Prenatal exposure to an environmentally relevant phthalate mixture disrupts reproduction in F1 female mice

An exploratory study of volatile and semi-volatile organic compounds in PM2.5 atmospheric particles from an outdoor environment in Brazil

The development of methods for determining volatile and semi-volatile organic compounds in public spaces has become necessary to identify potential health and environmental risks. This study presents a practical methodology for sampling, extracting, detecting, and identifying these compounds in a vehicular traffic region in Belo Horizonte, Brazil. The methodology uses direct-immersion solid phase microextraction (DI-SPME) and static headspace (SHS) to extract SVOCs/VOCs. Comprehensive time-of-flight gas chromatography mass spectrometry (GC×GC/Q-TOFMS) and gas chromatography coupled to mass spectrometry (GC/MS) were used to detect and identify compounds. The analysed samples, collected with a high-volume sampler (Hi-Vol) with quartz filters and in which particulate matter (PM2.5) was retained, showed the presence of more than 200 compounds, both biogenic (natural origin) and anthropogenic (human origin). Regarding the distribution of chemical classes, aromatic compounds were predominantly found at 29.2%, followed by esters at 20.8%, non-aromatic hydrocarbons at 5.6%, and carboxylic acids at 9.4%. Static headspace gas chromatography (HS-GC) enabled the identification and quantification of 21 volatile compounds, including BETX, dichloromethane, chloroform, and naphthalene, which are currently regulated by the US Environmental Protection Agency (EPA).

Can Mammalian Reproductive Health Withstand Massive Exposure to Polystyrene Micro- and Nanoplastic Derivatives? A Systematic Review

The widespread use of plastics has increased environmental pollution by micro- and nanoplastics (MNPs), especially polystyrene micro- and nanoplastics (PS-MNPs). These particles are persistent, bioaccumulative, and linked to endocrine-disrupting toxicity, posing risks to reproductive health. This review examines the effects of PS-MNPs on mammalian reproductive systems, focusing on oxidative stress, inflammation, and hormonal imbalances. A comprehensive search in the Web of Science Core Collection, following PRISMA 2020 guidelines, identified studies on the impact of PS-MNPs on mammalian fertility, including oogenesis, spermatogenesis, and folliculogenesis. An analysis of 194 publications revealed significant reproductive harm, such as reduced ovarian size, depleted follicular reserves, increased apoptosis in somatic cells, and disrupted estrous cycles in females, along with impaired sperm quality and hormonal imbalances in males. These effects were linked to endocrine disruption, oxidative stress, and inflammation, leading to cellular and molecular damage. Further research is urgently needed to understand PS-MNPs toxicity mechanisms, develop interventions, and assess long-term reproductive health impacts across generations, highlighting the need to address these challenges given the growing environmental exposure.

Urinary phthalate metabolites associated with bone mineral density in adults: Data from the NHANES 2011-2018

Phthalates (PAEs) are common environmental endocrine disruptors and environmental bone poisons that can reduce bone mineral density (BMD). The purpose of this study is to investigate whether the concentration of PAE metabolites in urine is related to BMD in many parts of adult bones. We examined a series of cross-sectional data of male (n = 1835) and female (n = 1756) participants aged 18 to 59 years old in the National Health and Nutrition Examination Survey from 2011 to 2018 and measured urine PAE metabolites and dual-energy X-ray absorption to determine BMD (total body, lumbar spine, and pelvis). We used linear regression to test the correlation between a single phthalate biomarker and BMD. After adjusting all confounding variables, MEHP was positively correlated with BMD of total body, lumbar spine and pelvis, and BMD levels of the total body, lumbar spine and pelvis decreased with the increase of MECPP concentration. We used the restricted cubic spline function to test the nonlinear correlation between PAE biomarkers and BMD. The results show that urinary PAE metabolites have a nonlinear relationship with total body BMD, lumbar spine BMD, and pelvic BMD. With the increase in the PAE concentration, the BMD level first increased and then decreased, showing an inverted U-shaped trend (P < 0.05). Gender stratification also shows the same related trend. PAEs may be related to the BMD of adults. When the concentration of PAEs increases to a certain threshold, it will lead to a significant decrease in BMD.

Developmental exposure to environmentally relevant doses of phthalates alters the neural control of male and female reproduction in mice

The present study aims to analyze the effects of developmental exposure to phthalates at environmentally relevant doses on the neural control of male and female reproduction. For this purpose, C57Bl/6J mice were exposed to di-(2-ethylexyl) phthalate (DEHP) alone (5 or 50 μg/kg/d), or DEHP (5 μg/kg/d) in a phthalate mixture. Exposure through diet started 6 weeks before the first mating and lasted until weaning of litters from the second gestation (multiparous dams). Analyses of offspring born from multiparous dams exposed to DEHP alone or in a phthalate mixture showed that females experienced a delayed pubertal onset, and as adults they had prolonged estrous cyclicity and reduced Kiss1 expression in the preoptic area and mediobasal hypothalamus. Male littermates showed a reduced anogenital distance and delayed pubertal onset compared with controls. However, in adulthood the weight of androgen-sensitive organs and hypothalamic Kiss1 expression were unaffected, suggesting normal functioning of the male gonadotropic axis. Developmental exposure to DEHP alone or in a phthalate mixture reduced the ability of intact males and ovariectomized and hormonally primed females to attract a sexual partner and to express copulatory behaviors. In addition, females were unable to discriminate between male and female stimuli in the olfactory preference test. Social interaction was also impaired in females, while locomotor activity and anxiety-like behavior in both sexes were unaffected by the treatment. The sexual deficiencies were associated with reduced expression of the androgen receptor in the preoptic area and progesterone receptor in the mediobasal hypothalamus, the key regions involved in male and female sexual behavior, respectively. Thus, the neural structures controlling reproduction are vulnerable to developmental exposure to phthalates at environmentally relevant doses in male and female mice. Adult females had an impaired gonadotropic axis and showed more affected behaviors than adult males.

Prenatal exposure to an environmentally relevant phthalate mixture alters serum cytokine levels and inflammatory markers in the F1 mouse ovary

Phthalates are used as plasticizers and solvents in consumer products. Virtually 100% of the US population has measurable exposure levels to phthalates, however, the mechanisms by which prenatal exposure to phthalate mixtures affects reproductive health in the offspring remain unclear. Thus, this study tested the hypothesis that prenatal exposure to an environmentally relevant phthalate mixture promotes inflammation in F1 ovarian tissue. Pregnant CD-1 dams were dosed orally with vehicle control (corn oil) or phthalate mixture (20 μg/kg/d, 200 μg/kg/d, 200 mg/kg/d, 500 mg/kg/d). Pregnant dams delivered pups naturally and ovaries and sera from the F1 females were collected at postnatal day (PND) 21, PND 60, 3 mo, and 6 mo. Sera were used to measure levels of C-reactive protein (CRP). Ovaries and sera were used for cytokine array analysis. RNA was isolated from F1 ovaries and used to quantify expression of selected cytokine genes. Prenatal exposure to the mixture significantly increased the levels of CRP at 200 µg/kg/d on PND 21 compared with controls. The mixture altered 6 immune factors in sera at PND 21 and 33 immune factors in the ovary and sera at 6 mo compared with controls. The mixture increased ovarian expression of cytokines at PND 21 and decreased ovarian expression of cytokines at 6 mo compared with controls. These data suggest that prenatal exposure to a phthalate mixture interferes with the immune response in F1 female mice long after initial exposure.

Elucidating the mechanisms and mitigation strategies for six-phthalate-induced toxicity in male germ cells

Phthalate esters (PAEs) are primary plasticizers and endocrine-disrupting chemicals (EDCs) that are extensively used in numerous everyday consumer products. Although the adverse effects of single PAEs have been studied, our understanding of the effect of multiple phthalate exposure on male germ cell vitality remains limited. Therefore, this study aimed to investigate the collective effects of a mixture of PAEs (MP) comprising diethyl-, bis (2-ethylhexyl)-, dibutyl-, diisononyl-, diisobutyl-, and benzyl butyl-phthalates in the proportions of 35, 21, 15, 15, 8, and 5%, respectively, on differentiated male germ cells using GC-1 spermatogonia (spg) cells. As a mixture, MP substantially hindered GC-1 spg cell proliferation at 3.13 μg/mL, with a half-maximal inhibitory concentration of 16.9 μg/mL. Treatment with 25 μg/mL MP significantly induced reactive oxygen species generation and promoted apoptosis. Furthermore, MP activated autophagy and suppressed phosphorylation of phosphoinositide 3-kinase, protein kinase B, and mammalian target of rapamycin (mTOR). The triple inhibitor combination treatment comprising parthenolide, N-acetylcysteine, and 3-methyladenine effectively reversed MP-induced GC-1 spg cell proliferation inhibition, mitigated apoptosis and autophagy, and restored mTOR phosphorylation. This study is the first to elucidate the mechanism underlying MP-induced male germ cell toxicity and the restoration of male germ cell proliferation mediated by chemical inhibitors. Therefore, it provides valuable insights into the existing literature by proposing a combinatorial toxicity mitigation strategy to counteract male germ cell toxicity induced by various EDCs exposure.

Effects of maternal LPS and developmental exposure to an environmentally relevant phthalate mixture on neuron number in the rat medial prefrontal cortex

The brain is especially vulnerable to environmental influences during the perinatal period. While the effects of environmental factors are usually studied in isolation, it is more typical to be exposed to multiple influences during early development, necessitating study of synergistic actions on the developing brain. Both maternal infection and endocrine disrupting phthalates can decrease cell number in the medial prefrontal cortex (mPFC), a region critical for executive functioning. In the present study, groups of pregnant Long Evans rats were treated with either (1) 100 μg/kg (i.p.) lipopolysaccharide (LPS) on embryonic days 15 and 16 combined with a low-dose (1 mg/kg) phthalate mixture throughout gestation and the neonatal period, (2) LPS alone, (3) phthalates alone, or (4) neither phthalates nor LPS (control). Neurons and glial cells were stereologically quantified in the mPFC. The adult offspring previously exposed to LPS or phthalates alone had reduced mPFC neuron number in exposed males, but not females, while the combination treatment did not produce significant effects. In males, LPS alone also reduced the number of glia in the mPFC. Additionally, the combination of LPS and phthalates resulted in fewer pregnancies to term and decreased litter size. These results provide insight into how common environmental factors can interact to alter the developmental trajectory of the mPFC.

Impact of DEHP exposure on female reproductive health: Insights into uterine effects

Several endocrine disrupting compounds released from plastics, including polyfluoroalkyl substances, bisphenols, flame retardants, phthalates and others, are of great concern to human health due to their high toxicity. This review discusses the effects of di-(2-ethylhexyl) phthalate (DEHP), the most common member of the phthalate family, on female reproduction. In vitro and in vivo studies link DEHP exposure to impaired hypothalamic-pituitary-ovarian s (HPO) axis function, alteration of steroid-hormone levels and dysregulation of their receptors, and changes in uterine morphophysiology. In addition, high urinary DEPH levels have been associated with several reproductive disorders in women, including endometriosis, fibromyoma, fetal growth restriction and pregnancy loss. These data suggest that DEHP may be involved in the pathophysiology of various female reproductive diseases. Therefore, exposure to these compounds should be considered a concern in clinician surveillance practices for women at reproductive age and should be regulated to protect their health and that of their progeny.

Reproductive toxicity following in utero and lactational exposure to a human-relevant phthalate mixture in rats

This rodent (Wistar rats) study examined reproductive effects of in utero/lactational exposure to a mixture of 6 antiandrogenic phthalates (PMix): diisobutyl phthalate, di-n-butyl phthalate, diisopentyl phthalate, butylbenzyl phthalate, di-2-ethylhexyl phthalate, and diisononyl phthalate. The PMix was defined based on exposure data from pregnant women in Brazil. Experimental groups were established by extrapolating the estimated human dose to rats (0.1 mg/kg/day), followed by up to 3 additional doses corresponding to 5, 1000, and 5000 times the starting rat dose: 0 (control), 0.1, 0.5, 100, and 500 mg/kg/day. The fetal experiment assessed gestational exposure effects on fetal gonads, whereas the postnatal experiment evaluated reproductive parameters in males and females after in utero and lactational exposure. Prenatal exposure decreased fetal testicular testosterone production at 0.5 and 500 mg/kg/day. PMix 500 also reduced mRNA expression of steroidogenesis-related genes, upregulated transcript expression of the retinoic acid-degrading enzyme Cyp26b1, and increased multinucleated gonocytes incidence in fetal testes. Postnatal assessment revealed antiandrogenic effects at the highest dose, including reduced anogenital distance, nipple retention, and decreased weight of reproductive organs. Early puberty onset (preputial separation) was observed at the lowest dose in males. In contrast, females did not show significant changes in fetal and adult endpoints. Overall, the PMix recapitulated early and late male rat phthalate syndrome phenotypes at the highest dose, but also induced some subtle changes at lower doses, which warrant confirmation and mechanistic assessments. Our data support the use of epidemiologically defined mixtures for exposure risk assessments over traditional toxicological approaches.

Racial disparities affect the association between gestational urinary phthalate mixtures and infant genital measures

Background

Phthalates are ubiquitous anti-androgenic endocrine disrupting chemicals found in personal care products, medications, and many plastics. Studies have shown a racial disparity in phthalates exposure among U.S. women, which may also impact fetal development.

Methods

We conducted a prospective cohort study of gestational exposure to a phthalates mixture in a racially-diverse population to determine their association with genital development. Mid-gestation (18-22 weeks) urine was collected from 152 women who self-identified as non-Hispanic Black and 158 women who self-identified as non-Hispanic White in Charleston, South Carolina between 2011 and 2014. We measured eight phthalate monoester metabolites in urine using liquid chromatography tandem-mass spectrometry. Mid-gestational penile dimensions were measured using ultrasound and anogenital distances were measured postnatally. We used Bayesian kernel machine regression to estimate the associations among the mixture of phthalate metabolites and mid-gestation penile dimensions and postnatal anogenital distance measures among singleton male (n = 179) and female (n = 131) infants, adjusted for urinary specific gravity, maternal age, body mass index, education level, cigarette smoking, and gestational age at enrollment or birth weight z-score.

Results

We found a stronger association between greater phthalates and decreased anopenile distance among infants born to women who self-identified as Black. Mono (2-ethylhexyl) phthalate (MEHP) was the driving mixture component among Black women, and monobutyl phthalate (MBP) and monoethyl phthalate (MEP) were drivers among White women. We also identified a non-linear association between phthalates and lesser ultrasound penile volume among women who self-identified as Black with monoisobutyl phthalate (MiBP) and MBP being most important. We also found an association between greater phthalates and shorter anoclitoral distance among infants born to women who self-identified as Black, with MEP and monobenzyl phthalate (MBzP) contributing most to this association.

Conclusion

Our results suggest a disparity in the association between gestational exposure to a mixture of phthalates and fetal genital development among women who self-identified as Black compared to White.

Dietary exposure to an environmentally relevant phthalate mixture alters follicle dynamics, hormone levels, ovarian gene expression, and pituitary gene expression in female mice

Phthalates are chemicals ubiquitously used in industry. Individual phthalates have been found to adversely affect female reproduction; however, humans are exposed to a mixture of phthalates daily, primarily through ingestion. Previous studies show that exposure to an environmentally relevant mixture of phthalates (Mix) can affect female reproduction. Little research, however, has been conducted on the effects of short-term (1 month) and long-term (6 months) exposure to Mix on ovarian functions. Thus, this study tested the hypothesis that short-term and long-term exposure to Mix alters ovarian folliculogenesis, serum hormone concentrations, pituitary gene expression, and ovarian expression of genes involved in steroidogenesis, apoptosis, cell cycle regulation, and oxidative stress. Adult CD-1 female mice were exposed to vehicle control (corn oil) or Mix (0.15-1500 ppm) in the chow for 1 or 6 months. Exposure to Mix for 1 month increased the number of atretic follicles (0.15 ppm), altered ovarian gene expression (0.15 ppm, 1500 ppm), and decreased serum testosterone (1.5 ppm) compared to control. Exposure to Mix for 6 months increased serum follicle-stimulating hormone (FSH) (0.15 ppm), decreased serum luteinizing hormone (LH) (0.15 ppm, 1.5 ppm, and 1500 ppm), decreased serum estradiol (1500 ppm), altered pituitary gene expression (1500 ppm), increased the number (1500 ppm) and percentage (1.5 ppm and 1500 ppm) of primordial follicles, and decreased the percentage of preantral (1500 ppm) and antral (1.5 ppm and 1500 ppm) follicles compared to control. These data indicate that exposure to Mix can alter folliculogenesis, steroidogenesis, and gene expression in female mice.

Integrated transcriptome and proteome analysis indicates potential biomarkers of prostate cancer in offspring of pregnant rats exposed to a phthalate mixture during gestation and lactation

As the second leading cause of death for cancer among men worldwide, prostate cancer (PCa) prevention and detection remain a critical challenge. One aspect of PCa research is the identification of common environmental agents that may increase the risk of initiation and progression of PCa. Endocrine disrupting chemicals (EDCs) are strong candidates for risk factors, partially because they alter essential pathways for prostate gland development and oncogenesis. Phthalates correspond to a set of commercially used plasticizers that humans are exposed to ubiquitously. Here, we show that maternal exposure to a phthalate mixture interferes with the expression profile of mRNA and proteins in the ventral prostate of offspring and increases the susceptibility to prostate adenocarcinomas in aged animals. The data highlight Ubxn11, Aldoc, Kif5c, Tubb4a, Tubb3, Tubb2, Rab6b and Rab3b as differentially expressed targets in young and adult offspring descendants (PND22 and PND120). These phthalate-induced targets were enriched for pathways such as: dysregulation in post-translational protein modification (PTPM), cell homeostasis, HSP90 chaperone activity, gap junctions, and kinases. In addition, the Kif5c, Tubb3, Tubb2b and Tubb4a targets were enriched for impairment in cell cycle and GTPase activity. Furthermore, these targets showed strong relationships with 12 transcriptional factors (TF), which regulate the phosphorylation of eight protein kinases. The correlation of TF-kinases is associated with alterations in immune system, RAS/ErbB/VEGF/estrogen/HIF-1 signaling pathways, cellular senescence, cell cycle, autophagy, and apoptosis. Downregulation of KIF5C, TUBB3 and RAB6B targets is associated with poor prognosis in patients diagnosed with adenocarcinoma. Collectively, this integrative investigation establishes the post-transcriptional mechanisms in the prostate that are modulated by maternal exposure to phthalate mixture during gestation and lactation.

Exposure to a phthalate mixture disrupts ovulatory progesterone receptor signaling in human granulosa cells in vitro†

Exposure to phthalates disrupts ovarian function. However, limited studies have investigated the effects of phthalate mixtures on ovulation, especially in women. Human granulosa cells were used to test the hypothesis that exposure to a phthalate mixture (PHTmix) disrupts progesterone (P4)/progesterone receptor (PGR) signaling, which is a crucial pathway for ovulation. In addition, progestin and cyclic adenosine 3', 5'-monophosphate (cAMP) supplementation were tested as methods to circumvent phthalate toxicity. Granulosa cells from women undergoing in vitro fertilization were acclimated in culture to regain responsiveness to human chorionic gonadotropin (hCG; clinical luteinizing hormone analogue). Granulosa cells were treated with or without hCG, and with or without PHTmix (1-500 μg/ml; dimethylsulfoxide = vehicle control) for 0.5-36 h. In the supplementation experiments, cells were treated with or without R5020 (stable progestin), and with or without 8-Br-cAMP (stable cAMP analogue). Exposure to hCG + PHTmix decreased P4 levels and mRNA levels of steroidogenic factors when compared to hCG. This was accompanied by decreased mRNA levels of PGR and downstream P4/PGR ovulatory mediators (ADAM metallopeptidase with thrombospondin type 1 motif 1 (ADAMTS1), C-X-C motif chemokine receptor 4 (CXCR4), pentraxin 3 (PTX3), and regulator of G protein signaling 2 (RGS2)) in the hCG + PHTmix groups compared to hCG. Exposure to hCG + PHTmix 500 μg/ml decreased cAMP levels and protein kinase A activity compared to hCG. Supplementation with progestin in the hCG + PHTmix 500 μg/ml group did not rescue toxicity, while supplementation with cAMP restored PGR levels and downstream P4/PGR mediator levels to hCG levels. These findings suggest that phthalate mixture exposure inhibits P4/PGR signaling in human granulosa cells via decreased steroidogenesis, cAMP levels, and protein kinase A activity. Restored P4/PGR signaling with cAMP supplementation provides a potential cellular target for intervention of phthalate-induced ovulatory dysfunction in women.

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.

Chronic exposure to a mixture of phthalates shifts the white and brown adipose tissue phenotypes in female mice

Phthalates are endocrine-disrupting chemicals used in consumer products. Although phthalates are obesogens and affect metabolic function, it is unknown if chronic exposure for 6 months to a phthalate mixture alters adipose tissue phenotype in female mice. After vehicle or mixture exposure, white adipose tissue and brown adipose tissue (WAT and BAT) were analyzed for expression of adipogenesis, proliferation, angiogenesis, apoptosis, oxidative stress, inflammation, and collagen deposition markers. The mixture altered WAT morphology, leading to an increase in hyperplasia, blood vessel number, and expression of BAT markers (Adipoq and Fgf2) in WAT. The mixture increased the expression of the inflammatory markers, Il1β, Ccl2, and Ccl5, in WAT. The mixture also increased expression of the proapoptotic (Bax and Bcl2) and antiapoptotic (Bcl2l10) factors in WAT. The mixture increased expression of the antioxidant Gpx1 in WAT. The mixture changed BAT morphology by increasing adipocyte diameter, whitening area, and blood vessel number and decreased expression of the thermogenic markers Ucp1, Pgargc1a, and Adrb3. Furthermore, the mixture increased the expression of adipogenic markers Plin1 and Cebpa, increased mast cell number, and increased Il1β expression in BAT. The mixture also increased expression of the antioxidant markers Gpx and Nrf2 and the apoptotic marker Casp2 in BAT. Collectively, these data indicate that chronic exposure to a phthalate mixture alters WAT and BAT lipid metabolism phenotypes in female mice, leading to an apparent shift in their normal morphology. Following long-term exposure to a phthalate mixture, WAT presented BAT-like features and BAT presented WAT-like features.

Complex Mixtures and Multiple Stressors: Evaluating Combined Chemical Exposures and Cumulative Toxicity

The problem of chemical mixtures in the environment encompasses biological, analytical, logistical, and regulatory challenges, among others [...].

Reproductive toxicity of combined effects of endocrine disruptors on human reproduction

Confluence of environmental, genetic, and lifestyle variables is responsible for deterioration of human fecundity. Endocrine disruptors or endocrine disrupting chemicals (EDCs) may be found in a variety of foods, water, air, beverages, and tobacco smoke. It has been demonstrated in experimental investigations that a wide range of endocrine disrupting chemicals have negative effects on human reproductive function. However, evidence on the reproductive consequences of human exposure to endocrine disrupting chemicals is sparse and/or conflicting in the scientific literature. The combined toxicological assessment is a practical method for assessing the hazards of cocktails of chemicals, co-existing in the environment. The current review provides a comprehensive overview of studies emphasizing the combined toxicity of endocrine disrupting chemicals on human reproduction. Endocrine disrupting chemicals interact with each other to disrupt the different endocrine axes, resulting in severe gonadal dysfunctions. Transgenerational epigenetic effects have also been induced in germ cells, mostly through DNA methylation and epimutations. Similarly, after acute or chronic exposure to endocrine disrupting chemicals combinations, increased oxidative stress (OS), elevated antioxidant enzymatic activity, disrupted reproductive cycle, and reduced steroidogenesis are often reported consequences. The article also discusses the concentration addition (CA) and independent action (IA) prediction models, which reveal the importance of various synergistic actions of endocrine disrupting chemicals mixtures. More crucially, this evidence-based study addresses the research limitations and information gaps, as well as particularly presents the future research views on combined endocrine disrupting chemicals toxicity on human reproduction.

Long-term exposure to di(2-ethylhexyl) phthalate, diisononyl phthalate, and a mixture of phthalates alters estrous cyclicity and/or impairs gestational index and birth rate in mice

Phthalates are found in plastic food containers, medical plastics, and personal care products. However, the effects of long-term phthalate exposure on female reproduction are unknown. Thus, this study investigated the effects of long-term, dietary phthalate exposure on estrous cyclicity and fertility in female mice. Adult female CD-1 mice were fed chow containing vehicle control (corn oil) or 0.15-1500 ppm of di(2-ethylhexyl) phthalate (DEHP), diisononyl phthalate (DiNP), or a mixture of phthalates (Mix) containing DEHP, DiNP, benzyl butyl phthalate, di-n-butyl phthalate, diisobutyl phthalate, and diethyl phthalate. Measurements of urinary phthalate metabolites confirmed effective delivery of phthalates. Phthalate consumption for 11 months did not affect body weight compared to control. DEHP exposure at 0.15 ppm for 3 and 5 months increased the time that the mice spent in estrus and decreased the time the mice spent in metestrus/diestrus compared to control. DiNP exposure (0.15-1500 ppm) did not significantly affect time in estrus or metestrus/diestrus compared to control. Mix exposure at 0.15 and 1500 ppm for 3 months decreased the time the mice spent in metestrus/diestrus and increased the time the mice spent in estrus compared to control. DEHP (0.15-1500 ppm) or Mix (0.15-1500 ppm) exposure did not affect fertility-related indices compared to control. However, long-term DiNP exposure at 1500 ppm significantly reduced gestational index and birth rate compared to control. These data indicate that chronic dietary exposure to phthalates alters estrous cyclicity, and long-term exposure to DiNP reduces gestational index and birth rate in mice.

Associations between exposure to phthalates, phenols, and parabens with objective and subjective measures of sleep health among Mexican women in midlife: a cross-sectional and retrospective analysis

Endocrine-disrupting chemicals (EDCs) may impact sleep during the menopausal transition by altering sex hormones. However, these studies are scarce among Latin American women. This investigation utilized cross-sectional and retrospective data from midlife women enrolled in the Early Life Exposure in Mexico to Environmental Toxicants (ELEMENT) study to examine associations between exposure to EDCs (phthalates, phenols, and parabens) and sleep health measures. For cross-sectional analyses, single spot urine samples were collected between 2017-2019 from a pilot sample of women (N = 91) of midlife age to estimate the urinary concentration of individual phthalates, phenols, and parabens and to calculate the summary concentration of phthalate mixtures. Seven-day nightly sleep duration, midpoint, and fragmentation were obtained from wrist-actigraphy devices and estimated from the actigraphy data using a pruned dynamic programming algorithm. Self-reported poor sleep quality was assessed by one item from the Pittsburgh Sleep Quality Index (PSQI). We examined associations between urinary summary phthalate mixtures, phthalate metabolites, phenol, and paraben analytes with each sleep measure using linear or logistic (to compute odds of poor sleep quality only) regression models adjusted for specific gravity, age, and socioeconomic status. We ran similar regression models for retrospective analyses (N = 74), except that urine exposure biomarker data were collected in 2008 when women were 24-50 years old. At the 2017-2019 midlife visit, 38% reported poor sleep quality. Cross-sectionally, EDCs were associated with longer sleep duration, earlier sleep timing, and more fragmented sleep. For example, every 1-unit IQR increase in the phenol triclosan was associated with a 26.3 min per night (95% CI: 10.5, 42.2; P < 0.05) longer sleep duration and marginally associated with 0.2 decimal hours (95% CI: -0.4, 0.0; P < 0.10) earlier sleep midpoint; while every 1-unit IQR increase in the phthalate metabolite MEHP was associated with 1.1% higher sleep fragmentation (95% CI: 0.1, 2.1; P < 0.05). Retrospective study results generally mirrored cross-sectional results such that EDCs were linked to longer sleep duration, earlier sleep timing, and more fragmented sleep. EDCs were not significantly associated with odds of self-reported poor sleep quality. Results from cross-sectional and retrospective analyses revealed that higher exposure to EDCs was predictive of longer sleep duration, earlier sleep timing, and more fragmented sleep among midlife women.

Maternal exposure to di(2-ethylhexyl) phthalate (DEHP) causes multigenerational adverse effects on the uterus of F1 and F2 offspring rats

Phthalates are one of the ubiquitous chemicals found in day-to-day products like food packaging, children's toys, and other consumer commodities. There is rising concern that repeated exposure to phthalates during pregnancy and lactation could have long-term effects on maternal and fetal health. We hypothesize that exposure to DEHP during the developmental windows might affect the expression of molecules that regulate uterine function and that this effect would be passed on to further generations. Rat dams were treated with olive oil (vehicle) or DEHP (100 mg/kg b.wt./day) orally from gestational day 9 (GD 9) to the end of lactation (PND 21). F₀ maternal DEHP exposure resulted in multigenerational (F₁ and F₂) reproductive toxicity, as evidenced by an extended estrous cycle, decreased mating, fertility, and fecundity indices. Serum progesterone and estradiol levels were decreased and their cognate receptors (PR and ERα) in the uterus were decreased in the DEHP-exposed offspring rats. Further analysis of the expression of estrogen and progesterone regulatory genes such as Hox a11, VEGF A, Ihh, LIFR, EP4, PTCH, NR2F2, BMP2, and Wnt4 were reduced in the uteri of adult F₁ and F₂ generation rats born from DEHP-exposed F₀ dams. Decreased expression of these crucial proteins due to DEHP exposure may lead to defects in epithelial proliferation and secretion, uterine receptivity, and decidualization in the uteri of successive generations. This study showed that maternal DEHP exposure impairs the expression of molecules that regulate uterine function and this multigenerational effect is transmitted via maternal lineage.

Phthalates - A family of plasticizers, their health risks, phytotoxic effects, and microbial bioaugmentation approaches

Phthalates are a family of reprotoxicant compounds, predominantly used as a plasticizer to improve the flexibility and longevity of consumable plastic goods. After their use these plastic products find their way to the waste disposal sites where they leach out the hazardous phthalates present within them, into the surrounding environment, contaminating soil, groundwater resources, and the nearby water bodies. Subsequently, phthalates move into the living system through the food chain and exhibit the well-known phenomenon of biological magnification. Phthalates as a primary pollutant have been classified as 1B reprotoxicants and teratogens by different government authorities and they have thus imposed restrictions on their use. Nevertheless, the release of these compounds in the environment is unabated. Bioremediation has been suggested as one of the ways of mitigating this menace, but studies regarding the field applications of phthalate utilizing microbes for this purpose are limited. Through this review, we endeavor to make a deeper understanding of the cause and concern of the problem and to find out a possible solution to it. The review critically emphasizes the various aspects of phthalates toxicity, including their chemical nature, human health risks, phytoaccumulation and entry into the food chain, microbial role in phthalate degradation processes, and future challenges.

Medical devices as a source of phthalate exposure: a review of current knowledge and alternative solutions

Phthalates are a group of phthalic acid esters used as plasticisers in a large number of products to improve their flexibility, softness, and extensibility. Their wide use in medical devices, however, raises a lot of concern, as they can enter the organism and have toxic effects on human liver, thyroid, kidneys, lungs, reproductive, endocrine, nervous, and respiratory system and are associated with asthma, obesity, autism, and diabetes. The aim of this review is to summarise current knowledge about phthalate migration from medical devices during different medical procedures and possible impact on patient health. It also looks at alternative plasticisers with supposedly lower migration rates and safer profile. Not enough is known about which and how many phthalates make part of medical devices or about the health impacts of alternative plasticisers or their migration rates.

Endocrine-disruptor endpoints in the ovary and thyroid of adult female rats exposed to realistic doses of di-(2-ethylhexyl) phthalate

Di-(2-ethylhexyl) phthalate (DEHP) is the world's most widely used polyvinyl chloride (PVC) plasticizer and is used in virtually every category of flexible PVC. In fact, DEHP is extensively used in food cosmetics and medical packaging. It has become a serious problem in recent years. DEHP can be absorbed into the human body through the air, food, water, and skin. The current study involved intraperitoneal injection of DEHP dissolved in corn oil once daily for 21 consecutive days to investigate the effects of DEHP on the thyroid and the reproductive system in female rats. Results show that ovarian hormones (progesterone and estrogen) decreased significantly in the rats treated with DEHP compared to control. This result is supported by the alteration of folliculogenesis, the decrease of the follicles viability, and the apoptosis of the granulosa cells observed on histological sections of ovary and thyroid in female rats exposed to low doses of DEHP. Histopathological study revealed that DEHP could damage thyroid tissue and disrupt these functions. We also observed cellular damage, particularly in the liver cells, and a significant increase in biochemical parameters such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST) compared to the control group.

Black coffee mitigates diethyl phthalate disrupted folliculogenesis, reduced gonadotropins, and ovarian lesions in female albino mice

Phthalates are multifunctional compounds with extensive applications and emerging environmental pollutants. Due to their ubiquity in the environment and unavoidable exposure to humans, concerns have been voiced about public health dangers. This study was aimed to explore the diethyl phthalate (DEP) toxicity and the potential protective effect of black coffee in female Swiss albino mice. Four-week-old mice, weighing 12 ± 1 g were segregated into five groups (n = 10), designated as G-I (without any treatment), G-II (treated with corn oil), G-III (exposed to 1.5 mg/g body wt. (B.W.) DEP), G-IV (received 2 μg/g B.W coffee), and G-V (co-administrated with 1.5 mg/g DEP and 2 μg/g B.W coffee). Before dose administration, the coffee extract was assessed for its antioxidant potential through FRAP, TPC, and GC-MS analyses. Respective phthalates/coffee doses were administrated orally, once a day for 8 weeks consecutively starting from the prepubescent stage. After 56 days, mice were acclimated for 4 days then dissected. Morphological assessments showed an irregular shape of the ovaries in DEP-treated mice as compared to the control. The average bodyweight of DEP-intoxicated mice (p ≤ 0.05) increased notably against control, while DEP plus coffee group showed a regular gain in the average weight of mice. The gonado-somatic index showed non-significant variations among all groups. Micrometric studies showed that the diameter of secondary follicles (115 µm) in the ovaries of DEP-exposed mice (p ≤ 0.001) decreased significantly as compared to control (204 µm); conversely, follicular diameter in the coffee control group (248) increased significantly. Serum FSH and LH levels were significantly increased in DEP-exposed mice with a noteworthy decrease in estrogen level while hormonal levels of all other groups were comparable to control. Histological sections of DEP-exposed mice ovaries showed anatomical disruptions contrary to other groups, which were comparable with control. Antioxidant potential was checked in ovaries homogenates; FRAP values showed a notable decrease in DEP group in comparison with the control group, in contrast to G-V, when DEP was co-administrated with coffee. This study concluded that black coffee has protective effect, against DEP-instigated reproductive toxicity in Swiss albino female mice.

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.

Impact of Chemical Endocrine Disruptors and Hormone Modulators on the Endocrine System

There is growing concern regarding the health and safety issues of endocrine-disrupting chemicals (EDCs). Long-term exposure to EDCs has alarming adverse health effects through both hormone-direct and hormone-indirect pathways. Non-chemical agents, including physical agents such as artificial light, radiation, temperature, and stress exposure, are currently poorly investigated, even though they can seriously affect the endocrine system, by modulation of hormonal action. Several mechanisms have been suggested to explain the interference of EDCs with hormonal activity. However, difficulty in quantifying the exposure, low standardization of studies, and the presence of confounding factors do not allow the establishment of a causal relationship between endocrine disorders and exposure to specific toxic agents. In this review, we focus on recent findings on the effects of EDCs and hormone system modulators on the endocrine system, including the thyroid, parathyroid glands, adrenal steroidogenesis, beta-cell function, and male and female reproductive function.

Effects of Phthalate Mixtures on Ovarian Folliculogenesis and Steroidogenesis

The female reproductive system is dependent upon the health of the ovaries. The ovaries are responsible for regulating reproduction and endocrine function. Throughout a female's reproductive lifespan, the ovaries undergo continual structural changes that are crucial for the maturation of ovarian follicles and the production of sex steroid hormones. Phthalates are known to target the ovaries at critical time points and to disrupt normal reproductive function. The US population is constantly exposed to measurable levels of phthalates. Phthalates can also pass placental barriers and affect the developing offspring. Phthalates are frequently prevalent as mixtures; however, most previous studies have focused on the effects of single phthalates on the ovary and female reproduction. Thus, the effects of exposure to phthalate mixtures on ovarian function and the female reproductive system remain unclear. Following a brief introduction to the ovary and its major roles, this review covers what is currently known about the effects of phthalate mixtures on the ovary, focusing primarily on their effects on folliculogenesis and steroidogenesis. Furthermore, this review focuses on the effects of phthalate mixtures on female reproductive outcomes. Finally, this review emphasizes the need for future research on the effects of environmentally relevant phthalate mixtures on the ovary and female reproduction.

Early programming of reproductive health and fertility: novel neuroendocrine mechanisms and implications in reproductive medicine

BACKGROUND

According to the Developmental Origins of Health and Disease (DOHaD) hypothesis, environmental changes taking place during early maturational periods may alter normal development and predispose to the occurrence of diverse pathologies later in life. Indeed, adverse conditions during these critical developmental windows of high plasticity have been reported to alter the offspring developmental trajectory, causing permanent functional and structural perturbations that in the long term may enhance disease susceptibility. However, while solid evidence has documented that fluctuations in environmental factors, ranging from nutrient availability to chemicals, in early developmental stages (including the peri-conceptional period) have discernible programming effects that increase vulnerability to develop metabolic perturbations, the impact and eventual mechanisms involved, of such developmental alterations on the reproductive phenotype of offspring have received less attention.

OBJECTIVE AND RATIONALE

This review will summarize recent advances in basic and clinical research that support the concept of DOHaD in the context of the impact of nutritional and hormonal perturbations, occurring during the periconceptional, fetal and early postnatal stages, on different aspects of reproductive function in both sexes. Special emphasis will be given to the effects of early nutritional stress on the timing of puberty and adult gonadotropic function, and to address the underlying neuroendocrine pathways, with particular attention to involvement of the Kiss1 system in these reproductive perturbations. The implications of such phenomena in terms of reproductive medicine will also be considered.

SEARCH METHODS

A comprehensive MEDLINE search, using PubMed as main interface, of research articles and reviews, published mainly between 2006 and 2021, has been carried out. Search was implemented using multiple terms, focusing on clinical and preclinical data from DOHaD studies, addressing periconceptional, gestational and perinatal programming of reproduction. Selected studies addressing early programming of metabolic function have also been considered, when relevant.

OUTCOMES

A solid body of evidence, from clinical and preclinical studies, has documented the impact of nutritional and hormonal fluctuations during the periconceptional, prenatal and early postnatal periods on pubertal maturation, as well as adult gonadotropic function and fertility. Furthermore, exposure to environmental chemicals, such as bisphenol A, and maternal stress has been shown to negatively influence pubertal development and gonadotropic function in adulthood. The underlying neuroendocrine pathways and mechanisms involved have been also addressed, mainly by preclinical studies, which have identified an, as yet incomplete, array of molecular and neurohormonal effectors. These include, prominently, epigenetic regulatory mechanisms and the hypothalamic Kiss1 system, which likely contribute to the generation of reproductive alterations in conditions of early nutritional and/or metabolic stress. In addition to the Kiss1 system, other major hypothalamic regulators of GnRH neurosecretion, such as γ-aminobutyric acid and glutamate, may be targets of developmental programming.

WIDER IMPLICATIONS

This review addresses an underdeveloped area of reproductive biology and medicine that may help to improve our understanding of human reproductive disorders and stresses the importance, and eventual pathogenic impact, of early determinants of puberty, adult reproductive function and fertility.

Prenatal Exposure to an EDC Mixture, NeuroMix: Effects on Brain, Behavior, and Stress Responsiveness in Rats

Humans and wildlife are exposed to endocrine-disrupting chemicals (EDCs) throughout their lives. Environmental EDCs are implicated in a range of diseases/disorders with developmental origins, including neurodevelopment and behavior. EDCs are most often studied one by one; here, we assessed outcomes induced by a mixture designed to represent the real-world situation of multiple simultaneous exposures. The choice of EDCs, which we refer to as “NeuroMix,” was informed by evidence for neurobiological effects in single-compound studies and included bisphenols, phthalates, vinclozolin, and perfluorinated, polybrominated, and polychlorinated compounds. Pregnant Sprague Dawley rats were fed the NeuroMix or vehicle, and then offspring of both sexes were assessed for effects on postnatal development and behaviors and gene expression in the brain in adulthood. In order to determine whether early-life EDCs predisposed to subsequent vulnerability to postnatal life challenges, a subset of rats were also given a stress challenge in adolescence. Prenatal NeuroMix exposure decreased body weight and delayed puberty in males but not females. In adulthood, NeuroMix caused changes in anxiety-like, social, and mate preference behaviors only in females. Effects of stress were predominantly observed in males. Several interactions of NeuroMix and stress were found, especially for the mate preference behavior and gene expression in the brain. These findings provide novel insights into how two realistic environmental challenges lead to developmental and neurobehavioral deficits, both alone and in combination, in a sex-specific manner.

Maternal Perinatal Exposure to Dibutyl Phthalate Promotes Ovarian Dysfunction in Adult Female Offspring via Downregulation of TGF-β2 and TGF-β3

Maternal exposure to dibutyl phthalate (DBP) may result in ovarian dysfunction in female offspring. However, the underlying mechanisms remain elusive. Pregnant Sprague-Dawley rats were intraperitoneally injected with different doses of DBP, estradiol, and corn oil from gestational day 7 until the end of lactation. The reproductive characteristics, mRNA, and protein expression of ovaries for the adult female offspring were compared. KGN cells were cultured in vitro with DBP, estrogen receptor antagonist, or ALK-5 inhibitor. Genes, proteins, estradiol, and progesterone expressed by KGN, cell proliferation, and apoptosis were measured respectively. Maternal perinatal exposure to DBP induced prolonged estrous period, increased secondary follicles, significant decreased mRNA, and protein levels of TGF-β2, TGF-β3, and TGF-βRII in ovaries of the adult female offspring, but none difference for serum levels of sex hormones, ovarian TGF-β1, and estrogen receptor. The mRNA levels of LHR, FSHR, and CYP19a in ovaries were also decreased. DBP might decrease the mRNA of TGF-β2, TGF-β3, and TGF-βR II of KGN. DBP can inhibit the mRNA of CYP19 at 24 h, which might be blocked by the estrogen receptor antagonist, whose effects were attenuated at 48 h. DBP combined with FSH might time-dependently regulate the gene expression of TGF-βR II, inhibitory at 24 h, but stimulative at 48 h, which could be blocked by the ALK5 inhibitor. However, the protein expressed by KGN was not influenced by DBP. DBP stimulated the proliferation of KGN at 24 h, which could be blocked by estrogen receptor antagonist, but attenuated at 48 h. The progesterone in culture medium secreted by KGN was decreased by DBP at 24 h. Maternal perinatal exposure to DBP induced decreased gene expression of TGF-β signaling and functional proteins in ovaries of the adult female offspring. Molecular cross-talk between estrogen receptor and TGF-β signaling pathway may play role in the mechanism of granulosa dysfunction induced by DBP.

Prenatal exposure to an environmentally relevant phthalate mixture alters ovarian steroidogenesis and folliculogenesis in the F1 generation of adult female mice

Phthalates are a family of chemicals that can be found in plastic and personal care products used by consumers every day and they are known endocrine disrupting chemicals that can disrupt female reproduction. In previous studies, an environmentally relevant phthalate mixture was shown to affect female reproduction in a transgenerational manner. However, limited information was available on the effect of phthalate mixtures on ovarian steroidogenesis and folliculogenesis. Ovarian steroidogenesis is important for producing hormones needed for reproduction and ovarian regulation, and folliculogenesis is essential for the development of ovarian follicles and successful fertility. Thus, this study tested the hypothesis that prenatal exposure to an environmentally relevant phthalate mixture adversely affects ovarian steroidogenesis and folliculogenesis in the F1 generation of adult female mice. Pregnant dams (F0 generation) were orally dosed with vehicle control or a phthalate mixture (20 μg/kg/day-500 mg/kg/day) daily from gestational day 10 to birth, and the adult F1 females were the offspring of the dosed dams. The ovaries of the F1 generation were collected at postnatal day 60. One ovary was used for histological examination of the numbers and percent of different follicle types. The other ovary was used to measure expression of theca and granulosa cell enzymes. Additionally, sera were collected for measuring hormone levels. The results indicate that prenatal exposure to the phthalate mixture decreases hormone levels and gene expression, alters the transitioning of follicle types, and leads to a higher incidence of atresia in the F1 generation offspring.

Prenatal exposure to a mixture of phthalates accelerates the age-related decline in reproductive capacity but may not affect direct biomarkers of ovarian aging in the F1 generation of female mice

Phthalates are used in many consumer products, leading to daily human exposure. Although many studies focus on single phthalates, humans are exposed to mixtures of phthalates. Our laboratory created a phthalate mixture consisting of six different phthalates and found that it negatively affected female reproduction and accelerated some biomarkers of reproductive aging. However, it was unknown if prenatal exposure to the mixture accelerates the natural decline in reproductive capacity and ovarian aging in mice. Therefore, we tested the hypothesis that prenatal exposure to a phthalate mixture accelerates the age-related decline in reproductive capacity and biomarkers of ovarian aging in the F1 generation of mice. Pregnant CD-1 dams were orally dosed with control or phthalate mixture (20 µg/kg/day-200 mg/kg/day) daily from gestational day 10-birth. The F1 female pups were aged to 11-13 months, and then estrous cyclicity and breeding trials were conducted at 11 and 13 months. Ovaries were collected from the F1 females at 13 months to examine biomarkers of ovarian aging. Prenatal exposure to the phthalate mixture decreased the time the F1 females spent in proestrus and the ability of the F1 females to give birth at 11 and 13 months of age compared to control. In contrast, prenatal exposure to the mixture did not affect biomarkers of direct aging of the ovary in the F1 generation. Collectively, our data show that prenatal phthalate mixture exposure accelerates the natural age-related decline in reproductive capacity but may not affect some biomarkers of ovarian aging in the F1 generation.

Perinatal phthalate exposure increases developmental apoptosis in the rat medial prefrontal cortex

Phthalates are a class of endocrine disruptors found in a variety of consumer goods, and offspring can be exposed to these compounds during gestation and lactation. Our laboratory has found that perinatal exposure to an environmentally relevant mixture of phthalates resulted in a decrease in cognitive flexibility and in neuron number in the adult rat medial prefrontal cortex (mPFC). Here, we examine effects of phthalate treatment on prenatal cellular proliferation and perinatal apoptosis in the mPFC. To examine the phthalate effects on cellular proliferation, dams consumed 0, 1, or 5 mg/kg of the phthalate mixture daily from embryonic day 2 (E2) through the day of birth (P0), and on E16 and E17, they were injected with BrdU. The mPFC of offspring was analyzed on P5 and showed a decrease in labelled cells in the phthalate exposed groups. To examine whether changes in BrdU density observed on P5 were due to altered cell survival, cell death was measured on E18, P0, and P5 using a TUNEL assay in a separate cohort of prenatally exposed offspring. There was an increase in TUNEL labelled cells at E18 in the phthalate exposed groups. In the final experiment, dams consumed the phthalate mixture from E2 through P10, at which time mPFC tissue was stained with TUNEL. Phthalate treated subjects showed a higher density of apoptotic cells at P10. These results indicate both pre- and postnatal phthalate exposure increases apoptosis in the male and female rat mPFC. While the impact of phthalates on proliferation cannot be ruled out, these data do not allow for definitive conclusions.

Early postnatal exposure to di(2-ethylhexyl) phthalate causes sex-specific disruption of gonadal development in pigs

Di(2-ethylhexyl) phthalate (DEHP) is a chemical commonly used as a plasticizer to render polyvinyl chloride products more durable and flexible. Although exposure to DEHP has raised many health concerns due to the identification of DEHP as an endocrine disruptor, it is still used in consumer products, including polyvinyl chloride plastics, medical tubing, car interiors, and children's toys. To investigate the impact of early life exposure to DEHP on the ovary and testes, newborn piglets were orally dosed with DEHP (20 or 200 mg/kg/day) or vehicle control (tocopherol-stripped corn oil) for 21 days. Following treatment, ovaries, testes, and sera were harvested for histological assessment and measurement of steroid hormone levels. In male piglets, progesterone and pregnenolone levels were significantly lower in both treatment groups compared to control, whereas in female piglets, progesterone was significantly higher in the 20 mg group compared to control, indicating sex-specific effects in a non-monotonic manner. Follicle numbers and gene expression of steroidogenic enzymes and apoptotic factors were not altered in treated ovaries compared to controls. In DEHP-treated testes, germ cell migration was impaired and germ cell death was significantly increased compared to controls. Overall, the results of this study suggest that neonatal exposure to DEHP in pigs leads to sex-specific disruption of the reproductive system.

Subacute Exposure to an Environmentally Relevant Dose of Di-(2-ethylhexyl) Phthalate during Gestation Alters the Cecal Microbiome, but Not Pregnancy Outcomes in Mice

Di-2-ethylhexyl phthalate (DEHP) is a plasticizer commonly found in polyvinyl chloride, medical equipment, and food packaging. DEHP has been shown to target the reproductive system and alter the gut microbiome in humans and experimental animals. However, very little is known about the impact of DEHP-induced microbiome changes and its effects during pregnancy. Thus, the objective of this study was to investigate the effects of DEHP exposure during pregnancy on the cecal microbiome and pregnancy outcomes. Specifically, this study tested the hypothesis that subacute exposure to DEHP during pregnancy alters the cecal microbiome in pregnant mice, leading to changes in birth outcomes. To test this hypothesis, pregnant dams were orally exposed to corn oil vehicle or 20 µg/kg/day DEHP for 10 days and euthanized 21 days after their last dose. Cecal contents were collected for 16S Illumina and shotgun metagenomic sequencing. Fertility studies were also conducted to examine whether DEHP exposure impacted birth outcomes. Subacute exposure to environmentally relevant doses of DEHP in pregnant dams significantly increased alpha diversity and significantly altered beta diversity. Furthermore, DEHP exposure during pregnancy significantly increased the relative abundance of Bacteroidetes and decreased the relative abundance of Firmicutes and Deferribacteres compared with controls. The affected taxonomic families included Deferribacteraceae, Lachnospiraceae, and Mucisprillum. In addition to changes in the gut microbiota, DEHP exposure significantly altered 14 functional pathways compared with the control. Finally, DEHP exposure did not significantly impact the fertility and birth outcomes compared with the control. Collectively, these data indicate that DEHP exposure during pregnancy shifts the cecal microbiome, but the shifts do not impact fertility and birth outcomes.

In utero exposure to phthalates and reproductive toxicity in rodents

Phthalates, widely used as plasticizers, are contained in many everyday products. Human biomonitoring studies detect their presence in biological fluids of a large part of the population worldwide. Maternal exposure during pregnancy has been related with aberrations in the reproductive growth of male infants. Rodent studies show that gestational exposure to single phthalates elicits reproductive toxicity in both sexes. Early aberrations include inhibition of gonadal sex determining gene expression and steroidogenesis, histopathology, and disturbed gametogenesis, leading later in life to dysfunctions in sperm production and oocyte reserves. Animal studies of in utero exposure to mixtures of phthalates, better mimicking human exposures, revealed analogous reproductive dysfunctions with the single compounds, but also indicated the combined actions and cumulative effects exerted by these chemicals. Further understanding the underlying mechanisms and the species differences in phthalate-induced reproductive toxicity will help to improve the risk assessment for human exposure to these toxicants.

Prenatal exposure to a mixture of different phthalates increases the risk of mammary carcinogenesis in F1 female offspring

Phthalates metabolites have been detected in the urine of pregnant and breastfeeding women. Thus, this study evaluated the adverse effects of maternal exposure to a mixture of six phthalates (Pth mix) on the mammary gland development and carcinogenesis in F1 female offspring. Pregnant female Sprague-Dawley rats were exposed daily to vehicle or Pth mix (35.22% diethyl-phthalate, 21.03% di-(2-ethylhexyl)-phthalate, 14.91% dibutyl-phthalate, 15.10% diisononyl-phthalate, 8.61% diisobutyl-phthalate, and 5.13% benzylbutyl-phthalate) by gavage at 20 μg/kg, 200 μg/kg or 200 mg/kg during gestational day 10 (GD 10) to postnatal day 21 (PND 21). After weaning (PND 22), some female offspring were euthanized for mammary gland analyses while other females received a single dose of N-methyl-N-nitrosourea (MNU, 50 mg/kg) or vehicle and then tumor incidence and multiplicity were recorded until PND 180. Maternal Pth mix exposure increased the number of Ki-67 and progesterone receptor-positive epithelial cells in the mammary gland from Pth mix 200 at μg/kg and 200 mg/kg groups. In addition, tumor incidence and mean number were higher only in Pth mix at 200 mg/kg when compared to the vehicle-treated group, and percentage of tumor-free animals was lower in Pth mix at 200 μg/kg and 200 mg/kg groups. The findings indicate that perinatal Pth mixture exposure increased susceptibility to MNU-induced mammary carcinogenesis in adult F1 female offspring.

Mono-n-Butyl Phthalate Distributes to the Mouse Ovary and Liver and Alters the Expression of Phthalate-Metabolizing Enzymes in Both Tissues

Humans are exposed to phthalates daily via items such as personal care products and medications. Reproductive toxicity has been documented in mice exposed to di-n-butyl phthalate (DBP); however, quantitative evidence of its metabolite, mono-n-butyl phthalate (MBP), reaching the mouse ovary and its effects on hepatic and ovarian biotransformation enzymes in treated mice is still lacking. Liquid chromatography/tandem mass spectrometry (LC-MS/MS) was employed to quantify MBP levels in liver, serum, and ovary from mice treated with a single or repeated exposure to the parent compound, DBP. Adult CD-1 females were pipet fed once or for 10 days with vehicle (tocopherol-stripped corn oil) or DBP at 1, 10, and 1000 mg/kg/day. Tissues and serum were collected at 2, 6, 12, and 24 h after the single or final dose and subjected to LC-MS/MS. Ovaries and livers were processed for qPCR analysis of selected phthalate-associated biotransformation enzymes. Regardless of duration of exposure (single vs repeated), MBP was detected in the tissues of DBP-treated mice. In single dose mice, MBP levels peaked at ≤6 h and fell close to background levels by 24 h post-exposure. Following the last repeated dose, MBP levels peaked at ≤2 h and fell to background levels by 12 h. Hepatic and ovarian expression of Lpl, Aldh1a1, Adh1, Ugt1a6a, and Cyp1b1 were altered in DBP-treated mice in a time- and dose-specific manner. These findings confirm that MBP reaches the mouse liver and ovary after oral exposure to DBP and influences the expression of hepatic and ovarian phthalate-associated biotransformation enzymes.

Is Maternal Use of Paracetamol during Pregnancy Associated with Anogenital Distance in Male Newborns? The Results from the NELA Birth Cohort

Paracetamol is the one of the most commonly used medications during pregnancy. However, its potential antiandrogenic effect has been suggested. The objective of this study was to evaluate associations between maternal paracetamol use during pregnancy and anogenital distance (AGD) in male newborns from a Spanish birth cohort. The study included two hundred and seventy-seven mother-male child pairs with self-reported paracetamol use and frequency during each trimester of pregnancy. AGD measurements were taken employing standardized methods. The associations between maternal paracetamol use and AGD measures were evaluated using linear regression models, adjusting for potential confounders and covariates. Overall, 61.7% of pregnant women consumed paracetamol at any time of pregnancy with an average of 9.43 (SD = 15.33) days throughout pregnancy. No associations between the maternal use of paracetamol or its frequency and AGD measures among different trimesters or during the whole pregnancy were found in the adjusted final models. A non-differential misclassification error may have occurred—the recall of paracetamol intake independent of AGD measurements—introducing bias towards the null hypothesis. Nevertheless, the current evidence suggests that paracetamol might have a potential antiandrogenic effect especially in the early stages of fetal development. Thus, it would be highly recommendable to pursue further studies to elucidate the potential effects of paracetamol in human perinatal health and its use among pregnant women.

Review of endocrine disruptors on male and female reproductive systems

Endocrine disruptors (EDs) interfere with different hormonal and metabolic processes and disrupt the development of organs and tissues, as well as the reproductive system. In toxicology research, various animal models have been utilized to compare and characterize the effects of EDs. We reviewed studies assessing the effect of ED exposure in humans, zebrafish, and mouse models and the adverse effects of EDs on male and female reproductive systems. This review outlines the distinctive morphological characteristics, as well as gene expression, factors, and mechanisms that are known to occur in response to EDs. In each animal model, disturbances in the reproductive system were associated with certain factors of apoptosis, the hypothalamic-pituitary-gonadal axis, estrogen receptor pathway-induced meiotic disruption, and steroidogenesis. The effects of bisphenol A, phthalate, and 17α-ethinylestradiol have been investigated in animal models, each providing supporting outcomes and elaborating the key regulators of male and female reproductive systems.

Combined toxicity of endocrine-disrupting chemicals: A review

The combined toxicological assessment provides a realistic approach for hazard evaluation of chemical cocktails that co-existed in the environment. This review provides a holistic insight into the studies highlighting the mixture toxicity of the endocrine-disrupting chemicals (EDCs), especially focusing on the screening of biochemical pathways and other toxicogenetic endpoints. Reviewed literature showed that numerous multiplexed toxicogenomic techniques were applied to determine reproductive effects in vertebrates, but limited studies were found in non-mammalian species after mixture chemical exposure. Further, we found that the experimental design and concentration selection are the two important parameters in mixture toxicity studies that should be time- and cost-effective, highly precise, and environmentally relevant. A summary of EDC mixtures affecting the thyroid axis, estrogen axis, androgen axis, growth stress, and immune system via in vivo bioassays was also presented. It is interesting to mention that majority of estrogenic effects of the mixtures were sex-dependent, particularly observed in male fish as compared to female fish. Further, the androgen axis was perturbed with serious malformations in male rat testis (epididymal or gubernacular lesions, and deciduous spermatids). Also, transgenerational epigenetic effects were promoted in the F₃ and F₄ generations in the form of DNA methylation epimutations in sperm, increasing polycystic ovaries and reducing the offspring. Similarly, increased oxidative stress, high antioxidant enzymatic activities, disturbed estrous cycle, and decreased steroidogenesis were the commonly found effects after acute or chronic exposure to EDC mixtures. Importantly, the concentration addition (CA) and independent action (IA) models became more prevalent and suitable predictive models to unveil the prominence of synergistic estrogenic and anti-androgenic effects of chemical mixtures. More importantly, this review encompasses the research challenges and gaps in the existing knowledge and specific future research perspectives on combined toxicity.

Praegnatio Perturbatio-Impact of Endocrine-Disrupting Chemicals

The burden of adverse pregnancy outcomes such as preterm birth and low birth weight is considerable across the world. Several risk factors for adverse pregnancy outcomes have been identified. One risk factor for adverse pregnancy outcomes receiving considerable attention in recent years is gestational exposure to endocrine-disrupting chemicals (EDCs). Humans are exposed to a multitude of environmental chemicals with known endocrine-disrupting properties, and evidence suggests exposure to these EDCs have the potential to disrupt the maternal-fetal environment culminating in adverse pregnancy and birth outcomes. This review addresses the impact of maternal and fetal exposure to environmental EDCs of natural and man-made chemicals in disrupting the maternal-fetal milieu in human leading to adverse pregnancy and birth outcomes-a risk factor for adult-onset noncommunicable diseases, the role lifestyle and environmental factors play in mitigating or amplifying the effects of EDCs, the underlying mechanisms and mediators involved, and the research directions on which to focus future investigations to help alleviate the adverse effects of EDC exposure.

Detrimental effects induced by diisononyl phthalate on development and behavior of Drosophila larva and potential mechanisms

Diisononyl phthalate (DINP) as one of the most commonly used phthalates, has been found in various environmental samples and is considered to have potential risks to ecosystem. Till now, DINP has no clear effect consensus on insects from development to behavior and even mechanisms. Here, Drosophila melanogaster was selected as model organisms and the toxic effects of DINP (0.1%, 0.2%, 0.5% and 1.0%) (v/v) on its metamorphosis, crawling behavior, intestinal cells and cellular redox balance were investigated. During metamorphosis process, lower hatching rate, longer development time, lighter body weight and malformation were observed at high concentration groups. The crawling ability of larvae was severely inhibited by DINP and the movement distance was drastically reduced. DINP could cause severe damage to the larval intestinal cells in the dose-dependent and time-dependent manners. DINP was found to induce redox imbalance with activities of two important antioxidant enzymes (catalase (CAT) and superoxide dismutase (SOD)) increasing, and reactive oxygen species (ROS) level fluctuation in larvae. Our findings provide theoretical basis and data support for scientific management of DINP to reduce ecological risk.

Effects of Continuous In Utero Low- and Medium-Dose-Rate Gamma-Ray Exposure on Fetal Germ Cells

The effects of radiation exposure on germ cells and the gonads have been well studied at acute high-dose exposures, but the effects of chronic low-dose-rate (LDR) irradiation, particularly relevant for radiation protection, on germ cells and the gonads are largely unknown. Our previous study revealed that chronic exposure of mice to medium-dose-rate (MDR, 200 or 400 mGy/day) gamma-rays in utero for the entire gestation period (18 days) induced only a mild degree of general growth retardation, but with very drastic effects on the gonads and germ cells. In the current study, we further investigated the histomorphological changes in the gonads and the number of germ cells from gestation day (GD) 18 fetuses irradiated with MDR throughout the entire gestation period. The germ cells in the testes and ovaries of the MDR-irradiated fetuses were almost obliterated. Gestation day 18 fetuses exposed to LDR (20 mGy/day) radiation for the entire gestation period showed decreases in the number of the germ cells, which were not statistically significant or only marginally significant at most. Further investigations on the effects of LDR irradiation in utero using more sensitive methods are necessary.

Toxicological Assessment of Oral Co-Exposure to Bisphenol A (BPA) and Bis(2-ethylhexyl) Phthalate (DEHP) in Juvenile Rats at Environmentally Relevant Dose Levels: Evaluation of the Synergic, Additive or Antagonistic Effects

BACKGROUND

The general population (including children) is exposed to chemical mixtures. Plasticizers such as Bisphenol A (BPA) and Phthalates (mainly Bis(2-ethylhexyl) phthalate-DEHP) are widespread contaminants classified as endocrine disrupters which share some toxicological profiles and coexist in food and environment.

METHODS

To identify hazards of DEHP and BPA mixtures, the juvenile toxicity test-where rodents are in peripubertal phase of development, resembling childhood-was selected using exposure data from biomonitoring study in children. Biological activity and potential enhanced and/or reduced toxicological effects of mixtures due to common mechanisms were studied, considering endpoints of metabolic, endocrine and reproductive systems. The degree of synergy or antagonism was evaluated by synergy score calculation, using present data and results from the single compound individually administered.

RESULTS

In metabolic system, synergic interaction predominates in female and additive in male rats; in the reproductive and endocrine systems, the co-exposure of BPA and DEHP showed interactions mainly of antagonism type.

CONCLUSIONS

The present approach allows to evaluate, for all the endpoints considered, the type of interaction between contaminants relevant for human health. Although the mode of action and biological activities of the mixtures are not completely addressed, it can be of paramount usefulness to support a more reliable risk assessment.

Exposure to phthalates: germline dysfunction and aneuploidy

Epidemiological studies continue to reveal the enduring impact of exposures to environmental chemicals on human physiology, including our reproductive health. Phthalates, a well characterized class of endocrine disrupting chemicals and commonly utilized plasticizers, are among one of the many toxicants ubiquitously present in our environment. Phthalate exposure has been linked to increases in the rate of human aneuploidy, a phenomenon that is detected in 0.3% of livebirths resulting in genetic disorders including trisomy 21, approximately 4% of stillbirths, and over 35% of miscarriages. Here we review recent epidemiological and experimental studies that have examined the role that phthalates play in germline dysfunction, including increases in apoptosis, oxidative stress, DNA damage, and impaired genomic integrity, resulting in aneuploidy. We will further discuss subject variability, as it relates to diet and polymorphisms, and the sexual dimorphic effects of phthalate exposure, as it relates to sex-specific targets. Lastly, we discuss some of the conserved effects of phthalate exposure across humans, mammalian models and nonmammalian model organisms, highlighting the importance of using model organisms to our advantage for chemical risk assessment and unveiling potential mechanisms that underlie phthalate-induced reproductive health issues across species.

Endocrine Disruptors Acting on Estrogen and Androgen Pathways Cause Reproductive Disorders through Multiple Mechanisms: A Review

Increasing contamination of the environment by toxic compounds such as endocrine disrupting chemicals (EDCs) is one of the major causes of reproductive defects in both sexes. Estrogen/androgen pathways are of utmost importance in gonadal development, determination of secondary sex characteristics and gametogenesis. Most of the EDCs mediate their action through respective receptors and/or downstream signaling. The purpose of this review is to highlight the mechanism by which EDCs can trigger antagonistic or agonistic response, acting through estrogen/androgen receptors causing reproductive defects that lead to infertility. In vitro, in vivo and in silico studies focusing on the impact of EDCs on estrogen/androgen pathways and related proteins published in the last decade were considered for the review. PUBMED and PUBCHEM were used for literature search. EDCs can bind to estrogen receptors (ERα and ERβ) and androgen receptors or activate alternative receptors such as G protein-coupled receptors (GPCR), GPR30, estrogen-related receptor (ERRγ) to activate estrogen signaling via downstream kinases. Bisphenol A, dichlorodiphenyltrichloroethane, dichlorodiphenyldichloroethylene, polychlorinated biphenyls and phthalates are major toxicants that interfere with the normal estrogen/androgen pathways leading to infertility in both sexes through many ways, including DNA damage in spermatozoids, altered methylation pattern, histone modifications and miRNA expression.

Endocrine disrupting chemicals and reproductive disorders in women, men, and animal models

This chapter covers the known effects of endocrine disrupting chemicals (EDCs) on reproductive disorders. The EDCs represented are highly studied, including plasticizers (bisphenols and phthalates), chemicals in personal care products (parabens), persistent environmental contaminants (polychlorinated biphenyls), and chemicals in pesticides or herbicides. Both female and male reproductive disorders are reviewed in the chapter. Female disorders include infertility/subfertility, irregular reproductive cycles, early menopause, premature ovarian insufficiency, polycystic ovarian syndrome, endometriosis, and uterine fibroids. Male disorders include infertility/subfertility, cryptorchidism, and hypospadias. Findings from both human and animal studies are represented.

Hypothetical roadmap towards endometriosis: prenatal endocrine-disrupting chemical pollutant exposure, anogenital distance, gut-genital microbiota and subclinical infections

BACKGROUND

Endometriosis is a gynaecological hormone-dependent disorder that is defined by histological lesions generated by the growth of endometrial-like tissue out of the uterus cavity, most commonly engrafted within the peritoneal cavity, although these lesions can also be located in distant organs. Endometriosis affects ~10% of women of reproductive age, frequently producing severe and, sometimes, incapacitating symptoms, including chronic pelvic pain, dysmenorrhea and dyspareunia, among others. Furthermore, endometriosis causes infertility in ~30% of affected women. Despite intense research on the mechanisms involved in the initial development and later progression of endometriosis, many questions remain unanswered and its aetiology remains unknown. Recent studies have demonstrated the critical role played by the relationship between the microbiome and mucosal immunology in preventing sexually transmitted diseases (HIV), infertility and several gynaecologic diseases.

OBJECTIVE AND RATIONALE

In this review, we sought to respond to the main research question related to the aetiology of endometriosis. We provide a model pointing out several risk factors that could explain the development of endometriosis. The hypothesis arises from bringing together current findings from large distinct areas, linking high prenatal exposure to environmental endocrine-disrupting chemicals with a short anogenital distance, female genital tract contamination with the faecal microbiota and the active role of genital subclinical microbial infections in the development and clinical progression of endometriosis.

SEARCH METHODS

We performed a search of the scientific literature published until 2019 in the PubMed database. The search strategy included the following keywords in various combinations: endometriosis, anogenital distance, chemical pollutants, endocrine-disrupting chemicals, prenatal exposure to endocrine-disrupting chemicals, the microbiome of the female reproductive tract, microbiota and genital tract, bacterial vaginosis, endometritis, oestrogens and microbiota and microbiota-immune system interactions.

OUTCOMES

On searching the corresponding bibliography, we found frequent associations between environmental endocrine-disrupting chemicals and endometriosis risk. Likewise, recent evidence and hypotheses have suggested the active role of genital subclinical microbial infections in the development and clinical progression of endometriosis. Hence, we can envisage a direct relationship between higher prenatal exposure to oestrogens or estrogenic endocrine-disrupting compounds (phthalates, bisphenols, organochlorine pesticides and others) and a shorter anogenital distance, which could favour frequent postnatal episodes of faecal microbiota contamination of the vulva and vagina, producing cervicovaginal microbiota dysbiosis. This relationship would disrupt local antimicrobial defences, subverting the homeostasis state and inducing a subclinical inflammatory response that could evolve into a sustained immune dysregulation, closing the vicious cycle responsible for the development of endometriosis.

WIDER IMPLICATIONS

Determining the aetiology of endometriosis is a challenging issue. Posing a new hypothesis on this subject provides the initial tool necessary to design future experimental, clinical and epidemiological research that could allow for a better understanding of the origin of this disease. Furthermore, advances in the understanding of its aetiology would allow the identification of new therapeutics and preventive actions.

Exposure evaluation of diisononyl phthalate in the adults of Drosophila melanogaster: Potential risks in fertility, lifespan, behavior, and modes of action

Diisononyl phthalate (DINP) as a phthalate plasticizer is widely used in daily life and production, which shows endocrine disruption effects and has several adverse effects on the normal physiological function. Here, the effects of DINP (0.1%, 0.2%, 0.5%, and 1.0%) (v/v) on the fertility, lifespan, climbing behavior, anti-starvation ability of Drosophila melanogaster and the potential modes of action were investigated. The results showed that DINP impaired fertility in a dose-dependent manner and smaller ovarian volume, lower hatching rate, and fewer offspring was observed at higher concentrations. The effect of DINP on the lifespan showed gender-specific, and mortality was increased after exposure above 0.2% DINP. The climbing ability increased at 0.1% DINP compared with the vehicle group, while it manifested a dose-dependent decrease at higher concentrations. The anti-starvation ability exhibited hormesis after short-term culture and reduced as culture time extending. By measuring the redox status (catalase (CAT) and reactive oxygen species (ROS)) of adult flies after two exposure methods, it was found that DINP induced redox instability, which may explain the above effects at the molecular level. This study provides data to support a comprehensive analysis of DINP potential toxicity and to guide its rational use and management better.