiandrogenic effect and adverse effects of the female reproductive system and the ER_α binding effect (p < 0.05). Our work suggests that more attentions should be paid to the adverse effects induced by phthalates on female reproduction, especially the effects caused by the cumulative exposure to phthalates in women of reproductive age.

Propylparaben concentrations in the urine of women and adverse effects on ovarian function in mice in vivo and ovarian cells in vitro

Female reproduction is precisely regulated by hormones, and the ovary is easily affected by environmental endocrine disruptors (EDCs), which are ubiquitous in industrialized societies. Parabens are EDCs that are used as antibacterial preservatives in cosmetics, personal care products (PCPs), medicines, and food. We used ultrahigh-performance liquid chromatography-mass spectrometry to quantitatively detect methyl-, ethyl-, butyl-, and propylparaben (PP) concentrations in urine samples from 74 women of childbearing age. Balb/c mice were subcutaneously injected with 100 mg/kg/day of PP for 21 consecutive days or 100 or 1,000 mg/kg/day of PP during superovulation. Various concentrations of PP (ranging from 1 to 1,000 nM) were added to a human ovarian granulosa tumor-derived cell line (KGN) culture for 24 h. The urinary paraben concentrations of women who used cosmetics and other PCPs within 48 h prior to sample collection were significantly elevated, and the PP concentration was significantly positively correlated with the basal estradiol concentration. After PP injection, the mouse serum estradiol concentrations were significantly increased, estrus cycles were disordered, corpus luteum number was reduced, and number of oocytes retrieved was significantly reduced. In in vitro experiments, PP treatment increased estradiol synthesis and the expression levels of aromatase enzyme (CYP19A1) and steroidogenic acute regulatory protein. This study demonstrates the adverse effects of PP on ovarian estradiol secretion and ovulation, further evaluates the safety of PP as a preservative, and provides guidance for the use of PCPs and cosmetics by women of childbearing age.

Environmentally relevant mixtures of phthalates and phthalate metabolites differentially alter the cell cycle and apoptosis in mouse neonatal ovaries†

Phthalates are a group of chemicals used as additives in various consumer products, medical equipment, and personal care products. Phthalates and their metabolites are consistently detected in humans, indicating widespread and continuous exposure to multiple phthalates. Thus, environmentally relevant mixtures of phthalates and phthalate metabolites were investigated to determine the effects of phthalates on the function of the ovary during the neonatal period of development. Neonatal ovaries from CD-1 mice were cultured with dimethyl sulphoxide (DMSO; vehicle control), phthalate mixture (0.1-100 μg/mL), or phthalate metabolite mixture (0.1-100 μg/mL). The phthalate mixture was composed of 35% diethyl phthalate, 21% di(2-ethylhexyl) phthalate, 15% dibutyl phthalate, 15% diisononyl phthalate, 8% diisobutyl phthalate, and 5% benzylbutyl phthalate. The phthalate metabolite mixture was composed of 37% monoethyl phthalate, 19% mono(2-ethylhexyl) phthalate, 15% monobutyl phthalate, 10% monoisononyl phthalate, 10% monoisobutyl phthalate, and 8% monobenzyl phthalate. After 96 h of culture, ovaries were harvested for histological analysis of folliculogenesis, gene expression analysis of cell cycle and apoptosis regulators, and immune staining for cell proliferation and apoptosis. The metabolite mixture significantly decreased the number and percentage of abnormal follicles (100 μg/mL) compared to controls. The metabolite mixture also significantly increased the expression of cell cycle inhibitors (100 μg/mL) and the antiapoptotic factor Bcl2l10 (10 μg/mL) compared to controls. The phthalate mixture did not significantly alter gene expression or follicle counts, but ovaries exposed to the phthalate mixture (0.1 μg/mL) exhibited marginally significantly increased apoptosis as revealed by DNA fragmentation staining. Overall, these data show that parent phthalates and phthalate metabolites differentially impact ovarian function.

Bisphenol S enhances gap junction intercellular communication in ovarian theca cells

Gap junction intercellular communication (GJIC) is necessary for ovarian function, and it is temporospatially regulated during follicular development and ovulation. At outermost layer of the antral follicle, theca cells provide structural, steroidogenic, and vascular support. Inter- and extra-thecal GJIC is required for intrafollicular trafficking of signaling molecules. Because GJIC can be altered by hormones and endocrine disrupting chemicals (EDCs), we tested if any of five common EDCs (bisphenol A (BPA), bisphenol S (BPS), bisphenol F (BPF), perfluorooctanesulfonic acid (PFOS), and triphenyltin chloride (TPT)) can interfere with theca cell GJIC. Since most chemicals are reported to repress GJIC, we hypothesized that all chemicals tested, within environmentally relevant human exposure concentrations, will inhibit theca cell GJICs. To evaluate this hypothesis, we used a scrape loading/dye transfer assay. BPS, but no other chemical tested, enhanced GJIC in a dose- and time-dependent manner in ovine primary theca cells. A signal-protein inhibitor approach was used to explore the GJIC-modulatory pathways involved. Phospholipase C and mitogen-activated protein kinase (MAPK) inhibitors significantly attenuated BPS-induced enhanced GJIC. Human theca cells were used to evaluate translational relevance of these findings. Human primary theca cells had a ∼40% increase in GJIC in response to BPS, which was attenuated with a MAPK inhibitor, suggestive of a conserved mechanism. Upregulation of GJIC could result in hyperplasia of the theca cell layer or prevent ovulation by holding the oocyte in meiotic arrest. Further studies are necessary to understand in vitro to in vivo translatability of these findings on follicle development and fertility outcomes.

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) and their effects on the ovary

BACKGROUND

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are found widespread in drinking water, foods, food packaging materials and other consumer products. Several PFAS have been identified as endocrine-disrupting chemicals based on their ability to interfere with normal reproductive function and hormonal signalling. Experimental models and epidemiologic studies suggest that PFAS exposures target the ovary and represent major risks for women's health.

OBJECTIVE AND RATIONALE

This review summarises human population and toxicological studies on the association between PFAS exposure and ovarian function.

SEARCH METHODS

A comprehensive review was performed by searching PubMed. Search terms included an extensive list of PFAS and health terms ranging from general keywords (e.g. ovarian, reproductive, follicle, oocyte) to specific keywords (including menarche, menstrual cycle, menopause, primary ovarian insufficiency/premature ovarian failure, steroid hormones), based on the authors' knowledge of the topic and key terms.

OUTCOMES

Clinical evidence demonstrates the presence of PFAS in follicular fluid and their ability to pass through the blood-follicle barrier. Although some studies found no evidence associating PFAS exposure with disruption in ovarian function, numerous epidemiologic studies, mostly with cross-sectional study designs, have identified associations of higher PFAS exposure with later menarche, irregular menstrual cycles, longer cycle length, earlier age of menopause and reduced levels of oestrogens and androgens. Adverse effects of PFAS on ovarian folliculogenesis and steroidogenesis have been confirmed in experimental models. Based on laboratory research findings, PFAS could diminish ovarian reserve and reduce endogenous hormone synthesis through activating peroxisome proliferator-activated receptors, disrupting gap junction intercellular communication between oocyte and granulosa cells, inducing thyroid hormone deficiency, antagonising ovarian enzyme activities involved in ovarian steroidogenesis or inhibiting kisspeptin signalling in the hypothalamus.

WIDER IMPLICATIONS

The published literature supports associations between PFAS exposure and adverse reproductive outcomes; however, the evidence remains insufficient to infer a causal relationship between PFAS exposure and ovarian disorders. Thus, more research is warranted. PFAS are of significant concern because these chemicals are ubiquitous and persistent in the environment and in humans. Moreover, susceptible groups, such as foetuses and pregnant women, may be exposed to harmful combinations of chemicals that include PFAS. However, the role environmental exposures play in reproductive disorders has received little attention by the medical community. To better understand the potential risk of PFAS on human ovarian function, additional experimental studies using PFAS doses equivalent to the exposure levels found in the general human population and mixtures of compounds are required. Prospective investigations in human populations are also warranted to ensure the temporality of PFAS exposure and health endpoints and to minimise the possibility of reverse causality.

Butylparaben Is Toxic to Porcine Oocyte Maturation and Subsequent Embryonic Development Following In Vitro Fertilization

Parabens are widely used in personal care products due to their antimicrobial effects. Although the toxicity of parabens has been reported, little information is available on the toxicity of butylparaben (BP) on oocyte maturation. Therefore, we investigated the effects of various concentrations of BP (0 μM, 100 μM, 200 μM, 300 μM, 400 μM, and 500 μM) on the in vitro maturation of porcine oocytes. BP supplementation at a concentration greater than 300 μM significantly reduced the proportion of complete cumulus cell expansion and metaphase II oocytes compared to the control. The 300 μM BP significantly decreased fertilization, cleavage, and blastocyst formation rates with lower total cell numbers and a higher rate of apoptosis in blastocysts compared to the control. The BP-treated oocytes showed significantly higher reactive oxygen species (ROS) levels, and lower glutathione (GSH) levels than the control. BP significantly increased the aberrant mitochondrial distribution and decreased mitochondrial function compared to the control. BP-treated oocytes exhibited significantly higher percentage of γ-H2AX, annexin V-positive oocytes and expression of LC3 than the control. In conclusion, we demonstrated that BP impaired oocyte maturation and subsequent embryonic development, by inducing ROS generation and reducing GSH levels. Furthermore, BP disrupted mitochondrial function and triggered DNA damage, early apoptosis, and autophagy in oocytes.

The Norwegian biomonitoring study from the EU project EuroMix: Levels of phenols and phthalates in 24-hour urine samples and exposure sources from food and personal care products

BACKGROUND

Exposure to multiple chemicals occurs daily through several routes; diet, inhalation and dermal contact. Real-life exposure assessment is needed to understand the risk. Therefore, a human biomonitoring (BM) study was performed to examine the plausibility of source-to-dose calculations for chemical mixtures in the Horizon 2020 EuroMix project.

OBJECTIVES

To provide a detailed description of the design of the EuroMix BM study, and to present the initial results for urinary phenols and phthalates and to describe their exposure determinants from foods and personal care products (PCPs).

METHOD

Adults (44 males and 100 females) kept detailed diaries on their food consumption, PCP use and handling of cash receipts. Urine samples were collected over the same 24-hour period. Urinary levels of four parabens, five bisphenols, oxybenzone/benzophenone-3 (OXBE), triclosan (TCS), triclocarban (TCC) and metabolites of eight phthalates and 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH) were analysed by ultra-high-performance liquid chromatography and tandem mass spectrometry. Multivariable linear regressions were performed between PCPs/food categories and each dependent chemical variable separately, and were only sex-stratified when an interactions between sex and the independent variable was significant.

RESULTS

The detection rate for the metabolites of phthalates and DINCH, and bisphenol A (BPA) and TCS in urine was 88-100%, while bisphenol S (BPS) and bisphenol F (BPF) were only found in 29% and 4% of the urine samples, respectively. Bisphenol B (BPB), bisphenol AF (BPAF) and TCC were not detected. Food groups associated with phenol exposure were meat, bread, beverages and butter and oil. Food determinants for phthalate exposure were sweets, butter and oil, fruit and berries and other foods. The only positive association between the use of PCPs and phenols was found between BPA and lip gloss/balm. Phthalate exposure was associated with the use of shower gel, hand cream (females), toothpaste, anti-wrinkle cream (females) and shaving products (males).

CONCLUSION

The participants in the EuroMix BM study were exposed to a mixture of phenols and phthalates. A variety of food categories and PCPs were found to be possible sources of these chemicals. This indicates a complex pattern of exposure to numerous chemicals from multiple sources, depending on individual diet and PCP preferences.

Propylparaben inhibits mouse cultured antral follicle growth, alters steroidogenesis, and upregulates levels of cell-cycle and apoptosis regulators

Propylparaben is prevalently used in cosmetics, pharmaceuticals, and foods; yet, its direct effects on the mammalian ovary are unknown. We investigated the direct effects of propylparaben on the growth and steroidogenic function of mouse antral follicles. Antral follicles were isolated from the ovaries of Swiss mice (age: 32-42 days) and cultured in media with dimethylsulfoxide vehicle control or propylparaben (0.01-100 μg/mL) for 24-72 h. Follicle diameter was measured every 24 h to assess growth. Follicles and media were collected at 24 and 72 h for gene expression and hormone measurements. Propylparaben (100 μg/mL) significantly inhibited follicle growth (48-72 h). Further, propylparaben exposure increased expression of cell cycle regulators (Cdk4, Cdkn1a), an apoptotic factor (Bax), and a key steroidogenic regulator (Star). In media, propylparaben decreased accumulation of dehydroepiandrosterone-sulfate, but increased testosterone and 17β-estradiol. Overall, our findings suggest that propylparaben disrupts antral follicle growth and steroidogenic function by altering the cell-cycle, apoptosis, and steroidogenesis pathways.

Ovarian Metabolism of an Environmentally Relevant Phthalate Mixture

Phthalates are synthetic chemicals with widespread human exposure due to their use as additives in consumer products. Phthalate diesters are hydrolyzed in the environment and in the body to monoesters that may be more toxic than the parent compounds. This study tested the hypothesis that adult mouse antral follicles, but not neonatal ovaries, are able to metabolize an environmentally relevant mixture of phthalates. Whole neonatal ovaries and isolated adult antral follicles from CD-1 mice were cultured in media treated with vehicle control or 0.1-10 µg/ml of a mixture composed of 35% diethyl phthalate (DEP), 21% di(2-ethylhexyl) phthalate (DEHP), 15% dibutyl phthalate (DBP), 15% diisononyl phthalate (DiNP), 8% diisobutyl phthalate (DiBP), and 5% benzylbutyl phthalate (BzBP). After 4 days of culture, media were subjected to high-performance liquid chromatography tandem mass spectrometry to measure the amounts of diester phthalates and monoester metabolites. Ovaries and follicles were collected to measure the gene and protein expression of the enzymes required for phthalate metabolism. Monoester metabolites for all phthalates except DiNP were detected in the media for both culture types at most doses. The long-chain phthalates (BzBP, DEHP, and DiNP) were metabolized less than the short-chain phthalates (DEP, DBP, and DiBP) compared with respective controls. Expression of metabolizing enzymes was observed for all treatment groups in both culture types. These data indicate that mouse ovaries are capable of metabolizing low doses of phthalates and suggest that metabolic capacity differs for follicles at different stages of development.

Multispecies study: low-dose tributyltin impairs ovarian theca cell cholesterol homeostasis through the RXR pathway in five mammalian species including humans

Tributyltin (TBT), an organotin chemical used as a catalyst and biocide, can stimulate cholesterol efflux in non-steroidogenic cells. Since cholesterol is the first limiting step for sex hormone production, we hypothesized that TBT disrupts intracellular cholesterol transport and impairs steroidogenesis in ovarian theca cells. We investigated TBT's effect on cholesterol trafficking, luteinization, and steroidogenesis in theca cells of five species (human, sheep, cow, pig, and mice). Primary theca cells were exposed to an environmentally relevant dose of TBT (1 or 10 ng/ml) and/or retinoid X receptor (RXR) antagonist. The expression of RXRα in sheep theca cells was knocked down using shRNA. Steroidogenic enzymes, cholesterol transport factors, and nuclear receptors were measured by RT-qPCR and Western blotting, and intracellular cholesterol, progesterone, and testosterone secretion by ELISA. TBT upregulated StAR and ABCA1 in ovine cells, and SREBF1 mRNA in theca cells. TBT also reduced intracellular cholesterol and upregulated ABCA1 protein expression but did not alter testosterone or progesterone production. RXR antagonist and RXRα knockdown demonstrates that TBT's effect is partially through RXR. TBT's effect on ABCA1 and StAR expression was recapitulated in all five species. TBT, at an environmentally relevant dose, stimulates theca cell cholesterol extracellular efflux via the RXR pathway, triggers a compensatory upregulation of StAR that regulates cholesterol transfer into the mitochondria and SREBF1 for de novo cholesterol synthesis. Similar results were obtained in all five species evaluated (human, sheep, cow, pig, and mice) and are supportive of TBT's conserved mechanism of action across mammalian species.

The effects of Bisphenol A (BPA) on sympathetic nerve fibers in the uterine wall of the domestic pig

Bisphenol A (BPA), used in the production of plastic, shows multidirectional negative effects on the living organism. BPA may affect the reproductive and nervous systems; however, its influence on the nerves supplying the uterus has not been studied. During the present study, the impact of BPA on the sympathetic nerves in the uterus was investigated using a double immunofluorescence technique. The results have shown that even low doses of BPA may change the neurochemical characterization of uterine sympathetic nerves, and the severity of these changes depends on the part of the uterus and the dose of the toxic substance. Probably the changes observed during the present study resulted from the neurotoxic and/or pro-inflammatory activity of BPA, but the exact mechanism for the observed fluctuation still remains unknown. The fluctuations of the neurochemical characterization of the uterine intramural nerves may be the first subclinical signs of harmful exposure to BPA.