Bisphenol A and Its Analogues in Chinese Total Diets: Contaminated Levels and Risk Assessment

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 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.

Bisphenol A in dairy products, amount, potential risks, and the various analytical methods, a systematic review

This systematic study deals with the amount of bisphenol A (BPA) in milk and dairy products, its analytical methods, and risk assessment. Milk is one of the drinks that has a high consumption. Bisphenol A can be present both in raw milk and its amount undergoes changes during the pasteurization process. This review was conducted by searching for the keywords Bisphenol A, BPA milk, dairy product, cheese, cream, butter, yogurt, measurement, detection, and analysis in different databases. The search was done in three databases, Scopus, PubMed and Science Direct. The largest number of studies on the determination of bisphenol A belonged to Asian and European countries. The amount of bisphenol A in milks was observed in the range from ND to 640 ng/mL. Furthermore, the amount of BPA in the tested cheese samples was observed in the ND range up to 6.1 ng/g and in the yogurt samples in the ND range up to 4.4 ng/g. The most used analytical method was based on liquid chromatography. The most used solvent for extraction was methanol or acetonitrile. HQ (Hazard Quotient) was also calculated in some studies. There was no risk in terms of milk consumption due to BPA contamination in extracted data.

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.

IVIVE-PBPK based new approach methodology for addressing early life toxicity induced by Bisphenol A

Bisphenol A (BPA) is a known endocrine disruptor mimicking natural estrogens with the potential to affect human health, especially during prenatal and postnatal exposure at or below current acceptable daily intake levels. Different adverse effects of BPA are still under investigation, and multiple mechanisms of action remain unexplored. This may be one of the reasons for the continuously changing tolerable daily intake (TDI) of BPA with the emergence of new adverse health effects over time. In addition, translational modelling through in vitro-in vivo extrapolation (IVIVE) can act as prerequisite bridge for translating in-vitro finding into human risk assessment. The objective of this study was to conduct in-vitro experiments and utilize an IVIVE-pregnancy physiologically based pharmacokinetic (P-PBPK) modeling to investigate developmental neurotoxicity and embryotoxicity in humans. The data obtained from human embryonic stem cells-based assays (study conducted between October 2020-2021) were used for the IVIVE-P-PBPK models to obtain the human equivalent doses (HEDs) which were further extrapolated to reference doses (RfDs). The results showed that simulated mean RfDs (μg/kg/day) derived from the HSD3B1 and NFATC2 gene of embryotoxicity and neurodevelopmental toxicity tests, respectively, were 4.94 and 5.18. The simulated RfDs were close to the temporary-tolerable daily intake (t-TDI) recommended by European Food Safety Authority (EFSA) in 2015 (t-TDI: 4 μg/kg·bw) and higher than the TDI of 2023 (0.2 ng/kg·bw). In conclusion, in-vitro toxicogenomics dose-response data combined with PBPK modeling can become a promising alternative new approach methodology (NAM) to support decision-making in chemical risk assessment. Based on the simulated RfDs derived from this NAM, the t-TDI set by EFSA in 2015 may be considered a safe exposure limit for mothers and fetuses at the current BPA intake levels in Chinese mothers. This study provided an animal-free new strategy for NAMs based risk assessment by combining toxicogenomics and computational toxicology.

Neurodevelopmental toxicity of bisphenol AF in zebrafish larvae and the protective effects of curcumin

Bisphenol AF (BPAF) is one of the most commonly used alternatives of bisphenol A in the plastics industry. The effects of BPAF on nervous development are unclear. Curcumin (CUR) has been determined to be an anti-inflammatory and antioxidant agent. In this study, the effects of BPAF on neurotoxicity of zebrafish embryos/larvae and whether CUR could reverse effects induced by BPAF were investigated. The results showed that BPAF treatment induced deficits in locomotor behavior, altered the larval brain development, caused aberrant expression of neurogenesis related genes (elavl3, zn5, α-tubulin, syn2a, and gap43), decreased acetylcholinesterase (AChE) activity, and induced oxidative stress, cell apoptosis, and neuroinflammation in zebrafish larvae. CUR addition could block the adverse effects of BPAF on nervous development by attenuated oxidative stress and cell apoptosis induced by BPAF in zebrafish, enhanced the activity of AChE, and increased the expression of genes involved in the pro-inflammatory cytokines (IL-6, IL-1β, TNF-α, and IL-8). The results of this study indicate that BPAF could induce aberrant development on nervous system. However, CUR exerts neuroprotective effects on BPAF-induced neurotoxicity in zebrafish larvae.

Methodological approaches for the assessment of bisphenol A exposure

Bisphenol A (BPA) is an endocrine disruptor used in food contact materials, by the application of polycarbonate plastics and epoxy resins. The main objective of this study is to compare the estimate of daily BPA exposure at 13 years of age and in the adult Portuguese population, using different methodological approaches, and assess the associations between this exposure and sociodemographic characteristics.

METHODOLOGY

Cross-sectional data of 13-years follow-up from a population-based birth cohort Generation XXI (GXXI) (n = 2804) and from the National Food, Nutrition and Physical Activity Survey (IAN-AF 2015-2016) (n = 3845, ≥18 years old) was used. Dietary information was collected through three food diaries for adolescents and two non-consecutive 24-hour-recalls for adults. To estimate the daily exposure to BPA, three methodological approaches were used. "Food groups attribution" merged the food consumption data with the concentration of BPA in food groups. "Regression tree model" and "random forest" combined food consumption information with urinary BPA, measured in a subsample of 24-hour urine (in adolescents n = 216, and in adults n = 82), both used to predict BPA exposure in the remaining sample. The fit-index of the methodologies was assessed through the root mean square error (RMSE), mean absolute error (MAE) and Spearman correlation coefficient (ρ). Associations between BPA exposure and sociodemographic variables were tested by linear regression models, adjusted for sex, age groups (in adults) and educational level. Tolerable Daily Intake (TDI) of 0.2 ng/kg body weight (bw), recently proposed by the European Food Safety Authority (EFSA), was used for the risk characterization of BPA exposure.

RESULTS

The "random forest" was found as the best methodology to estimate the daily BPA exposure (adolescents: RMSE = 0.989, MAE = 0.727, ρ = 0.168; adults: RMSE = 0.193, MAE = 0.147, ρ = 0.250). The median dietary BPA exposure, calculated by "food groups attribution", was 79.1 and 46.1 ng/kg bw/day for adolescents and adults, respectively, while "random forest" estimated a BPA exposure of 26.7 and 38.0 ng/kg bw/day. 99.9% of the Portuguese population presented a daily exposure above TDI. Male adolescents, females and higher educated adults, were those more exposed to BPA.

CONCLUSIONS

The estimated daily BPA exposure strongly depends on the methodological approach. Food groups attribution may overestimate the exposure while the random forest appears to be a better methodological approach to estimate BPA exposure. Nevertheless, for all methods, the Portuguese population presented an unsafe BPA exposure by largely exceeding the safe levels proposed by EFSA.

Multi-immunoaffinity column for the simultaneous analysis of bisphenol A and its analogues in Chinese foods by liquid chromatography tandem mass spectrometry

Bisphenol A (BPA) and its four analogues have been receiving considerable attention owing to their potential endocrine disrupting effects. The European Food Safety Authority has proposed 0.04 ng/kg·body weight/day of thetemporary tolerable daily intake for BPA. Therefore, a more sensitive analytical method was urgently needed for the necessity of the risk reassessment of bisphenols (BPs). The matrix effect of Chinese foods is a challenge for the analysis of ultra-trace analytes due to the presence of various spices. A multi-immunoaffinity column (mIAC) was prepared for the purification of BPA, BPB, BPF, BPS, and BPAF in Chinese foods following ultra-high-performance liquid chromatography tandem mass spectrometry detection (UHLPC-MS/MS). The recoveries of each of BPs were ranged from 84.6% to 116.7%, and the intra-day precision and inter-day precision were ranged from 1.6% to 12.4%, and from 4.1% to 14.0%, respectively. This is the first report on the mIACs for simultaneous clean-up and analysis of BPs in complex Chinese foods.

Temporal trends in risk of bisphenol A, benzophenone-3 and triclosan exposure among U.S. children and adolescents aged 6-19 years: Findings from the National Health and Nutrition Examination Survey 2005-2016

BACKGROUND

Phenolic compounds with potential adverse health effects are gradually being replaced. Little is known about the potential health risks of BPA, BP3, and TCS exposure in children and adolescents aged 6-19 years in the United States.

OBJECTIVES

To determine trends and rates of change in hazard indices (HI) for three phenolics in U.S. children and adolescents for BPA, BP3, TCS, and to assess changes in gender, race/ethnicity, age, and potential health risks.

METHODS

Metabolic biomonitoring data from field-collected urine samples from the National Health and Nutrition Examination Survey (NHANES) were utilized. Daily intake of three phenols (bisphenol A, benzophenone-3, and triclosan) between 2005 and 2016 in children and adolescents were obtained. Cumulative risk indicators, including hazard quotient (HQ), hazard index (HI), and maximum cumulative ratio (MCR), were used for the health risk assessment of the three phenols.

RESULTS

During this period, the change in LSGM HI was -2.9% per cycle [95% Cl: (-3.7%, -2.2%)], and the percentage of participants with HI > 0.1 decreased from 15.6% to 10.5%. Children (6-11 years) had higher mean HI values than adolescents (12-19 years), while female had higher LSGM HI values than male. MCR values were generally low and negatively correlated with HI. However, the average value of MCR increased from 1.722 to 2.107 during this period.

CONCLUSION

Exposure to phenolics among U.S. children and adolescents has changed in recent decades. However, gaps in data limit the interpretation of trends but legislative activity and advocacy campaigns by nongovernmental organizations may play a role in changing trends. Moreover, there are growing concerns about the potential health risks associated with exposure to multiple phenols in children and adolescents.

In vivo hypoglycemic effects of bisphenol F exposure in high-fat diet mice

Bisphenol F (BPF) is a widely used bisphenol A (BPA) substitute plastic additive that has attracted increasing public concerns due to its potential toxic effects on animal and human health. Although previous studies have indicated that BPF might have harmful effects on metabolic homeostasis, the systematic effects of BPF on glucose disorders remain controversial. In this study, mice fed a normal chow diet (ND) and high-fat diet (HFD) were administered BPF at a dose of 100 μg/kg of body weight, and glucose metabolism was monitored after both short- and long-term treatment. Little change in glucose metabolism was observed in BPF-treated ND mice, but improved glucose metabolism was observed in BPF-treated HFD mice. Consistently, BPF treatment led to increased insulin signalling in the skeletal muscle of HFD mice. Additionally, liver metabolite levels also revealed increased carbohydrate digestion and improved TCA cycle progression in BPF-treated HFD mice. Our results demonstrate that sustained BPF exposure at an environmentally relevant dosage may substantially improve glucose metabolism and enhance insulin sensitivity in mice fed a high-fat diet.

New insights into the effect of bisphenol AF exposure on maternal mammary glands at various stages of gestation in mice

Bisphenol AF (BPAF) is the most estrogenic compound among BPA analogs. Mammary glands (MDs) are special organs that undergo repeated cycles of structural development, metabolism, and functional differentiation. Gestation is a sensitive window for MDs. In the present study, plug-positive CD-1 mice were exposed to vehicle (Veh) or 300 μg/kg BPAF through oral gavage every second day during gestation, and maternal MDs were collected from different developmental windows at 9.5, 13.5, and 18.5 d of gestation (gestation day [GD]9.5, GD13.5 and GD18.5). The results showed that gestational BPAF exposure induced a significantly elevated MD density at GD18.5. Non-target metabolomics analysis was used to screen for tyrosine, valine, ornithine, proline, threonine, phenylalanine and asymmetrical dimethylarginine (ADMA) amino acids, which changed significantly at all time points. Furthermore, the mRNA expression levels of genes related to these amino acids also changed significantly. Additionally, amino acid levels in BPAF-treated MGs at GD18.5 were related to the serum ammonia concentration of the corresponding offspring. These results provide a comprehensive view of the adverse effects of BPAF exposure during gestation on the maternal MG structure and function, which may affect milk components during lactation. Moreover, higher amino acids content may lead to amino acid imbalance or hyperammonemia in newborns.

Adaptation and Resistance: How Bacteroides thetaiotaomicron Copes with the Bisphenol A Substitute Bisphenol F

Bisphenols are used in the process of polymerization of polycarbonate plastics and epoxy resins. Bisphenols can easily migrate out of plastic products and enter the gastrointestinal system. By increasing colonic inflammation in mice, disrupting the intestinal bacterial community structure and altering the microbial membrane transport system in zebrafish, bisphenols seem to interfere with the gut microbiome. The highly abundant human commensal bacterium Bacteroides thetaiotaomicron was exposed to bisphenols (Bisphenol A (BPA), Bisphenol F (BPF), Bisphenol S (BPS)), to examine the mode of action, in particular of BPF. All chemicals caused a concentration-dependent growth inhibition and the half-maximal effective concentration (EC50) corresponded to their individual logP values, a measure of their hydrophobicity. B. thetaiotaomicron exposed to BPF decreased membrane fluidity with increasing BPF concentrations. Physiological changes including an increase of acetate concentrations were observed. On the proteome level, a higher abundance of several ATP synthase subunits and multidrug efflux pumps suggested an increased energy demand for adaptive mechanisms after BPF exposure. Defense mechanisms were also implicated by a pathway analysis that identified a higher abundance of members of resistance pathways/strategies to cope with xenobiotics (i.e., antibiotics). Here, we present further insights into the mode of action of bisphenols in a human commensal gut bacterium regarding growth inhibition, and the physiological and functional state of the cell. These results, combined with microbiota-directed effects, could lead to a better understanding of host health disturbances and disease development based on xenobiotic uptake.

Bisphenol S exposure induces intestinal inflammation: An integrated metabolomic and transcriptomic study

As a typical substitute for bisphenol A (BPA), bisphenol S (BPS) is raising concerns due to the potential adverse effects on human health. Limit evidence is available to understand the toxicity of BPS to the digestive system, especially for intestine. In this study, we aimed to investigate the potential effects and underlying mechanisms of BPS exposure on human colon mucosal epithelial cells (NCM460). Our results showed that BPS exposure significantly increased the production of pro-inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ) and interleukin-17A (IL-17A). The tight junctions of the cells has been destroyed by BPS exposure, which was characterized by a down-regulation of the tight junction proteins (Claudin1 and zonula occluden 1 (ZO1)). A multi-omics study explored the underlying mechanisms based on the metabolomic and transcriptomic responses. A variety of neurotransmitters increased significantly after exposure to BPS. The top enriched pathway was "glutamatergic synapse", which was activated by BPS exposure, resulting in the up-regulation of l-glutamine. Links were observed among the altered metabolites, genes and cytokines. Our results indicate that exposure to BPS may disturb the balance of gut-brain axis, leading to the production of inflammatory cytokines and the destruction of tight junction in NCM460 cells. It provides new clue for the development of intestinal inflammation in terms of the environmental pollutants.

Effects of genetic polymorphisms in body mass index according to dietary exposure to bisphenols and parabens

A growing body of evidence supports that more than 900 single nucleotide polymorphisms (SNPs) and exposure to endocrine disrupting chemicals, such as bisphenols and parabens, are important contributors to the development of obesity. The aim of this study was to evaluate the way in which fat mass and obesity-associated gene (FTO) rs9939609 and leptin receptor (LEPR) rs9436303 variants contribute to variability in body mass index (BMI) according to estimated dietary exposure of bisphenols and parabens. This cross-sectional study included 101 Spanish participants (16-24 years). SNP genotyping assays were performed through quantitative PCRs (qPCRs) using Taqman® probes. Dietary exposure to bisphenols and parabens was calculated from food frequency questionnaire and chemical determination in food samples by ultra-high performance liquid chromatography-tandem mass spectrometry system. Linear regression models were conducted to address the association of genetic variants and BMI according to levels of bisphenols/parabens exposure. Risk G allele of LEPR rs9436303 was significantly positively associated with BMI (exp (β) = 1.20, 95% CI: 1.04-1.38, p = 0.011). In participants highly exposed to bisphenols, the LEPR rs9436303 G allele was related to a significant increased BMI (exp (β) = 1.27, 95% CI: 1.03-1.57, p = 0.024). A more relevant trend was observed with high exposure to parabens (exp (β) = 1.33, 95% CI: 1.08-1.63, p = 0.009). We provide the first evidence that interaction between LEPR polymorphism and dietary intake of bisphenols and parabens may be responsible for an increased BMI, suggesting a potential effect in obesity. Moreover, we proposed LEPR rs9436303 as a genetic marker of susceptibility to excess weight induced by exposure.

Determination of Parabens, Bisphenol A and Its Analogs, Triclosan, and Benzophenone-3 Levels in Human Urine by Isotope-Dilution-UPLC-MS/MS Method Followed by Supported Liquid Extraction

The development of a rapid analytical approach for determining levels of antibacterial agents, plasticizers, and ultraviolet filters in biosamples is crucial for individual exposure assessment. We developed an analytical method to determine the levels of four parabens—bisphenols A (BPA) and its analogs, triclosan (TCS), triclocarban, and benzophenone-3 (BP-3)—in human urine. We further measured the levels of these chemicals in children and adolescents. We used a supported liquid extraction (SLE) technique coupled with an isotope-dilution ultraperformance liquid chromatography-tandem mass spectrometry (ID-UPLC-MS/MS) method to assess the detection performance for these chemicals. Forty-one urine samples from 13 children and 28 adolescents were assessed to demonstrate the capability and feasibility of our method. An acceptable recovery (75.6–102.4%) and matrix effect (precision < 14.2%) in the three-level spiked artificial urine samples were achieved, and good performance of the validated ID-UPLC-MS/MS method regarding linearity, limits of detection, and quantitation was achieved. The within-run and between-run accuracy and precision also demonstrated the sensitivity and stability of this analytical method, applied after SLE. We concluded that the ID-UPLC-MS/MS method with SLE pretreatment is a valuable analytical method for the investigation of urinary antibacterial agents, plasticizers, and ultraviolet filters in humans, useful for human biomonitoring.

Exposure to Bisphenolic Analogues in the Sixth Total Diet Study — China, 2016–2019

What is already known about this topic?

Bisphenol A (BPA) and other bisphenolic compounds (BPs) are proved to pose potential endocrine disrupting properties. The primary source of BP exposure is the diet. European Food Safety Authority (EFSA) established a temporary tolerable daily intake (t-TDI) of BPA 4 μg/kg body weight per day.

What is added by this report?

BPs were detected in composite food samples from the Sixth China Total Diet Study (TDS) at percentages of 27.1%–78.5%. The estimated dietary exposure of BPA and bisphenol S (BPS) for an average adult were 18.1 ng/kg body weight per day and 22.2 ng/kg body weight per day, respectively. The main dietary contributors for BPs were cereals, water and beverage, meat as well as vegetables.

What are the implications for public health practices?

BP dietary intake poses low risks on the Chinese general population based on the t-TDI set by EFSA. BPS presented a higher exposure level than BPA, which highlights the need to strengthen the surveillance of BP alternatives in foodstuffs.