Human Health Effects of Bisphenol A

An overview of the occurrence, fate, and human risks of the bisphenol-A present in plastic materials, components, and products

With over 95% of bisphenol-A (BPA) used in the production of polycarbonate (PC) and epoxy resins, termed here as BPA-based plastic materials, components, and products (MCPs), an investigation of human exposure to BPA over the whole lifecycle of BPA-based plastic MCPs is necessary. This mini-review unpacks the implications arising from the long-term human exposure to BPA and its potential accumulation across the lifecycle of BPA-based plastics (production, use, and management). This investigation is timely and necessary in promoting a sustainable circular economy model. Restrictions of BPA in the form of bans and safety standards are often specific to products, while safety limits rely on traditional toxicological and biomonitoring methods that may underestimate human health implications and therefore the "safety" of BPA exposure. Controversies in regards to the: (a) dose-response curves; (b) the complexity of sources, release mechanisms, and pathways of exposure; and/or (c) the quality and reliability of toxicological studies, appear to currently stifle progress toward the regulation of BPA-based plastic MCPs. Due to the abundance of BPA in our MCPs production, consumption, and management systems, there is partial and inadequate evidence on the contribution of BPA-based plastic MCPs to human exposure to BPA. Yet, the production, use, and end-of-life management of plastic MCPs constitute the most critical BPA source and potential exposure pathways that require further investigation. Active collaboration among risk assessors, government, policy-makers, and researchers is needed to explore the impacts of BPA in the long term and introduce restrictions to BPA-based MCPs. Integr Environ Assess Manag 2023;19:45-62. © 2022 SETAC.

Development of Free-Standing Titanium Dioxide Hollow Nanofibers Photocatalyst with Enhanced Recyclability

Titanium dioxide hollow nanofibers (THN) are excellent photocatalysts for the photodegradation of Bisphenol A (BPA) due to their extensive surface area and good optical properties. A template synthesis technique is typically employed to produce titanium dioxide hollow nanofibers. This process, however, involves a calcination procedure at high temperatures that yields powder-form photocatalysts that require post-recovery treatment before recycling. Meanwhile, the immobilization of photocatalysts on/into a membrane has been reported to reduce the active surface area. Novel free-standing TiO₂ hollow nanofibers were developed to overcome those shortcomings. The free-standing photocatalyst containing 0.75 g of THN (FS-THN-75) exhibited good adherence and connectivity between the nanofibers. The recyclability of FS-THN-75 outperformed the THN calcined at 600 °C (THN-600), which retained 80% of its original weight while maintaining excellent degradation performance. This study recommends the potential application of free-standing TiO₂ hollow nanofibers as high potential novel photocatalysts for the treatment of BPA in wastewater.

Application of Microgel as a Sorbent for Bisphenol Analysis in Liquid Food Samples

Bisphenols are well-known endocrine disruptors that can easily migrate from plastic and can containers to food. Due to the complicated matrix and ultra-low concentrations of bisphenols in food, samples require extensive preparation before instrumental analysis. In this paper, an environmental sensitive microgel was employed as a sorbent for the preconcentration of four bisphenols, bisphenol A (BPA), bisphenol B (BPB), bisphenol E (BPE) and bisphenol F (BPF), from liquid food samples. Liquid chromatography with fluorescence detection (LC-FLD) was used for the quantification of bisphenols. By applying microgel solid-phase extraction procedure, the limits of detections achieved in liquid food samples can be lowered to 0.9 µg·L−1 for BPF and BPA, 2.3 µg·L−1 for BPE and 2.9 µg·L−1 for BPB. Only 5 mg of microgel was sufficient to achieve good recoveries (70.5–109%) with precision (RSD 0.21–5.01%, n = 3) for different analyzed liquid food samples spiked at concentration levels of 50 µg·L−1. In five out of twelve of the analyzed samples (pineapple, mandarin, peach, mushroom and pickles), they were contaminated with BPA, and the determined concentration was in the range of 6.2–22 µg·L−1; however, these results are below the specific migration limit (SML) set for BPA (50 µg·kg−1).

Zinc deficient diet increases the toxicity of bisphenol A in rat testis

Zinc (Zn) plays an important role in maintaining the process of spermatogenesis and reproductive health. Bisphenol A (BPA), an endocrine disrupting chemical is known to be a reproductive toxicant in different animal models. The present study was designed to study the effect of two of the utmost determinative factors (Zn deficient condition and influence of toxicant BPA) on germ cell growth and overall male reproductive health in the testis, epididymis, and sperm using (a) biochemical, (b) antioxidant, (c) cellular damage, (d) apoptosis, and (e) protein expression measurements. Rats were divided into Control (normal feed and water), BPA (100 mg/kg/d), zinc deficient diet (ZDD; fed with ZDD), and BPA + ZDD for 8 weeks. Body and organ weights, sperm motility and counts, and sperm head morphology were evaluated. The histology of testes, epididymides, and prostate was investigated. Testicular deoxyribonucleic acid (DNA) damage was evaluated by Halo and Comet assay, apoptosis of sperm and testes were quantified by TUNEL assay. Serum protein electrophoretic patterns and testicular protein expressions such as Nrf-2, catalase, PCNA, and Keap1 were analyzed by Western blot analysis. The results showed that BPA significantly increased the testicular, epididymal, and prostrate toxicity in dietary Zn deficient condition due to testicular hypozincemia, hypogonadism, increased cellular and DNA damage, apoptosis, as well as perturbations in protein expression.

Oxidative stress and immune disturbance after long-term exposure to bisphenol A in juvenile common carp (Cyprinus carpio)

Bisphenol A (BPA) is a well-known endocrine disrupting chemical (EDC), ubiquitous in the aquatic environment, which poses an ecotoxicological risk to the health of aquatic organisms. However, the immunotoxic effects of its long-term exposure on fish have received limited attention. We examined a number of typical immune-related parameters and oxidative stress indices in the liver and blood serum of the red common carp (Cyprinus carpio), following a 30-day exposure to five different concentrations of BPA (0.1, 1, 10, 100, and 1000μg/L). A significant increase in the hepato somatic index was observed in fish upon exposure to 1000µg/L BPA, which correlated strongly with the accumulated BPA concentrations in fish bile. Induced oxidative stress was also apparent in the exposed fish liver, based on the enhanced levels of lipid peroxidation and inhibited activities of catalase, superoxide dismutase, and glutathione peroxidase. Serum lysozyme and C-reaction protein levels increased at low concentrations of exposure; however, they were significantly suppressed upon exposure to high concentrations. A significant increase was observed in the levels of immunoglobulin M, complement component 3, and alkaline phosphatase, in both fish liver and serum at low doses of 0.1 and 1μg/L. This suggests that long-term exposure to environmentally relevant concentrations of BPA (even as low as 0.1μg/L) could significantly disturb the immune response of fish. Moreover, RXRα expression in the liver was significantly altered upon BPA exposure and the trend underlying this change correlated closely with those of the most immune-related parameters, implying the involvement of the PPARγ/RXRα signaling pathway in regulating the immune response of fish upon long-term BPA exposure. In short, our results demonstrate the susceptibility of fish immune system to long-term BPA exposure. Therefore, the immunotoxicity of EDCs in aquatic organisms should not have been underestimated.

The in vitro immune modulatory effect of bisphenol A on fish macrophages via estrogen receptor α and nuclear factor-κB signaling

Bisphenol A (BPA) is a well-known environmental endocrine-disrupting chemical. Employing primary macrophages from head kidney of red common carp (Cyprinus carpio), the present study aimed to evaluate the immune modulatory effect of BPA and to explore its potential action mechanism associated with estrogen receptor (ER) and nuclear factor-κB (NF-κB) pathways. A dynamic response process was observed in macrophages upon various concentrations of BPA exposure, which significantly enhanced the antibacterial activity of macrophages at 0.1, 1, or 10 μg/L, but instead induced the apoptosis at 100, 1000, and 10,000 μg/L. A potential pro-inflammatory effect of BPA exposure was suggested, judging from the increased production of nitrite oxide and reactive oxygen species (ROS), the induction of interleukin-1β mRNA and protein, as well as NF-κB and other NF-κB-associated immune gene expression. Following BPA coexposure with the ER or NF-κB antagonist, the induction of ROS, ERα, and NF-κB-associated immune gene expression was significantly inhibited, implying interaction between those two pathways. This study thus indicated that low doses of BPA exposure alone could significantly disturb the immune response of fish primary macrophages in vitro, and for the first time revealed the synergistic action of ERα and NF-κB transcription factors in the BPA effect.