Ten bisphenol analogues in Chinese fresh dairy milk: high contribution ratios of conjugated form, importance of enzyme hydrolysis and risk evaluation

Effect of Bisphenol F on Reproductive Function in F1 Generation Male Mice and its Potential Mechanisms

Bisphenol F (BPF) is an environmental endocrine disruptor capable of crossing the placental barrier and affecting the growth and development of offspring. Despite its potential impact, systematic research about effects of BPF on the reproductive function of male offspring remains limited. In this study, pregnant female mice were exposed to BPF at doses of 40, 400, and 4000 μg/kg during gestation and lactation, respectively, to evaluate its impact on testicular damage, testosterone levels, and spermatogenesis of male offspring (F1 generation), and further explore the mechanisms using transcriptomics. First, the study demonstrated that BPF induces testicular damage in F1 generation mice, leading to decreased testosterone levels and sperm quality. Second, transcriptomic analysis revealed that BPF affected spermatogenesis in F1 generation mice by disrupting retinol metabolism. Third, transcriptomic analysis revealed that BPF reduce the capacity for testosterone synthesis in F1 generation mice by diverting the testosterone precursor dehydroepiandrosterone (DHEA) towards the synthesis of 16α-hydroxydehydroepiandrosterone rather than testosterone. Finally, it was confirmed that BPF hinder cholesterol transport to mitochondria by inhibiting the cAMP signaling pathway, thereby impacting testosterone synthesis. In summary, the results of this study suggest that gestational exposure to BPF can lead to reproductive dysfunction in F1 generation male mice.

Bisphenol AP inhibits mouse oocyte maturation in vitro by disrupting cytoskeleton architecture and cell cycle processes

Bisphenol A (BPA) is among the extensively researched environmental endocrine-disrupting chemicals (EDCs), and its utilization is restricted owing to the detrimental impacts it has on human health. Bisphenol AP (BPAP) is one of the alternatives to BPA, but the influence of BPAP on human health has not been elucidated. The objective of the current research was to determine the influence of BPAP exposure on the in vitro maturation of mouse oocytes and to explore its potential reproductive toxicity. BPAP exposure was found to inhibit polar body extrusion during mouse oocyte maturation, resulting in an arrest at the metaphase I stage of meiosis. Exposure to BPAP led to sustained activation of BubR1, preventing the degradation of both Securin and Cyclin B1. Mechanistically, BPAP exposure disrupts spindle assembly and chromosome alignment. Levels of acetylated α-tubulin were significantly elevated in BPAP-treated oocytes, reflecting decreased spindle stability. Exposure to BPAP also induced DNA damage and impaired DNA damage repair. In addition, BPAP exposure altered histone modification levels. In summary, this investigation suggests that exposure to BPAP can influence cytoskeletal assembly, interfere with cell cycle progression, induce DNA damage, alter histone modifications, and ultimately impede oocyte meiotic maturation. This investigation enhances understanding of the impact of bisphenol analogs on female gametes, underscoring that BPAP cannot be considered a reliable replacement for BPA.

Dietary bisphenols exposure as an influencing factor of body mass index

BACKGROUND

Over the past three decades, there has been a significant increase in the prevalence and incidence of overweight and obesity worldwide. The obesogen hypothesis suggests that certain external agents may affect pathways related to fat accumulation and energy balance by stimulating fat cell differentiation and proliferation. Previous research has indicated that exposure to bisphenol A (BPA) and some of its analogues may influence fat accumulation by promoting the transformation of preadipocytes into adipocytes. This study aimed to assess the possible contribution of dietary bisphenol exposure to the odds of developing overweight and obesity in a sample of Spanish children according to sex.

METHODS

Dietary and anthropometric data were collected from 179 controls and 124 cases schoolchildren aged 3-12 years. Dietary exposure to BPA and bisphenol S (BPS) was assessed using a food consumption frequency questionnaire. Logistic regression models were used to assess the influence of dietary exposure to bisphenols on overweight and obesity stratified by sex.

RESULTS

For females, cases had significantly higher exposure to BPA from meat and eggs compared to controls (median = 319.55, interquartile range (IQR) = 176.39-381.01 vs 231.79 (IQR) = 162.11-350.19, p-value = 0.046). Diet quality was higher for controls (6.21 (2.14) vs 4.80 (2.24) p < 0.001) among males independently of a high or low exposure to bisphenols. However, higher diet quality was observed for female controls with an high exposure of total bisphenols (6.79 (2.04) vs 5.33 (2.02) p = 0.031). Females exposed to high levels of BPA from meat and eggs had higher likelihood of being overweight and obese (adjusted Odds Ratio = 2.70, 95% confidence interval = 1.00 - 7.32). However, no consistent associations were found in males.

CONCLUSIONS

High BPA levels from meat and eggs were positively associated with overweight and obesity in females. The dietary intake of BPA in the schoolchildren in the present study was much higher than the acceptable daily intake established by EFSA for the last year.

Adverse outcomes of the newly emerging bisphenol A substitutes

BPA and its analogues are facing increasingly stringent regulations restricting their use due to the increasing knowledge of their harmful effects. It is therefore expected that novel BPA analogues and alternatives will replace them in plastic products, cans and thermal paper to circumvent restrictions imposed by legislation. This raises concerns about the safety of "BPA-free" products, as they contain BPA substitutes whose safety has not been sufficiently assessed prior to their market introduction. The regulatory agencies have recognised BPAP, BPBP, BPC2, BPE, BPFL, BPG, BPP, BPPH, BPS-MAE, BPS-MPE, BP-TMC, BPZ and the alternatives BTUM, D-90, UU and PF201 as compound with insufficient data regarding their safety. We demonstrate that the mentioned compounds are present in consumer products, food and the environment, thus exhibiting toxicological risk not only to humans, but also to other species where their toxic effects have already been described. Results of in silico, in vitro and in vivo studies examining the endocrine disruption and other effects of BPA analogues show that they disrupt the endocrine system by targeting various nuclear receptors, impairing reproductive function and causing toxic effects such as hepatotoxicity, altered behaviour and impaired reproductive function. In vitro and in vivo data on BPA alternatives are literally non-existent, although these compounds are already present in commonly used thermal papers. However, in silico studies predicted that they might cause adverse effects as well. The aim of this article is to comprehensively collate the information on selected BPA substitutes to illustrate their potential toxicity and identify safety gaps.

Feasibility of sulfated BPA and BPS as wastewater-based epidemiology biomarkers: Insights from wastewater and reported human urine analysis

In wastewater-based epidemiology (WBE), the selection of appropriate biomarkers presents a significant challenge. Recently, sulfated bisphenols have garnered attention as potential WBE biomarkers due to their increased stability in wastewater compared to glucuronide conjugates. This study aims to comprehensively assess the feasibility of employing sulfated BPA and BPS as WBE biomarkers by analyzing both WBE and human biomonitoring data. To conduct this research, wastewater samples were collected from six domestic wastewater treatment plants in Guangzhou, China, and urinary concentration of BPA and BPS were obtained from peer-reviewed literature. The results revealed that mean urinary concentrations of BPA and BPS, calculated using Monte Carlo simulations, significantly exceeded those reported in human biomonitoring studies. Furthermore, the per capita mass load ratio of sulfated BPA and BPS in human urine to the mass load in wastewater was found to be below 10 %. This outcome suggests that the excretion of BPA-S and BPS-S in urine does not make a substantial contribution to wastewater, hinting at the existence of other notable sources. Consequently, our study concludes that sulfated BPA-S and BPS-S are not suitable candidates as WBE biomarkers. This work provides a referenceable analytical framework for evaluating the feasibility of WBE biomarkers and emphasizes the necessity for caution when utilizing WBE to assess human exposure to chemicals.

Deciphering the mechanisms and interactions of the endocrine disruptor bisphenol A and its analogs with the androgen receptor

Bisphenol A (BPA) and its various forms used as BPA alternatives in industries are recognized toxic compounds and antiandrogenic endocrine disruptors. These chemicals are widespread in the environment and frequently detected in biological samples. Concerns exist about their impact on hormones, disrupting natural biological processes in humans, together with their negative impacts on the environment and biotic life. This study aims to characterize the interaction between BPA analogs and the androgen receptor (AR) and the effect on the receptor's normal activity. To achieve this goal, molecular docking was conducted with BPA and its analogs and dihydrotestosterone (DHT) as a reference ligand. Four BPA analogs exhibited higher affinity (-10.2 to -8.7 kcal/mol) for AR compared to BPA (-8.6 kcal/mol), displaying distinct interaction patterns. Interestingly, DHT (-11.0 kcal/mol) shared a binding pattern with BPA. ADMET analysis of the top 10 compounds, followed by molecular dynamics simulations, revealed toxicity and dynamic behavior. Experimental studies demonstrated that only BPA disrupts DHT-induced AR dimerization, thereby affecting AR's function due to its binding nature. This similarity to DHT was observed during computational analysis. These findings emphasize the importance of targeted strategies to mitigate BPA toxicity, offering crucial insights for interventions in human health and environmental well-being.

Bisphenol Z exposure inhibits oocyte meiotic maturation by rupturing mitochondrial function

The use of bisphenol A (BPA) has been restricted due to its endocrine-disrupting effects. As a widely used alternative to BPA today, environmental levels of bisphenol Z (BPZ) continue to rise and accumulate in humans. Oocyte quality is critical for a successful pregnancy. Nevertheless, the toxic impacts of BPZ on the maturation of mammalian oocytes remain unexplored. Therefore, the impacts of BPZ and BPA on oocyte meiotic maturation were compared in an in vitro mouse oocyte culture model. Exposure to 150 μM of both BPZ and BPA disrupted the assembly of the meiotic spindle and the alignment of chromosomes, and BPZ exerted stronger toxicological effects than BPA. Furthermore, BPZ resulted in aberrant expression of F-actin, preventing the formation of the actin cap. Mechanistically, BPZ exposure disrupted the mitochondrial localization pattern, reduced mitochondrial membrane potential and ATP content, leading to impaired mitochondrial function. Further studies revealed that BPZ exposure resulted in oxidative stress and altered expression of genes associated with anti-oxidative stress. Moreover, BPZ induced severe DNA damage and triggered early apoptosis in oocytes, accompanied by impaired lysosomal function. Overall, the data in this study suggest that BPZ is not a safe alternative to BPA. BPZ can trigger early apoptosis by affecting mitochondrial function and causing oxidative stress and DNA damage in oocytes. These processes disrupt cytoskeletal assembly, arrest the cell cycle, and ultimately inhibit oocyte meiotic maturation.

Associations of Bisphenols Exposure and Hyperuricemia Based on Human Investigation and Animal Experiments

Hyperuricemia is characterized by elevated blood uric acid (UA) levels, which can lead to certain diseases. Epidemiological studies have explored the association between environmental contaminant exposure and hyperuricemia. However, few studies have investigated the role of chemical exposure in the development of hyperuricemia. Here, we sought to investigate the effects of bisphenol exposure on the occurrence of hyperuricemia. Fifteen bisphenol chemicals (BPs) were detected in human serum and urine samples collected from an area with a high incidence of hyperuricemia in China. Serum UA levels positively correlated with urinary bisphenol S (BPS), urinary bisphenol P (BPP), and serum bisphenol F (BPF). The effects of these three chemicals on UA levels in mice were explored at various exposure concentrations. An increase in serum UA levels was observed in BPS- and BPP-exposed mice. The results showed that BPS exposure increased serum UA levels by damaging the structure of the kidneys, whereas BPP exposure increased serum UA levels by disturbing purine metabolism in the liver. Moreover, BPF did not induce an increase in serum UA levels owing to the inhibition of guanine conversion to UA. In summary, we provide evidence of the mechanisms whereby exposure to three BPs disturbs UA homeostasis. These findings provide new insights into the risks of exposure to bisphenol chemicals.

Bisphenol analogues in infant foods in south China and implications for infant exposure

Bisphenol analogues (BPs) are commonly used as modifiers, stabilizers and photo-initiators in polymer materials, including those used in food packaging. Compared to adults, infants are more sensitive to chemicals because their bodies are growing and not fully developed. Therefore, it is essential to determine the concentrations of BPs in common infant foods to assess infant exposure and prevent hazards. We collected 54 infant formula (IF) samples, 90 complementary food (CMF) samples and 62 breastmilk samples from breastfeeding women in south China. Tandem mass spectrometry coupled to liquid chromatography separation (HPLC-MS/MS) was used to detect the concentrations of 8 BPs in the three types of food samples. The estimated daily intake (EDI) of infants was also assessed. The results showed that the detection frequency of bisphenol F (BPF), bisphenol S (BPS), bisphenol AF (BPAF) and bisphenol AP (BPAP) were relatively high among the different infant foods. BPF, BPP and BPS were predominant among the detected BPs. The lowest 95th EDI for BPA was 0.67 ng kg-bw-1 day-1, exceeding the tolerable daily intake (TDI) limit for BPA set by the European Food Safety Authority in 2023. Thus, BP exposure is a significant risk to infants. More attention should be paid to the presence of BPs in daily use products and food, and intake limits should be set for BPs other than BPA.

Invisible Hand behind Female Reproductive Disorders: Bisphenols, Recent Evidence and Future Perspectives

Reproductive disorders are considered a global health problem influenced by physiological, genetic, environmental, and lifestyle factors. The increased exposure to bisphenols, a chemical used in large quantities for the production of polycarbonate plastics, has raised concerns regarding health risks in humans, particularly their endocrine-disrupting effects on female reproductive health. To provide a basis for future research on environmental interference and reproductive health, we reviewed relevant studies on the exposure patterns and levels of bisphenols in environmental matrices and humans (including susceptible populations such as pregnant women and children). In addition, we focused on in vivo, in vitro, and epidemiological studies evaluating the effects of bisphenols on the female reproductive system (the uterus, ovaries, fallopian tubes, and vagina). The results indicate that bisphenols cause structural and functional damage to the female reproductive system by interfering with hormones; activating receptors; inducing oxidative stress, DNA damage, and carcinogenesis; and triggering epigenetic changes, with the damaging effects being intergenerational. Epidemiological studies support the association between bisphenols and diseases such as cancer of the female reproductive system, reproductive dysfunction, and miscarriage, which may negatively affect the establishment and maintenance of pregnancy. Altogether, this review provides a reference for assessing the adverse effects of bisphenols on female reproductive health.

Simultaneous determination of twelve natural estrogens in dairy milk using liquid-liquid extraction and solid-phase extraction coupled with gas chromatography-mass spectrometry

There have been many analytical methods for natural estrogens in commercial dairy milk samples, but in most of which, only four major estrogens (estrone (E1), 17β-estradiol (E2), estriol (E3), and 17α-estradiol (αE2)) were included. This work developed an effective GC-MS analytical method for simultaneous analysis of twelve natural estrogens in commercial dairy milk sample, in which eight far-less well-known natural estrogens (2-hydroxyestone (2OHE1), 4-hydroxyestrone (4OHE1), 2-hydroxyestradiol (2OHE2), 4-hydroxyestradiol (4OHE2), 16-epiestriol (16epiE3), 16α-hydroxyestrone (16αOHE1), 16-ketoestradiol (16ketoE2) and 17epiestriol (17epiE3)) were included besides the four major natural estrogens. With liquid-liquid extraction and solid phase extraction, twelve natural estrogens in commercial dairy milk could be effectively extracted. The established method showed good linearity (R2 > 0.9991), low limits of detections (LODs, 0.02-0.11 ng/g), as well as excellent recoveries (64-117%) with satisfactory low relative standard deviations (RSDs, 0.8-14.7%). This established method was applied to seven commercial dairy milk samples, and all the twelve natural estrogens were frequently detected except for 4OHE2 without detection in any sample. Our results showed that the concentration contribution ratios of the eight far-less well-known natural estrogens in commercial dairy milk samples contributed to 32-83%, while the corresponding contribution ratios based on estrogen equivalence (EEQ) were 21-62%. This work highlighted the high abundance of the eight far-less well-known natural estrogens in commercial dairy milk based on both concentration and EEQ, which has been neglected for a long time.