Urinary bisphenol A levels in young men: association with reproductive hormones and semen quality

Bisphenol A and its potential mechanism of action for reproductive toxicity

Bisphenol A (BPA) is an organic synthetic chemical used worldwide. Billions of pounds of BPA are produced annually through industrial processes to be used in commercial products, making human exposure to BPA ubiquitous. Concerns have been raised due to the potential adverse health effects of BPA, specifically in vulnerable populations, such as pregnant persons and children. BPA is an endocrine-disrupting chemical, and through this function has been linked to reproductive toxicity. We review BPA's historical and current use, health and safety concerns and regulations, sources of exposure, and evidence for male and female reproductive toxicity. Evidence from epidemiological and animal studies idenfity that low- and high-exposure levels of BPA (prenatal, postnatal and adulthood exposure) can adversely affect male and female fertility and reproductive organs. While the cause of BPA-induced reproductive toxicity is not fully understood, we discuss BPA's estrogenic and androgenic activity, and its ability to disrupt the hypothalamic-pituitary-gonadal axis as a potential associated mechanism. There are significant differences in tolerable daily intakes of BPA set by global agencies, making interpretation of previous and emerging research findings challenging and inconsistent. Although BPA is deemed toxic by some government agencies, most do not currently consider it a health risk due to low populational exposure levels. However, we highlight evidence that even at acute, low exposure, BPA can adversely affect reproductive function. We recommend continuing research into the adverse effects of BPA on human health and revisiting the regulatory measures of BPA to limit exposure and promote public awareness of its potential to cause reproductive toxicity.

Environmentally-relevant doses of bisphenol A and S exposure in utero disrupt germ cell programming across generations resolved by single nucleus multi-omics

Background

Exposure to endocrine-disrupting chemicals (EDCs), such as bisphenol A (BPA), disrupts reproduction across generations. Germ cell epigenetic alterations are proposed to bridge transgenerational reproductive defects resulting from EDCs. Previously, we have shown that prenatal exposure to environmentally relevant doses of BPA or its substitute, BPS, caused transgenerationally maintained reproductive impairments associated with neonatal spermatogonial epigenetic changes in male mice. While epigenetic alterations in germ cells can lead to transgenerational phenotypic variations, the mechanisms sustaining these changes across generations remain unclear.

Objectives

This study aimed to systematically elucidate the mechanism of transgenerational inherence by prenatal BPA and BPS exposure in the murine germline from F1 to F3 generations at both transcriptomic and epigenetic levels.

Methods

BPA or BPS with doses of 0 (vehicle control), 0.5, 50, or 1000 μg/kg/b.w./day was orally administered to pregnant CD-1 females (F0) from gestational day 7 to birth. Sperm counts and motility were examined in F1, F2, and F3 adult males. THY1+ germ cells on postnatal day 6 from F1, F2, and F3 males at a dose of 50 μg/kg/b.w./day were used for analysis by single-nucleus (sn) multi-omics (paired snRNA-seq and snATAC-seq on the same nucleus).

Results

Prenatal exposure to BPA and BPS with 0.5, 50, and 1000 μg/kg/b.w./day reduced sperm counts in mice across F1 to F3 generations. In the F1 neonatal germ cells, ancestral BPA or BPS exposure with 50 μg/kg/b.w./day resulted in increased differentially expressed genes (DEGs) associated with spermatogonial differentiation. It also disrupted the balance between maintaining the undifferentiated and differentiating spermatogonial populations. Differentially accessible peaks (DAPs) by snATAC-seq were primarily located in the promoter regions, with elevated activity of key transcription factors, including SP1, SP4, and DMRT1. Throughout F1-F3 generations, biological processes related to mitosis/meiosis and metabolic pathways were substantially up-regulated in BPA- or BPS-exposed groups. While the quantities of DEGs and DAPs were similar in F1 and F2 spermatogonia, with both showing a significant reduction in F3. Notably, approximately 80% of DAPs in F1 and F2 spermatogonia overlapped with histone post-translational modifications linked to transcription activation, such as H3K4me1/2/3 and H3K27ac. Although BPA exerted more potent effects on gene expression in F1 spermatogonia, BPS induced longer-lasting effects on spermatogonial differentiation across F1 to F3 males. Interestingly, DMRT1 motif activity was persistently elevated across all three generations following ancestral BPA or BPS exposure.

Discussion

Our work provides the first systematic analyses for understanding the transgenerational dynamics of gene expression and chromatin landscape following prenatal exposure to BPA or BPS in neonatal spermatogonia. These results suggest that prenatal exposure to environmentally relevant doses of BPA or BPS alters chromatin accessibility and transcription factor motif activities, consequently contributing to disrupted transcriptional levels in neonatal germ cells, and some are sustained to F3 generations, ultimately leading to the reduction of sperm counts in adults.

The impact of Bisphenol-A on human reproductive health

Bisphenol-A (BPA) is a recognized endocrine-disrupting chemical used to produce several consumer goods and products. There has been widespread exposure to BPA because of increased industrial production and use of BPA-containing products. As a result of these exposures, BPA is found in several human body fluids and can cause endocrine disruption by interfering with hormone signaling pathways and epigenetic modifications. Therefore, human reproductive health and development have been adversely affected by BPA. This review aimed to consolidate existing knowledge on the impact of BPA on human reproductive health, examining its effects on both males and females. To achieve this, we systematically searched four databases for studies that associated BPA with reproductive health (male and female), after which we retrieved the important information from the selected articles. There was an association of reproductive health diseases with high BPA exposure. In males, BPA was associated with increased sperm alterations, altered reproductive hormone levels, and testicular atrophy. In females, there was an association of BPA exposure with hormonal imbalances, reduced ovarian reserve, and increased likelihood of conditions such as fibroids, polycystic ovarian syndrome, endometriosis and infertility. BPA's pervasive presence and its harmful effects on reproductive health underscore the need for global regulation and public awareness. Although substantial evidence from animal and in vitro studies supports the detrimental effects of BPA, there is a need for more human-focused research, particularly in developing countries, to confirm these findings. This review advocates for increased regulatory measures to limit BPA exposure.

High seminal BPA in IVF patients correlates with lower sperm count and up-regulated miR-21 and miR-130a

Bisphenol A (BPA) is a widespread industrial chemical, used as the key monomer of polycarbonate plastics and epoxy resins. BPA has been detected in human seminal fluid and has been correlated with changes in sperm parameters, crucial in determining male fertility. In this study, semen samples were collected from 100 patients aged 29-47 years undergoing fertility assessment between 2021 and 2023 and analyzed according to WHO guidelines. BPA levels in the seminal plasma were then measured through an enzyme-linked immunosorbent assay (ELISA) and compared to sperm quality metrics. The relative mRNA/miRNA expression of key genes associated to male reproduction, including androgen receptor, miR-34c, miR-21, miR-130a, was then quantified and compared between groups with high or low BPA content. Our results revealed that BPA levels were increased with age and were negatively correlated with sperm counts (p<0.05). The negative correlation remained significant when patients were age-matched. No other relationships between seminal BPA and motility, morphology or DNA fragmentation levels were observed. qPCR analysis showed that androgen receptor mRNA expression was significantly greater in sperm with high seminal BPA (p<0.05). Moreover, we found that the expression of miR-21 and miR-130a was also upregulated in the higher BPA group (p<0.05). These results display a relationship between BPA content in the semen and male fertility parameters, and provide insights into the molecular mechanisms through which BPA may be affecting male reproductive capability. Ultimately, this research can potentially drive changes to guidelines and exposure limits for BPA exposure.

The relationship between semen quality in male infertility clinic patients and bisphenol A：A Chinese cross-sectional study

Bisphenol A (BPA) is a growing concern as an endocrine-disrupting chemical due to its adverse health effects. However, the association between BPA and sperm quality in adult human males remains unclear. The aim of this study was to assess the daily life exposure level of BPA and analyze its correlation with sperm quality in males. Patients who sought treatment in Chinese infertility clinics between May and October 2023 were selected as study subjects. We determined participants' serum BPA content using high-performance liquid chromatography. Sperm count and motility were assessed using a computer-aided sperm analysis system, while sperm morphology was analyzed using an improved Papanicolaou stain. A total of 405 participants, averaging 33.01 ± 5.44 years old, were included. We observed low semen quality among participants in infertility clinics. Principal component analysis was performed for each semen quality index, and three principal components reflecting sperm motility, count, and morphology were extracted. The participants' mean serum BPA level was 6.96 ng/mL. Negative correlations were observed between serum BPA content and total sperm count, sperm density, forward motility rate, and non-forward motility rate. A positive correlation was found between the non-motile sperm rate and the head deformity rate. Morphological abnormalities were the predominant adverse effects observed. Despite low daily life BPA exposure, long-term low-dose exposure in the general population may damage semen quality. This study provides a scientific basis for managing health risks associated with BPA exposure.

Maternal bisphenols exposure and thyroid function in children: a systematic review and meta-analysis

Background

Evidence from animal experiments and epidemiological studies has reported controversial results about the effects of prenatal bisphenols (BPs) exposure on childhood thyroid function. This study aims to explore the associations of prenatal exposure to BPs with thyroid-related hormones (THs) in newborns and early childhood, with a particular focus on the sex-dependent and exposure level effects.

Methods

Correlated studies were systematically searched from PubMed, Web of Science, Medline, Cochrane, and Embase until February 21, 2024. The exposures assessed include bisphenol A (BPA), bisphenol F (BPF), bisphenol S (BPS), bisphenol AF (BPAF), and tetrachlorobisphenol A (TCBPA). THs measured were thyroid stimulating hormone (TSH), total tri-iodothyronine (TT3), total thyroxine (TT4), free tri-iothyronine (FT3), and free thyroxine (FT4). Effect estimates were quantified using coefficients from multivariable regression models. Statistical analyses were completed using Stata 16.0. The methodological quality of the included studies was evaluated using the Newcastle-Ottawa Scale (NOS).

Results

Eleven cohort studies comprising 5,363 children were included in our meta-analysis. Prenatal bisphenol concentrations were statistically significant related to alterations in thyroid hormones in children, exclusively in female offspring, including reduced TSH (β = -0.020, 95% CI: -0.036, -0.005) and increased TT3 levels (β = 0.011, 95% CI: 0.001, 0.021), and exposure to high concentration of bisphenols (>1.5 ug/g creatinine) significantly reduced FT3 levels in children (β = -0.011, 95% CI: -0.020, -0.003).

Conclusion

Prenatal bisphenol exposure is linked to alterations in thyroid hormone levels in girls, necessitating enhanced measures to control bisphenol exposure levels during pregnancy for child health protection.

Systematic Review Registration

https://inplasy.com, identifier INPLASY202450129.

Health risks of Bisphenol-A exposure: From Wnt signaling perspective

Human beings are routinely exposed to chronic and low dose of Bisphenols (BPs) due to their widely pervasiveness in the environment. BPs hold similar chemical structures to 17β-estradiol (E2) and thyroid hormone, thus posing threats to human health by rendering the endocrine system dysfunctional. Among BPs, Bisphenol-A (BPA) is the best-known and extensively studied endocrine disrupting compound (EDC). BPA possesses multisystem toxicity, including reproductive toxicity, neurotoxicity, hepatoxicity and nephrotoxicity. Particularly, the central nervous system (CNS), especially the developing one, is vulnerable to BPA exposure. This review describes our current knowledge of BPA toxicity and the related molecular mechanisms, with an emphasis on the role of Wnt signaling in the related processes. We also discuss the role of oxidative stress, endocrine signaling and epigenetics in the regulation of Wnt signaling by BPA exposure. In summary, dysfunction of Wnt signaling plays a key role in BPA toxicity and thus can be a potential target to alleviate EDCs induced damage to organisms.

The Association of ICSI Outcomes with Semen and Blood Bisphenol A Concentrations of the Male Partner

This study investigated the association of blood and semen Bisphenol A (BPA) levels of the male partner on the reproductive outcome in intracytoplasmic sperm injection (ICSI) treatment cycles. For this prospective study (ClinicalTrials.gov identifier: NCT02703584), blood and semen samples of the male partner of the 75 women who had ICSI were analyzed. The study group consisted of men who had ICSI for male factor infertility other than azoospermia, while men with normal spermiogram whose partners underwent ICSI due to tubal factor infertility were taken as the study group. Habitual consumption of drinking water from plastic carboys/bottles (PBW) at home was also questioned in both groups as it was considered as chronic BPA exposure. The association of ICSI outcome with blood BPA (bBPA) and semen BPA (sBPA) levels was analyzed in both groups. No significant correlation was found between sperm parameters and bBPA levels in both groups. A negative correlation was found between sBPA levels and total sperm count and progressive sperm motility in men who consumed PBW. Embryo development arrest was found to be significantly higher in patients who have high sBPA levels. Although sBPA levels were not different in PBW consumers, bBPA levels were found to be significantly lower in those who consumed tap water (TW) than those who used PBW. Elevated bBPA were associated with a significant decrease in clinical pregnancy rate. Considering the widespread human exposure to BPA, the effect of BPA on the male reproductive system needs to be further examined.

Bisphenol A Exposure Interferes with Reproductive Hormones and Decreases Sperm Counts: A Systematic Review and Meta-Analysis of Epidemiological Studies

Bisphenol A (BPA), an acknowledged endocrine disrupter, is easily exposed to humans via food packaging and container. However, a consensus has not been reached on the extent to which BPA exposure affects the reproductive system. We therefore conducted this systematic review and meta-analysis to elucidate the relationship between BPA exposure and male reproduction-related indicators. Up to October 2023, a comprehensive search was carried out in the PubMed, Embase, Cochrane and Web of Science, and 18 studies were ultimately included. β coefficients from multivariate linear regression analyses were pooled using a random effects model. The results showed that the urinary BPA concentration was negatively correlated with the sperm concentration (β coefficient = -0.03; 95% CI: -0.06 to -0.01; I2 = 0.0%, p = 0.003) and total sperm count (β coefficient = -0.05; 95% CI: -0.08 to -0.02; I2 = 0.0%, p < 0.001). In addition, BPA concentrations were associated with increased sex hormone-binding globulin (SHBG) levels, increased estradiol (E2) levels, and reduced biologically active androgen levels. However, the relationship between an increased risk of below-reference sperm quality and BPA exposure was not robust. This systematic review revealed that BPA exposure disrupts reproductive hormones, reduces sperm counts and may ultimately adversely affect male reproduction.

Rats' testicular toxicity induced by bisphenol A is lessened by crocin via an antiapoptotic mechanism and bumped P-glycoprotein expression

Bisphenol A (BPA) engenders testicular toxicity via hydroxyl free radical genesis in rat striatum and depletion of the endogenous antioxidants in the epididymal sperms. The multi-drug resistance efflux carrier; P-glycoprotein (P-gp) expel the BPA from the testis and is responsible for the testicular protection through the deactivation of numerous xenobiotics. In our study, we investigated whether the BPA-induced testicular toxicity could be circumvented through administration of an antioxidant; crocin (Cr). Implication of P-gp expression was also investigated. Rats administered BPA (10 mg/kg b.w. orally for 14 days), dropped the body weight, testes/body weight ratio, total protein content, testosterone, follicle stimulating hormone, luteinizing hormone, and sperm motility & count, total antioxidant status, glutathione content and antioxidant enzymes (superoxide dismutase and catalase), concomitant with the elevation of the percentage abnormal sperm morphology, as well as testicular lipid peroxides and nitrite/nitrate levels. Histopathological examination showed spermatogenesis disorders after the BPA rats exposure. The immunohistochemical study showed up-regulation of the P-gp as evident by increasing immunoreactivity in interstitial cells, with positive localization in some spermatogonia cells. The BPA-treated rats showed positive immunoreactivity against caspase-3. The co-intake of Cr (200 mg/kg b.w./day, i.p. 14 days) along with the BPA, significantly ameliorated all the mentioned parameters, boosted histopathological image, fell the caspase-3 up-regulation, and perched the P-gp expression. We showed that, Cr promotes P-gp as an approach to nurture the testicles against the BPA toxicity. In conclusion; Cr lessens the oxidative stress conditions to safeguard rats from the BPA-induced testicular toxicity and sex hormones abnormalities, reducing apoptosis and up-regulating P-gp.

Adverse effects of bisphenol A and its analogues on male fertility: An epigenetic perspective

In recent years, there has been growing concern about the adverse effects of endocrine disrupting chemicals (EDCs) on male fertility. Epigenetic modification is critical for male germline development, and has been suggested as a potential mechanism for impaired fertility induced by EDCs. Bisphenol A (BPA) has been recognized as a typical EDC. BPA and its analogues, which are still widely used in various consumer products, have garnered increasing attention due to their reproductive toxicity and the potential to induce epigenetic alteration. This literature review provides an overview of studies investigating the adverse effects of bisphenol exposures on epigenetic modifications and male fertility. Existing studies provide evidence that exposure to bisphenols can lead to adverse effects on male fertility, including declined semen quality, altered reproductive hormone levels, and adverse reproductive outcomes. Epigenetic patterns, including DNA methylation, histone modification, and non-coding RNA expression, can be altered by bisphenol exposures. Transgenerational effects, which influence the fertility and epigenetic patterns of unexposed generations, have also been identified. However, the magnitude and direction of certain outcomes varied across different studies. Investigations into the dynamics of histopathological and epigenetic alterations associated with bisphenol exposures during developmental stages can enhance the understanding of the epigenetic effects of bisphenols, the implication of epigenetic alteration on male fertility, and the health of successive generation.

Non-monotonic effects of Bisphenol A Dimethacrylate on male mouse reproductive system and fertility leads to impaired conceptive performance

As an estrogenic agent, Bisphenol A Dimethacrylate (Bis-DMA) may incite alterations in both the reproductive tract and the neuroendocrine axis, and thus have the potential to affect the proper development, maturity and conceptive performance in animals. We investigated the consequences of 14 weeks of exposure to different concentrations of Bis-DMA on male mouse conceptive performance. Male mice were exposed to Bis-DMA (0, 0.1 mg/L, 1.0 mg/L or 10 mg/L) via drinking water, and the effects on fertility, reproductive organ weights, reproductive hormone levels, sperm counts and testicular histology were assessed. We clearly demonstrate that prolonged exposure of male mice to Bis-DMA negatively affects fertility and reproduction causing significant reductions in sperm counts, non-monotonic effects on serum LH and testosterone levels, increased seminal vesicle weights, lower number of embryonic implantations and viable fetuses, as well as, increased embryonal resorptions in females mated by Bis-DMA treated males. Furthermore, Bis-DMA caused abnormalities in testicular infrastructure with atrophic seminiferous tubules exhibiting intraepithelial vacuolization and disorganization, loss and shedding of germ cells into the lumen, and presence of apoptotic cells. Our data collectively suggest that Bis-DMA adversely affects male fertility and reproduction by interference with normal hormone signaling in the testis, inducing changes in testicular infrastructure and ultimately leading to impaired reproductive function and fertility.

Redox mechanisms of environmental toxicants on male reproductive function

Humans and wildlife, including domesticated animals, are exposed to a myriad of environmental contaminants that are derived from various human activities, including agricultural, household, cosmetic, pharmaceutical, and industrial products. Excessive exposure to pesticides, heavy metals, and phthalates consequently causes the overproduction of reactive oxygen species. The equilibrium between reactive oxygen species and the antioxidant system is preserved to maintain cellular redox homeostasis. Mitochondria play a key role in cellular function and cell survival. Mitochondria are vulnerable to damage that can be provoked by environmental exposures. Once the mitochondrial metabolism is damaged, it interferes with energy metabolism and eventually causes the overproduction of free radicals. Furthermore, it also perceives inflammation signals to generate an inflammatory response, which is involved in pathophysiological mechanisms. A depleted antioxidant system provokes oxidative stress that triggers inflammation and regulates epigenetic function and apoptotic events. Apart from that, these chemicals influence steroidogenesis, deteriorate sperm quality, and damage male reproductive organs. It is strongly believed that redox signaling molecules are the key regulators that mediate reproductive toxicity. This review article aims to spotlight the redox toxicology of environmental chemicals on male reproduction function and its fertility prognosis. Furthermore, we shed light on the influence of redox signaling and metabolism in modulating the response of environmental toxins to reproductive function. Additionally, we emphasize the supporting evidence from diverse cellular and animal studies.

[Association analysis between mixed exposure to phenols and semen quality]

Phenols such as bisphenols, parabens, and triclosan are common environmental endocrine disruptors. Previous epidemiological studies have suggested that phenols may affect semen quality, but the results were inconsistent. In addition, most existing studies have been limited to the effects of a single chemical compound, ignoring the health effects of mixed exposure to multiple chemicals. Thus, we aimed to explore the associations between individual and mixed exposure to phenols and various semen quality parameters. In this study, a rapid and sensitive method was used to determine 18 phenolic compounds in urine samples of 799 volunteers who donated sperm samples to the Shanghai Human Sperm Bank. A spot urine sample was collected from each subject on the day of their clinic visit and stored at -20 ℃ until testing. Urine samples (200 μL) were extracted and added with 20 μL of an internal standard and 50 μL of β-glucuronidase solution. The mixtures were then incubated for 12 h at 37 ℃. After hydrolysis, the samples were extracted twice using ethyl acetate (500 μL). The concentrations of the 18 phenolic compounds were measured using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Semen quality parameters were analyzed using a computer-aided semen analyzer. Multiple linear regressions were used to detect the associations between individual phenol exposure and semen quality parameters. In addition, weighted quantile sum (WQS) models were used to explore the associations between mixed-phenol exposure and semen quality parameters. After adjusting for potential covariates, the results of multiple linear regressions showed that exposure to ethyl paraben (EtP) was significantly negatively associated with sperm concentration and total sperm count (P<0.05). In addition, exposure to mixed phenols was significantly associated with decreased sperm concentration; methyl paraben (MeP) and EtP were identified as the main contributors to this decrease. Thus, phenol exposure may be associated with decreased semen quality in young males, particularly with respect to sperm concentration and total sperm count.

Endocrine-disrupting chemicals: Mainstream recognition of health effects and implications for the practicing internist

Rapidly advancing evidence documents that a broad array of synthetic chemicals found ubiquitously in the environment contribute to disease and disability across the lifespan. Although the early literature focused on early life exposures, endocrine-disrupting chemicals (EDCs) are now understood to contribute substantially to chronic disease in adulthood, especially metabolic, cardiovascular, and reproductive consequences as well as endocrine cancers. The contribution to mortality is substantial, with over 90,000 deaths annually and at least $39 billion/year in lost economic productivity in the United States (US) due to exposure to certain phthalates that are used as plasticizers in food packaging. Importantly, exposures are disproportionately high in low-income and minoritized populations, driving disparities in these conditions. Though non-Hispanic Blacks and Mexican Americans comprise 12.6% and 13.5% of the US population, they bear 16.5% and 14.6% of the disease burden due to EDCs, respectively. Many of these exposures can be modified through safe and simple behavioral changes supported by proactive government action to both limit known hazardous exposures and to proactively screen new industrial chemicals prior to their use. Routine healthcare maintenance should include guidance to reduce EDC exposures, and a recent report by the Institute of Medicine suggests that testing be conducted, particularly in populations heavily exposed to perfluoroalkyl substances-chemicals used in nonstick coatings as well as oil- and water-resistant clothing.

Drivers of divergent assessments of bisphenol-A hazards to semen quality by various European agencies, regulators and scientists

The downward revision of the bisphenol A (BPA) Health-based Guidance Value (HBGV) by the European Food Safety Authority (EFSA) has led to disagreements with other regulatory agencies, among them the German Federal Institute for Risk Assessment (BfR). The BfR has recently published an alternative Tolerable Daily Intake (TDI), 1000-times higher than the EFSA HBGV of 0.2 ng/kg/d. While the EFSA value is defined in relation to immunotoxicity, the BfR alternative TDI is based on declines in sperm counts resulting from exposures in adulthood. Earlier, we had used semen quality deteriorations to estimate a BPA Reference Dose (RfD) of 3 ng/kg/d for use in mixture risk assessments of male reproductive health. We derived this estimate from animal studies of gestational BPA exposures which both EFSA and BfR viewed as irrelevant for human hazard characterisations. Here, we identify factors that drive these diverging views. We find that the fragmented, endpoint-oriented study evaluation system used by EFSA and BfR, with its emphasis on data that can support dose-response analyses, has obscured the overall BPA effect pattern relevant to male reproductive effects. This has led to a disregard for the effects of gestational BPA exposures. We also identify problems with the study evaluation schemes used by EFSA and BfR which leads to the omission of entire streams of evidence from consideration. The main driver of the diverging views of EFSA and BfR is the refusal by BfR to accept immunotoxic effects as the basis for establishing an HBGV. We find that switching from immunotoxicity to declines in semen quality as the basis for deriving a BPA TDI by deterministic or probabilistic approaches produces values in the range of 2.4-6.6 ng/kg/d, closer to the present EFSA HBGV of 0.2 ng/kg/d than the BfR TDI of 200 ng/kg/d. The proposed alternative BfR value is the result of value judgements which erred on the side of disregarding evidence that could have supported a lower TDI. The choices made in terms of selecting key studies and methods for dose-response analyses produced a TDI that comes close to doses shown to produce effects on semen quality in animal studies and in human studies of adult BPA exposures.

Endocrine disrupting chemicals and male fertility: from physiological to molecular effects

The deleterious effects of chemical or non-chemical endocrine disruptors (EDs) on male fertility potential is well documented but still not fully elucidated. For example, the detection of industrial chemicals' metabolites in seminal plasma and follicular fluid can affect efficiency of the gametogenesis, the maturation and competency of gametes and has guided scientists to hypothesize that endocrine disrupting chemicals (EDCs) may disrupt hormonal homoeostasis by leading to a wide range of hormonal control impairments. The effects of EDCs exposure on reproductive health are highly dependent on factors including the type of EDCs, the duration of exposure, individual susceptibility, and the presence of other co-factors. Research and scientists continue to study these complex interactions. The aim of this review is to summarize the literature to better understand the potential reproductive health risks of EDCs in France.

The Correlation of Urine Bisphenol A with Semen Parameters in Men Referred to Infertility Centers: A Cross-Sectional Study

BACKGROUND

Bisphenol A (BPA) is known as an endocrine disruptor that has harmful effects on general health. It is commonly used in various industrial products. In this study we tried to evaluate the amount of BPA in urine samples of the men referred to an infertility center.

MATERIALS AND METHODS

The cross-sectional study population consisted of male partners of infertile couples, who were referred to infertility clinic in Mazandaran, a northern state of Iran. Questionnaires included demographic characteristics, medical history, lifestyle factors, physical examinations. A semen sample and a spot urine sample were taken from each participant. In the initial study group of 240 men, 3 groups were excluded, and 122 men remained for the analysis. Highperformance liquid chromatography (HPLC) was applied to measure the amount of BPA in the urine samples.

RESULTS

BPA was not detected in about half of the samples (53.3%). Multiple linear regression analysis showed that no significant relationship existed between the urine concentrations of BPA, semen parameters and male reproductive hormones. However, in a comparison with semen parameters in people with detectable urine BPA versus nondetectable ones, an inverse association was noticed with sperm concentration. In other parameters, differences were not significant. Smoking had no effects on sperm parameters, but body mass index (BMI) ≥25 reduced the percentage of normal sperm parameters.

CONCLUSION

In most participants, urinary BPA was not detected. Probably in this study low environmental exposure to BPA is the cause of lower urine BPA concentrations compared to other industrially developed countries. Therefore, no overall relationship was observed between BPA level and male infertility.

The Effects of Bisphenol A on Human Male Infertility: A Review of Current Epidemiological Studies

Endocrine disruptor chemicals (EDCs) can have a harmful effect on the human body's endocrine system and thus adversely affect the development, reproduction, neurological, cardiovascular, and immune systems and metabolism in humans and wildlife. According to the World Health Organization, EDCs are mostly man-made and found ubiquitously in our daily lives, notably in pesticides, metals, and additives or contaminants in food and personal care products. Human exposure occurs through ingestion, inhalation, and dermal contact. Bisphenol A (BPA) is a proven EDC capable of mimicking or blocking receptors and altering hormone concentrations and metabolism. Although consumed in low doses, it can stimulate cellular responses and affect the body's functions. In humans, exposure to BPA has been correlated with the onset or development of several diseases. This literature review aimed to verify the effects of BPA on human male infertility using the most recently published literature. Thus, this review allowed us to conclude that this compound seems to have harmful effects on human male fertility, causing changes in hormonal and semen characteristics. However, these conclusions lack more robust and reproducible scientific studies. Even so, and since male infertility prevalence is increasing, preventive measures must be taken to ensure male fertility.

Role of Silica on Clay-Catalyzed Ozonation for Total Mineralization of Bisphenol-A

Catalytic ozonation for the total mineralization of bisphenol-A (BPA) from aqueous solution was investigated in the presence of various silica-based catalysts such as mesoporous silica, acid-activated bentonite (HMt) and montmorillonite-rich materials (Mt) ion-exchanged with Na⁺ and Fe²⁺ cations (NaMt and Fe(II)Mt). The effects of the catalyst surface were studied by correlating the hydrophilic character and catalyst dispersion in the aqueous media to the silica content and BPA conversion. To the best of our knowledge, this approach has barely been tackled so far. Acid-activated and iron-free clay catalysts produced complete BPA degradation in short ozonation times. The catalytic activity was found to strongly depend on the hydrophilic character, which, in turn, depends on the Si content. Catalyst interactions with water and BPA appear to promote hydrophobic adsorption in high Si catalysts. These findings are of great importance because they allow tailoring silica-containing catalyst properties for specific features of the waters to be treated.

Urinary concentration of phthalates and bisphenol A during minipuberty is associated with reproductive hormone concentrations in infant boys

BACKGROUND

The transient postnatal activation of the hypothalamic-pituitary-gonadal hormone axis is termed minipuberty and considered an important developmental period, which is highly sensitive to endocrine disruption. Here, we explore exposure-outcome associations during minipuberty between concentrations of potentially endocrine disrupting chemicals (EDCs) in urine of infant boys and their serum reproductive hormone concentrations.

METHODS

In total, 36 boys participating in the COPENHAGEN Minipuberty Study had data available for both urine biomarkers of target endocrine disrupting chemicals and reproductive hormones in serum from samples collected on the same day. Serum concentrations of reproductive hormones were measured by immunoassays or by LC-MS/MS. Urinary concentrations of metabolites of 39 non-persisting chemicals, including phthalates and phenolic compounds, were measured by LC-MS/MS. Nineteen chemicals had concentrations above the limit of detection in ≥50% of children and were included in data analysis. Associations of urinary phthalate metabolite and phenol concentrations (in tertiles) with hormone outcomes (age- and sex-specific SD-scores) were analysed by linear regression. Primarily, we focused on the EU regulated phthalates; butylbenzyl phthalate (BBzP), di-iso-butyl phthalate (DiBP), di-n-butyl phthalate (DnBP), and di-(2-ethylhexyl) phthalate (DEHP) as well as bisphenol A (BPA). Urinary metabolites of DiBP, DnBP and DEHP were summed and expressed as ∑DiBPm, ∑DnBPm and ∑DEHPm.

RESULTS

Compared to boys in the lowest ∑DnBPm tertile, urinary concentration of ∑DnBPm was associated with concurrent higher luteinizing hormone (LH) and anti-Müllerian hormone (AMH) SD-scores as well as lower testosterone/LH ratio in boys in the middle ∑DnBPm tertile (estimates (CI 95%) 0.79 (0.04; 1.54), 0.91 (0.13; 1.68), and -0.88 (-1.58;-0.19), respectively). Further, higher insulin-like peptide 3 (INSL3) SD-scores and lower DHEAS SD-score in boys in the highest ∑DnBPm tertile (0.91 (0.12; 1.70) and -0.85 (-1.51;-0.18), respectively) were observed. In addition, boys in the middle and highest ∑DEHPm tertile had higher LH (1.07 (0.35; 1.79) and 0.71 (-0.01; 1.43), respectively) and in the highest ∑DEHPm tertile also higher AMH (0.85 (0.10; 1.61)) concentration SD-scores, respectively. Boys in the highest BPA tertile had significantly higher AMH and lower DHEAS concentration compared to boys in the lowest BPA tertile (1.28 (0.54; 2.02) and -0.73 (-1.45; -0.01)), respectively.

DISCUSSION

Our findings indicate that exposure to chemicals with known or suspected endocrine disrupting potential, especially the EU-regulated DnBP, DEHP and BPA, may modify male reproductive hormone concentrations in infant boys suggesting that minipuberty is a critical window sensitive to endocrine disruption.

Prenatal BPA exposure disrupts male reproductive functions by interfering with DNA methylation and GDNF expression in the testes of male offspring rats

BPA is a ubiquitous environmental endocrine-disrupting chemical, and maternal exposure to BPA is associated with impaired male reproductive functions; however, the mechanisms remain to be elucidated. Glial cell line-derived neurotrophic factor (GDNF) plays an important role in maintaining normal spermatogenesis and fertility. However, the effect of prenatal BPA exposure on GDNF expression and its mechanism in the testis has not been reported. In this study, pregnant Sprague-Dawley rats were respectively exposed to 0, 0.05, 0.5, 5, and 50 mg/kg/day BPA via oral gavage from gestational day (GD) 5 to GD 19, with 6 pregnant rats in each group. ELISA, histochemistry, real-time PCR, western blot, and methylation-specific PCR (MSP) were used to detect the sex hormone levels, testicular histopathology, mRNA and protein expression of DNA methyltransferases (DNMTs) and GDNF, and the promoter methylation of Gdnf in the testes of male offspring at postnatal day (PND) 21 and PND 56. Prenatal BPA exposure increased body weight; decreased sperm counts and serum levels of testosterone (T), follicle-stimulating hormone (FSH), and luteinizing hormone (LH); and induced testicular histological damage, which indicated the damage of male reproductive function. Prenatal BPA exposure also upregulated Dnmt1 in 5 mg/kg group and Dnmt3b in 0.5 mg/kg group, but down-regulated Dnmt1 in 50 mg/kg group at PND 21. At PND 56, Dnmt1 was significantly increased in 0.05 mg/kg group but decreased in 0.5, 5, and 50 mg/kg groups, Dnmt3a was decreased, and Dnmt3b was markedly increased in 0.05 and 0.5 mg/kg groups but decreased in 5 and 50 mg/kg groups. The mRNA and protein expression levels of Gdnf were decreased markedly in 0.5 and 50 mg/kg groups at PND 21. And the methylation level of Gdnf promoter was significantly increased in 0.5 mg/kg group, but decreased in 5 and 50 mg/kg groups at PND 21. In conclusion, our study indicates that prenatal BPA exposure disrupts male reproductive functions, interferes with the expression of DNMTs, and decreases Gdnf expression in the testes of male offspring. Gdnf expression may be regulated by DNA methylation; however, the detailed mechanism needs to be further investigated.

Re-evaluation of the risks to public health related to the presence of bisphenol A (BPA) in foodstuffs

In 2015, EFSA established a temporary tolerable daily intake (t-TDI) for BPA of 4 μg/kg body weight (bw) per day. In 2016, the European Commission mandated EFSA to re-evaluate the risks to public health from the presence of BPA in foodstuffs and to establish a tolerable daily intake (TDI). For this re-evaluation, a pre-established protocol was used that had undergone public consultation. The CEP Panel concluded that it is Unlikely to Very Unlikely that BPA presents a genotoxic hazard through a direct mechanism. Taking into consideration the evidence from animal data and support from human observational studies, the immune system was identified as most sensitive to BPA exposure. An effect on Th17 cells in mice was identified as the critical effect; these cells are pivotal in cellular immune mechanisms and involved in the development of inflammatory conditions, including autoimmunity and lung inflammation. A reference point (RP) of 8.2 ng/kg bw per day, expressed as human equivalent dose, was identified for the critical effect. Uncertainty analysis assessed a probability of 57-73% that the lowest estimated Benchmark Dose (BMD) for other health effects was below the RP based on Th17 cells. In view of this, the CEP Panel judged that an additional uncertainty factor (UF) of 2 was needed for establishing the TDI. Applying an overall UF of 50 to the RP, a TDI of 0.2 ng BPA/kg bw per day was established. Comparison of this TDI with the dietary exposure estimates from the 2015 EFSA opinion showed that both the mean and the 95th percentile dietary exposures in all age groups exceeded the TDI by two to three orders of magnitude. Even considering the uncertainty in the exposure assessment, the exceedance being so large, the CEP Panel concluded that there is a health concern from dietary BPA exposure.

Sperm parameters in the Great Dane: Influence of age on semen quality

Not all sires have sperm suitable for chilled or frozen storage, and success in artificial insemination (AI) varies highly among individual dogs and breeds. Fertilizing potential is further complicated as sperm quality declines with the aging process. Due to the rapidity of aging and senescence in large breed dogs, associated health and fertility changes may be observed over a shorter period, though this period remains undefined for any breed. Working with a population of purebred Great Danes (GD), our aims were (1) to characterize the distribution of a series of sperm parameters, (2) to distinguish sources of variation in sperm quality within this rapidly aging breed, and (3) to identify changes in sperm quality that may accompany aging. Ejaculates collected from young, middle-aged, and senior Great Dane dogs (n = 50) were evaluated for semen volume, total sperm number and viability, and reactive oxygen species (ROS), in addition to sperm morphology and kinematic parameters. Total testicular volume was also determined using ultrasonography. Testicular volume was not a predictor of sperm production in the GD, however, significant differences between coat colors were identified. Age was negatively associated with total motility, progressive motility, and amplitude of lateral head displacement (ALH) (p < .05). We identified significant relationships between GD male age and TM, PM, and immotility with -9.9%, -9.0%, and +8.3% change per year of age, respectively, which support the anecdotal reports of decline of the fertility with the advance of age in this breed. Sperm of younger GD dogs aged 12 ≤ x < 24 months had significantly higher TM, PM, ALH, and nonlinear motility (p < .05) than older dogs (x ≥ 48 months). High ROS levels were positively associated with TM and PM, average pathway distance (DAP) and straight line distance (DSL), average pathway velocity (VAP), straight line velocity (VSL), and the presence of hairpin tails (p < .05). While age and ROS have significant influences on sperm parameters in the GD, the influence of selection for breed specific phenotypes could help explain the functional significance of the diversity among GD males.

A Case-Control Study on the Effects of Plasticizers Exposure on Male Fertility

Male infertility is a serious concern for public health, and the possible role of exposure to plasticizers such as phthalates and bisphenol A in contributing to the condition is widely debated. We have herein enrolled 155 infertility cases attending an infertility center and 211 controls (fathers of a spontaneously conceived newborn) to investigate this issue. The urinary levels of seven phthalates and BPA were analyzed through HPLC/MS/MS. All data were statistically elaborated considering information about clinical situation, life habits, occupational activity, and, for cases, semen parameters (volume, sperm concentration, total count of spermatozoa, and sperm motility). Results showed significantly higher urinary concentrations for all the phthalates in cases compared to controls, except for monoethylphthalate and BPA. In total, 90.07% of cases had sperm motility lower than the WHO reference value (2010), while 53.69%, 46.31%, and 16.56% had sperm total number, concentration, and volume, respectively, out of the reference range. Regarding the possible source of exposure, the use of scents seems to be a significant source of DEP (diethylphthalate). When considering occupational settings, industrial workers, dental technicians, artisans, and farmers using chemicals showed higher risk (OR = 2.766, 95% CI 1.236-6.185), particularly in relation to DnBP (di-n-butyl phthalate) and DEHP (di-ethyl-hexyl phthalate) exposure. No clear quantitative correlation between specific plasticizers and sperm parameters could be demonstrated but these findings call for future studies about the risks associated with exposure to their mixture.

Associations between urinary concentrations of bisphenols and serum concentrations of sex hormones among US. Males

BACKGROUND

Bisphenol A (BPA) exposure and its structural analogs (BPS and BPF) might cause endocrine alterations and adverse physiological effects. Few studies to date have directly explored the association between its structural analogs (BPS, BPF) and sex hormones in adult male participants. Therefore, we aimed to assess the associations between BPA, BPS, BPF, and sex hormones in American adult men.

METHODS

We used data from the U.S. National Health and Nutrition Examination Survey 2011-2016. We excluded participants without data available on sex hormones and urinary bisphenols. Furthermore, participants consuming sex hormone medications were excluded. Multivariable regression models were performed to assess the association between bisphenols and sex hormones.

RESULTS

In this study, 2367 participants were included. Of 2367, in 1575 participants, the data on BPS and BPF were available. We found that a per unit increase in BPF was associated with 0.575 ng/dL higher total testosterone (TT) (Model 2: 95% CI: 0.047, 1.103, P = 0.033). However, there was no significant association between BPA or BPS and TT. Furthermore, increased BPA and BPS levels were associated with higher levels of sex hormone-binding globulin (SHBG) (Model 2: β = 0.364, 95% CI: 0.158, 0.571; β = 0.25, 95% CI: 0.071, 0.429, respectively). Additionally, participants in the highest BPA exposure quartile (quartile 4) had 4.072 nmol/L higher levels of SHBG than those in quartile 1 (Model 2: 95% CI: 0.746, 7.397, P = 0.017; P for trend =0.005). Both BPA and BPS were negatively associated with free testosterone (FT, nmol/L) after full adjustment (Model 2, β = - 0.01%, P = 0.0211, P = 0.0211; Model 2, β = - 0.01%, P = 0.0258, respectively). However, BPF was positively associated with FT (Model 2, β = 0.0029%, P = 0.0028).

CONCLUSION

Our study indicated that exposure to both BPA and its substitutions could alter sex hormone levels. This finding supports the possibility that human exposure to bisphenols at environmental levels might affect the endogenous hormone balance.

Susceptibility of male reproductive system to bisphenol A, an endocrine disruptor: Updates from epidemiological and experimental evidence

Bisphenol A (BPA) is an omnipresent environmental pollutant. Despite being restrictions in-force for its utilization, it is widely being used in the production of polycarbonate plastics and epoxy resins. Direct, low-dose, and long-term exposure to BPA is expected when they are used in the packaging of food products and are used as containers for food consumption. Occupationally, workers are typically exposed to BPA at higher levels and for longer periods during the manufacturing process. BPA is a known endocrine disruptor chemical (EDC), that causes male infertility, which has a negative impact on human life from emotional, physical, and societal standpoints. To minimize the use of BPA in numerous consumer products, efforts and regulations are being made. Despite legislative limits in numerous nations, BPA is still found in consumer products. This paper examines BPA's overall male reproductive toxicity, including its impact on the hypothalamic-pituitary-testicular (HPT) axis, hormonal homeostasis, testicular steroidogenesis, sperm parameters, reproductive organs, and antioxidant defense system. Furthermore, this paper highlighted the role of non-monotonic dose-response (NMDR) in BPA exposure, which will help to improve the overall understanding of the harmful effects of BPA on the male reproductive system.

Physiological, biochemical, and hormonal changes in rats exposed to bottled water left in a hot car and the freezer

The aim of this study was to investigate the effects of bottled water left in the car and those left in the refrigerator on the physiological and biochemical parameters of male rats. Eighteen male albino rats were randomly divided into control, warmed bottled water (WBW), and cooled bottled water (CBW) groups. The concentrations of bisphenol A (BPA) and antimony (Sb) in the water samples were measured. Results showed that the levels of BPA and Sb were higher in bottled water left in the car and those kept at room temperature (control), relative to the bottled water samples kept in the fridge. Bodyweight, some metabolic indicators, cTnT and CRP levels, hematological parameters, testosterone level, and sperm quality were significantly affected by storage conditions. These results indicate that storage conditions can potentially affect the quality of bottled water, which in turn can affect the biological parameters of living organisms. Moreover, since the concentrations of BPA and Sb were least in bottled water kept in the refrigerator, we recommend that manufacturers and households should endeavor to keep bottled water under cold storage.

Bisphenol A exposure induces testicular oxidative damage via FTO/m6A/Nrf2 axis during postnatal development in mice

Bisphenol A (BPA), a commonly used plasticizer in the production of polycarbonate plastics and epoxy resins, has been shown to induce male reproductive toxicity. However, the effects of BPA exposure on early testicular development have not been thoroughly studied, and the underlying mechanism is yet to be elucidated. In the current study, neonatal male mice were exposed to BPA at 0, 0.1, and 5 mg/kg, respectively, by daily subcutaneous injection during postnatal day (PND) 1-35 to explore its effects on testicular development at PND 36 (the end of the first round of spermatogenesis). Morphological analyses showed that BPA exposure significantly induced apoptosis of testicular cells (p < 0.01 and p < 0.001) and reduced the thickness of seminiferous epithelium (p < 0.01). In addition, BPA exposure significantly decreased the total antioxidant capacity of testes and levels of transcription factor Nrf2 as well as its downstream antioxidant molecules of NQO1 and GPx-1 (p < 0.05 and p < 0.01). Furthermore, global m6A modifications of mRNAs were upregulated accompanied by declined m6A demethylase (FTO) in the testes of BPA groups (p < 0.05 and p < 0.01). MeRIP-quantitative real-time polymerase chain reaction (qPCR) demonstrated that BPA exposure markedly increased the m6A modification of Nrf2 mRNA (p < 0.05 and p < 0.01). These findings suggest that upregulation of m6A induced by inhibited FTO may be involved in BPA-induced testicular oxidative stress and developmental injury during postnatal development, which provides a new idea to reveal the mechanism underlying BPA interfering with testicular development.

Benzophenones, bisphenols and other polychlorinated/phenolic substances in Danish infants and their parents - including longitudinal assessments before and after introduction to mixed diet

BACKGROUND

Humans are widely exposed to chemicals with known or suspected endocrine disrupting effects. Among those are several benzophenones, bisphenols and other phenols commonly used in consumer products.

OBJECTIVES

To provide human biomonitoring data from young families including infants and their parents as well as longitudinal data of infants exclusively breastfed versus on mixed diet.

METHOD

Twenty-two benzophenones, bisphenols and other phenols, were measured in urine sample sets collected from more than 100 infants and their parents (the TRIO study) and in paired samples from 61 infants when exclusively breastfed and after introduction of mixed diet (the FOOD study).

RESULTS

Twelve out of 22 substances were detectable in more than half of the urine samples from infants, mothers or fathers. Large variation in excreted levels of almost all the substances were observed. The TRIO study showed that infants had comparable or even significantly higher daily urinary excretion (DUE) of benzophenone, 4-hydroxy-benzophenone, bisphenol A, bisphenol S, triclosan and 2-phenylphenol than their parents. In the FOOD study, exclusively breastfed infants had higher or similar DUE of triclosan and benzophenones compared to when they received mixed diet. Urinary levels of triclosan and the benzophenones, BP-1 and BP-3 were significantly correlated between all trio members, indicating exposure from the same sources at home. For triclosan, BP-1 and BP-3, the within family variation was lower than between families in the TRIO study. Many substances were positively correlated both within infants and parents, indicating that some families were exposed to several of these substances concurrently.

CONCLUSION

Participants in this study excreted relatively low chemical levels, however, simultaneous exposure to several chemicals with endocrine disrupting abilities is of concern due to the dose-additive effects of these substances in combination with other chemicals.

Bisphenol A analogues in associations with serum hormone levels among reproductive-aged Chinese men

BACKGROUND

Bisphenol A (BPA) as an endocrine disrupting chemical has been shown to alter reproductive endocrine function, but little is known on its analogues such as bisphenol F (BPF) and bisphenol S (BPS) with increasing usage and exposure.

OBJECTIVE

To explore the associations between exposures to BPA, BPF and BPS and serum reproductive hormones among reproductive-aged Chinese men.

METHODS

We measured BPA, BPF and BPS concentrations in repeated urine samples and multiple reproductive hormones in the serum samples collected from 462 men attending an infertility clinic in Wuhan, China. Linear regression models were applied to assess the associations between averaged urinary BPA, BPF and BPS levels and serum hormone concentrations, and restricted cubic spline (RCS) models were further utilized to explore potential non-linear associations. We also examined potential modifying effects by age and body mass index (BMI).

RESULTS

There was little evidence of associations between BPA exposure and altered reproductive hormones. However, we found that elevated BPF and BPS exposures were in negative associations with estrogen (E2) levels and E2/T (total testosterone) ratio (all P for trends < 0.05), and that elevated BPS exposure was negatively associated with SHBG levels (P for trend = 0.09). Based on the RCS models, these linear negative associations except that between BPS exposure and E2/T ratio were further confirmed. In stratified analyses, BPF and BPS exposures in relation to reduced E2 and E2/T ratio were more pronounced among men aged > 30 years, whereas their associations with reduced SHBG levels were more pronounced among men aged ≤ 30. Also, BPS exposure in negative association with FSH only emerged among men with BMI ≥ 24 kg/m² (P for interaction = 0.03).

CONCLUSION

BPF and BPS exposures were negatively associated with male serum E2, E2/T ratio and SHBG levels, and these associations varied by age and BMI.

From Oxidative Stress to Male Infertility: Review of the Associations of Endocrine-Disrupting Chemicals (Bisphenols, Phthalates, and Parabens) with Human Semen Quality

Exposure to endocrine-disrupting chemicals (EDCs) may result in oxidative stress and endocrine system disturbance, which can have an impact on human reproduction and development. In male reproductive health, EDCs have been related to impaired reproductive function and male infertility, altered fetal development, and testicular germ-cell, prostate, and breast cancers. We conducted an electronic search using PubMed on endocrine disruptors related to oxidative stress and male infertility, and evaluated their association with endocrine-disrupting chemicals (bisphenols, phthalates, and parabens) in 25 articles. Higher levels of urinary bisphenols showed correlation with impaired semen quality and increased DNA damage. Considering phthalates and their metabolites, all studies found a positive association between urinary levels of phthalates and at least one semen parameter indicative of low semen quality; some studies also revealed sperm DNA damage. The studies on parabens less often revealed correlation of urinary parabens concentrations with a decrease in sperm count, as well as motility and DNA damage. Moreover, EDCs can elevate ROS production and lipid peroxidation, increase apoptosis, induce epigenetic modifications, and change the Y:X sperm chromosome ratio and sperm protein composition. Our review revealed detrimental effects of EDCs on semen quality and sperm DNA integrity-especially in BPA and phthalates, but also in parabens.

Exposure profiles and predictors of a cocktail of environmental chemicals in Chinese men of reproductive age

Personal care products, such as additives, have raised widespread concerns about the potential threat to male reproductive health. The spermatogenesis in humans lasts for approximately 90 days, the average levels of these chemicals remain unclear during spermatogenesis. In our study, we pooled urine samples from each man during the days of 1-15, 16-31, 32-63, and ≥64, and examined exposure to 48 typical additive chemicals. By principal component analysis (PCA), k-means clustering, and Spearman's rank correlations, we then identified 6 PC scores and 4 clusters based on profiles of these chemicals. Some industrial, commercial or structural similar chemicals (e.g., phthalates) were significantly correlated compared to unrelated chemicals (e.g., benzophenone). PCA scores were associated with individual lifestyles (e.g., household income, tea consumption, and drinking tap water). Distinct exposure components and exposure patterns of personal care products may help the reproductive health assessment of men. We suggested more concerns for widespread exposure to these chemicals for men.

The impact of preconceptional exposure of F0 male mice to bisphenol A alone or in combination with X-rays on the intrauterine development of F2 progeny

Bisphenol A (BPA) is used for the production of polycarbonates and epoxy resins. Exposure to chemical and physical environmental factors may influence the health of exposed individuals, and of the next generations. This paper describes the prenatal effects in the F2 generation of mice after exposure of F0 pubescent or mature males to BPA (5 mg/kg bw, 10 mg/kg bw, 20 mg/kg bw), X-rays (0.05 Gy) or a combination of both factors in low doses (0.05 Gy + 5 mg/kg bw BPA) for 8 weeks. F1 males were mated with females from the same group but from a different litter. The females were sacrificed before parturition and examined for the number of implantations, live foetuses, as well as early and late post-implantation deaths. The fertility of males and the percentage of pregnant females in each group were also assessed. Exposure of pubescent F0 males to 10 mg/kg bw of BPA decreased the frequency of fertile males. Following exposure of pubescent males, the frequency of pregnant females decreased in the groups of 10 mg/kg bw and 20 mg/kg bw of BPA, whereas after exposure of adult F0 males in the groups of 5 mg/kg bw and 20 mg/kg bw of BPA, no significant changes in the frequency of total, live and dead implantations in all the experimental groups were found. The results observed in regard to prenatal development of the F2 generation suggest that sperm of the sons of F0 pubescent males exposed to BPA contains genetic defects that affect the possibility of fertilization. The results of both pubescent and mature males exposed to BPA showed that fertilized eggs died before implantation, probably due to defects induced in the sperm. This confirmed that BPA induced transgenerational effects in male germ cells.

Patterns of environmental exposure to phenols in couples who plan to become pregnant

Phenols are widely used in consumer products and known for their reproductive toxicities. Little is known regarding the environmental exposure to phenols in couples prior to conception, a key period affecting fertility. We measured the urinary concentrations of six parabens and seven bisphenols in 903 pre-conception couples in China. We investigated the occurrence, distribution, source and health risk of phenols in husbands and wives separately, and the correlation and difference in phenol concentrations between couples. Similar distribution profiles of urinary phenols were observed between females and males. Methyl 4-hydroxybenzoate (MeP) and bisphenol A (BPA) were the predominant compounds. The level of urinary phenols in our population was mostly lower than the global levels. Exposure to phenols was linked to processed food and personal care products. The correlations between phenols in males and females were moderate (0.218-0.686), while the correlation in phenols between husband and wife was low (0.009-0.215). Female had a significantly higher urinary phenol levels than male (P < 0.05). Urinary phenols in couples were associated with family income, type of drinking water and frequency of household cleaning. Household factors accounted for ≤1.5% of variance in phenol levels between couples, suggesting that individual variations may be the major factor. Risk assessment showed that exposure to phenols posed a low hazard to 17.5% of the couples in our population. Our findings provide important evidence of environmental exposure to phenols in couples of child-bearing age.

Associations between urinary bisphenol A and its analogues and semen quality: A cross-sectional study among Chinese men from an infertility clinic

Human studies on association between bisphenol A (BPA) exposure and semen quality, mostly based on single urinary measurement, are inconsistent. There is limited human evidence on BPA analogues such as bisphenol F (BPF) and bisphenol S (BPS), and little is known on potential effects of bisphenol mixtures. We aimed to explore whether individual or mixtures of BPA, BPS and BPF assessed in repeated urinary measurements were associated with semen quality among 984 Chinese men from an infertility clinic. We found that higher BPA exposure was associated with increased odds ratios (ORs) of having below-reference sperm concentration, total sperm count, progressive motility and total motility (all P for trends < 0.05). Higher BPS exposure was associated with increased ORs of having below-reference progressive motility and total motility (both P for trends = 0.02); the ORs comparing extreme quartiles were 1.62 (95% CI: 1.07, 2.43) and 1.57 (95% CI: 1.06, 2.33), respectively. Elevated risks for each outcome were also observed when bisphenol mixtures were at ≥ 55th percentiles. For semen quality parameters modeled as continuous outcomes, inverse associations with individual BPA and BPS and bisphenol mixtures were still estimated. Our results suggested that higher exposure to individual BPA and BPS and bisphenol mixtures were associated with impaired semen quality.

Environmental pollution, a hidden culprit for health issues

The environmental and health impacts from the massive discharge of chemicals and subsequent pollution have been gaining increasing public concern. The unintended exposure to different pollutants, such as heavy metals, air pollutants and organic chemicals, may cause diverse deleterious effects on human bodies, resulting in the incidence and progression of different diseases. The article reviewed the outbreak of environmental pollution-related public health emergencies, the epidemiological evidence on certain pollution-correlated health effects, and the pathological studies on specific pollutant exposure. By recalling the notable historical life-threatening disasters incurred by local chemical pollution, the damning evidence was presented to criminate certain pollutants as the main culprit for the given health issues. The epidemiological data on the prevalence of some common diseases revealed a variety of environmental pollutants to blame, such as endocrine-disrupting chemicals (EDCs), fine particulate matters (PMs) and heavy metals. The retrospection of toxicological studies provided illustrative clues for evaluating ambient pollutant-induced health risks. Overall, environmental pollution, as the hidden culprit, should answer for the increasing public health burden, and more efforts are highly encouraged to strive to explore the cause-and-effect relationships through extensive epidemiological and pathological studies.

Prenatal exposure to phenols and benzophenones in relation to markers of male reproductive function in adulthood

INTRODUCTION

Environmental exposure during fetal life may disrupt testicular development. In humans, a limited number of studies have investigated whether these adverse effects persist into adulthood. Using data from a prospective, population-based birth cohort study, The Copenhagen Mother-Child cohort, the objective was to assess if there is an association between fetal exposure to selected phenols and benzophenones and markers of testicular function in adult men.

METHODS

Pregnant women were recruited in 1997-2001. Their sons were examined clinically at 18-20 years of age, with focus on adult markers of reproductive function (anogenital distance (AGD), semen quality and reproductive hormones). In total, 101 18-20-year-old men were included, whose mothers during pregnancy had a serum sample drawn and analyzed for bisphenol A (BPA) and seven other simple phenols, as well as six benzophenones. To investigate the association between chemical levels (in tertiles, T1-T3) in relation to markers of reproductive function, univariate and multiple linear regression analyses were performed.

RESULTS

In fully adjusted analyses, increased levels of luteinizing hormone (LH) were observed with higher fetal exposure to BPA (percentage difference (95%CI)) (T2: 12% (-8%,36%) and T3: 33% (10%,62%), compared to T1) and benzophenone-3 (BP-3) (T2: 21% (-2%,49%), T3: 18% (-4%,45%)), while no clear association was seen to total testosterone (TT). Higher levels of BPA and BP-3 were associated with a lower TT/LH ratio, although only significant for BPA (p-trend=0.01). No associations were seen to AGD or markers of semen quality.

CONCLUSION

In conclusion, high exposure to BPA and BP-3 was associated with a compensated reduced Leydig cell function but no other changes in markers of reproductive health. As maternal levels of BPA and BP-3 were not correlated, separate effects may be at play. Larger studies on long-term reproductive consequences of prenatal exposures are warranted to validate our findings.

Men´s reproductive alterations caused by bisphenol A and its analogues: a review

Male reproductive functions are an important area affecting men´s overall health and well-being. However, during the last years, there has been observed increasing incidence of male reproductive issues. The radical growth has been recorded parallelly with a massive expanse of industrialization and agricultural chemigation. Many groups of experts have begun to identify several potential factors and substances that may have adverse effects on men´s reproductive health. Since then, xenobiotics have become a major concern of many scientific studies. There is evidence that most of them have multigenerational and transgenerational effects on reproductive health, which is a serious problem for our population. Bisphenol A could be considered as one of the most studied endocrine disruptors. Until now, several negative effects of bisphenol A were associated with reduced weight testes, histological alterations, impairment spermatogenesis, and steroidogenesis as well as with testes or prostate cancer. Due to convincing evidence, bisphenol A has been started to replace by its analogues such as bisphenol B, S, F, in order to eliminate and suppress the risk of exposure to bisphenol A. However, it seems that a lack of toxicological analyses allows using of these hazardous substances in daily life. Their harmful effect was confirmed by the animal in vitro and in vivo models, while the epidemiological studies monitoring the impact of bisphenol analogues on men's reproductive health are markedly limited. This review provides information about the effects of bisphenol on reproductive health in men. At the same time, it is focused on physiological aspects of sperm viability, steroid hormone secretion, sperm motility, or testes histology in relation to bisphenols exposure.

Association between urinary bisphenol A concentrations and semen quality: a meta-analytic study

Although preclinical research has revealed disrupting effects on male reproductive functions of bisphenol A (BPA), as yet clinical studies have led to inconsistent results. The present meta‑analysis aims to establish the existence and the extent of the association between BPA exposure and semen quality. A thorough search of PubMed, Scopus and Web of Science databases was carried out. Only studies reporting data from multivariable linear regression analyses (β-coefficients with 95% CI), assessing the association between urinary levels of BPA and standard semen parameters were included. Nine studies provided information about an overall sample of 2,399 men. Only the negative association between urinary BPA levels and sperm motility reached statistical significance (pooled β-coefficient = -0.82; 95% CI: -1.51 to -0.12, p = 0.02; P_{for heterogeneity} = 0.1, I² = 42.9%). Yet, such a significance was lost after data adjustment for publication bias, as well as at the sensitivity analysis, when each of the two studies that contributed most to the overall estimate was excluded. In conclusion, the overall estimates of data produced by clinical studies point to a clinically negligible, if any, association between urinary BPA concentrations and semen quality. Further studies in workers at high risk of occupational exposure are warranted to corroborate the herein revealed weak correlation with a worse sperm motility.

The Association between Bisphenol A, Steroid Hormones, and Selected MicroRNAs Levels in Seminal Plasma of Men with Infertility

Bisphenol A (BPA), the most common endocrine-disrupting chemical, has been associated with male reproductive dysfunctions. Recently, it has been shown that BPA may also affect miRNAs expression. Herein, we aimed to evaluate the association of BPA levels with steroid hormone concentration and circulating miRNAs levels to investigate the potential direct effect of BPA on homeostasis in the testis environment. The level of BPA in the seminal plasma of azoospermic men was significantly higher compared to the healthy control. The concentrations of estradiol (E2) and androstenedione (A) were significantly decreased in the seminal plasma of azoospermic men compared to the normospermic men. The levels of miR-let-7a, miR-let-7b, and miR-let-7c were significantly up-regulated, and the level of miR-518f was significantly down-regulated in the seminal plasma of the azoospermic men compared to the healthy control. The level of BPA correlated negatively with sperm concentration and normal semen morphology. A significant positive correlation was found between BPA levels and miR-let-7a and miR-let-7c levels, whereas BPA negatively correlated with miR-518f levels. Our results suggest that BPA may negatively affect sperm quality. Moreover, BPA correlated with the miR-let-7a, miR-let-7c, and miR-518f levels in seminal plasma, which suggests that BPA may act directly in seminal plasma, affecting the testicular environment.

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.

Bisphenol A and Its Analogues Deteriorate the Hormones Physiological Function of the Male Reproductive System: A Mini-Review

BPA is identified as an endocrine-disrupting chemical that deteriorates the physiological function of the hormones of the male reproductive system. Bisphenol F (BPF), bisphenol S (BPS), and bisphenol AF (BPAF) are actively explored as substitutes for BPA and are known as BPA analogues in most manufacturing industries. These analogues may demonstrate the same adverse effects as BPA on the male reproductive system; however, toxicological data explaining the male reproductive hormones' physiological functions are still limited. Hence, this mini-review discusses the effects of BPA and its analogues on the physiological functions of hormones in the male reproductive system, focusing on the hypothalamus-pituitary-gonad (HPG) axis, steroidogenesis, and spermatogenesis outcomes. The BPA analogues mainly show a similar negative effect on the hormones' physiological functions, proven by alterations in the HPG axis and steroidogenesis via activation of the aromatase activity and reduction of spermatogenesis outcomes when compared to BPA in in vitro and in vivo studies. Human biomonitoring studies also provide significant adverse effects on the physiological functions of hormones in the male reproductive system. In conclusion, BPA and its analogues deteriorate the physiological functions of hormones in the male reproductive system as per in vitro, in vivo, and human biomonitoring studies.

The Male Reproductive System and Endocrine Disruptors

The male reproductive system is exposed to a great number of chemical substances which can interfere with the normal hormonal milieu and reproductive function; these are called endocrine disruptors (EDs). Despite a growing number of studies evaluating the negative effects of EDs, their production is continuously growing although some of which have been prohibited. The prevalence of poor semen quality, hypospadias, cryptorchidism, and testicular cancer have increased in the last decades, and recently, it has been postulated that these could all be part of a unique syndrome called testicular dysgenesis syndrome. This syndrome could be related to exposure to a number of EDs which cause imbalances in the hormonal milieu and oestrogenic over-exposure during the foetal stage. The same EDs can also impair spermatogenesis in offspring and have epigenetic effects. Although studies on animal and in vitro models have raised concerns, data are conflicting. However, these studies must be considered as the basis for future research to promote male reproductive health.

Physiologically detectable bisphenol A impairs human sperm functions by reducing protein-tyrosine phosphorylation

BACKGROUND

Bisphenol A (BPA), a widely used plastic monomer and plasticizer, is detectable in blood, urine and semen of a healthy people, with concentrations ranging from 0.1 nM to 10 nM. It has been shown that in vitro exposure of BPA as low as 0.001 nM could significantly inhibited mouse sperm motility and acrosome reaction. However, it is still unclear whether BPA at those physiologically detectable concentration affects human sperm.

METHODS

The effects of different concentrations of BPA (0, 10^-3, 10^-2, 10^-1, 10, 10³ nM) on sperm functions were examined, including human sperm viability, kinematic parameters, hyperactivation and capacitation.

RESULTS

BPA caused a remarkable decline in human sperm viability, motility and progressive motility, hyperactivation, capacitation and progesterone-induced acrosome reaction. Mechanism studies showed that BPA could suppress the protein tyrosine phosphorylation level of human sperm, but had no effect on sperm calcium signaling.

CONCLUSIONS

Physiologically detectable concentrations of BPA may impair human sperm functions via suppressing protein tyrosine phosphorylation of human sperm, implying that environmental pollution of BPA might be a factor contributing to male infertility.

Bisphenol A and male murine reproductive system: finding a link between plasticizer and compromised health

The global burden of male infertility is rising at an alarming rate affecting the lives of millions in terms of physical, emotional and societal perspectives. Among several existing endocrine disrupting chemicals, bisphenol A (BPA) has been reported by many to inflict male reproductive toxicity in different experimental models, especially in mice. This review article critically discusses the overall reproductive toxicity of BPA with a special note to its ubiquitous existence, contamination route, effects on the reproductive system and toxicity mechanisms in male mice. Disturbed redox status in germ cells and spermatozoa plays a pivotal role in BPA induced male reproductive toxicity. In this context, the involvement of mitochondria and endoplasmic reticulum is also of grave importance. Induction of caspase-dependent apoptosis is the extreme consequence that leads to deterioration of cellular parameters. Besides the oxidative cellular and histoarchitectural damages, perturbed endocrine regulation, subsequent impaired hormonal and cellular genesis program, epigenetic alterations and inflammation cumulatively reflect poor sperm quality leading to compromised reproduction. Moreover, several key issues have also been highlighted that, if addressed, will strengthen our understanding of BPA mediated male reproductive toxicity.

Alterations of Kiss 1 receptor, GnRH receptor and nuclear receptors of the hypothalamo-pituitary-ovarian axis following low dose bisphenol-A exposure in Wistar rats

Bisphenol A is a chemical used primarily as a monomer in the production of polycarbonate plastics and epoxy resins. It is a synthetic chemical compound that is produced in billions of pounds annually, and tagged as an endocrine disruptor. Bisphenol A is a high production synthetic chemical compound that is used in the production of many consumables and equipments of daily consumption and use by man. Growing interest in possible health threats posed by endocrine disrupting chemicals (bisphenol-A inclusive), as these substances are in our environment, food, and many consumer products. Therefore, this study aims to determine bisphenol-A effects on the hypothalamo-pituitary-ovarian axis, and role of melatonin in this regard. Forty-two Wistar rats were bred, grouped into 7, with each group consisting of 6 rats. Experimental groups were administered low and high doses of bisphenol-A and melatonin, starting from day 19, and was continued for 7 weeks orally. They were left to develop into full adults and were sacrificed on day 120±4 days. Blood samples, hypothalamus, pituitary and ovarian tissues were excised for biochemical and tissue antioxidants assays as well as genetic studies. Results show elevated gonadotropin and androgen levels. There was disruption of reactive oxygen species in the ovarian tissues, as well as alterations in the expression of genes that regulate reproduction at the hypothalamus and pituitary levels. Conclusion of early exposure to bisphenol-A is associated with prolonged duration of disruption of reproductive functions in female Wistar rats, which persist long after cessation of the exposure. Melatonin antioxidant effects give some promising outturns against bisphenol-A induced toxicities.

Fighting Bisphenol A-Induced Male Infertility: The Power of Antioxidants

Bisphenol A (BPA), a well-known endocrine disruptor present in epoxy resins and polycarbonate plastics, negatively disturbs the male reproductive system affecting male fertility. In vivo studies showed that BPA exposure has deleterious effects on spermatogenesis by disturbing the hypothalamic–pituitary–gonadal axis and inducing oxidative stress in testis. This compound seems to disrupt hormone signalling even at low concentrations, modifying the levels of inhibin B, oestradiol, and testosterone. The adverse effects on seminal parameters are mainly supported by studies based on urinary BPA concentration, showing a negative association between BPA levels and sperm concentration, motility, and sperm DNA damage. Recent studies explored potential approaches to treat or prevent BPA-induced testicular toxicity and male infertility. Since the effect of BPA on testicular cells and spermatozoa is associated with an increased production of reactive oxygen species, most of the pharmacological approaches are based on the use of natural or synthetic antioxidants. In this review, we briefly describe the effects of BPA on male reproductive health and discuss the use of antioxidants to prevent or revert the BPA-induced toxicity and infertility in men.

Effects of Bisphenol A Released From Composite Fillings on Reproductive Hormone Levels in Men

Objectives

Composite resins are the most preferred filling material because of their excellent aesthetic qualities. However, a filling material should also be biocompatible as well as aesthetic. The aim of this study was to determine the serum and saliva bisphenol-A (BPA) levels and to examine the effects of serum BPA on reproductive hormone levels after healthy men were treated with composite fillings.

Methods

Eighteen healthy males each received 2 composite restorations. Saliva and blood samples of subjects were collected before resin application and 1 day and 1, 3, and 5 weeks after the resin was applied. BPA amounts in samples were detected using high-performance liquid chromatography (HPLC). Serum gonadotropins, testosterone, sex hormone binding globulin, free androgen index, and oestrogen levels were measured with radioimmunological assay kits. Statistical analysis of data was made using Friedman, Wilcoxon signed ranks and Mann-Whitney U tests (α = 0.05).

Results

The amount of BPA released from composite resins over time was not significantly elevated in either saliva or serum (P > 0.5). In addition, serum BPA levels were significantly higher than saliva BPA levels for both composites (P < .05), but saliva and serum BPA levels were not statistically different when comparing the 2 composites (P > .05).

Conclusions

BPA from composite resins used in this study did not significantly alter serum hormone levels.