Comparison of toxicokinetic properties of eleven analogues of Bisphenol A in pig after intravenous and oral administrations

Exposure characteristics and cumulative risk assessment of bisphenol A and its substitutes: the Taiwan environmental survey for toxicants 2013

Introduction

Ever since the use of bisphenol A (BPA) has been restricted, concerns have been raised regarding the use of its substitutes, such as bisphenol S (BPS) and bisphenol F (BPF). Meanwhile, the EU European Food Safety Authority (EFSA) issued the new tolerable daily intake (TDI) after the latest re-risk assessment for BPA, which enforced the need for cumulative risk assessment in the population. This study was conducted to identify BPA and its substitute's exposure characteristics of the general Taiwanese population and estimate the cumulative risk of bisphenol exposure.

Methods

Urine samples (N = 366 [adult, 271; minor, 95]) were collected from individuals who participated in the Taiwan Environmental Survey for Toxicants 2013. The samples were analyzed for BPA, BPS, and BPF through ultraperformance liquid chromatography-tandem mass spectrometry. Daily intake (DI) levels were calculated for each bisphenol. Hazard quotients (HQs) were calculated with the consideration of tolerable DI and a reference dose. Additionally, hazard index (HI; sum of HQs for each bisphenol) values were calculated.

Results

Our study found that the median level of BPA was significantly higher in adults (9.63 μg/g creatinine) than in minors (6.63 μg/g creatinine) (p < 0.001). The DI of BPS was higher in female (0.69 ng/kg/day) than in male (0.49 ng/kg/day); however, the DIs of BPF and BPS were higher in boys (1.15 and 0.26 ng/kg/day, respectively) than in girls (0.57 and 0.20 ng/kg/day, respectively). Most HI values exceeded 1 (99% of the participants) after EFSA re-establish the TDI of BPA.

Discussion

Our study revealed that the exposure profiles and risk of BPA and its substitute in Taiwanese varied by age and sex. Additionally, the exposure risk of BPA was deemed unacceptable in Taiwan according to new EFSA regulations, and food contamination could be the possible source of exposure. We suggest that the risk of exposure to BPA and its substitutes in most human biomonitoring studies should be reassessed based on new scientific evidence.

The Conflict between Regulatory Agencies over the 20,000-Fold Lowering of the Tolerable Daily Intake (TDI) for Bisphenol A (BPA) by the European Food Safety Authority (EFSA)

BACKGROUND

The European Food Safety Authority (EFSA) recommended lowering their estimated tolerable daily intake (TDI) for bisphenol A (BPA) 20,000-fold to 0.2  ng / kg  body weight  ( BW ) / day . BPA is an extensively studied high production volume endocrine disrupting chemical (EDC) associated with a vast array of diseases. Prior risk assessments of BPA by EFSA as well as the US Food and Drug Administration (FDA) have relied on industry-funded studies conducted under good laboratory practice protocols (GLP) requiring guideline end points and detailed record keeping, while also claiming to examine (but rejecting) thousands of published findings by academic scientists. Guideline protocols initially formalized in the mid-twentieth century are still used by many regulatory agencies. EFSA used a 21st century approach in its reassessment of BPA and conducted a transparent, but time-limited, systematic review that included both guideline and academic research. The German Federal Institute for Risk Assessment (BfR) opposed EFSA's revision of the TDI for BPA.

OBJECTIVES

We identify the flaws in the assumptions that the German BfR, as well as the FDA, have used to justify maintaining the TDI for BPA at levels above what a vast amount of academic research shows to cause harm. We argue that regulatory agencies need to incorporate 21st century science into chemical hazard identifications using the CLARITY-BPA (Consortium Linking Academic and Regulatory Insights on BPA Toxicity) nonguideline academic studies in a collaborative government-academic program model.

DISCUSSION

We strongly endorse EFSA's revised TDI for BPA and support the European Commission's (EC) apparent acceptance of this updated BPA risk assessment. We discuss challenges to current chemical risk assessment assumptions about EDCs that need to be addressed by regulatory agencies to, in our opinion, become truly protective of public health. Addressing these challenges will hopefully result in BPA, and eventually other structurally similar bisphenols (called regrettable substitutions) for which there are known adverse effects, being eliminated from all food-related and many other uses in the EU and elsewhere. https://doi.org/10.1289/EHP13812.

A biochemical and histological evaluation of in vivo exposure of bisphenol P for multi-organ toxicity and pathology in rats

Bisphenol P (BPP) is a structural analog of bisphenol A (BPA) and is increasingly used as a substitute of BPA in commercial and household applications. In recent years, BPP has been frequently detected in terrestrial and aquatic ecosystems. Very little epidemiological and experimental information are available on the toxicity potential of BPP in human and animal systems, which is very concerning in view of its increasing use. The current study evaluated the biochemical and histopathological effects of BPP in rats. The seven experimental groups (n = 5 rats/group) included BPA5 (5 mg), BPA50 (50 mg), BPA100 (100 mg), BPP5 (5 mg), BPP50 (50 mg), and BPP100 (100 mg) while the remaining one group served as untreated control. At the end of treatment, the organs (liver, kidney, heart, and lung) of rats were harvested for oxidative stress and histopathological analyses. A significant (p < .05) decrease was observed in the weight of the liver, lungs, and kidneys in the BPP100 group similar to the BPA100 group compared with the control group. Further, a significant (p < .05) decrease was also observed for concentrations of antioxidant enzymes (catalase, peroxidase, superoxide dismutase, and glutathione peroxidase) in the liver, lungs, kidneys, and heart at the highest two doses of BPP similar to the respective BPA groups compared with the control group. The two highest doses of BPP induced histopathological changes in the liver such as nuclei distortion, excessive necrosis of hepatocytes, nuclei shrinkage and pyknosis of cells with disrupted cell structure (BPP100), and cellular congestion and degeneration of hepatocytes (BPP50) similar to the two respective doses of BPA. The BPP treated groups also showed varying histopathological changes in kidney tissue, heart tissue, and lung tissue similar to BPA treated rats. In conclusion, the present study indicated that BPP has the potential to induce oxidative stress and alter the histomorphological architecture of different organs and is as deleterious as BPA.

Mixture Effects of Bisphenol A and Its Structural Analogs on Estrogen Receptor Transcriptional Activation

Bisphenol A (BPA) exposure has been widely linked to endocrine-disrupting effects. Recently, many substitutes for BPA have been developed as safe structural analogs. However, they have still been reported to have similar adverse effects. The current study evaluated the effects of bisphenol A and eight structural analogs on the transcription of estrogen receptor alpha (ERα). The effects of binary and ternary mixtures prepared from different combinations of BPA analogs were also evaluated for transcription activity. The measured data of the mixtures were compared to the predicted data obtained by the full logistic model, and the model deviation ratio (MDR) was calculated to determine whether the effects were synergistic, antagonistic, or additive. Overall, the results suggest that the effect of bisphenol compound are additive in binary and ternary mixtures.

Boron nitride quantum dots-enhanced laser desorption/ionization mass spectrometry analysis and imaging of bisphenol A

Bisphenol A (BPA) displays harmful effects on the human health, including potent endocrine activity and potential impact on the development of cancer. Analysis BPA residues in water and plastic products attracted considerable attention in the past decades. However, dominantly used conventional analysis techniques are unable to directly and non-destructively identify the correct species of BPA in plastic products. Hence, this study demonstrates the effective utilisation of boron nitride quantum dots (BNQDs) as an inorganic matrix in matrix-assisted laser desorption/ionization mass spectrometry analysis and imaging (MALDI-MS & MSI) for BPA. The presence of abundant hydroxyl and amino groups on the BNQDs' surface is favourable for the formation of hydrogen bonds with BPA, and increases their ionization and chemoselectivity. Intriguingly, the BNQDs matrix offers a distinct signal for phenolic hazardous molecules featuring different hydroxyl groups. The method was applied to detect BPA at nanomolar level in environmental water, and also allowed non-destructive and in situ mapping of BPA in plastics and pacifiers. This research provides a novel strategy for adapting nanomaterials as inorganic matrices for analysis of small molecular pollutants in environmentally relevant samples using MALDI-MS & MSI.

Obesogenic effect of Bisphenol P on mice via altering the metabolic pathways

Bisphenol P (BPP), structurally similar to bisphenol A, is commonly identified in the samples of environment, food, and humans. Unfortunately, very little information is currently available on adverse effects of BPP. The obesogenic effects and underlying mechanisms of BPP on mice were investigated in this study. Compared with the control, high-resolution microcomputed tomography (micro-CT) scans displayed that the visceral fat volume of mice was significantly increased at a dose of 5 mg/kg/day after BPP exposure for 14 days, whereas the subcutaneous fat volume remained unchanged. Nontargeted metabolomic analysis revealed that BPP significantly perturbed the metabolic pathways of mouse livers, and acetyl-CoA was identified as the potential key metabolite responsible for the visceral fat induced by BPP. These findings recommend that a great deal of attention should be paid to the obesogenic properties of BPP as a result of its widely utilized and persistence in the environment.