Endocrine disruptors and testicular function

Impact of heat waves on semen quality: A retrospective study in Argentina between 2005 and 2023

Heat waves, defined as periods with daily temperatures surpassing the historical average for a specific region, have become more frequent worldwide in recent years. Previous studies have reported a negative association between temperature and semen quality, but the focus has mainly been on Asian and European populations. The study included 54,926 men (18-60 years) undergoing routine semen analysis between 2005 and 2023 at CEUSA-LAEH andrology unit, in Buenos Aires, Argentina. Hourly temperature readings were provided by the Servicio Meteorológico Nacional. R programming (R Studio v2022.07.2) was used to define heat waves, calculate key characteristics, visualize results, and perform statistical tests at the IBYME laboratory. During the period studied, a total of 124 days had heat waves (defined after at least 3 consecutive days with 32.3 °C and 22 °C). Men exposed to heat waves during spermatogenesis exhibited lower sperm number (concentration and count; P < 0.0001) and decreased normal morphology (percentage of normal sperm and normal motile count; P < 0.05) compared to those not exposed. These differences were most pronounced between semen samples from years with several heat waves (2013, 2023) and none (2005, 2007, 2016), displaying 4-5 times higher fold changes (P < 0.05). Further analysis employing multiple regression revealed a significantly negative association between semen quality and heat wave length, suggesting that a prolonged exposure may be more detrimental than an acute exposure. Subsequent analysis focusing on prolonged exposure (≥6-days heat wave) during spermatogenesis revealed a negative (P < 0.05) association between early exposure (spermatocytogenesis: 64-90 days prior semen collection) and semen quality. This study underscores the negative association between early exposure to heat waves during sperm development and semen quality, raising concerns about its possible association with the worldwide declining male fertility. A comprehensive collaborative approach is crucial, involving global governmental policies, sustainable practices, and coordinated efforts across scientific, healthcare, and policy domains.

A System Biology Approach Reveals New Targets for Human Thyroid Gland Toxicity in Embryos and Adult Individuals

Compounds of natural or synthetic origin present in personal care products, food additives, and packaging may interfere with hormonal regulation and are called endocrine-disrupting chemicals (EDCs). The thyroid gland is an important target of these compounds. The objective of this study was to analyze public data on the human thyroid transcriptome and investigate potential new targets of EDCs in the embryonic and adult thyroid glands. We compared the public transcriptome data of adult and embryonic human thyroid glands and selected 100 up- or downregulated genes that were subsequently subjected to functional enrichment analysis. In the embryonic thyroid, the most highly expressed gene was PRMT6, which methylates arginine-4 of histone H2A (86.21%), and the downregulated clusters included plasma lipoprotein particles (39.24%) and endopeptidase inhibitory activity (24.05%). For the adult thyroid gland, the most highly expressed genes were related to the following categories: metallothionein-binding metals (56.67%), steroid hormone biosynthetic process (16.67%), and cellular response to vascular endothelial growth factor stimulus (6.67%). Several compounds ranging from antihypertensive drugs to enzyme inhibitors were identified as potentially harmful to thyroid gland development and adult function.

Genistein prevents the production of hypospadias induced by Di-(2-ethylhexyl) phthalate through androgen signaling and antioxidant response in rats

Environmental estrogen exposure has increased dramatically over the past 50 years. In particular, prenatal exposure to estrogen causes many congenital diseases, among which reproductive system development disorders are extremely serious. In this study, the molecular mechanism of hypospadias and the therapeutic effect of genistein (GEN) were investigated through in vivo models prepared by Di-(2-ethylhexyl) phthalate (DEHP) exposure between 12 and 19 days of gestation. With increased DEHP concentrations, the incidence of hypospadias increased gradually. DEHP inhibited the key enzymes involved in steroid synthesis, resulting in decreasing testosterone synthesis. At the same time, DEHP increased reactive oxygen species (ROS) and produced inflammatory factors via NADPH oxidase-1 (NOX1) and NADPH oxidase-4 (NOX4) pathways. It also inhibited Steroid 5 α Reductase 2 (Srd5α2) and decreased dihydrotestosterone (DHT) synthesis. Additionally, DEHP inhibited the androgen receptor (AR), resulting in reduced DHT binding to the AR that ultimately retarded the development of the external reproductive system. GEN, a phytoestrogen, competes with DEHP for binding to estrogen receptor β (ERβ). This competition, along with GEN's antiestrogen and antioxidant properties, could potentially reverse impairments. The findings of this study provide valuable insights into the role of phytoestrogens in alleviating environmental estrogen-induced congenital diseases.

Disruption of gonocyte development following neonatal exposure to di (2-ethylhexyl) phthalate

Pre- and/or post-natal administrations of di(2-ethylhexyl) phthalate (DEHP) in experimental animals cause alterations in the spermatogenesis. However, the mechanism by which DEHP affects fertility is unknown and could be through alterations in the survival and differentiation of the gonocytes. The aim of the present study was to evaluate the effect of a single administration of DEHP in newborn mice on gonocytic proliferation, differentiation and survival and its long-term effects on seminiferous epithelium and sperm quality. BALB/c mice distributed into Control and DEHP groups were used. Each animal in the DEHP group was given a single dose of 500 mg/Kg at birth. The animals were analyzed at 1, 2, 4, 6, 8, 10 and 70 days postpartum (dpp). Testicular tissues were processed for morphological analysis to determine the different types of gonocytes, differentiation index, seminiferous epithelial alterations, and immunoreactivity to Stra8, Pcna and Vimentin proteins. Long-term evaluation of the seminiferous epithelium and sperm quality were carried out at 70 dpp. The DEHP animal group presented gonocytic degeneration with delayed differentiation, causing a reduction in the population of spermatogonia (Stra8 +) in the cellular proliferation (Pcna+) and disorganization of Vimentin filaments. These events had long-term repercussions on the quality of the seminiferous epithelium and semen. Our study demonstrates that at birth, there is a period that the testes are extremely sensitive to DEHP exposure, which leads to gonocytic degeneration and delay in their differentiation. This situation can have long-term repercussions or permanent effects on the quality of the seminiferous epithelium and sperm parameters.

Postnatal Exposure to the Endocrine Disruptor Dichlorodiphenyltrichloroethane Affects Adrenomedullary Chromaffin Cell Physiology and Alters the Balance of Mechanisms Underlying Cell Renewal

Dichlorodiphenyltrichloroethane (DDT) is a wide-spread systemic pollutant with endocrine disrupting properties. Prenatal exposure to low doses of DDT has been shown to affect adrenal medulla growth and function. The role of postnatal exposure to DDT in developmental disorders remains unclear. The aim of the present investigation is to assess growth parameters and the expression of factors mediating the function and renewal of chromaffin cells in the adult adrenal medulla of male Wistar rats exposed to the endocrine disruptor o,p'-DDT since birth until sexual maturation. The DDT-exposed rats exhibited normal growth of the adrenal medulla but significantly decreased tyrosine hydroxylase production by chromaffin cells during postnatal period. Unlike the control, the exposed rats showed enhanced proliferation and reduced expression of nuclear β-catenin, transcription factor Oct4, and ligand of Sonic hedgehog after termination of the adrenal growth period. No expression of pluripotency marker Sox2 and absence of Ascl 1-positive progenitors were found in the adrenal medulla during postnatal ontogeny of the exposed and the control rats. The present findings indicate that an increase in proliferative activity and inhibition of the formation of reserve for chromaffin cell renewal, two main mechanisms for cell maintenance in adrenal medulla, in the adult DDT-exposed rats may reflect a compensatory reaction aimed at the restoration of catecholamine production levels. The increased proliferation of chromaffin cells in adults suggests excessive growth of the adrenal medulla. Thus, postnatal exposure to DDT alters cell physiology and increases the risk of functional insufficiency and hyperplasia of the adrenal medulla.

The adverse role of endocrine disrupting chemicals in the reproductive system

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

Insulin desensitization and cell senescence induced by heat stress in pig testicular cell model

Thermostatic animals need to maintain a stable body temperature. A high-temperature environment can cause body temperature to exceed the range of tolerance of the organism, resulting in a heat stress response. The reproductive organs (such as the testes) are more sensitive to temperature due to their special anatomical location. However, to date, the effect of heat stress on the biological function of insulin in testicular cells has not been revealed. Therefore, the current study established a testis cell model to study the effect of heat stress on the biological activity of insulin. The results showed significant alterations in the insulin-induced intracellular signaling under heat stress conditions. Moreover, the IR-mediated intracellular signaling pathway was significantly downregulated under heat stress conditions. Further studies demonstrated that heat stress led to senescence of testicular cells by Sa-β-gal staining. Furthermore, the expression of senescence markers (p16 and p21) was increased under heat stress. In addition, heat stress was found to cause oxidative stress in testicular cells, which may be the underlying molecular mechanism by which heat stress changes the signaling properties of insulin. Collectively, the current study showed that heat stress caused alterations in insulin-induced intracellular signaling. Heat stress also induced testicular cell senescence.

Risk and mortality of testicular cancer in patients with neurodevelopmental or other psychiatric disorders

BACKGROUND

Both testicular germ cell tumours (TGCT) and neurodevelopmental disorders are associated with urogenital malformations. Few studies have investigated the association between psychiatric disorders and TGCT. We investigated whether history of any psychiatric or neurodevelopmental disorder is associated with increased risk or mortality of TGCT.

METHOD

This is a nested case-control study including 6166 TGCT patients diagnosed during 1992-2014, individually matched for age and calendar period to 61,660 controls. We calculated odds ratios (ORs) for the association between type of psychiatric diagnoses and TGCT risk. Among the cases, we used a cohort design and calculated hazard ratios (HRs) of the association between psychiatric diagnose and all-cause and TGCT-specific death.

RESULTS

History of a neurodevelopmental disorder (attention deficit hyperactivity disorder, autism spectrum disorder and intellectual disabilities) was associated with an increased risk of seminoma (OR: 1.54; 1.09-2.19). Seminoma patients with neurodevelopmental disorders were younger (34 versus 38 years, p = 0.004) and had more stage IV disease (5.4% versus 1.2%) than those without. Psychiatric history overall was not associated with TGCT. Patient history of any psychiatric disorder was associated with an increased all-cause and TGCT-specific death.

CONCLUSIONS

We report an association between neurodevelopmental disorders and testicular seminoma, and an increased TGCT-specific mortality for TGCT patients with psychiatric disorders.

Developmental Exposure to DDT Disrupts Transcriptional Regulation of Postnatal Growth and Cell Renewal of Adrenal Medulla

Dichlorodiphenyltrichloroethane (DDT) is the most widespread persistent pollutant with endocrine-disrupting properties. DDT has been shown to disrupt secretory and morphogenetic processes in the adrenal cortex. The present investigation aimed to evaluate transcriptional regulation of postnatal growth of the adrenal medulla and formation of the pools necessary for self-renewal of medullary cells in rats that developed under low-dose exposure to DDT. The study was performed using male Wistar rats exposed to low doses of o,p'-DDT during prenatal and postnatal development. Light microscopy and histomorphometry revealed diminished medulla growth in the DDT-exposed rats. Evaluation of Ki-67 expression in chromaffin cells found later activation of proliferation indicative of retarded growth of the adrenal medulla. All DDT-exposed rats exhibited a gradual decrease in tyrosine hydroxylase production by adrenal chromaffin cells. Immunohistochemical evaluation of nuclear β-catenin, transcription factor Oct4, and ligand of sonic hedgehog revealed increased expression of all factors after termination of growth in the control rats. The DDT-exposed rats demonstrated diminished increases in Oct4 and sonic hedgehog expression and lower levels of canonical Wnt signaling activation. Thus, developmental exposure to the endocrine disruptor o,p'-DDT alters the transcriptional regulation of morphogenetic processes in the adrenal medulla and evokes a slowdown in its growth and in the formation of a reserve pool of cells capable of dedifferentiation and proliferation that maintain cellular homeostasis in adult adrenals.

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.

Impact of Fetal Exposure to Endocrine Disrupting Chemical Mixtures on FOXA3 Gene and Protein Expression in Adult Rat Testes

Perinatal exposure to endocrine disrupting chemicals (EDCs) has been shown to affect male reproductive functions. However, the effects on male reproduction of exposure to EDC mixtures at doses relevant to humans have not been fully characterized. In previous studies, we found that in utero exposure to mixtures of the plasticizer di(2-ethylhexyl) phthalate (DEHP) and the soy-based phytoestrogen genistein (Gen) induced abnormal testis development in rats. In the present study, we investigated the molecular basis of these effects in adult testes from the offspring of pregnant SD rats gavaged with corn oil or Gen + DEHP mixtures at 0.1 or 10 mg/kg/day. Testicular transcriptomes were determined by microarray and RNA-seq analyses. A protein analysis was performed on paraffin and frozen testis sections, mainly by immunofluorescence. The transcription factor forkhead box protein 3 (FOXA3), a key regulator of Leydig cell function, was identified as the most significantly downregulated gene in testes from rats exposed in utero to Gen + DEHP mixtures. FOXA3 protein levels were decreased in testicular interstitium at a dose previously found to reduce testosterone levels, suggesting a primary effect of fetal exposure to Gen + DEHP on adult Leydig cells, rather than on spermatids and Sertoli cells, also expressing FOXA3. Thus, FOXA3 downregulation in adult testes following fetal exposure to Gen + DEHP may contribute to adverse male reproductive outcomes.

Environmental disruptors and testicular cancer

PURPOSE

Testicular cancer (TC) is the most common malignancy among young adult males. The etiology is multifactorial, and both environmental and genetic factors play an essential role in the origin and development of this tumor. In particular, exposure to environmental endocrine disruptors (EEDs), resulting from industrialization and urbanization, seems crucial both in pre-and postnatal life. However, the lack of long-term studies on a wide caseload and the difficulty in evaluating their toxic effects in vivo make it challenging to establish a causal link. This review aims to discuss the main human epidemiological studies currently available in the literature to define a possible association between these chemicals and TC.

METHODS

A comprehensive Medline/PubMed and Embase search was performed, selecting all relevant, peer-reviewed papers in English published from 2002 to January 2022. Other relevant papers were selected from the reference lists.

RESULTS

To date, literature evidence is limited due to the scarcity and heterogeneity of human studies and shows controversial data, highlighting the complexity of the topic. However, most human epidemiological studies seem to point toward a correlation between EEDs exposure and TC.

CONCLUSION

Although the molecular mechanisms are not yet fully understood, the role of EEDs in TC onset is plausible, but several factors, such as the individual genetic background, the exposure time, and the complex mechanism of action of these chemicals, do not allow defining the causal link with certainty and make further studies necessary to investigate this complex topic.

The murine male reproductive organ at a glance: Three-dimensional insights and virtual histology using label-free light sheet microcopy

BACKGROUND

The unique anatomy of the male reproductive organ reflects its complex function from sperm maturation to their storage for months until emission. Since light microscopy in two dimensions (2d) cannot sufficiently demonstrate its complex morphology, a comprehensive visualization is required to identify pathologic alterations in its entire anatomical context.

OBJECTIVES

Aim of this study was to use three-dimensional (3d) light sheet fluorescence microscopy (LSFM) to visualize entire murine testes in 3d, label-free and at subcellular resolution, and to assign local autofluorescence to testicular and deferent structures.

MATERIALS AND METHODS

Murine testes were fixed with four different fixatives and subsequently cleared with benzoic acid/benzyl benzoate. Hereafter, complete murine testes were scanned with LSFM with different fluorescence filter sets and subsequently embedded in paraffin for further conventional planar histology.

RESULTS

Autofluorescence signals of the murine reproductive organ allowed the unambiguous identification of the testicular anatomy from the seminiferous tubules to the vas deferens with their specific stratification independent of the used fixative. Blood vessels were visualized from the pampiniform plexus to the small capillaries of single tubules. Moreover, due to the specific intrinsic fluorescence properties of the efferent ducts and the epididymis, luminal caliber, the epithelial stratification and retronuclear cytoplasmic inclusions gave a unique insight into the interface of both morphological structures. Subsequent 2d histology confirmed the identified morphological structures.

DISCUSSION

LSFM analysis of the murine reproductive organ allows due to its intrinsic fluorescence a simple, label-free 3d assessment of its entire duct morphology, the epithelial composition and the associated blood supply in its anatomical relation.

CONCLUSION

LSFM provides the technical basis for comprehensive analyses of pathologically altered murine testes in its entirety by depicting specific autofluorescence. Thereby it facilitates mouse studies of testicular disease or their drug related alterations in more detail potentially for clinical translation assessing human testicular biopsies. This article is protected by copyright. All rights reserved.

Global qualitative and quantitative distribution of micropollutants in the deep sea

Micropollutants (MPs) include a wide range of biological disruptors that can be toxic to wildlife and humans at very low concentrations (<1 μg/L). These mainly anthropogenic pollutants have been widely detected in different areas of the planet, including the deep sea, and have impacts on marine life. Because of this potential toxicity, the global distribution, quantity, incidence, and potential impacts of deep-sea MPs were investigated in a systematic review of the literature. The results showed that MPs have reached different zones of the ocean and are more frequently reported in the Northern Hemisphere, where higher concentrations are found. MPs are also concentrated in depths up to 3000 m, where they are also more frequently studied, but also extend deeper than 10,000 m. Potentially toxic metals (PTMs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDTs), organotins, and polycyclic aromatic hydrocarbons (PAHs) were identified as the most prevalent and widely distributed MPs at ≥200 m depth. PTMs are widely distributed in the deep sea in high concentrations; aluminum is the most prevalent up to 3000 m depth, followed by zinc and copper. PCBs, organotins, hexachlorocyclohexanes (HCHs), PAHs, and phenols were detected accumulated in both organisms and environmental samples above legislated thresholds or known toxicity levels. Our assessment indicated that the deep sea can be considered a sink for MPs.

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.

Mediterranean Diet as a Shield against Male Infertility and Cancer Risk Induced by Environmental Pollutants: A Focus on Flavonoids

The role of environmental factors in influencing health status is well documented. Heavy metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, dioxins, pesticides, ultrafine particles, produced by human activities put a strain on the body’s entire defense system. Therefore, together with public health measures, evidence-based individual resilience measures are necessary to mitigate cancer risk under environmental stress and to prevent reproductive dysfunction and non-communicable diseases; this is especially relevant for workers occupationally exposed to pollutants and/or populations residing in highly polluted areas. The Mediterranean diet is characterized by a high intake of fruits and vegetables rich in flavonoids, that can promote the elimination of pollutants in tissues and fluids and/or mitigate their effects through different mechanisms. In this review, we collected evidence from pre-clinical and clinical studies showing that the impairment of male fertility and gonadal development, as well as cancers of reproductive system, due to the exposure of organic and inorganic pollutants, may be counteracted by flavonoids.

In vitro impact of genistein and mono(2-ethylhexyl) phthalate (MEHP) on the eicosanoid pathway in spermatogonial stem cells

Perinatal exposures to endocrine disrupting chemicals (EDCs) alter the male reproductive system. Infants are exposed to genistein (GEN) through soy-based formula, and to Mono(2-ethylhexyl) Phthalate (MEHP), metabolite of the plasticizer DEHP. Spermatogonial stem cells (SSCs) are formed in infancy and their integrity is essential for spermatogenesis. Thus, understanding the impact of EDCs on SSCs is critical. Prostaglandins (PGs) are inflammatory mediators synthesized via the eicosanoid pathway starting with cyclooxygenases (Coxs), that regulate physiological and pathological processes. Our goal was to study the eicosanoid pathway in SSCs and examine whether it was disrupted by GEN and MEHP, potentially contributing to their adverse effects. The mouse C18-4 cell line used as SSC model expressed high levels of Cox1 and Cox2 genes and proteins, and eicosanoid pathway genes similarly to levels measured in primary rat spermatogonia. Treatments with GEN and MEHP at 10 and 100 μM decreased Cox1 gene and protein expression, whereas Cox2, phospholipase A2, prostaglandin synthases transcripts, PGE2, PGF2a and PGD2 were upregulated. Simultaneously, the transcript levels of spermatogonia progenitor markers Foxo1 and Mcam and differentiated spermatogonial markers cKit and Stra8 were increased. Foxo1 was also increased by EDCs in primary rat spermatogonia. This study shows that the eicosanoid pathway is altered during SSC differentiation and that exposure to GEN and MEHP disrupts this process, mainly driven by GEN effects on Cox2 pathway, while MEHP acts through an alternative mechanism. Thus, understanding the role of Cox enzymes in SSCs and how GEN and MEHP exposures alter their differentiation warrants further studies.

Chemical pollution: A growing peril and potential catastrophic risk to humanity

Anthropogenic chemical pollution has the potential to pose one of the largest environmental threats to humanity, but global understanding of the issue remains fragmented. This article presents a comprehensive perspective of the threat of chemical pollution to humanity, emphasising male fertility, cognitive health and food security. There are serious gaps in our understanding of the scale of the threat and the risks posed by the dispersal, mixture and recombination of chemicals in the wider environment. Although some pollution control measures exist they are often not being adopted at the rate needed to avoid chronic and acute effects on human health now and in coming decades. There is an urgent need for enhanced global awareness and scientific scrutiny of the overall scale of risk posed by chemical usage, dispersal and disposal.

Immunohistochemical insights into a hidden pathology: Canine cryptorchidism

Cryptorchidism is a common disorder in the canine population with some aspects still unclear. Although the bilateral condition is known to lead to fertility problems and predisposition to testicular cancer, the neoplastic risk for scrotal testis in unilateral cryptorchid dog is controversial. Therefore, the therapeutic approach to the canine unilateral cryptorchid is arbitrary so far. This study aimed to investigate precancerous testicular lesions, such as immaturity and atrophy, and compare them in scrotal and undescended testes using an in-depth diagnostic analysis based on immunophenotypic patterns. With this purpose, 26 adult male dogs of different ages and breeds, affected by unilateral or bilateral cryptorchidism were enrolled. After surgical removal, testes were examined immunohistochemically to assess their positivity for specific markers of the canine foetal/neonatal period, that is vimentin (VIM), cytokeratin (CK), desmin (DES), inhibin-α (INH), and anti-Müllerian hormone (AMH) in Sertoli cells, and placental alkaline phosphatase (PLAP) in germ cells. Except for the ubiquitous VIM, all the markers were more expressed in neoplastic gonads compared to healthy ones (P < 0.05). Similarly, testes detected with Sertoli cell-only tubules as well as with Sertoli cells hyperplasia showed higher expression than gonads without such alterations for CK, DES, AMH and PLAP, and for CK and DES, respectively (P < 0.05). The same trend was observed in undescended respect to scrotal testes even though their positivity was significant only for DES, INH and AMH (P < 0.05). Immunohistochemical positivity found in scrotal testes of unilateral cryptorchid dogs, even in absence of detectable anatomical abnormalities, was suggestive of precancerous lesions. Despite the limited sample size, this study could help to clarify the predisposition to neoplastic development in normally descended testes. These markers expression in adult life could allow identifying the early stages of the testicular carcinogenesis process besides suggesting a precautionary bilateral surgical approach in unilateral cryptorchid dogs.

The Beneficial Role of Natural Endocrine Disruptors: Phytoestrogens in Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia with a growing incidence rate primarily among the elderly. It is a neurodegenerative, progressive disorder leading to significant cognitive loss. Despite numerous pieces of research, no cure for halting the disease has been discovered yet. Phytoestrogens are nonestradiol compounds classified as one of the endocrine-disrupting chemicals (EDCs), meaning that they can potentially disrupt hormonal balance and result in developmental and reproductive abnormalities. Importantly, phytoestrogens are structurally, chemically, and functionally akin to estrogens, which undoubtedly has the potential to be detrimental to the organism. What is intriguing, although classified as EDCs, phytoestrogens seem to have a beneficial influence on Alzheimer's disease symptoms and neuropathologies. They have been observed to act as antioxidants, improve visual-spatial memory, lower amyloid-beta production, and increase the growth, survival, and plasticity of brain cells. This review article is aimed at contributing to the collective understanding of the role of phytoestrogens in the prevention and treatment of Alzheimer's disease. Importantly, it underlines the fact that despite being EDCs, phytoestrogens and their use can be beneficial in the prevention of Alzheimer's disease.

Endocrine disruptors and the male reproductive system

In recent years, there has been an increased incidence in several of the most common reproductive disorders, including hypospadias and cryptorchidism in newborns, and testicular cancer and lower sperm quality in young adult males. In addition, the timing of puberty has also changed over time. Although the cause of these reproductive effects is a matter of intense debate, a link with the presence of ubiquitous compounds in the environment, or the exposure to specific groups of medications during foetal life, has been suggested. Results from epidemiological and experimental studies, as well as clinical observations in humans indicate that endocrine-disrupting chemicals may be associated with those disorders. In this review, we will summarize the results of epidemiological studies and experimental studies utilising human testicular cells or tissue. Due to increasing public interest and the recently published data, the main focus will be on the effects of prenatal exposure to mild analgesics.

Air Pollution and COVID-19: A Possible Dangerous Synergy for Male Fertility

Several studies indicate that semen quality has strongly declined in the last decades worldwide. Air pollution represents a significant co-factor with the COVID-19 impact and has negative effects on the male reproductive system, through pro-oxidant, inflammatory and immune-dysregulating mechanisms. It has recently been reported that chronic exposure to PM2.5 causes overexpression of the alveolar ACE2 receptor, the entry route of SARS-CoV-2 into the organism shared by the lungs and testis where expression is highest in the body. In the testis, the ACE2/Ang-(1-7)/MasR pathway plays an important role in the regulation of spermatogenesis and an indirect mechanism of testicular damage could be due to the blockade of the ACE2 receptor by SARS-CoV-2. This prevents the conversion of specific angiotensins, and their excess causes inflammation with the overproduction of cytokines. PM2.5-induced overexpression of the alveolar ACE2 receptor, in turn, could increase local viral load in patients exposed to pollutants, producing ACE2 receptor depletion and compromising host defenses. By presenting an overall view of epidemiological data and molecular mechanisms, this manuscript aims to interpret the possible synergistic effects of both air pollution and COVID-19 on male reproductive function, warning that the spread of SARS-CoV-2 in the fertile years may represent a significant threat to global reproductive health. All of this should be of great concern, especially for men of the age of maximum reproductive capacity, and an important topic of debate for policy makers. Altered environmental conditions, together with the direct and indirect short- and long-term effects of viral infection could cause a worsening of semen quality with important consequences for male fertility, especially in those areas with higher environmental impact.

EDCs and male urogenital cancers

Male sex determination and sexual differentiation occur between 6-12 weeks of gestation. During the "male programming window" the fetal testes start to produce testosterone that initiates the development of the male reproductive tract. Exposure to endocrine disrupting chemicals (EDCs) able to mimic or disrupt steroid hormone actions may disrupt testicular development and adversely impact reproductive health at birth, during puberty and adulthood. The testicular dysgenesis syndrome (TDS) occurs as a result inhibition of androgen action on fetal development preceding Sertoli and Leydig cell dysfunction and may result from direct or epigenetic effects. Hypospadias, cryptorchidism and poor semen quality are elements of TDS, which may be considered a risk factor for testicular germ cell cancer (TGCC). Exposure to estrogen or estrogenic EDCs results in developmental estrogenization/estrogen imprinting in the rodent for prostate cancer (PCa). This can disrupt prostate histology by disorganization of the epithelium, prostatic intraepithelial neoplasia (PIN) lesions, in particular high-grade PIN (HGPIN) lesions which are precursors of prostatic adenocarcinoma. These defects persist throughout the lifespan of the animal and later in life estrogen exposure predispose development of cancer. Exposure of pregnant dams to vinclozolin, a competitive anti-androgen, and results in prominent, focal regions of inflammation in all exposed animals. The inflammation closely resembles human nonbacterial prostatitis that occurs in young men and evidence indicates that inflammation plays a central role in the development of PCa. In conclusion, in utero exposure to endocrine disrupters may predispose to the development of TDS, testicular cancer (TCa) and PCa and are illustrations of Developmental Origins of Health and Disease (DOHaD).

Isoflavones alter male and female fertility in different development windows

Isoflavones are a group of secondary metabolites found in plants belonging to the class of phytoestrogens. These, because they have a chemical structure similar to the endogenous hormone 17β-estradiol, act as endocrine disruptors over the different development window periods. This study aimed to evaluate male and female reproductive systems' responses when exposed to isoflavones during the development window. It is characterized as a bibliographic review, built after analyzing clinical and preclinical articles indexed in English, Portuguese, and Spanish published in the last ten years. The isoflavones, aglycone or glucosides, have essential therapeutic properties in the relief of postmenopausal symptoms in women, reduce the proliferation of cancers, in addition to being antioxidants. On the other hand, they can still behave in a similar way to 17β-estradiol, binding to hormone receptors and acting as endocrine disruptors over the gestational period until pre-puberty, negatively affecting the development of the reproductive system. The effects on reproduction are not dose-response but are influenced by the type of isoflavone and period. There are variations in the serum concentration of hormones and action on their negative feedback on the hypothalamic-pituitary-testicular axis in males. Reproductive functions are also affected by spermatogenesis, such as decreased sperm count, lower reproductive performance, reduced litter size, low sperm production, and reduced seminal vesicle size. In females, puberty is reached later, irregular estrous cycle, reduced weight of the ovary, uterus, lower serum levels of estradiol and progesterone, reduced fertility, or interrupted fertility. At the end of the analysis of the selected publications, it can be concluded that despite the beneficial therapeutic effects in the face of pathologies, the unknown consumption of doses and types of isoflavones in food can damage the development and reproduction of individuals. Therefore, further studies must be carried out to elucidate the usual safe doses of the analyzed phytoestrogen. Greater control over insertion in foods targeted at pediatric consumers should be implemented until we have adequate safety.

Effects of the prenatal environment on cryptorchidism: A narrative review

Cryptorchidism, the absence of testes from the scrotum, is the most common genital disorder in boys and a risk factor for reduced fertility and testicular cancer. The mechanism responsible for cryptorchidism involves two discrete stages: a transabdominal and an inguinoscrotal phase. These phases of testicular descent are regulated by the prenatal sex hormone environment, including levels of testosterone, insulin-like factor 3, and calcitonin gene-related peptide. Environmental endocrine disruptors, which are unfavorable environmental factors, may also affect testicular descent through prenatal sex hormones. This review examined the effects of environmental factors, particularly environmental endocrine disruptors, such as phthalates, organochlorine pesticides, diethylstilbestrol, bisphenol A, dioxins/dioxin-like compounds, and perfluoroalkyl substances, and parental lifestyles on the risk of cryptorchidism. Although some studies have shown that environmental endocrine disruptors can affect testicular descent by changing the hormonal environment during the prenatal period, no significant association has been established between exposure to environmental endocrine disruptors and the incidence of cryptorchidism. Therefore, the role played by environmental endocrine disruptor exposure (if any) in the pathogenesis of cryptorchidism remains unknown. Further studies are needed to examine these issues.

Estrogens and development of the rete testis, efferent ductules, epididymis and vas deferens

Estrogen has always been considered the female hormone and testosterone the male hormone. However, estrogen's presence in the testis and deleterious effects of estrogen treatment during development have been known for nearly 90 years, long before estrogen receptors (ESRs) were discovered. Eventually it was learned that testes actually synthesize high levels of estradiol (E2) and sequester high concentrations in the reproductive tract lumen, which seems contradictory to the overwhelming number of studies showing reproductive pathology following exogenous estrogen exposures. For too long, the developmental pathology of estrogen has dominated our thinking, even resulting in the "estrogen hypothesis" as related to the testicular dysgenesis syndrome. However, these early studies and the development of an Esr1 knockout mouse led to a deluge of research into estrogen's potential role in and disruption of development and function of the male reproductive system. What is new is that estrogen action in the male cannot be divorced from that of androgen. This paper presents what is known about components of the estrogen pathway, including its synthesis and target receptors, and the need to achieve a balance between androgen- and estrogen-action in male reproductive tract differentiation and adult functions. The review focuses on what is known regarding development of the male reproductive tract, from the rete testis to the vas deferens, and examines the expression of estrogen receptors and presence of aromatase in the male reproductive system, traces the evidence provided by estrogen-associated knockout and transgenic animal models and discusses the effects of fetal and postnatal exposures to estrogens. Hopefully, there will be enough here to stimulate discussions and new investigations of the androgen:estrogen balance that seems to be essential for development of the male reproductive tract.

[Cancers of the external genital organs of male in Hérault: Results from the Hérault tumor register (RTH) over a period of 30 years (1987-2016)]

AIM

The objective of this study is to present the history of cancers of the external genital organs of male in Hérault using data from the Hérault tumor register (RTH) over a period of 30 years.

PATIENTS AND METHODS

Using the RTH database, we studied the development of testicular germ cell tumors (TGCT) and penile cancer (PC) over 30 years, from 1987 to 2016. We analyzed the incidence and mortality data for these tumors. We compared these results to French, European and global data.

RESULTS

In 30 years of registration we have recorded 725 cases of TGCT and 175 cases of PC. The age standardized incidence rate (ASR) of TGCT has doubled between 1987 and 2016 (4.2 per 100,000 in 1987 and 9.3 per 100,000 in 2016). It was multiplied by 2.63 in the population of patients aged 30 to 44. There is a decrease of the mortality rate with a ASR of 0.8 deaths per 100,000 in 1987, and 0.4/100 000 in 2016. The PC incidence ASR was stable between 1987 and 2016 (0.4-0.9/100,000). Mortality is stable with a ASR between 0.1 and 0.3 deaths per 100,000 between 1987 and 2016.

CONCLUSION

The incidence of TGCT has increased sharply in the Hérault over the past 30 years, while a decrease in mortality has been observed. The proportion of seminomas is increasing; it has gone from 53 % to 60 % in 30 years in the Hérault. The incidence and mortality of PC shows a stability in the Hérault over the past 30 years.

Bisphenol A Deranges the Endocannabinoid System of Primary Sertoli Cells with an Impact on Inhibin B Production

Bisphenol A (BPA) is an endocrine disruptor that negatively affects spermatogenesis, a process where Sertoli cells play a central role. Thus, in the present study we sought to ascertain whether BPA could modulate the endocannabinoid (eCB) system in exposed mouse primary Sertoli cells. Under our experimental conditions, BPA turned out to be cytotoxic to Sertoli cells with an half-maximal inhibitory concentration (IC₅₀) of ~6.0 µM. Exposure to a non-cytotoxic dose of BPA (i.e., 0.5 μM for 48 h) increased the expression levels of specific components of the eCB system, namely: type-1 cannabinoid (CB₁) receptor and diacylglycerol lipase-α (DAGL-α), at mRNA level, type-2 cannabinoid (CB₂) receptor, transient receptor potential vanilloid 1 (TRPV1) receptors, and DAGL-β, at protein level. Interestingly, BPA also increased the production of inhibin B, but not that of transferrin, and blockade of either CB₂ receptor or TRPV1 receptor further enhanced the BPA effect. Altogether, our study provides unprecedented evidence that BPA deranges the eCB system of Sertoli cells towards CB₂- and TRPV1-dependent signal transduction, both receptors being engaged in modulating BPA effects on inhibin B production. These findings add CB₂ and TRPV1 receptors, and hence the eCB signaling, to the other molecular targets of BPA already known in mammalian cells.

Neonatal maternal separation causes decreased numbers of sertoli cell, spermatogenic cells, and sperm in mice

Neonatal maternal separation is an experimental model used to evaluate the effects of toxic stress in neonates, or early life stress. Although various physiological and psychological stresses during childhood have been reported, the effects of neonatal maternal separation on the male reproductive system remain unclear. Therefore, the present study evaluated the effects of neonatal maternal separation on the male reproductive system. In neonatal male ICR mice, maternal separation was performed for 0.5, 1, 2, and 4 hours/day, from postnatal day 1 to 10. At 10 weeks of age, the neonatal maternal separation mice exhibited decreases in both testicular weight and epididymal sperm number, along with various testicular morphological changes involving germ cells, Sertoli cells, and interstitial cells. Notably, neonatal maternal separation mice showed decreased numbers of Sertoli cells. Animals subjected to 0.5-, 1-, and 2-h/day neonatal maternal separation exhibited decreases in serum levels of testosterone but not in those of gonadotropin (luteinizing hormone and follicle-stimulating hormone). Together, these data showed that neonatal maternal separation in male mice causes decreased Sertoli cell numbers following puberty, resulting in subsequent decreased spermatogenic activity.

Exogenous Oestrogen Impacts Cell Fate Decision in the Developing Gonads: A Potential Cause of Declining Human Reproductive Health

The increasing incidence of testicular dysgenesis syndrome-related conditions and overall decline in human fertility has been linked to the prevalence of oestrogenic endocrine disrupting chemicals (EDCs) in the environment. Ectopic activation of oestrogen signalling by EDCs in the gonad can impact testis and ovary function and development. Oestrogen is the critical driver of ovarian differentiation in non-mammalian vertebrates, and in its absence a testis will form. In contrast, oestrogen is not required for mammalian ovarian differentiation, but it is essential for its maintenance, illustrating it is necessary for reinforcing ovarian fate. Interestingly, exposure of the bi-potential gonad to exogenous oestrogen can cause XY sex reversal in marsupials and this is mediated by the cytoplasmic retention of the testis-determining factor SOX9 (sex-determining region Y box transcription factor 9). Oestrogen can similarly suppress SOX9 and activate ovarian genes in both humans and mice, demonstrating it plays an essential role in all mammals in mediating gonad somatic cell fate. Here, we review the molecular control of gonad differentiation and explore the mechanisms through which exogenous oestrogen can influence somatic cell fate to disrupt gonad development and function. Understanding these mechanisms is essential for defining the effects of oestrogenic EDCs on the developing gonads and ultimately their impacts on human reproductive health.

One day is better than four days of ejaculatory abstinence for sperm function

According to the World Health Organization guidelines, ejaculatory abstinence (EA) of 2–7 days is recommended for semen analysis. This study aimed to determine how seminal quality may be affected by two EA periods from the same man. Seminal samples from 65 men were evaluated by conventional semen analysis and qualitative characteristics after 1 and 4 days of EA (two samples/man). The semen was qualitatively analyzed by examining oxidative activity (intracellular and seminal plasma), sperm function (acrosome integrity, mitochondrial activity, and nuclear DNA integrity), and epididymal function. As expected, samples collected after 1 day of EA showed a decrease in volume and sperm total number compared to samples collected after 4 days of EA. The sperm motility of the samples collected after 1 day of EA was better compared to samples collected after 4 days of EA. Oxidative activity measured was lower after 1 day of EA compared with those measured after 4 days of EA. With regards to sperm function, samples collected after 1 day of EA showed an increase in acrosome integrity, mitochondrial activity, and nuclear DNA integrity compared with samples collected after 4 days of EA. Epididymal function showed no difference between the two-time points. Although samples collected after 4 days of EA showed better results for sperm quantity, samples collected after 1 day of EA showed better qualitative results, including motility, oxidative activity, and sperm function. Thus, it can be concluded that sperm storage at the epididymal tail may make spermatozoa more susceptible to oxidative damage.

Effects and Mechanisms of Phthalates' Action on Reproductive Processes and Reproductive Health: A Literature Review

The production of plastic products, which requires phthalate plasticizers, has resulted in the problems for human health, especially that of reproductive health. Phthalate exposure can induce reproductive disorders at various regulatory levels. The aim of this review was to compile the evidence concerning the association between phthalates and reproductive diseases, phthalates-induced reproductive disorders, and their possible endocrine and intracellular mechanisms. Phthalates may induce alterations in puberty, the development of testicular dysgenesis syndrome, cancer, and fertility disorders in both males and females. At the hormonal level, phthalates can modify the release of hypothalamic, pituitary, and peripheral hormones. At the intracellular level, phthalates can interfere with nuclear receptors, membrane receptors, intracellular signaling pathways, and modulate gene expression associated with reproduction. To understand and to treat the adverse effects of phthalates on human health, it is essential to expand the current knowledge concerning their mechanism of action in the organism.

Transcriptomic analysis identifies early cellular and molecular events by which estrogen disrupts testis differentiation and causes feminization in Xenopus laevis

Extensive studies have shown that estrogenic endocrine-disrupting chemicals (EDCs) can disrupt testis differentiation and even cause feminization in vertebrates. However, little is known about the mechanisms by which estrogenic EDCs disrupt testis differentiation. Here, we employed Xenopus laevis, a model amphibian species sensitive to estrogenic EDCs, to explore the molecular and cellular events by which 17β-estradiol (E2) disrupts testis differentiation and causes feminization. Following waterborne exposure to E2 from stage 45/46, genetically male X. laevis were confirmed to undergo testis differentiation inhibition and ovary differentiation activation at stages 52 and 53, ultimately displaying gonadal feminization at stage 66. Using a time-course RNA sequencing approach, we then identified thousands of differentially expressed transcripts (DETs) in genetically male gonad-mesonephros complexes at stages 48, 50 and 52 (the window for testis differentiation) between E2 treatment and the control. Enrichment analysis suggests alterations in cell proliferation, extracellular matrix, and cell motility following E2 exposure. Further verification by multiple methods demonstrated that E2 inhibited cell proliferation, disrupted extracellular matrix, and altered cell motility in the genetically male gonads compared with controls, implying that these events together contributed to testis differentiation disruptions and feminization in X. laevis. This study for the first time uncovered some of the early molecular and cellular events by which estrogen disrupts testicular differentiation and causes feminization in X. laevis. These new findings improve our understanding of the mechanisms by which estrogenic EDCs disrupt testicular differentiation in vertebrates.

Association of endocrine active environmental compounds with body mass index and weight loss following bariatric surgery

INTRODUCTION

The objective of this study was to study associations of a wide range of halogenated biphenyls, dibenzo-p-dioxins, dibenzofurans and diphenylethers with body mass index (BMI) and evaluate changes in their concentration following bariatric surgery.

METHODS

Subcutaneous fat, visceral fat and liver tissue samples were collected from 106 patients undergoing Roux-en-Y gastric bypass surgery for weight loss or patients who were undergoing abdominal surgery for nonbariatric reasons. We measured concentrations of an extensive panel of chlorinated and brominated biphenyls, dioxins, and furans, and brominated diphenylethers in the samples. We conducted linear regression to examine associations with BMI, adjusting for age and gender. Changes in concentration for indicator chemicals were evaluated in samples collected following bariatric surgery in a small subpopulation.

RESULTS

After adjustments for age and gender and correction for multiple testing, seven ortho-chlorinated biphenyls, one nonortho-chlorinated biphenyl, four PCDD/Fs and one ortho-brominated biphenyl were associated with BMI. The strongest associations between BMI and lipid-adjusted concentrations were seen with PCB-105 in subcutaneous fat (beta = 16.838 P-val = 1.45E-06) PCB-126 in visceral fat (beta = 15.067 P-val = 7.72E-06) and PCB-118 (beta = 14.101 P-val = 2.66E-05) in liver. The concentrations of sum PCBs, chlorinated toxic equivalent quantity (TEQ's) and brominated compounds increased significantly with weight loss in subcutaneous fat in a group of ten individuals resampled up to five years after bariatric surgery and substantial weight loss.

CONCLUSION

We show that selected polychlorinated biphenyls PCBs and structurally related polychlorinated dibenzo-p-dioxins dibenzofurans (PCDD/Fs) were associated with BMI. Concentrations of these lipophilic compounds in subcutaneous fat increased following bariatric surgery.

Exposure to polychlorinated compounds and cryptorchidism; A nested case-control study

Background

Maldescended testes or cryptorchidism is a genital birth defect that affects 2–9% of all male new-borns. Over the last 40 years there have been reports of increased prevalence in countries like the US, the UK and the Scandinavian countries. This possible increase has in some studies been linked to a foetal exposure to chemical pollutants. In this matched case-control study, we analysed maternal serum samples in early pregnancy for three different organochlorine compounds, to investigate whether the levels were associated with the risk of cryptorchidism.

Method

Maternal serum samples taken during the first trimester of pregnancy from 165 cases (boys born with cryptorchidism) and 165 controls, matched for birth year and maternal age, parity and smoking habits during the pregnancy, were retrieved from the Southern Sweden Maternity Biobank. The samples were analysed for 2,2’,4,4’,5,5’-hexachlorobiphenyl (PCB-153), dichlorodiphenyltrichloroethane (p,p’-DDE) and hexachlorobenzene (HCB), using gas chromatography mass spectrometry. Associations between exposure and cryptorchidism were evaluated by conditional logistic regression.

Results

We found no statistically significantly associations between exposure to these compounds and cryptorchidism, either when the exposure variables were used as a continuous variable, or when the exposure levels were divided in quartiles.

Conclusion

We found no evidence of an association between maternal levels of PCB-153, p,p’-DDE or HCB during the pregnancy and the risk of having cryptorchidism in the sons.

Biomonitoring of occupational exposure to phthalates: A systematic review

INTRODUCTION

Phthalates, a group of ubiquitous industrial chemicals, have been widely used in occupational settings, mainly as plasticizers in a variety of applications. Occupational exposure to different phthalates has been studied in several occupational settings using human biomonitoring (HBM).

AIM

To provide a comprehensive review of the available literature on occupational exposure to phthalates assessed using HBM and to determine future data needs on the topic as part of the HBM4EU project.

METHODS

A systematic search was carried out in the databases of Pubmed, Scopus, and Web of Science for articles published between 2000 and September 4, 2019 using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A total of 22 studies on the occupational HBM of phthalates was considered suitable for review.

RESULTS AND DISCUSSION

Among the reviewed studies, 19 (86%) focused on DEHP, an old phthalate that is now subject to authorization and planned to be restricted in the EU. Concentrations of MEHHP, one of its metabolites, varied up to 13-fold between studies and across sectors when comparing extreme geometric means, ranging from 11.6 (similar to the general populations) to 151 μg/g creatinine. Only 2 studies focused on newer phthalates such as DiNP and DPHP. Concerning the geographical distribution, 10 studies were performed in Europe (including 6 in Slovakia), 8 in Asia, and 4 in North America, but this distribution is not a good reflection of phthalate production and usage levels worldwide. Most HBM studies were performed in the context of PVC product manufacturing. Future studies should focus on: i) a more uniform approach to sampling timing to facilitate comparisons between studies; ii) newer phthalates; and iii) old phthalates in waste management or recycling.

CONCLUSION

Our findings highlight the lack of recent occupational HBM studies on both old and new phthalate exposure in European countries and the need for a harmonized approach. Considering the important policy actions taken in Europe regarding phthalates, it seems relevant to evaluate the impact of these actions on exposure levels and health risks for workers.

Prenatal perfluoroalkyl substances and newborn anogenital distance in a Canadian cohort

Exposure to the man-made chemicals perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS) and perfluorohexanesulfonate (PFHxS) is widespread. These perfluoroalkyl substances (PFASs) have been associated with androgenic endocrine-disrupting properties; however, the evidence is equivocal and few human studies have examined the association between prenatal exposure to PFASs and markers of androgenic endocrine disruption such as changes in anogenital distance (AGD). In the MIREC cohort, PFOA, PFOS and PFHxS were analyzed in first trimester maternal plasma. AGD was measured in 205 male and 196 female newborns. The change in estimate procedure was used to identify confounders by sex and AGD in multiple linear regression models. Geometric mean plasma concentrations (95% CI) for PFOA, PFOS and PFHxS were 1.71 (1.61, 1.81), 4.40 (4.18, 4.64) and 1.15 (1.06, 1.25) μg/L, respectively. A one-unit increase in natural log transformed PFOA was associated with a 1.36 mm (95% CI 0.30, 2.41) increase in anoscrotal distance, adjusting for household income, active smoking status during pregnancy and gestational age. However, when examined by quartiles, a non-monotonic pattern was observed with wide confidence intervals. No consistent patterns were observed between maternal PFAS concentrations and female AGDs. This study found no clear evidence that maternal plasma concentrations of PFOS, PFOA or PFHxS were associated with shorter infant anogenital distance in males or any change in AGD in females. Whether the positive association observed between longer anoscrotal distance and PFOA is real or would have any long-lasting effect on the reproductive health of males is unknown and needs to be investigated further.

Prepubertal acrylamide exposure causes dose-response decreases in spermatic production and functionality with modulation of genes involved in the spermatogenesis in rats

The increase in human infertility prevalence due to male reproductive disorders has been associated with extensive endocrine-disrupting chemical (EDC) exposure. Acrylamide (AA) is a compound formed spontaneously during heat processing of some foods that are mainly consumed by children and adolescents. In this study, we evaluated the prepubertal AA exposure effects on male adult reproductive physiology using a prepubertal experimental model to analyze the pubertal development, spermatogenesis hormones levels and genes expression involved in male reproductive function. This study is the first one to use the validated protocol to correlate the AA exposure with puberty development, as well as the AA-induced endocrine disrupting effects on reproductive axis. AA did not affect the age at puberty, the reproductive organ's weight and serum hormonal levels. AA reduces spermatogenesis, induces morphological and functional defects on sperm and alters transcript expression of sexual hormone receptors (Ar and Esr2), the transcript expression of Tnf, Egr2, Rhcg and Lrrc34. These findings suggest that excessive AA consumption may impair their reproductive capacity at adulthood, despite no changes in hormonal profile being observed.

Endocrine disrupting chemicals: exposure, effects on human health, mechanism of action, models for testing and strategies for prevention

Endocrine Disrupting Chemicals (EDCs) are a global problem for environmental and human health. They are defined as "an exogenous chemical, or mixture of chemicals, that can interfere with any aspect of hormone action". It is estimated that there are about 1000 chemicals with endocrine-acting properties. EDCs comprise pesticides, fungicides, industrial chemicals, plasticizers, nonylphenols, metals, pharmaceutical agents and phytoestrogens. Human exposure to EDCs mainly occurs by ingestion and to some extent by inhalation and dermal uptake. Most EDCs are lipophilic and bioaccumulate in the adipose tissue, thus they have a very long half-life in the body. It is difficult to assess the full impact of human exposure to EDCs because adverse effects develop latently and manifest at later ages, and in some people do not present. Timing of exposure is of importance. Developing fetus and neonates are the most vulnerable to endocrine disruption. EDCs may interfere with synthesis, action and metabolism of sex steroid hormones that in turn cause developmental and fertility problems, infertility and hormone-sensitive cancers in women and men. Some EDCs exert obesogenic effects that result in disturbance in energy homeostasis. Interference with hypothalamo-pituitary-thyroid and adrenal axes has also been reported. In this review, potential EDCs, their effects and mechanisms of action, epidemiological studies to analyze their effects on human health, bio-detection and chemical identification methods, difficulties in extrapolating experimental findings and studying endocrine disruptors in humans and recommendations for endocrinologists, individuals and policy makers will be discussed in view of the relevant literature.

GPER and Testicular Germ Cell Cancer

The G protein-coupled estrogen receptor (GPER), also known as GPR30, is a widely conserved 7-transmembrane-domain protein which has been identified as a novel 17β-estradiol-binding protein that is structurally distinct from the classic oestrogen receptors (ERα and ERβ). There are still conflicting data regarding the exact role and the natural ligand of GPER/GPR30 in reproductive tracts as both male and female knock-out mice are fertile and have no abnormalities of reproductive organs. Testicular germ cell cancers (TGCCs) are the most common malignancy in young males and the most frequent cause of death from solid tumors in this age group. Clinical and experimental studies suggested that estrogens participate in the physiological and pathological control of male germ cell proliferation. In human seminoma cell line, while 17β-estradiol (E2) inhibits in vitro cell proliferation through an ERβ-dependent mechanism, an impermeable E2 conjugate (E2 coupled to BSA), in vitro cell proliferation is stimulated by activating ERK1/2 and protein kinase A through a membrane GPCR that we further identified as GPER/GPR30. The same effect was observed with low but environmentally relevant doses of BPA, an estrogenic endocrine disrupting compound. Furthermore, GPER/GPR30 is specifically overexpressed in seminomas but not in non-seminomas and this overexpression is correlated with an ERβ-downregulation. This GPER/GPR30 overexpression could be linked to some genetic variations, as single nucleotide polymorphisms, which was also reported in other hormone-dependent cancers. We will review here the implication of GPER/GPR30 in TGCCs pathophysiology and the arguments to consider GPER/GPR30 as a potential therapeutic target in humans.

Impact of binary waterborne mixtures of nickel and zinc on hypothalamic-pituitary-testicular axis in rats

Several evidences from the literature showed that the coexistence of nickel and zinc in polluted waters is related to the similarity in their geogenic and anthropogenic factors. Although most environmental exposures to metals do not occur singly, there is a paucity of scientific knowledge on the effects of zinc and nickel co-exposure on mammalian reproductive health. The present study investigated the influence of co-exposure to nickel and zinc on male reproductive function in rats. Experimental rats were co-exposed to environmentally relevant concentrations of waterborne nickel (75 and 150 μg NiCl₂ L^-1) and zinc (100 and 200 μg ZnCl₂ L^-1) for 45 successive days. Subsequently, reproductive hormones were assayed whereas the hypothalamus, epididymis and testes of the rats were processed for the assessment of oxidative stress and inflammation indices, caspase-3 activity and histology. Results indicated that co-exposure to nickel and zinc significantly (p < 0.05) abolished nickel-mediated diminution of antioxidant defense mechanisms while diminishing levels of reactive oxygen and nitrogen species and lipid peroxidation in the hypothalamus, epididymis and testes of the exposed rats. Additionally, co-exposure to zinc abated nickel-mediated diminutions in luteinizing hormone, follicle-stimulating hormone, serum and intra-testicular testosterone with concomitant enhancement of sperm production and quality. Further, zinc abrogated nickel-mediated elevation in inflammatory biomarkers including nitric oxide, tumor necrosis factor alpha, interleukin-1 beta as well as caspase-3 activity. The protective influence of zinc on nicked-induced reproductive toxicity was well supported by histological data. Overall, zinc ameliorated nickel-induced reproductive dysfunction via its anti-oxidant, anti-inflammatory, anti-apoptotic and spermato-protective activities in rats.

Is Testicular Germ Cell Cancer Estrogen Dependent? The Role of Endocrine Disrupting Chemicals

Testicular germ cell cancer (TGCC) is the most frequent cancer of the young male, with an increasing incidence worldwide. The pathogenesis and reasons for this increase remain unknown. However, epidemiological and experimental data have suggested that, similar to genital malformations and sperm impairment, it could result from the interaction of genetic and environmental factors including fetal exposure to endocrine-disrupting chemicals (EDCs) with estrogenic effects. In this review, we analyze the expression of classic and nonclassic estrogen receptors by TGCC cells, the way they may influence germ cell proliferation induced by EDCs, and discuss how this estrogen dependency supports the developmental and environmental hypothesis.

Acute exposure to perfluorononanoic acid in prepubertal mice: Effect on germ cell dynamics and an insight into the possible mechanisms of its inhibitory action on testicular functions

Perfluoroalkyl acids (PFAAs) are anthropogenic compounds used globally in a variety of commercial products. Perfluorononanoic acid (PFNA), a member of PFAAs, is detected in human blood and this has been reported to cause hepatotoxic, immunotoxic, and developmental and testicular toxic effects in laboratory animals. We have recently shown that the acute exposure to PFNA in prepubertal Parkes (P) mice impairs spermatogenesis by inducing oxidative stress and inhibiting testosterone biosynthesis in the testis. The present study was aimed to examine the effect of acute exposure to PFNA in prepubertal P mice on germ cell dynamics and to understand the possible mechanisms of action of this compound on testicular functions. PFNA (2 and 5 mg/kg body weight) was orally administered to male mice for 14 days from postnatal day 25-38. The treatment caused a decrease in overall germ cell transformation. The results also reveal that impairment in testicular functions in treated mice is associated with alterations in cholesterol and glucose homeostasis; further, an inhibition in expressions of growth hormone receptor (GHR), insulin-like growth factor-1 (IGF-1), insulin-like growth factor-1 receptor (IGF-1R), androgen receptor (AR), phosphorylated mammalian target of rapamycin (p-mTOR) and peroxisome proliferator activated receptor α (PPAR α) in the testis is also implicated in this action. The findings thus suggest involvement of multiple factors which altogether contribute to the alterations in spermatogenic process and testosterone production following acute exposure to PFNA in prepubertal mice.

Glycan Analysis as Biomarkers for Testicular Cancer

The U.S. Preventive Services Task Force does not recommend routine screening for testicular cancer (TC) in asymptomatic men, essentially because serological testicular cancer (TC) biomarkers are not reliable. The main reason is that two of the most important TC biomarkers, α-fetoprotein (AFP) and human chorionic gonadotropin (hCG), are not produced solely due to TC. Moreover, up to 40% of patients with TC do not have elevated serological biomarkers, which is why serial imaging with CT is the chief means of monitoring progress. On the other hand, exposure to radiation can lead to an increased risk of secondary malignancies. This review provides the first comprehensive account of the applicability of protein glycoprofiling as a promising biomarker for TC with applications in disease diagnostics, monitoring and recurrence evaluation. The review first deals with the description and classification of TC. Secondly, the limitations of current TC biomarkers such as hCG, AFP and lactate dehydrogenase are provided together with an extensive overview of the glycosylation of hCG and AFP related to TC. The final part of the review summarises the potential of glycan changes on either hCG and AFP as TC biomarkers for diagnostics and prognostics purposes, and for disease recurrence evaluation. Finally, an analysis of glycans in serum and tissues as TC biomarkers is also provided.

Isolation and molecular characterization of spermatogonia from male Sprague-Dawley rats exposed in utero and postnatally to dibutyl phthalate or acrylamide

The increased incidence of testicular disorders in young men and the possible influence of environmental chemicals, such as dibutyl phthalate (DBP) and acrylamide (AA), requires experimental models for identifying modes of action. Most published reproductive toxicologic studies use RNA samples from the total testis to evaluate testicular gene expression; however, analyses of isolated cell types could provide a more specific tool. Among testicular germ cells, spermatogonia are critical since they represent the onset of spermatogenesis. This study aimed, (1) to establish a technique for spermatogonia isolation; (2) to apply this isolation technique to verify possible gene expression alterations (Pou5f1, Kitlg, Mki-67, Bak1 and Spry4) in prepubertal post-natal day, (PND24) and pubertal (PND45) testes after in utero and postnatal exposure to DBP or AA. The technique was efficient for isolation of a majority of spermatogonia. In utero DBP exposure led to reduced litter body weight at birth, reduced anogenital distance of male pups on PND4, and increased frequency of male nipple retention on PND14 compared to controls. DBP-exposed relative testes weights were reduced only at PND24 compared to control but they did not differ at PND45. DBP-exposed animals showed reduced expression levels of Pou5f1 and Mki67 on PND24, and reduced expression of Pou5f1 and Spry4 on PND45. AA exposure reduced expression of Pou5f1, Mki67, and Spry4 at PND45 although not significantly. Our results suggest that DBP acts by reducing cell proliferation and impairing differentiation in prepubertal and pubertal testes.

Hormonal Imprinting: The First Cellular-level Evidence of Epigenetic Inheritance and its Present State

Hormonal imprinting takes place perinatally at the first encounter between the developing hormone receptor and its target hormone. This process is needed for the normal function of the receptor-hormone pair and its effect is life-long. However, in this critical period, when the developmental window is open, related molecules (members of the same hormone family, synthetic hormones and hormone-like molecules, endocrine disruptors) also can be bound by the receptor, causing life-long faulty imprinting. In this case, the receptors’ binding capacity changes and alterations are caused at adult age in the sexual and behavioral sphere, in the brain and bones, inclination to diseases and manifestation of diseases, etc. Hereby, faulty hormonal imprinting is the basis of metabolic and immunological imprinting as well as the developmental origin of health and disease (DOHaD). Although the perinatal period is the most critical for faulty imprinting, there are other critical periods as weaning and adolescence, when the original imprinting can be modified or new imprintings develop. Hormonal imprinting is an epigenetic process, without changing the base sequence of DNA, it is inherited in the cell line of the imprinted cells and also transgenerationally (up to 1000 generations in unicellulars and up to the 3_rd generation in mammals are justified). Considering the enormously growing number and amount of faulty imprinters (endocrine disruptors) and the hereditary character of faulty imprinting, this latter is threatening the whole human endocrine system.