Effects of bisphenol A and its analogs on reproductive health: A mini review

Changes Caused by Low Doses of Bisphenol A (BPA) in the Neuro-Chemistry of Nerves Located in the Porcine Heart

Simple Summary

Bisphenol A (BPA) is a substance commonly used in the plastics industry, which is a part of many everyday items. It may leach from plastics and penetrate food, water, soil and air. It is known that BPA negatively affects living organisms. It impairs the functions of the intestine, neurons, reproductive organs, endocrine glands and immune cells. Previous studies have also reported that BPA negatively influences the cardiovascular system, leading to heart arrhythmia, intensification of atherosclerosis, blood hypertension and increased risk of a heart attack. However, many aspects of the influence of BPA on the heart are still poorly understood. One of these aspects is the BPA impact on heart innervation. Therefore, this article aimed to investigate the influence of low doses of BPA on the number of nerves containing selected active substances taking part in neuronal stimuli conduction located in the porcine heart apex. The results indicate that even relatively low doses of BPA are not neutral to the cardiovascular system, because they affect the neurochemical characterization of nerves in the heart. These changes may underlie the negative effects of BPA on the heart.

Abstract

Bisphenol A (BPA) contained in plastics used in the production of various everyday objects may leach from these items and contaminate food, water and air. As an endocrine disruptor, BPA negatively affects many internal organs and systems. Exposure to BPA also contributes to heart and cardiovascular system dysfunction, but many aspects connected with this activity remain unknown. Therefore, this study aimed to investigate the impact of BPA in a dose of 0.05 mg/kg body weight/day (in many countries such a dose is regarded as a tolerable daily intake–TDI dose of BPA–completely safe for living organisms) on the neurochemical characterization of nerves located in the heart wall using the immunofluorescence technique. The obtained results indicate that BPA (even in such a relatively low dose) increases the number of nerves immunoreactive to neuropeptide Y, substance P and tyrosine hydroxylase (used here as a marker of sympathetic innervation). However, BPA did not change the number of nerves immunoreactive to vesicular acetylcholine transporter (used here as a marker of cholinergic structures). These observations suggest that changes in the heart innervation may be at the root of BPA-induced circulatory disturbances, as well as arrhythmogenic and/or proinflammatory effects of this endocrine disruptor. Moreover, changes in the neurochemical characterization of nerves in the heart wall may be the first sign of exposure to BPA.

Dietary Intake of Endocrine Disrupting Substances Presents in Environment and Their Impact on Thyroid Function

According to the available data, environmental pollution is a serious problem all over the world. Between 2015 and 2016, pollution was responsible for approximately nine million deaths worldwide. They also include endocrine disrupting chemicals (EDCs) that can interfere with the functioning of the thyroid gland. They are characterized by high persistence in the environment. These substances can enter the body through the gastrointestinal tract, respiratory system, as well as contact with the skin and overcome the placental barrier. EDC can be found in food, water, and personal care products. They can get into food from the environment and as a result of their migration to food products and cosmetics from packaging. EDCs can disrupt the functioning of the thyroid gland through a number of mechanisms, including disrupting the activation of thyroid receptors and the expression of genes that are related to the metabolism, synthesis, and transport of thyroid hormones (HT). There is a need to strengthen the food safety policy that aimed at the use of appropriate materials in direct contact with food. At the same time, an important action is to reduce the production of all waste and, when possible, use biodegradable packaging, which may contribute to the improvement of the quality of the entire ecosystem and the health of food, thus reducing the risk of developing thyroid diseases.

Structural and chemical role of mesenchymal stem cells and resveratrol in regulation of apoptotic -induced genes in Bisphenol-A induced uterine damage in adult female albino rats

The probable beneficial effects of mesenchymal stem cells (MSCs) and resveratrol were assessed in an experimental model of Bisphenol-A (BPA)-evident uterine damage in rats. Thirty-five albino rats were involved and equally divided into five groups: Group I: negative control rats received usual diet, Group II: positive control rats received BPA by oral gavage for 15 days, Group III: BPA-treated rats received single oral gavage of resveratrol daily for two weeks, Group IV: BPA-treated rats received a single intravenous dose of MSCs and Group V: BPA-treated rats received combined treatment of resveratrol and MSCs. Oxidative stress markers, apoptosis-related genes, and gonadal hormones were assessed. Histological and immunohistochemical examination of uterine tissue was conducted for TGF-β 1. Caspases-3, 8, and 9 (Casp3, Casp8, Casp9) genes were assessed in uterine tissues by quantitative real-time PCR. Results revealed that BPA induced significant changes in the endometrial tissue, inflammatory cell infiltration, focal blood extravasation, increase in collagen fibers, decrease in PAS staining, and increase in TGF-β 1 immunoreactivity. BPA also induced a significant increase in oxidative stress markers; malondialdehyde (MDA), SOD, CAT, and apoptosis-related genes. BPA induced a significant change in blood levels of gonadal hormones; a significant increase in FSH and a significant decrease in estradiol (E2) and progesterone (P). Treatment with either resveratrol, MSCs, or a combination of them resulted in significant enhancement of histological findings, restoration of gonadal hormones to near-normal levels, and a significant decrease in oxidative stress markers and apoptosis genes. Combined treatment with resveratrol and MSCs demonstrated more significant therapeutic effects as regard to the studied parameters in association with rat groups treated with either MSCs or resveratrol separately.

Multisystemic alterations in humans induced by bisphenol A and phthalates: Experimental, epidemiological and clinical studies reveal the need to change health policies

A vast amount of evidence indicates that bisphenol A (BPA) and phthalates are widely distributed in the environment since these compounds are mass-produced for the manufacture of plastics and plasticizers. These compounds belong to a large group of substances termed endocrine-disrupting chemicals (EDC). It is well known that humans and living organisms are unavoidably and unintentionally exposed to BPA and phthalates from food packaging materials and many other everyday products. BPA and phthalates exert their effect by interfering with hormone synthesis, bioavailability, and action, thereby altering cellular proliferation and differentiation, tissue development, and the regulation of several physiological processes. In fact, these EDC can alter fetal programming at an epigenetic level, which can be transgenerational transmitted and may be involved in the development of various chronic pathologies later in the adulthood, including metabolic, reproductive and degenerative diseases, and certain types of cancer. In this review, we describe the most recent proposed mechanisms of action of these EDC and offer a compelling selection of experimental, epidemiological and clinical studies, which show evidence of how exposure to these pollutants affects our health during development, and their association with a wide range of reproductive, metabolic and neurological diseases, as well as hormone-related cancers. We stress the importance of concern in the general population and the urgent need for the medical health care system to closely monitor EDC levels in the population due to unavoidable and involuntary exposure to these pollutants and their impact on human health.

Nonfunctional adrenal incidentalomas may be related to bisphenol-A

PURPOSE

Bisphenol-A (BPA) is an endocrine-disrupting chemical that may affect the hormones and their receptors. The aim of this study is to determine whether BPA has an effect on the development of nonfunctional adrenal incidentaloma (NFAI).

METHODS

Fifty patients who were admitted to endocrinology outpatient clinics and diagnosed as NFAI were included in the study. Fifty healthy people without adrenal mass and adrenal pathology in the upper abdominal computerized tomography or magnetic resonance imaging were also included as control group. Age, gender and body mass index of the study groups were similar. The serum samples for BPA were stored at -80 °C in refrigerator until working in the lab. Serum BPA levels were measured using ELISA technique.

RESULTS

Mean serum BPA level was 7.06 ± 3.96 ng/ml in NFAI patients and 4.79 ± 3.01 ng/ml in control group. Serum BPA level was significantly higher in NFAI group than control group (p = 0.001). Serum BPA levels were also found to be significantly higher in women with NFAI than in men with NFAI (p = 0.019).

CONCLUSIONS

The mechanisms of NFAI development have not been clarified yet. Increased BPA exposure with developed industrialization may play a role in NFAI formation. For the reduction of BPA exposure, the use of plastic prepacked products, plastic containers, and safety measures are essential for public health.

Adsorption of emerging contaminants from water and wastewater by modified biochar: A review

Emerging contaminants (ECs), a group of relatively low-concentration but high-toxicity pollutants in the environment, have attracted widespread attention in recent years. These trace pollutants can be enriched in organisms and finally transferred to human bodies, posing a potential hazard to public health. Biochar, a low-cost and high-efficiency adsorbent, has been used to treat ECs in water. However, due to certain limitations of pristine biochar, such as poor adsorption capacity, narrow adsorption range, and other shortcomings, it is necessary to modify biochar to improve its applications in water treatment for ECs. Currently, there are a lot of reports on the removal of ECs from water by modified biochar. These studies explored different modification methods to functionalize biochar with various physicochemical properties, which resulted in distinct adsorption effects, behaviors and mechanisms of modified biochar on different ECs. There is a need to systematically review and digest the knowledge on the adsorption of ECs on modified biochar. In this review, recent biochar modification methods used in ECs removal are firstly summarized, and the adsorption performance and mechanisms of modified biochar on typical ECs are then systematically reviewed. Finally, the main research directions and trends, as well as recommendations and suggestions for future development are pointed out.

Presence of Parabens and Bisphenols in Food Commonly Consumed in Spain

Given the widespread use of bisphenols and parabens in consumer products, the assessment of their intake is crucial and represents the first step towards the assessment of the potential risks that these compounds may pose to human health. In the present study, a total of 98 samples of food items commonly consumed by the Spanish population were collected from different national supermarkets and grocery stores for the determination of parabens and bisphenols. Our analysis demonstrated that 56 of the 98 food samples contained detectable levels of parabens with limits of quantification (LOQ) between 0.4 and 0.9 ng g-1. The total concentration of parabens (sum of four parabens: ∑parabens) ranged from below the LOQ to 281.7 ng g-1, with a mean value of 73.86 ng g-1. A total of 52% of the samples showed detectable concentrations of bisphenols. Bisphenol A (BPA) was the most frequently detected bisphenol in the food samples analysed, followed by bisphenol S (BPS) and bisphenol E (BPE). Bisphenol AF (BPAF), bisphenol B (BPB) and bisphenol P (BPP) were not found in any of the analysed samples. LOQ for these bisphenols were between 0.4 and 4.0 ng g-1.

Prenatal exposure to bisphenol S and altered newborn mitochondrial DNA copy number in a baby cohort study: Sex-specific associations

Bisphenol S (BPS) is a main substitute for bisphenol A, which are ubiquitous in human daily products. Newborn mitochondrial DNA copy number (mtDNAcn) is considered as a marker for biological aging and human health, and has been related to diseases in later life. We recruited 762 mother-newborn pairs in a birth cohort study between 2013 and 2015 in Wuhan, China. Urinary BPS concentrations were detected using ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). MtDNAcn from cord blood was measured by quantitative real-time polymerase chain reaction (qPCR). We applied multiple informant models based on generalized estimating equations to assess the associations between prenatal BPS exposure and mtDNAcn. The median urine concentrations of BPS were 0.32 μg/L, 0.34 μg/L, and 0.36 μg/L in the first, second, and third trimesters, respectively. In the multiple informant models, we observed significant associations between BPS and mtDNAcn among male newborns. Compared with the lowest quarters, the second, third, and the highest quarter of BPS level were associated with 58.00% (95% CI: 76.58%, -24.66%), 64.65% (95% CI: 79.40%, -39.33%) and 59.07% (95% CI: 75.16%, -32.58%) reductions of mtDNAcn in the first trimester, respectively. No significant associations were found in the second and third trimesters. The associations between BPS and mtDNAcn were not found among female newborns. Findings from this study suggested that BPS exposure was related to decreased mtDNAcn in male newborns. The first trimester was identified as the critical windows for BPS exposure during pregnancy.

Sex-specific associations of prenatal exposure to bisphenol A and its alternatives with fetal growth parameters and gestational age

BACKGROUND

Bisphenol A (BPA) can cause detrimental effects on fetal growth. However, the effects of BPA alternatives, such as bisphenol F (BPF) and bisphenol S (BPS), on fetal growth are less known.

OBJECTIVE

To investigate the relationships of prenatal BPA, BPF, and BPS exposures with fetal growth parameters and gestational age.

METHODS

Urinary BPA, BPF, and BPS were measured in 1,197 pregnant women before delivery in a Chinese cohort. The associations of prenatal exposure to BPA, BPF, and BPS with fetal growth parameters and gestational age were examined, and associations stratified by fetal sex were also conducted. We used a restricted cubic splines (RCS) model to examine the dose-response associations between exposures and outcomes.

RESULTS

Maternal urinary BPA and BPF were negatively related to birth length (-0.30 cm, 95% CI: -0.44, -0.15 and -0.21 cm, 95% CI: -0.36, -0.07 comparing the extreme exposure groups, respectively, both p for trends < 0.01). These associations were more pronounced in girls with inverted U-shaped dose-response relationships. Maternal urinary BPA and BPF were positively related to ponderal index (0.05 g/cm³ × 100, 95% CI: 0.01, 0.09 and 0.04 g/cm³ × 100, 95% CI: 0.01, 0.08 comparing the extreme exposure groups, respectively, both p for trends = 0.02), and maternal urinary BPS was associated with shorter gestational age (-0.20 weeks, 95% CI: -0.37, -0.03 comparing the extreme exposure groups, p for trend = 0.02). These associations were only observed in girls and exhibited a linear dose-response relationship.

CONCLUSIONS

Prenatal BPA, BPF, and BPS exposures were associated with detrimental effects on fetal growth parameters, and stronger effects were noted in female infants.

Molecular and cellular responses to short exposure to bisphenols A, F, and S and eluates of microplastics in C. elegans

Bisphenol F (BPF) and bisphenol S (BPS) have been developed as an alternative to bisphenol A (BPA), a well-known endocrine disruptor, leading to their detection in the aquatic environment. In this work, we used the animal model Caenorhabditis elegans to improve our understanding of their potential effects on the biota and the environment. Our findings demonstrated that, after 24 h exposure, all the bisphenols examined increased the number of apoptotic corpses and the expression of the detoxifying enzymes SOD-3 and GST-4, without affecting the ROS levels, while BPA and BPS significantly enhanced DNA fragmentation. Furthermore, similarly to BPA, BPF and BPS did not alter the lifespan through the activation of SEK-1 and SKN-1 pathways. Thus, this study raises the attention of the risks associated with exposure to BPA alternatives. We also examined the effects of microplastic (MP) eluates on C. elegans. Aqueous extracts of weathered microplastic samples, both at high and low degradation state and pellets, have been evaluated for their effects on lifespan, DNA fragmentation, germline apoptosis, and oxidative stress response. Overall, our findings showed that eluates of low degraded plastics exert a greater toxic effect on the nematode C. elegans compared with the aqueous sample of high degraded plastic fragments and pellets.

A simple fluorescence anisotropy assay for detection of bisphenol A using fluorescently labeled aptamer

Bisphenol A (BPA) is one of the environmental endocrine disruptors (EDCs), and BPA contamination in environment can cause high risks to human health. Rapid determination of BPA on sites is in high demand in environmental analysis. Taking advantage of aptamers as affinity ligands and fluorescence anisotropy (FA) analysis, we developed a simple and rapid FA assay for BPA by employing a single tetramethylrhodamine (TMR) labeled short 35-mer DNA aptamer against BPA. The assay is based on the BPA-binding induced conformation change of TMR-labeled aptamer and alteration of interaction between TMR and guanine bases, resulting in change of FA signals. We screened the FA change of aptamer probes having TMR label on a specific site of the aptamer upon BPA addition. The aptamer with a TMR label on the 22nd T base showed large FA-decreasing response to BPA and maintained good binding affinity to BPA. By using this TMR-labeled aptamer, we achieved FA detection of BPA with a detection limit of 0.5 μmol/L under the optimized conditions. This assay was selective towards BPA and enabled the detection of BPA spiked in tap water sample, showing the potential applications on water samples.

Taurine effects on Bisphenol A-induced oxidative stress in the mouse testicular mitochondria and sperm motility

Objectives:

This study was performed to investigate the protective effects of taurine (2-aminoethanesulfonic acid, TAU) on oxidative stress in the isolated mouse testicular mitochondria, mitochondrial membrane potential (MMP), viability and motility of the exposed sperms to the BPA.

Methods:

We treated epididymal spermatozoa obtained from mice and isolated mouse testicular mitochondria with BPA (0.8 mmol/mL) and various doses of TAU (5, 10, 30 and 50 µmol/L). We used the MTT assay and Rhodamine 123 uptake to assess sperm viability and MMP. We assessed the oxidative stress through measuring ROS (reactive oxygen species), MDA (malondialdehyde), GSH (glutathione), and SOD (super-oxide dismutase) levels in the testicular mitochondrial tissue.

Results:

BPA significantly elevated ROS, MDA and MMP levels, and markedly reduced SOD and GSH levels in the isolated mitochondria. BPA also considerably impaired spermatozoa viability and motility. Pretreatment with 30 and 50 µmol/L of TAU could considerably suppressed mitochondrial oxidative stress, enhanced MMP, and improved sperm motility and viability.

Conclusion:

TAU may attenuate the BPA-induced mitochondrial toxicity and impaired sperm motility via decreasing oxidative stress.

A validated search filter for the identification of endocrine disruptors based on the ECHA/EFSA guidance recommendations

A guidance document for the identification of endocrine disruptors (EDs) in the regulatory assessment of plant protection products (PPP) and biocidal products (BP) has been published by the European Chemical Agency (ECHA) and the European Food Safety Authority (EFSA). The ECHA/EFSA guidance, mainly addressing EATS (estrogen, androgen, thyroid, steroidogenesis) modalities, is intended to guide applicants and assessors of the competent regulatory authorities on the implementation of the scientific criteria for the determination of ED properties pursuant to the recently implemented PPP (EU 2018/605) and BP (EU 2017/2100) EU Regulations. In this study, a search filter for targeted literature search in context of assessing if a substance can be identified as an ED relevant for human health was developed and validated. Development of the search filter was based on the search strategy presented in the ECHA/EFSA guidance and using the estrogenic chemical Bisphenol AF (BPAF) as a model substance. Information specialists from two independent institutions developed refined search filters based on the suggested original search strategy published (ECHA/EFSA guidance - Appendix F). Articles identified by a systematic literature search for BPAF were screened for relevance with inclusion and exclusion criteria by two independent reviewers obtaining positive (relevant) and negative (irrelevant) controls. The developed search filter was quantitatively evaluated in terms of sensitivity, specificity and precision based on the positive and negative controls. The developed filter was then validated for T modality by its application to the known thyroid-disruptor perchlorate. The result is a sensitive search filter with sufficient specificity, which can be applied for all chemicals where a targeted literature search is needed to assess and identify ED properties of chemicals with relevance for humans. Future application of the filter to a broader range of chemicals may identify further points of improvement.

Perinatal oral exposure to low doses of bisphenol A, S or F impairs immune functions at intestinal and systemic levels in female offspring mice

BACKGROUND

Bisphenol A (BPA), one of the highest-volume chemicals produced worldwide, has been identified as an endocrine disruptor. Many peer-reviewing studies have reported adverse effects of low dose BPA exposure, particularly during perinatal period (gestation and/or lactation). We previously demonstrated that perinatal oral exposure to BPA (via gavage of mothers during gestation and lactation) has long-term consequences on immune response and intestinal barrier functions. Due to its adverse effects on several developmental and physiological processes, BPA was removed from consumer products and replaced by chemical substitutes such as BPS or BPF, that are structurally similar and not well studied compare to BPA. Here, we aimed to compare perinatal oral exposure to these bisphenols (BPs) at two doses (5 and 50 μg/kg of body weight (BW)/day (d)) on immune response at intestinal and systemic levels in female offspring mice at adulthood (Post Natal Day PND70).

METHODS

Pregnant female mice were orally exposed to BPA, BPS or BPF at 5 or 50 μg/kg BW/d from 15th day of gravidity to weaning of pups at Post-Natal Day (PND) 21. Humoral and cellular immune responses of adult offspring (PND70) were analysed at intestinal and systemic levels.

RESULTS

In female offspring, perinatal oral BP exposure led to adverse effects on intestinal and systemic immune response that were dependant of the BP nature (A, S or F) and dose of exposure. Stronger impacts were observed with BPS at the dose of 5 μg/kg BW/d on inflammatory markers in feces associated with an increase of anti-E. coli IgG in plasma. BPA and BPF exposure induced prominent changes at low dose in offspring mice, in term of intestinal and systemic immune responses, provoking an intestinal and systemic Th1/Th17 inflammation.

CONCLUSION

These findings provide, for the first time, results of long-time consequences of BPA, S and F perinatal exposure by oral route on immune response in offspring mice. This work warns that it is mandatory to consider immune markers and dose exposure in risk assessment associated to new BPA's alternatives.

Oxidative stress in bisphenol AF-induced cardiotoxicity in zebrafish and the protective role of N-acetyl N-cysteine

Research has shown that there is a relationship between bisphenol A (BPA) exposure and the incidence of cardiovascular diseases. However, the effect of bisphenol AF (BPAF), a main substitute for BPA, on heart development remains unclear. In this study, the cardiotoxicity of BPAF was evaluated in zebrafish in vivo and in human cardiac myocytes (HCMs) in vitro. Our results showed that BPAF at a concentration of 200 μg/L results in cardiotoxicity, including a reduced number of cardiomyocytes and endocardial cells in the heart, and reduced heart size in two transgenic zebrafish models (myl7:: dsred2-nuc and fli1a::nGFP). An increase in apoptosis was observed along with antioxidant enzyme inhibition and lipid peroxidation. In addition, the mRNA expression levels of several key genes involved in cardiac development were suppressed by BPAF treatment. In the HCM cell model, BPAF at 2 mg/L induced reactive oxygen species generation, antioxidant enzyme inhibition, mitochondrial dysfunction and oxidative DNA damage. These adverse outcomes can be attenuated by the antioxidant N-acetyl-L-cysteine (NAC), suggesting that oxidative stress is involved in BPAF-induced cardiotoxicity. These data indicated that BPAF exposure increased oxidative stress and apoptosis and that it suppressed the expression of genes involved in cardiac development, which may play crucial roles in the mechanisms of BPAF-induced cardiotoxicity.

Long-term bisphenol S exposure aggravates non-alcoholic fatty liver by regulating lipid metabolism and inducing endoplasmic reticulum stress response with activation of unfolded protein response in male zebrafish

Environmental chemical exposures have been implicated as risk factors for the development of non-alcoholic fatty liver (NAFLD). Bisphenol S (BPS), widely used in multitudinous consumer products, could disrupt lipid metabolism in the liver. This study aimed at examining the hypothesis that long-term exposure to BPS promotes the development of liver fibrosis and inflammation by means of the application of a semi-static exposure experiment that exposed zebrafish to 1, 10, and 100 μg/L BPS from 3 h post fertilization to 120 day post fertilization. Results showed that the 120-d BPS exposure elevated plasma aspartate aminotransferase and alanine aminotransferase activities, increased triacylglycerol (TAG) and total cholesterol levels in male liver, and even induced hepatic apoptosis and fibrosis. Hepatic lipid accumulation observed in the 30-d BPS-exposed zebrafish was recovered after a 90-d depuration phase, thereby indicating that long-term BPS exposure promotes the progression of simple steatosis to non-alcoholic steatohepatitis. Furthermore, BPS exposure for 120-d promoted the synthesis of TAG and lipotoxic free fatty acids by elevating the transcription of srebp1, acc, fasn, and elovl6, induced endoplasmic reticulum (ER) stress with increasing expression levels of unfolded protein response (UPR) genes (perk, hsp5, atf4a, and ddit3), and then stimulated the expression of two key autophagy genes (atg3 and lc3) and inflammatory genes (il1b and tnfα). It is indicated that BPS can induce the development of steatohepatitis via the activation of the PERK-ATF4a pathway of the UPR. Data gathered suggest that environmental pollutants-induced ER stress with the activation of UPR can potentially trigger the NAFLD development in males. Overall, our study provided new sights into understanding of the adverse health effects of metabolism disrupting chemicals.

Developmental Exposure to Tetrabromobisphenol A Has Minimal Impact on Male Rat Reproductive Health

The flame retardant and plasticizer, tetrabromobisphenol-A (TBBPA) has rapidly become a common component in the manufacture of circuit boards and plastics worldwide. It is also an analog of bisphenol A (BPA), an endocrine disrupting chemical identified by the Endocrine Society. As such, TBBPA needs to be investigated for similar potential human health risks. Using rats as a model, we exposed pregnant dams and their progeny to 0, 0.1, 25, or 250 mg TBBPA/kg of body weight until the offspring reached adulthood and assessed the first generation of males for any reproductive tract abnormalities. We found no differences in the morphology of testes, sperm, prostates, or secondary sex organs from post-natal day 21 through one-year of age. A delay in the time to preputial separation was found with the 250 mg/kg treatment. Also, minor differences of sperm count at one-year old with the 25 mg/kg treatment and expression levels of two steroidogenic pathway enzymes at either post-natal day 90 or one-year old in the 250 mg/kg treatment group were detected, but spermatogenesis was not disrupted. While these results may lead to the supposition that TBBPA is less harmful than its parent compound BPA, more studies need to be conducted to assess long-term exposure effects.

Association of prenatal exposure to bisphenols and birth size in Zhuang ethnic newborns

Prenatal exposure to bisphenol A (BPA) and its analogues can affect fetal growth and development. However, epidemiologic findings were inconsistent and there was a lack of study for BPA analogues. We aimed to examine the associations between prenatal exposure to BPA, bisphenol B (BPB), bisphenol F (BPF), bisphenol S (BPS), and tetrabromobisphenol A (TBBPA) and birth size. 2023 mother-infant pairs were included in this study. The associations between serum bisphenol levels and birth size were analyzed by multivariate linear regression models. After adjusting for covariates, one log10-unit increase in serum BPA was correlated with a 32.10 g (95% CI: -61.10, -3.10) decrease in birth weight for all infants, and the inverse association was only observed in males when stratified analysis by gender. Additionally, higher BPF concentrations were associated with decreasing birth weight (P for trend = 0.031), ponderal index (P for trend = 0.021), and birth weight Z-scores (P for trend = 0.039) in all infants, and the inverse associations were also only observed in males when stratified analysis by gender. Similarly, higher TBBPA levels were also correlated with decreased birth weight (P for trend = 0.023). However, after gender stratification, higher TBBPA concentrations were associated with a decrease in birth weight (P for trend = 0.007), birth length (P for trend = 0.026), and birth weight Z-scores (P for trend = 0.039) in males. Our data suggested an inverse association of prenatal exposure to BPA, BPF, and TBBPA and birth size, which may be more pronounced in male infants.

Endocrine disruption: Molecular interactions of environmental bisphenol contaminants with thyroid hormone receptor and thyroxine-binding globulin

Many bisphenol A (BPA) analogs have been commercially used recently, such as 2,2-bis(4-hydroxyphenyl)butane (BPB), 4,4′-ethylidenebisphenol, 4,4′-methylenediphenol (BPF), 4,4′-(1,4-phenylenediisopropylidene)bisphenol (BPP), 4,4′-dihydroxydiphenyl sulfone (BPS), 4,4′-cyclohexylidenebisphenol (BPZ), 4,4′-(hexafluoroisopropylidene)diphenol (BPAF), 4,4′-(1-phenylethylidene)bisphenol (BPAP), and 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane (TMBPA), to circumvent adverse effects of BPA. However, their increasing use is also contaminating the environment, which is a potential cause of concern for human health. Thyroid hormone transport and signaling are potential targets for endocrine-disrupting activity of BPA analogs. Thyroxine-binding globulin (TBG) is the major carrier protein for thyroxine (T4) and triiodothyronine (T3) in blood. Thyroid hormones exert their action through thyroid hormone receptors (TRα and TRβ). This report presents the thyroid-disrupting potential of indicated nine BPA analogs from structure-based studies with TBG and TRα. Each BPA analog formed important polar and hydrophobic interactions with a number of residues of TBG and TRα. Majority of TBG residues (77–100%) and TRα residues (70–91%) interacting with BPA analogs were common with those of native ligands T4 and T3, respectively. Majority of BPA analogs interacted with TBG forming a salt bridge interaction at Lys-270. The hydrogen-bonding interaction of T3 with TRα at His-381 was also shared by majority of analogs. The binding energy for BPP, BPB, BPZ, BPAP, and TMBPA with both proteins was closer to binding energy of respective native ligands. The similarity in structural binding characteristics suggested potential disrupting activity of thyroid hormone signaling and transport.

Low doses of Bisphenol S affect post-translational modifications of sperm proteins in male mice

BACKGROUND

Bisphenol S (BPS) is increasingly used as a replacement for bisphenol A in the manufacture of products containing polycarbonates and epoxy resins. However, further studies of BPS exposure are needed for the assessment of health risks to humans. In this study we assessed the potential harmfulness of low-dose BPS on reproduction in male mice.

METHODS

To simulate human exposure under experimental conditions, 8-week-old outbred ICR male mice received 8 weeks of drinking water containing a broad range of BPS doses [0.001, 1.0, or 100 μg/kg body weight (bw)/day, BPS1-3] or vehicle control. Mice were sacrificed and testicular tissue taken for histological analysis and protein identification by nano-liquid chromatography/mass spectrometry (MS) and sperm collected for immunodetection of acetylated lysine and phosphorylated tyrosine followed by protein characterisation using matrix-assisted laser desorption ionisation time-of-flight MS (MALDI-TOF MS).

RESULTS

The results indicate that compared to vehicle, 100 μg/kg/day exposure (BPS3) leads to 1) significant histopathology in testicular tissue; and, 2) higher levels of the histone protein γH2AX, a reliable marker of DNA damage. There were fewer mature spermatozoa in the germ layer in the experimental group treated with 1 μg/kg bw (BPS2). Finally, western blot and MALDI-TOF MS studies showed significant alterations in the sperm acetylome and phosphorylome in mice treated with the lowest exposure (0.001 μg/kg/day; BPS1), although the dose is several times lower than what has been published so far.

CONCLUSIONS

In summary, this range of qualitative and quantitative findings in young male mice raise the possibility that very low doses of BPS may impair mammalian reproduction through epigenetic modifications of sperm proteins.

The Effect of Exposure to Bisphenol A on Spermatozoon and the Expression of Tight Junction Protein Occludin in Male Mice

Although bisphenol A (BPA) has been associated with impaired spermatogenesis, the mechanisms remain unclear. Tight junction occludin plays important roles in spermatogenesis. The objective of the present study was to explore the effects of BPA exposure in adolescent mice. Male mice were orally treated with low-dose (0.05 mg/kg/d), middle-dose (5.0 mg/kg/d), or high-dose (50 mg/kg/d) BPA in corn oil from postnatal day (PND) 35 to 65. Animals were killed on PND 65 and PND 125. On PND 65, the sperm count, sperm motility, and the expression of occludin showed a dose-related decline. On PND 125, the sperm count, sperm motility, and the expression of occludin were in recovery. However, there remained significant decreases in these parameters in the 50 mg/kg/d group on PND 125 compared with the control. The dose-related effects on the measured parameters and occludin expression suggest an early suppressive or damaging effect on the blood–testis barrier followed by recovery after dosing ceased. At a BPA dose of 50 mg/kg/d, recovery did not occur, suggesting that higher doses of BPA may cause irreversible damage to reproduction in male mice.

Subchronic toxicity of bisphenol A on the architecture of spleen and hepatic trace metals and protein profile of adult male Wistar rats

Bisphenol A (BPA) is one of the widely used chemical as a plasticizer and regarded as endocrine disruptor because of its ability to derail body metabolic functions and adverse effect on the vital organs. The present work outlined the subchronic effect of low-dose BPA (10 mg/kg) on histology of spleen, level of hepatic trace metals, and hepatic protein profile of Wistar rats. To conduct the research work, animals were grouped into two categories (n = 5). Group 1 was labelled as the control group and group 2 was taken as an experimental group. Experimental group was exposed to low-dose BPA for 12 weeks. Histopathology of spleen highlighted dilation in splenic sinuses, follicle activation, followed by depopulation in the area of white pulp and red pulp in the experimental group. Iron staining revealed significant hemosiderosis in the experimental group when compared with the control group. Statistically significant decrease was noted in zinc and copper concentrations, while nonsignificant change was observed for magnesium concentration through atomic absorption spectroscopy. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was run for hepatic protein profiling, and as compared to control, elevated levels of different proteins were observed in the experimental group. It can be concluded from the above results that even low dose of BPA causes changes in the major organs of the body. Hence, it is suggested that BPA alternative should be used, so that public health status can be secured.

Evaluation of the effects of low concentrations of bisphenol AF on gonadal development using the Xenopus laevis model: A finding of testicular differentiation inhibition coupled with feminization

Developmental exposures to estrogenic chemicals possibly cause structural and functional abnormalities of reproductive organs in vertebrates. Bisphenol AF (BPAF), a bisphenol A (BPA) analogue, has been shown to have higher estrogenic activity than BPA, but little is known about the effects of BPAF on gonadal development, particularly gonadal differentiation. We aimed to determine whether low concentrations of BPAF could disrupt gonadal differentiation and subsequent development using Xenopus laevis, a model species for studying feminizing effects of estrogenic chemicals. X. laevis tadpoles were exposed to BPAF (1, 10, 100 nM) or 17β-estradiol (E2, positive control) from stages 45/46 to 53 and 66 in a semi-static exposure system, with a prolonged treatment with the highest concentration to the eighth week post-metamorphosis (WPM8). Gonadal morphology and histology as well as sexually dimorphic gene expression were examined to evaluate the effects of BPAF. All concentrations of BPAF caused changes in testicular morphology at different developmental stages compared with controls. Specifically, at stage 53, BPAF like E2 resulted in decreases in both the size and the number of gonadal metameres (gonomeres) in testes, looking like ovaries. Some of BPAF-treated testes remained segmented and even became discontinuous and fragmented at subsequent stages. Histological abnormalities were also observed in BPAF-treated testes, such as ovarian cavity at stages 53 and 66 and poorly developed seminiferous tubules on WPM8. At the molecular level, BPAF inhibited expression of male highly expressed genes in testes at stage 53. Correspondingly, BPAF, like E2, inhibited cell proliferation in testes at stage 50. All results show that low concentrations of BPAF inhibited testicular differentiation and subsequent development in X. laevis, along with feminizing effects to some degree. Our finding implies a risk of BPAF to the male reproductive system of vertebrates including humans.

Transcriptomic Responses of Bisphenol S Predict Involvement of Immune Function in the Cardiotoxicity of Early Life-Stage Zebrafish (Danio rerio)

Bisphenol S (BPS), an alternative for bisphenol A (BPA) that is present in thermal paper and numerous consumer products, has been linked to estrogenic, cytotoxic, genotoxic, neurotoxic, and immunotoxic responses. However, the mechanisms of BPS toxicity remain poorly understood. Here, following exposure to environmentally relevant concentrations ranging from 0.1 to 100 μg/L BPS, transcriptional changes evaluated by enriched gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Ingenuity Pathway Analysis (IPA) predicted cardiac disease and impairment of immune function in zebrafish at the embryo-to-larvae stage. Consistent with impacts predicted by transcriptional changes, significant sublethal impacts were observed ranging from reduced heart rate [8.7 ± 2.4% reductions at 100 μg/L BPS treatment; P < 0.05] to abnormal cardiac morphology [atrial/ventricle area significantly increased; 36.2 ± 9.6% at 100 μg/L BPS treatment; P < 0.05]. RNA-sequencing analysis results also indicated changes in nitric oxide synthetase (NOS2) and interleukin 12 (IL12) after BPS treatment, which was confirmed at the protein level. Increased expression of other cytokine genes was observed in larvae, suggesting inflammatory responses may be contributing to cardiac impairment by BPS. BPS caused cardiotoxicity, which temporally corresponded with inflammatory responses as predicted from RNA sequencing and confirmed at the protein and cellular levels of biological organization. Additional study is needed to find causal linkages between these responses.

Assessment of Bisphenol A Levels in Preschool Children: Results of a Human Biomonitoring Study in Ankara, Turkey

OBJECTIVE

There is general concern regarding environmental chemical exposure and the impact it may have on human health. This is particularly important for vulnerable populations such as infants and children during critical periods of development. Bisphenol A (BPA) is an endocrine disrupting chemical used worldwide over the last 30 years in many consumer products. Evidence points to widespread human exposure to BPA. The aim of this study was to evaluate the exposure of Turkish preschool children to BPA.

METHODS

This study was conducted as a preliminary investigation of BPA in urine, collected from 3-6 year old children living in Ankara. After spot urine samples were taken from preschool children, free BPA, β-D-glucuronide and total BPA were determined using high-performance liquid chromatography tandem mass spectrometry and adjusted by creatinine concentration.

RESULTS

Preschool children from Ankara (n=125; males n=70, females n=55; mean age: 4.50±1.26) were recruited. BPA was detected in 76.8% of children from Ankara city, with urinary concentrations ranging from < limit of quantification to 18.36 μg/g creatinine. Total BPA levels were not statistically different between boys (1.26 μg/g creatinine) and girls (2.24 μg/g creatinine) (p>0.05).

CONCLUSION

This study is an important contribution to the limited information about childhood exposure to BPA. The estimated daily BPA intake in this study is substantially lower than the European Food Safety Authority derived tolerable daily intake of 4 μg/kg BW/day.

Cross Sectional Study on Exposure to BPA and Phthalates and Semen Parameters in Men Attending a Fertility Center

Among the possible risk factors for male reproduction, exposure to phthalates and alkylphenols is widely documented. This study evaluated the possible association between chemical exposure and the quality of the seminal fluid of 105 subjects in a fertility clinic. The urinary levels of seven phthalate metabolites (monoethylphthalate, MEP; monobenzylphthalate, MBzP; mono n-butylphthalate, MnBP; mono-(2-ethylhexyl) phthalate, MEHP; mono(2-ethyl-5-hydroxyhexyl) phthalate, MEHHP; mono-n-octylphthalate, MnOP; mono-isononylphthalate, MiNP) and bisphenol A (BPA), were analysed by high performance liquid chromatography/tandem mass spectrometry HPLC/MS/MS. The regression analysis showed that the semen volume was positively associated with MnBP, MnOP and BPA levels while was negatively associated with MiNP levels. The sperm concentration had a significant inverse relationship with MEP levels. A negative association was found between the use of plastic containers for food storage (p = 0.037) and semen volume (3.06 vs. 2.30 mL as average values, never vs daily). A significant positive correlation emerged (p < 0.005) between the consumption of canned food and the levels of BPA (2.81 vs. 0.14 µg/g creat as average values, daily vs. never) and between the use of perfumes and levels of MEP (389.86 vs. 48.68 µg/g creat, as average values, daily vs. never). No further statistically significant associations were found, even considering the working activity. Some evidence emerged about the possible link between exposure and seminal fluid quality: further case/control or prospective studies will allow us to confirm this causality hypothesis.

Bisphenol A Diglycidyl Ether (BADGE) and Bisphenol Analogs, but Not Bisphenol A (BPA), Activate the CatSper Ca2+ Channel in Human Sperm

Aim: Evidence suggests that bisphenol A diglycidyl ether (BADGE), bisphenol A (BPA), and BPA analogs can interfere with human male fertility. However, the effect directly on human sperm function is not known. The CatSper Ca²⁺ channel in human sperm controls important sperm functions and is necessary for normal male fertility. Environmental chemicals have been shown to activate CatSper and thereby affect Ca²⁺ signaling in human sperm. BPA has previously been investigated for effects on Ca²⁺ signaling human sperm, whereas the effects of other BPA analogs are currently unknown. The aim of this study is thus to characterize the effect of BADGE, BPA, and the eight analogs BPG, BPAF, BPC, BPB, BPBP, BPE, BPF, BPS on Ca²⁺ signaling, and CatSper in human sperm. Methods: Direct effects of the bisphenols on Ca²⁺ signaling in human sperm cells were evaluated using a Ca²⁺ fluorimetric assay measuring changes in intracellular Ca²⁺. Effects via CatSper were assessed using the specific CatSper inhibitor RU1968. Effects on human sperm function was assessed using an image cytometry-based acrosome reaction assay and the modified Kremer's sperm-mucus penetration assay. Results: At 10 μM the bisphenols BPG, BPAF, BPC, BADGE, BPB, and BPBP induced Ca²⁺ signals in human sperm cells, whereas BPE, BPF, BPS, and BPA had no effect. The efficacy of the chemicals at 10 μM is BPG > BPAF > BPC > BADGE > BPB > BPBP. Dose-response relations of BPG, BPAF, BPC, BADGE, BPB, and BPBP yielded EC50-values in the nM-μM range. The induced Ca²⁺ signals were almost completely abolished using the CatSper inhibitor RU1968, indicating an effect of the bisphenols on CatSper. All bisphenols, except BPBP, were found to dose-dependently inhibit progesterone-induced Ca²⁺ signals, with BPG and BPAF displaying inhibition even in low μM doses. BPG and BPAF were shown to affect human sperm function in a progesterone-like manner. Conclusion: Our results show that the bisphenols BPG, BPAF, BPC, BADGE, BPB, and BPBP can affect Ca²⁺ signaling in human sperm cells through activation of CatSper. This could potentially disrupt human sperm function by interfering with normal CatSper-signaling and thus be a contributing factor in human infertility, either alone or in mixtures with other chemicals.

Maternal environmental exposure to bisphenols and epigenome-wide DNA methylation in infant cord blood

Maternal prenatal exposures, including bisphenol A (BPA), are associated with offspring's risk of disease later in life. Alterations in DNA methylation may be a mechanism through which altered prenatal conditions (e.g. maternal exposure to environmental toxicants) elicit this disease risk. In the Michigan Mother and Infant Pairs Cohort, maternal first-trimester urinary BPA, bisphenol F, and bisphenol S concentrations were tested for association with DNA methylation patterns in infant umbilical cord blood leukocytes (N = 69). We used the Illumina Infinium MethylationEPIC BeadChip to quantitatively evaluate DNA methylation across the epigenome; 822 020 probes passed pre-processing and quality checks. Single-site DNA methylation and bisphenol models were adjusted for infant sex, estimated cell-type proportions (determined using cell-type estimation algorithm), and batch as covariates. Thirty-eight CpG sites [false discovery rate (FDR) <0.05] were significantly associated with maternal BPA exposure. Increasing BPA concentrations were associated with lower DNA methylation at 87% of significant sites. BPA exposure associated DNA methylation sites were enriched for 38 pathways significant at FDR <0.05. The pathway or gene-set with the greatest odds of enrichment for differential methylation (FDR <0.05) was type I interferon receptor binding. This study provides a novel understanding of fetal response to maternal bisphenol exposure through epigenetic change.

Effects of Bisphenol A Exposure during Pregnancy and lactation on Hippocampal Function in Newborn Rats

Bisphenol A (BPA) is widely used in industrial production. It is closely related to the growth and development of the nervous system, and can enter the fetal circulation through the placental barrier, and can be secreted through breast milk. The development of nervous system is very important in fetus and neonatal period. The purpose of this study is to investigate the effects of different doses of BPA on learning and memory function of nervous system in rats. Pregnant rats were randomly divided into three treatment groups (control group, 5 mg/kg/d, 50 mg/kg/d). All animals received BPA from the discovery of pregnancy to 21 days after birth. Results had shown that after high concentration BPA exposure, the increase of PS amplitude and f-EPSP slope in hippocampal CA1 area of male offspring was lower than that of control group. High concentration of BPA could inhibit Nestin, Cyclin D1, bcl-2 and Rac1 in male offspring rats and the expression of bax and RhoA was promoted by BPA. In summary, our study indicated that BPA exposure during pregnancy and lactation could impair the hippocampal function of male offspring by affecting the growth and apoptosis of hippocampal neurons, which might be due to the abnormal regulation of RhoA and Rac1.

Effects of Bisphenols on Testicular Steroidogenesis

Over the last decades, the adverse effects of human exposure to the so-called "endocrine disruptors" have been a matter of scientific debate and public attention. Bisphenols are synthetic chemicals, widely used in the manufacture of hard plastic products. Bisphenol A (BPA) is one of the best-known environmental toxicants proven to alter the reproductive function in men and to cause other health problems. Consumer concern resulted in "BPA free" products and in the development of bisphenol analogs (BPA-A) to replace BPA in many applications. However, these other bisphenol derivatives seem to have effects similar to those of BPA. Although a number of reviews have summarized the effects of BPA on human reproduction, the purpose of this article is to review the effects of bisphenols on testicular steroidogenesis and to explore their mechanisms of action. Testicular steroidogenesis is a fine-regulated process, and its main product, testosterone (T), has a crucial role in fetal development and maturation and in adulthood for the maintenance of secondary sexual function and spermatogenesis. Contradictory outcomes of both human and animal studies on the effects of BPA on steroid hormone levels may be related to various factors that include study design, dosage of BPA used in in vitro studies, timing and route of exposure, and other confounding factors. We described the main possible molecular target of bisphenols on this complex pathway. We report that Leydig cells (LCs), the steroidogenic testicular component, are highly sensitive to BPA and several mechanisms concur to the functional impairment of these cells.

Effects of bisphenol A on post-embryonic development of the cotton pest Spodoptera littoralis

Endocrine-disrupting chemicals encompass a variety of chemicals that may interfere with the endocrine system and produce negative effects on organisms. Among them, bisphenol A is considered a major pollutant in numerous countries. The harmful effects of BPA on environmental and human health are intensely studied. However, the effects of BPA on terrestrial insects are still poorly investigated, despite that several plants can accumulate BPA in their tissues, leading to potential contamination of herbivorous insects. Here, we used the leafworm Spodoptera littoralis, a polyphagous species, to study BPA effects on post-embryonic development. We studied the effects of BPA ingestion at environmental doses (e.g., 0.01, 0.1, and 1 μg/g of BPA) and high doses (e.g., 25 μg/g) on larval weight and stage duration, pupal length and sex ratio. BPA effects were investigated in more detail during the last larval instar, a crucial period for preparing pupation and metamorphosis, which are under endocrine control. We monitored the haemolymph concentration of ecdysteroids, hormones controlling moult and metamorphosis, as well as the expression levels of several nuclear receptors involved in the ecdysteroid signalling pathway. Our integrative study showed that, upon exposure doses, BPA can induce various effects on the viability, developmental time, growth and sex ratio. These effects were correlated with a delay of the ecdysteroid peak during the last larval instar and a modification of expression of EcR, USP, E75AB, E75D and Br-c. We provide new evidence about the events that occur after BPA exposure in insect contaminated by food ingestion.

Urinary bisphenol analogues concentrations and biomarkers of oxidative DNA and RNA damage in Chinese school children in East China: A repeated measures study

The associations between bisphenol analogues (BPs) exposure and oxidative damage was explored in this 3-year longitudinal study of 275 school children in East China. Nine BPs in first morning urine samples were measured to assess BPs exposure, and 8-hydroxydeoxyguanosine (8-OHdG) and 8-oxo-7,8-dihydroguanosine (8-OHG) were measured as biomarkers of oxidative DNA and RNA damage. Linear mixed model (LMM) was used for repeated measures analysis. School children were mainly exposed to BPA, BPS, BPF, and BPAF (detection frequencies: 97.9%, 42.2%, 13.3%, and 12.8%) with median concentrations of 1.55, 0.355, 0.236 and 0.238 μg g^-1_Cre, respectively. An interquartile range (IQR) increase in urinary BPA was significantly associated with 12.9% (95% CI: 6.1%, 19.6%) increase in 8-OHdG and 19.4% (95% CI: 11.7%, 27.1%) increase in 8-OHG, and for total of BPs (the sum of BPA, BPS, BPF, and BPAF), they were 17.4% (95% CI: 8.9%, 26.0%) for 8-OHdG and 25.9% (95% CI: 16.1%, 35.7%) for 8-OHG, respectively. BPS was positively associated with 8-OHG, but not with 8-OHdG. The study found positive associations of urinary levels of BPA and total BPs with 8-OHdG and 8-OHG and indicated that BPs exposure might cause oxidative RNA damage.

Bisphenol A Analogues in Food and Their Hormonal and Obesogenic Effects: A Review

Bisphenol A (BPA) is the most well-known compound from the bisphenol family. As BPA has recently come under pressure, it is being replaced by compounds very similar in structure, but data on the occurrence of these BPA analogues in food and human matrices are limited. The main objective of this work was to investigate human exposure to BPA and analogues and the associated health effects. We performed a literature review of the available research made in humans, in in vivo and in vitro tests. The findings support the idea that exposure to BPA analogues may have an impact on human health, especially in terms of obesity and other adverse health effects in children.

BPA interferes with StAR-mediated mitochondrial cholesterol transport to induce germline dysfunctions

Bisphenol A is an endocrine disruptor associated with hormone synthesis and reproduction alterations. However, the initiating events underpinning these dysfunctions are still unclear. Here, we address the hypothesis that BPA interferes with the highly evolutionary conserved process of mitochondrial cholesterol transport, a crucial step in steroid hormone biosynthesis, by using the model organism C. elegans. We observed that embryonic lethality and germline apoptosis, hallmarks of BPA's reproductive toxicity in C. elegans, are fully rescued by low exogenous cholesterol supplementation. We also observed that increasing BPA concentrations proportionally reduced mitochondrial cholesterol levels. Mutants for strl-1 (ortholog of StAR), but not C41G7.9 (ortholog of TSPO), show reproductive defects similar to BPA's while BPA exposure in a strl-1 background did not worsen these effects. Finally, cholesterol supplementation rescued these defects for all strl-1 genotype/BPA combinations assessed. Together, these results uncover a novel mechanism underlying BPA's germline toxicity through the alteration of cholesterol transport.

Chronic dietary administration of lower levels of diethyl phthalate induces murine testicular germ cell inflammation and sperm pathologies: Involvement of oxidative stress

The wide occurrence of male infertility is a matter of grave concern. One of the major causes being exposure to endocrine disrupting chemicals (EDCs) many of which are known reproductive toxicants but the molecular mechanisms of action remain much unexplored. Diethyl phthalate (DEP) is ubiquitous in the environment due to its extensive use as plasticizer in myriad consumer products. In the present study, we sought to find out whether chronic DEP exposure affects reproductive function in sexually mature adult male mice. For this, 8-week old Swiss albino mice were treated with DEP (1 mg and 10 mg kg^-1 body weight day^-1) in diet for three months, mirroring the relevant doses of human exposure, and various analyses were carried out in the testicular germ cells and epididymal spermatozoa. We found that altered testicular histoarchitecture was accompanied with disturbed prooxidant: antioxidant balance in the germ cells. Involvement of Nrf2-HO-1 pathway was crucial in this altered cellular redox state. Besides, NFκB mediated inflammatory response was triggered in the germ cells leading to enhanced levels of proinflammatory cytokines. DEP adversely affected sperm count, motility, viability and morphology. Numerous structural anomalies were found in DEP treated mice spermatozoa reflecting decline in sperm function. Our results revealed overactivation of PARP-1 and subsequent cleavage in spermatozoa with induction of apoptosis as a key mechanism in DEP mediated sperm pathology. Given the indiscriminate use of plasticizers and long term low level human exposure, the present study highlights the undesirable male reproductive outcomes following chronic DEP exposure.

Discovery of novel oestrogen receptor α agonists and antagonists by screening a revisited privileged structure moiety for nuclear receptors

Bisphenol A (BPA) is used as an industrial raw material for polycarbonate plastics and epoxy resins; however, various concerns have been reported regarding its status as an endocrine-disrupting chemical. BPA interacts not only with oestrogen receptors (ERs) but constitutive androstane receptor, pregnane X receptor, and oestrogen-related receptor γ (ERRγ); therefore, the bisphenol structure represents a privileged structure for the nuclear-receptor superfamily. Here, we screen 127 BPA-related compounds by competitive-binding assay using [³H]oestradiol and find that 20 compounds bind to ERα with high affinity. We confirm most of these as ERα agonists; however, four compounds, including bisphenol M and bisphenol P act as novel antagonists. These structures harbour three benzene rings in tandem with terminal hydroxy groups at para-positions, with this tandem tri-ring bisphenol structure representing a novel privileged structure for an ERα antagonist. Additionally, we perform an ab initio calculation and develop a new clipping method for halogen bonding or non-covalent interaction using DV-Xα evaluation for biomolecules.

Regulation of TBBPA-induced oxidative stress on mitochondrial apoptosis in L02 cells through the Nrf2 signaling pathway

Tetrabromobisphenol A (TBBPA) is a commonly used brominated flame retardant, which has a wide range of toxic effects on organisms. This study investigated the cytotoxic effects on human hepatocytes (L02 cells) after treated with 0, 5, 10, 20, and 40 μM of TBBPA. Results showed that TBBPA significantly increased intracellular reactive oxygen species (ROS), malondialdehyde (MDA) and the ratio of oxidized/reduced glutathione (GSSG/GSH) dose-dependently. TBBPA also decreased the cell mitochondrial membrane potential (MMP), caused the release of cytochrome C (Cyt C) to cytoplasm and promoted the expression of caspase-9 and caspase-3, and finally increased the level of apoptosis. The ROS inhibitor N-acetyl-L-cysteine (NAC) relieved the oxidative stress responses, and prevented the decrease of MMP and increase of apoptosis. In addition, TBBPA promoted the expression of antioxidant genes related to Nrf2, such as quinone oxidoreductase 1 (NQO1), catalase (CAT), and heme oxygenase 1 (HO-1). Oxidative stress initiated by TBBPA, activated mitochondrial apoptosis and Nrf2 pathway, and increased the degree of apoptosis in L02 cells.

Widespread Occurrence of Bisphenol A in Daily Clothes and Its High Exposure Risk in Humans

Bisphenol A (BPA) is an important endocrine disrupting chemical. Although high levels of BPA in some new clothes have been reported, the occurrence of bisphenol chemicals including BPA in daily clothes is still unknown, and the human exposure to BPA in clothes has not been well assessed. In this study, used/washed clothes were collected from residents' wardrobes and the concentrations of BPA and its analogues were detected. BPA was present in all the used clothes at concentrations ranging from <3.30 to 471 ng/g (median: 34.2 ng/g; mean ± SD: 57.5 ± 93.6 ng/g), while bisphenol S was also detected in 29% of the samples. Although higher average concentration (88.4 ± 289 ng/g) and maximum concentration (1823 ng/g) of BPA were found in the new clothes, the median concentration of BPA in the used clothes (34.2 ng/g) was even higher than that in the new clothes (17.7 ng/g). Cross contamination of BPA during laundering was identified by a simulated laundry experiment, which explained the homogenizing tendency of bisphenol contaminants in the used clothes. An estimated dermal exposure dose of 52.1 ng/kg BW/d was obtained for BPA exposure in children from the highly polluted sweaty clothes (with BPA concentration of 199 ng/g). This indicates a relatively high exposure risk in humans. Compared to other exposure routes, the contribution of dermal exposure dose of BPA from the daily clothes should not be neglected.

Photochemical degradation of BPF, BPS and BPZ in aqueous solution: Identification of transformation products and degradation kinetics

Bisphenols (BPs) are industrial chemicals that are used as monomers in the production of polycarbonate plastics and epoxy resins. These compounds can leach into the aqueous environment, where they can potentially have toxic effects. The aim of this study was to assess the photochemical degradation of three common bisphenols: BPF, BPS and BPZ in aqueous solution and determine their degradation kinetics and characterise their transformation products. Three independent experiments were performed based on: 1) direct photolysis using UV irradiation, 2) cyclodextrin-enhanced photolysis and 3) the photo-Fenton reaction. Analysis was performed using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography coupled to high-resolution quadrupole-time-of-flight mass spectrometry (LC-QTOF-MS). This approach enabled for the first time a comparison between various conditions of photochemical degradation, revealing to be an effective way of removing (>90%) BPF, BPS and BPZ from aqueous samples. In all cases, degradation followed a pseudo-first order kinetic profile, while removal efficiency and formation of transformation products depended on the applied process. The photo-Fenton process resulted in the shortest half-lives (16.1 ̶ 21.7 min) and generated the highest number of transformation products. Overall, in this study we identified 11 novels and eight previously reported TPs.

Comprehensive circRNA/miRNA/mRNA analysis reveals circRNAs protect against toxicity induced by BPA in GC-2 cells

Aim: To identify the circRNAs expression pattern and roles in bisphenol A (BPA) induced germ cell apoptosis. Materials & methods: We performed circRNA/miRNA/mRNA-Seq in 120 μM BPA treated and nontreated GC-2 cells. Bioinformatic analysis, qPCR, apoptosis assays, luciferase report were done in the function analysis. Results: A large number of apoptosis related circRNAs/miRNAs/mRNAs were differentially expressed with competing endogenous RNA network constructed. Interestingly, most investigated upregulated circRNAs, including circDcbld2, circMapk1, circMpp6 and circTbc1d20 showed protective effects in antagonizing BPA toxicity, with the effects individually and synergistically observed. CircMapk1 may take its role by sponging miR-214-3p. Conclusion: circRNAs can play protective roles via sponging miRNAs in toxicity. Some circRNAs may serve as novel targets for BPA toxicity intervention or as biomarkers.

Bisphenol F has different effects on preadipocytes differentiation and weight gain in adult mice as compared with Bisphenol A and S

Bisphenol S (2,2-bisulfone, BPS) and Bisphenol F (2,2-bis [4-hydroxyphenol]methane, BPF) are analogs of Bisphenol A (2,2-bis[4-hydroxyphenyl]propane, BPA), a widely used endocrine disrupting compound present in polycarbonate plastics, thermal receipts and epoxy resins that line food cans. Here we examined effects of BPA, BPS, and BPF in low concentrations on differentiation in murine 3T3-L1 preadipocytes. We also fed adult male mice chow with one of three doses of BPF (0, 0.5, 5, 50 mg/kg chow, or approximately 0.044, 0.44 and 4.4 mg/kg body weight per day) for 12 weeks, collected body weights, food intake, and tested for glucose tolerance. The doses of BPF used produced mean concentrations of 0, 6.2, 43.6, and 561 ng/mL in plasma. In 3T3-L1 cells BPS had the greatest effects, along with BPA, both increased expression of several genes required for preadipocyte differentiation over 12 days in culture. In contrast, BPF decreased expression of several genes late in differentiation. This dichotomy was also reflected in lipid accumulation as BPA and BPS treated cells had elevated lipid concentrations compared to controls or cells treated with BPF. Male mice fed either the highest or lowest concentrations of BPF gained less weight than controls with no effects on glucose levels or glucose tolerance. Plasma levels of BPF reflected doses in food with no overlap between doses. In summary, our results suggest that BPS has a strong potential to be obesogenic while effects of BPF are subtler and potentially in the opposite direction.