Exposure of BPA and its alternatives like BPB, BPF, and BPS impair subsequent reproductive potentials in adult female Sprague Dawley rats

Obesity aggravates neuroinflammatory and neurodegenerative effects of bisphenol A in female rats

Bisphenol A (BPA), a common plasticizer, is categorized as a neurotoxic compound. Its impact on individuals exhibits sex-linked variations. Several biological and environmental factors impact the degree of toxicity. Moreover, nutritional factors have profound influence on toxicity outcome. BPA has been demonstrated to be an obesogen. However, research on the potential role of obesity as a confounding factor in BPA toxicity is lacking. We studied the neurodegenerative effects in high-fat diet (HFD)-induced obese female rats after exposure to BPA (10 mg/L via drinking water for 90 days). Four groups were taken in this study - Control, HFD, HFD + BPA and BPA. Cognitive function was evaluated through novel object recognition (NOR) test. Inflammatory changes in brain, and changes in hormonal level, lipid profile, glucose tolerance, oxidative stress, and antioxidants were also determined. HFD + BPA group rats showed a significant decline in memory function in NOR test. The cerebral cortex (CC) of the brain showed increased neurodegenerative changes as measured by microtubule-associated protein-2 (MAP-2) accompanied by histopathological confirmation. The increased level of neuroinflammation was demonstrated by microglial activation (Iba-1) and protein expression of nuclear factor- kappa B (NF-КB) in the brain. Obesity also caused significant (p < 0.05) increase in lipid peroxidation accompanied by reduced activities of antioxidant enzymes (glutathione S-transferase, catalase and glutathione peroxidase) and decrease in reduced-glutathione (p < 0.05) when compared to non-obese rats with BPA treatment. Overall, study revealed that obesity serves as a risk factor in the toxicity of BPA which may exacerbate the progression of neurological diseases.

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.

Bisphenol A and its structural analogues exhibit differential potential to induce mitochondrial dysfunction and apoptosis in human granulosa cells

Bisphenol A (BPA) is an endocrine disruptor strongly associated with ovarian dysfunction. BPA is being substituted by structurally similar chemicals, such as bisphenol S (BPS), bisphenol F (BPF), and bisphenol AF (BPAF). However, the toxicity of these analogues in female reproduction remains largely unknown. This study evaluated the effects of BPA and its analogues BPS, BPF, and BPAF on the mitochondrial mass and function, oxidative stress, and their potential to induce apoptosis of human granulosa cells (KGN cells). BPA and its analogues, especially BPA and BPAF, significantly decreased mitochondrial activity and cell viability. The potential of bisphenols to reduce mitochondrial mass and function differed in the following order: BPAF > BPA > BPF > BPS. Flow cytometry revealed that exposure to bisphenols significantly increased mitochondrial ROS levels and increased mitochondrial Ca2+ levels. Thus, bisphenols exposure causes mitochondrial stress in KGN cells. At the same time, bisphenols exposure significantly induced apoptosis. These results thus emphasize the toxicity of these bisphenols to cells. Our study suggests the action mechanism of BPA and its analogues in damage caused to ovarian granulosa cells. Additionally, these novel analogues may be regrettable substitutes, and the biological effects and potential risks of BPA alternatives must be evaluated.

Perinatal bisphenol S exposure exacerbates the oxidative burden and apoptosis in neonatal ovaries by suppressing the mTOR/autophagy axis

Bisphenol S (BPS) is an emerging environmental endocrine disruptor capable of crossing the placental barrier, resulting in widespread exposure to pregnant women due to its extensive usage. However, the impact of perinatal maternal exposure to BPS on reproductive health in offspring and the underlying molecular mechanism remain underexplored. In this study, gestational ICR mice were provided with drinking water containing 3.33 mg/L BPS to mimic possible human exposure in some countries. Results demonstrated that BPS accelerated the breakdown of germ-cell cysts and the assembly of primordial follicles in neonates, leading to oocyte over-loss. Furthermore, the expression levels of folliculogenesis-related genes (Kit, Nobox, Gdf9, Sohlh2, Kitl, Bmp15, Lhx8, Figla, and Tgfb1) decreased, thus compromising oocyte quality and disrupting early folliculogenesis dynamics. BPS also disrupted other aspects of offspring reproduction, including advancing puberty onset, disrupting the estrus cycle, and impairing fertility. Further investigation found that BPS exposure inhibited the activities and expression levels of antioxidant-related enzymes in neonatal ovaries, leading to the substantial accumulation of MDA and ROS. The increased oxidative burden exacerbated the intracellular apoptotic signaling, manifested by increased expression levels of pro-apoptotic markers (Bax, Caspase 3, and Caspase 9) and decreased expression levels of anti-apoptotic marker (Bcl2). Concurrently, BPS inhibited autophagy by increasing p-mTOR/mTOR and decreasing p-ULK1/ULK1, subsequently down-regulating autophagy flux-related biomarkers (LC3b/LC3a and Beclin-1) and impeding the degradation of autophagy substrate p62. However, the imbalanced crosstalk between autophagy, apoptosis and oxidative stress homeostasis was restored after rapamycin treatment. Collectively, the findings demonstrated that BPS exposure induced reproductive disorders in offspring by perturbing the mTOR/autophagy axis, and such autophagic dysfunction exacerbated redox imbalance and promoted excessive apoptosis. These results provide novel mechanistic insights into the role of autophagy in mitigating BPS-induced intergenerational reproductive dysfunction.

Urinary concentrations of bisphenol A and its alternatives: Potential predictors of and associations with antral follicle count among women from an infertility clinic in Northern China

BACKGROUND

Experimental studies have suggested exposure to bisphenol A (BPA) and its alternatives, such as bisphenol F (BPF) and bisphenol S (BPS), may exert adverse effects on ovarian reserve, but human evidence is limited. Moreover, the potential predictors of exposure to bisphenols among women seeking infertility treatment have not been reported.

OBJECTIVE

To explore whether individual or mixture of BPA, BPF, and BPS were related to antral follicle count (AFC), and further identify the predictors of exposure to bisphenols among women seeking assisted reproductive treatment.

METHODS

A total of 111 women from a reproductive center in Shenyang, China were enrolled in this study from September 2020 to February 2021. The concentrations of urinary BPA, BPF, and BPS were measured using ultra-high-performance liquid chromatography-triple quadruple mass spectrometry (UHPLC-MS/MS). AFC was measured by two infertility physicians through transvaginal ultrasonography on the 2-5 days of a natural cycle. Demographic characteristics, dietary habits, and lifestyles were obtained by questionnaires. The associations between individual and mixture of urinary bisphenols concentrations (BPA, BPF, and BPS) and AFC were assessed by the Poisson regression models and the quantile-based g-computation (QGC) model, respectively. The potential predictors of exposure to bisphenols were identified by the multivariate linear regression models.

RESULTS

After adjusting for confounders, elevated urinary concentrations of BPA, BPF and BPS were associated with reduced AFC (β = -0.016; 95%CI: -0.025, -0.006 in BPA; β = -0.017; 95%CI: -0.029, -0.004 in BPF; β = -0.128; 95%CI: -0.197, -0.060 in BPS). A quantile increase in the bisphenols mixture was negatively associated with AFC (β = -0.101; 95%CI: -0.173, -0.030). Intake of fried food had higher urinary concentrations of BPF, BPS, and total bisphenols (∑BPs) than women who did not eat, and age was related to increased urinary BPF concentrations.

CONCLUSION

Our findings indicated that exposure to individual BPA, BPF, BPS and bisphenol mixtures were associated with impaired ovarian reserve. Furthermore, the intake of fried food, as identified in this study, could serve as an important bisphenols exposure route for reproductive-aged women.

A biochemical and histological evaluation of in vivo exposure of bisphenol P for multi-organ toxicity and pathology in rats

Bisphenol P (BPP) is a structural analog of bisphenol A (BPA) and is increasingly used as a substitute of BPA in commercial and household applications. In recent years, BPP has been frequently detected in terrestrial and aquatic ecosystems. Very little epidemiological and experimental information are available on the toxicity potential of BPP in human and animal systems, which is very concerning in view of its increasing use. The current study evaluated the biochemical and histopathological effects of BPP in rats. The seven experimental groups (n = 5 rats/group) included BPA5 (5 mg), BPA50 (50 mg), BPA100 (100 mg), BPP5 (5 mg), BPP50 (50 mg), and BPP100 (100 mg) while the remaining one group served as untreated control. At the end of treatment, the organs (liver, kidney, heart, and lung) of rats were harvested for oxidative stress and histopathological analyses. A significant (p < .05) decrease was observed in the weight of the liver, lungs, and kidneys in the BPP100 group similar to the BPA100 group compared with the control group. Further, a significant (p < .05) decrease was also observed for concentrations of antioxidant enzymes (catalase, peroxidase, superoxide dismutase, and glutathione peroxidase) in the liver, lungs, kidneys, and heart at the highest two doses of BPP similar to the respective BPA groups compared with the control group. The two highest doses of BPP induced histopathological changes in the liver such as nuclei distortion, excessive necrosis of hepatocytes, nuclei shrinkage and pyknosis of cells with disrupted cell structure (BPP100), and cellular congestion and degeneration of hepatocytes (BPP50) similar to the two respective doses of BPA. The BPP treated groups also showed varying histopathological changes in kidney tissue, heart tissue, and lung tissue similar to BPA treated rats. In conclusion, the present study indicated that BPP has the potential to induce oxidative stress and alter the histomorphological architecture of different organs and is as deleterious as BPA.

"Cocktail" of environmental chemicals and early reproductive outcomes of IVF: The insight from paternal and maternal exposure

BACKGROUND

Humans are exposed to various chemicals, including organophosphate esters (OPEs), phthalates (PAEs), and phenols. The effects on early reproductive outcomes of in vitro fertilization (IVF) remain unclear.

METHODS

We recruited 192 women and 157 men who underwent IVF treatment. A total of forty-nine urinary chemicals were detected, including six OPEs, fifteen PAEs, six parabens, two chlorophenols, nine bisphenols, five benzophenones, and six synthetic phenolic antioxidants. We examined the individual and joint effects of parental chemical exposure on early reproductive outcomes.

RESULTS

We found that certain chemicals were associated with early reproductive outcomes in Poisson regression models. For example, urinary diphenyl phosphate was negatively associated with high-quality embryos in both female (β: -0.12, 95%CI: -0.17, -0.07) and male partners (β: -0.09, 95%CI: -0.15, -0.03). A negative association was found between mixed chemicals and high-quality embryos in Bayesian kernel machine regression, weighted quantile sum regression (β: -0.34, 95%CI: -0.60, -0.07), and quantile-based g-computation model (β: -0.69, 95%CI: -1.34, -0.05) among female partners. Paternal mixture exposure was not associated with early reproductive outcomes.

CONCLUSIONS

Our results indicated that increased exposure to environmental chemicals was associated with adverse early reproductive outcomes of IVF, especially female partners.

Modulation of fetoplacental growth, development and reproductive function by endocrine disrupters

Maternal endocrine homeostasis is vital to a successful pregnancy, regulated by several hormones such as human chorionic gonadotropin, estrogen, leptin, glucocorticoid, insulin, prostaglandin, and others. Endocrine stress during pregnancy can modulate nutrient availability from mother to fetus, alter fetoplacental growth and reproductive functions. Endocrine disrupters such as bisphenols (BPs) and phthalates are exposed in our daily life's highest volume. Therefore, they are extensively scrutinized for their effects on metabolism, steroidogenesis, insulin signaling, and inflammation involving obesity, diabetes, and the reproductive system. BPs have their structural similarity to 17-β estradiol and their ability to bind as an agonist or antagonist to estrogen receptors to elicit an adverse response to the function of the endocrine and reproductive system. While adults can negate the adverse effects of these endocrine-disrupting chemicals (EDCs), fetuses do not equip themselves with enzymatic machinery to catabolize their conjugates. Therefore, EDC exposure makes the fetoplacental developmental window vulnerable to programming in utero. On the one hand prenatal BPs and phthalates exposure can impair the structure and function of the ovary and uterus, resulting in placental vascular defects, inappropriate placental expression of angiogenic growth factors due to altered hypothalamic response, expression of nutrient transporters, and epigenetic changes associated with maternal endocrine stress. On the other, their exposure during pregnancy can affect the offspring's metabolic, endocrine and reproductive functions by altering fetoplacental programming. This review highlights the latest development in maternal metabolic and endocrine modulations from exposure to estrogenic mimic chemicals on subcellular and transgenerational changes in placental development and its effects on fetal growth, size, and metabolic & reproductive functions.

The PCOS-NAFLD Multidisease Phenotype Occurred in Medaka Fish Four Generations after the Removal of Bisphenol A Exposure

As a heterogeneous reproductive disorder, polycystic ovary syndrome (PCOS) can be caused by genetic, diet, and environmental factors. Bisphenol A (BPA) can induce PCOS and nonalcoholic fatty liver disease (NAFLD) due to direct exposure; however, whether these phenotypes persist in future unexposed generations is not currently understood. In a previous study, we observed that transgenerational NAFLD persisted in female medaka for five generations (F4) after exposure to an environmentally relevant concentration (10 μg/L) of BPA. Here, we demonstrate PCOS in the same F4 generation female medaka that developed NAFLD. The ovaries contained immature follicles, restricted follicular progression, and degenerated follicles, which are characteristics of PCOS. Untargeted metabolomic analysis revealed 17 biomarkers in the ovary of BPA lineage fish, whereas transcriptomic analysis revealed 292 genes abnormally expressed, which were similar to human patients with PCOS. Metabolomic-transcriptomic joint pathway analysis revealed activation of the cancerous pathway, arginine-proline metabolism, insulin signaling, AMPK, and HOTAIR regulatory pathways, as well as upstream regulators esr1 and tgf signaling in the ovary. The present results suggest that ancestral BPA exposure can lead to PCOS phenotypes in the subsequent unexposed generations and warrant further investigations into potential health risks in future generations caused by initial exposure to EDCs.

Genetic background in the rat affects endocrine and metabolic outcomes of bisphenol F exposure

Environmental bisphenol compounds like bisphenol F (BPF) are endocrine-disrupting chemicals (EDCs) affecting adipose and classical endocrine systems. Genetic factors that influence EDC exposure outcomes are poorly understood and are unaccounted variables that may contribute to the large range of reported outcomes in the human population. We previously demonstrated that BPF exposure increased body growth and adiposity in male N/NIH heterogeneous stock (HS) rats, a genetically heterogeneous outbred population. We hypothesize that the founder strains of the HS rat exhibit EDC effects that were strain- and sex-dependent. Weanling littermate pairs of male and female ACI, BN, BUF, F344, M520, and WKY rats randomly received either vehicle (0.1% EtOH) or 1.125 mg BPF/l in 0.1% EtOH for 10 weeks in drinking water. Body weight and fluid intake were measured weekly, metabolic parameters were assessed, and blood and tissues were collected. BPF increased thyroid weight in ACI males, thymus and kidney weight in BUF females, adrenal weight in WKY males, and possibly increased pituitary weight in BN males. BUF females also developed a disruption in activity and metabolic rate with BPF exposure. These sex- and strain-specific exposure outcomes illustrate that HS rat founders possess diverse bisphenol-exposure risk alleles and suggest that BPF exposure may intensify inherent organ system dysfunction existing in the HS rat founders. We propose that the HS rat will be an invaluable model for dissecting gene EDC interactions on health.

Different types of bisphenols alter ovarian steroidogenesis: Special attention to BPA

Endocrine disruptors such as bisphenol A (BPA) and some of its analogues, including BPS, BPAF, and BPE, are used extensively in the manufacture of plastics. These synthetic chemicals could seriously alter the functionality of the female reproductive system. Although the number of studies conducted on other types of bisphenols is smaller than the number of studies on BPA, the purpose of this review study was to evaluate the effects of bisphenol compounds, particularly BPA, on hormone production and on genes involved in ovarian steroidogenesis in both in vitro (human and animal cell lines) and in vivo (animal models) studies. The current data show that exposure to bisphenol compounds has adverse effects on ovarian steroidogenesis. For example, BPA, BPS, and BPAF can alter the normal function of the hypothalamic-pituitary-gonadal (HPG) axis by targeting kisspeptin neurons involved in steroid feedback signals to gonadotropin-releasing hormone (GnRH) cells, resulting in abnormal production of LH and FSH. Exposure to BPA, BPS, BPF, and BPB had adverse effects on the release of some hormones, namely 17-β-estradiol (E2), progesterone (P4), and testosterone (T). BPA, BPE, BPS, BPF, and BPAF are also capable of negatively altering the transcription of a number of genes involved in ovarian steroidogenesis, such as the steroidogenic acute regulatory protein (StAR, involved in the transfer of cholesterol from the outer to the inner mitochondrial membrane, where the steroidogenesis process begins), cytochrome P450 family 17 subfamily A member 1 (Cyp17a1, which is involved in the biosynthesis of androgens such as testosterone), 3 beta-hydroxysteroid dehydrogenase enzyme (3β-HSD, involved in the biosynthesis of P4), and cytochrome P450 family 19 subfamily A member 1 (Cyp19a1, involved in the biosynthesis of E2). Exposure to BPA, BPB, BPF, and BPS at prenatal or prepubertal stages could decrease the number of antral follicles by activating apoptosis and autophagy pathways, resulting in decreased production of E2 and P4 by granulosa cells (GCs) and theca cells (TCs), respectively. BPA and BPS impair ovarian steroidogenesis by reducing the function of some important cell receptors such as estrogens (ERs, including ERα and ERβ), progesterone (PgR), the orphan estrogen receptor gamma (ERRγ), the androgen receptor (AR), the G protein-coupled estrogen receptor (GPER), the FSHR (follicle-stimulating hormone receptor), and the LHCGR (luteinizing hormone/choriogonadotropin receptor). In animal models, the effects of bisphenol compounds depend on the type of animals, their age, and the duration and dose of bisphenols, while in cell line studies the duration and doses of bisphenols are the matter.

Exploration of the damage and mechanisms of BPS exposure on the uterus and ovary of adult female mice

Bisphenol S (BPS) has been followed with interest for its endocrine disrupting effects, but exploration on the reproductive system of adult females is lack of deep investigation. In the present study, adult female CD-1 mice were treated with BPS for 28 days at 300 μg/kg/day. After that, uteruses and ovaries were harvested for histopathological examination, RNA-seq analysis, and diseases risk prediction. Hematoxylin-eosin (H&E) staining results showed significant histological alterations in the uterus and ovary of the BPS-exposed mice. Bioinformatics analysis of the RNA-seq screened a certain number of differentially expressed genes (DEGs) in both uterus and ovary between BPS group and their corresponding vehicle control groups (Veh), respectively. Functional enrichment analysis of DEGs found that hormone metabolism and immunoinflammatory related pathways were enriched. Disease risk evaluation of the hub genes was performed and the results indicated that diseases associated with uterus and ovary were mainly related to tumors and cancers. Further pan cancer and ovarian cancer survival analysis based on human diseases database pointed out, Foxa1, Gata3, S100a8 and Shh for uterus, Itgam, Dhcr7, Fdps, Hmgcr, Hsd11b1, Hsd3b1, Ptges, F3, Fn1, Ptger4 and Srd5a1 for ovary were significant correlation with cancer. The findings suggest that BPS causes some histopathological changes, alters the expressions of hub genes, enhances uterine and ovarian tumors or even cancer risks.

Bisphenol-S Influence on Oxidative Stress and Endocrine Biomarkers of Reproductive System: A Systematic Review and Meta-Analysis

Background

Bisphenol-S (BPS), as a new human public health concern, was introduced to the plastic industry by BPA-free labeled products following the restrictions of Bisphenol-A (BPA) as a safe alternative. However, recent research has revealed a controversial issue. In this regard, the present study aimed to review the relationship between BPS exposure and reproductive system dis/malfunction.

Methods

PubMed and other databases were searched up to January 2021. The standard mean difference (SMD) with a 95% confidence interval (CI) was calculated for the main parameters using the random-effects model. Finally, 12 studies with 420 subjects were included in this research. Forest plot, meta-regression, and non-linear dose-response effect were calculated for each parameter by random-effects model.

Results

Based on the results of in vitro assessment, a significant increase was found in the oxidative stress parameters, including superoxide dismutase (SMD: 0.63, 95% CI: 0.321, 0.939), thiobarbituric acid reactive substances (SMD: 0.760, 95% CI: 0.423, 1.096), and reactive oxygen species (SMD: 0.484, 95% CI: 0.132, 0.835). In addition, the hormonal assessment revealed a significant decrease in male testosterone concertation (SMD: -0.476, 95% CI: -0.881, -0.071). Moreover, in vivo examination revealed a significant decrease in hormonal parameters, such as female testosterone (SMD: -0.808, 95% CI: -1.149, -0.467), female estrogen (SMD: -2.608, 95% CI: -4.588, -0.628), female luteinizing hormone (SMD: -0.386, 95% CI: -0.682, -0.089), and female follicle-stimulating hormone (FSH) (SMD: -0.418, 95% CI: -0.716, -0.119). Besides, linear and non-linear correlations were detected in the main parameters.

Conclusion

In conclusion, based on the current meta-analysis, BPS was suggested to be toxic for the reproductive system, similar to the other bisphenols. Moreover, a possible correlation was indicated between oxidative and hormonal status disruption induced by BPS in male and female reproductive systems dis/malfunction.

Effects of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) on reproductive and endocrine function in female zebrafish (Danio rerio)

BACKGROUND

Polybrominated diphenyl ethers (PBDEs), a group of brominated flame retardants (BFRs), were reported exist extensively in various ecological environmental. Studies have indicated that PBDEs induce reproductive toxic effects on human health, but the mechanisms remain poorly understood. In this study, the adult female zebrafish were used to investigate the effects of 2, 2', 4, 4'-tetrabromodiphenyl ether (BDE-47) on the reproductive endocrine system and its mechanism.

METHODS

Female zebrafish (AB strains) were continuously exposed to BDE-47 at the concentrations of 0, 10, 50, 100 and 500 µg/L till 21 days. The morphology of ovary were stained and evaluated with hematoxylin-eosin (H&E), and levels of sex hormones including follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone (T) and 17β-estradiol (E₂) and the biomarkers of oxidative stress such as superoxide dismutase (SOD) and malondialdehyde (MDA), were measured via ELISA. Subsequently, the expression of genes along the hypothalamic pituitary-gonad (HPG) and oxidative stress were determined using quantitative real-time PCR (qRT-PCR).

RESULT

The results showed that exposure to high level of BDE-47 reduced the index of condition factor (CF) and gonadosomatic index (GSI). Treatment with BDE-47 impaired the normal development and structure of oocytes in zebrafish ovary. Moreover, the steroid hormone of FSH, LH, T and E₂ were significantly decreased in BDE-47 exposure group. A dose-dependent elevation in SOD activity and MDA levels were recorded. Meanwhile, the transcription level of cyp19a, cyp19b, fshβ, lhβ were up-regulated while the transcription of fshr, lhr, cyp17a, 17βhsd were down-regulated in the gonad of female adult zebrafish.

CONCLUSION

Exposure to BDE-47 have detrimental impact on the development of ovary, decreasing sex hormone levels, inducing oxidative damage as well as altering HPG axis-related genes.

A holistic assessment of the sources, prevalence, and distribution of bisphenol A and analogues in water, sediments, biota and plastic litter of the Ebro Delta (Spain)

Bisphenol A (BPA) is one of the main ubiquitous compounds released from plastics in the environment. This compound, considered an endocrine disruptor, poses a risk to aquatic wildlife and human population, being included in multiple environmental monitoring programmes. Following the regulations restricting BPA use in the last years, BPA-like chemicals have been produced and used as BPA substitutes. However, they are not commonly included in monitoring programs yet and their presence is thus misrepresented, despite showing similar endocrine disrupting potential. In this work, an analytical method for analysing bisphenol A and five of its analogues (Bisphenol S, B, F, AF and Tetrabromobisphenol A) is described, validated for water (riverine, sea and wastewater), sediment, and biota (fish and biofilm) and applied to monitor their presence in the Ebro River Delta (NE Spain). In addition, plastic litter was also collected to evaluate their role as potential source of bisphenols. All compounds except BPF were detected in the analysed samples. Wastewater treatment plants (WWTPs) were discarded as major sources of BPs into the natural aquatic environment, as no BPs were detected in treated effluents. Indeed, the high levels of BPs in the natural environment could be related with direct discharge of raw wastewater from small rural population nucleus. The analysis of riverine plastic leachates yielded 4 out of the 6 BPs analysed, strengthening the hypothesis that plastic debris are also a source of BPs in the natural environment. Whereas Bisphenol S and BPA were detected in water and, to a limited extent, in biota, less polar analogues (mainly BPAF and TBBPA) were not found in any of the water samples. Instead, these hydrophobic BPs were found in fish tissues and biofilm, pointing out plastics and microplastics as their possible vectors. Finally, biofilm demonstrated its potential as sentinel of chemical contamination in freshwater environment.

The effects of endocrine-disrupting chemicals on ovarian- and ovulation-related fertility outcomes

Exposure to endocrine-disrupting chemicals (EDCs) is unavoidable, which represents a public health concern given the ability of EDCs to target the ovary. However, there is a large gap in the knowledge about the impact of EDCs on ovarian function, including the process of ovulation. Defects in ovulation are the leading cause of infertility in women, and EDC exposures are contributing to the prevalence of infertility. Thus, investigating the effects of EDCs on the ovary and ovulation is an emerging area for research and is the focus of this review. The effects of EDCs on gametogenesis, uterine function, embryonic development, and other aspects of fertility are not addressed to focus on ovarian- and ovulation-related fertility issues. Herein, findings from epidemiological and basic science studies are summarized for several EDCs, including phthalates, bisphenols, per- and poly-fluoroalkyl substances, flame retardants, parabens, and triclosan. Epidemiological literature suggests that exposure is associated with impaired fecundity and in vitro fertilization outcomes (decreased egg yield, pregnancies, and births), while basic science literature reports altered ovarian follicle and corpora lutea numbers, altered hormone levels, and impaired ovulatory processes. Future directions include identification of the mechanisms by which EDCs disrupt ovulation leading to infertility, especially in women.

Bisphenol S Impairs Oestradiol Secretion during In Vitro Basal Folliculogenesis in a Mono-Ovulatory Species Model

Bisphenol S (BPS) affects terminal folliculogenesis by impairing steroidogenesis in granulosa cells from different species. Nevertheless, limited data are available on its effects during basal folliculogenesis. In this study, we evaluate in vitro the effects of a long-term BPS exposure on a model of basal follicular development in a mono-ovulatory species. We cultured ovine preantral follicles (180−240 μm, n = 168) with BPS (0.1 μM (possible human exposure dose) or 10 μM (high dose)) and monitored antrum appearance and follicular survival and growth for 15 days. We measured hormonal secretions (oestradiol (at day 13 [D13]), progesterone and anti-Müllerian hormone [D15]) and expression of key follicular development and redox status genes (D15) in medium and whole follicles, respectively. BPS (0.1 µM) decreased oestradiol secretion compared with the control (−48.8%, p < 0.001), without significantly impairing antrum appearance, follicular survival and growth, anti-Müllerian hormone and progesterone secretion and target gene expression. Thus, BPS could also impair oestradiol secretion during basal folliculogenesis as it is the case during terminal folliculogenesis. It questions the use of BPS as a safe BPA substitute in the human environment. More studies are required to elucidate mechanisms of action of BPS and its effects throughout basal follicular development.

Effects of Bisphenol A and Bisphenol F on Porcine Uterus Contractility

Introduction

Bisphenols, as endocrine disruptors, may cause a wide range of health problems in humans, but so far, not all of them have been confirmed in animals, including pigs. Since animals are also exposed to bisphenols, we hypothesised that these substances may have an effect on uterine contractility in pigs. Therefore, the aim of the study was to investigate the effect of the most-used bisphenol, bisphenol A (BPA), and a selected analogue, bisphenol F (BPF), on the contractile activity of the pig uterus.

Material and Methods

The investigation utilised smooth muscles from immature pigs (n = 6), cyclic pigs on days 12–14 of the oestrous cycle (n = 6) or early pregnant pigs on days 12–16 of pregnancy (n = 6). Strips of the myometrium were exposed to BPA and BPF at concentrations of 10⁻¹³–10⁻¹ M. Smooth muscle contractility was determined with equipment for measuring isometric contractions.

Results

BPA caused a significant decrease in contraction amplitude, and frequency and in myometrial tension in all groups examined. BPF caused a decrease in the amplitude and frequency of contractions in all groups and in myometrial tension in the early pregnant group.

Conclusion

The obtained results indicate that both BPA and BPF relaxed the porcine myometrium, but these changes, especially in the amplitude and frequency of contractions, were more evident after BPF treatment. The extent of relaxation is dependent on the physiological status of the animals.

Review on bisphenol A and the risk of polycystic ovarian syndrome: an insight from endocrine and gene expression

Bisphenol A (BPA) is one of the most widely studied endocrine disrupting chemicals because of its structural similarity to 17-β estradiol; its ability to bind as an agonist/antagonist to estrogen receptors elicits adverse effects on the functioning of the metabolic and endocrinal system. Therefore, BPA has been thoroughly scrutinized concerning its disruption of pathways like lipid metabolism, steroidogenesis, insulin signaling, and inflammation. This has resulted in reports of its correlation with various aspects of cardiovascular diseases, obesity, diabetes, male and female reproductive disorders, and dysfunctions. Among these, the occurrence of the polycystic ovarian syndrome (PCOS) in premenopausal women is of great concern. PCOS is a highly prevalent disorder affecting women in their reproductive age and is clinically characterized by hyperandrogenism, ovulatory dysfunction, and polycystic ovarian morphology, along with metabolism-related dysfunctions like hyperinsulinemia, obesity, and insulin resistance. In this review, we analyzed certain researched effects of BPA, while focusing on its ability to alter the expression of various significant genes like GnRH, AdipoQ, ESR1, StAR, CYP11A1, CYP19A1, and many more involved in the pathways and endocrine regulation, whose disruption is commonly associated with the clinical manifestations of PCOS.

Pharmacokinetics and toxicity evaluation following oral exposure to bisphenol F

Bisphenol F is a substitute material for bisphenol A and is widely used in household products as a raw material for polycarbonate resin, epoxy resin, and plastic reinforcement. It is known to be mainly used in food containers, thermal paper for receipts, and coatings for water pipes. In some countries, bisphenol F has been detected in drinking water and human urine samples. However, due to the lack of safety evaluation data on bisphenol F, it is difficult to establish appropriate guidelines for the proper use of the substance, and social anxiety is increasing accordingly. This study investigated the use, exposure route, and distribution flow of bisphenol F, a household chemical. To determine the no-observed-adverse-effect level (NOAEL) and target organ of bisphenol F after exposure, a single-dose oral toxicity, dose-range finding (28 day oral), repeated dose toxicity (90 day oral), and genotoxicity (reverse mutation, chromosomal abnormality, in vivo micronucleus test) tests were performed. The pharmacokinetic profile was also obtained. The test results are as follows: in the pharmacokinetic study, it was confirmed that single oral exposure to BPF resulted in systemic exposure; in single oral dose toxicity test, the approximate lethal dose was found to be 4000 mg/kg and confusion and convulsion was shown in the test animals; NOAEL was determined to be 2 mg/kg/day for male and 5 mg/kg/day for female, and the no-observed-effect level (NOEL) was determined to be 2 mg/kg/day for males and 1 mg/kg/day for females, and the target organ was the small intestine; genotoxicity tests confirmed that BPF does not induce genotoxicity.

The Effects of Prenatal and Lactational Bisphenol A and/or Di(2-Ethylhexyl) Phthalate Exposure on Female Reproductive System

Bisphenol A (BPA) and di(2-ethylhexyl) phthalate (DEHP) are endocrine disrupting chemicals (EDCs) which are abundantly used in polyvinyl chloride plastics, polycarbonates and epoxy resins. Prenatal and early postnatal exposures to EDCs are suggested to be more critical. Such exposures can lead to reprotoxic effects, hormonal and metabolic consequences in adulthood. Moreover, combined exposure to different EDCs can lead to more serious adverse effects, some of which cannot be predicted by examining their individual toxicity profiles. This study aimed to evaluate effects of single and combined prenatal and lactational exposures to BPA and/or DEHP on female reproductive hormones and ovarian follicle development. Pregnant Sprague-Dawley rats were divided randomly to four groups (n = 3/group): Control (received vehicle only); DEHP (30 mg/kg/day); BPA (50 mg/kg/day) and BPA + DEHP (30 mg/kg/day DEHP; 50 mg/kg/day BPA) through 6-21 gestational days and lactation by intra-gastric lavage. Female offspring (n = 6/group) were fed until the end of twelfth postnatal week and then euthanized. Reproductive hormones, ovarian follicle numbers and ovarian development were determined. Plasma testosterone and estradiol levels of BPA and BPA + DEHP groups were significantly lower than control. In BPA group, the number of tertiary ovarian follicles decreased significantly compared to control. In the combined exposure group, the number of corpus luteum (29%) as well as the number of primordial follicles (36%) showed marked decreases compared to control group.It can be suggested that early life exposure to BPA and DEHP may cause late life adverse effects in female reproductive system especially after combined exposure.

New bisphenol A and bisphenol S analogs: Evaluation of their hERα agonistic and antagonistic activities using the OECD 455 in-vitro assay and molecular modeling

Bisphenol A (BPA) and bisphenol S (BPS) are agonists of hERα receptors and due to BPA regulations in many countries, several substitutes that are close analogs to BPA and BPS were developed. In the presented study, we have determined human estrogen receptor (hER)α agonist and antagonist activities with the validated OECD assay with the hERα-Hela9903 cell line for five different chemical classes of BPA and BPS analogs. This study also defined clear structure-activity relationships for agonist and antagonist activities of the 12 bisphenols on hERα, which are supported by molecular docking studies. These data show that classical analogs of BPA (e.g., bisphenols B, C, AP, E) have comparable or superior estrogenic agonist potencies compared to BPA and BPS. The most potent of these hERα agonists were even more potent than BPA, as bisphenol B and C, with IC50 values of 0.31 μM and 0.48 μM, respectively. Among these selected bisphenols, 4-4'-methylenebis (oxyethylenethio)diphenol was the most potent hERα antagonist, with an IC50 of 0.39 μM. The estrogenic agonist and antagonist potencies of these different chemical classes of BPA and BPS analogs are mutually comparable and can be used as a basis for further structure-activity relationships studies and human risk assessment.

Profile of Environmental Chemicals in the Korean Population-Results of the Korean National Environmental Health Survey (KoNEHS) Cycle 3, 2015-2017

The Korean National Environmental Health Survey (KoNEHS) program provides useful information on chemical exposure, serves as the basis for environmental health policies, and suggests appropriate measures to protect public health. Initiated on a three-year cycle in 2009, it reports the concentrations of major environmental chemicals among the representative Korean population. KoNEHS Cycle 3 introduced children and adolescents into the analysis, where the blood and urine samples of 6167 participants were measured for major metals, phthalates, phenolics, and other organic compounds. Lead, mercury, cadmium, metabolites of DEHP and DnBP, and 3-phenoxybenzoic acid levels of the Korean adult population tended to decrease compared to previous survey cycles but remained higher than those observed in the US or Canada. Both bisphenol A (BPA) and trans,trans-muconic acid concentrations have increased over time. Heavy metal concentrations (blood lead, and cadmium) in children and adolescents were approximately half that of adults, while some organic substances (e.g., phthalates and BPA) were high. BPA showed higher levels than in the US or Canada, whereas BPF and BPS showed lower detection rates in this cycle; however, as these are increasingly used as a substitute for BPA, further research is necessary. As environmental chemicals may affect childhood health and development, additional analyses should assess exposure sources and routes through continuous observations.

Evaluation of curcuma and ginger mixture ability to prevent ROS production induced by bisphenol S: an in vitro study

The use of bisphenol S (BPS) as a substitute of Bisphenol A is increasing in several products and it can be found in different environmental and biological matrices. Its toxicity has been studied at different levels and one of BPS toxic mechanisms at high concentrations seems to be the induction of oxidative stress through the generation of reactive oxygen species (ROS). This study evaluates the ability of a curcuma and ginger (CG) mixture to exert an antioxidant effect on rat hepatocytes treated with BPS. The effects of the mixture were compared to those of a well-known antioxidant (Trolox). Three different BPS concentrations were used in order to verify ROS production. 70 µg/mL and 150 µg/mL of BPS generated a significant ROS increase (p < 0.01) as compared to control, while CG mixture was able to decrease this ROS production in hepatic cells, as compared to cells treated with 70 µg/ml of BPS (p < 0.01) restoring control levels. BPS 70 µg/mL was tested for total antioxidant capacity (TEAC), superoxide dismutase (SOD) and total thiols. TEAC and SOD significant decreased (p < 0.05 and p < 0.01, respectively) as compared to controls and CG mixture was able to restore control values. Given the widespread BPS use, results obtained in this study can be of high impact for the community, demonstrating the ability of a mixture of natural products to prevent BPS-induced oxidative stress.

The association between bisphenol A exposure and oxidative damage in rats/mice: A systematic review and meta-analysis

Numerous studies reported that BPA could cause oxidative damage to different tissues in rats/mice. This study aimed to perform a systematic review and meta-analysis of BPA exposure on oxidative damage in rats/mice. A comprehensive literature search was conducted using PubMed, Embase, and Web of Science databases from their inception date until July 18, 2020. 20 eligible articles were included in this study. The results showed that BPA could significantly increase the level of MDA (SMD, 16.88; 95%CI, 12.06-21.71), but there was a significant reduction in the contents of antioxidants, such as GR (-10.46, -13.91 ∼ -7.02), CAT (-8.48, -11.66 ∼ -5.30), GPx (-9.37, -11.95 ∼ -6.80), GST (-7.59, -14.51 ∼ -0.67), GSH (-10.64, -13.96 ~ -7.33), and SOD (-6.48, -8.37 ∼ -4.58) in rats/mice. Our study provided clear evidence that BPA exposure could significantly induce oxidative damage in rats/mice. And we also found that the degree of oxidative damage was related to BPA dose, target tissue, intervention means, and exposure duration of BPA.

Internal exposure of Chinese children from a typical coastal city to bisphenols and possible association with thyroid hormone levels

Bisphenols (BPs) are widely used in consumer products, and human exposure to BPs is nearly ubiquitous. However, human biomonitoring data are scarce, especially for children. In this study, we quantified eight BPs in the serum of 345 children from a typical coastal city in China. Bisphenol A (BPA), bisphenol F (BPF), and bisphenol S (BPS) were frequently detected (63% BPA, 68% BPF, 43% BPS), with geometric mean (GM) concentrations of 1.6, 0.08, and 0.04 ng/mL, respectively. The other five BPs had low detection frequencies (<5%). The distribution of BPA, BPF, and BPS in children's serum samples was independent of sex whereas the concentrations of BPS and BPF both significantly increased with age (P < 0.01). The GM values of estimated daily intake for BPA and BPS were 0.61 and 0.014 μg/kg body weight (bw)/day, respectively, indicating a relatively higher exposure risk of BPA in comparison with BPS. Compared with the population with euthyroid or nonhyperthyroid thyroid dysfunction, children with hyperthyroidism suffered higher exposure to BPA. By multiple linear regression analysis, thyroid-stimulating hormone showed a significantly negative relationship with log₁₀-BPA concentration for euthyroid children (R² = 0.477, P < 0.001), whereas a significantly positive correlation (R² = 0.753, P = 0.033) was found for hyperthyroid children.

Bisphenol analogs AF and S: Effects on cell status and production of angiogenesis-related factors by COV434 human granulosa cell line

While Bisphenol A (BPA) has been a requisite plastic additive, as an endocrine disruptor it has been associated with adverse health effects including ovarian disorders. Following implemented restrictions on BPA usage, it is replaced by alternative bisphenols, biological effects of which have not been adequately investigated. Our study examined effects of bisphenols AF (BPAF) and S (BPS), on the human ovarian granulosa cell line COV434, and compared them with BPA, with the focus on cell viability (10^-9-10^-4 M) and angiogenesis-related factors (10^-9-10^-5 M), relevant for both the follicle development and ovarian pathologies: vascular endothelial growth factor A (VEGF-A), platelet-derived growth factor AA (PDGF-AA), and matrix metalloproteinase 9 (MMP-9). Each bisphenol impaired cell viability and increased generation of intracellular reactive oxygen species at the highest concentration (10^-4 M). While VEGF-A production in BPAF-treated groups did not differ from the control, all doses of BPS and BPA caused a marked reduction in VEGF-A output. Nevertheless, the alterations in VEGF-A production were not caused by the impact on VEGFA gene expression since there were no indications of VEGFA downregulation in the presence of either BPS or BPA. Interestingly, we observed a similar pattern of PDGF-AA output reduction in BPS- and BPA-treated groups to that of VEGF-A production. BPAF and BPS (10^-5 M) increased MMP9 expression, however, this effect was not reflected by the increase in MMP-9 production. The results obtained demonstrate that the novel bisphenol analogs are not inert with respect to the ovarian cells, and their effects might contribute to dysregulation of granulosa cells functions.

Bisphenol S is present in culture media used for ART and cell culture

STUDY QUESTION

Do plastic laboratory consumables and cell culture media used in ART contain bisphenols?

SUMMARY ANSWER

The majority of human embryo culture media assessed contained bisphenol S close to the nanomolar concentration range, while no release of bisphenols by plastic consumables was detected under routine conditions.

WHAT IS KNOWN ALREADY

The deleterious effect of the endocrine disruptor bisphenol A (BPA) on female fertility raised concerns regarding ART outcome. BPA was detected neither in media nor in the majority of plastic consumables used in ART; however, it might have already been replaced by its structural analogs, including bisphenol S (BPS).

STUDY DESIGN, SIZE, DURATION

Seventeen plastic consumables and 18 cell culture and ART media were assessed for the presence of bisphenols.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Ten different bisphenols (bisphenol A, S, AF, AP, B, C, E, F, P and Z) were measured using an isotopic dilution according to an on-line solid phase extraction/liquid chromatography/mass spectrometry method.

MAIN RESULTS AND THE ROLE OF CHANCE

While the plastic consumables did not release bisphenols under routine conditions, 16 of the 18 cell culture and ART media assessed contained BPS. Six media exhibited BPS concentrations higher than 1 nM and reached up to 6.7 nM (1693 ng/l).

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Further studies are required to investigate a greater number of ART media to identify less potentially harmful ones, in terms of bisphenol content.

WIDER IMPLICATIONS OF THE FINDINGS

As BPS has already been reported to impair oocyte quality at nanomolar concentrations, its presence in ART media, at a similar concentration range, could contribute to a decrease in the ART success rate. Thus far, there has been no regulation of these compounds in the ART context.

STUDY FUNDING/COMPETING INTERESTS

This study was financially supported by the ‘Centre-Val de Loire’ Region (Bemol project, APR IR 2017), INRAE, BRGM, the French National Research Agency (project ANR-18-CE34-0011-01 MAMBO) and the BioMedicine Agency (Project 18AMP006 FertiPhenol). The authors declare that they have no conflict of interest that could be perceived as prejudicing the impartiality of the reported research.

Bisphenol F Exposure in Adolescent Heterogeneous Stock Rats Affects Growth and Adiposity

Bisphenol F (BPF) is increasingly substituting bisphenol A in manufacturing polycarbonates and consumer products. The cardiometabolic effects of BPF in either humans or model organisms are not clear, and no studies to date have investigated the role of genetic background on susceptibility to BPF-induced cardiometabolic traits. The primary goal of this project was to determine if BPF exposure influences growth and adiposity in male N:NIH heterogeneous stock (HS) rats, a genetically heterogeneous population. Littermate pairs of male HS rats were randomly exposed to either vehicle (0.1% ethanol) or 1.125 µg/ml BPF in 0.1% ethanol for 5 weeks in drinking water starting at 3 weeks-of-age. Water consumption and body weight was measured weekly, body composition was determined using nuclear magnetic resonance, urine and feces were collected in metabolic cages, and blood and tissues were collected at the end of the study. BPF-exposed rats showed significantly increased body growth and abdominal adiposity, risk factors for cardiometabolic disease. Urine output was increased in BPF-exposed rats, driving a trend in increased creatinine clearance. We also report the first relationship between a bisphenol metabolizing enzyme and a bisphenol-induced phenotype. Preliminary heritability estimates of significant phenotypes suggest that BPF exposure may alter trait variation. These findings support BPF exposure as a cardiometabolic disease risk factor and indicate that the HS rat will be a useful model for dissecting gene by BPF interactions on metabolic health.

Elucidation of the Effects of Bisphenol A and Structural Analogs on Germ and Steroidogenic Cells Using Single Cell High-Content Imaging

Concerns about the potential adverse effects of bisphenol A (BPA) have led to an increase in the use of replacements, yet the toxicity data for several of these chemicals are limited. Using high-content imaging, we compared the effects of BPA, BPAF, BPF, BPS, BPM, and BPTMC in germ (C18-4 spermatogonial) and steroidogenic (MA-10 Leydig and KGN granulosa) cell lines. Effects on cell viability and phenotypic markers were analyzed to determine benchmark concentrations (BMCs) and estimate administered equivalent doses (AEDs). In all 3 cell lines, BPA was one of the least cytotoxic bisphenol compounds tested, whereas BPM and BPTMC were the most cytotoxic. Interestingly, BPF and BPS were cytotoxic only in MA-10 cells. Effects on phenotypic parameters, including mitochondria, lysosomes, lipid droplets, and oxidative stress, were both bisphenol- and cell-line specific. BPA exposure affected mitochondria (BMC: 1.2 μM; AED: 0.09 mg/kg/day) in C18-4 cells. Lysosome numbers were increased in MA-10 cells exposed to BPA or BPAF but decreased in KGN cells exposed to BPAF or BPM. Lipid droplets were decreased in C18-4 cells exposed to BPF and in MA-10 cells exposed to BPTMC but increased in BPF, BPM, and BPTMC-exposed KGN cells. BPA and BPM exposure induced oxidative stress in MA-10 and KGN cells, respectively. In summary, structurally similar bisphenols displayed clear cell-line-specific differences in BMC and AED values for effects on cell viability and phenotypic endpoints. This approach, together with additional data on human exposure, may aid in the selection and prioritization of responsible replacements for BPA. .

The comparative toxicities of BPA, BPB, BPS, BPF, and BPAF on the reproductive neuroendocrine system of zebrafish embryos and its mechanisms

Bisphenol A (BPA) is a well-known endocrine disruptor that has elicited great concern because of its potential toxic effects in organisms. In this study, the effects of BPA and several BPA structural analogs, including BPB, BPS, BPF, and BPAF, on the reproductive neuroendocrine system were evaluated during zebrafish embryonic and larval development. Our results showed that the numbers of gonadotropin-releasing hormone 3 neurons in zebrafish embryos increased after 100 μg/L BPA analog treatment, and exposure to BPA or its analogs at 1 or 100 μg/L increased the expression of reproductive neuroendocrine-related genes and the levels of typical hormones such as LH, FSH, E2, and GH. Moreover, the effects were associated with increases in the activities of erα, erβ, and cyp19a genes. The respective estrogen receptors (ER) and aromatase (AROM) antagonists significantly attenuated the stimulation of lhβ, fshβ, LH, and FSH expression, thereby proving that BPA analogs affect the reproductive neuroendocrine system via ERs and AROM pathway. Furthermore, we observed that the reproductive neuroendocrine toxicity of BPAF was more similar to that of BPA. This was the first study to comparatively explore the reproductive neuroendocrine toxicities of bisphenols in aquatic organism.

Comparative acute toxicity of benzophenone derivatives and bisphenol analogues in the Asian clam Corbicula fluminea

Among UV-filters, benzophenones are one of the most abundantly used and detected groups in the environment. Bisphenols are also one of the most widely used chemicals in plastics, but their demonstrated deleterious effects on several organisms and humans have led to the production of alternative analogues. However, few comparative studies on the ecotoxicological effects of these derivatives or analogues have been carried out. The present study aimed to investigate the effects of two benzophenones (BP-3 and BP-4) and two bisphenols (BPA and BPS) in a short-term exposure of the freshwater endobenthic bivalve Corbicula fluminea. Clams were exposed for 96 h to several concentrations of the four pollutants: BP-3 (0.63; 1.25; 2.5; 5 mg l^-1), BP-4 (4.75; 9.5; 19; 38 mg l^-1), BPA (3.75; 7.5; 15; 30 mg l^-1), and BPS (2.5; 5; 10; 20 mg l^-1). The comparative acute toxicity of these pollutants was evaluated by the analysis of the post-exposure filtering capacity of clams, lipid peroxidation (LP) levels and the activity of the antioxidant enzymes catalase (CAT) and glutathione reductase (GR). After the exposure period, except for BP-4, the chemicals tested seemed to be detected by clams and provoked valve closure, decreasing filter-feeding in a concentration-dependent manner. Furthermore, C. fluminea exposed to the highest concentrations of BP-3, BP-4 and BPA showed a significant increase in LP, CAT and GR activities with respect to their controls. BP-3 and BPA were the most toxic compounds showing significant differences in all the parameters analysed at the highest concentrations assayed. However, clams exposed to BPS showed only significant alterations in filtration parameters and in GR activity, in the two highest concentrations tested, indicating that this compound was the least toxic to clams. Obtained results highlight the importance of investigating the effects that emerging pollutants have on aquatic organisms.

Chronic exposure to bisphenol S induces oxidative stress, abnormal anxiety, and fear responses in adult zebrafish (Danio rerio)

Bisphenol S (BPS) is increasingly used in a wide range of industrial and consumer products, resulting in its ubiquitous distribution across the environment, including aquatic ecosystems. Although it is commonly known as a weak/moderate estrogenic compound, there has been a growing acknowledgment of the potential of BPS to cause toxicity by inducing oxidative stress. Oxidative stress is a major participant in the development of anxiety-like behaviors in humans and animals. Therefore, the present study was designed to examine the impact of BPS on anxiety-like behavior and fear responses in adult zebrafish and also to elucidate the possible linkage between the BPS neurotoxicity and oxidative status of the brain. To this end, adult male and female zebrafish were exposed to 0 (control), 1, 10, and 30 μg/L of BPS and 1 μg/L of 17-β-estradiol (E2) for 75 days. Following exposure, changes in anxiety and fear-related responses were evaluated by applying a novel tank test and by exposing focal fish to chemical alarm cues. Additionally, we evaluated the expression of multiple antioxidant genes in the zebrafish brain. Our results indicate that BPS, irrespective of exposure concentration, and E2 significantly decreased bottom-dwelling behavior and the latency to enter the upper water column. Furthermore, exposure to the highest concentration of BPS and E2 induced a significant decrease in fear-related responses. The impaired anxiety and reduced fear-related responses were associated with a down-regulation in the transcription of genes involved in enzymatic antioxidant defense. Taken together, our results suggest that chronic exposure to BPS impairs anxiety and fear responses in adult zebrafish, possibly by inducing oxidative stress in the brain.

Bisphenol B Exposure Disrupts Mouse Oocyte Meiotic Maturation in vitro Through Affecting Spindle Assembly and Chromosome Alignment

Bisphenol B (BPB), a substitute of bisphenol A (BPA), is widely used in the polycarbonate plastic and resins production. However, BPB proved to be not a safe alternative to BPA, and as an endocrine disruptor, it can harm the health of humans and animals. In the present study, we explored the effects of BPB on mouse oocyte meiotic maturation in vitro. We found that 150 μM of BPB significantly compromised the first polar body extrusion (PBE) and disrupted the cell cycle progression with meiotic arrest. The spindle assembly and chromosome alignment were disordered after BPB exposure, which was further demonstrated by the aberrant localization of p-MAPK. Also, BPB exposure increased the acetylation levels of α-tubulin. As a result, the spindle assemble checkpoint (SAC) was continuously provoked, contributing to meiotic arrest. We further demonstrated that BPB severely induced DNA damage, but the ROS and ATP production were not altered. Furthermore, the epigenetic modifications were changed after BPB exposure, as indicated by increased K3K9me3 and H3K27me3 levels. Besides, the pattern of estrogen receptor α (ERα) dynamics was disrupted with a mass gathering on the spindle in BPB-exposed oocytes. Our collective results indicated that exposure to BPB compromised meiotic maturation and damaged oocyte quality by affecting spindle assembly and chromosome alignment, acetylation of α-tubulin, DNA damage, epigenetic modifications, and ERα dynamics in mouse oocytes.

A comprehensive review of the neurobehavioral effects of bisphenol S and the mechanisms of action: New insights from in vitro and in vivo models

The normal brain development and function are delicately driven by an ever-changing milieu of steroid hormones arising from fetal, placental, and maternal origins. This reliance on the neuroendocrine system sets the stage for the exquisite sensitivity of the central nervous system to the adverse effects of endocrine-disrupting chemicals (EDCs). Bisphenol A (BPA) is one of the most common EDCs which has been a particular focus of environmental concern for decades due to its widespread nature and formidable threat to human and animal health. The heightened regulatory actions and the scientific and public concern over the adverse health effects of BPA have led to its replacement with a suite of structurally similar but less known alternative chemicals. Bisphenol S (BPS) is the main substitute for BPA that is increasingly being used in a wide array of consumer and industrial products. Although it was considered to be a safe BPA alternative, mounting evidence points to the deleterious effects of BPS on a wide range of neuroendocrine functions in animals. In addition to its reproductive toxicity, recent experimental efforts indicate that BPS has a considerable potential to induce neurotoxicity and behavioral dysfunction. This review analyzes the current state of knowledge regarding the neurobehavioral effects of BPS and discusses its potential mode of actions on several aspects of the neuroendocrine system. We summarize the role of certain hormones and their signaling pathways in the regulation of brain and behavior and discuss how BPS induces neurotoxicity through interactions with these pathways. Finally, we review potential links between BPS exposure and aberrant neurobehavioral functions in animals and identify key knowledge gaps and hypotheses for future research.

Exposure to New Emerging Bisphenols Among Young Children in Switzerland

Restrictions on the use of bisphenol A (BPA) in consumer products led to its replacement by various bisphenol (BP) analogues, yet young children's exposure to these analogues has been poorly characterized so far. This study aimed to characterize infants' and toddlers' exposure to BPA and 14 emerging BP analogues (i.e., bisphenol AF, bisphenol AP, bisphenol B, bisphenol BP, bisphenol C (BPC), bisphenol E, bisphenol F (BPF), bisphenol G, bisphenol M (BPM), bisphenol P, bisphenol PH, bisphenol S (BPS), bisphenol TMC, and bisphenol Z). We extracted infants' and toddlers' urine from diapers (n = 109) collected in Swiss daycare centers as a practical and noninvasive alternative approach to urinary biomonitoring. Bisphenols were present in 47% of the samples, with BPC and BPM being the most frequently detected (23% and 25% of all samples, respectively). The mean concentrations of urinary BPS and BPF were greater than that of BPA. This contrasts with data reported previously. Furthermore, statistical analysis revealed a significant and negative correlation between urinary BPM concentration and the population's age. Our results provide a first characterization of infants' and toddlers' exposure to bisphenols in Switzerland. This knowledge can be used to support ongoing biomonitoring studies and to prioritize exposure reduction and prevention strategies.

Plastics derived endocrine-disrupting compounds and their effects on early development

Despite the fact that the estrogenic effects of bisphenols were first described 80 years ago, recent data about its potential negative impact on birth outcome parameters raises a strong rationale to investigate further. The adverse health effects of plastics recommend to measure the impacts of endocrine-disrupting compounds (EDCs) such as bisphenols (BPA, BPS, BPF), bis(2-ethylhexyl) phthalate, and dibutyl phthalate (DBP) in human health. Exposure to these compounds in utero may program the diseases of the testis, prostate, kidney and abnormalities in the immune system, and cause tumors, uterine hemorrhage during pregnancy and polycystic ovary. These compounds also control the processes of epigenetic transgenerational inheritance of adult-onset diseases by modulating DNA methylation and epimutations in reproductive cells. The early developmental stage is the most susceptible window for developmental and genomic programming. The critical stages of the events for a normal human birth lie between the many transitions occurring between spermatogenesis, egg fertilization and the fully formed fetus. As the cells begin to grow and differentiate, there are critical balances of hormones, and protein synthesis. Data are emerging on how these plastic-derived compounds affect embryogenesis, placentation and feto-placental development since pregnant women and unborn fetuses are often exposed to these factors during preconception and throughout gestation. Impaired early development that ultimately influences fetal outcomes is at the center of many developmental disorders and contributes an independent risk factor for adult chronic diseases. This review will summarize the current status on the impact of exposure to plastic derived EDCs on the growth, gene expression, epigenetic and angiogenic activities of the early fetal development process and their possible effects on birth outcomes.