Associations between male reproductive health and exposure to endocrine-disrupting chemicals

Maternal phthalate exposure during pregnancy and testis function of young adult sons

BACKGROUND

Phthalate exposure during fetal life may disrupt testicular development. Congruent with this, studies have found shorter anogenital distance, reduced penile size and altered hormone levels in infant boys whose mothers were exposed to higher levels of some phthalates during pregnancy. Few studies have explored if such adverse effects persist in adulthood. Thus, we aimed to explore if there is an association between fetal phthalate exposure and markers of testicular function in young adult men.

METHODS

In a longitudinal mother-child cohort from Copenhagen, Denmark, we examined 100 young men whose mothers during pregnancy had serum drawn and analyzed for 34 phthalate metabolites. Examinations of the young men took place at 18-20 years of age and included measurements of adult markers of testicular function (reproductive hormones, penile size, anogenital distance (AGD), testis volume, semen quality) and growth factors. Associations between maternal serum concentrations of phthalate metabolites and reproductive measures in the young men were tested using multiple linear regression.

RESULTS

Most consistently, higher maternal phthalate exposure was associated with higher luteinizing hormone (LH) but unchanged testosterone in adult sons. Congruently, higher maternal exposure was associated with lower total and free testosterone/LH ratios in adult sons. For example, twice as high maternal MiNP was associated with a 7.9 % (95 % CI 1.6-13.8) lower free testosterone/LH ratio. There was no consistent pattern of associations between the different phthalate metabolites and other reproductive hormones, clinical outcomes, or semen quality. None of the tested associations was significant after multiplicity adjustment.

CONCLUSIONS

In this exploratory study, higher maternal exposure to some phthalates was associated with impaired testicular Leydig cell function evidenced by a lower total and free testosterone/LH ratio in adult sons. This unique 18-20-year follow-up study raises concern and suggests that exposure of pregnant women to phthalates may have long-term effects on adult reproductive health in male offspring.

Xeno-Estrogenic Pesticides and the Risk of Related Human Cancers

In recent decades, "environmental xenobiotic-mediated endocrine disruption", especially by xeno-estrogens, has gained a lot of interest from toxicologists and environmental researchers. These estrogen-mimicking chemicals are known to cause various human disorders. Pesticides are the most heavily used harmful xenobiotic chemicals around the world. The estrogen-mimicking potential of the most widely used organochlorine pesticides is well established. However, their effect is not as clearly understood among the plethora of effects these persistent xenobiotics are known to pose on our physiological system. Estrogens are one of the principal risk modifiers of various disorders, including cancer, not only in women but in men as well. Despite the ban on these xenobiotics in some parts of the world, humans are still at apparent risk of exposure to these harmful chemicals as they are still widely persistent and likely to stay in our environment for a long time owing to their high chemical stability. The present work intends to understand how these harmful chemicals may affect the risk of the development of estrogen-mediated human cancer.

Investigation of the effect of hesperidin on some reproductive parameters in testicular toxicity induced by Bisphenol A

Bisphenol A (BPA) is one of the chemicals that cause dysfunction and infertility in testicles. Therefore, it is crucial to develop effective treatments against this damage. In this study, the effects of Hesperidin (HESP), a flavonoid in testicular toxicity induced by BPA in rats, on oxidative stress, inflammation, apoptosis, histological damage, spermatogenesis, steroidogenic enzymes and reproductive hormones were investigated. Our study used 52 Sprague Dawley male rats weighing 250-300 g, and four experimental groups were formed. From the experimental groups, 1 ml of olive oil was administered to the control group, HESP at a dose of 50 mg/kg to the HESP group, BPA at a dose of 100 mg/kg to the BPA group, HESP at a dose of 50 mg/kg to the BPA + HESP group and 100 mg/kg BPA was administered intragastrically (ig) for 14 days. We determined that BPA administration causes apoptosis, histological damage, inflammation, oxidative stress and toxic effects on spermatogenesis and steroidogenic enzymes in testicles. We observed that the administration of HESP with BPA attenuated oxidative stress, inflammation and apoptosis resulting in therapeutic effects on both steroidogenic enzymes and spermatogenesis and reproductive hormones (FSH, LH and testosterone). Our findings from this study clearly showed that while HESP treatment alleviates oxidative damage, inflammation and apoptosis in testicles of rats treated with BPA, it has regulatory effects on steroidogenic enzymes, spermatogenesis and serum reproductive hormones.

The Impact of Endocrine-Disrupting Chemicals in Male Fertility: Focus on the Action of Obesogens

The current scenario of male infertility is not yet fully elucidated; however, there is increasing evidence that it is associated with the widespread exposure to endocrine-disrupting chemicals (EDCs), and in particular to obesogens. These compounds interfere with hormones involved in the regulation of metabolism and are associated with weight gain, being also able to change the functioning of the male reproductive axis and, consequently, the testicular physiology and metabolism that are pivotal for spermatogenesis. The disruption of these tightly regulated metabolic pathways leads to adverse reproductive outcomes. The permanent exposure to obesogens has raised serious health concerns. Evidence suggests that obesogens are one of the leading causes of the marked decline of male fertility and key players in shaping the future health outcomes not only for those who are directly exposed but also for upcoming generations. In addition to the changes that lead to inefficient functioning of the male gametes, obesogens induce alterations that are “imprinted” on the genes of the male gametes, establishing a link between generations and contributing to the transmission of defects. Unveiling the molecular mechanisms by which obesogens induce toxicity that may end-up in epigenetic modifications is imperative. This review describes and discusses the suggested molecular targets and potential mechanisms for obesogenic–disrupting chemicals and the subsequent effects on male reproductive health.

Exposure to Atrazine through gestation and lactation period led to impaired sexual maturation and subfertility in F1 male rats with congenital deformities in F2 progeny

Several scientific reports suggest perturbed reproductive and developmental defects associated with environmental exposure to Atrazine (ATR). ATR has been associated with altered endocrine and reproductive functioning in-vivo exposed during the critical window of development. Thus, the present study investigates the effect of ATR exposure on F1-F2 male progeny exposed through gestation and lactation. F0 dams administered with ATR at doses 2, 10, 70, and 100 mg/kg b. wt/day from gestation day 6 to postnatal day 21. The F1 male rats were monitored for sexual maturation and subjected to fertility assessment on PND75. Delayed testicular descent was observed in 10, 70, and 100 mg/kg b. wt/day ATR dose with significantly lower serum testosterone, sperm count, and motility with testicular defects in F1 male. Expression of Androgen receptor (AR), Estrogen receptors (ER α and ER β), StAR, Aromatase, and INSL-3 were upregulated at all doses indicating estrogenic/anti-androgenic activity of ATR. Fertility assessment revealed subfertility in F1 males with high (%) pre- and post-implantation loss at 10, 70, and 100 mg/kg b. wt/day dose as compared to control. Further, F2 fetuses exhibited congenital disabilities viz. decreased weight, crown-rump length, and anogenital distance with several other morphological deformities. To conclude, ATR exerted estrogenic and/or anti-androgenic activity with fetotoxic effects through the male germline.

Evolutionary consequences of environmental effects on gamete performance

Variation in pre- and post-release gamete environments can influence evolutionary processes by altering fertilization outcomes and offspring traits. It is now widely accepted that offspring inherit epigenetic information from both their mothers and fathers. Genetic and epigenetic alterations to eggs and sperm-acquired post-release may also persist post-fertilization with consequences for offspring developmental success and later-life fitness. In externally fertilizing species, gametes are directly exposed to anthropogenically induced environmental impacts including pollution, ocean acidification and climate change. When fertilization occurs within the female reproductive tract, although gametes are at least partially protected from external environmental variation, the selective environment is likely to vary among females. In both scenarios, gamete traits and selection on gametes can be influenced by environmental conditions such as temperature and pollution as well as intrinsic factors such as male and female reproductive fluids, which may be altered by changes in male and female health and physiology. Here, we highlight some of the pathways through which changes in gamete environments can affect fertilization dynamics, gamete interactions and ultimately offspring fitness. We hope that by drawing attention to this important yet often overlooked source of variation, we will inspire future research into the evolutionary implications of anthropogenic interference of gamete environments including the use of assisted reproductive technologies. This article is part of the theme issue 'How does epigenetics influence the course of evolution?'

Uptake and translocation of multiresidue industrial and household contaminants in radish grown under controlled conditions

The uptake, bioconcentration and translocation of 22 endocrine disrupting compounds (six perflurocarboxylic acids (PFAAs), perfluorooctanoic sulfonic acid, four anionic surfactants (alkylsulfates (ASC) from C12 to C16), bisphenol A (BPA), four preservatives (parabens), two biocides (triclosan (TCS) and triclocarban (TCB)) and five UV-filters (benzophenones)) in radish (Raphanus sativus) has been investigated. Radishes were grown in sewage sludge-amended soil under controlled conditions in a grown chamber. Degradation in soil adhered to root was higher than in soil and varied significantly from a family to another. The most recalcitrant compounds were PFCs, anionic surfactants and TCB. Perfluorinated compounds and AS-C12 were detected in all plant tissues and were the compounds with the highest bioconcentration factors (BCF). A decrease of BCF was observed for ASCs with the increase of the alkyl chain. Non-ionic compounds, except TCB, were mainly accumulated in bulb. Phenolic compounds were detected at lower concentration levels than non-phenolic compounds probably due to metabolisation in radish cells. The highest BCF in edible bulb were obtained for PFOS (BCF: 1.668), perfluorooctanoic acid (BCF: 0.534) and AS-C12 (BCF: 0.523). This study reports for the first-time multiresidue plant uptake and translocation of pollutants from different chemical classes (perfluorinated compounds, surfactants, plasticiser, preservatives, biocides and UV-filters) and with a wide variety of physical-chemical properties.

Combining in vivo pathohistological and redox status analysis with in silico toxicogenomic study to explore the phthalates and bisphenol A mixture-induced testicular toxicity

The aim of this study was to: (i) determine and compare the capacity of bis (2 -ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), bisphenol A (BPA), and their mixture to produce testicular toxicity after the subacute exposure; (ii) explore the mechanisms behind the observed changes using in silico toxicogenomic approach. Male rats were randomly split into groups (n = 6): (1) Control (corn oil); (2) DEHP (50 mg/kg b.w./day); (3) DBP (50 mg/kg b.w./day); (4) BPA (25 mg/kg b.w./day); and (5) MIX (50 mg/kg b.w./day DEHP + 50 mg/kg b.w/day DBP + 25 mg/kg b.w./day BPA). Animals were sacrificed after 28 days of oral exposure, testes were extracted and prepared for histological assessments under the light microscope (haematoxylin and eosin staining) and redox status analysis. The Comparative Toxicogenomics Database (CTD; http://CTD.mdibl.org), Cytoscape software (https://cytoscape.org) and ToppGene Suite (https://toppgene.cchmc.org) were used for data-mining. Present pathohistological study has demonstrated more pronounced testicular toxicity of the MIX group (desquamated germinal epithelium cells, enlarged cells with hyperchromatic nuclei, multinucleated cell forms and intracytoplasmic vacuoles) in comparison with the single substances, while effects on redox status parameters were either more prominent, or present only in the MIX group. In silico investigation revealed 20 genes linked to male reproductive disorders, affected by all three investigated substances. Effects on metabolism, AhR pathway, apoptosis and oxidative stress could be singled out as the most probable mechanisms involved in the subacute DEHP, DBP and BPA mixture testicular toxicity, while the effect on oxidative stress parameters was confirmed by in vivo experiment.

The Association of Bisphenol A and Phthalates with Risk of Breast Cancer: A Meta-Analysis

Background: Breast cancer is the most common cancer and the second leading cause of cancer-related death amongst American women. Endocrine-disrupting chemicals (EDCs), especially bisphenol A (BPA) and phthalates, have adverse effects on human health. However, the association of BPA and phthalates with breast cancer remains conflicting. This study aims to investigate the association of BPA and phthalates with breast cancer. Methods: Correlative studies were identified by systematically searching three electronic databases, namely, PubMed, Web of Sciences, and Embase, up to November 2020. All data were analyzed using Stata 15.0. Results: A total of nine studies, consisting of 7820 breast cancer cases and controls, were included. The urinary phthalate metabolite mono-benzyl phthalate (MBzP) and mono-2-isobutyl phthalate (MiBP) were negatively associated with breast cancer (OR = 0.73, 95% CI: 0.60–0.90; OR = 0.75, 95% CI: 0.58–0.98, respectively). However, the overall ORs for BPA, mono-ethyl phthalate (MEP), mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-2-ethylhexyl phthalate (MEHP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-(3-carboxypropyl) phthalate (MCPP), and mono-butyl phthalate (MBP) were 0.85 (95% CI: 0.69–1.05), 0.96 (95% CI: 0.62–1.48), 1.12 (95% CI: 0.88–1.42), 1.13 (95% CI: 0.74–1.73), 1.01 (95% CI: 0.74–1.40), 0.74 (95% CI: 0.48–1.14), and 0.80 (95% CI: 0.55–1.15), respectively, suggesting no significant association. The sensitivity analysis indicated that the results were relatively stable. Conclusion: Phthalate metabolites MBzP and MiBP were passively associated with breast cancer, whereas no associations were found between BPA, MEP, MEHHP, MEHP, MEOHP, MCPP, and MBP and breast cancer. More high-quality case-control studies or persuasive cohort studies are urgently needed to draw the best conclusions.

Seasonal performance assessment of four riverbank filtration sites by combined non-target and effect-directed analysis

Targeting the most relevant organic micropollutants (OMP) in routine analysis appears difficult due to formation of transformation products of unknown concentration or toxicity. Performance assessment of water purification processes is still based upon limited target data. Therefore, we broadened the assessment of the removal efficiencies with combined non-target and effect-directed analysis at four riverbank filtration (RBF) sites in Germany. To assess micropollutant elimination, constancy and formation during different seasons, considering local redox conditions, travel distances and total component number in the river, non-target analysis features were grouped into categories. Furthermore, RBF sites were investigated with four endpoints (baseline toxicity, acetylcholinesterase inhibition, antibiotic effects and estrogenic effects) for thin-layer chromatography - effect-directed analysis for the first time. Results showed elimination or reduction of many features and effects, but also constancy and formation of varying proportions. Fall river samples showed precipitation-caused dilution in both tests. Spring samples showed increased effects only in acetylcholinesterase inhibition and estrogenic effects, probably due to phytoestrogens or algae bloom during vegetation period. Sites were ranked considering the total number of features, group proportions, seasonal variations and intensity and number of effects in abstraction wells. Oxic conditions and low initial component numbers in the river (Ruhr sites) resulted in less effects and fewer formations. Longer travel distances were important for a more efficient reduction of effects and features. Combination of non-target and effect-directed analysis proved to be valuable for a more comprehensive assessment of process performance beyond target analysis as also unknown OMP are observed with both methods.

Regional difference in semen quality of young men: a review on the implication of environmental and lifestyle factors during fetal life and adulthood

The prevalence of low semen quality and the incidence of testicular cancer have been steadily increasing over the past decades in different parts of the World. Although these conditions may have a genetic or epigenetic origin, there is growing evidence that multiple environmental and lifestyle factors can act alone or in combination to induce adverse effects. Exposure to these factors may occur as early as during fetal life, via the mother, and directly throughout adulthood after full spermatogenic capacity is reached. This review aims at providing an overview of past and current trends in semen quality and its relevance to fertility as well as a barometer of men’s general health. The focus will be on recent epidemiological studies of young men from the general population highlighting geographic variations in Europe. The impact of some lifestyle and environmental factors will be discussed with their role in both fetal life and adulthood. These factors include smoking, alcohol consumption, psychological stress, exposure to electromagnetic radiation, and Endocrine Disrupting Chemicals (EDCs). Finally, the challenges in investigating the influence of environmental factors on semen quality in a fast changing world are presented.

The current status and future of andrology: A consensus report from the Cairo workshop group

BACKGROUND

In attempting to formulate potential WHO guidelines for the diagnosis of male infertility, the Evidence Synthesis Group noted a paucity of high-quality data on which to base key recommendations. As a result, a number of authors suggested that key areas of research/evidence gaps should be identified, so that appropriate funding and policy actions could be undertaken to help address key questions.

OBJECTIVES

The overall objective of this Consensus workshop was to clarify current knowledge and deficits in clinical laboratory andrology, so that clear paths for future development could be navigated.

MATERIALS AND METHODS

Following a detailed literature review, each author, prior to the face-to-face meeting, prepared a summary of their topic and submitted a PowerPoint presentation. The topics covered were (a) Diagnostic testing in male fertility and infertility, (b) Male fertility/infertility in the modern world, (c) Clinical management of male infertility, and (d) The overuse of ICSI. At the meeting in Cairo on February 18, 2019, the evidence was presented and discussed and a series of consensus points agreed.

RESULTS

The paper presents a background and summary of the evidence relating to these four topics and addresses key points of significance. Following discussion of the evidence, a total of 36 consensus points were agreed.

DISCUSSION

The Discussion section presents areas where there was further debate and key areas that were highlighted during the day.

CONCLUSION

The consensus points provide clear statements of evidence gaps and/or potential future research areas/topics. Appropriate funding streams addressing these can be prioritized and consequently, in the short and medium term, answers provided. By using this strategic approach, andrology can make the rapid progress necessary to address key scientific, clinical, and societal challenges that face our discipline now and in the near future.

In vitro and in vivo endocrine disrupting effects of the azole fungicides triticonazole and flusilazole

Azoles are effective antifungal agents used in both medicine and agriculture. They typically work by inhibiting cytochrome P450 enzymes, primarily CYP51 of the ergosterol biosynthesis pathway, thus damaging the fungal cell membrane. However, apart from their desired antifungal properties, several azoles also exhibit endocrine disrupting properties in mammals, both in vitro and in vivo. Here, we have tested two currently used agricultural azole fungicides, triticonazole and flusilazole, for their in vitro anti-androgenic activity and potential effects on reproductive parameters. Both fungicides showed strong androgen receptor (AR) antagonism and disruption of steroid biosynthesis in vitro. Following gestational exposure to flusilazole (15 or 45 mg/kg bw/day) or triticonazole (150 or 450 mg/kg bw/day) in time-mated Sprague Dawley rats, triticonazole induced shorter male anogenital distance (AGD). Flusilazole exposure did not affect the AGD, but altered fetal male blood hormone profile, with increased androstenedione and decreased estrone levels. Flusilazole and triticonazole have dissimilar effects on reproductive parameters in vivo, but both show endocrine disrupting activities.