Urinary phthalate metabolites and ovarian reserve among women seeking infertility care

Health Risk Assessment of Occupational Exposures of Polycyclic Aromatic Hydrocarbons, Phthalates, and Semi-Volatile Chlorinated Organic Compounds in Urine of Commercial Fish Smokers, Ghana

Occupational exposure to smoke and polycyclic aromatic hydrocarbons (PAHs) poses significant health risks, especially for commercial fish smokers who are regularly exposed to high levels of smoke and particulate matter. This study aimed to evaluate the exposure levels and assess the health risks associated with PAHs, phenols, phthalates, and substituted benzenes among 155 fish smokers in Ghana. A total of 155 urine samples from fish smokers across selected coastal regions in Ghana were collected and analyzed. The sample preparation was conducted using the Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERs) method, as standardized by the Association of Official Analytical Chemists (A.O.A.C.). Analysis was performed utilizing the Shimadzu GC-MS QP 2020. The type of firewood used by fish smokers significantly influenced the levels of PAHs detected in the urine samples. Hardwoods such as odum, acacia, and cocoa, with their dense structures and combustion characteristics, were found to produce higher levels of PAHs. In contrast, softer woods like sugar cane and palm kernel released lower PAH levels during combustion. The findings indicate that fish smokers utilizing various wood types and unfiltered ovens, specifically the "Chorkor Oven," are exposed to elevated levels of PAHs, phenols, phthalates, and substituted benzenes through inhalation during work hours. Cancer risk assessments revealed risk levels for PAHs ranging from 6.00E-04 to 4.14E-01, phenols from 0.00E+00 to 3.70E-01, substituted benzenes from 9.04E-08 to 1.99E-01, and phthalates from 3E-04 to 2.09E+04. These values exceed the limits by the U.S. Environmental Protection Agency (U.S.E.P.A.) of 10E-06. Furthermore, the estimated non-cancer hazard quotient values for hydrocarbons ranged from 8.42E+00 to 1.99E+01, all exceeding the threshold of 1, as outlined by both the U.S.E.P.A. and the World Health Organization (WHO), indicating substantial potential health risks for commercial fish smokers.

Network toxicology and cell experiments reveal the mechanism of DEHP-induced diabetic nephropathy via Wnt signaling pathway

Di(2-ethylhexyl) phthalate (DEHP), a widely recognized endocrine disruptor, has been linked to the pathogenesis of diabetic nephropathy (DN) through its interference with hormonal and metabolic homeostasis. This study integrates network toxicology with cell-based assays to elucidate the molecular mechanisms of DEHP-induced DN, seeking to identify novel targets for toxicity assessment and therapeutic intervention. Through comprehensive screening across multiple toxicology and disease-related databases, six core genes (CTNNB1, EGFR, TNF, CCND1, BCL2, CASP3) were identified as shared mediators of DEHP exposure and DN. These genes are predominantly associated with the Wnt signaling pathway, a pivotal regulator of podocyte function, including cellular adhesion, differentiation, apoptosis, and inflammatory response. Mouse glomerular podocytes (MPC-5) exposed to graded concentrations of DEHP, with or without the Wnt pathway inhibitor XAV-939, displayed significant DEHP-induced disruptions: reduced cell adhesion, proliferation, and differentiation; increased autophagy, apoptosis, and migratory activity; elevated inflammatory mediator release; and pronounced activation of the Wnt signaling pathway, evidenced by upregulation of β-catenin, EGFR, TNF, CCND1, BCL2 and downregulation of CASP3. DEHP exposure further altered transcriptional activity and chromatin structure at key loci (CTNNB1, EGFR, and TNF). XAV-939 effectively mitigated these effects, underscoring the Wnt pathway's central role in DN progression under DEHP influence. These findings highlight the complex multi-target, multi-pathway interactions of DEHP in DN pathophysiology, offering deeper mechanistic insights and potential targets for therapeutic intervention against DEHP-induced nephrotoxicity.

Novel Insight into the mechanism of di (2-ethylhexyl) phthalate (DEHP) impairing early follicle development

Di (2-ethylhexyl) phthalate (DEHP), an artificially synthetic plasticizer, is a widespread environmental endocrine disruptor, which has raised substantial concern among the public about its potential reproductive toxicity effects. Taking large amounts of DEHP disrupts the normal functioning of the ovaries, however, the toxicological effects and the mechanisms by which DEHP impairs fetal folliculogenesis remain poorly understood. Our research aims to elucidate the associations between utero exposure to DEHP and fetal folliculogenesis in offspring. In this research, we monitored the spatiotemporal and expression levels of GDF9-Hedgehog (Hh) pathway-related genes during postnatal days 3-14, confirming initially the potential associations between defects in theca cell development and the downregulation of GDF9-Hh signaling. Moreover, utilizing an ovarian organ in vitro culture model, rescue validation experiments demonstrated that the addition of recombinant GDF9 protein effectively alleviate the theca cell damage caused by DEHP, thus supporting the aforementioned associations. In conclusion, our findings validate the significant role of the GDF9-Hh pathway in the enduring reproductive toxicity resulting from prenatal exposure to DEHP.

Quantitative label-free proteomic analysis of mouse ovarian antral follicles following oral exposure to a human-relevant mixture of three phthalates

Dibutyl phthalate (DBP), di-2-ethylhexyl phthalate (DEHP), and benzyl butyl phthalate (BBP) are used in personal and medical care products. In the ovary, antral follicles are essential for steroidogenesis and ovulation. DBP, BBP, and DEHP are known to inhibit mouse antral follicle growth and ovulation in vitro, and associate with decreased antral follicle counts in women. Given that the in vivo effects of a three-phthalate mixture on antral follicles are unknown, we evaluated the effects of a human-relevant mixture of DBP, BBP, and DEHP on ovarian follicles through proteome profiling analysis. Adult CD-1 female mice were fed corn oil (vehicle), or two dose levels of a phthalate mixture based on estimated exposures in general (32 µg/kg/d; PHT 32) and occupationally exposed (500 µg/kg/d; PHT 500) populations for 10 d. Antral follicles (>250 µm) were isolated and subjected to proteome profiling via label-free tandem mass spectrometry. A total of 5,417 antral follicle proteins were detected, of which 194 were differentially abundant between vehicle and PHT 32, and 136 between vehicle and PHT 500. Bioinformatic analysis revealed significantly different responses between the two phthalate doses. Protein abundance differences in the PHT 32 exposure mapped to cytoplasm, mitochondria, and lipid metabolism; whereas those in the PHT 500 exposure mapped to cytoplasm, nucleus, and phosphorylation. When both doses altered proteins mapped to common processes, the associated predicted transcription factors were different. These findings provide novel mechanistic insight into phthalate-associated, ovary-driven reproductive outcomes in women.

Health hazards of preconception phthalate exposure: A scoping review of epidemiology studies

There is a close relationship between preconception health and maternal and child health outcomes, and the consequences may be passed down from generation to generation. In 2018, Lancet published three consecutive articles emphasizing the importance of the preconception period. Phthalic acid ester (PAE) exposure during this period may affect gametogenesis and epigenetic information in gametophytes, thereby affecting embryonic development and offspring health. Therefore, this article reviews the effects of parental preconception PAE exposure on reproductive/birth outcomes and offspring health, to provide new evidence on this topic. We searched Web of Science, MEDLINE (through PubMed), the China National Knowledge Infrastructure (CNKI), ScienceDirect, and the VIP Journal Library from the date of database establishment to July 3, 2024. Finally, 12 articles were included. Three studies investigated the health hazards (effects on birth weight, abortion, etc.) of women's preconception PAE exposure. Nine studies involved both parents. Nine studies considered the impacts of PAE preconception exposure on reproductive/birth outcomes, focusing on birth weight, pregnancy loss, preterm birth, embryo quality, and placental weight. Three studies considered the impacts of preconception PAE exposure on offspring behavior. The results of this review suggested that parental preconception PAE exposure may have an impact on reproductive/birth outcomes and offspring behavior, including birth weight, child behavior, and dietary behavior. However, studies on the health hazards of preconception PAE exposure are relatively scarce, and the outcomes of current studies are varied. It is necessary to use systematic reviews to verify an accurate research question to provide recommendations for public health policy making.

Reduced ovarian cholesterol and steroid biosynthesis along with increased inflammation are associated with high DEHP metabolite levels in human ovarian follicular fluids

The plasticizer di(2-ethylhexyl) phthalate (DEHP) is known to have endocrine-disrupting properties mediated by its many metabolites that form upon exposure in biological systems. In a previous study, we reported an inverse association between DEHP metabolites in the human ovarian follicular fluid (FF) and the responsiveness of the follicles to controlled ovarian stimulation during in vitro fertilization (IVF) treatments. Here, we explored this association further through molecular analysis of the ovarian FF samples. Ninety-six IVF patients from Swedish (N = 48) and Estonian (N = 48) infertility clinics were selected from the previous cohort (N = 333) based on the molar sum of DEHP metabolites in their FF samples to arrive at "high" (mean 7.7 ± SD 2.3 nM, N = 48) and "low" (0.8 ± 0.4 nM, N = 48) exposure groups. Extracellular miRNA levels and concentrations of 15 steroid hormones were measured across FF samples. In addition, FF somatic cells, available for the Estonian patients, were used for RNA sequencing. Differential expression (DE) and interactions between miRNA and mRNA networks revealed that the expression levels of genes in the cholesterol biosynthesis and steroidogenesis pathways were significantly decreased in the high compared to the low DEHP group. In addition, the DE miRNAs were predicted to target key enzymes within these pathways (FDR < 0.05). A decreased 17-OH-progesterone to progesterone ratio was observed in the FF of the high DEHP group (p < 0.05). Additionally, the expression levels of genes associated with inflammatory processes were elevated in the FF somatic cells, and a computational cell-type deconvolution analysis suggested an increased immune cell infiltration into the high DEHP follicles (p < 0.05). In conclusion, elevated DEHP levels in FF were associated with a significantly altered follicular milieu within human ovaries, involving a pro-inflammatory environment and reduced cholesterol metabolism, including steroid synthesis. These results contribute to our understanding of the molecular mechanisms of female reprotoxic effects of DEHP.

Impact of DEHP on mitochondria-associated endoplasmic reticulum membranes and reproductive toxicity in ovary

Di(2-ethylhexyl) phthalate (DEHP) is a widely recognized environmental endocrine disruptor that potentially impacts female reproductive function, although the specific mechanisms leading to such impairment remain unclear. A growing body of research has revealed that the endoplasmic reticulum and mitochondrial function significantly influence oocyte quality. The structure of mitochondria-associated endoplasmic reticulum membranes (MAMs) is crucial for facilitating the exchange of Ca2+, lipids, and metabolites. This study aimed to investigate the alterations in the composition and function of MAMs after DEHP exposure and to elucidate the underlying mechanisms of ovarian toxicity. The female mice were exposed to DEHP at doses of 5 and 500 mg/kg/day for one month. The results revealed that DEHP exposure led to reduced serum anti-Müllerian hormone levels and increased atretic follicles in mice. DEHP induced endoplasmic reticulum stress and disrupted calcium homeostasis in oocytes. Furthermore, DEHP impaired the mitochondrial function of oocytes and reduced their membrane potential, and promoting apoptosis. Similar results were observed in human granulosa cells after exposure to mono-(2-ethylhexyl) phthalate (MEHP, metabolites of DEHP) in vitro. Proteomic analysis and transmission electron microscopy revealed modifications in the functional proteins and structure of the MAMs, and the suppression of oxidative phosphorylation pathways. The findings of this investigation provide a new perspective on the mechanism underlying the reproductive toxicity of DEHP in females.

Urinary benzophenone-3 concentrations and ovarian reserve in a cohort of subfertile women

OBJECTIVE

To evaluate the association between the urinary benzophenone-3 concentrations and measures of ovarian reserve (OR) among women in the Environment and Reproductive Health study seeking fertility treatment at Massachusetts General Hospital (MGH) in Boston, Massachusetts.

DESIGN

Prospective cohort study.

SETTING

MGH infertility clinic in Boston, Massachusetts.

PATIENT(S)

Women in the Environment and Reproductive Health cohort seeking fertility treatment.

INTERVENTION(S)

Women contributed spot urine samples prior to assessment of OR outcomes that were analyzed for benzophenone-3 concentrations.

MAIN OUTCOME MEASURE(S)

Antral follicle count (AFC) and day 3 follicle-stimulating hormone (FSH) levels were evaluated as part of standard infertility workups during unstimulated menstrual cycles. Quasi-Poisson and linear regression models were used to evaluate the association of the specific gravity-adjusted urinary benzophenone-3 concentrations with AFC and FSH, with adjustment for age and physical activity. In the secondary analyses, models were stratified by age.

RESULT(S)

This study included 142 women (mean age ± standard deviation, 36.1 ± 4.6 years; range, 22-45 years) enrolled between 2009 and 2017 with both urinary benzophenone-3 and AFC measurements and 57 women with benzophenone-3 and FSH measurements. Most women were White (78%) and highly educated (49% with a graduate degree). Women contributed a mean of 2.7 urine samples (range, 1-10), with 37% contributing ≥2 samples. Benzophenone-3 was detected in 98% of samples. The geometric mean specific gravity-corrected urinary benzophenone-3 concentration was 85.9 μg/L (geometric standard deviation, 6.2). There were no associations of benzophenone-3 with AFC and day 3 FSH in the full cohort. In stratified models, a 1-unit increase in the log geometric mean benzophenone-3 concentration was associated with a 0.91 (95% confidence interval, 0.86-0.97) times lower AFC among women aged ≤35 years and an increase in the FSH concentration of 0.73 (95% confidence interval, 0.12-1.34) IU/L among women aged >35 years.

CONCLUSION(S)

In the main models, urinary benzophenone-3 was not associated with OR. However, younger patients may be vulnerable to the potential effects of benzophenone-3 on AFC. Further research is warranted.

The associations between pre-conception urinary phthalate concentrations, the serum metabolome, and live birth among women undergoing assisted reproduction

BACKGROUND

Phthalates are ubiquitous endocrine disruptors. Past studies have shown an association between higher preconception urinary concentrations of phthalate metabolites and lower fertility in women; however, the biological mechanisms remain unclear. Our exploratory study aimed to understand the metabolites and pathways associated with maternal preconception phthalate exposure and examine if any may underline the association between phthalate exposure and live birth using untargeted metabolomics.

METHODS

Participants (n = 183) were part of the Environment and Reproductive Health (EARTH) study, a prospective cohort that followed women undergoing in vitro fertilization (IVF) at the Massachusetts General Hospital Fertility Center (2005-2016). On the same day, women provided a serum sample during controlled ovarian stimulation, which was analyzed for metabolomics using liquid chromatography coupled with high-resolution mass spectrometry and two chromatography columns, and a urine sample, which was analyzed for 11 phthalate metabolites using targeted approaches. We used multivariable generalized linear models to identified metabolic features associated with urinary phthalate metabolite concentrations and live birth, followed by enriched pathway analysis. We then used a meet-in-the-middle approach to identify overlapping pathways and features.

RESULTS

Metabolic pathway enrichment analysis revealed 43 pathways in the C18 negative and 32 pathways in the HILIC positive columns that were significantly associated (p < 0.05) with at least one of the 11 urinary phthalate metabolites or molar sum of di-2-ethylhexyl phthalate metabolites. Lipid, amino acid, and carbohydrate metabolism were the most common pathways associated with phthalate exposure. Five pathways, tryptophan metabolism, tyrosine metabolism, biopterin metabolism, carnitine shuttle, and vitamin B6 metabolism, were also identified as being associated with at least one phthalate metabolite and live birth following IVF.

CONCLUSION

Our study provides further insight into the metabolites and metabolomics pathways, including amino acid, lipid, and vitamin metabolism that may underlie the observed associations between phthalate exposures and lower fertility in women.

Phthalate exposure and subfecundity in preconception couples: A nested case-control study

BACKGROUND

Phthalates (PAEs) are endocrine-disrupting chemicals ubiquitously found in the environment. This study aimed to examine the association between exposure of PAEs and subfecundity in preconception couples.

METHODS

This is a nested case-control study based on preconception cohort. Preconception couples with intention to conceive were enrolled and followed up until a clinically confirmed pregnancy or 12 menstrual cycles of preparation for conception. A total of 107 couples with subfecundity- time to pregnancy (TTP) more than 12 menstrual cycles, and 144 couples ≤12 cycles were included in the analysis. The levels of PAE metabolites in one spot urine samples were detected and compared between the groups. The weighted quantile sum (WQS) regression model and Bayesian kernel machine regression (BKMR) model were used to examine the joint effects of couples' exposure to PAEs on subfecundity.

RESULTS

Using the multivariate binary logistic regression model, compared to the lowest quartile of urinary ∑PAEs concentration group, both preconception females (aOR=2.42, 95% CI: 1.10-5.30, p=0.027) and males (aOR=2.99, 95% CI: 1.36-6.58, p=0.006) in the highest quartile group had an increased risk of subfecundity, and a dose-response relationship was observed between PAEs and the risk of subfecundity. The WQS analyses found that co-exposure to PAE mixture was a risk factor for subfecundity in preconception female (aOR=1.76, 95% CI: 1.38-2.26, p<0.001), male (aOR=1.58, 95% CI: 1.20-2.08, p=0.001), and couple (aOR=2.39, 95% CI: 1.61-3.52, p<0.001). The BKMR model found a positive combined effect of mixed exposure to PAEs on the risk of subfecundity.

CONCLUSIONS

PAEs increase the risk of subfecundity in preconception couples. Our research reinforced the need of monitoring PAE exposure for the purpose of improving human reproductive health.

Phthalate and DINCH exposure and ovarian reserve markers among women seeking infertility care

Phthalate exposure can adversely impact ovarian reserve, yet investigation on the influence of its alternative substance, the non-phthalate plasticizer diisononyl-cyclohexane-1,2-dicarboxylate (DINCH), on ovarian reserve is very sparce. We aimed to investigate the associations of phthalate and DINCH exposure as well as their combined mixture with ovarian reserve. This present study included 657 women seeking infertility care in Jiangsu, China (2015-2018). Urine samples during enrollment prior to infertility treatment were analyzed using high-performance liquid chromatography-isotope dilution tandem mass spectrometry (UPLC-MS/MS) to quantify 17 phthalate metabolites and 3 DINCH metabolites. Multivariate linear regression models, Poisson regression models and weighted quantile sum (WQS) regression were performed to access the associations of 17 urinary phthalate metabolites and 3 DINCH metabolites with ovarian reserve markers, including antral follicle count (AFC), anti-Mullerian hormone (AMH), and follicle-stimulating hormone (FSH). We found that the most conventional phthalates metabolites (DMP, DnBP, DiBP, DBP and DEHP) were inversely associated with AFC, and the DINCH metabolites were positively associated with serum FSH levels. The WQS index of phthalate and DINCH mixtures was inversely associated with AFC (% change = -8.56, 95 % CI: -12.63, -4.31) and positively associated with FSH levels (% change =7.71, 95 % CI: 0.21, 15.78). Our findings suggest that exposure to environmental levels of phthalate and DINCH mixtures is inversely associated with ovarian reserve.

Exposure to the phthalate metabolite MEHP impacts survival and growth of human ovarian follicles in vitro

Phthalates are found in everyday items like plastics and personal care products. There is an increasing concern that continuous exposure can adversely affect female fertility. However, experimental data are lacking to establish causal links between exposure and disease in humans. To address this gap, we tested the effects of a common phthalate metabolite, mono-(2-ethylhexyl) phthalate (MEHP), on adult human ovaries in vitro using an epidemiologically determined human-relevant concentration range (2.05 nM - 20.51 mM). Histomorphological assessments, steroid and cytokine measurements were performed on human ovarian tissue exposed to MEHP for 7 days in vitro. Cell viability and gene expression profile were investigated following 7 days of MEHP exposure using the human granulosa cancer cell lines KGN, and COV434, the germline tumor cell line PA-1, and human ovarian primary cells. Selected differentially expressed genes (DEGs) were validated by RT-qPCR and immunofluorescence in human ovarian tissue. MEHP exposure reduced follicular growth (20.51 nM) and increased follicular degeneration (20.51 mM) in ovarian tissue, while not affecting steroid and cytokine production. Out of the 691 unique DEGs identified across all the cell types and concentrations, CSRP2 involved in cytoskeleton organization and YWHAE as well as CTNNB1 involved in the Hippo pathway, were chosen for further validation. CSRP2 was upregulated and CTNNB1 downregulated in both ovarian tissue and cells, whereas YWHAE was downregulated in cells only. In summary, one-week MEHP exposure of human ovarian tissue can perturb the development and survival of human follicles through mechanisms likely involving dysregulation of cytoskeleton organization and Hippo pathway.

The impact of follicular fluid phthalate metabolites on the ovarian reserve and ovarian function in Indian women undergoing intracytoplasmic sperm injection

OBJECTIVE

To investigate the adverse effects of phthalate-induced ovarian toxicity on the ovarian reserve and ovarian function. To assess whether the accumulation of higher levels of selected phthalate metabolites in the follicular fluid (FF) of Indian women undergoing intracytoplasmic sperm injection (ICSI) was associated with a decline in their antral follicle count (AFC) and/or serum antimüllerian hormone (AMH) levels, suggesting a negative impact on the ovarian reserve. To evaluate the effects of follicular phthalate metabolites on peak serum estradiol (E2) levels and the total number of oocytes and mature metaphase II (MII) stage oocytes retrieved to assess the impact of phthalate toxicity on ovarian function.

DESIGN

A subanalysis of an ongoing prospective cohort study was conducted to examine the association between the levels of six phthalate metabolites, namely, mono-n-butyl phthalate (MBP), mono-ethyl phthalate (MEP), mono-isononyl phthalate (MiNP), mono-isodecyl phthalate (MiDP), mono(2-ethyl-5-oxohexyl) phthalate, and mono(2-ethyl-5-hydroxyhexyl) phthalate, in the FF of Indian women undergoing ICSI and their ovarian reserve markers (AFC and serum AMH levels). To investigate the association of these follicular phthalate metabolite levels with the peak E2 levels and the total number of oocytes and number of MII stage oocytes retrieved.

SETTING

In vitro fertilization center in a referral hospital in India.

PATIENT(S)

A total of 245 consenting Indian women who had undergone oocyte retrieval between April 2017 and mid-March 2020 were included. Each woman contributed one FF sample to the study. This was screened for six phthalate metabolites. The samples were collected before the coronavirus disease 2019 pandemic.

INTERVENTION(S)

Using liquid chromatography-tandem mass spectrometry, the total levels of six phthalate metabolites were quantified in the FF of 245 women. Using linear regression models that were unadjusted and adjusted for maternal age and body mass index (BMI), we evaluated the association between the follicular metabolites in these women and their AFC, serum AMH levels, peak E2 levels, total number of oocytes, and MII stage oocytes.

MAIN OUTCOME MEASURE(S)

To evaluate the impact of phthalate-induced ovarian toxicity on the ovarian reserve and ovarian function in Indian women undergoing ICSI by studying their accumulated levels in their FF.

RESULT(S)

For MiNP (a metabolite of di-isononyl phthalate), in linear regression models adjusted for age and BMI, we found that with increasing quartiles of follicular MiNP, there was a significant trend in the decrease in mean AFC (P-trend = 0.023) and a suggestive trend in the decrease in mean serum AMH levels (P-trend = 0.077). For MiDP (a metabolite of di-isodecyl phthalate), in the unadjusted regression model, we found that with increasing quartiles of follicular MiDP, there was a significant trend in the decrease in mean serum AMH levels (P-trend = 0.045). For MBP (a metabolite of dibutyl phthalate), in linear regression models adjusted for age and BMI, we found that with increasing quartiles of follicular MBP, there were significant trends in the decrease in the mean number of total oocytes retrieved (P-trend = 0.003), a decrease in the mean number of MII stage oocytes retrieved, (P-trend = 0.003) and a decrease in the mean peak E2 levels (P-trend = 0.016). Although we found that with increasing quartiles of follicular mono(2-ethyl-5-oxohexyl) phthalate there was a decrease in the mean number of total and MII stage oocytes retrieved and higher follicular MEP levels were negatively associated with the mean AFC and serum AMH levels, neither trend was statistically significant. We also found that although follicular MEP levels did not show an adverse impact on ovarian function, follicular mono(2-ethyl-5-hydroxyhexyl) phthalate levels did not show an adverse impact on both the ovarian reserve and function.

CONCLUSION

In this study of 245 Indian women, higher accumulated FF levels of MiNP and MiDP were negatively associated with AFC and serum AMH levels, suggesting an adverse effect on the ovarian reserve. Higher accumulated FF levels of MBP were negatively associated with the total number of oocytes, MII stage oocytes, and peak E2 values, suggesting a negative impact on ovarian function. Although we found that phthalate-induced ovarian toxicity was statistically significant for selected phthalate metabolites, the role of the cumulative effect of multiple phthalates in the ovarian microenvironment cannot be ruled out and needs to be investigated further.

Mechanisms of imbalanced testicular homeostasis in infancy due to aberrant histone acetylation in undifferentiated spermatogonia under different concentrations of Di(2-ethylhexyl) phthalate (DEHP) exposure

Di (2-ethylhexyl) phthalate (DEHP), identified as an endocrine-disrupting chemical, is associated with reproductive toxicity. This association is particularly noteworthy in newborns with incompletely developed metabolic functions, as exposure to DEHP can induce enduring damage to the reproductive system, potentially influencing adult reproductive health. In this study, we continuously administered 40 μg/kg and 80 μg/kg DEHP to postnatal day 5 (PD5) mice for ten days to simulate low and high doses of DEHP exposure during infancy. Utilizing single-cell RNA sequencing (scRNA-seq), our analysis revealed that varying concentrations of DEHP exposure during infancy induced distinct DNA damage response characteristics in testicular Undifferentiated spermatogonia (Undiff SPG). Specifically, DNA damage triggered mitochondrial dysfunction, leading to acetyl-CoA content alterations. Subsequently, this disruption caused aberrations in histone acetylation patterns, ultimately resulting in apoptosis of Undiff SPG in the 40 μg/kg DEHP group and autophagy in the 80 μg/kg DEHP group. Furthermore, we found that DEHP exposure impacts the development and functionality of Sertoli and Leydig cells through the focal adhesion and PPAR signaling pathways, respectively. We also revealed that Leydig cells regulate the metabolic environment of Undiff SPG via Ptn-Sdc4 and Mdk-Sdc4 after DEHP exposure. Finally, our study provided pioneering evidence that disruptions in testicular homeostasis induced by DEHP exposure during infancy endure into adulthood. In summary, this study elucidates the molecular mechanisms through which DEHP exposure during infancy influences the development of testicular cell populations.

Phthalates are detected in the follicular fluid of adolescents and oocyte donors with associated changes in the cumulus cell transcriptome

Purpose

To investigate follicular fluid (FF) phthalate levels in adolescents undergoing fertility preservation compared to oocyte donors and explore its association with ovarian reserve and cumulus cell gene expression.

Methods

20 Adolescents (16.7 ± 0.6 years old) and 24 oocyte donors (26.2 ± 0.4 years old) undergoing fertility preservation were included in the study. Patient demographics, ovarian stimulation and oocyte retrieval outcomes were analyzed for each group. FF levels of 9 phthalate metabolites were assessed individually and as molar sums representative of common compounds (all phthalates: ΣPhthalates; DEHP: ΣDEHP), exposure sources (plastics: ΣPlastic; personal care products: ΣPCP), and modes of action (anti-androgenic: ΣAA) and compared between the two groups.

Results

Follicular fluid ΣPlastic and ΣPCP levels were significantly higher in adolescents compared to oocyte donors (p<0.05). Follicular fluid ΣDEHP, ΣPlastic, ΣPCP, ΣAA, and ΣPhthalates levels were positively associated with antral follicle count (AFC) (p<0.05) in oocyte donors when adjusted for age, BMI, and race/ethnicity. RNA-seq analysis revealed 248 differentially expressed genes (DEGs) in cumulus cells of adolescents within the top quartile (n=4) of FF ΣPhthalates levels compared to the adolescents within the bottom half (n=9). Genes enriched in pathways involved in cell motility and development were significantly downregulated.

Conclusion

Adolescents undergoing fertility preservation cycles demonstrate higher levels of phthalate metabolites in their follicular fluid compared to oocyte donors. Phthalate metabolite levels in FF are associated with higher AFC levels in oocyte donors. Higher phthalate levels in FF are associated with alterations in the cumulus cells transcriptome in adolescents.

Advances in understanding the reproductive toxicity of endocrine-disrupting chemicals in women

Recently, there has been a noticeable increase in disorders of the female reproductive system, accompanied by a rise in adverse pregnancy outcomes. This trend is increasingly being linked to environmental pollution, particularly through the lens of Endocrine Disrupting Chemicals (EDCs). These external agents disrupt natural processes of hormones, including synthesis, metabolism, secretion, transport, binding, as well as elimination. These disruptions can significantly impair human reproductive functions. A wealth of animal studies and epidemiological research indicates that exposure to toxic environmental factors can interfere with the endocrine system's normal functioning, resulting in negative reproductive outcomes. However, the mechanisms of these adverse effects are largely unknown. This work reviews the reproductive toxicity of five major environmental EDCs-Bisphenol A (BPA), Phthalates (PAEs), Triclocarban Triclosan and Disinfection Byproducts (DBPs)-to lay a foundational theoretical basis for further toxicological study of EDCs. Additionally, it aims to spark advancements in the prevention and treatment of female reproductive toxicity caused by these chemicals.

Comparative analysis of diisononyl phthalate and di(isononyl)cyclohexane-1,2 dicarboxylate plasticizers in regulation of lipid metabolism in 3T3-L1 cells

Diisononyl phthalate (DINP) and di(isononyl)cyclohexane-1,2-dicarboxylate (DINCH) are plasticizers introduced to replace previously used phthalate plasticizers in polymeric products. Exposure to DINP and DINCH has been shown to impact lipid metabolism. However, there are limited studies that address the mechanisms of toxicity of these two plasticizers. Here, a comparative toxicity analysis has been performed to evaluate the impacts of DINP and DINCH on 3T3-L1 cells. The preadipocyte 3T3-L1 cells were exposed to 1, 10, and 100 μM of DINP or DINCH for 10 days and assessed for lipid accumulation, gene expression, and protein analysis. Lipid staining showed that higher concentrations of DINP and DINCH can induce adipogenesis. The gene expression analysis demonstrated that both DINP and DINCH could alter the expression of lipid-related genes involved in adipogenesis. DINP and DINCH upregulated Pparγ, Pparα, C/EBPα Fabp4, and Fabp5, while both compounds significantly downregulated Fasn and Gata2. Protein analysis showed that both DINP and DINCH repressed the expression of FASN. Additionally, we analyzed an independent transcriptome dataset encompassing temporal data on lipid differentiation within 3T3-L1 cells. Subsequently, we derived a gene set that accurately portrays significant pathways involved in lipid differentiation, which we subsequently subjected to experimental validation through quantitative polymerase chain reaction. In addition, we extended our analysis to encompass a thorough assessment of the expression profiles of this identical gene set across 40 discrete transcriptome datasets that have linked to diverse pathological conditions to foreseen any potential association with DINP and DINCH exposure. Comparative analysis indicated that DINP could be more effective in regulating lipid metabolism.

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.

Endocrine disruptors: Unravelling the link between chemical exposure and Women's reproductive health

An Endocrine Disrupting Chemical (EDC) is any compound that disrupts the function of the endocrine system in humans and is ubiquitous in the environment either as a result of natural events or through anthropogenic activities. Bisphenol A, phthalates, parabens, pesticides, triclosan, polychlorinated biphenyls, and heavy metals, which are frequently found in the pharmaceutical, cosmetic, and packaging sectors, are some of the major sources of EDC pollutants. EDCs have been identified to have a deteriorating effect on the female reproductive system, as evidenced by the increasing number of reproductive disorders such as endometriosis, uterine fibroids, polycystic ovary syndrome, premature ovarian failure, menstrual irregularity, menarche, and infertility. Studying EDCs in relation to women's health is essential for understanding the complex interactions between environmental factors and health outcomes. It enables the development of strategies to mitigate risks, protect reproductive and overall health, and inform public policy decisions to safeguard women's well-being. Healthcare professionals must know the possible dangers of EDC exposure and ask about environmental exposures while evaluating patients. This may result in more precise diagnosis and personalized treatment regimens. This review summarises the existing understanding of prevalent EDCs that impact women's health and involvement in female reproductive dysfunction and underscores the need for more research. Further insights on potential mechanisms of action of EDCs on female has been emphasized in the article. We also discuss the role of nutritional intervention in reducing the effect of EDCs on women's reproductive health. EDC pollution can be further reduced by adhering to strict regulations prohibiting the release of estrogenic substances into the environment.

Associations between urinary phthalate concentrations and antral follicle count among women undergoing in vitro fertilization

Background

Phthalates are ubiquitously used in a variety of products and have an adverse effect on folliculogenesis. However, previous epidemiological studies on the associations between phthalate exposure and antral follicle count (AFC) produced conflicting results. The present study aimed to evaluate the associations between urinary phthalate metabolite concentrations and AFC among women undergoing in vitro fertilization (IVF).

Methods

We collected 525 urine samples and measured 8 phthalate metabolites from IVF patients. Poisson regression models were conducted to evaluate the associations between phthalate metabolite concentrations and AFC. In addition, participants were stratified into a younger group (< 35 years) and an older group (≥ 35 years) to explore the potential effect modification by age. We also performed sensitivity analyses by restricting our analyses to only infertile women diagnosed with tubal factor infertility to test the robustness of the results.

Results

Significant positive associations were observed among urinary MBP, MEOHP and ∑PAEs concentrations and AFC after adjusting for age, BMI, year of study and infertility diagnosis. Compared with women in the first tertile, women in the third tertile of MBP and MEOHP had 7.02% (95% CI: 1.18%, 12.9%) and 8.84% (95% CI: 2.83%, 14.9%) higher AFC, respectively, and women in the second and third tertiles of ∑PAEs had 6.19% (95% CI: 0.37%, 12.0%) and 9.09% (95% CI: 3.22%, 15.0%) higher AFC, respectively. In addition, MBP, MEOHP and ∑PAEs also had significant positive associations with AFC in trend tests for dose-response. In the age-stratified analysis, we found a stronger relationship between phthalate metabolite concentrations and AFC among older women and an inverse association among younger women. We observed similar results in the sensitivity analyses.

Conclusion

We found positive associations between phthalate exposure and AFC, which support the idea that phthalate exposure may accelerate primordial follicle recruitment and lead to higher AFC in women undergoing IVF. More studies are needed to better understand their relationships.

Phthalate metabolites in urine and follicular fluid in relation to menstrual cycle characteristics in women seeking fertility assistance

BACKGROUND

Phthalates have been shown to disrupt the estrous cycle in animal studies. However, epidemiological research investigating their associations with menstrual cycle characteristics is limited.

OBJECTIVE

To explore the relationships between phthalate exposure and menstrual cycle characteristics among women seeking fertility assistance.

METHODS

We determined the levels of eight phthalate metabolites in both follicular fluid (FF) and urine specimens collected from 441 women in the Tongji Reproductive and Environmental (TREE) cohort, using high-performance liquid chromatography and tandem mass spectrometry. Information about menstrual cycle parameters was obtained through a questionnaire. The impacts of individual and joint exposure to phthalates on menstrual cycle characteristics were assessed using multivariable linear regression, Poisson regression, and quantile g-computation approaches.

RESULTS

After adjusting for relevant covariates, we found that per log10-unit increase in mono(2-ethylhexyl) phthalate (MEHP) level in urine specimens was associated with a decrease of 0.20 days (95 % CI: -0.37, -0.03) in bleeding duration. We also observed that mono(2-ethyl-5-carboxypentyl) phthalate (MECPP) and the sum of di(2-ethylhexyl) phthalate (DEHP) metabolites (∑DEHP) concentrations in FF samples were inversely related to cycle length [β = -1.92 (95 % CI: -3.10, -0.75) and -1.87 (95 % CI: -3.56, -0.19), respectively]. However, we generally observed null associations between phthalate metabolites and irregular cycle, dysmenorrhea, hypomenorrhea, or cycle length variation. Furthermore, we also found that phthalate metabolite mixtures in FF and urine were generally unrelated to menstrual cycle characteristics.

CONCLUSION

Our findings suggest that some DEHP metabolites in FF and urine are inversely associated with menstrual cycle length and menstrual bleeding duration in women attending a fertility center.

The influence of environmental factors on premature ovarian insufficiency and ovarian aging

Premature ovarian insufficiency and ovarian aging are complex conditions that affect women's reproductive health and overall well-being. They are both characterized by hypergonadotropic hypogonadism and infertility, and together affect about 1 in 100 women by the age of 40. This review explores the influence of environmental factors on the development and progression of premature ovarian insufficiency and ovarian aging. When referring to environmental factors, we include a wide range of external agents and conditions, including chemicals, socioeconomic factors and lifestyle choices. Through a review of the literature, we attempt to highlight the link between environmental factors and ovarian health. We examine the impact of endocrine-disrupting chemicals, such as bisphenol A and phthalates, on ovarian function and investigate the mechanisms by which these chemicals can disrupt hormone signaling pathways, leading to alterations in ovarian reserve, oocyte quality, and folliculogenesis. Moreover, we explore lifestyle factors like obesity, stress, smoking and alcohol in relation to their effects on ovarian aging. Epigenetic changes may play a crucial role in the prevalence of premature ovarian insufficiency. Understanding the impact of environmental factors on premature ovarian insufficiency and ovarian aging is very important in public and clinical health contexts. By identifying risk factors, healthcare providers can develop targeted and strategic prevention and intervention plans. Furthermore, this knowledge can promote reproductive health and minimize exposure to harmful environmental agents.

Ovarian follicular fluid levels of phthalates and benzophenones in relation to fertility outcomes

BACKGROUND

Many endocrine disrupting chemicals (EDCs), for instance phthalates and benzophenones, are associated with adverse fertility outcomes and semen quality parameters.

OBJECTIVE

To evaluate if concentrations of selected phthalate metabolites and benzophenones measured in follicular fluid are associated with fertility outcomes (i.e., reproductive hormones, antral follicle count, detected heartbeat at gestational week 7, and live birth) and, in a supplementary study, if measured concentrations of chemicals in follicular fluid can exert biological effects on human spermatozoa.

METHODS

Overall, 111 couples from a fertility clinic in Denmark contributed with 155 follicular fluid samples. Concentrations of 43 metabolites from 19 phthalates and phthalate substitutes and six benzophenones were measured in follicular fluid using liquid chromatography-tandem mass spectrometry. Multiple linear and logistic regression with an applied generalized estimating equation model allowing more than one measurement per woman assessed the association between follicular EDC levels and fertility outcomes. The assessment of biological effects of individual and mixtures of EDCs on human spermatozoa was conducted through a human sperm cell based Ca2+-fluorimetric assay.

RESULTS

Benzophenone-3 (BP-3) and seven metabolites of five phthalates were detectable in follicular fluid. Women with metabolites of dibutyl phthalate isomers in the highest tertiles had lower antral follicle count (MiBP: β = -5.35 [95 % CI: -9.06; -2.00], MnBP: β = -5.25 [95 % CI: -9.00; -2.00]) and lower odds for detecting a heartbeat at gestational week 7 (MiBP: OR = 0.35 [95 % CI: 0.14; 0.91], MnBP: OR = 0.39 [95 % CI: 0.13; 1.15]). Mixtures of the measured concentrations of BP-3 and the seven phthalate metabolites induced a small significant increase in the intracellular calcium ion concentration in human spermatozoa from healthy donors (n = 3).

DISCUSSION

Phthalate metabolites and BP-3 were detectable in follicular fluid and high concentrations of some phthalate metabolites were linked with lower chance of successful fertility treatment outcomes. Chemical mixture concentrations in follicular fluid induced a calcium response in human spermatozoa highlighting possible biological effects at physiologically relevant concentrations.

Associations between Phthalate Metabolite Concentrations in Follicular Fluid and Reproductive Outcomes among Women Undergoing in Vitro Fertilization/Intracytoplasmic Sperm Injection Treatment

BACKGROUND

Phthalates have been reported to impair fertility in various studies. However, evidence exploring the associations between phthalate metabolites in follicular fluid (FF) and reproductive outcomes is lacking.

OBJECTIVES

To investigate the associations between phthalate metabolite concentrations in FF and in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) outcomes among women recruited from a fertility clinic.

METHODS

We included 641 women undergoing IVF/ICSI treatment from December 2018 to January 2020. The levels of eight phthalate metabolites, including monoethyl phthalate (MEP), mono-isobutyl phthalate (MiBP), mono-n -butyl phthalate (MBP), monobenzyl phthalate (MBzP), mono(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), and mono(2-ethyl-5-carboxypentyl) phthalate (MECPP), were quantified in FF collected on the oocyte retrieval day. Associations between quartiles of individual phthalate metabolite concentrations and nine IVF/ICSI outcomes, including oocyte yield, mature oocyte number, two distinct pronuclei (2PN) zygote number, fertilization rate, blastocyst formation rate, implantation, clinical pregnancy, miscarriage, and live birth, were estimated with generalized linear models. The effects of phthalate mixtures on IVF/ICSI outcomes were assessed using Bayesian kernel machine regression (BKMR) models.

RESULTS

After adjusting for relevant confounders, elevated quartiles of MBzP, MEHHP, and MEHP in FF were inversely associated with the numbers of retrieved oocytes, mature oocytes, and 2PN zygotes (all p for trends < 0.10 ). In comparison with the lowest quartile, the highest quartile of molar sum of di(2-ethylhexyl) phthalate metabolites (Σ DEHP ) was associated with a reduction of 9.1% [95% confidence interval (CI): - 17.1 % , - 0.37 % ] and 10.3% (95% CI: - 18.8 % , - 0.94 % ) in yielded oocyte and mature oocyte numbers, respectively. Furthermore, the BKMR models revealed inverse associations between phthalate mixtures and the numbers of retrieved oocytes and mature oocytes. We generally found null results for implantation, clinical pregnancy, miscarriage, and live birth.

DISCUSSION

Certain phthalate metabolites in FF are inversely associated with the numbers of retrieved oocytes, mature oocytes, and 2PN zygotes among women undergoing IVF/ICSI treatment. https://doi.org/10.1289/EHP11998.

Mixtures of urinary concentrations of phenols and phthalate biomarkers in relation to the ovarian reserve among women attending a fertility clinic

Although prior studies have found associations of the ovarian reserve with urinary concentrations of some individual phenols and phthalate metabolites, little is known about the potential associations of these chemicals as a mixture with the ovarian reserve. We investigated whether mixtures of four urinary phenols (bisphenol A, butylparaben, methylparaben, propylparaben) and eight metabolites of five phthalate diesters including di(2-ethylhexyl) phthalate were associated with markers of the ovarian reserve among 271 women attending a fertility center who enrolled in the Environment and Reproductive Health study (2004-2017). The analysis was restricted to one outcome per study participant using the earliest outcome after the last exposure assessment. Ovarian reserve markers included lower antral follicle count (AFC) defined as AFC < 7, circulating serum levels of day 3 follicle stimulating hormone (FSH) assessed by immunoassays, and diminished ovarian reserve (DOR) defined as either AFC < 7, FSH > 10 UI/L or primary infertility diagnosis of DOR. We applied Bayesian Kernel Machine Regression (BKMR) and quantile g-computation to estimate the joint associations and assess the interactions between chemical exposure biomarkers on the markers of the ovarian reserve while adjusting for confounders. Among all 271 women, 738 urine samples were collected. In quantile g-computation models, a quartile increase in the exposure biomarkers mixture was not significantly associated with lower AFC (OR = 1.10, 95 % CI = 0.52, 2.30), day 3 FSH levels (Beta = 0.30, 95 % CI = -0.32, 0.93) or DOR (OR = 1.02, 95 % CI = 0.52, 2.05). Similarly, BKMR did not show any evidence of associations between the mixture and any of the studied outcomes, or interactions between chemicals. Despite the lack of associations, these results need to be explored among women in other study cohorts.

A vision for safer food contact materials: Public health concerns as drivers for improved testing

Food contact materials (FCMs) and food contact articles are ubiquitous in today's globalized food system. Chemicals migrate from FCMs into foodstuffs, so called food contact chemicals (FCCs), but current regulatory requirements do not sufficiently protect public health from hazardous FCCs because only individual substances used to make FCMs are tested and mostly only for genotoxicity while endocrine disruption and other hazard properties are disregarded. Indeed, FCMs are a known source of a wide range of hazardous chemicals, and they likely contribute to highly prevalent non-communicable diseases. FCMs can also include non-intentionally added substances (NIAS), which often are unknown and therefore not subject to risk assessment. To address these important shortcomings, we outline how the safety of FCMs may be improved by (1) testing the overall migrate, including (unknown) NIAS, of finished food contact articles, and (2) expanding toxicological testing beyond genotoxicity to multiple endpoints associated with non-communicable diseases relevant to human health. To identify mechanistic endpoints for testing, we group chronic health outcomes associated with chemical exposure into Six Clusters of Disease (SCOD) and we propose that finished food contact articles should be tested for their impacts on these SCOD. Research should focus on developing robust, relevant, and sensitive in-vitro assays based on mechanistic information linked to the SCOD, e.g., through Adverse Outcome Pathways (AOPs) or Key Characteristics of Toxicants. Implementing this vision will improve prevention of chronic diseases that are associated with hazardous chemical exposures, including from FCMs.

Human-relevant exposure to di-n-butyl phthalate tampers with the ovarian insulin-like growth factor 1 system and disrupts folliculogenesis in young adult mice

Phthalates are compounds used in consumer and medical products worldwide. Phthalate exposure in women has been demonstrated by detection of phthalate metabolites in their urine and ovarian follicular fluid. High urinary phthalate burden has been associated with reduced ovarian reserve and oocyte retrieval in women undergoing assisted reproduction. Unfortunately, no mechanistic explanation for these associations is available. In short term in vivo and in vitro animal studies modeling human-relevant exposures to di-n-butyl phthalate (DBP), we have identified ovarian folliculogenesis as a target for phthalate exposures. In the present study, we investigated whether DBP exposure negatively influences insulin-like growth factor 1 (IGF1) signaling in the ovary and disrupts ovarian folliculogenesis. CD-1 female mice were exposed to corn oil (vehicle) or DBP (10 µg/kg/day, 100 µg/kg/day, or 1000 mg/kg/day) for 20-32 days. Ovaries were collected as animals reached the proestrus stage to achieve estrous cycle synchronization. Levels of mRNAs encoding IGF1 and 2 (Igf1 and Igf2), IGF1 receptor (Igf1r), and IGF-binding proteins 1-6 (Ifgbp1-6) were measured in whole ovary homogenates. Ovarian follicle counts and immunostaining for phosphorylated IGF1R protein (pIGF1R) were used to evaluate folliculogenesis and IGF1R activation, respectively. DBP exposure, at a realistic dose that some women may experience (100 µg/kg/day for 20-32 days), reduced ovarian Igf1 and Igf1r mRNA expression and reduced small ovarian follicle numbers and primary follicle pIGF1R positivity in DBP-treated mice. These findings reveal that DBP tampers with the ovarian IGF1 system and provide molecular insight into how phthalates could influence the ovarian reserve in females.

Identification of phthalate mixture exposure targets in the human and mouse ovary in vitro

Chemical health risk assessment is based on single chemicals, but humans and wildlife are exposed to extensive mixtures of industrial substances and pharmaceuticals. Such exposures are life-long and correlate with multiple morbidities, including infertility. How combinatorial effects of chemicals should be handled in hazard characterization and risk assessment are open questions. Further, test systems are missing for several relevant health outcomes including reproductive health and fertility in women. Here, our aim was to screen multiple ovarian cell models for phthalate induced effects to identify biomarkers of exposure. We used an epidemiological cohort study to define different phthalate mixtures for in vitro testing. The mixtures were then tested in five cell models representing ovarian granulosa or stromal cells, namely COV434, KGN, primary human granulosa cells, primary mouse granulosa cells, and primary human ovarian stromal cells. Exposures at epidemiologically relevant levels did not markedly elicit cytotoxicity or affect steroidogenesis in short 24-hour exposure. However, significant effects on gene expression were identified by RNA-sequencing. Altogether, the exposures changed the expression of 124 genes on the average (9-479 genes per exposure) in human cell models, without obvious concentration or mixture-dependent effects on gene numbers. The mixtures stimulated distinct changes in different cell models. Despite differences, our analyses suggest commonalities in responses towards phthalates, which forms a starting point for follow-up studies on identification and validation of candidate biomarkers that could be developed to novel assays for regulatory testing or even into clinical tests.

Use of Chemical Hair Straighteners and Fecundability in a North American Preconception Cohort

Chemical hair straighteners ("relaxers") are used by millions of North Americans, particularly women of color. Hair relaxers may contain endocrine-disrupting compounds, which can harm fertility. We evaluated the association between hair relaxer use and fecundability among 11,274 participants from Pregnancy Study Online (PRESTO), a North American preconception cohort study. During 2014-2022, participants completed a baseline questionnaire in which they reported their history of relaxer use and completed follow-up questionnaires every 8 weeks for 12 months or until pregnancy, whichever came first. We used multivariable-adjusted proportional probabilities regression models to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs). Relative to never use, fecundability was lower among current (FR = 0.81, 95% CI: 0.64, 1.03) and former (FR = 0.89, 95% CI: 0.81, 0.98) users of hair relaxers. FRs for first use of hair relaxers at ages <10, 10-19, and ≥20 years were 0.73 (95% CI: 0.55, 0.96), 0.93 (95% CI: 0.83, 1.04), and 0.85 (95% CI: 0.74, 0.98), respectively. Fecundability was lowest among those with longer durations of use (≥10 years vs. never: FR = 0.71, 95% CI: 0.54, 0.91) and more frequent use (≥5 times/year vs. never: FR = 0.82, 95% CI: 0.60, 1.11), but associations were nonmonotonic. In this preconception cohort study, use of chemical hair straighteners was associated with slightly reduced fecundability.

Exposure to perfluoroalkyl substances and women's fertility outcomes in a Singaporean population-based preconception cohort

OBJECTIVES

Experimental models have demonstrated a link between exposure to perfluoroalkyl substances (PFAS) and decreased fertility and fecundability; however, human studies are scarce. We assessed the associations between preconception plasma PFAS concentrations and fertility outcomes in women.

METHODS

In a case-control study nested within the population-based Singapore Preconception Study of Long-Term Maternal and Child Outcomes (S-PRESTO), we measured PFAS in plasma collected in 2015-2017 from 382 women of reproductive age trying to conceive. Using Cox proportional hazards regression (fecundability ratios [FRs]) and logistic regression (odds ratios [ORs]) models, we assessed the associations of individual PFAS with time-to-pregnancy (TTP), and the likelihoods of clinical pregnancy and live birth, respectively, over one year of follow-up, adjusting for analytical batch, age, education, ethnicity, and parity. We used Bayesian weighted quantile sum (BWQS) regression to assess the associations of the PFAS mixture with fertility outcomes.

RESULTS

We found a 5-10 % reduction in fecundability per quartile increase of exposure to individual PFAS (FRs [95 % CIs] for clinical pregnancy = 0.90 [0.82, 0.98] for PFDA; 0.88 [0.79, 0.99] for PFOS; 0.95 [0.86, 1.06] for PFOA; 0.92 [0.84, 1.00] for PFHpA). We observed similar decreased odds of clinical pregnancy (ORs [95 % CIs] = 0.74 [0.56, 0.98] for PFDA; 0.76 [0.53, 1.09] for PFOS; 0.83 [0.59, 1.17] for PFOA; 0.92 [0.70, 1.22] for PFHpA) and live birth per quartile increases of individual PFAS and the PFAS mixture (ORs [95 % CIs] = 0.61 [0.37, 1.02] for clinical pregnancy, and 0.66 [0.40, 1.07] for live birth). Within the PFAS mixture, PFDA followed by PFOS, PFOA, and PFHpA were the biggest contributors to these associations. We found no evidence of association for PFHxS, PFNA, and PFHpS and the fertility outcomes examined.

CONCLUSIONS

Higher PFAS exposures may be associated with decreased fertility in women. The potential impact of ubiquitous PFAS exposures on infertility mechanisms requires further investigation.

Dysregulation of steroid metabolome in follicular fluid links phthalate exposure to diminished ovarian reserve of childbearing-age women

The widespread use of phthalates (PAEs) has drawn increasing attention due to their endocrine disruption and reproductive toxicity, while the steroid metabolome is essential for follicular development. However, the mechanism by which PAE exposure affects ovarian reserve through the steroid metabolome remains unclear. This study recruited 264 childbearing-age women in Tianjin (China) from April 2019 to August 2020 in a cross-sectional design. Target metabolome analysis of 16 steroids was performed in follicular fluid (FF) to compare diminished ovarian reserve (DOR) against normal ovarian reserve (NOR) women and differential steroids were identified using binary logistic analyses. Further analysis of eleven PAE metabolites (mPAEs) in FF was conducted, and the retrieved oocyte number (RON) representing ovarian reserve was counted. Multiple linear regression and quantile-based g-computation (qgcomp) models were used to associate individual mPAEs and mPAE mixture with the DOR-related differential steroids in FF. Mediation analysis was used to discuss the mediating effect of DOR-related steroids on the association between mPAEs and RON. Androstenedione (A4), corticosterone (CORT), cortisol (COR) and cortisone were significantly down-regulated in FF from women with DOR. Nine mPAEs with detection frequencies greater than 60% and median concentrations of 0.02-4.86 ng/mL were incorporated into statistical models. Negative associations with COR and CORT were found for mono-ethyl phthalate (mEP), mono-(2-ethyl-5-oxohexyl) phthalate (mEOHP), and mono-2-ethylhexyl phthalate (mEHP). A positive association with cortisone was found for mEOHP, mEHP, monobutyl phthalate (mBP), and mono (2-isobutyl) phthalate (miBP). The qgcomp and mediation analyses revealed that mEP and mEOHP not only significantly contributed to the decline of COR and CORT in the mixed exposure but also indirectly reduced RON through the mediating effects of COR and CORT. In conclusion, PAE exposure may decrease ovarian reserve by downregulating COR and CORT.

Mixed and single effects of endocrine disrupting chemicals in follicular fluid on likelihood of diminished ovarian reserve: A case-control study

Endocrine-disrupting chemicals (EDCs) are a group of the most widely spread pollutants. Their impacts on reproductive health have become public concerns. Diminished ovarian reserve (DOR) is a disorder of ovarian function. Associations between EDC and DOR have been inconsistent. Very little research investigated the joint effects of multiple EDCs. Here, we performed a case-control study among 64 DOR women and 86 controls. Twenty-one EDC chemicals were assessed in follicular fluid, including parabens, phenols, phthalates and poly-fluoroalkyl substances. Both mixed and single effects of EDCs on DOR were evaluated and validated with a Bayesian kernel machine and logistic regressions. We found that the likelihood of DOR significantly increased with rising levels of the 21-EDC mixture, with an odds ratio (OR) and 95% confidence interval (CI) of 2.12 (1.17-3.83) for the 75th percentile compared to its median level. The overall effect was higher than effects of each subgroup. BP4, MECPP, and PFHxA were driving the association to the mixture, and their single effects were validated, with individual ORs of 8.25 (95%CI:3.45-12.21), 1.92 (95%CI:1.02-4.09), and 1.84 (95%CI:1.08-3.86), respectively. In conclusion, we provided new pollutant markers for DOR and emphasized the importance of the effects of EDC mixtures on female reproductive health.

Human relevant exposure to di-n-butyl phthalate tampers with the ovarian insulin-like growth factor 1 system and disrupts folliculogenesis in young adult mice

Phthalates are compounds used in consumer and medical products worldwide. Phthalate exposure in women has been demonstrated by detection of phthalate metabolites in their urine and ovarian follicular fluid. High urinary phthalate burden has been associated with reduced ovarian reserve and oocyte retrieval in women undergoing assisted reproduction. Unfortunately, no mechanistic explanation for these associations is available. In short term in vivo and in vitro animal studies modeling human relevant exposures to di-n-butyl phthalate (DBP), we have identified ovarian folliculogenesis as a target for phthalate exposures. In the present study, we investigated whether DBP exposure negatively influences insulin-like growth factor 1 (IGF) signaling in the ovary and disrupts ovarian folliculogenesis. CD-1 female mice were exposed to corn oil (vehicle) or DBP (10 or 100 μg/kg/day) for 20-32 days. Ovaries were collected as animals reached the proestrus stage to achieve estrous cycle synchronization. Levels of mRNAs encoding IGF1 and 2 ( Igf1 and Igf2 ), IGF1 receptor ( Igf1r ), and IGF binding proteins 1-6 ( Ifgbp1-6 ) were measured in whole ovary homogenates. Ovarian follicle counts and immunostaining for phosphorylated IGF1R protein (pIGF1R) were used to evaluate folliculogenesis and IGF1R activation, respectively. DBP exposure, at a realistic dose that some women may experience (100 μg/kg/day for 20-32 days), reduced ovarian Igf1 and Igf1r mRNA expression and reduced small ovarian follicle numbers and primary follicle pIGF1R positivity in DBP-treated mice. These findings reveal that DBP tampers with the ovarian IGF1 system and provide molecular insight into how phthalates could influence the ovarian reserve in females.

Screening for phthalates biomarkers and its potential role in infertility outcomes in Jordan

BACKGROUND

Phthalates are endocrine disrupting chemicals that are used in plastic and personal care products. Phthalate exposure has been linked to reproductive and fertility outcomes.

OBJECTIVES

This study aimed to assess the phthalate exposures using both urinary level of two DEHP metabolites in females and questionnaires. It also aimed to investigate the association between phthalate levels and reproductive and fertility outcomes.

METHODS

325 females with and without fertility problems at gynaecology clinics filled out a questionnaire and provided a urine sample. Urine samples were analyzed for two DEHP metabolites: MEHHP, mono (2-ethyl-5-hydroxyhexyl) phthalate; MEOHP, mono (2-ethyl-5-oxohexyl) phthalate, using an HPLC/MS/MS analytical method.

RESULTS

We observed a significant difference between cases and controls in terms of heating plastic in the microwave and use of skin and eye make-up, sunscreen, and nail polish. Our findings showed that MEOHP exposure is significantly associated with infertility among Jordanian women (Adjusted OR = 1.66, 95% CI: 1.14, 2.40, p-value = 0.002).

SIGNIFICANCE

To the best of our knowledge, our study is the first of its kind done in Jordan to screen for phthalate exposure and investigate its association with infertility. Our study demonstrated high exposure of the Jordanian population to DEHP. It confirms the association between DEHP exposure and infertility.

IMPACT STATEMENT

We measured phthalates in infertile and fertile women, in a community unaware of phthalate sources or its impacts, and with no regulation limits set. We aimed to increase awareness to environmental exposure to phthalates, emphasize the importance of implementation of public health interventions to control and minimize the effects of phthalate exposure and provide a base for further studies and future research to aid in the formation of policies and guidelines for the manufacturing and use of phthalates.

Environmental factors affecting pregnancy outcomes

INTRODUCTION

Pregnancy represents a fragile period in the life of a woman, vulnerable to hazardous environmental substances which might affect maternal and fetal metabolism. The possible influence of environmental factors, including endocrine disrupting chemicals (EDCs), upon the mother and the fetus before and/or during pregnancy might be associated directly and/or indirectly to deleterious pregnancy outcomes. Because the existence of such associations would be, to our view, of major importance to the scientific community, their investigation is the scope of this critical review.

METHODS

This critical review includes in vivo animal and human studies regarding the role of environmental factors, including EDCs, on pregnancy outcomes complying with the SANRA (a scale for the quality assessment of narrative review articles) questions for narrative reviews. Studies were identified by searching the MEDLINE (PubMed and PubMed Central), the Cochrane library and the Google Scholar databases till October 2022 with the combinations of the appropriate key words (detailed environmental factors including EDCs AND detailed negative pregnancy outcomes) as well as by scanning references from already included articles and relevant reviews manually. Because environmental factors and EDCs have been associated to epigenetic alterations, special care has been given to EDC-induced transgenerational effects on pregnancy outcomes.

RESULTS

The existing evidence suggests positive associations between specific environmental factors and negative pregnancy outcomes such as ectopic pregnancies, pregnancy losses, gestational diabetes, hypertensive disorders of pregnancy, preterm births, birth defects, intrauterine growth restriction, and small or large for gestational age babies.

CONCLUSION

Environmental factors and EDCs may have a catalytic effect on the course and the outcomes of pregnancy.

Reproductive toxicity of maternal exposure to di(2-ethylhexyl)phthalate and butyl paraben (alone or in association) on both male and female Wistar offspring

Parabens and phthalates are commonly found as contaminants in human fluids and are able to provoke reproductive toxicity, being considered endocrine disruptors. To evaluate the effects of phthalate and paraben, alone or in combination, on reproductive development of the offspring, female pregnant Wistar rats were allocated in six experimental groups: Three control groups (gavage [CG], subcutaneous [CS], and gavage + subcutaneous) received corn oil as vehicle, and the remaining groups were exposed to di(2-ethylhexyl)phthalate (DEHP) (500 mg/kg, gavage), butyl paraben (BP) (100 mg/kg, subcutaneously), or MIX (DEHP + BP), from Gestational Day 12 until Postnatal Day (PND) 21. The following parameters were assessed on the offspring: anogenital distance and weight at PND 1, nipple counting at PND 13, puberty onset, estrous cycle, weights of reproductive and detoxifying organs, histological evaluation of reproductive organs, and sperm evaluations (counts, morphology, and motility). Female pups from MIX group presented reduced body weight at PND 1, lower AGD, and decreased endometrium thickness. Male animals showed decreased body weight at PND 1 and lower number of Sertoli cells on DEHP and MIX groups, MIX group revealed increase of abnormal seminiferous tubules, DEHP animals presented delayed preputial separation and higher percentage of immotile sperms, and BP males presented diminished number of Leydig cells. In conclusion, the male offspring was more susceptible to DEHP toxicity; even when mixed to paraben, the main negative effects observed seem to be due to antiandrogenic phthalate action. On the other hand, DEHP seems to be necessary to improve the effects of BP on reducing estrogen-dependent and increasing androgen-dependent events.

Ovarian volume partially explains associations of phthalate biomarkers with anti-Müllerian hormone and estradiol in midlife women

BACKGROUND/OBJECTIVES

Women are ubiquitously exposed to endocrine disruptors, including phthalates. Ovarian follicles undergoing folliculogenesis (indirectly measured by ovarian volume) produce anti-Müllerian hormone (AMH) and estradiol (E2). We evaluated associations of phthalates with ovarian volume to assess whether this explained prior positive associations of phthalates with AMH and E2.

METHODS

Women ages 45-54 years (n = 614) had transvaginal ultrasounds of right/left ovaries to calculate mean ovarian volume. Women provided up-to-four urine and blood samples for quantifying AMH (first serum sample), E2 (all serum samples), and nine phthalate metabolites (from pooled urine, representing six parent phthalates). Multivariable linear or logistic regression models (for individual phthalate biomarkers), as well as weighted quantile sum (WQS) regression (for mixture analyses) evaluated associations of phthalate biomarkers with ovarian volume. Using cross-sectional mediation analysis, we assessed whether associations of phthalates with ovarian volume partially explained those of phthalates with AMH or E2.

RESULTS

Most women were non-Hispanic White (68%) and pre-menopausal (67%) with higher urinary phthalate metabolite concentrations than U.S. women. In single-pollutant models, 10% increases in mono(3-carboxypropyl) phthalate (MCPP) and monobenzyl phthalate (MBzP) were associated with 0.44% (95% CI: -0.02%, 0.91%) and 0.62% (95% CI: 0.02%, 1.23%) larger ovarian volumes, respectively. As a cumulative mixture, 10% increases in the phthalate mixture were associated with 2.89% larger ovarian volume (95%CI: 0.27, 5.59) with MCPP (35%) and MBzP (41%) identified as major contributors. Higher ovarian volume due to a 10% increase in MBzP (indirect effect OR: 1.004; 95% CI: 1.00, 1.01) explained 16% of the positive association between MBzP and higher AMH, whereas higher ovarian volume due to a 10% increase in MCPP (indirect effect %Δ: 0.11; 95% CI: -0.01, 0.22) explained 23% of the positive association between MCPP and E2.

CONCLUSION

In this cross-sectional study, phthalates were associated with increased ovarian volume, with implications for midlife hormone production.

Extent of exposure to scented candles and prevalence of respiratory and non-respiratory symptoms amongst young university students

BACKGROUND

Incense burning such as scented candles are commonly used in Arabian Gulf regions as it is thought to produce relaxing effects on people's mood. This study is conducted to examine the prevalence of scented candles' usage, extent of exposure and its effects on individuals' health based on symptoms prevalence in young university students.

MATERIAL AND METHOD

A cross-sectional study was conducted on university students from different regions in Saudi Arabia. Data was collected in March 2020 using an online questionnaire survey adapted from The European Community Respiratory Health Survey-II (ECRHS-II). Inclusion criterion for recruitment was students with non-smoking status. Descriptive statistics were used to report demographic data on the extent of exposure to scented candles (in terms of frequency and duration) and the presence of symptoms. Multiple logistic regression analysis was used to assess the relationship between scented candles exposure and respiratory and other health-related problems.

RESULTS

The prevalence of scented candles usage was 65.7% (472/718) among the respondents. However, its pervasiveness was significantly higher in females than in male respondents (74.9% vs. 28.4%; p = 0.0001). Among the scented candle users, 34.8% of the respondents used the scented candles more than 4 times a month and 40.2% of the respondents lit the scented candles for 20-40 min. A total of 117 (24.8%) respondents reported health-related problem and the top three health problems were headache 72 (15.2%), shortness of breath 42 (8.9%) and cough 37 (7.8%). The scented candle usage 5-6 times a week showed significantly lower wheezing (OR = 0.10, 95%CI 0.02-0.54, p = 0.008). The duration of more than 60 min of scented candle exposure showed higher occurrence of headache 1.42 times (95% CI = 0.68-2.96), sneezing 1.29 times (95% CI = 0.42-4.00) and wheezing 1.23 times (95% CI = 0.48-3.13), though the association was not significant.

CONCLUSION

The results show that scented candle usage is more prevalent among female university students in Saudi Arabia. The common health-related problems associated with scented candle exposure were headache, shortness of breath and coughing.

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

OBJECTIVE

Women 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.

METHODS

In 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.

RESULTS

We 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.

CONCLUSIONS

Within 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.

Ovarian Reserve Disorders, Can We Prevent Them? A Review

The ovarian reserve is finite and begins declining from its peak at mid-gestation until only residual follicles remain as women approach menopause. Reduced ovarian reserve, or its extreme form, premature ovarian insufficiency, stems from multiple factors, including developmental, genetic, environmental exposures, autoimmune disease, or medical/surgical treatment. In many cases, the cause remains unknown and resulting infertility is not ultimately addressed by assisted reproductive technologies. Deciphering the mechanisms that underlie disorders of ovarian reserve could improve the outcomes for patients struggling with infertility, but these disorders are diverse and can be categorized in multiple ways. In this review, we will explore the topic from a perspective that emphasizes the prevention or mitigation of ovarian damage. The most desirable mode of fertoprotection is primary prevention (intervening before ablative influence occurs), as identifying toxic influences and deciphering the mechanisms by which they exert their effect can reduce or eliminate exposure and damage. Secondary prevention in the form of screening is not recommended broadly. Nevertheless, in some instances where a known genetic background exists in discrete families, screening is advised. As part of prenatal care, screening panels include some genetic diseases that can lead to infertility or subfertility. In these patients, early diagnosis could enable fertility preservation or changes in family-building plans. Finally, Tertiary Prevention (managing disease post-diagnosis) is critical. Reduced ovarian reserve has a major influence on physiology beyond fertility, including delayed/absent puberty or premature menopause. In these instances, proper diagnosis and medical therapy can reduce adverse effects. Here, we elaborate on these modes of prevention as well as proposed mechanisms that underlie ovarian reserve disorders.

Association between co-exposure to phenols and phthalates mixture and infertility risk in women

BACKGROUND

Exposure to phenols and phthalates has been separately linked to increased risks of infertility in women of reproductive age. However, the combined effect of phenols and phthalates exposure on infertility has not been explored.

METHODS

Data from the National Health and Nutrition Examination Surveys (NHANES) were used. A total of 857 women of reproductive age (18-45 years) with available information on urinary phenol and phthalate metabolites, reproductive questionnaires, and covariates were included in the present study. The definition of infertility was based on self-reports. Multivariable logistic regression, principal component analysis (PCA), and Bayesian kernel machine regression (BKMR) with stratified variable selection were applied to determine what associations were found between combined exposure to these mixtures and risk of infertility among women of reproductive age.

RESULTS

After adjusting for potential confounders, bisphenol A (BPA), mono(3-carboxypropyl) phthalate (MCPP) and four di(2-ethylhexyl) phthalate (DEHP) metabolites [mono(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) and mono(2-ethyl-5-carboxypentyl) phthalate (MECPP)] were positively associated with infertility. PCA revealed that the DEHP-BPA factor's PC score was significantly positively related to the likelihood of infertility [adjusted odds ratio (aOR) = 1.45; 1.08, 1.82]. The DEHP-BPA component consistently had the highest group posterior inclusion probability (PIP) in BKMR models. The BKMR model also found that MEOHP, MEHHP, and BPA were positively associated with infertility risk when the remaining combination concentrations were held at their median values. In addition, we observed that the probability of infertility increased dramatically as the quantiles of total mixture concentration increased.

CONCLUSION

Our findings indicate that a combination of phenol and phthalate metabolites is linked to infertility among reproductive-age women. BPA and DEHP, in particular, are significantly related to the risk of infertility.

The effects of endocrine-disrupting chemicals on ovarian- and ovulation-related fertility outcomes

Exposure to endocrine-disrupting chemicals (EDCs) is unavoidable, which represents a public health concern given the ability of EDCs to target the ovary. However, there is a large gap in the knowledge about the impact of EDCs on ovarian function, including the process of ovulation. Defects in ovulation are the leading cause of infertility in women, and EDC exposures are contributing to the prevalence of infertility. Thus, investigating the effects of EDCs on the ovary and ovulation is an emerging area for research and is the focus of this review. The effects of EDCs on gametogenesis, uterine function, embryonic development, and other aspects of fertility are not addressed to focus on ovarian- and ovulation-related fertility issues. Herein, findings from epidemiological and basic science studies are summarized for several EDCs, including phthalates, bisphenols, per- and poly-fluoroalkyl substances, flame retardants, parabens, and triclosan. Epidemiological literature suggests that exposure is associated with impaired fecundity and in vitro fertilization outcomes (decreased egg yield, pregnancies, and births), while basic science literature reports altered ovarian follicle and corpora lutea numbers, altered hormone levels, and impaired ovulatory processes. Future directions include identification of the mechanisms by which EDCs disrupt ovulation leading to infertility, especially in women.

Association between environmental pollutants and the FSH/AMH ratio as a marker of ovarian reserve

The ovarian function decreases with age, and various markers, such as follicle stimulating hormone, inhibin B, antral follicle count, and anti-Müllerian hormone, are used for its evaluation. Recently, exposure to various environmental pollutants in daily life has been reported as an important cause of ovarian function decline. Therefore, the present study aimed to confirm the effect of environmental pollutants on the relationship between age and decline in ovarian function. The exposure levels of 16 environmental pollutants were evaluated in women aged 26-40 years, and the AMH levels and FSH/AMH ratios were used as markers for the decline of ovarian function. The participants were divided into two groups: low-level or high-level for each environmental pollutant if their exposure level was below or above the median respectively. The slope of the decrease or increase in the AMH level and FSH/AMH ratio of each group with age was evaluated. The FSH/AMH ratio better presented the difference in the rate of change with age in each group than did AMH alone. In particular, the rate of change in the FSH/AMH ratio increased 5.2 and 3.7 times (p<0.05) in the group exposed to high levels of the volatile organic compound metabolite, trans, trans-muconic acid and the polycyclic aromatic hydrocarbons metabolite, 2-hydroxynaphthalene, respectively, than in the low-level exposure groups for those metabolites. This study confirmed that environmental pollutants influenced the rate of change in the FSH/AMH ratio with age. Further studies on larger populations are necessary in the future.

The Joint Effect of Perceived Psychosocial Stress and Phthalate Exposure on Hormonal Concentrations during the Early Stage of Pregnancy: A Cross-Sectional Study

Phthalates alter the hormonal balance in humans during pregnancy, potentially affecting embryonic and fetal development. We studied the joint effect of exposure to phthalates, quantified by urinary phthalate metabolite concentration, and perceived psychological stress on the concentration of hormones in pregnant women (n = 90) from the Nitra region, Slovakia, up to the 15th week of pregnancy. We used high-performance liquid chromatography, tandem mass spectrometry (HPLC-MS/MS), and electro-chemiluminescence immunoassay to determine urinary concentrations of phthalates and serum concentrations of hormones, respectively. We used Cohen perceived stress scale (PSS) to evaluate the human perception of stressful situations. Our results showed that mono(carboxy-methyl-heptyl) phthalate (cx-MiNP) and a molar sum of di-iso-nonyl phthalate metabolites (ΣDiNP) were negatively associated with luteinizing hormone (LH) (p ≤ 0.05). Mono(hydroxy-methyl-octyl) phthalate (OH-MiNP) and the molar sum of high-molecular-weight phthalate metabolites (ΣHMWP) were positively associated with estradiol (p ≤ 0.05). PSS score was not significantly associated with hormonal concentrations. When the interaction effects of PSS score and monoethyl phthalate (MEP), cx-MiNP, ΣDiNP, and ΣHMWP on LH were analyzed, the associations were positive (p ≤ 0.05). Our cross-sectional study highlights that joint psychosocial stress and xenobiotic-induced stress caused by phthalates are associated with modulated concentrations of reproductive hormones in pregnant women.

The association of serum phthalate metabolites with biomarkers of ovarian reserve in women of childbearing age

Phthalates (PAEs) are widely used plasticizers drawing increasing concern due to reproductive toxicity. However, studies on serum PAEs metabolites (mPAEs) and their associations with human ovarian function remain very scarce. In this study, from April 2019 to August 2020, a total of 297 women of childbearing age were recruited in Tianjin, China. Eleven mPAEs were analyzed in serum samples and eight mPAEs were detected at frequencies > 65% with median concentrations of 0.43-15.3 ng/mL. In multinomial logistic analysis, an increase in serum mono (2-isobutyl) phthalate (miBP) was associated with decline in antral follicle count (AFC) (OR=1.26, 95% CI: 0.99, 1.61) and 5-mono-(2-ethyl-5-hydroxyhexyl) phthalate (mEHHP) was significantly associated with AFC increase (OR=1.43, 95% CI: 1.06, 1.92), which were aligned with the associations found between mPAEs and AMH through generalized linear regression. In multiple linear regression models, per 10% increase in serum mono (2-ethylhexyl) phthalate (mEHP), mono (2-ethyl-5-oxohexyl) phthalate (mEOHP) (oxo-mEHP), and principal component 1 featured for high concentrations of mono-n-butyl phthalate (mBP), miBP and mEHP were associated with 0.15 (95% CI: -0.29, -0.02), 0.01 (95% CI: -0.01, 0.00) and 0.01 (95% CI: -0.02, 0.00) ln-unit decrease in estradiol (E2) levels, respectively, while mono-[(2-carboxymethyl) hexyl] phthalate (mCMHP) (carboxymethyl-mEHP) was positively associated with 0.05 ln-unit increase of E2 (95% CI: 0.02, 0.08). The observed negative associations between mPAEs and the Anti-Müllerian hormone (AMH) also aligned with the change in AFC. Generalized linear regression also revealed nonlinear associations between mono-ethyl phthalate (mEP), mCMHP and follicle-stimulating hormone (FSH). Overall, serum mEHP and its metabolites were negatively associated with E2. miBP was negatively associated with AFC. The nonlinear associations between mPAEs and FSH, and AMH need further study.

Endocrine disrupting chemicals impact on ovarian aging: Evidence from epidemiological and experimental evidence

Endocrine-disrupting chemicals (EDCs) are ubiquitous in daily life, but their harmful effects on the human body have not been fully explored. Recent studies have shown that EDCs exposure could lead to infertility, menstrual disorder and menopause, resulting in subsequent effects on female health. Therefore, it is of great significance to clarify and summarize the impacts of EDCs on ovarian aging for explaining the etiology of ovarian aging and maintaining female reproductive health. Here in this review, we focused on the impacts of ten typical environmental contaminants on the progression of ovarian aging during adult exposure, including epidemiological data in humans and experimental models in rodents, with their clinical phenotypes and underlying mechanisms. We found that both persistent (polychlorinated biphenyls, perfluoroalkyl and polyfluoroalkyl substances) and non-persistent (phthalates) EDCs exposure could increase an overall risk of ovarian aging, leading to the diminish of ovarian reserve, decline of fertility or fecundity, irregularity of the menstrual cycle and an earlier age at menopause, and/or premature ovarian insufficiency/failure in epidemiological studies. Among these, the loss of follicles can also be validated in experimental studies of some EDCs, such as BPA, phthalates, parabens and PCBs. The underlying mechanisms may involve the impaired ovarian follicular development by altering receptor-mediated pro-apoptotic pathways, inducing signal transduction and cell cycle arrest and epigenetic modification. However, there were inconsistent results in the impacts on fertility/fecundity, menstrual/estrous cycle and hormone changes response to different EDCs, and differences between human and animal studies. Our review summarizes the current state of knowledge on ovarian disrupters, highlights their risks to ovarian aging and identifies knowledge gaps in humans and animals. We therefore propose that females adopt healthy lifestyle changes to minimize their exposure to both persistent and non-persistent chemicals, that have the potential damage to their reproductive function.

Multigenerational Effects of an Environmentally Relevant Phthalate Mixture on Reproductive Parameters and Ovarian miRNA Expression in Female Rats

Phthalates are endocrine-disrupting chemicals used in many consumer products. Our laboratory previously developed an environmentally relevant phthalate mixture consisting of 6 phthalates and found that it disrupted female fertility in mice. However, it was unknown if maternal exposure to the mixture affects reproductive parameters and ovarian post-transcription in the F1 and F2 generation of female rats. Thus, we tested the hypothesis that maternal exposure to the phthalate mixture affects folliculogenesis, steroidogenesis, and ovarian microRNA (miRNA) in the F1 and F2 generations of female rats. Pregnant female rats were divided into 4 groups and orally dosed daily from gestational day 10 to postnatal day 21 with corn oil (control group), 20 μg/kg/day, 200 μg/kg/day, or 200 mg/kg/day of the phthalate mixture. Maternal exposure to the phthalate mixture impaired folliculogenesis in the F1 and F2 generations of female rats and affected steroidogenesis in the F1 generation of female rats compared to control. Further, the phthalate mixture altered ovarian expression of some genes related to the cell cycle and steroidogenesis compared to control in the F1 and F2 generations of female rats. The mixture also increased ovarian expression of rno-mir-184 that is involved with the oocyte maturation process. Collectively, our data show that maternal exposure to the phthalate mixture affects folliculogenesis and steroidogenesis in the F1 and F2 generations of female rats and alters ovarian miRNA expression in the F1 generation of female rats.

Impacts of endocrine disrupting chemicals on reproduction in wildlife and humans

Endocrine disrupting chemicals (EDCs) are ubiquitous in aquatic and terrestrial environments. The main objective of this review was to summarize the current knowledge of the impacts of EDCs on reproductive success in wildlife and humans. The examples selected often include a retrospective assessment of the knowledge of reproductive impacts over time to discern how the effects of EDCs have changed over the last several decades. Collectively, the evidence summarized here within reinforce the concept that reproduction in wildlife and humans is negatively impacted by anthropogenic chemicals, with several altering endocrine system function. These observations of chemicals interfering with different aspects of the reproductive endocrine axis are particularly pronounced for aquatic species and are often corroborated by laboratory-based experiments (i.e. fish, amphibians, birds). Noteworthy, many of these same indicators are also observed in epidemiological studies in mammalian wildlife and humans. Given the vast array of reproductive strategies used by animals, it is perhaps not surprising that no single disrupted target is predictive of reproductive effects. Nevertheless, there are some general features of the endocrine control of reproduction, and in particular, the critical role that steroid hormones play in these processes that confer a high degree of susceptibility to environmental chemicals. New research is needed on the implications of chemical exposures during development and the potential for long-term reproductive effects. Future emphasis on field-based observations that can form the basis of more deliberate, extensive, and long-term population level studies to monitor contaminant effects, including adverse effects on the endocrine system, are key to addressing these knowledge gaps.

Effect of ambient air pollutants on in vitro fertilization-embryo transfer pregnancy outcome in Zhengzhou, China

With the acceleration of China's urbanization and industrialization, air pollution has become a major environmental problem. Retrospective data analysis of 6564 patients who underwent IVF-ET in the center for reproductive medicine of the First Affiliated Hospital of Zhengzhou University from 2015 to 2020. Different stages were selected from 90 days before oocyte retrieval to 35 days after transfer and divided into five exposure periods. Multivariate logistic regression was used to analyze the relationship between six ambient air pollutants (PM_2.5, PM₁₀, NO₂, SO₂, CO and O₃) and the IVF-ET pregnancy outcome. The results showed that air pollutants can significantly affect the IVF pregnancy outcome. The harmful effects of ambient air pollutants are more obvious in the patients aged < 35 years, single embryo transfer and cleavage stage embryo transfer.