Bisphenol A Metabolites and Bisphenol S in Paired Maternal and Cord Serum

Bisphenol S exposure induces intestinal inflammation via altering gut microbiome

Bisphenol S (BPS), a substitute for bisphenol A, is widely used in the manufacture of food packaging materials, raising concern over its toxicity. However, evidence is still lacking on whether gut microbiota involved in BPS induced intestinal inflammation in mammals, as well as its underlying mechanism. Using mouse BPS exposure model, we found intestinal inflammation characterized by shortened colon length, crypt distortion, macrophage accumulation and increased apoptosis. As for gut microbiota, 16s rRNA gene amplicon sequencing showed BPS exposure induced gut dysbiosis, including increased pro-inflammatory microbes such as Ileibacterium, and decreased anti-inflammatory genera such as Lactobacillus, Blautia and Romboutsia. Besides, LC-MS/MS-based untargeted metabolomic analysis indicated BPS impaired both bacteria and host metabolism. Additionally, transcriptome analysis of the intestine revealed abnormal gene expression in intestinal mucosal barrier and inflammation. More importantly, treating mice with antibiotics significantly attenuated BPS-induced gut inflammation via the regulation of both bacterial and host metabolites, indicating the role of gut microbiota. Collectively, BPS exposure induces intestinal inflammation via altering gut microbiota in mouse. This study provides the possibility of madecassic acid, an anti-inflammatory metabolite, to prevent BPS-induced intestinal inflammation and also new insights in understanding host-microbiota interaction in BPS toxicity.

Occurrence of bisphenol analogues and their conjugated metabolites in foodstuff

Bisphenol analogues (BPs) are prevalent in diverse foodstuff samples worldwide. However, the occurrence of conjugated bisphenol A (BPA) and bisphenol S (BPS) metabolites in foodstuff remains poorly understood. This study analyzed eight BPs, and four conjugated BPA and BPS metabolites, in three animal-derived foodstuff and five plant-derived foodstuff samples from China. Results showed that fish foodstuff (9.7 ng/g ww) contained the highest mean concentration of BPA, followed by rice (5.1 ng/g ww) and beans foodstuff (3.6 ng/g ww). BPA-sulfate had higher mean concentrations than BPA-glucuronide in different foodstuff categories, except that in eggs foodstuff (p < 0.05). Compared with other foodstuff items, fish (3.4 ng/g ww) and vegetable (1.6 ng/g ww) foodstuff samples exhibited comparatively higher mean concentrations of BPS. Mean concentrations of BPS-sulfate were consistently higher than BPS-glucuronide in vegetables, meats, and fish foodstuff (p < 0.05). BPA contributed the major total dietary intake (DI) of BPs, with the mean DI of 435 ng/kg bw/day for women and 374 ng/kg bw/day for men, respectively. To our knowledge, this study is the first to investigate the occurrence of conjugated BPA and BPS metabolites in foodstuff, which enhances our comprehension of the origins of these conjugated metabolites in the human body.

Bisphenol S (BPS) induces glioblastoma progression via regulation of EZH2-mediated PI3K/AKT/mTOR pathway in U87-MG cells

Bisphenol S (BPS), an alternative to bisphenol A (BPA), exerts proliferative effects similar to those of BPA. BPS is a representative endocrine disruptor associated with cancer progression. However, the mechanisms underlying BPS-induced glioblastoma progression are not fully understood. To investigate the effects of BPS on glioblastoma, U-87 MG cancer cell lines were exposed to BPS. The study focused on analyzing the proliferation and migration of U-87 MG cells. Furthermore, the involvement of the enhancer of the zeste homolog 2 (EZH2)-mediated phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of the rapamycin (mTOR) pathway was examined. Pharmacological approaches were employed to inhibit EZH2 activity and observe its effects on BPS-induced changes. The results indicated that BPS promoted the proliferation and migration of U-87 MG cells at a concentration of 0.1µM. These changes appeared to be linked to the activation of the EZH2-mediated PI3K/AKT/mTOR pathway. Moreover, inhibiting EZH2 activity using pharmacological approaches restored the BPS-mediated induction of proliferation and migration. In conclusion, the results of this study indicated that BPS induces glioblastoma progression through EZH2 upregulation. Therefore, targeting the EZH2-mediated PI3K/AKT/mTOR pathway could be considered a potential therapeutic strategy for the treatment of glioblastoma.

Distribution, transformation, and toxic effects of the flame retardant tetrabromobisphenol S and its derivatives in the environment: A review

As widely used alternative brominated flame retardants, tetrabromobisphenol S (TBBPS) and its derivatives have attracted increasing amounts of attention in the field of environmental science. Previous studies have shown that TBBPS and its derivatives easily accumulate in environmental media and may cause risks to environmental safety and human health. Therefore, to explore the environmental behaviours of TBBPS and its derivatives, in this paper, we summarized relevant research on the distribution of these compounds in water, the atmosphere, soil and food/biota, as well as their transformation mechanisms (biological and nonbiological) and toxic effects. The summary results show that TBBPS and its derivatives have been detected in water, the atmosphere, soil, and food/biota globally, making them a ubiquitous pollutant. These compounds may be subject to adsorption, photolysis or biological degradation after being released into the environment, which in turn increases their ecological risk. TBBPS and its derivatives can cause a series of toxic effects, such as neurotoxicity, hepatotoxicity, cytotoxicity, thyrotoxicity, genotoxicity and phytotoxicity, to cells or living organisms in in vitro and in vivo exposure. Toxicological studies suggest that TBBPS as an alternative to TBBPA is not entirely environmentally friendly. Finally, we propose future directions for research on TBBPS and its derivatives, including the application of new technologies in studies on the migration, transformation, toxicology and human exposure risk assessment of TBBPS and its derivatives in the environment. This review provides useful information for obtaining a better understanding of the behaviour and potential toxic effects of TBBPS and its derivatives in the environment.

Bisphenol S causes excessive estrogen synthesis by activating FSHR and the downstream cAMP/PKA signaling pathway

Estrogen excess in females has been linked to a diverse array of chronic and acute diseases. Emerging research shows that exposure to estrogen-like compounds such as bisphenol S leads to increases in 17β-estradiol levels, but the mechanism of action is unclear. The aim of this study was to reveal the underlying signaling pathway-mediated mechanisms, target site and target molecule of action of bisphenol S causing excessive estrogen synthesis. Human ovarian granulosa cells SVOG were exposed to bisphenol S at environmentally relevant concentrations (1 μg/L, 10 μg/L, and 100 μg/L) for 48 h. The results confirms that bisphenol S accumulates mainly on the cell membrane, binds to follicle stimulating hormone receptor (FSHR) located on the cell membrane, and subsequently activates the downstream cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) signaling pathway, leading to enhanced conversion of testosterone to 17β-estradiol. This study deepens our knowledge of the mechanisms of environmental factors in pathogenesis of hyperestrogenism.

Associations of prenatal exposure to bisphenols with BMI growth trajectories in offspring within the first two years: evidence from a birth cohort study in China

BACKGROUND

Prenatal bisphenol exposure has been reported to be associated with lower birth weight and obesity-related indicators in early childhood. These findings warrant an investigation of the relationship between prenatal bisphenol exposure and the dynamic growth of offspring. This study aimed to evaluate the relationship of maternal bisphenol concentration in urine with the body mass index (BMI) growth trajectory of children aged up to two years and to identify the critical exposure periods.

METHODS

A total of 826 mother-offspring pairs were recruited from Wuhan Children's Hospital between November 2013 and March 2015. Maternal urine samples collected during the first, second, and third trimesters were analyzed for bisphenol A (BPA), bisphenol S, and bisphenol F (BPF) concentrations. Measurements of length and weight were taken at 0, 1, 3, 6, 8, 12, 18, and 24 months. Children's BMI was standardized using the World Health Organization reference, and group-based trajectory modeling was used to identify BMI growth trajectories. The associations between prenatal bisphenol exposure and BMI growth trajectory patterns were assessed using multinomial logistic regression models.

RESULTS

The BMI growth trajectories of the 826 children were categorized into four patterns: low-stable (n = 134, 16.2%), low-increasing (n = 142, 17.2%), moderate-stable (n = 350, 42.4%), and moderate-increasing (n = 200, 24.2%). After adjusting for potential confounders, we observed that prenatal exposure to BPA during the second trimester [odds ratio (OR) = 2.20, 95% confidence interval (CI) = 1.09-4.43] and BPF during the third trimester (OR = 3.28, 95% CI = 1.55-6.95) at the highest quartile concentration were associated with an increased likelihood of the low-increasing BMI trajectory. Furthermore, in the subgroup analysis by infant sex, the positive association between the highest quartile of prenatal average urinary BPF concentration during the whole pregnancy and the low-increasing BMI trajectory was found only in girls (OR = 2.82, 95% CI = 1.04-7.68).

CONCLUSION

Our study findings suggest that prenatal exposure to BPA and BPF (a commonly used substitute for BPA) is associated with BMI growth trajectories in offspring during the first two years, increasing the likelihood of the low-increasing pattern. Video Abstract (MP4 120033 kb).

Conjugated metabolites of bisphenol A and bisphenol S in indoor dust, outdoor dust, and human urine

Bisphenol A (BPA) and bisphenol S (BPS) have been widely spread in the global environment. However, for conjugated BPA and BPS metabolites, limited studies have investigated their occurrence in environmental matrices. We collected paired indoor and outdoor dust (n = 97), as well as human urine (n = 153) samples, from residential houses in Quzhou, China, and measured these samples for 8 conjugated BPA and BPS metabolites. Three BPA metabolites were found in collected indoor and outdoor dust, with BPA sulfate (mean 0.75 and 1.3 ng/g, respectively) and BPA glucuronide (0.13 and 0.26 ng/g) being more abundant. BPA conjugates accounted for a mean of 42 and 56% of total BPA (sum of conjugated BPA and BPA metabolites) in indoor and outdoor dust, respectively. BPS sulfate (mean 0.29 and 0.82 ng/g, respectively) had consistently higher concentrations than BPS glucuronide (0.13 and 0.27 ng/g) in indoor and outdoor samples. BPS conjugates contributed a mean 32% and 45% of total BPS (sum of BPS and BPS metabolites) in indoor and outdoor dust, respectively. Moreover, conjugated BPA and BPS metabolites in indoor or outdoor dust were not significantly correlated with those in urine from residents. Overall, this study first demonstrates the wide presence of conjugated BPA and BPS metabolites, besides BPA and BPS, in indoor and outdoor dust. These data are important for elucidating the sources of conjugated BPA and BPS metabolites in the human body.

Conjugated bisphenol S metabolites in human serum and whole blood

Studies have shown that bisphenol S (BPS) is mainly present as its conjugated metabolites in human blood. However, the distribution of conjugated BPS metabolites in different human blood matrices has not been characterized. In this study, paired human serum and whole blood samples (n = 79) were collected from Chinese participants, and were measured for the occurrence of BPS and 4 BPS metabolites. BPS was detectable in 49% of human serum ( Collapse

Key Words

• BPS-G
• BPS-S
• Distribution
• Serum
• Whole blood

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MESH Headings

• Humans
• Phenols/blood
• Phenols/metabolism
• Sulfones/blood
• Sulfones/metabolism
• Male
• Female
• Environmental Pollutants/blood
• Environmental Pollutants/metabolism
• Adult
• Glucuronides/blood
• Glucuronides/metabolism
• Sulfuric Acid Esters/blood
• Middle Aged

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Grants Collapse

Affiliation(s)

Zhenling Fu Department of Pharmacy, Quzhou Affiliated Hospital of Wenzhou Medical University, Quzhou People's Hospital, Quzhou, Zhejiang, 324000, PR China
Hangbiao Jin Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang, 310014, PR China
Weili Mao Department of Pharmacy, Quzhou Affiliated Hospital of Wenzhou Medical University, Quzhou People's Hospital, Quzhou, Zhejiang, 324000, PR China
Zefu Hu Department of Pharmacy, Quzhou Affiliated Hospital of Wenzhou Medical University, Quzhou People's Hospital, Quzhou, Zhejiang, 324000, PR China.

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Prenatal exposure to environmental contaminants and cord serum metabolite profiles in future immune-mediated diseases

BACKGROUND

Prenatal exposure to environmental contaminants is a significant health concern because it has the potential to interfere with host metabolism, leading to adverse health effects in early childhood and later in life. Growing evidence suggests that genetic and environmental factors, as well as their interactions, play a significant role in the development of autoimmune diseases.

OBJECTIVE

In this study, we hypothesized that prenatal exposure to environmental contaminants impacts cord serum metabolome and contributes to the development of autoimmune diseases.

METHODS

We selected cord serum samples from All Babies in Southeast Sweden (ABIS) general population cohort, from infants who later developed one or more autoimmune-mediated and inflammatory diseases: celiac disease (CD), Crohn's disease (IBD), hypothyroidism (HT), juvenile idiopathic arthritis (JIA), and type 1 diabetes (T1D) (all cases, N = 62), along with matched controls (N = 268). Using integrated exposomics and metabolomics mass spectrometry (MS) based platforms, we determined the levels of environmental contaminants and metabolites.

RESULTS

Differences in exposure levels were found between the controls and those who later developed various diseases. High contaminant exposure levels were associated with changes in metabolome, including amino acids and free fatty acids. Specifically, we identified marked associations between metabolite profiles and exposure levels of deoxynivalenol (DON), bisphenol S (BPS), and specific per- and polyfluorinated substances (PFAS).

IMPACT STATEMENT

Abnormal metabolism is a common feature preceding several autoimmune and inflammatory diseases. However, few studies compared common and specific metabolic patterns preceding these diseases. Here we hypothesized that exposure to environmental contaminants impacts cord serum metabolome, which may contribute to the development of autoimmune diseases. We found differences in exposure levels between the controls and those who later developed various diseases, and importantly, on the metabolic changes associated with the exposures. High contaminant exposure levels were associated with specific changes in metabolome. Our study suggests that prenatal exposure to specific environmental contaminants alters the cord serum metabolomes, which, in turn, might increase the risk of various immune-mediated diseases.

Spatiotemporal distribution, source apportionment, and ecological risk of bisphenol analogues in a highly urbanized river basin

Bisphenol analogues (BPs), as one of the endocrine disruptors, have received wide attention due to their adverse impacts on ecosystems. However, the seasonal spatiotemporal distribution, source apportionment, and ecological risk of BPs in natural basins are poorly understood. Especially in highly urbanized river basins with the extensive economic development and anthropogenic activities threaten these critical but ecologically fragile regions. In this study, field investigations of BPs in the waters of the entire Qinhuai River Basin (QRB) were conducted in June (before the annual flood period) and August (after the annual flood period) 2023. The Qinhuai River, an important primary tributary of the lower Yangtze River, is located in eastern China and the QRB is characterized by a high population density and dense urbanization. Thirty-two sites were sampled for six types of BPs known to be ubiquitous in the surface water of the QRB. Significant differences in the concentrations of those BPs were found. Specifically, the concentration of total BPs (ΣBPs) was significantly higher before than after the flood period: 20.3-472 ng/L (mean = 146 ng/L) and 14.1-105 ng/L (mean = 35.9 ng/L), respectively. BPA was the main contributor to ΣBPs before the flood, and BPB followed by BPA after the flood. ΣBP concentrations were 12-241 % higher downstream than upstream of wastewater treatment plants (WWTPs). The results of a principal component analysis followed by multiple linear regression (PCA-MLR) suggested that untreated wastewater discharge from the WWTPs is an important source of BPs in the basin, with urban rainfall runoff as another potential source after the flood period. An assessment of the ecological risk of BPs, based on a calculation of the risk quotient, showed that BPA and BPS should be given due attention, and overall ecological risk of BPs pose a low risk to local algae but high and medium risks to invertebrates and fish, respectively.

Mode of action exploration of reproductive toxicity induced by bisphenol S using human normal ovarian epithelial cells through ERβ-MAPK signaling pathway

BACKGROUND

In the plastics production sector, bisphenol S (BPS) has gained popularity as a replacement for bisphenol A (BPA). However, the mode of action (MOA) of female reproductive toxicity caused by BPS remains unclear and the safety of BPS is controversial.

METHODS

Human normal ovarian epithelial cell line, IOSE80, were exposed to BPS at human-relevant levels for short-term exposure at 24 h or 48 h, or for long-term exposure at 28 days, either alone or together with five signaling pathway inhibitors: ICI 18,2780 (estrogen receptor [ER] antagonist), G15 (GPR30 specific inhibitor), U0126 (extracellular regulated protein kinase [ERK] 1/2 inhibitor), SP600125 (c-Jun N-terminal kinase [JNK] inhibitor) or SB203580 (p38 mitogen‑activated protein kinase [p38MAPK] inhibitor). MOA through ERβ-MAPK signaling pathway interruption was explored, and potential thresholds were estimated by the benchmark dose method.

RESULTS

For short-term exposure, BPS exposure at human-relevant levels elevated the ESR2 and MAPK8 mRNA levels, along with the percentage of the G0/G1 phase. For long-term exposure, BPS raised the MAPK1 and EGFR mRNA levels, the ERβ, p-ERK, and p-JNK protein levels, and the percentage of the G0/G1 phase, which was partly suppressed by U0126. The benchmark dose lower confidence limit (BMDL) of the percentage of the S phase after 24 h exposure was the lowest among all the BMDLs of a good fit, with BMDL5 of 9.55 μM.

CONCLUSIONS

The MOA of female reproductive toxicity caused by BPS at human-relevant levels might involve: molecular initiating event (MIE)-BPS binding to ERβ receptor, key event (KE)1-the interrupted expression of GnRH, KE2-the activation of JNK (for short-term exposure) and ERK pathway (for long-term exposure), KE3-cell cycle arrest (the increased percentage of the G0/G1 phase), and KE4-interruption of cell proliferation (only for short-term exposure). The BMDL of the percentage of the S phase after 24 h exposure was the lowest among all the BMDLs of a good fit, with BMDL5 of 9.55 μM.

Chemical mixture that targets the epidermal growth factor pathway impairs human trophoblast cell functions

Pregnant women are exposed to complex chemical mixtures, many of which reach the placenta. Some of these chemicals interfere with epidermal growth factor receptor (EGFR) activation, a receptor tyrosine kinase that modulates several placenta cell functions. We hypothesized that a mixture of chemicals (Chem-Mix) known to reduce EGFR activation (polychlorinated biphenyl (PCB)-126, PCB-153, atrazine, trans-nonachlor, niclosamide, and bisphenol S) would interfere with EGFR-mediated trophoblast cell functions. To test this, we determined the chemicals' EGFR binding ability, EGFR and downstream effectors activation, and trophoblast functions (proliferation, invasion, and endovascular differentiation) known to be regulated by EGFR in extravillous trophoblasts (EVTs). The Chem-Mix competed with EGF for EGFR binding, however only PCB-153, niclosamide, trans-nonachlor, and BPS competed for binding as single chemicals. The effects of the Chem-Mix on EGFR phosphorylation were tested by exposing the placental EVT cell line, HTR-8/SVneo to control (0.1% DMSO), Chem-Mix (1, 10, or 100 ng/ml), EGF (30 ng/ml), or Chem-Mix + EGF. The Chem-Mix - but not the individual chemicals - reduced EGF-mediated EGFR phosphorylation in a dose dependent manner, while no effect was observed in its downstream effectors (AKT and STAT3). None of the individual chemicals affected EVT cell invasion, but the Chem-Mix reduced EVT cell invasion independent of EGF. In support of previous studies that have explored chemicals targeting a specific pathway (estrogen/androgen receptor), current findings indicate that exposure to a chemical mixture that targets the EGFR pathway can result in a greater impact compared to individual chemicals in the context of placental cell functions.

Acute Exposure to Bisphenol S Decreases In Vitro Right Atrial Contractility in Rats

AIM/OBJECTIVE

Bisphenols are widely used in the manufacturing of polycarbonate material and epoxy resins which constitute the essential component of plastic. Bisphenol A (BPA) has been reported to produce toxicity on organs in both animal and human studies. Therefore, plastic manufacturers are replacing BPA with other analogues that are considered to be safe, and BPA-free products are now available in the market. However, some studies have reported that bisphenol-S (BPS) also possesses toxic properties. It has been reported to depress ventricular contraction as well as produce ventricular arrhythmia on acute exposure. The present study was performed to examine the effect of BPS on in vitro spontaneously-beating right atria in rats.

METHODS

In the present study, in vitro spontaneous contractions of right atria obtained from adult female rats of the Wistar strain were recorded. The atria were exposed to BPS (10-6-10 mM) and its effects on atrial contractions were recorded in the form of cumulative-concentration response with and without administration of antagonists namely atropine, L-NAME, and methylene blue.

RESULTS

BPS decreased the rate as well as the force of atrial contractions. The changes produced in the rate and force of atrial contractions were not attributed to ethanol, which was used to prepare BPS solutions. The decrease in right atrial contractility produced by BPS was blocked by L-NAME; however, atropine and methylene blue were not able to antagonize the effects of BPS on atria.

CONCLUSIONS

The present study indicates the involvement of NO-dependent but cGMP independent pathway responsible for BPS-induced cardio-toxicity.

A Critical Review on the Opportunity to Use Placenta and Innovative Biomonitoring Methods to Characterize the Prenatal Chemical Exposome

Adverse effects associated with chemical exposures during pregnancy include several developmental and reproductive disorders. However, considering the tens of thousands of chemicals present on the market, the effects of chemical mixtures on the developing fetus is still likely underestimated. In this critical review, we discuss the potential to apply innovative biomonitoring methods using high-resolution mass spectrometry (HRMS) on placenta to improve the monitoring of chemical exposure during pregnancy. The physiology of the placenta and its relevance as a matrix for monitoring chemical exposures and their effects on fetal health is first outlined. We then identify several key parameters that require further investigations before placenta can be used for large-scale monitoring in a robust manner. Most critical is the need for standardization of placental sampling. Placenta is a highly heterogeneous organ, and knowledge of the intraplacenta variability of chemical composition is required to ensure unbiased and robust interindividual comparisons. Other important variables include the time of collection, the sex of the fetus, and mode of delivery. Finally, we discuss the first applications of HRMS methods on the placenta to decipher the chemical exposome and describe how the use of placenta can complement biofluids collected on the mother or the fetus.

Occurrence, placental transfer, and health risks of emerging endocrine-disrupting chemicals in pregnant women

Previous studies demonstrated that many environmental chemicals can cross the human placental barrier. However, the risk regarding gestational exposure of emerging endocrine-disrupting chemicals (EDCs) is unclear. In this study, the occurrence of 24 EDCs, such as bisphenol A analogs, parabens, triclocarban, and triclosan, was investigated in serum and urine samples from Chinese pregnant women. Some metabolites were determined in matched serum-urine pairs (n = 75) to perform a comprehensive assessment of exposure. The placental transfer efficiency (PTE) of the detected chemicals was determined in matched maternal-cord serum pairs (n = 110). The mean PTEs of the chemicals showed a large variation from 43.1% to 171.0%. The potential effects of physicochemical properties, molecular structures, and biological factors on PTE were investigated using multiple linear regression models and molecular docking. We found that the PTE of methyl paraben, ethyl paraben, and propyl paraben was associated with their increasing alkyl chain lengths. Furthermore, a comprehensive exposure assessment of EDCs showed that 62.7% of pregnant women had a health index > 1, which indicted potential health risks during pregnancy. However, toxicity and the underlying mechanisms of these EDCs remain to be further studied.

Profile, Tissue Distribution, and Time Trend of Bisphenol Plastic Additives in Freshwater Wildlife of the Pearl River Ecosystem, China

Plastic-related contaminants in the environment have attracted increasing attention, with plastic pollution becoming a serious issue globally. The present study investigated the potential bioaccumulation and biotransfer of bisphenol (BP) compounds that are widely added in various products such as plastics and other products in a freshwater ecosystem, China. Among commonly applied 14 BP analogues, bisphenol A (BPA), bisphenol F (BPF), and bisphenol S (BPS) were predominant, representing 64%-100% of the total concentrations of BPs (ΣBPs) in freshwater wildlife. Both the concentrations and analogue profiles in the fish showed seasonal differences and species dependence. Higher BP concentrations were observed in fish collected during the dry season than the wet season. Higher percentages of non-BPA analogues (e.g., BPS and BPF) were observed in fish collected during the wet season. Pelagic species accumulated notably higher levels of BPs than midwater and bottom species. The liver generally contained the highest ΣBPs, followed successively by the swim bladder, belly fat, and dorsal muscle. The analogue profile also showed some differences among tissues, varying by species and season. Lower ΣBPs but higher percentages of non-BPA analogues were observed in female than male common carp. Time trends of the BPA concentration in fish varied by species, probably related to habitats and diets of the fish. Habitats, feeding behaviors, and trophic transfer may have significant impacts on exposure of wildlife to BPs in natural ecosystems. The BPs did not demonstrate strong potential for bioaccumulation. More research is warranted about metabolism and transgenerational transfer of BPs in wildlife to fully reveal the bioaccumulation and consequently ecological risks of these chemicals in the environment. Environ Toxicol Chem 2023;42:2130-2142. © 2023 SETAC.

Bisphenol A Imprinted Electrochemical Sensor Based on Graphene Quantum Dots with Boron Functionalized g-C3N4 in Food Samples

A molecular imprinted electrochemical sensor based on boron-functionalized graphitic carbon nitride (B-g-C₃N₄) and graphene quantum dots (GQDs) was presented for selective determination of bisphenol A (BPA). In particular, by combining the selectivity and high stability properties, which are the most important advantages of molecular imprinted polymers, and the highly sensitive properties of GQDs/B-g-C₃N₄ nanocomposite, a highly selective and sensitive analytical method was developed for BPA analysis. Firstly, GQDs/B-g-C₃N₄ nanocomposite was characterized by using microscopic, spectroscopic, and electrochemical techniques. This novel molecular imprinted electrochemical sensor for BPA detection demonstrated a linearity of 1.0 × 10^-11-1.0 × 10^-9 M and a low detection limit (LOD, 3.0 × 10^-12 M). BPA-imprinted polymer on GQDs/B-g-C₃N₄ nanocomposite also showed good stability, repeatability and selectivity in food samples.

Prenatal bisphenol S exposure induces hepatic lipid deposition in male mice offspring through downregulation of adipose-derived exosomal miR-29a-3p

The increased usage of bisphenol S (BPS) results in wide distribution in pregnant women. In this study, pregnant mice were given multiple-dose BPS during gestation. Results showed that prenatal BPS exposure (50 μg/kg/day) induced increased weight gain, dyslipidemia, higher liver triglyceride (TG), adipocyte hypertrophy, and hepatic lipid deposition in male offspring. Exosomes play important roles in regulating lipid metabolism. Here, serum exosomes and adipose miRNA sequencing of male offspring indicated a remarkable decrease in miR-29a-3p expression. To clarify whether adipocyte-derived exosomes mediate hepatic lipid deposition, exosomes were extracted from BPS-treated adipocytes and co-cultured with hepatocytes. These exosomes could be taken up by hepatocytes and promoted lipid deposition, and notably, exosomal miR-29a-3p was downregulated. Furthermore, miR-29a-3p knockdown in adipocyte-derived exosomes promoted hepatocyte lipid deposition, whereas overexpression led to the opposite effect. Also, the role of miR-29a-3p was demonstrated in hepatocytes by overexpressing or knocking it down. Subsequent studies have shown that miR-29a-3p can promote lipid deposition by directly targeting Col4a1. Taken together, prenatal BPS exposure could lead to lower miR-29a-3p yield in adipocyte-derived exosomes and decrease miR-29a-3p content transported to hepatocytes, which further negatively regulate Col4a1 and promote hepatic lipid deposition. Our findings provided clues to maternal environmental exposure-induced liver metabolic diseases.

Oxidative damage contributes to bisphenol S-induced development block at 2-cell stage preimplantation embryos in mice through inhibiting of embryonic genome activation

Although bisphenol S (BPS), as a bisphenol A (BPA) substitute, has been widely used in the commodity, it is embryotoxic in recent experiments. Nowadays, it remains unclear how BPS affects preimplantation embryos. Here, my team investigated the effects of BPS on preimplantation embryos and the possible molecular mechanisms in mice. The results showed that 10^-6 mol/L BPS exposure delayed the blastocysts stage, and exposure to 10^-4 mol/L BPS induced 2-cell block in mice preimplantation embryos. A significant increase in reactive oxygen species (ROS) level and antioxidant enzyme genes Sod1, Gpx1, Gpx6, and Prdx2 expression were shown, but the level of apoptosis was normal in 2-cell blocked embryos. Further experiments demonstrated that embryonic genome activation (EGA) specific genes Hsp70.1 and Hsc70 were significantly decreased, which implied that ROS and EGA activation have the potential to block 2-cell development. Antioxidant enzymes, including superoxide dismutase (SOD), coenzyme Q10 (CoQ10), and folic acid (FA) were used to further explore the roles of ROS and EGA in 2-cell block. Only 1200 U/mL SOD was found to alleviate the phenomenon of 2-cell block, reduce oxidative damage, and restore the expression of EGA-specific genes Hsp70.1 and Hsc70. Conclusively, this study demonstrates for the first time that BPS can induce 2-cell block, which is mainly mediated by ROS aggregation and results in the failure of EGA activation.

Derivatized versus non-derivatized LC-MS/MS techniques for the analysis of estrogens and estrogen-like endocrine disruptors in human plasma

Bisphenols, parabens, alkylphenols and triclosan are anthropogenic substances with a phenolic group that have been introduced to the environment in recent decades. As they possess hormone-like effects, they have been termed endocrine disruptors (EDs), and can interfere with steroid pathways in organisms. To evaluate the potential impact of EDs on steroid biosynthesis and metabolism, sensitive and robust methods enabling the concurrent measurement of EDs and steroids in plasma are needed. Of crucial importance is the analysis of unconjugated EDs, which possess biological activity. The aim of the study was to develop and validate LC-MS/MS methods with and without a derivatization step for the analysis of unconjugated steroids (estrone-E1, estradiol-E2, estriol-E3, aldosterone-ALDO) and different groups of EDs (bisphenols, parabens, nonylphenol-NP and triclosan-TCS), and compare these methods on a set of 24 human plasma samples using Passing-Bablok regression analysis. Both methods were validated according to FDA and EMA guidelines. The method with dansyl chloride derivatization allowed 17 compounds to be measured: estrogens (E1, E2, E3), bisphenols (bisphenol A-BPA, BPS, BPF, BPAF, BPAP, BPZ, BPP), parabens (methylparaben-MP, ethylparaben-EP, propylparaben-PP, butylparaben-BP, benzylparaben-BenzylP), TCS and NP, with lower limits of quantification (LLOQs) between 4 and 125 pg/mL. The method without derivatization enabled 15 compounds to be analyzed: estrogens (E1, E2, E3), ALDO, bisphenols (BPA, BPS, BPF, BPAF, BPAP, BPZ), parabens (MP, EP, PP, BP, BenzylP) with LLOQs between 2 and 63 pg/mL, and NP and BPP in semiquantitative mode. Adding 6 mM ammonium fluoride post column into mobile phases in the method without derivatization achieved similar or even better LLOQs than the method with the derivatization step. The uniqueness of the methods lies in the simultaneous determination of different classes of unconjugated (bioactive) fraction of EDs together with selected steroids (estrogens + ALDO in the method without derivatization), which provides a useful tool for evaluating the relationships between EDs and steroid metabolism.

Prenatal bisphenol exposure and intelligence quotient in children at six years of age: A prospective cohort study

The effects of prenatal bisphenol A (BPA) exposure on children's cognitive development have been reported; however, relevant evidence on BPA analogues was limited, with rare evidence of the joint effect of their mixture. Among 424 mother-offspring pairs from the Shanghai-Minhang Birth Cohort Study, maternal urinary concentrations of five bisphenols (BPs) were quantified, and children's cognitive function was assessed by the Wechsler Intelligence Scale at six years of age. We assessed the associations of prenatal exposure to individual BPs with children's intelligence quotient (IQ) and analyzed the joint effect of BPs mixture by the Quantile g-computation model (QGC) and Bayesian kernel machine regression model (BKMR). QGC models showed that higher maternal urinary BPs mixture concentrations were associated with lower scores among boys in a non-linear way; however, no association was observed in girls. For individual effects, BPA and BPF were associated with decreased IQ scores in boys and were identified as important contributors to the joint effect of BPs mixture. However, associations of BPA with increased IQ scores in girls, and TCBPA with increased IQ scores in both sexes were observed. Our findings suggested prenatal exposure to BPs mixture may affect children's cognitive function in a sex-specific pattern and provided evidence of the neurotoxicity of BPA and BPF.

The bisphenol S contamination level observed in human follicular fluid affects the development of porcine oocytes

Bisphenol S (BPS), the main replacement for bisphenol A (BPA), is thought to be toxic, but limited information is available on the effects of Bisphenol S on ovarian follicles. In our study, we demonstrated the presence of Bisphenol S in the follicular fluid of women at a concentration of 22.4 nM. The effect of such concentrations of Bisphenol S on oocyte maturation and subsequent embryo development is still unknown. Therefore, we focused on the effect of Bisphenol S on in vitro oocyte maturation, fertilization, and embryo development. As a model, we used porcine oocytes, which show many physiological similarities to human oocytes. Oocytes were exposed to Bisphenol S concentrations similar to those detected in female patients in the ART clinic. We found a decreased ability of oocytes to successfully complete meiotic maturation. Mature oocytes showed an increased frequency of meiotic spindle abnormalities and chromosome misalignment. Alarming associations of oocyte Bisphenol S exposure with the occurrence of aneuploidy and changes in the distribution of mitochondria and mitochondrial proteins were demonstrated for the first time. However, the number and quality of blastocysts derived from oocytes that successfully completed meiotic maturation under the influence of Bisphenol S was not affected.

Influence of Gut Microbiota on Metabolism of Bisphenol A, a Major Component of Polycarbonate Plastics

Bisphenol A (BPA) is a major component of polycarbonate plastics and epoxy resins. While many studies have investigated the effect BPA exposure has upon changes in gut microbial communities, the influence of gut microbiota on an organism's ability to metabolize BPA remains comparatively unexplored. To remedy this, in this study, Sprague Dawley rats were intermittently (i.e., at a 7-day interval) or continuously dosed with 500 μg BPA/kg bw/day for 28 days, via oral gavage. In the rats which underwent the 7-day interval BPA exposure, neither their metabolism of BPA nor their gut microbiota structure changed greatly with dosing time. In contrast, following continuous BPA exposure, the relative level of Firmicutes and Proteobacteria in the rats' guts significantly increased, and the alpha diversity of the rats' gut bacteria was greatly reduced. Meanwhile, the mean proportion of BPA sulfate to total BPA in rat blood was gradually decreased from 30 (on day 1) to 7.4% (by day 28). After 28 days of continuous exposure, the mean proportion of BPA glucuronide to total BPA in the rats' urine elevated from 70 to 81%, and in the rats' feces the mean proportion of BPA gradually decreased from 83 to 65%. Under continuous BPA exposure, the abundances of 27, 25, and 24 gut microbial genera were significantly correlated with the proportion of BPA or its metabolites in the rats' blood, urine, and feces, respectively. Overall, this study principally aimed to demonstrate that continuous BPA exposure disrupted the rats' gut microbiota communities, which in turn altered the rats' metabolism of BPA. These findings contribute to the better understanding of the metabolism of BPA in humans.

Effects of prenatal exposure to bisphenols on newborn leucocyte telomere length: a prospective birth cohort study in China

Telomere length (TL) at birth is related to diseases that may arise in the future and long-term health. Bisphenols exhibit toxic effects and can cross the placenta barrier. However, the effects of prenatal exposure to bisphenols on newborn TL remain unknown. We aimed to explore the effects of prenatal exposure to bisphenols (i.e., bisphenol A [BPA], bisphenol B [BPB], bisphenol F [BPF], bisphenol S [BPS] and tetrabromobisphenol A [TBBPA]) on relative TL in newborns. A total of 801 mother-infant pairs were extracted from the Guangxi Zhuang Birth Cohort. The relationship between bisphenol levels in maternal serum and relative TL in cord blood was examined by generalized linear models and restricted cubic spline (RCS) models. After adjusting for confounders, we observed a 3.19% (95% CI: -6.08%, -0.21%; P = 0.037) reduction in relative cord blood TL among mothers ≥ 28 years old, with each onefold increase in BPS. However, in each onefold increase of TBBPA, we observed a 3.31% (95% CI: 0.67%, 6.01%; P = 0.014) increase in relative cord blood TL among mothers < 28 years old. The adjusted RCS models revealed similar results (P overall < 0.05, P non-linear > 0.05). This study was the first to establish a positive association between serum TBBPA levels and relative TL in newborns born to young mothers. However, BPS levels were inversely correlated with TL in fetus born to old mothers. The results suggested that the fetus of old pregnant women may be more sensitive to BPS exposure. Moreover, BPS exposure early in life may accelerate aging or increase the risk of developing BPS-related diseases in later life.

Evaluation of toxicological effects of bisphenol S with an in vitro human bone marrow mesenchymal stem cell: Implications for bone health

As the use of bisphenol A (BPA) has been restricted in consumer products, bisphenol S (BPS) is one major alternative to BPA for various materials, leading to growing concerns about its health risks in human beings. However, little is known about the toxic effects of BPS on bone health. We employed human bone marrow mesenchymal stem cells (hBMSCs) for the in vitro assessment of BPS on cell proliferation, differentiation, and self-renewal. Our study revealed that BPS at concentrations of 10^-10-10^-7 M increased cell viability but induced the morphological changes of hBMSCs. Moreover, BPS decreased ROS generation and increased Nrf2 expression. Furthermore, BPS not only activated ERα/β expression but also increased β-catenin expression and induced the replicative senescence of hBMSCs. Furthermore, we found that the upregulation of β-catenin induced by BPS was mediated, in part, by ER signaling. Overall, our results suggested BPS exposure caused the homeostatic imbalance of hBMSCs.

Twenty bisphenol analogues in take-out polystyrene-made food containers: concentration levels, simulated migration, and risk evaluation

Bisphenol A (BPA) is mainly used to produce polycarbonate consumer products. However, the occurrence of BPA and other bisphenol analogues (BPs) in polystyrene-made plastic products, such as white foam take-out containers (WFTOCs), has not been well investigated. In this study, occurrence of 20 BPs in WFTOC samples collected from China, Canada, and Poland were investigated with a sample size of 152. Results showed that 11 out of 20 BPs have been detected at least in one WFTOC sample. Among them, BPA was the most frequently detected BP, followed by bisphenol S (BPS) and bisphenol AF, while BPF was the least detected BP. Very high concentrations of BPA and BPS were detected in WFTOCs from China (mean 2694 and 552 ng/g), compared with Canada (81 and 45 ng/g, respectively) and Poland (95 and 16 ng/g). Other BPs, such as bisphenol TMC (BPTMC; detection frequency 65%, range < LOQ - 224 ng/g), bisphenol G (17%, < LOQ - 11 ng/g), and bisphenol BP (11%, < LOQ - 1.6 ng/g), were also detected in Chinese WFTOC samples. The mean partitioning coefficients of BPA, BPS, bisphenol AP, and BPTMC between WFTOCs and tap water, 10% ethanol, 50% ethanol, corn oil, or steamed rice were 0.22 - 2.9%, 0.16 - 5.1%, 0.11 - 7.5%, 2.3 - 6.5%, or 0.19 - 0.36%, respectively. The estimated daily intake of BPA, BPS, and BPTMC through using WFTOCs were 0.50 - 547, 0.054 - 229, and < 0.66 ng/kg bw/day, respectively, for general population in China, Canada, and Poland. Overall, this study first reveals the unexpected presence of BPs in WFTOCs made of polystyrene, which contributes to the better understanding of the sources of human exposure to BPs.

Association between urinary bisphenol analogue concentrations and lung cancer in adults: A case-control study

Elevated urinary bisphenol A (BPA) concentrations have been associated with lung cancer in humans. However, toxicological studies demonstrated that the proliferation of lung cancer cells was inhibited by BPA exposure. Therefore, it is still necessary to determine whether exposure to BPA and other bisphenol analogues (BPs) is associated with lung cancer in humans. In this study, 226 lung cancer patients and 243 controls were randomly recruited. Concentrations of three BPs in human urine were quantified and their relationships with the risk of human lung cancer were evaluated. BPA (mean 1.03 ng/mL, 0.87 μg/g Cre) was the predominant BP in human urine, followed by bisphenol S (BPS) (0.72 ng/mL, 0.53 μg/g Cre) and bisphenol F (0.32 ng/mL, 0.37 μg/g Cre). Significant correlations between creatinine-corrected urinary BPA concentrations and the lung cancer risk (odds ratio (OR) _adjusted = 1.28, 95% confidence interval (CI): 1.17, 1.40; P_trend = 0.04) were found using logistical regression analysis. Creatinine-corrected urinary concentrations of BPS in participants showed significant correlations with lung cancer (OR_adjusted = 1.23, 95% CI: 1.04, 1.59; P_trend = 0.01) in the adjusted model. In the stratification analysis, the significant correlation between urinary creatinine-corrected concentrations of BPA and the risk of lung cancer still observed in male participants (OR = 1.36, 95% CI: 1.09, 1.62, p = 0.040). This study demonstrates that elevated human exposure to BPA and BPS may be associated with the increased lung cancer risk.

Placental transfer of bisphenol diglycidyl ethers (BDGEs) and its association with maternal health in a population in South of China

Despite high production and usage, little is known about exposure to bisphenol diglycidyl ethers (BDGEs) and their derivatives in pregnant women and fetuses. In this study, we determined nine BDGEs in 106 paired maternal and cord serum samples collected from e-waste dismantling sites in South of China. Bisphenol A bis (2,3-dihydroxypropyl) glycidyl ether (BADGE·2H2O), bisphenol A (3-chloro-2-hydroxypropyl) (2,3-dihydroxypropyl) glycidyl ether (BADGE·HCl·H2O), and bisphenol F diglycidyl ether (BFDGE) were the major BDGEs, with median concentrations of 0.57, 4.07, and 1.60 ng/mL, respectively, in maternal serum, and of 3.58, 5.61, and 0.61 ng/mL, respectively, in cord serum. The transplacental transfer efficiencies (TTEs) were estimated for BDGEs found in samples, and median values were in the range of 0.98 (BFDGE) to 5.91 (BADGE·2H2O). Our results suggested that passive diffusion plays a role in the placental transfer of BADGE·HCl·H2O and BFDGE, whereas several mechanisms contribute to the high accumulation of BADGE·2H2O in cord serum. Multiple linear regression analysis indicated significant associations between maternal serum concentrations of BDGEs and blood clinical biomarkers, especially those related to liver injuries, such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and adenosine deaminase (ADA) (P < 0.05). To our knowledge, this is the first study to report the occurrence of BDGEs in paired maternal-fetal serum samples and provide new insights into prenatal and fetal exposures. The newly discovered TTEs in maternal-fetal pairs contribute to a fuller inventory of the transmission activity of pollutants in the human body, ultimately adding to a more significant comprehensive risk evaluation.

Urinary Phenols in Early to Midpregnancy and Risk of Gestational Diabetes Mellitus: A Longitudinal Study in a Multiracial Cohort

Environmental phenols are ubiquitous endocrine disruptors and putatively diabetogenic. However, data during pregnancy are scant. We investigated the prospective associations between pregnancy phenol concentrations and gestational diabetes mellitus (GDM) risk. In a nested matched case-control study of 111 individuals with GDM and 222 individuals without GDM within the prospective PETALS cohort, urinary bisphenol A (BPA), BPA substitutes (bisphenol F and bisphenol S [BPS]), benzophenone-3, and triclosan were quantified during the first and second trimesters. Cumulative concentrations across the two times were calculated using the area under the curve (AUC). Multivariable conditional logistic regression examined the association of individual phenols with GDM risk. We conducted mixture analysis using Bayesian kernel machine regression. We a priori examined effect modification by Asian/Pacific Islander (A/PI) race/ethnicity resulting from the case-control matching and highest GDM prevalence among A/PIs. Overall, first-trimester urinary BPS was positively associated with increased risk of GDM (adjusted odds ratio comparing highest vs. lowest tertile [aORT3 vs. T1] 2.12 [95% CI 1.00-4.50]). We identified associations among non-A/Ps, who had higher phenol concentrations than A/PIs. Among non-A/PIs, first-trimester BPA, BPS, and triclosan were positively associated with GDM risk (aORT3 vs. T1 2.91 [95% CI 1.05-8.02], 4.60 [1.55-13.70], and 2.88 [1.11-7.45], respectively). Triclosan in the second trimester and AUC were positively associated with GDM risk among non-A/PIs (P < 0.05). In mixture analysis, triclosan was significantly associated with GDM risk. Urinary BPS among all and BPA, BPS, and triclosan among non-A/PIs were associated with GDM risk. Pregnant individuals should be aware of these phenols' potential adverse health effects.

Associations of bisphenol exposure with thyroid hormones in pregnant women: a prospective birth cohort study in China

Bisphenols are endocrine disruptor chemicals that disrupt thyroid hormone homeostasis. However, evidence on the effects of bisphenol mixtures on thyroid hormones are insufficient. Therefore, the present study aimed to explore the effects of bisphenol substitutes and bisphenol mixtures on thyroid hormones during pregnancy. The study was conducted among 446 pregnant women in the Guangxi Zhuang Birth Cohort (GZBC), China. In multiple linear regressions, compared with the low-exposure group, bisphenol S (BPS) concentrations in the middle-exposure group led to a 10.90% (95% CI: - 18.16%, - 2.99%) decrease in triiodothyronine (T3) levels in the first trimester; tetrabromobisphenol A (TBBPA) levels in the middle-exposure group led to an 8.26% (95% CI: - 15.82%, - 0.01%) decrease in T3 levels in the first trimester; bisphenol B (BPB) levels in the middle-exposure group led to higher free thyroxine (FT4) levels (9.84%; 95% CI: 1.73%, 18.60%) in the second trimester; bisphenol F (BPF) in the middle-exposure group led to higher FT4 levels (8.59%, 95% CI: 0.53%, 17.31%) in the second trimester; and TBBPA levels in the high-exposure group led to a 9.39% (95% CI: 1.46%, 17.93%) increase in FT4 levels in the second trimester. The Bayesian kernel machine regression (BKMR) and restricted cubic spline (RCS) models showed a U-shaped dose-response relationship between bisphenol A (BPA) and free triiodothyronine (FT3) (p < 0.01) as well as BPS and FT4 (p < 0.05). Nonlinear relationships were also observed between the bisphenol mixture and FT3. Overall, maternal bisphenol exposure affected thyroid hormone levels during pregnancy. This study provides evidence that BPB, BPF, BPS, and TBBPA are unsafe substitutes for BPA, as well as the overall effect of bisphenols on adverse health in human beings.

The First Evidence on the Occurrence of Bisphenol Analogues in the Aqueous Humor of Patients Undergoing Cataract Surgery

Human exposure to BPs is inevitable mostly due to contaminated food. In this preliminary study, for the first time, the presence of bisphenols (BPs) in aqueous humor (AH) collected from 44 patients undergoing cataract surgery was investigated. The measurements were performed using a sensitive ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC−MS/MS). Chromatographic separation was achieved using a reverse-phase column and a gradient elution mode. Multiple reaction monitoring (MRM) was used. The method was validated for bisphenol A (BPA) and bisphenol F (BPF). The limits of quantification (LOQs) of both investigated analytes were 0.25 ng mL−1. The method was linear in the range of 0.25−20.0 ng mL−1 with correlation coefficients (R2) higher than 0.98. Recovery of analytes was in the range of 99.9 to 104.3% and intra-assay and inter-assay precision expressed by relative standard deviations (RSD%) were less than 5%. BPA was detected in 12 AH samples with mean concentrations of 1.41 ng mL−1. BPF was not detected at all. Furthermore, two structural isomers termed BPA-1, and BPA-2 were identified, for the first time, in 40.9% of the AH samples, with almost twice higher mean concentrations of 2.15 ng mL−1, and 2.25 ng mL−1, respectively. The total content of BPs were higher in patients with coexisting ocular pathologies such as glaucoma, age-related macular degeneration (AMD), and diabetes in comparison to cataracts alone. However, the difference between these groups did not reach statistical significance (p > 0.05). Performed investigations indicate the need for further research on a larger population with the aim of knowing the consequences of BPs’ accumulation in AH for visual function.

The development and function of the brain barriers - an overlooked consideration for chemical toxicity

It is well known that the adult brain is protected from some infections and toxic molecules by the blood-brain and the blood-cerebrospinal fluid barriers. Contrary to the immense data collected in other fields, it is deeply entrenched in environmental toxicology that xenobiotics easily permeate the developing brain because these barriers are either absent or non-functional in the fetus and newborn. Here we review the cellular and physiological makeup of the brain barrier systems in multiple species, and discuss decades of experiments that show they possess functionality during embryogenesis. We next present case studies of two chemical classes, perfluoroalkyl substances (PFAS) and bisphenols, and discuss their potential to bypass the brain barriers. While there is evidence to suggest these pollutants may enter the developing and/or adult brain parenchyma, many studies suffer from confounding technical variables which complicates data interpretation. In the future, a more formal consideration of brain barrier biology could not only improve understanding of chemical toxicokinetics but could assist in prioritizing environmental xenobiotics for their neurotoxicity risk.

Last piece in the puzzle of bisphenols BPA, BPS and BPF metabolism: Kinetics of the in vitro sulfation reaction

Bisphenols are endocrine-disrupting chemicals ubiquitously present in the environment, with the consequent exposure to humans. In humans, bisphenols are metabolized to glucuronide and sulfate conjugates. Recent studies indicate that sulfation represents an important bisphenol metabolic pathway for the most vulnerable humans, such as the growing fetus. Our aim was to evaluate sulfation kinetics of commonly detected bisphenols in biological samples: bisphenol A (BPA), bisphenol S (BPS), and bisphenol F (BPF). Furthermore, we evaluated estrogenic agonist potencies and long-term stability of these bisphenol sulfates. BPS and BPF sulfates were prepared by chemical synthesis. Sulfation kinetics of the selected bisphenols were tested in pooled human liver cytosol, as a source for soluble phase II enzymes, including liver sulfotransferases, with quantification by LC-MS/MS. A validated transactivation assay using the hERα-Hela 9903 cell line was used to determine estrogenic agonist potencies. Moreover, BPA, BPS, and BPF sulfate stabilities were examined under various conditions and during storage. In vitro sulfation of BPA and BPS followed Michaelis-Menten kinetics; BPF sulfation followed a substrate inhibition model. Sulfation rates were comparable for these bisphenols, although their K_M values indicated some large differences in affinities. BPA and BPS sulfates are not hERα agonists. The bisphenol sulfates can be considered stable for at least 2 days under these tested media conditions. These data indicate that bisphenol sulfation is an important route in their biotransformation. Compared to glucuronidation, these bisphenols show slower sulfation rates but similar K_M values. BPA and BPS metabolic biotransformation by sulfation provides their detoxification as they are without estrogenic activities.

Maternal perinatal exposure to bisphenol S induces an estrogenic like effect in glucose homeostasis in male offspring

Bisphenol S (BPS) has been introduced into the industry as a safer alternative to bisphenol A (BPA). However, the recent studies have reported a possible association between BPS and disturbed glucose homeostasis, indicating that it may be a risk factor for type 1 and type 2 diabetes mellitus, obesity, and gestational diabetes mellitus. Nevertheless, the role of BPS in glucose metabolism remains controversial. In this study, we investigated the glucose metabolism of male Wistar rats born from dams that were BPS-exposed (groups: BPS-L (0.05 mg/kg/day), BPS-H (20 mg/kg/day)) during pregnancy and lactation. We observed that both BPS treated groups of animals presented a significant decrease in anogenital distance/weight^1/3 , as compared to control animals, although no alterations in testosterone levels were observed. Furthermore, the BPS-L group presented a significant decrease in body weight from postnatal day (PND) 21 to adult stage. In addition, a significant increase in glucose tolerance, pancreatic β-cell proliferation, the frequency of small islets, and the average β-cell size at PND 36 was observed in this group. However, no changes in insulin serum levels and percentage of β-cells were recorded. Furthermore, these changes were not preserved at the adult stage (PND 120). The results suggest that the administration of low doses of BPS during the perinatal period induced an estrogenic like effect, with males apparently becoming more female-like in their responses to a glucose challenge.

Effects of BPA substitutes on the prenatal and cardiovascular systems

Bisphenol A (BPA) is a ubiquitous chemical compound constantly being released into the environment, making it one of the most persistent endocrine-disrupting chemical (EDC) in nature. This EDC has already been associated with developing various pathologies, such as diabetes, obesity, and cardiovascular, renal, and behavioral complications, among others. Therefore, over the years, BPA has been replaced, gradually, by its analog compounds. However, these compounds are structurally similar to BPA, so, in recent years, questions have been raised concerning their safety for human health. Numerous investigations have been performed to determine the effects BPA substitutes may cause, particularly during pregnancy and prenatal life. On the other hand, studies investigating the association of these compounds with the development of cardiovascular diseases (CVD) have been developed. In this sense, this review summarizes the existing literature on the transgenerational transfer of BPA substitutes and the consequent effects on maternal and offspring health following prenatal exposure. In addition, these compounds' effects on the cardiovascular system and the susceptibility to develop CVD will be presented. Therefore, this review aims to highlight the need to investigate further the safety and benefits, or hazards, associated with replacing BPA with its analogs.

Rapid and simultaneous determination of multiple endocrine-disrupting chemicals and their metabolites in human serum and urine samples

Bisphenols, parabens, and their metabolites are a group of chemical compounds with a wide range of polarities but similar chemical structures, which presents a challenge for the simultaneous determination of these compounds in complex biological samples. In this study, a rapid and sensitive method for simultaneous quantification of free bisphenol A (BPA), conjugated BPA, bisphenols, and parabens analogs was developed using solid-phase extraction (SPE) tandem liquid-liquid extraction (LLE). We compared the effects of different types of SPE cartridges, diluents, and LLE solvents on the analyte recovery. Utilizing the direct and indirect determination methods (enzyme hydrolysis), we confirmed the accuracy of the direct method for measuring BPA glucuronide and BPA disulfate. The method enabled the analysis of 24 endocrine-disrupting chemicals (EDCs) in one injection through UHPLC-MSMS measurements, with satisfactory recovery (mean: 91.8-98.6% for urine, 80.2%-96.8% for serum) and precision (RSD <15%). The LOD and LOQ values were 0.003 and 0.01 ng/mL for serum, and 0.002 and 0.006 ng/mL for urine samples, respectively. For real sample analysis, the median concentration of analytes in serum and urine samples ranged from 0.04 ng/mL (BPS) to 56.4 ng/mL (4-HB) and 0.11 ng/mL (BPA) to 136 ng/mL (4-HB), respectively. This method provides a new strategy to simultaneously identify compounds with a wide range of polarities from complicated biological matrices.

Enzyme-Mediated Reactions of Phenolic Pollutants and Endogenous Metabolites as an Overlooked Metabolic Disruption Pathway

It is generally recognized that phenol-containing molecules mainly undergo phase II metabolic reactions, whereas glucuronide and sulfate are conjugated to form water-soluble products. Here, we report direct reactions of phenolic pollutants (triclosan, alkylphenol, bisphenol A [BPA], and its analogues) and some endogenous metabolites (vitamin E [VE] and estradiol) to generate new lipophilic ether products (e.g., BPA-O-VEs and alkylphenol-O-estradiol). A nontargeted screening strategy was used to identify the products in human liver microsome incubations, and the most abundant products (BPA-O-VEs) were confirmed via in vivo exposure in mice. BPA-O-VEs were frequently detected in sera from the general population at levels comparable to those of glucuronide/sulfate-conjugated BPA. Recombinant human cytochrome P450s were applied to find that CYP3A4 catalyzed the formation of these newly discovered ether metabolites by linking the VE hydroxyl group to the BPA phenolic ring, leading to the significantly reduced antioxidative activities of BPA-O-VEs compared to VEs. The effects of the reaction on the homeostasis of reacted biomolecules were finally assessed by in vitro assay and in vivo mice exposures. The generation of BPA-O-VEs decreased the VE concentrations and increased the reactive oxygen species generation after exposure to BPA at environmentally relevant concentrations. The identified reactions provided an overlooked metabolic disruption pathway for phenolic pollutants.

First report on occurrence of bisphenol A isomers in human serum and whole blood

Studies have demonstrated the worldwide presence of bisphenol A (BPA) and its toxic effects on human health. BPA may exist as several structural isomers, which are byproducts in industrial BPA production. However, nearly nothing is known about the occurrence of BPA isomers in human blood and the partitioning of BPA metabolites between human serum and whole blood. In this study, BPA, BPA-sulfate (BPA-S), and BPA-glucuronide (BPA-G) were quantified in 144 pairs of serum and whole blood samples from Chinese participants. BPA was detected in 115 serum and 121 whole blood samples, with mean concentrations of 0.53 and 0.88 ng/mL, respectively. A structural isomer of BPA, tentatively termed B₁-BPA, was identified for the first time, and measurable in 53% and 57% of serum (<LOD-1.9 ng/mL) and whole blood (<LOD-1.4 ng/mL) samples, respectively. BPA-S was the predominant BPA metabolite (mean 2.3 and 1.4 ng/mL, respectively), significantly higher (p < 0.01) than BPA-G (1.3 and 0.64 ng/mL) in both serum and whole blood. The calculated partitioning coefficients between serum and whole blood were the highest for B₁-BPA (mean ± SD, 1.8 ± 0.25), followed by BPA-S (1.6 ± 0.36), BPA-G (1.4 ± 0.37), and BPA (1.3 ± 0.39), indicating their preferential enrichment in the serum fraction. Overall, this study first identifies a BPA isomer, which has not been previously reported in any environmental or human samples. Measuring BPA isomers in human serum and whole blood is critical for accurate human BPA exposure risk assessment.

Autism-Related Transcription Factors Underlying the Sex-Specific Effects of Prenatal Bisphenol A Exposure on Transcriptome-Interactome Profiles in the Offspring Prefrontal Cortex

Bisphenol A (BPA) is an environmental risk factor for autism spectrum disorder (ASD). BPA exposure dysregulates ASD-related genes in the hippocampus and neurological functions of offspring. However, whether prenatal BPA exposure has an impact on genes in the prefrontal cortex, another brain region highly implicated in ASD, and through what mechanisms have not been investigated. Here, we demonstrated that prenatal BPA exposure disrupts the transcriptome-interactome profiles of the prefrontal cortex of neonatal rats. Interestingly, the list of BPA-responsive genes was significantly enriched with known ASD candidate genes, as well as genes that were dysregulated in the postmortem brain tissues of ASD cases from multiple independent studies. Moreover, several differentially expressed genes in the offspring's prefrontal cortex were the targets of ASD-related transcription factors, including AR, ESR1, and RORA. The hypergeometric distribution analysis revealed that BPA may regulate the expression of such genes through these transcription factors in a sex-dependent manner. The molecular docking analysis of BPA and ASD-related transcription factors revealed novel potential targets of BPA, including RORA, SOX5, TCF4, and YY1. Our findings indicated that prenatal BPA exposure disrupts ASD-related genes in the offspring's prefrontal cortex and may increase the risk of ASD through sex-dependent molecular mechanisms, which should be investigated further.

Concentration-dependent transcriptome of zebrafish larvae for environmental bisphenol S assessment

The widespread use of bisphenol S (BPS) as an alternative to bisphenol A has captured attention due to its potential toxicity to aquatic organisms. In the present study, the zebrafish was used as a model to evaluate the toxicity of BPS and determine the underlying mechanisms. The environmental concentration-dependent (0, 0.1, 1, 10, 100, and 1000 μg/L BPS) transcriptome approach was employed in combination with toxicity assays to address the problem. Based on a weighted correlation network analysis, we speculated that excess reactive oxygen species (ROS) may initiate cellular events in BPS-exposed zebrafish, leading to multiple toxic effects. Furthermore, we used pathway enrichment analysis to identify key pathways (MAPK signalling pathway and metabolic pathways) that link the molecular mechanisms with different toxic effects. In addition, we performed protein-protein network and shortest path analyses to identify six hub genes (erbb2, rrm2, rps27a, his2h3c, cdk1, and mcm5) and their interactions. Moreover, we suggest that BPS may interact with erbb2 by molecular docking. Thus, the BPS-erbb2 interaction may activate the MAPK signalling and metabolic pathways, resulting in ROS production and then caused multiple toxic effects in zebrafish. This study provides information for characterising the mechanisms of BPS exposure in aquatic environments.

Interaction of prenatal bisphenols, maternal nutrients, and toxic metal exposures on neurodevelopment of 2-year-olds in the APrON cohort

BACKGROUND

Epidemiological studies suggest that Bisphenol-A (BPA) is a developmental neurotoxicant, but the modifying effects of maternal nutrient status or neurotoxicant metal co-exposures have not been reported. Bisphenol-S (BPS) is being used as a BPA-alternative, but few epidemiological studies have evaluated its effects.

OBJECTIVES

To examine if prenatal maternal BPA or BPS exposure are associated with children's neurodevelopment at two years of age while adjusting for effect-measure modification by sex, maternal nutrients, and co-exposure to neurotoxic metals.

METHODS

Total BPA and BPS concentrations were analyzed in spot maternal urine from the second trimester; metals and maternal nutrient status were analyzed in blood. Child neurodevelopment was evaluated with the Bayley Scales of Infant Development-III (Bayley-III) at age 2 (394 maternal-child pairs) and linear regression was used to investigate associations.

RESULTS

Among nutrients and neurotoxic metals, selenium (Se) and cadmium (Cd) were the most significant predictors of Bayley-III scale scores. Higher maternal Cd was significantly correlated with poorer motor performance (p < 0.01), and higher levels of maternal Se were significantly associated with poorer performance on the cognitive, motor, and adaptive behavior scales (p < 0.05). While maternal Cd did not modify relationships between bisphenol exposures and Bayley-III scores, both maternal Se and child sex were significant effect-measure modifiers. Associations between BPA exposure and social emotional scores were negative for boys (p = 0.056) but positive for girls (p = 0.046). Higher exposure to bisphenols was associated with lower motor scores among children with lower levels of maternal Se.

CONCLUSION

Higher maternal Cd was associated with poorer motor development, but it was not an effect-measure modifier of bisphenols' effects on motor development. Maternal Se may be protective against adverse effects of bisphenols, and additional nutrient-bisphenol interaction studies examining sex-specific effects of BPA and BPS on child development are warranted.

The associations of birth outcome differences in twins with prenatal exposure to bisphenol A and its alternatives

BACKGROUND

Bisphenol A (BPA) and its alternatives, including BPF and BPS, exhibit endocrine disruption activities. However, the effects of bisphenols on fetal growth in twins remain unclear.

OBJECTIVE

To explore the associations of prenatal BPA, BPF, and BPS exposure with birth outcome differences in twins.

METHODS

We recruited 289 twin pregnant women who visited the hospital for prenatal examination during the first trimester from 2013 to 2016. Urinary bisphenol levels were determined during the first, second, and third trimesters. The associations of maternal exposure to bisphenols with birth outcome differences in twins were analyzed after stratification by different trimesters. We applied the multiple informant model to estimate trimester-specific associations between urinary bisphenol concentrations and birth outcome differences in twins.

RESULTS

We found low reproducibility (ICC<0.40) for maternal urinary BPA and moderate reproducibility (0.40 < ICC<0.75) for BPF and BPS. Urinary BPA concentrations were positively associated with within-pair twin birth weight difference when comparing the third vs. the first tertile in each of the three trimesters (i.e., 133.06 g, 95% CI: 68.19, 197.94; 144.5 g, 95%CI: 81.82-207.18 g; and 135.04 g, 95%CI: 71.37-198.71 g for the 1st, 2nd, and 3rd trimester, respectively). The effect of urinary BPA concentration on increased birth length difference within-pair twins were also observed across different trimesters (All P for trends < 0.05). Urinary BPA levels were positively associated with the within-pair birth weight and birth length differences across pregnancy trimesters (All of Type 3 P for values < 0.05).

CONCLUSION

Maternal BPA exposure appeared to influence birth wight and birth length differences in twins. Our results warrant further confirmation.

Comparison of the materno-fetal transfer of fifteen structurally related bisphenol analogues using an ex vivo human placental perfusion model

Regulatory measures and public concerns regarding bisphenol A (BPA) have led to its replacement by a variety of alternatives in consumer products. Due to their structural similarity to BPA, these alternatives are under surveillance, however, for potential endocrine disruption. Understanding the materno-fetal transfer of these BPA-related alternatives across the placenta is therefore crucial to assess prenatal exposure risks. The objective of the study was to assess and compare the placental transfer of a set of 15 selected bisphenols (BPs) (BP 4-4, BPA, BPAF, BPAP, 3-3 BPA, BPB, BPBP, BPC, BPE, BPF, BPFL, BPM, BPP, BPS and BPZ) using the ex vivo human placental perfusion model. The UHPLC-MS/MS method for simultaneous quantification of these BPs in perfusion media, within a concentration range of 0.003-5 μM, was able to measure placenta transfer rates as low as 0.6%-4%. Despite their structural similarities, these BPs differed greatly in placental transport efficiency. The placental transfer rates of BP4-4, BPAP, BPE, BPF, 3-3BPA, BPB, BPA were similar to that of antipyrine, indicating that their main transport mechanism was passive diffusion. By contrast, the placental transfer rates of BPFL and BPS were very limited, and intermediate for BPBP, BPZ, BPC, BPM, BPP and BPAF, suggesting weak diffusional permeability and/or that their passage might involve efflux transport. These placental transfer data will be particularly useful for predicting the fetal exposure of this important class of emerging contaminants.

Comparing effects and action mechanisms of BPA and BPS on HTR-8/SVneo placental cells

Bisphenol A (BPA) is one of the most investigated compound as a suspected endocrine disrupting chemical. It has been found at nM concentrations in the maternal serum, cord serum, and amniotic fluid and also permeates placental tissues. Attempts are being made to replace BPA with the analog Bisphenol S (BPS). Also BPS was found in maternal and umbilical cord serum, and urine samples from a large population of pregnant women. A few studies investigated BPA impact on the placentation process, and even less are available for BPS. This work aimed to elucidate and compare the effects of BPA and BPS on physiological functions of HTR-8/SVneo cells, derived from extravillous trophoblast of first-trimester pregnancy. Proliferation and migration ability of trophoblast cells were assessed in vitro after exposure to BPA or BPS (10-13 - 10-3 M). Further, induction of the inflammatory response by the bisphenols was studied. To provide insight into the molecular pathways implicated in the responses, experiments were carried out in the presence or absence of tamoxifen as estrogen receptors (ERs) blocker, and U0126 as ERK1/2 phosphorylation inhibitor. Data indicate that BPA significantly affects both proliferation and migration of HTR-8/SVneo cells, through ER and ERK1/2 mediated processes. Differently, BPS only acts on proliferation, again through ER and ERK1/2 mediated processes. BPS, but not BPA, induces secretion of interleukins 6 and 8. Such effect is inhibited by blocking ERK1/2 phosphorylation. To the best of our knowledge, these are the first data showing that BPS affects trophoblast functions through ER/MAPK modulation.

The Role of the Bisphenol A in Diabetes and Obesity

Bisphenol A is a compound commonly found in products meant for daily use. It was one of the first compounds to be identified as an endocrine disruptor that was capable of disrupting the endocrine system and producing very similar effects to those of metabolic syndrome. It has recently gained popularity in the scientific arena as a risk factor for obesity and diabetes due to its ability to imitate natural oestrogens and bind to their receptors. The aim was to study the possible relationship between the Bisphenol A endocrine disruptor with diabetes and obesity. The analysis of the articles allows us to conclude that Bisphenol A is an additional risk factor to consider in the development of diabetes and obesity, since it is capable of stimulating the hypertrophy of adipocytes and altering the endocrine system by mimicking the effects of the oestrogen molecule, since epidemiological studies carried out have suggested that the same disruptions seen in experimental studies on animals can be found in humans; however, despite many countries having developed policies to limit exposure to this disruptor in their populations, there is a lack of international agreement. Understanding its relationship with obesity and diabetes will help to raise awareness in the population and adopt public health campaigns to prevent exposure-especially among young people-to these substances.

Metabolic pathways, alterations in miRNAs expression and effects of genetic polymorphisms of bisphenol a analogues: A systematic review

Bisphenol A (BPA) is one of the most common endocrine disruptors found in the environment and its harmful health effects in humans and wildlife have been extensively reported One of the main aims of this review was to examine the metabolic pathways of BPA and BPA substitutes and the endocrine disrupting properties of their metabolites. According to the available literature, phase I and phase II metabolic reactions play an important role in the detoxification process of bisphenols (BPs), but their metabolism can also lead to the formation of highly reactive metabolites. The second part of this work addresses the associations between exposure to BPA and its analogues with the alterations in miRNAs expression and the effects of single nucleotide polymorphisms (SNPs). Available scientific evidence shows that BPs can dysregulate the expression of several miRNAs, and in turn, these miRNAs could be considered as epigenetic biomarkers to prevent the development of a variety of BP-mediated diseases. Interestingly, genetic polymorphisms are able to modify the relationship of BPA exposure with the risk of adverse health effects, suggesting that interindividual genetic differences modulate the susceptibility to the effects of environmental contaminants.

A new LC/MS method for specific determination of human systemic exposure to bisphenol A, F and S through their metabolites: Application to cord blood samples

Due to restriction of the use of BPA, several structural analogues such as BPS and BPF have been proposed for its replacement in many consumer products. This has increased the prevalence of BPS and BPF in urine from tested cohorts. However, these substitutes have similar endocrine disrupting properties to BPA, particularly on reproductive and metabolic functions, which suggests that fetal exposure to these analogues could be of concern for human health. Bisphenols (BPs) are mainly metabolized to glucuronides (BP-Gs), which are considered as inactive but provide a relevant marker of fetal exposure during pregnancy. In most instances, these metabolites are indirectly quantified after hydrolysis and measurement of the corresponding native BPs, which may lead to bias due to spurious BPs contamination during blood collection and/or analyses. We have developed a new method for direct quantification of BP-Gs, which has the advantage of not being affected by errors related to the presence of BPs. First, BP-Gs were extracted from plasma by anion exchange solid phase extraction. They were then labelled with dansyl chloride, using experimentally-optimized incubation conditions, after which the dansyl derivatives were injected into an on-line SPE-UHPLC/MS/MS system. The performance of the method, in terms of sensitivity, precision and accuracy, was evaluated in plasma over a concentration range of 0.05-5 ng/mL. The intra- and inter-day CV% precision were lower than 20% with accuracies ranging from 93% to 115%. The limit of quantification was set at 0.05 ng/mL. The method was then applied to measure BP-Gs in forty-four cord plasma samples. Although no BPF-G was found, BPA-G and BPS-G was determined in almost half of the cord plasma samples with concentration ranges nd-0.089 ng/mL and nd-0.586 ng/mL, respectively.

Investigating the glucuronidation and sulfation pathways contribution and disposition kinetics of Bisphenol S and its metabolites using LC-MS/MS-based nonenzymatic hydrolysis method

Despite showing serious health consequences and widespread exposure, the toxicokinetic information required to evaluate the health risks of BPS is insufficient. Thus, we aim to describe the comprehensive toxicokinetics of BPS and its glucuronide (BPS-G) and sulfate (BPS-S) metabolites in rats. Simultaneous quantification of BPS and its metabolites (authentic standards) was accomplished using UPLC-MS/MS method. BPS displayed rapid absorption, extensive metabolism and fast elimination after oral administration. Following intravenous administration, BPS exhibited CL (8.8 L/h/kg) higher than the rat hepatic blood flow rate suggesting the likelihood of extrahepatic clearance. The CL value differed from those reported previously (sheep and piglets) and the probable reason could be attributed to dose- and/or interspecies differences. BPS was extensively metabolized and excreted primarily through urine as BPS-G (∼56%). BPS and BPS-S exhibited a high protein binding capacity in comparison to BPS-G. In in vitro metabolic stability study, BPS was predominantly metabolized through glucuronidation. The predicted in vivo hepatic clearance of BPS suggested it to be a high and intermediate clearance chemical in rats and humans, respectively. The significant interspecies difference observed in the clearance of BPS between rats and humans indicated that toxicokinetics of BPS should be considered for health risk assessment in humans.

Bisphenol A Inhibits the Transporter Function of the Blood-Brain Barrier by Directly Interacting with the ABC Transporter Breast Cancer Resistance Protein (BCRP)

The breast cancer resistance protein (BCRP) is an important efflux transporter in the blood-brain barrier (BBB), protecting the brain from a wide range of substances. In this study, we investigated if BCRP function is affected by bisphenol A (BPA), a high production volume chemical used in common consumer products, as well as by bisphenol F (BPF) and bisphenol S (BPS), which are used to substitute BPA. We employed a transwell-based in vitro cell model of iPSC-derived brain microvascular endothelial cells, where BCRP function was assessed by measuring the intracellular accumulation of its substrate Hoechst 33342. Additionally, we used in silico modelling to predict if the bisphenols could directly interact with BCRP. Our results showed that BPA significantly inhibits the transport function of BCRP. Additionally, BPA was predicted to bind to the cavity that is targeted by known BCRP inhibitors. Taken together, our findings demonstrate that BPA inhibits BCRP function in vitro, probably by direct interaction with the transporter. This effect might contribute to BPA’s known impact on neurodevelopment.

Oxidative stress-mediated apoptosis is involved in bisphenol S-induced reproductive toxicity in male C57BL/6 mice

The reproductive toxicity of bisphenol S (BPS) in male mammals and its possible mechanism are not clear. We investigated the effects and possible mechanism of action of BPS on adult male C57BL/6 mice. We found that exposure to 200-mg/kg BPS resulted in a significant decrease in the sperm count in the caput/corpus and cauda epididymis, significantly decreased sperm motility, and significantly increased the sperm deformity. Histological evaluation revealed that BPS exposure caused a decrease of spermatozoa in the lumen of seminiferous tubules and a reduction in the proportion of Stage VII or VIII seminiferous tubules in the BPS-treated groups. Furthermore, ultrastructure analysis revealed BPS-induced mitochondrial damage and apoptosis in spermatogenic cells. Moreover, BPS exposure-induced oxidative stress in testicular tissues. Further, dUTP-biotin nick end labeling (TUNEL) assay showed that BPS induced the apoptosis of spermatogenic cells in a dose-dependent manner. BPS also significantly upregulated cleaved caspase-8, cleaved caspase-9, cleaved caspase-3, Fas, and FasL and significantly downregulated the Bcl-2/Bax ratio. These results suggest that BPS-induced oxidative stress in the testis and spermatogenic cell apoptosis potentially impairs spermatogenesis and sperm function, which may be the mechanism of the reproductive toxicity of BPS. The Fas/FasL and mitochondrial signal pathways may be involved in BPS-induced oxidative stress-related apoptosis. These results suggest that BPS-induced oxidative stress in the testis and spermatogenic cell apoptosis potentially impairs spermatogenesis and sperm function, which may be the mechanism of the reproductive toxicity of BPS. The Fas/FasL and mitochondrial signal pathways may be involved in BPS-induced oxidative stress-related apoptosis.