A pilot investigation of couple-level phthalates exposure and in vitro fertilization (IVF) outcomes

In vivo gamete toxicology in the context of in vitro fertilization: a narrative review

IVF as a clinical method to surmount infertility has existed since the 1970s, and yet fertilization, embryo development, pregnancy, and live birth rates remain unacceptably low. Although a multitude of factors may contribute to stagnated success despite substantial advances in basic and applied IVF sciences, gamete quality is inarguably integral to IVF success rates. In this review, the authors will explore the role of environmental toxicology in impairing in vivo fertility and gamete quality prior to starting IVF that will influence downstream IVF success. In vivo contaminants of interest that may affect gamete potential in the context of IVF include heavy metals, per- and polyfluoroalkyl substances (PFAS), persistent organic pollutants (POPs), and airborne contaminants. By evaluating the current literature on reproductive toxicology and how toxic exposures may influence IVF, this review aims to provide a comprehensive reference of potential toxicological exposures for clinicians, to use in vitro and animal data to supplement correlative human studies with potential causative mechanisms, and to strengthen the case for patient assessment of toxicological risk.

Neurodevelopmental toxicity and mechanism of action of monoethylhexyl phthalate (MEHP) in the developing zebrafish (Danio rerio)

Monoethylhexyl phthalate (MEHP) is the primary metabolite of di(2-ethylhexyl) phthalate (DEHP), the most prevalent phthalate plasticiser globally. It has been demonstrated that MEHP exerts more potent toxic effects than DEHP. Nevertheless, the full extent of the toxicity of MEHP to neurodevelopmental organisms remains unclear. Accordingly, the present study was designed to investigate the neurodevelopmental toxicity of MEHP exposure and the underlying molecular mechanisms. Zebrafish juveniles were exposed to different concentrations of MEHP (7.42, 14.84, 29.68 and 74.2 μg/L) for a period of four weeks. Immunohistological evidence indicated that MEHP exposure resulted in oxidative stress and apoptosis in the developing zebrafish brain. Subsequently, the neurobehaviour of zebrafish larvae was evaluated, and it was determined that MEHP significantly disrupted their locomotor capacity, motor vigor, and social conduct. Furthermore, HE staining revealed damage to brain neurons, which may be linked to impaired synthesis and conduction of inter-synaptic neurotransmitters. Transcriptomic analyses indicated that MEHP may affect the expression levels of genes in the P53 signalling pathway and signalling pathways related to the development of the nervous system. This results in impaired functions, including nerve conduction and neuronal development. Additionally, it induces oxidative stress, which leads to significant brain cell apoptosis and, ultimately, neurotoxicity in developing zebrafish.

IMPACT OF REAL-LIFE ENVIRONMENTAL EXPOSURES ON REPRODUCTION: Phthalates disrupt female reproductive health: a call for enhanced investigation into mixtures

In brief

Exposure to phthalates, known endocrine-disrupting chemicals (EDCs), is ubiquitous, but the effects on women's reproductive health are largely unknown. This review summarizes the literature investigating associations between phthalate exposures and clinical reproductive outcomes and reproductive disease states in women, and it emphasizes the need to investigate the effects of phthalate mixtures on women's reproductive health.

Abstract

Daily exposure to a mixture of phthalates is unavoidable in humans and poses a risk to reproductive health because they are known EDCs. Specific to female reproductive health, the literature has linked phthalate exposure to impairments in ovarian function, uterine function, pregnancy outcomes and endocrine signaling in the hypothalamic-pituitary-ovarian axis. However, limitations of these studies are that they primarily focus on single-phthalate exposures in animal models. Thus, the effects of real-life exposures to mixtures of phthalates and the clinical and translational impacts on reproductive function in women are largely unknown. This review summarizes the recent literature specifically investigating associations between phthalate mixture exposures and clinical reproductive outcomes and reproductive disease states in women. Because these studies are scarce, they are supplemented with the literature utilizing single-phthalate analyses in women and mechanistic basic science studies using phthalate mixture exposures. Main findings from the literature suggest that elevated phthalate exposure is associated with altered menstrual cyclicity, altered pubertal timing, disrupted ovarian folliculogenesis and steroidogenesis, ovarian disorders including primary ovarian insufficiency and polycystic ovary syndrome, uterine disorders including endometriosis and leiomyomas, poor in vitro fertilization outcomes and poor pregnancy outcomes. There is an urgent need to better incorporate phthalate mixtures in epidemiology (mixture analyses) and basic science (direct exposures) study designs. Furthermore, as exposure to multiple phthalates is ubiquitous, elucidating the mechanism of phthalate mixture toxicities is paramount for improving women's reproductive health.

Phthalate exposures, blood coagulation function, and assisted reproductive technology outcomes: Results from the TREE cohort study

BACKGROUND

Phthalate exposures have been shown to be inversely associated with reproductive success among women undergoing assisted reproductive technology (ART). However, the underlying mechanisms are unknown.

OBJECTIVES

To explore blood coagulation function as the mediating role of associations between exposure to phthalates and ART outcomes.

METHODS

A total of 735 women from the Tongji Reproductive and Environmental (TREE) study were included. Urine samples collected at recruitment were quantified for 8 phthalate metabolites, and blood clotting time and platelet indices were also determined. Generalized linear regression, logistic regression, weighted quantile sum (WQS) regression, or Bayesian kernel machine regression (BKMR) models were applied to investigate the associations among individual and mixture of phthalate metabolites, blood coagulation parameters, and ART outcomes. The mediation role of blood coagulation parameters was estimated by mediation analysis.

RESULTS

Mono-n-butyl phthalate (MBP), mono-isobutyl phthalate (MiBP), monobenzyl phthalate (MBzP), mono(2-ethyl-5-carboxypentyl) phthalate (MECPP), and molar sum of di(2-ethylhexyl) phthalate metabolites (∑DEHP) were positively associated with platelet indices. Phthalate metabolite mixture was also positively associated with platelet count (PLT), mean platelet volume (MPV), and plateletcrit (PCT), whereas inversely associated with international normalized ratio (INR). Meanwhile, PLT and PCT were inversely associated with the odds of implantation success and live birth, while prothrombin time and INR were positively associated with the odds of implantation success. Mediation analyses showed indirect effects of above-mentioned phthalate metabolites and phthalate mixture on the odds of implantation success and live birth through PLT or PCT, with the proportion mediated ranging from 3.44% to 8.96%.

CONCLUSIONS

Phthalates may increase the risks of ART failure through enhancing blood coagulation function. More studies are warranted to verify the findings.

Phthalate monoesters affect membrane fluidity and cell-cell contacts in endometrial stromal adherent cell lines and spheroids

Phthalate monoesters have been identified as endocrine disruptors in a variety of models, yet understanding of their exact mechanisms of action and molecular targets in cells remains incomplete. Here, we set to determine whether epidemiologically relevant mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) can affect biological processes by altering cell plasma membrane fluidity or formation of cell-cell contacts. As a model system, we chose endometrial stromal cell lines, one of which was previously used in a transcriptomic study with MEHHP or MEHHP-containing mixtures. A short-term exposure (1 h) of membrane preparations to endocrine disruptors was sufficient to induce changes in membrane fluidity/rigidity, whereas different mixtures showed different effects at various depths of the bilayer. A longer exposure (96 h) affected the ability of cells to form spheroids and highlighted issues with membrane integrity in loosely assembled spheroids. Finally, in spheroids assembled from T-HESC cells, MEHHP interfered with the formation of cell-cell contacts as indicated by the immunostaining of zonula occludens 1 protein. Overall, this study emphasized the need to consider plasma membrane, membrane-bound organelles, and secretory vesicles as possible biological targets of endocrine disruptors and offered an explanation for a multitude of endocrine disruptor roles documented earlier.

Association of phthalate exposure with reproductive outcomes among infertile couples undergoing in vitro fertilization: A systematic review

Human fertility is impacted by changes in lifestyle and environmental deterioration. To increase human fertility, assisted reproductive technology (ART) has been extensively used around the globe. As early as 2009, the Endocrine Society released its first scientific statement on the potential adverse effects of environmental endocrine-disrupting chemicals (EDCs) on human health and disease development. Chemicals known as phthalates, frequently employed as plasticizers and additives, are common EDCs. Numerous studies have shown that phthalate metabolites in vivo exert estrogen-like or anti-androgenic effects in both humans and animals. They are associated with the progression of a range of diseases, most notably interference with the reproductive process, damage to the placenta, and the initiation of chronic diseases in adulthood. Phthalates are ingested by infertile couples in a variety of ways, including household products, diet, medical treatment, etc. Exposure to phthalates may exacerbate their infertility or poor ART outcomes, however, the available data on phthalate exposure and ART pregnancy outcomes are sparse and contradictory. Therefore, this review conducted a systematic evaluation of 16 papers related to phthalate exposure and ART pregnancy outcomes, to provide more aggregated results, and deepen our understanding of reproductive outcomes in infertile populations with phthalate exposure.

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.

One Health challenges for pig reproduction

The current state of the world challenges pig reproduction as an important part of One Health, which involves interrelationships between animal, human and environmental health. The One Health concept underlines a comparative aspect in reproductive physiology and disease occurrence, bridging knowledge from one species to another. Seasonal changes in the environment affect pig reproduction and climate change may further strengthen those effects. Endocrine-disrupting chemicals (EDCs), and specifically phthalates and heavy metals, interfere with endocrine function, and thereby sexual behavior, fertilization capacity and steroidogenesis. Reproductive infections and extended semen storage are important indications for antimicrobial use. Innovative solutions are needed to explore alternatives to antimicrobials. Efforts to ensure reproductive efficiency have prolonged farrowing as litter size has doubled over the past three decades, compromising immune transfer and welfare. Physiological, metabolic and programming related events around parturition are key areas for future One Health research in pig reproduction. In conclusion, climate change challenges reproductive management and breeding. More resilient pigs that can tolerate harsh environment but maintain high reproductive performance are needed. EDCs continue to grow as an environmental challenge for reproductive management and alternatives to antibiotics will be required.

The impact of air pollution and endocrine disruptors on reproduction and assisted reproduction

PURPOSE OF REVIEW

Rapid increase in world population accompanied by global industrialization has led to an increase in deployment of natural resources, resulting in growing levels of pollution. Here, we review recent literature on the impact of environmental pollution on human reproductive health and assisted reproduction outcomes, focusing on two of the most common: air pollution and endocrine disruptors.

RECENT FINDINGS

Air pollution has been associated with diminished ovarian reserve, uterine leiomyoma, decreased sperm concentration and motility. Air pollution also correlates with decreased pregnancy rates in patients undergoing infertility treatment using in-vitro fertilization (IVF). Similarly, Bisphenol A (BPA), a well studied endocrine disrupting chemical, with oestrogen-like activity, is associated with diminished ovarian reserve, and abnormal semen parameters, while clinical implications for patients undergoing infertility treatment remain to be established.

SUMMARY

There is convincing evidence that environmental pollutants may have a negative impact on human health and reproductive potential. Air pollutions and endocrine disrupting chemicals found in water and food seem to affect male and female reproductive function. Large-scale studies are needed to determine the threshold values for health impact that may drive targeted policies.

Lack of association between endocrine disrupting chemicals and male fertility: A systematic review and meta-analysis

The incidence of infertility currently affects about 15% of the world's population. Male factors are estimated to be responsible for up to 40-50% of these cases. While the cause of these reproductive disorders is still unclear, the exposure to a family of ubiquitous compounds in our daily life, named endocrine disrupting chemicals (EDCs) could be involved. This paper was aimed at performing a systematic review and meta-analysis of population studies exploring whether human male exposure to EDCs affects male fertility. Clinical and observational studies assessing the exposure to EDCs along with sperm quality, the most common reproductive disorders, sperm DNA damage, sperm oxidative stress, fertilization rate, implantation rate, clinical pregnancy rate, live birth rate, and miscarriage rate were included. The quality assessment tool from the NHLBI-NIH was used to assure that studies met standardized quality criteria. Sensitivity analysis and heterogeneity among studies was assessed. Overall, the 32 selected articles, including 7825 individuals in the systematic review, explored 12 families of EDCs. The results revealed a high heterogeneity among studies in relation to the association between exposure to EDCs and the endpoints analyzed. Meta-analyses were performed with data from 7 articles including 479 individuals, 4 articles assessing the association between BPA in urine and sperm quality, and 3 articles evaluating PCB153 in serum and sperm quality. In the meta-analysis, we identified an unpredicted significant positive association between PCB153 exposure and sperm concentration. However, it would not be clinically relevant. No positive or inverse associations were found neither for BPA, nor for PCB153 and the rest of sperm parameters analyzed. The high disparity between studies made difficult to draw conclusions on the potential harmful effects of EDCs on male fertility. Consequently, to delineate the potential relationship that EDCs can have on male fertility, an important condition stressing the health system, further investigations are required.

Association of phthalate exposure with low birth weight in couples conceiving naturally or via assisted reproductive technology in a prospective birth cohort

BACKGROUND

Few studies have investigated the adverse effects of preconception phthalate (PAE) exposure on birth weight in couples receiving assisted reproductive technology (ART) compared to naturally conceived newborns.

OBJECTIVES

We examined the association between parental preconception/prenatal urinary phthalate exposure and low birth weight (LBW) risk in couples who conceived using ART or naturally.

METHODS

From the Jiangsu Birth Cohort Study (China), we recruited 544 couples who conceived after infertility treatment and 940 couples who conceived naturally and gave birth to a singleton infant between November 2014 and December 2019. Seventeen metabolites of phthalate and three metabolites of phthalate alternatives were analyzed in parental spot urine samples. Clinical data were collected from medical records. We used generalized linear models, elastic net regression, Bayesian kernel machine regression, and quantile-based g-computation to examine the individual and joint effects of parental phthalate exposure on birth weight and LBW risk ratios (RR).

RESULTS

The relationship between parental phthalate exposure and birth weight was consistent between ART and natural conception. Maternal exposure to mono-ethyl phthalate and mono-carboxyisooctyl phthalate was associated with an increased risk of LBW in ART-conceived infants (RR = 1.27; 95 % confidence interval (CI): 1.03, 1.56; and RR = 1.31; 95 % CI: 1.03, 1.67, respectively). In contrast, in the spontaneously conceived infants, higher paternal prenatal concentrations of mono-benzyl phthalate and mono-carboxyisononyl phthalate were associated with a 40 % and 53 % increase in LBW risk, respectively. Exposure to PAE mixtures was associated with LBW in ART-conceived infants, with the effects primarily driven by di-ethyl phthalate, benzylbutyl phthalate, and di-isononyl phthalate metabolites. Sex-specific LBW was observed, with females appearing to be more susceptible than males.

CONCLUSIONS

Maternal preconception and paternal prenatal exposure to phthalates were associated with increased risk of LBW in infants. Compared with natural conception, ART-conceived fetuses were more sensitive to PAE mixtures, which requires further attention.

Impact of mono(2-ethylhexyl) phthalate (MEHP) on the development of mouse embryo in vitro

Mono(2-ethylhexyl) phthalate (MEHP) is the most studied metabolite of di(2-ethylhexyl) phthalate (DEHP), a phthalate found in cosmetics, flooring, paints, and plastics products, including toys and medical tubing. Humans are frequently exposed to this compound due to its ubiquitous presence in our environment. DEHP and MEHP are known to be endocrine-disrupting chemicals and exposure levels have been associated to decreased reproductive success. However, few studies have focused on the direct effects of MEHP on embryos. The present study investigated effects of MEHP (0.1, 1, 10, 100 and 1000 µM) on mice preimplantation embryonic development, evaluating percentage of blastocyst formation, hatching from zona pellucida, methylation-related genes, cell lineage commitment, micronucleation, and adherens junction marker at different stages of development during in vitro culture for 6 days. We show MEHP negatively impacts embryo competence by reducing blastocyst formation and hatching at 100 and 1000 µM. In addition, 100 µM MEHP increases the expression of Tet3 gene in blastocysts, which is related to a reduction of DNA methylation, an important mechanism regulating gene expression. Exposed embryos that completed the hatching process in groups 0.1, 1 and 10 µM MEHP had similar number of inner cell mass and trophectoderm cells compared to the control, while micronucleation occurrence and E-cadherin expression was not affected in exposed morulae by MEHP at 10 or 100 µM. Our results showed that high concentrations of MEHP can negatively impact embryo development. New studies unveiling the mechanism of toxicity involved and encompassing further developmental stages are warranted for further understanding.

Health effects associated with phthalate activity on nuclear receptors

Phthalates are endocrine disruptors, widely used as plasticizers to impart flexibility in plastics, and as solvents in personal care products. Due to their nearly ubiquitous use in consumer products, most humans are exposed to phthalates daily. There has been extensive research on the reproductive health effects associated with phthalate exposure, but less attention has been paid to other actions. This review aims to summarize the known action of phthalates on different nuclear receptors. Some phthalates bind to and activate the estrogen receptor, making them weakly estrogenic. However, other phthalates antagonize androgen receptors. Some high molecular weight phthalates antagonize thyroid receptors, affecting metabolism. Several phthalates activate and interfere with the normal function of different peroxisome proliferator-activated receptors (PPARs), receptors that have critical roles in lipid metabolism and energy homeostasis. Some phthalates activate the aryl hydrocarbon receptor, which is critical for xenobiotic metabolism. Although phthalates have a short half-life in vivo, because people are continuously exposed, studies should examine the health effects of phthalates associated with long-term exposure. There is limited research on the effects of phthalates on health outcomes aside from reproductive function, particularly concerning are childhood adiposity, behavior, and learning. There is also limited information on actions of phthalates not mediated via nuclear receptors. Humans are exposed to multiple chemicals simultaneously, and how chemical mixtures act on nuclear receptor activity needs study. Although we know a great deal about phthalates, there is still much that remains uncertain. Future studies need to further examine their other potential health effects.

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.

Specific lifestyle factors and in vitro fertilization outcomes in Romanian women: a pilot study

Background

Infertility is an important health concern worldwide. Although lifestyle habits and behaviors have been widely reported as predictors of IVF outcomes by previous studies, they have not been reported for Romanian women undergoing IVF. In this regard, our pilot study aimed to begin to address the data gap by assessing lifestyle predictors of in vitro fertilization (IVF) outcomes in Romanian women.

Study design

Our pilot study included 35 participants who completed a first IVF cycle at a single infertility center. We evaluated individual self-reported lifestyle habits and behaviors as predictors of IVF outcomes, and employed principal component analysis (PCA) to characterize multiple lifestyle habits and behaviors into personal care product (PCP) use, and healthy diet and physical activity patterns as predictors of IVF outcomes.

Results

Our PCA analysis showed that greater use of PCPs was associated with lower probabilities of pregnancy (RR: 0.92, 95% CI [0.87-0.98]) and live birth (RR: 0.94, 95% CI [0.88-1.01]) while, the healthy dietary habits and physical activity were associated with a higher likelihood of pregnancy, although without statistical significance (RR: 1.10, 95% CI [0.93-1.30]).

Conclusions

In this pilot study we identified associations between IVF outcomes among Romanian women and certain lifestyle habits and behaviors including stress, diet and physical activity, and certain PCP use. We also estimated the joint effects of multiple lifestyle factors using PCA and found that PCP use, healthy dietary habits and physical activity were associated with IVF outcomes.

The effectiveness of reality therapy on sexual satisfaction and marital intimacy of infertile women

BACKGROUND

Infertility is one of the most important challenges in the modern life that can damage the sexual satisfaction and marital intimacy of couples. The present study was aimed to investigate the effectiveness of reality therapy on sexual satisfaction and marital intimacy of infertile women.

MATERIALS AND METHODS

This quasi-experimental study was conducted with a pretest-posttest design and follow-up. The statistical population was infertile women who were referred to Imam Sajjad Shahriyar Hospital in 2019-2020. 15 infertile women selected by purposive sampling and underwent reality therapy (8 sessions of 90 min). Data were collected using index sexual satisfaction (ISS) and marital intimacy questionnaire. Data analysis was performed using SPSS-24 software, analysis of variance with repeated measures and post hoc Bonferroni test.

RESULTS

The results of analysis of variance showed that there was a significant difference between the scores of sexual satisfaction and marital intimacy in posttest and follow-up stages compared to pretest (P < 0.05).

CONCLUSIONS

Based on the results, reality therapy can be used as an effective intervention to improvement sexual satisfaction and marital intimacy of infertile women.

The Association of Certain Seminal Phthalate Metabolites on Spermatozoa Apoptosis: An Exploratory Mediation Analysis via Sperm Protamine

Earlier studies have suggested that exposure to phthalates (PAEs) may induce spermatozoa apoptosis. Sperm protamine as a molecular biomarker during spermatozoa apoptotic processes may mediate the association between PAE exposure and spermatozoa apoptosis. This study aimed to explore whether sperm protamine mediates the association of PAE exposure with spermatozoa apoptosis. We determined sperm protamine levels, 8 PAE metabolite concentrations in seminal plasma, and 3 spermatozoa apoptosis parameters among 111 men from an infertility clinic. The associations of PAEs as individual chemicals and mixtures with sperm protamine were determined. The mediating roles of protamine in the associations between PAEs and spermatozoa apoptosis parameters were examined by mediation analysis. After adjusting for confounders, we observed positive correlations between seminal plasma concentrations of mono(2-ethylhexyl) phthalate (MEHP) and sperm protamine-1 and protamine ratio. Estimates comparing highest vs. lowest quartiles of MEHP concentration were 4.65% (95% CI: 1.47%, 7.82%) for protamine-1 and 25.86% (95% CI: 3.05%, 53.73%) for protamine ratio. The quantile g-computation models showed that the adjusted protamine-1 per quartile increase in PAE mixture was 9.42% (95% CI: 1.00, 20.92) with MEHP being the major contributor. Although the joint association between PAE mixture and protamine ratio was negligible, MEHP was still identified as the main contributor. Furthermore, we found that protamine-2 and protamine ratio levels in the highest quartiles exhibited a decrease of 43.45% (95% CI: 60.54%, -19.75%) and an increase of 122.55% (95% CI: 60.00%, 209.57%) in Annexin V⁺/PI^- spermatozoa relative to the lowest quartiles, respectively. Mediation analysis revealed that protamine ratio significantly mediated 55.6% of the association between MEHP and Annexin V⁺/PI^- spermatozoa elevation (5.13%; 95% CI: 0.04%, 10.52%). Our findings provided evidence that human exposure to PAEs was associated with increased protamine levels which may mediate the process of spermatozoa apoptosis.

Urinary phthalate metabolite concentrations are negatively associated with follicular fluid anti-müllerian hormone concentrations in women undergoing fertility treatment

Exposure to phthalates, endocrine-disrupting chemicals commonly used as plasticizers and in consumer products, has been associated with infertility and premature ovarian failure. Our objective was to investigate whether urinary phthalate metabolite concentrations were associated with pre-ovulatory follicular fluid (FF) anti-müllerian hormone (AMH) concentrations in women undergoing fertility treatment. This cross-sectional analysis included 138 women with urinary phthalate data available in the Environment and Reproductive Health (EARTH) Study (2010-2016) in whom FF AMH concentrations were quantified using a sandwich enzyme-linked immunosorbent assay (ELISA). We also quantified 8 phthalate metabolite concentrations using tandem mass spectrometry in 1-2 urine samples per cycle (total 331 urines) and calculated the cycle-specific geometric mean for each metabolite. We applied cluster-weighted generalized estimating equation models (CWGEE) to evaluate the associations of tertiles of urinary phthalate metabolite concentrations with log-transformed FF AMH concentrations adjusting for potential confounders. Study participants had median age of 34.0 years (IQR 32.0, 37.0), 83% were white, and median BMI of 23.1 kg/m² (IQR 21.2, 26.1). The following stimulation protocols were used: luteal phase agonist (70%), antagonist (14%), or flare (16%). Urinary concentrations of select phthalate metabolites were negatively associated with FF AMH. For example, women whose urinary mEOHP was in the lowest tertile (range 0.30-4.04 ng/ml) had an adjusted mean FF AMH of 0.72 ng/mL (95% CI = 0.36, 1.44), compared to women in the highest tertile (range 9.90-235), who had an adjusted mean of 0.24 ng/mL (95% CI = 0.12-0.48, p < 0.05). The negative association between urinary concentrations of certain phthalate metabolites with FF AMH concentrations may have implications for antral follicle recruitment and fertility treatment outcomes.

Female Reproductive Health and Exposure to Phthalates and Bisphenol A: A Cross Sectional Study

The xenoestrogenicity of some plasticisers (phthalates and bisphenol A) is documented in the literature and may pose a risk to female reproductive health. The aim of this study was to assess exposure to six phthalates. This was achieved by measuring their respective metabolites (mono-ethylphthalate (MEP); mono-n-butylphthalate (MnBP); mono-n-ottylphthalate (MnOP); and monobenzylphthalate (MBzP)), as well as the sum of two of the diethyl-hexyl phthalate metabolites-(∑DEHP) and bisphenol A (BPA) in a female population with infertility problems, and by conducting a correlation analysis between infertility factors, work activities, and lifestyle habits, in order to formulate a causal hypothesis. A cross-sectional epidemiological study was carried out and women under 43 years of age were recruited from an assisted reproduction technology (ART) center; the sample of 186 women was given a specific questionnaire and a spot urine sample was collected. Phthalate metabolites and urinary BPA were analyzed by HPLC/MS/MS. The results showed significantly higher mean values for MEP in women with recurrent pregnancy loss (RPL) (820.5 ± 1929.5 µg/g of creatinine) and idiopathic infertility (230.0 ± 794.2 µg/g of creatinine) than in women with other infertility factors (76.9 ± 171.8 µg/g of creatinine). Similarly, for MnOP levels, women with idiopathic infertility (2.95 ± 3.44 µg/g of creatinine) showed significantly higher values than women with the other infertility factors taken together (1.35 ± 2.05 µg/g of creatinine). Women with tubal factors of infertility, RPL, and endocrine dysfunctions show higher values of DEHP (p = 0.032). Considering occupations, women working in commerce showed more than twice as much urinary BPA levels (1.10 ± 0.48 µg/g of creatinine) compared to women working in other industries (0.45 ± 0.35 µg/g of creatinine). The presence of significantly higher values of certain phthalates, DEHP in particular, especially in women with RPL and idiopathic infertility, suggests a possible involvement of these compounds as competing factors in reproductive issues. The study of sources of exposure suggested that the working activity in trade, as a casher in particular, represents a major one for BPA (p = 0.015).

Update about the disrupting-effects of phthalates on the human reproductive system

Phthalate esters are synthetic chemicals used in the plastic industry as plasticizers and consumable products. According to United Nations, about 400 million tons of plastic are produced every year. In parallel with increased production, the concerns about its effects on human health have increased because phthalates are endocrine-disrupting compounds. Humans are continuously exposed to phthalates through different routes of exposure. Experimental data have associated the phthalates exposure to adverse effects on development and reproduction in women (e.g., earlier puberty, primary ovarian insufficiency, endometriosis, preterm birth, or in vitro fertilization) and men (e.g., anogenital distance, cryptorchidism, hypospadias, and changes in adult reproductive function) although there is no consensus. Therefore, one question arises: could the increase in infertility be related to phthalates exposure? To answer this question, we aimed to assess the disrupting-effects of phthalates on the human reproductive system. For this, we reviewed the current literature based on epidemiological and experimental data and experimental studies in humans. The phthalate effects were discussed in a separate mode for female and male reproductive systems. In summary, phthalates induce toxicity in the reproductive system and human development. The increased plastic production may be related to the increase in human infertility.