The estrogenicity of bisphenol A-related diphenylalkanes with various substituents at the central carbon and the hydroxy groups

Toxic Effects of Bisphenol AF Exposure on the Reproduction and Liver of Female Marine Medaka (Oryzias melastigma)

In recent years, bisphenol AF (BPAF) in aquatic environments has drawn attention to its ecological risks. This study aims to investigate the toxic effects of BPAF (188.33 μg/L) exposure for 30 days on female marine medaka (Oryzias melastigma). On the 10th and 30th day of exposure, the toxicity was evaluated using histological analysis of the liver and ovaries and the transcription levels of genes related to the antioxidant system, immune system, and hypothalamic-pituitary-gonadal (HPG) axis. Findings revealed that (1) BPAF exposure caused vacuolation, karyopyknosis and karyolysis in the liver of marine medaka, and the toxic impact augmented with duration; (2) exposure to BPAF for 10 days facilitated the growth and maturation of primary ova, and this exposure had a comparatively inhibitory effect after 30 days; (3) exposure to BPAF resulted in a biphasic regulation of the transcriptional abundance of genes involved in antioxidant and inflammatory response (e.g., il-8, cat), with an initial up-regulation followed by down-regulation. Additionally, it disrupted the transcriptional pattern of HPG axis-related genes (e.g., 3βhsd, arα). In conclusion, 188.33 μg/L BPAF can alter the expression levels of functionally related genes, impair the structural integrity of marine organisms, and pose a threat to their overall health.

Cell proliferation assay for determination of estrogenic components in food: a systematic review

Due to the widespread use and environmental pollution of estrogenic chemicals, the need for screening tests to detect these compounds is felt more than ever. These compounds lead to cell proliferation. Therefore, studies used cell proliferation to evaluate estrogenic compounds was studied in this systematic review. This systematic review was performed with the keywords; DNA proliferation, cell proliferation, estrogenic component, estrogen, food, bioassay, screening, and detection. After initial screening and full text quality assessment, 16 manuscripts were selected and data were extracted. Four cell lines, MCF-7, MDA-MB-231, Ishikawa, and T47D cells were used in the studies. MCF-7 was more sensitive to estrogenic compounds than other lines. Most of the samples studied were plant compounds and mycotoxins and substances that migrate from packaging to food. This screening test is valid and has similar results as others.

Hormone effects of eighteen bisphenol analogues and their effects on cellular homeostasis and the typical signal pathways

Through the transfer chain of surroundings from feed to the farmed-animals and ultimately the corresponding livestock and poultry products, people are exposed to large amounts of bisphenol analogues (BPs), such as rational emissions from manufacturing plants, feed packaging bags and food packaging contact. Some BPs have been reported to show certain toxicological effects, especially, estrogen and endocrine disrupting effect. With the increasing application of BPs, the problem is becoming more and more serious. We systematically studied the hormonal effects of 18 BPs and their effects on cell homeostasis and classical signaling pathways by using classical E-SCREEN assay, fluorescent probes and western blotting. The results confirmed the estrogen-like effect of 13 BPs and 6 BPs obtained high docking scores (Scores < -9.0) for the three receptors simultaneously with the main interactions of hydrophobic, hydrogen and π-stacking of T-type bonds. BPAP regulates cells via apoptosis and steroid signaling pathway by intracellular ROS and mitochondrial followed the caspase pathway. BPE and BPS were involved in the classical NF-κB and Hippo signaling pathways. All data provides scientific basis for the safety risk assessment of endocrine disrupting and cellular homeostasis evaluation of BPs as chronic environmental pollution.

In silico simulations and molecular descriptors to predict in vitro transactivation potencies of Baikal seal estrogen receptors by environmental contaminants

Baikal seals (Pusa sibirica) are vulnerable to high levels of organic pollutants. Here, we evaluated the transactivation potencies of bisphenols (BPs) and hydroxylated polychlorinated biphenyls (OH-PCBs) via the Baikal seal estrogen receptor α and β (bsERα and bsERβ) using in vitro and in silico approaches. In vitro reporter gene assays showed that most BPs and OH-PCBs exhibited estrogenic activity with bsER sub-type-specific potency. Among the BPs tested, bisphenol AF showed the lowest EC50 for both bsERs. 4'-OH-CB50 and 4'-OH-CB30 showed the lowest EC50 among OH-PCBs tested for bsERα and bsERβ, respectively. 4-((4-Isopropoxyphenyl)-sulfonyl)phenol, 4'-OH-CB72, and 4'-OH-CB121 showed weak bsERα-specific transactivation. Only 4-OH-CB107 did not affect both bsERs. In silico docking simulations revealed the binding affinities of these chemicals to bsERs and partially explained the in vitro results. Using the in silico simulations and molecular descriptors as explanatory variables and the in vitro results as objective variables, the quantitative structure-activity relationship (QSAR) models constructed for classification and regression accurately separated bsER-active compounds from non-active compounds and predicted the in vitro bsERα- and bsERβ-transactivation potencies, respectively. The QSAR models also suggested that chemical polarity, van der Waals surface area, bridging atom structure, position of the phenolic-OH group, and ligand interactions with key residues of the ligand binding pocket are critical variables to account for the bsER transactivation potency of the test compounds. We also succeeded in constructing computational models for predicting in vitro transactivation potencies of mouse ERs in the same manner, demonstrating the applicability of our approach independent of species-specific responses.

Human Exposure to Bisphenols, Parabens, and Benzophenones, and Its Relationship with the Inflammatory Response: A Systematic Review

Bisphenols, parabens (PBs), and benzophenones (BPs) are widely used environmental chemicals that have been linked to several adverse health effects due to their endocrine disrupting properties. However, the cellular pathways through which these chemicals lead to adverse outcomes in humans are still unclear, suggesting some evidence that inflammation might play a key role. Thus, the aim of this study was to summarize the current evidence on the relationship between human exposure to these chemicals and levels of inflammatory biomarkers. A systematic review of peer-reviewed original research studies published up to February 2023 was conducted using the MEDLINE, Web of Science, and Scopus databases. A total of 20 articles met the inclusion/exclusion criteria. Most of the reviewed studies reported significant associations between any of the selected chemicals (mainly bisphenol A) and some pro-inflammatory biomarkers (including C-reactive protein and interleukin 6, among others). Taken together, this systematic review has identified consistent positive associations between human exposure to some chemicals and levels of pro-inflammatory biomarkers, with very few studies exploring the associations between PBs and/or BPs and inflammation. Therefore, a larger number of studies are required to get a better understanding on the mechanisms of action underlying bisphenols, PBs, and BPs and the critical role that inflammation could play.

Biomonitoring bisphenols, parabens, and benzophenones in breast milk from a human milk bank in Southern Spain

BACKGROUND

Human breast milk is considered the optimal source of nutrition for infants. Milk from breast milk banks offers an alternative to infant formulas for vulnerable hospitalized neonates most likely to benefit from exclusive human milk feeding. However, breast milk can also be a source of exposure to environmental contaminants, including endocrine-disrupting chemicals (EDCs).

AIM

To evaluate concentrations of phenolic EDCs, including bisphenols, parabens (PBs), and benzophenones (BPs), in samples from a human milk bank in Granada, Southern Spain and to explore sociodemographic, reproductive, and lifestyle factors related to their concentrations in the milk.

METHODS

Concentrations of three bisphenols [bisphenol A (BPA), bisphenol F (BPF), and bisphenol S (BPS)], four PBs [methyl- (MeP), ethyl- (EtP), propyl- (n-PrP), and butyl-paraben (n-BuP)], and six BPs [BP-1, BP-2, BP-3, BP-6, BP-8, and 4-hydroxy-BP] were determined in milk samples from 83 donors. Information on potential explanatory variables was gathered using the milk bank donor form and an ad hoc questionnaire. Multiple linear and logistic regression models were fitted.

RESULTS

Detectable concentrations were found of at least one of the analyzed compounds in all donor breast milk samples and at least five compounds in one-fifth of them. The most frequently detected compounds were MeP (90.5%), BP-3 (75.0%), EtP (51.2%), n-PrP (46.4%), and BPA (41.7%). Median concentrations ranged between <0.10 ng/mL (n-PrP, n-BuP, BP-1) and 0.59 ng/mL (BP-3). No sample contained detectable concentrations of BPF, BPS, or most BPs (BP-2, BP-6, BP-8, and 4- hydroxy-BP). Breast milk phenol concentrations were associated with parity, the utilization of deodorants, mouthwash, skin care products, and cosmetics, and the intake of nutritional supplements.

CONCLUSIONS

Results reveal the widespread presence of BPA, PBs, and BP-3 in donor breast milk samples, highlighting the need for preventive measures to enhance the benefits of breast milk from milk banks and from breastfeeding women in general.

Bisphenol S induces Agrp expression through GPER1 activation and alters transcription factor expression in immortalized hypothalamic neurons: A mechanism distinct from BPA-induced upregulation

The increasing prevalence of obesity around the world has brought concern upon ubiquitously present obesogenic environmental compounds, such as bisphenol A (BPA). Increasingly tightened regulations on the industrial use of BPA have prompted a transition to a structurally similar alternative, bisphenol S (BPS). BPS displays endocrine-disrupting behaviours similar to those of BPA and increases body weight, food intake and the hypothalamic expression of Agrp in vivo. However, the mechanisms behind this deleterious effect are unclear. Here, we report an increase in the mRNA level of Agrp at 4 h following BPS treatment in immortalized murine hypothalamic cell lines of embryonic and adult origin (mHypoE-41, mHypoA-59). BPS-induced changes in the expression of transcription factors and estrogen receptors that occurred concurrently with Agrp upregulation demonstrated similarities to BPA-induced changes, however, there were also changes that were unique to BPS. Specifically, while Chop, Atf3, Atf4, Atf6, Klf4, and Creb1 were upregulated and Gper1 was downregulated by both BPA and BPS, Esr1 mRNA levels were upregulated and Foxo1 and Stat3 levels remained unchanged by BPS. Finally, inhibition of GPER1 by G15 prevented BPS-mediated Agrp upregulation, independent of Atf3 and Klf4 upregulation. Overall, our results demonstrate the ability of BPS to increase Agrp mRNA expression through GPER1 signaling and to alter transcription factor expression in hypothalamic neurons, further elucidating the endocrine-disrupting potential of this alternative industrial chemical.

Estrogenic Activity of Tetrazole Derivatives Bearing Bisphenol Structures: Computational Studies, Synthesis, and In Vitro Assessment

The classification of bisphenol A (BPA) as an industrial endocrine disruptor has led to a ban of this ubiquitous critical starting material from food and medical applications. Thus, scientists worldwide are researching to develop non-ER binding starting compounds to fulfill unmet market needs. In line with this trending research topic, the current paper highlights the development of tetrazole derivatives bearing a bisphenol structure (TbB) as a novel weak binder or potential inactive to the estrogen receptor (ER) and androgen receptor (AR). The structure and ligand-based approach supported by binding affinity analysis, electrostatic complementarity, ADMET prediction, and in silico studies identified TbBs as privileged substitutes for BPA. Five TbB ligands were successfully synthesized and subjected to biological testing comprising radioligand competitive binding and functional cellular assays. The measured IC₅₀ value for BPA was found to be 0.24 μM, whereas all the inhibitions were less than 15% for the two TbB ligands, 223-2 and 223-3. As these TbB ligands did not meet the established acceptance criteria of 50% inhibition, they are considered as extremely weak binders to ERα. Steric clashes, the desolvation effect, and the increased total polar surface area (TPSA) of TbB ligands in the hydrophobic binding site are hypothesized to be possible reasons for low binding. Modeling studies complemented by bioassays highlight TbB compounds as privileged prospective BPA replacements. However, more research on TbB ligand toxicity is needed to understand and substantiate that the adverse effects on the hormonal system, for example, via metabolic activation, are not elicited.

Concentrations of bisphenols, parabens, and benzophenones in human breast milk: A systematic review and meta-analysis

BACKGROUND

Breast milk is the main source of nutrition for infants but may be responsible for their exposure to environmental chemicals, including endocrine-disrupting chemicals.

AIM

To review available evidence on the presence and concentrations of bisphenols, parabens (PBs), and benzophenones (BPs) in human milk and to explore factors related to exposure levels.

METHODS

A systematic review was carried out using Medline, Web of Science, and Scopus databases, conducting a comprehensive search of peer-reviewed original articles published during the period 2000-2020, including epidemiological and methodological studies. Inclusion criteria were met by 50 studies, which were compiled by calculating weighted detection frequencies and arithmetic mean concentrations of the chemicals. Their risk of bias was assessed using the ROBINS-I checklist.

RESULTS

Among the 50 reviewed studies, concentrations of bisphenols were assessed by 37 (74.0%), PBs by 21 (42.0%), and BPs by 10 (20.0%). Weighted detection frequencies were 63.6% for bisphenol-A (BPA), 27.9-63.4% for PBs, and 39.5% for benzophenone-3 (BP-3). Weighted mean concentrations were 1.4 ng/mL for BPA, 0.2-14.2 ng/mL for PBs, and 24.4 ng/mL for BP-3. Mean concentrations ranged among studies from 0.1 to 3.9 ng/mL for BPA, 0.1 to 1063.6 ng/mL for PBs, and 0.5 to 72.4 ng/mL for BP-3. The highest concentrations of BPA and PBs were reported in samples from Asia (versus America and Europe). Higher BPA and lower methyl-paraben concentrations were observed in samples collected after 2010. Elevated concentrations of these chemicals were associated with socio-demographic and lifestyle factors in eight studies (16.0%). Two epidemiological studies showed moderate/serious risk of bias.

CONCLUSIONS

This systematic review contributes the first overview of the widespread presence and concentrations of bisphenols, PBs, and BPs in human breast milk, revealing geographical and temporal variations. The methodological heterogeneity of published studies underscores the need for well-conducted studies to assess the magnitude of exposure to these chemicals from human milk.

Influence of BPA exposure, measured in saliva, on childhood weight

INTRODUCTION

Endocrine disruptors such as bisphenol A (BPA), BPA glycidyl methacrylate, and other BPA acrylate-based derivatives have been related to type 2 diabetes, the metabolic syndrome, and obesity, among other metabolic disorders. The objective of this study is to examine the influence of BPA exposure by saliva analysis and daily physical activity on the risk of overweight/obesity in schoolchildren from southern Spain.

METHODS

The study included 300 children (53.5% girls) aged 7-10 years. Participants completed a questionnaire with four sections: participant data, including demographic information and life and family habits; semi-quantitative food frequency questionnaire; anthropometric variables; and physical activity variables. All participants underwent dental examination, when the presence of sealants/composites in each tooth and other dental alterations was recorded, and samples of whole saliva were collected for UHPLC-MS/MS analyses.

RESULTS

Risk of overweight/obesity was significantly influenced by body fat composition (OR = 10.77), not walking to and from school (OR = 1.38), lesser energy expenditure in sedentary activities (OR = 12.71), greater energy expenditure in sports (OR =1.62), and exposure to BPA from dental sealants/composites (OR = 1.38; p = 0.058).

DISCUSSION

Further research is warranted on this issue in children, who may be especially vulnerable to the negative health effects of endocrine disruption.

Bisphenol A derivatives act as novel coactivator-binding inhibitors for estrogen receptor β

Bisphenol A and its derivatives are recognized as endocrine disruptors based on their complex effects on estrogen receptor (ER) signaling. While the effects of bisphenol derivatives on ERα have been thoroughly evaluated, how these chemicals affect ERβ signaling is less well understood. Herein, we sought to identify novel ERβ ligands using a radioligand competitive binding assay to screen a chemical library of bisphenol derivatives. Many of the compounds identified showed intriguing dual activities as both ERα agonists and ERβ antagonists. Docking simulations of these compounds and ERβ suggested that they bound not only to the canonical binding site of ERβ but also to the coactivator binding site located on the surface of the receptor, suggesting that they act as coactivator-binding inhibitors (CBIs). Receptor-ligand binding experiments using WT and mutated ERβ support the presence of a second ligand-interaction position at the coactivator-binding site in ERβ, and direct binding experiments of ERβ and a coactivator peptide confirmed that these compounds act as CBIs. Our study is the first to propose that bisphenol derivatives act as CBIs, presenting critical insight for the future development of ER signaling-based drugs and their potential to function as endocrine disruptors.

Occurrence, Profiles and Ecological Risk of Bisphenol Analogues in a Municipal Sewage Treatment Plant

Due to the strict control on bisphenol A (BPA) in many countries, bisphenol analogues (BPs) are being widely used as alternative materials to manufacture epoxy resins and polycarbonate plastics, resulting in their occurrence in sewage treatment plants (STPs). In this study, the occurrence and distribution of 7 BPs in a large-scale STP in Beijing China was investigated. Wastewater samples were collected from the influents and effluents of each processing unit, and extracted by solid-phase extraction. Target compounds were quantified by ultra-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The total concentrations of seven BPs (ΣBPs) were 400.42 ± 48.12 ng/L in the raw sewage, 438.60 ± 46.50 ng/L in the primary effluent, 17.21 ± 13.12 ng/L in the secondary effluent, and 11.33 ± 4.84 ng/L in the tertiary effluent, respectively. Bisphenol S (BPS) and BPA were the predominant congener in raw sewage with an overall contribution of 29.32% and 70.22% to the ΣBPs, indicating that there was a large amount of BPS and BPA consumption in the study area. During a one-week sampling period, ΣBPs changed slightly at the same sampling site. It was found that high removal efficiencies were achieved for BPs in anoxic and oxic secondary clarifier treatment units, suggesting that biodegradation and sorption played major roles in BPs elimination in the STP. After tertiary treatment, all BPs except BPA were completely removed, suggesting the necessity to investigate the fate and toxicity of BPA in the aquatic environment.

Toxicity of bisphenol analogues on the reproductive, nervous, and immune systems, and their relationships to gut microbiome and metabolism: insights from a multi-species comparison

Bisphenols are common chemicals found in plastics and epoxy resins. Over the past decades, many studies have shown that bisphenol A (BPA) is a potential endocrine-disrupting chemical that may cause multisystem toxicity. However, the relative safety of BPA analogues is a controversial subject. Herein, we conducted a review of the reproductive toxicity, neurotoxicity, immunotoxicity, metabolic toxicity and gut microbiome toxicity of the BPA analogues in various species, including Caenorhabditis elegans, zebrafish, turtles, sheep, rodents, and humans. In addition, the mechanisms of action were discussed with focus on bisphenol S and bisphenol F. It was found that these BPA analogues exert their toxic effects on different organs and systems through various mechanisms including epigenetic modifications and effects on cell signaling pathways, microbiome, and metabolome in different species. More research is needed to study the relative toxicity of the lesser-known BPA analogues compared to BPA, both systemically and organ specifically, and to better define the underlying mechanisms of action, in particular, the potentials of disrupting microbiome and metabolism.

Serum bisphenol A analogues in women diagnosed with the polycystic ovary syndrome - is there an association?

Due to the endocrine disrupting effects of bisphenol A (BPA) several governmental authorities have banned its use and the manufacturers had to find alternative substances with similar chemical properties. This led to the increase in the use of so-called BPA analogues, which however also turn out to possess mild estrogenic and ani-androgenic properties and thus, may cause fertility problems and sex-hormone dependent endocrinopathies. The aim of this study was to evaluate the potential association between the exposure to BPA and its two analogues: BPS and BPF, with the diagnosis of the polycystic ovary syndrome (PCOS), which remains the most common female endocrinopathy. Serum concentrations of BPA, BPS and BPF were measured using high performance liquid chromatography method with tandem mass spectrometry (HPLC-MS/MS) among 199 women with PCOS and 158 control subjects. In women with PCOS serum BPS concentrations were significantly higher compared to the control subjects (geometric mean [95% CI]: 0.14 ng/mL [0.10; 1.17] vs. 0.08 ng/mL [0.06; 0.09], P = 0.023). Serum BPA and BPF concentrations did not differ between the studied groups. There was however a negative correlation between serum BPA and HOMA-IR (r = - 0.233, P = 0.001) and TST (r = - 0.203, P = 0.006) in women with PCOS. No correlations were found between the serum BPs and other metabolic parameters such as serum lipids, insulin, DHEA-S, androstenedione and FAI. When studying the association between serum BPA analogues and PCOS it turned out that women whose serum BPS concentrations were in the first tertile were more likely to be diagnosed with this endocrinopathy (OR [95% CI]: 1.21 [1.04; 3.46], P = 0.017). This association was also statistically significant when adjusted for age, education, BMI, smoking, income, and alcohol consumption (adjusted OR [95% CI]: 1.12 [1.03; 3.71], P = 0.029). These results point to the potential association between the exposure to BPS and the diagnosis of PCOS. The role of BPA is not clear and warrants further studies.

Human phase I in vitro liver metabolism of two bisphenolic diglycidyl ethers BADGE and BFDGE

Root canal sealers are commonly used to endodontically treat teeth with periapical infections. Some root canal sealers based on epoxy resin contain bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE). The presence of these chemicals is of concern due to the close contact to the blood stream at the apex and the long setting times of up to 24 h. These chemicals, or any of their degradation products or metabolites, can then exert their toxic effects before being excreted. This study aimed to identify the phase I in vitro biotransformation products of BADGE and BFDGE using human liver microsomes. During incubation with microsomal fractions, the epoxides were rapidly hydrolysed in a NADPH independent manner resulting in the formation of BADGE.2H₂O and BFDGE.2H₂O. Further, oxidative reactions, such as hydroxylation and carboxylation, generated other BADGE metabolites, such as BADGE.2H₂O-OH and BADGE.H₂O.COOH, respectively. For BFDGE, further oxidation of BFDGE.2H₂O led to the newly reported carboxylic acid, BFDGE.H₂O.COOH. In total, three specific metabolites have been identified which can serve in future human biomonitoring studies of BADGE and BFDGE.

The estrogenic proliferative effects of two alkylphenols and a preliminary mechanism exploration in MCF-7 breast cancer cells

Bisphenol A (BPA) and 4-cumylphenol (4-CP), as estrogen-like chemicals, are ubiquitous in the environment media and associated with the occurrence and development of hormone-dependent tumors. However, the combinatorial effects of these two structurally similar alkylphenols are not well informed. In the present study, the classic breast cancer cell line MCF-7 was used as in vitro model to estimate the estrogenic proliferative effects of BPA and 4-CP. MTT assay, reactive oxygen species, cell apoptosis, cell cycle, and real-time fluorescent quantitative Step One Plus Real-time PCR System (Applied Biosystems, CA, USA) were applied to explore their proliferative mechanisms. MTT results showed that both BPA and 4-CP ranging from 10^-9 to 10^-5 M stimulated cell proliferation in a nonmonotonic dose-response manner. Along with the proliferative effects, cell cycle was progressed from G0/G1 to S and G2/M phase. Meanwhile, the expression levels of ERα, pS2, and Bcl-2 mRNA were also upregulated. In contrast, 4-CP and BPA at high dose (10^-4 M) obviously displayed antiproliferative effects in MCF-7 cells via inducing cell apoptosis and blocking cell cycle in G0/G1 phase. As expected, the relative expression levels of ERα, pS2, and Bcl-2 mRNA were decreased, whereas Bax mRNA was increased. Interestingly, the proliferative or antiproliferative effects of 4-CP were higher than that of BPA. Moreover, coexposure of lower concentrations BPA and 4-CP significantly induced cell proliferation in a synergistic manner. These findings indicated that the potential environmental risks of coexposure of BPA and 4-CP were greater than either of them.

Association of Urinary Levels of Bisphenols A, F, and S with Endometriosis Risk: Preliminary Results of the EndEA Study

Aim: The aim of this study was to explore associations of urinary concentrations of bisphenols A (BPA), S (BPS), and F (BPF) and of thiobarbituric acid reactive substances (TBARS) with the risk of endometriosis in women of childbearing age. Methods: This case-control study enrolled 124 women between January 2018 and July 2019: 35 women with endometriosis (cases) and 89 women without endometriosis undergoing abdominal surgery for other reasons (controls). Endometriosis was diagnosed (cases) or ruled out (controls) by laparoscopic inspection of the pelvis and the biopsy of suspected lesions (histological diagnosis). Fasting urine samples were collected before surgery to determine concentrations of BPA, BPS, BPF, and TBARS. Associations of bisphenol and TBARS concentrations with endometriosis risk were explored with multivariate logistic and linear regression analyses. Results: After adjustment for urinary creatinine, age, BMI, parity, and residence, endometriosis risk was increased with each 1 log unit of BPA [OR 1.5; 95%CI 1.0-2.3] and Σbisphenols [OR 1.5; 95%CI 0.9-2.3] but was not associated with the presence of BPS and BPF. Classification of the women by tertiles of exposure revealed statistically significant associations between endometriosis risk and the second tertile of exposure to BPA [OR 3.7; 95%CI 1.3-10.3] and Σbisphenols [OR 5.4; 95%CI 1.9-15.6]. In addition, TBARS concentrations showed a close-to-significant relationship with increased endometriosis risk [OR 1.6; 95%CI 1.0-2.8], and classification by TBARS concentration tertile revealed that the association between endometriosis risk and concentrations of BPA [OR 2.0; 95%CI 1.0-4.1] and Σbisphenols [OR 2.2; 95%CI 1.0-4.6] was only statistically significant for women in the highest TBARS tertile (>4.23 μM). Conclusion: Exposure to bisphenols may increase the risk of endometriosis, and oxidative stress may play a crucial role in this association. Further studies are warranted to verify these findings.

Deciphering Adverse Outcome Pathway Network Linked to Bisphenol F Using Text Mining and Systems Toxicology Approaches

Bisphenol F (BPF) is one of several Bisphenol A (BPA) substituents that is increasingly used in manufacturing industry leading to detectable human exposure. Whereas a large number of studies have been devoted to decipher BPA effects, much less is known about its substituents. To support decision making on BPF's safety, we have developed a new computational approach to rapidly explore the available data on its toxicological effects, combining text mining and integrative systems biology, and aiming at connecting BPF to adverse outcome pathways (AOPs). We first extracted from different databases BPF-protein associations that were expanded to protein complexes using protein-protein interaction datasets. Over-representation analysis of the protein complexes allowed to identify the most relevant biological pathways putatively targeted by BPF. Then, automatic screening of scientific abstracts from literature using the text mining tool, AOP-helpFinder, combined with data integration from various sources (AOP-wiki, CompTox, etc.) and manual curation allowed us to link BPF to AOP events. Finally, we combined all the information gathered through those analyses and built a comprehensive complex framework linking BPF to an AOP network including, as adverse outcomes, various types of cancers such as breast and thyroid malignancies. These results which integrate different types of data can support regulatory assessment of the BPA substituent, BPF, and trigger new epidemiological and experimental studies.

Presence of Bisphenol A and Parabens in a Neonatal Intensive Care Unit: An Exploratory Study of Potential Sources of Exposure

BACKGROUND

Newborns in neonatal intensive care units (NICUs) are in contact with a variety of medical products whose production might include synthetic chemicals with hormonal activity.

OBJECTIVES

Our aim was to assess the content of bisphenol A (BPA) and parabens (PBs) and the hormone-like activities of a subset of medical products commonly used in NICUs in prolonged intimate contact with NICU newborns.

METHODS

Fifty-two NICU items were analyzed, determining the concentrations of BPA and PBs [methyl- (MeP), ethyl- (EtP), propyl- (PrP), and butylparaben (BuP)] and using the E-Screen and PALM-luciferase assays to measure the in vitro (anti-)estrogenic and (anti-)androgenic activity, respectively, of the extracts. Items found to have elevated BPA/PB content or hormone-like activities were further extracted using leaching methodologies.

RESULTS

BPA was found in three-fifths and PBs in four-fifths of tested NICU items, and ∼25% and ∼10% of extracts evidenced estrogenic and anti-androgenic activity, respectively. The highest BPA content was found in the three-way stopcock (>7.000 ng/g), followed by patterned transparent film dressing, gastro-duodenal feeding tubes, sterile gloves, single-lumen umbilical catheters, and intravenous (IV) infusion extension sets (concentrations ranged from 100 to 700 ng/g BPA). A total PB concentration (∑PBs) >100 ng/g was observed in several items, including light therapy protection glasses, patterned transparent film dressing, winged IV catheters, IV infusion extension sets, and textile tape. The highest estrogenic activity [>450 pM estradiol equivalent (E2eq)] was found in small dummy nipples, three-way stopcocks, and patterned transparent film dressing and the highest anti-androgenic activity [>5 mM procymidone equivalent units per gram (Proceq/g)] in small dummy nipples and three-way stopcocks.

DISCUSSION

According to these findings, neonates might be exposed to multiple sources of BPA and PBs in NICUs via inhalation, dermal, oral, and IV/parenteral routes. There is a need to address the future health implications for these extremely vulnerable patients and to adopt precautionary preventive measures as a matter of urgency. https://doi.org/10.1289/EHP5564.

Evidence for Bisphenol B Endocrine Properties: Scientific and Regulatory Perspectives

BACKGROUND

The substitution of bisphenol A (BPA) by bisphenol B (BPB), a very close structural analog, stresses the need to assess its potential endocrine properties.

OBJECTIVE

This analysis aimed to investigate whether BPB has endocrine disruptive properties in humans and in wildlife as defined by the World Health Organization (WHO) definition used in the regulatory field, that is, a) adverse effects, b) endocrine activity, and c) plausible mechanistic links between the observed endocrine activity and adverse effects.

METHODS

We conducted a systematic review to identify BPB adverse effects and endocrine activities by focusing on animal models and in vitro mechanistic studies. The results were grouped by modality (estrogenic, androgenic, thyroid hormone, steroidogenesis-related, or other endocrine activities). After critical analysis of results, lines of evidence were built using a weight-of-evidence approach to establish a biologically plausible link. In addition, the ratio of BPA to BPB potency was reported from studies investigating both bisphenols.

RESULTS

Among the 36 articles included in the analysis, 3 subchronic studies consistently reported effects of BPB on reproductive function. In rats, the 28-d and 48-week studies showed alteration of spermatogenesis associated with a lower height of the seminiferous tubules, the alteration of several sperm parameters, and a weight loss for the testis, epididymis, and seminal vesicles. In zebrafish, the results of a 21-d reproductive study demonstrated that exposed fish had a lower egg production and a lower hatching rate and viability. The in vitro and in vivo mechanistic data consistently demonstrated BPB's capacity to decrease testosterone production and to exert an estrogenic-like activity similar to or greater than BPA's, both pathways being potentially responsible for spermatogenesis impairment in rats and fish.

CONCLUSION

The available in vivo, ex vivo, and in vitro data, although limited, coherently indicates that BPB meets the WHO definition of an endocrine disrupting chemical currently used in a regulatory context. https://doi.org/10.1289/EHP5200.

Evaluation of the Potential Toxicity of Effluents from the Textile Industry before and after Treatment

The textile industry has an important role in the economic development of several countries; however, it consumes large amounts of water and generates huge quantities of wastewater. These effluents are of great environmental concern due to their complex chemical content, known by their toxicity and low biodegradability, which can cause harmful effects to the aquatic environment. In the present study, bioassays with aquatic species were employed to evaluate the toxicity of effluent samples collected before and after the treatments performed by the textile company. The toxic effects were investigated using four organisms, namely Aliivibrio fischeri, Raphidocelis subcapitata, Daphnia magna and Lemna minor, to represent different trophic levels. The ecotoxicological data confirmed that the raw textile effluent was very toxic, with A. fischeri being the most sensitive organism. While the toxicity of the effluent collected after the treatment performed by the textile company was clearly reduced, we still recorded sublethal toxicity to D. magna. These results highlight the importance of the bioassays for continuous monitoring of the toxicity of the treated effluents to prevent adverse effects on the environment. Further, results suggest that ecotoxicological data should be required in parallel with chemical data to better evaluate the safety of environmental discharges of wastewaters.

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.

Receptor-binding affinities of bisphenol A and its next-generation analogs for human nuclear receptors

An endocrine-disrupting chemical Bisphenol A (BPA) binds specifically to a nuclear receptor (NR) named ERRγ. Although the importance of receptor-binding evaluation for human NRs is often stressed, the binding characteristics of so-called next-generation (NextGen) bisphenol compounds are still poorly understood. The ultimate objective of this investigation was to evaluate BPA and its NextGen analogs for their abilities to bind to 21 human NRs, the greatest members of NRs for which tritium-labeled specific ligands were available. After establishing the detailed assay conditions for each NR, the receptor binding affinities of total 11 bisphenols were evaluated in competitive binding assays. The results clearly revealed that BPA and the NextGen bisphenols of BPAF, BPAP, BPB, BPC, BPE, and BPZ were highly potent against one or more of NRs such as CAR, ERα, ERβ, ERRγ, and GR, with IC₅₀ values of 3.3-73 nM. These bisphenols were suggested strongly to be disruptive to these NRs. BPM and BPP also appeared to be disruptive, but less potently. BPF exhibited only weak effects and only against estrogen-related NRs. Surprisingly, most doubtful bisphenol BPS was supposed not to be disruptive. The NRs to which BPA and NextGen bisphenols did not bind were RARα, RARβ, RARγ, and VDR. PPARγ, RORα, RORβ, RORγ, RXRα, RXRβ, and RXRγ, exhibited very weak interaction with these bisphenols. The ten remaining NRs, namely, ERRγ, ERβ, ERα, CAR, GR, PXR, PR, AR, LXRβ, and LXRα, showed distinctly strong binding to some bisphenols in this order, being likely to have consequential endocrine-disruption effects.

Endocrine Disruptors: A Critical Review of In Vitro and In Vivo Testing Strategies for Assessing Their Toxic Hazard to Humans

Currently, there is much concern that a wide range of both synthetic and naturally occurring environmental chemicals can act as endocrine disruptors (EDs), and can adversely affect humans and wildlife. Many in vivo and in vitro tests have been proposed for screening EDs, and several regulatory agencies, including the US Environmental Protection Agency (EPA), have recommended tier-testing schemes. Unfortunately, most of the proposed toxicity tests have substantial problems, including non-specificity and lack of reproducibility. There is also uncertainty concerning their relevance for generating useful hazard data for risk assessment purposes, in view of the diversity of the possible ED mechanisms of action (for example, receptor binding, steroidogenesis and modulation of the homeostatic processes which regulate endogenous responses to hormones). Moreover, most of the suggested test methods have yet to be validated according to internationally accepted criteria, although the OECD and the US EPA have defined tests for validation, and an interlaboratory “prevalidation” exercise has been initiated by the OECD. All this is compounded by the lack of information regarding human exposure levels to EDs, and a lack of direct evidence for a causal link between exposure and the development of adverse human health effects. In addition, the regulatory testing of EDs has important negative implications for animal welfare, as some of the proposed in vivo tests require large group sizes of animals and stressful procedures. From a detailed analysis of the available published literature, it is concluded that it is impossible to assess the relative values of currently available in vitro and in vivo toxicity tests for EDs, or to recommend any test or test battery. Any plans for the widespread testing of EDs are therefore premature and might be unnecessary, at least for detecting possible human effects. Several recommendations are made for rectifying this unsatisfactory situation, including the postponement of screening programmes pending: a) more information on human exposure; b) further details of the mechanisms of action of EDs; and c) the development of improved tests, followed by their proper scientific validation.

Sustainable bio-based furan epoxy resin with flame retardancy

A sugar-based bis-furan diepoxide (OmbFdE) was developed which imparted epoxy resins with excellent fire retardancy.

Isoamericanoic Acid B from Acer tegmentosum as a Potential Phytoestrogen

Phytoestrogens derived from plants have attracted the attention of the general public and the medical community due to their potentially beneficial role in relieving menopausal symptoms. The deciduous tree Acer tegmentosum Maxim (Aceraceae) has long been utilized in Korean folk medicine to alleviate many physiological disorders, including abscesses, surgical bleeding, and liver diseases. In order to explore structurally and/or biologically new constituents from Korean medicinal plants, a comprehensive phytochemical study was carried out on the bark of A. tegmentosum. One new phenolic compound with a 1,4-benzodioxane scaffold, isoamericanoic acid B (1), as well as with nine known phenolic compounds (2–10), were successfully isolated from the aqueous extracts of the bark of A. tegmentosum. A detailed analysis using 1D and 2D NMR spectroscopy, electronic circular dichroism (ECD) spectral data, and LC/MS afforded the unambiguous structural determination of all isolated compounds, including the new compound 1. In addition, compounds 2, 4, 5, and 9 were isolated and identified from the bark of A. tegmentosum for the first time. All isolated compounds were tested for their estrogenic activities using an MCF-7 BUS cell proliferation assay, which revealed that compounds 1, 2, and 10 showed moderate estrogenic activity. To study the mechanism of this estrogenic effect, a docking simulation of compound 1, which showed the best estrogenic activity, was conducted with estrogen receptor (ER) -α and ER-β, which revealed that it interacts with the key residues of ER-α and ER-β. In addition, compound 1 had slightly higher affinity for ER-β than ER-α in the calculated Gibbs free energy for 1:ER-α and 1:ER-β. Thus, the present experimental evidence demonstrated that active compound 1 from A. tegmentosum could be a promising phytoestrogen for the development of natural estrogen supplements.

Environmental phenols and parabens in adipose tissue from hospitalized adults in Southern Spain

Urinary concentrations of non-persistent environmental pollutants (npEPs) are widely assessed in biomonitoring studies under the assumption that they are metabolised and eliminated in urine. However, some of these chemicals are moderately lipophilic, and their presence in other biological matrices should also be evaluated to estimate mid/long-term exposure to npEPs and its impact on human health. The present study aims to explore concentrations and potential determinants of npEPs in adipose tissue from a hospital-based adult cohort (GraMo cohort, Southern Spain). Concentrations of bisphenol-A (BPA), benzophenone-3 (BP-3), triclosan (TCS), three chlorophenols (2,4-DCP, 2,5-DCP and 2,4,5-TCP) and two phenylphenols (2-PP and 4-PP), triclocarban (TCCB) and parabens [methyl- (MeP), ethyl- (EtP), propyl- (n-PrP and i-PrP), butyl- (n-BuP and i-BuP) and benzyl-paraben (BzP)] were analysed in adipose tissue samples from a subcohort of 144 participants. Spearman correlation tests were performed, followed by stepwise multivariable linear regression analyses to assess determinants of the exposure. Detection frequencies and median concentrations were: BPA (86.8%, 0.54 ng/g tissue), BP-3 (79.2%, 0.60 ng/g tissue), TCS (45.8%, <LOD), 2-PP (18.8%, <LOD), MeP (100.0%, 0.40 ng/g tissue), EtP (20.1%, <LOD) and n-PrP (54.2%, 0.06 ng/g tissue). The remaining npEPs were detected in <10% of the samples. BPA, MeP, EtP and n-PrP levels were significantly and positively correlated, while BP-3 showed a positive correlation with TCS and 2-PP. Older participants showed higher concentrations of TCS and MeP, while BMI was inversely associated with most of the analysed compounds and perceived recent weight loss was inversely associated with 2-PP. Female participants and residents of rural areas had increased BP-3 concentrations. npEP concentrations were positively associated with the consumption of fatty food but negatively associated with the consumption of vegetables and fruit. This study reveals the widespread presence of numerous npEPs in adipose tissue from adults in southern Spain, suggesting a generalized distribution of these environmental compounds in fatty tissues. In these adults, many of the determinants of npEP concentrations in adipose tissue were similar to those of more lipophilic and persistent compounds.

Bisphenol A and Its Derivatives Induce Degradation of HIF-1alpha via the Lysosomal Pathway in Human Hepatocarcinoma Cell Line, Hep3B

Bisphenol A (BPA, 2,2-bis(4-hydroxyphenyl)propane), one of the phenolic compounds widely used in the manufacture of plastic and epoxy resins, is known as an endocrine disruptor. In a previous study, we found that BPA induced hypoxia inducible factor-1alpha (HIF-1alpha) degradation by dissociation from heat shock protein 90 (Hsp90). In this study, to investigate the structural requirements for degradation of HIF-1alpha, we estimated the effect of BPA derivatives (BPE, BPF, BPB, Dimethyl butylidene diphenol (DMBDP), Ethyl hexylidene diphenol (EHDP), Bishydroxyphenyl cyclohexane (BHCH), and Methyl benzylidene bisphenol (MBBP)) on HIF-1alpha protein degradation, using human hepatocarcinoma cell line, Hep3B. BPB, DMBDP, BHCH, and MBBP decreased HIF-1alpha protein levels more efficiently than BPA, but BPE, BPF, and EHDP did not affect HIF-1alpha protein levels. BPA degraded HIF-1alpha even in the presence of MG132, a proteasome inhibitor. In this study, we found that ammonium chloride (NH₄Cl), a lysosomal enzyme inhibitor, efficiently restored the decrease in HIF-1alpha protein levels by BPA. Recent studies indicated that HIF-1alpha is degraded by the lysosomal pathway as well as the proteasomal pathway. Therefore, we investigated the levels of heat shock cognate 70 kDa protein (HSC70) protein after treatment with BPA. We found that BPA induced HSC70 protein and overexpression of HSC70 enhanced HIF-1alpha degradation in Hep3B cells. These results suggested that BPA causes the degradation of HIF-1alpha by induction of HSC70, leading lysosomal degradation of HIF-1alpha.

Evaluation of Prenatal Exposure to Bisphenol Analogues on Development and Long-Term Health of the Mammary Gland in Female Mice

BACKGROUND

Continued efforts to phase out bisphenol A (BPA) from consumer products have been met with the challenges of finding safer alternatives.

OBJECTIVES

This study aimed to determine whether early-life exposure to BPA and its related analogues, bisphenol AF (BPAF) and bisphenol S (BPS), could affect female pubertal mammary gland development and long-term mammary health in mice.

METHODS

Timed pregnant CD-1 mice were exposed to vehicle, BPA (0.5, 5, 50 mg/kg), BPAF (0.05, 0.5, 5 mg/kg), or BPS (0.05, 0.5, 5 mg/kg) via oral gavage between gestation days 10–17. Mammary glands were collected from resulting female offspring at postnatal day (PND) 20, 28, 35, and 56, and at 3, 8, and 14 months for whole mount, histopathological evaluation, and quantitative real-time polymerase chain reaction (qPCR); serum steroid concentrations were also measured at these time points.

RESULTS

In the bisphenol-exposed mice, accelerated mammary gland development was evident during early puberty and persisted into adulthood. By late adulthood, mammary glands from bisphenol-exposed female offspring exhibited adverse morphology in comparison with controls; most prominent were undifferentiated duct ends, significantly more lobuloalveolar hyperplasia and perivascular inflammation, and various tumors, including adenocarcinomas. Effects were especially prominent in the BPAF 5 mg/kg and BPS 0.5 mg/kg groups. Serum steroid concentrations and mammary mRNA levels of Esr1, Pgr, Ar, and Gper1 were similar to controls.

CONCLUSIONS

These data demonstrate that prenatal exposure of mice to BPAF or BPS induced precocious development of the mammary gland, and that siblings were significantly more susceptible to spontaneous preneoplastic epithelial lesions and inflammation, with an incidence greater than that observed in vehicle- and BPA-exposed animals. https://doi.org/10.1289/EHP3189.

Mechanism of bisphenol AF-induced progesterone inhibition in human chorionic gonadotrophin-stimulated mouse Leydig tumor cell line (mLTC-1) cells

Bisphenol AF (BPAF) has been shown to inhibit testicular steroidogenesis in male rats. However, the precise mechanisms related to the toxic effects of BPAF on reproduction remain poorly understood. In the present study, a mouse Leydig tumor cell line (mLTC-1) was used as a model to investigate the mechanism of steroidogenic inhibition and to identify the molecular target of BPAF. Levels of progesterone and the concentration of cyclic adenosine monophosphate (cAMP) in cells exposed to BPAF were detected, and expression of key genes and proteins in steroid biosynthesis was assessed. The results showed that BPAF exposure decreased human chorionic gonadotrophin (hCG)-stimulated progesterone production in a dose-dependent manner. The 24-h IC₅₀ (half maximal inhibitory concentration) value for BPAF regarding progesterone production was 70.2 µM. A dramatic decrease in cellular cAMP concentration was also observed. Furthermore, BPAF exposure inhibited expression of genes and proteins involved in cholesterol transport and progesterone biosynthesis. Conversely, the protein levels of steroidogenic acute regulatory protein (StAR) were not altered, and those of progesterone were still decreased upon 22R-hydroxycholesterol treatment of cells exposed to higher doses of BPAF. Together, these data indicate that BPAF exposure inhibits progesterone secretion in hCG-stimulated mLTC-1 cells by reducing expression of scavenger receptor class B type I (SR-B1) and cytochrome P450 (P450scc) due to the adverse effects of cAMP. However, StAR might not be the molecular target in this process.

Detection of bisphenol A, cumylphenol and parabens in surface waters of Greater Poland Voivodeship

Amounts of bisphenol A (BPA), 4-cumylphenol (CP) and 5 parabens - methylparaben (MP), ethylparaben (EP), propylparaben (PP), butylparaben (BP) and benzylparaben (BzP) in Greater Poland Voivodeship's surface waters are reported. The water samples were collected from selected 15 locations in 2015-2016 at seven different time points: in March, June, August, and October 2015 and March, June, and September 2016. MP was found in every tested sample with typical concentration at several dozen nanograms per liter and the highest level almost 1600 ng L^-1 in a sample collected from the Warta River in October 2015. The other four parabens were determined at considerably lower concentrations than MP at levels not exceeding 100 ng L^-1 with PP found at the highest and BzP at the lowest levels. BPA was determined at similar concentration level to parabens - between 5 ng L^-1 and 95 ng L^-1 and CP was found only in a limited number of samples. Noticeable seasonal changes of paraben concentrations were found showing that for these compounds the pollutant release factor dominates both the biodegradation factor and the water volume factor. These seasonal changes were not observed for BPA and CP. Out of all determined parabens only MP was found at considerably higher concentrations than BPA. However, MP's endocrine properties are much lower than those of BPA posing a lower environmental impact potential than BPA. Influence of other (more endocrine disrupting) parabens is also relatively weak in comparison to BPA due to their considerably lower concentrations in the environment.

Effects of maternal exposure to bisphenol AF on emotional behaviors in adolescent mice offspring

Exposure to bisphenol A (BPA), one kind of environmental endocrine disruptors (EEDs), exerted significantly detrimental effects on neuro-endocrinological system and related disorders, such as memory dysfunction and depression. Bisphenol AF (BPAF),a newly introduced chemical structurally related to BPA, is used extensively. BPAF has stronger estrogenic activities than BPA. However, the potential neurotoxicological effects of BPAF are still elusive. The present study aimed to investigate the potential effects of maternal BPAF exposure during pregnancy on emotional behaviors of adolescent mice offspring. In male adolescent offspring, maternal exposure to BPAF (0.4, 4.0 mg kg^-1, intragastrically administration) induced significant anxiety- and depressive-like behaviors, assessed by open field test (OFT), novelty-suppressed feeding test (NSF), sucrose preference test (SPT), tail suspension test (TST) and forced swimming test (FST). In female adolescent offspring, BPAF exposure at 0.4 mg kg^-1 dose reduced the latency to feeding in the NSF test, while increased the floating time in the FST. Maternal BPAF exposure decreased the recognition index in the long term memory (LTM) test in both sexes, while only decreased the freezing time of male offspring in the contextual fear conditioning (CFC) task. These results indicate that maternal exposure to BPAF significantly affect emotion-related behaviors in adolescent mice offspring, and the male offspring with a higher probability to develop symptoms of anxiety and depression and to suffer memory impairment after maternal exposure to BPAF.

Bio-Based Aromatic Epoxy Monomers for Thermoset Materials

The synthesis of polymers from renewable resources is a burning issue that is actively investigated. Polyepoxide networks constitute a major class of thermosetting polymers and are extensively used as coatings, electronic materials, adhesives. Owing to their outstanding mechanical and electrical properties, chemical resistance, adhesion, and minimal shrinkage after curing, they are used in structural applications as well. Most of these thermosets are industrially manufactured from bisphenol A (BPA), a substance that was initially synthesized as a chemical estrogen. The awareness on BPA toxicity combined with the limited availability and volatile cost of fossil resources and the non-recyclability of thermosets implies necessary changes in the field of epoxy networks. Thus, substitution of BPA has witnessed an increasing number of studies both from the academic and industrial sides. This review proposes to give an overview of the reported aromatic multifunctional epoxide building blocks synthesized from biomass or from molecules that could be obtained from transformed biomass. After a reminder of the main glycidylation routes and mechanisms and the recent knowledge on BPA toxicity and legal issues, this review will provide a brief description of the main natural sources of aromatic molecules. The different epoxy prepolymers will then be organized from simple, mono-aromatic di-epoxy, to mono-aromatic poly-epoxy, to di-aromatic di-epoxy compounds, and finally to derivatives possessing numerous aromatic rings and epoxy groups.

High-Content Analysis Provides Mechanistic Insights into the Testicular Toxicity of Bisphenol A and Selected Analogues in Mouse Spermatogonial Cells

Bisphenol A (BPA), an endocrine-disrupting compound, was found to be a testicular toxicant in animal models. Bisphenol S (BPS), bisphenol AF (BPAF), and tetrabromobisphenol A (TBBPA) were recently introduced to the market as alternatives to BPA. However, toxicological data of these compounds in the male reproductive system are still limited so far. This study developed and validated an automated multi-parametric high-content analysis (HCA) using the C18-4 spermatogonial cell line as a model. We applied these validated HCA, including nuclear morphology, DNA content, cell cycle progression, DNA synthesis, cytoskeleton integrity, and DNA damage responses, to characterize and compare the testicular toxicities of BPA and 3 selected commercial available BPA analogues, BPS, BPAF, and TBBPA. HCA revealed BPAF and TBBPA exhibited higher spermatogonial toxicities as compared with BPA and BPS, including dose- and time-dependent alterations in nuclear morphology, cell cycle, DNA damage responses, and perturbation of the cytoskeleton. Our results demonstrated that this specific culture model together with HCA can be utilized for quantitative screening and discriminating of chemical-specific testicular toxicity in spermatogonial cells. It also provides a fast and cost-effective approach for the identification of environmental chemicals that could have detrimental effects on reproduction.

Adverse effects of maternal exposure to bisphenol F on the anxiety- and depression-like behavior of offspring

Bisphenol A (BPA), a well-known endocrine disruptor, is metabolized and eliminated rapidly from the body in adult animals. However, many authors have reported that perinatal BPA exposure alters development of the brain, reproductive system and behavior in the next generation. Recently, BPA substitutes, especially bisphenol F (BPF), have been used because of concerns about the influence of BPA on children, although the actual effects on the next generation are unknown. In this study, we observed behavioral adverse effects of the offspring of mice exposed to BPA or BPF in fetal period. Female C57BL/6 mice were given oral BPA or BPF (0 or 10 mg/kg body weight) daily from gestational day 11.5 to 18.5. The open field test, the elevated plus maze test and the forced swim test were performed at postnatal week 10. BPF exposure altered offspring behavior significantly, resulting in increases in anxiety and depressive state. The influence of BPF was stronger than that of BPA. We demonstrated novel evidence that BPF influences the behavior of offspring.

Gestational and lactational exposure to bisphenol AF in maternal rats increases testosterone levels in 23-day-old male offspring

During prenatal and postnatal development, exposure to environmental chemicals with estrogenic activity, such as bisphenol AF (BPAF), may result in reproductive disorders. Currently, the mechanisms behind such disorders in male offspring induced by gestational and lactational exposure to BPAF remain poorly understood. Here, female rats from gestational day (GD) 3-19 were exposed to 100 mg BPAF/kg/day by oral gavage. On the day of birth (postnatal day (PD) 0), cross-fostering took place between treated and control litters, and cross-fostered mother rats were given BPAF 100 mg/kg/day during the postnatal period (PD 3 to PD 19). HPLC-MS/MS analysis showed that BPAF was transferred via cord blood and lactation, finally bio-accumulating in the offspring testes. Pups exposed to BPAF both prenatally and postnatally showed a significant increase in testis testosterone levels compared with that of the control, while all pups exposed to BPAF showed a significant decrease in testis inhibin B (INHB) levels. Compared with the control, RNA-seq revealed that 279 genes were significantly differentially expressed in the testes of pups exposed to BPAF both prenatally and postnatally, including genes involved in cell differentiation and meiosis. These results indicate that gestational and lactational exposure to BPAF in the mother can impair reproductive function in male offspring.

Bisphenol A and its analogs: Do their metabolites have endocrine activity?

Structural analogs of bisphenol A are commonly used as its alternatives in industrial and commercial applications. Nevertheless, the question arises whether the use of other bisphenols is justified as replacements for bisphenol A in mass production of plastic materials. To evaluate the influence of metabolic reactions on endocrine activities of bisphenols, we conducted a systematic review of the literature. Knowledge about the metabolic pathways and enzymes involved in metabolic biotransformations is essential for understanding and predicting mechanisms of toxicity. Bisphenols are metabolized predominantly by the glucuronidation reaction, which is considered their most important detoxification pathway, as based on current knowledge, glucuronides do not have activity on endocrine receptors. In contrast, several oxidative metabolites of bisphenols with enhanced endocrine activities are presented, and these findings indicate that oxidative metabolites of bisphenols can still have endocrine activities in humans.

Inadvertent exposure to xenoestrogens in children

This article reviews previous studies and presents new data on pesticide exposure in order to provide some indications of the extent and significance of childhood exposure to xenoestrogens, including pesticides, epoxy resins, and polycarbonates. After more than four decades of pesticide use, little is known about their adverse effects on health. There is a need to address the potential risks associated with the current contamination of water, soils, and foods in many agricultural areas. In southeastern Spain, along the Mediterranean coast, extensive areas alongside residential zones are devoted to intensive farming in plastic greenhouses, with the use of large amounts of pesticides. Human tissue samples have been investigated for pesticide residues. Samples of fat from children living in farm areas contained a total of 14 pesticides, including lindane, HCH, heptachlor, aldrin, dieldrin, endrin, endosulfan, o,p′-DDE, and o,p′-DDD, among others. Of the 113 samples studied, 43 were positive for one or more pesticides, some of which have estrogenic activity. The number of new substances that mimic the action of endogenous estrogens is increasing rapidly. These endocrine-disrupting chemicals are not restricted to pesticides. Several different compounds used in the food industry, in plasticizers, and in dental restorations are also estrogenic. The few studies that have investigated their effects in humans all indicate that concerns are warranted. If there is indeed an association between zexposure to substances with hormone-disruptive activity and certain disorders of sexual maturation, the incidence of such disorders should be greater in areas where exposure to agents with this activity is high. We used a spatial ecological design to search for variations in orchidopexy rates and to analyze relationships between these differences and geographical variations in exposure to pesticides. Our results are compatible with a hypothetical association between exposure to hormone-disruptive chemicals and the induction of cryptorchidism. Several methodological limitations in the study design make it necessary to evaluate the results with caution. In conclusion, a closer scrutiny is required to determine whether epoxy resins and polycarbonates contribute, together with estrogenic pesticides, to the exposure of human consumers, especially children, to xenoestrogens.

Pesticide use in the U.S. and policy implications: A focus on herbicides

This article examines herbicide use in the United States, providing estimates of poundage, land surface covered, distribution, and recent trends based on federal and state figures. Herbicides are by far the most widely used class of pesticide in the US, where 556 million lbs of herbicide active ingredients (AIs) were applied in 1995. Agriculture accounts for the majority of herbicide use, totaling 461 million lbs of AIs in 1995. Over 60% of the poundage of all agricultural herbicides consist of those that are capable of disrupting the endocrine and/or reproductive systems of animals. In addition, at least 17 types of `inert ingredients,' which can equal 90% or more of a pesticide product, have been identified as having potential endocrine-disrupting effects. Atrazine is the predominant herbicide used according to poundage, with 68-73 million lbs of AIs applied in 1995. However, 2,4-D is the most widespread herbicide, covering 78 million acres for agricultural uses alone. Both of these herbicides are reported endocrine disruptors. Acetolactate synthase (ALS) inhibitors, namely the sulfonylureas and imidazolinones, are one of the fastest growing classes of herbicides. Many of these herbicides are 100 times more toxic to select plant species than their predecessors, so they can be applied at rates approximately 100 times lower. Consequently, they can affect plant species at concentration levels so low that no standard chemical protocol can detect them. Due in part to these more potent herbicides, the poundage of herbicides used in the US has decreased since the mid-1980s; however, the available data suggest that the number of treated acres has not significantly declined. A thorough assessment of potential exposure to herbicides by wildlife and humans is limited due to the inaccessibility of production and usage data.

A Demonstration of the Uncertainty in Predicting the Estrogenic Activity of Individual Chemicals and Mixtures From an In Vitro Estrogen Receptor Transcriptional Activation Assay (T47D-KBluc) to the In Vivo Uterotrophic Assay Using Oral Exposure

In vitro estrogen receptor assays are valuable tools for identifying environmental samples and chemicals that display estrogenic activity. However, in vitro potency cannot necessarily be extrapolated to estimates of in vivo potency because in vitro assays are currently unable to fully account for absorption, distribution, metabolism, and excretion. To explore this issue, we calculated relative potency factors (RPF), using 17α-ethinyl estradiol (EE2) as the reference compound, for several chemicals and mixtures in the T47D-KBluc estrogen receptor transactivation assay. In vitro RPFs were used to predict rat oral uterotrophic assay responses for these chemicals and mixtures. EE2, 17β-estradiol (E2), benzyl-butyl phthalate (BBP), bisphenol-A (BPA), bisphenol-AF (BPAF), bisphenol-C (BPC), bisphenol-S (BPS), and methoxychlor (MET) were tested individually, while BPS + MET, BPAF + MET, and BPAF + BPC + BPS + EE2 + MET were tested as equipotent mixtures. In vivo ED50 values for BPA, BPAF, and BPC were accurately predicted using in vitro data; however, E2 was less potent than predicted, BBP was a false positive, and BPS and MET were 76.6 and 368.3-fold more active in vivo than predicted from the in vitro potency, respectively. Further, mixture ED50 values were more accurately predicted by the dose addition model using individual chemical in vivo uterotrophic data (0.7-1.5-fold difference from observed) than in vitro data (1.4-86.8-fold). Overall, these data illustrate the potential for both underestimating and overestimating in vivo potency from predictions made with in vitro data for compounds that undergo substantial disposition following oral administration. Accounting for aspects of toxicokinetics, notably metabolism, in in vitro models will be necessary for accurate in vitro-to-in vivo extrapolations.

Bisphenol S and F: A Systematic Review and Comparison of the Hormonal Activity of Bisphenol A Substitutes

BACKGROUND

Increasing concern over bisphenol A (BPA) as an endocrine-disrupting chemical and its possible effects on human health have prompted the removal of BPA from consumer products, often labeled "BPA-free." Some of the chemical replacements, however, are also bisphenols and may have similar physiological effects in organisms. Bisphenol S (BPS) and bisphenol F (BPF) are two such BPA substitutes.

OBJECTIVES

This review was carried out to evaluate the physiological effects and endocrine activities of the BPA substitutes BPS and BPF. Further, we compared the hormonal potency of BPS and BPF to that of BPA.

METHODS

We conducted a systematic review based on the Office of Health Assessment and Translation (OHAT) protocol.

RESULTS

We identified the body of literature to date, consisting of 32 studies (25 in vitro only, and 7 in vivo). The majority of these studies examined the hormonal activities of BPS and BPF and found their potency to be in the same order of magnitude and of similar action as BPA (estrogenic, antiestrogenic, androgenic, and antiandrogenic) in vitro and in vivo. BPS also has potencies similar to that of estradiol in membrane-mediated pathways, which are important for cellular actions such as proliferation, differentiation, and death. BPS and BPF also showed other effects in vitro and in vivo, such as altered organ weights, reproductive end points, and enzyme expression.

CONCLUSIONS

Based on the current literature, BPS and BPF are as hormonally active as BPA, and they have endocrine-disrupting effects.

CITATION

Rochester JR, Bolden AL. 2015. Bisphenol S and F: a systematic review and comparison of the hormonal activity of bisphenol A substitutes.

Bisphenol diglycidyl ethers and bisphenol A and their hydrolysis in drinking water

Epoxy coatings are commonly used to protect the interior (and exterior) surfaces of water mains and storage tanks and can be used on the interior surfaces of water pipes in homes, hospitals, hotels, and other buildings. Common major components of epoxies include bisphenols, such as bisphenol A (BPA) or bisphenol F (BPF), and their reactive prepolymers, bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE), respectively. There currently are health concerns about the safety of BPA and BPF due to known estrogenic effects. Determination of key bisphenol leachates, development of a hydrolysis model, and identification of stable hydrolysis products will aid in assessment of human bisphenol exposure through ingestion of drinking water. Liquid chromatography/mass spectrometry (LC/MS/MS) was used for quantitation of key analytes, and a pseudo-first order kinetic approach was used for modeling. In fill-and-dump studies on epoxy-coated pipe specimens, BADGE and a BPA-like compound were identified as leachates. The BADGE hydrolysis model predicts BADGE half-lives at pH 7 and 15, 25, 35, and 40 °C to be 11, 4.6, 2.0, and 1.4 days respectively; the BFDGE half-life was 5 days at pH 7 and 25 °C. The two identified BADGE hydrolysis products are BADGE-H2O and BADGE 2H2O, with BADGE 2H2O being the final end product under the conditions studied.