Environmental fate of bisphenol A and its biological metabolites in river water and their xeno-estrogenic activity

Indian and global scenarios of Bisphenol A distribution and its new analogues: Prevalence & probability exceedance

We compare, the prevalence, fate, and sources of Bisphenol A both globally and in India. India has the highest concentration of BPA and Bisphenol S(BPS) in general, with vegetables, particularly corn, beans, strings, and raw or canned vegetables, being the largest contributors. Among all the matrices, bisphenols (BPs) are found in the highest concentration in food, followed by surface water, wastewater, and indoor dust. BPA, BPS, and BPF are the most commonly reported analogues in India, with BPA being the most dominant category used worldwide. The highest concentration of BPs is observed in Uttar Pradesh, Punjab and Haryana that are three major agricultural states of India however, there is still a research gap regarding the dietary exposure to BPs on an individual level. Environmentally detected BPA occurs in a range of below detection to 10636 ng. L-1, with significant geographic variations. Interestingly, the order of abundance in India was maximum for BPS, which is contrary to the global average, where BPA is observed as most abundant. BPS is found to be the most common BPs analogue in surface water worldwide, with limited removal efficiency by both naturally remediation and conventional treatment methods. Similar patterns were observed in the US-India and Japan-Korea regions in terms of their source-sink-prevalence-fate dynamics. The probability of exceeding safe concentrations of BPs is higher in India and Korea, suggesting that these countries are more vulnerable to high prevalence concentrations and the subsequent public health hazards.

The interfacial interaction between typical microplastics and Pb2+ and their combined toxicity to Chlorella pyrenoidosa

Microplastics (MPs), a new type of pollutant, have attracted much attention worldwide. MPs are often complexed with other pollutants such as heavy metals, resulting in combined toxicity to organisms in the environment. Studies on the combined toxicity of MPs and heavy metals have usually focused on the marine, while on the freshwater are lacking. In order to understand the combined toxic effects of MPs and heavy metals in the freshwater, five typical MPs (PVC, PE, PP, PS, PET) were selected to investigate the adsorption characteristics of MPs to Pb2+ before and after the MPs aging by ultraviolet (UV) irradiation through static adsorption tests. The results showed that UV aging enhanced adsorption of Pb2+ by MPs. It is noteworthy that MPs-PET had the highest adsorption capacity for Pb2+, and the interaction between MPs-PET and Pb2+ was the strongest. We specifically selected MPs-PET to study its combined toxicity with Pb2+ to Chlorella pyrenoidosa. In the combined toxicity test, MPs-PET and Pb2+ had significant toxic effects on Chlorella pyrenoidosa in the individual exposure, and the toxicity of individual Pb2+ exposure was greater than that of individual MPs-PET exposure. In the combined exposure, when MPs-PET and Pb2+ without adsorption (MPs-PET/Pb2+), MPs-PET and Pb2+ had a synergistic effect, which would produce strong physical and chemical stress on Chlorella pyrenoidosa simultaneously, and the toxic effect was the most significant. After the adsorption of MPs-PET and Pb2+ (MPs-PET@Pb2+), the concentration and activity of Pb2+ decreased due to the adsorption and fixation of MPs-PET, and the chemical stress on Chlorella pyrenoidosa was reduced, but the physical stress of MPs-PET still existed and posed a serious threat to the survival of Chlorella pyrenoidosa. This study has provided a theoretical basis for further assessment of the potential environmental risks of MPs in combination with other pollutants such as heavy metals.

Bisphenol A contamination in Hilsa shad and assessment of potential health hazard: A pioneering investigation in the national river Ganga, India

The anadromous Hilsa, often known as the "Queen of Fishes" (Tenualosa ilisha), is the most valuable fishery in the Ganga-Hooghly delta estuary. Although BPA exposure has been shown to be harmful to aquatic organisms, no research has looked at the effects of BPA on the commercially valuable Hilsa shad of river Ganga. To close this information vacuum, we examined BPA levels in Hilsa fish from the Ganga estuary. Liver, muscle, kidney, and gonads were all positive for BPA among the Hilsa fish of all ages. Liver BPA levels were highest in adult males (272.16 ± 0.38 ng/g-dw), and lowest in juveniles (5.46 ± 0.06 ng/g-dw). BPA concentrations in the Hilsa shad muscle were highest in reproductively mature females (196.23 ± 0.41 ng/g-dw). The study also discovered a correlation between fish development and BPA exposure, with higher levels of BPA being identified in adult Hilsa species. This is the first study to look at the impact of BPA pollution on aquatic ecosystems and fisheries, and it showed that Hilsa shad is contaminated with BPA and poses health hazards to human beings. The results, which demonstrate BPA contamination, are useful for protecting Hilsa in the river Ganga.

pH-dependent bisphenol A transformation and iodine disinfection byproduct generation by peracetic acid: Kinetic and mechanistic explorations

Peracetic acid (PAA) is regarded as an environmentally friendly oxidant because of its low formation of toxic byproducts. However, this study revealed the potential risk of generating disinfection byproducts (DBPs) when treating iodine-containing wastewater with PAA. The transformation efficiency of bisphenol A (BPA), a commonly detected phenolic contaminant and a surrogate for phenolic moieties in dissolved organic matter, by PAA increased rapidly in the presence of I-, which was primarily attributed to the formation of active iodine (HOI/I2) in the system. Kinetic model simulations demonstrated that the second-order rate constant between PAA and HOI was 54.0 M-1 s-1 at pH 7.0, which was lower than the generation rate of HOI via the reaction between PAA and I-. Therefore, HOI can combine with BPA to produce iodine disinfection byproducts (I-DBPs). The transformation of BPA and the generation of I-DBPs in the I-/PAA system were highly pH-dependent. Specifically, acidic conditions were more favorable for BPA degradation because of the higher reaction rates of BPA and HOI. More iodinated aromatic products were detected after 5 min of the reaction under acidic and neutral conditions, resulting in higher toxicity towards E. coli. After 12 h of the reaction, more adsorbable organic iodine (AOI) was generated at alkaline conditions because HOI was not able to efficiency transform to IO3-. The presence of H2O2 in the PAA solution played a role in the reaction with HOI, particularly under alkaline conditions. This study significantly advances the understanding of the role of I- in BPA oxidation by PAA and provides a warning to further evaluate the potential environmental risk during the treatment of iodine-bearing wastewater with PAA.

The association of bisphenol A and paraben exposure with sensorineural hearing loss in children

Bisphenol A (BPA) and parabens (PBs) are chemicals that are extensively used in personal care products (PCPs). In early childhood development, hearing is critical to speech and language development, communication, and learning. In vitro and in vivo, BPA/PBs exhibited neurotoxicity through elevated levels of oxidative stress. BPA also has the potential to be an ototoxicant. Therefore, this study aimed to determine the association of exposure to BPA/PBs with sensorineural hearing loss in children. A cross-sectional study based on hearing tests was conducted. This study enrolled 320 children aged 6-12 years from elementary school. Urinary BPA and PB concentrations were analyzed by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Logistic regression models were employed to determine the association of BPA/PB exposure with sensorineural hearing loss. Children with sensorineural hearing loss had higher BPA concentrations than normal-hearing children (0.22 ng/ml vs. 0.10 ng/ml, p = 0.05). After adjustment for covariates, the risk of hearing loss at middle frequencies reached 1.83-fold (95% CI: 1.12-2.99) when BPA concentrations increased by 1 log10. The risk of slight hearing loss reached 2.24-fold (95% CI: 1.05-4.78) when children had a tenfold increase in ethyl paraben (EP) concentration. This study clarifies the role of exposure to BPA/PBs in hearing loss in children. Future research needs to be expanded to include cohort designs and nationwide studies to identify causality.

Bisphenols in water: Occurrence, effects, and mitigation strategies

Bisphenols (bisphenol A (BPA), bisphenol S (BPS), bisphenol F (BPF) and bisphenol AF (BPAF)) are widely used as additives in numerous industries and therefore they are ubiquitously present throughout the world's natural environment including water. A review of the literature is presented on their sources, pathways of entry into the environment, and especially aquatic contexts, their toxicity to humans and other organisms and the technologies for removing them from water. The treatment technologies used are mostly adsorption, biodegradation, advanced oxidation, coagulation, and membrane separation processes. In the adsorption process, several adsorbents, especially carbon-based materials, have been tested. The biodegradation process has been deployed and it involves a variety of micro-organisms. Advanced oxidation processes (AOPs) such as UV/O₃-based, catalysis relevant AOPs, electrochemical AOPs and physical AOPs have been employed. Both the biodegradation process and AOPs generate by-products which may be toxic. These by-products need to be subsequently removed using other treatment processes. Effectiveness of the membrane process varies depending on the porosity, charge, hydrophobicity, and other properties of the membrane. The problems and limitations of each treatment technique are discussed and methods to overcome them are presented. Suggestions are articulated to use a combination of processes to improve the removal efficiencies.

Mn(III)-mediated bisphenol a degradation: Mechanisms and products

Bisphenol A (BPA) is a high production volume chemical with potential estrogenic effects susceptible to abiotic degradation by MnO₂. BPA transformation products and reaction mechanisms with MnO₂ have been investigated, but detailed process understanding of Mn(III)-mediated degradation has not been attained. Rapid consumption of BPA occurred in batch reaction vessels with 1 mM Mn(III) and 63.9 ± 0.7% of 1.76 ± 0.02 μmol BPA was degraded in 1 hour at circumneutral pH. BPA was consumed at 1.86 ± 0.09-fold higher rates in vessels with synthetic MnO₂ comprising approximately 13 mol% surface-associated Mn(III) versus surface-Mn(III)-free MnO₂, and 10-35% of BPA transformation could be attributed to Mn(III) during the initial 10-min reaction phase. High-resolution tandem mass spectrometry (HRMS/MS) analysis detected eight transformation intermediates in reactions with Mn(III), and quantum calculations proposed 14 BPA degradation products, nine of which had not been observed during MnO₂-mediated BPA degradation, suggesting mechanistic differences between Mn(III)- versus MnO₂-mediated BPA degradation. The findings demonstrate that both Mn(III) and Mn(IV) can effectively degrade BPA and indicate that surface-associated Mn(III) increases the reactivity of synthetic MnO₂, offering opportunities for engineering more reactive oxidized Mn species for BPA removal.

Novel cubical Ag(NP) decorated titanium dioxide supported bentonite thin film in the efficient removal of bisphenol A using visible light

The persistent endocrine-disrupting chemical bisphenol A is posing serious health concerns; hence, it is known to be an emerging and potential water contaminant. The present investigation aims to synthesize novel cubical Ag(NP) decorated titanium dioxide-supported bentonite (Ag/TiO₂@Clay) nanocomposite using a novel synthetic process. The nanocomposite materials were characterized by several analytical methods viz., transmission electron microscopy (TEM), X-ray diffraction (XRD) analyses, energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) and diffuse reflectance spectroscopy (DRS). Further, the photocatalytic removal of bisphenol A was conducted utilizing the thin film catalyst under the LED (light emitting diode; visible light) and UV-A (ultra violet-A) light sources. The parametric studies solution pH (6.0-12.0), pollutant concentrations (1.0-20.0 mg/L), and the interaction of several scavengers and co-existing ions are studied extensively to demonstrate the insights of the removal mechanism. The mineralization of bisphenol A and repeated use of the thin film catalyst showed the potential usage of photocatalysts in the devised large-scale operations. Similarly, the natural matrix treatment was performed to evaluate the suitability of the process for real implications.

Preparation of Magnetic Metal-Organic Frameworks@Molecularly Imprinted Nanoparticles for Specific Extraction and Enrichment of Bisphenol A in Food

Metal-organic frameworks (MOFs) with systematically tailored structures have been suggested as promising precursors to the preparation of diverse functional materials. Herein, a facile and versatile layer-by-layer strategy without any special surface modifications has been proposed for the preparation of magnetic metal-organic frameworks (MMOFs) supported molecularly imprinted polymer nanoparticles (MMOFs@MIP), which are based on a magnetically susceptible core conjugated with an imidazole-derived self-assembled layer and a silane-based imprinted shell. The obtained MMOFs@MIPs, which integrated the advantages of Fe₃O₄, MOFs, and MIPs, were characterized and exhibited good magnetic properties, a rapid mass transfer rate, and an excellent adsorption selectivity as well as capacity for the targeted molecular - bisphenol A (BPA). Moreover, the MMOFs@MIPs were employed as adsorbents in magnetic solid phase extraction (MSPE) to selectively bind and rapidly separate BPA from real samples with satisfactory recoveries ranging from 88.3% to 92.3%. More importantly, the desirable reusability of MMOFs@MIP was also evaluated, and the recoveries still maintained above 88.0% even after five re-use cycles. Furthermore, combined with high-performance liquid chromatography (HPLC) analysis, a novel MSPE-HPLC method was developed, enabling the highly selective and sensitive detection of BPA in a wide linear range of 0.5–5000 μg L⁻¹ with a low limit of detection (LOD) of 0.1 μg L⁻¹. This work contributes a promising method for constructing various functional nanoparticles @MOFs@MIP hybrid materials for applications in many different fields.

Removal of endocrine disrupters from the contaminated environment: public health concerns, treatment strategies and future perspectives - A review

Endocrine-disrupting compounds (EDCs) are emerging contaminants of concern (ECC) that disturb endocrine hormones and system functionality even at very low concentrations (i.e. μg/L or ng/L levels). Hence, EDCs are found in all components of the environment including surface and groundwater, wastewater, soil, outdoor and indoor air and in the contaminated foods from a variety of sources (run off from agricultural activities, sewage treatment plants, leakage from septic tanks etc.), and the effects are more severe as the majority of EDCs do not have standard regulations. The environmental mobility of EDCs is higher as conventional wastewater treatment does not degrade efficiently and the development of effective and sustainable removal technologies specifically designed for the removal of those emerging micropollutants is essential. Accordingly, EDCs cause various public health diseases such as reproductive abnormalities, obesity, various cancer types, cardiovascular risks, metabolic disorders, epigenetic alterations, autism, etc. This paper reviews the existing and emerging treatment technologies for the removal of phenolic based EDCs, such as natural estrogens (estrone (E1), 17β-estradiol (E2), estriol (E3)), synthetic estrogen 17α-ethinylestradiol (EE2) and phenolic xenoestrogens (4-nonyl phenols (4-NP) and bisphenol-A (BPA)) from the contaminated environment. These includes advanced oxidation processes (AOP), adsorption processes, membrane based filtration, bioremediation, phytoremediation and other integrated approaches. The sustainability of EDCs removal can be assured through the use of combined processes (i.e. low-cost - biological and adsorption methods with efficient and costly - AOPs) techniques through system integration to achieve better removal efficiency than using a single treatment technique. Besides, the public health concerns and future research perspectives of EDCs are also highlighted.

Nanostructured Hypercrosslinked Porous Organic Polymers: Morphological Evolution and Rapid Separation of Polar Organic Micropollutants

Nanostructured hypercrosslinked porous organic polymers have triggered immense research interest for a broad spectrum of applications ranging from catalysis to molecular separation. However, it still remains a challenge to tune their nanoscale morphology. Herein, we demonstrated a remarkable variation of morphologies of triptycene-based hypercrosslinked microporous polymers starting from irregular aggregates (FCTP) to rigid spheres (SCTP) to two-dimensional nanosheets (SKTP) from three distinct polymerization methodologies, Friedel-Crafts knitting using an external crosslinker, Scholl reaction, and solvent knitting, respectively. Further, the dramatic role of reaction temperatures, catalysts, and solvents resulting in well-defined morphologies was elucidated. Mechanistic investigations coupled with microscopic and computational studies revealed the evolution of 2D nanosheets of a highly porous solvent-knitted polymer (SKTP, 2385 m² g^-1), resulting from the sequential hierarchical self-assembly of nanospheres and nanoribbons. A structure-activity correlation of hypercrosslinked polymers and their sulfonated counterparts for the removal of toxic polar organic micropollutants from water was delineated based on the chemical functionalities, specific surface area, pore size distribution, dispersity, and nanoscale morphology. Furthermore, a sulfonated 2D sheet-like solvent-knitted polymer (SKTPS) exhibited rapid adsorption kinetics (within 30 s) for a large array of polar organic micropollutants, including plastic components, steroids, antibiotic drugs, herbicides, and pesticides with remarkable uptake capacity and excellent recyclability. The current study provides the impetus for designing morphology-controlled functionalized porous polymers for task-specific applications.

Removal of contaminants of emerging concern from multicomponent systems using carbon dioxide activated biochar from lignocellulosic feedstocks

Adsorption of six contaminants of emerging concern (CECs) - caffeine, chloramphenicol, carbamazepine, bisphenol A, diclofenac, and triclosan - from a multicomponent solution was studied using activated biochars obtained from three lignocellulosic feedstocks: wheat straw, softwood, and peach stones. Structural parameters related to the porosity and ash content of activated biochar and the hydrophobic properties of the CECs were found to influence the adsorption efficiency. For straw and softwood biochar, activation resulted in a more developed mesoporosity, whereas activation of peach stone biochar increased only the microporosity. The most hydrophilic CECs studied, caffeine and chloramphenicol, displayed the highest adsorption (22.8 and 11.3 mg g^-1) onto activated wheat straw biochar which had the highest ash content of the studied adsorbents (20 wt%). Adsorption of bisphenol A and triclosan, both relatively hydrophobic substances, was highest (31.6 and 30.2 mg g^-1) onto activated biochar from softwood, which displayed a well-developed mesoporosity and low ash content.

Environmental Estrogens and Their Biological Effects through GPER Mediated Signal Pathways

Many environmental chemicals have been found to exert estrogenic effects in cells and experimental animals by activating nuclear receptors such as estrogen receptors and estrogen-related receptors. These compounds include bisphenols, pesticides, polybrominated diphenyl ethers (PBDEs), organophosphate flame retardants, phthalates and metalloestrogens. G protein-coupled estrogen receptor (GPER) exists widely in numerous cells/tissues of human and other vertebrates. A number of studies have demonstrated that GPER plays a vital role in mediating the estrogenic effects of environmental pollutants. Even at very low concentrations, these chemicals may activate GPER pathways, thus affect many aspects of cellular functions including proliferation, metastasis and apoptosis, resulting in cancer progression, cardiovascular disorders, and reproductive dysfunction. This review summarized the environmental occurrence and human exposure levels of these pollutants, and integrated current experimental evidence toward revealing the underlying mechanisms of pollutant-induced cellular dysfunction via GPER. The GPER mediated rapid non-genomic actions play an important role in the process leading to the adverse effects observed in experimental animals and even in human beings.

Sediments in the mangrove areas contribute to the removal of endocrine disrupting chemicals in coastal sediments of Macau SAR, China, and harbour microbial communities capable of degrading E2, EE2, BPA and BPS

The occurrence of endocrine disrupting chemicals (EDCs) is a major issue for marine and coastal environments in the proximity of urban areas. The occurrence of EDCs in the Pearl River Delta region is well documented but specific data related to Macao is unavailable. The levels of bisphenol-A (BPA), estrone (E1), 17α-estradiol (αE2), 17β-estradiol (E2), estriol (E3), and 17α-ethynylestradiol (EE2) were measured in sediment samples collected along the coastline of Macao. BPA was found in all 45 collected samples with lower BPA concentrations associated to the presence of mangrove trees. Biodegradation assays were performed to evaluate the capacity of the microbial communities of the surveyed ecosystems to degrade BPA and its analogue BPS. Using sediments collected at a WWTP discharge point as inoculum, at a concentration of 2 mg l^-1 complete removal of BPA was observed within 6 days, whereas for the same concentration BPS removal was of 95% after 10 days, which is particularly interesting since this compound is considered recalcitrant to biodegradation and likely to accumulate in the environment. Supplementation with BPA improved the degradation of bisphenol-S (BPS). Aiming at the isolation of EDCs-degrading bacteria, enrichments were established with sediments supplied with BPA, BPS, E2 and EE2, which led to the isolation of a bacterial strain, identified as Rhodoccoccus sp. ED55, able to degrade the four compounds at different extents. The isolated strain represents a valuable candidate for bioremediation of contaminated soils and waters.

2,2-Bis(4-Hydroxyphenyl)-1-Propanol-A Persistent Product of Bisphenol A Bio-Oxidation in Fortified Environmental Water, as Identified by HPLC/UV/ESI-MS

Biodegradation of bisphenol A in the environmental waters (lake, river, and sea) has been studied on the base of fortification of the samples taken and the biodegradation products have been analyzed using HPLC/UV/ESI-MS. Analysis of the characteristic fragmentation patterns of [M-H]^- ions permitted unambiguous identification of the biodegradation products as 2,2-bis(4-hydroxyphenyl)-1-propanol or as p-hydroxyacetophenone, depending on the type of surface water source. The formation of 2,2-bis(4-hydroxyphenyl)-1-propanol was much more common than that of p-hydroxyacetophenone. Moreover, 2,2-Bis(4-hydroxyphenyl)-1-propanol has not been further biodegraded, in contrast to the p-hydroxyacetophenone, which was further mineralized. It has been proved, for the first time, that 2,2-bis(4-hydroxyphenyl)-1-propanol can be regarded as persistent product of bisphenol A biodegradation in the fortified environmental waters.

Bisphenol A and its analogues in sedimentary microplastics of Hong Kong

The occurrence and spatial distribution of bisphenol A (BPA) and analogues bisphenol B (BPB), bisphenol F (BPF) and bisphenol S (BPS) were investigated in microplastic on 11 beaches in Hong Kong. At 10 sites, BPA was the only detected chemical with concentrations ranged from 82.4-989 ng g^-1 microplastic. BPA, BPB and BPS co-occurred at only one site, where it is located close proximity to the outfall of a sewage treatment plant. There was no significant spatial difference of BPA concentrations in microplastic when all the sites were considered, indicating that some remote and presumably cleaner beaches have been contaminated. PE, PP and PS (represented >90% of total polymers) were the most dominated polymers, but there was no correlation between polymer types and BPA concentrations. No evidence was found that the BPA and its analogues accumulate on microplastic since the concentrations were comparable to those found in the sediment.

Urinary bisphenol A concentrations and adiposity measures at age 7 years in a prospective birth cohort

Bisphenol A (BPA) exposure during early life may increase risk of childhood obesity, however, prospective evidence of birth cohort is limited and inconclusive. We aimed to explore the associations of maternal and childhood BPA exposure with child adiposity measures, including body mass index, waist circumference and skinfold thickness and waist to height ratio of children at 7 years. 430 mother-child pairs were examined from a population-based prospective cohort in a rural area of East China. BPA concentrations of spot urine samples were quantified in mothers and their children aged 3 and 7 years. Maternal urinary BPA concentration was significantly positively associated with waist circumference in children aged 7 years (β = 0.508 cm, 95% CI: 0.067, 0.950). These significant associations were not modified by child sex, but they were only observed among girls in sex-stratified analyses. Risk of central obesity related to prenatal BPA exposure was significantly higher in the second and the third tertile than those in the first tertile (odds ratio, OR = 2.510, 95% CI = 1.146, 5.499; OR = 2.584, 95% CI = 1.186, 5.631, respectively; p for trend = 0.022). The present findings suggested that prenatal exposure to BPA may enhance waist circumference of children and thereby increase risk of central obesity in school-age girls.

Innovative depollution treatment using multi-valent iron species: from fundamental study to application in municipal wastewater

In this work, a new combination of oxidation treatments for the degradation of bisphenol A (BPA) is investigated. This innovative wastewater (WW) treatment includes the use of ferrate (FeO₄^2-) and its decomposition byproducts under dark and UVA irradiation. The oxidation by ferrate leads to a fast but incomplete degradation of BPA with a degradation extent of 45% after 60 min under adopted experimental conditions. However, the ferrate decomposition byproducts which are constituted by solid iron species can be used to further improve the pollutant degradation efficiency. Indeed, ferrate-mediated heterogeneous photo-Fenton process is employed for the first time to enhance the degradation of BPA. With respect to the application for wastewater treatment, UVA irradiation (which is part of solar light), non-toxic and natural origin compounds such as ascorbic acid (AA) and ethylenediamine-N,N'-disuccinic acid (EDDS), are used to design a sustainable process. Under optimized conditions, the degradation extent of BPA using this newly designed treatment reaches almost 100% with AA and 70% with EDDS. In order to assess the feasibility of this treatment, the ferrate-mediated photo-Fenton process is applied to treat municipal wastewater. The obtained results in WW are highly encouraging since a maximum BPA degradation extent of 63% and 60% is observed after 300 min by using AA and EDDS, respectively.

Cloning and molecular characterization of estrogen-related receptor (ERR) and vitellogenin genes in the brackish water flea Diaphanosoma celebensis exposed to bisphenol A and its structural analogues

Although it has previously been shown that bisphenol (BP) analogues may interfere with the normal hormonal regulation by acting as endocrine disrupting chemicals (EDCs), little information is available on effects of BP analogues in invertebrates, particularly on cladocerans. In the present study, we identified estrogen-related receptors (EER), vitellogenin (VTG), and VTG receptor (VtgR) from the brackish water flea Diaphanosoma celebensis, and examined the effects of BPA and the substitutes, BPF and BPS, in different sublethal concentrations. Gene expression varied with time well matched with brooding, suggesting that DcEER, DcVTG, and DcVtgR play a role in reproduction in D. celebensis. qRT-PCR analysis showed that BPA and its substitutes differently modulated mRNA expressions of DcEER, DcVTG, and DcVtgR, indicating that these compounds adversely affect the normal reproduction-related pathway. This study facilitates better understanding of the molecular mode of action of BP analogues on the reproductive system of D. celebensis.

Highly ordered molecularly imprinted mesoporous silica for selective removal of bisphenol A from wastewater

Selective removal of bisphenol A from wastewater is quite challenging primarily because of its low concentration and matrix complexity. To this end, according to the molecular structure of bisphenol A, we designed a functional monomer for the preparation of molecularly imprinted mesoporous silica using click chemistry reaction. The resultant bisphenol A imprinted mesoporous silica was characterized by transmission electron microscopy, small angle X-ray diffraction, and N₂ adsorption-desorption experiments. The results indicated that the bisphenol A imprinted mesoporous silica possessed a highly ordered periodic hexagonal mesostructure with the Brunauer-Emmett-Teller surface area of 944.28 m² /g. The bisphenol A imprinted mesoporous silica showed fast adsorption kinetics and the saturated adsorption capacity reached up to 88.6 mg/g at pH 6.5, and with relative selectivity factors ranged from 1.06 to 3.20. The adsorption efficiency of the bisphenol A imprinted mesoporous silica was above 97.96% after five extraction/elution cycles. The bisphenol A imprinted mesoporous silica was further applied to the selective removal of bisphenol A from real wastewater samples and showed great promise in practical applications.

Insights into removal mechanisms of bisphenol A and its analogues in municipal wastewater treatment plants

The occurrence and removal mechanisms of bisphenol A (BPA) and its analogues in municipal WWTPs were critically reviewed in this article. BPA appeared to be the dominant bisphenol, and the removal efficiency of bisphenols was in the order of bisphenol AP>bisphenol P>bisphenol F>bisphenol Z>bisphenol C>bisphenol S>bisphenol B>BPA>bisphenol E>bisphenol AF. It was also found that BPA removal showed linear relationships to those of its analogues, which have been proven by BPA vs BPS or BPF. BPA removal performances in different treatment processes ranked from low to high are primary treatment, lagoon process, biological aerated filter, and activated sludge. Lab-scale studies showed that >50% BPA can be removed by sewage sludge estimated with the BPA solid water distribution coefficients, which showed that sludge adsorption played an important role on BPA removal. The theoretically predicted removal of BPA in municipal WWTP showed that it is readily biodegradable, which deviate from its on-site investigations. Existence of BPA conjugates in raw municipal wastewater as well as newly produced BPA degraded or migrated from microplastic materials are possible two main reasons.

Levels of NP and BPA in the Pearl River Estuary, China: Fluctuations with Country Policy Changes over the Past 40 Years

Sediment cores were collected from four outlets in the Pearl River Estuary (Guangdong Province, China) and dated using the ²¹⁰Pb method to investigate the pollution history of the area due to its relatively stable sedimentation status and hydrographic conditions in recent decades. The ages of the sediment cores were dated over 40 years (1968–2015). The concentrations at the four outlets ranged from 2.21 to 48.52 ng g⁻¹ dw for nonylphenol and were non-detectable for 23.64 ng g⁻¹ dw for bisphenol A (BPA), which exhibited a decreasing trend from north to south as well as seaward. The fluxes (2.84 to 112.91 ng cm⁻² yr⁻¹ and non-detectable to 59.33 ng cm⁻² yr⁻¹ for nonylphenol and bisphenol A, respectively) stabilized in the 1980s to 1990s due to the construction of sewage treatment systems. The fluxes increased again in the 21st century, which reached a peak ca. 2010 but declined in recent years due to the establishment of regulations and the decreasing number of industrial enterprises. Fluctuations in the pollution composition coincided with industrial development and governmental policies.

Acute toxicity of bisphenol A and its structural analogues and transcriptional modulation of the ecdysone-mediated pathway in the brackish water flea Diaphanosoma celebensis

Bisphenol A (BPA) is a representative endocrine disrupting chemical (EDC) that has estrogenic effects in aquatic animals. In recent years, due to the continuing usage of BPA, its analogues have been developed as alternative substances to replace its use. The molting process is a pivotal point in the development and reproduction of crustaceans. However, studies of the effects of EDCs on molting in crustaceans at the molecular level are scarce. In the present study, we examined the acute toxicity of BPA and its analogues bisphenol F (BPF) and S (BPS) to the brackish water flea Diaphanosoma celebensis. We further identified four ecdysteroid pathway - related genes (cyp314a1, EcRA, EcRB, and USP) in D. celebensis, and investigated the transcriptional modulation of these genes during molting and after exposure to BPA and its analogues for 48 h. Sequencing and phylogenetic analyses revealed that these four genes are highly conserved among arthropods and may be involved in development and reproduction in the adult stage. The mRNA expression patterns of cyp314a1, EcRA and USP were matched with the molting cycle, suggesting that these genes play a role in the molting process in the adult stage in cladocerans. Following relative real-time polymerase chain reaction (RT-PCR) analyses, BPA and its analogues were found to modulate the expression of each of these four genes differently, indicating that these compounds can disrupt the normal endocrine system function of D. celebensis. This study improves our understanding of the molecular mode of action of BPA and its analogues in D. celebensis.

Associations between prenatal exposure to bisphenol a and neonatal outcomes in a Taiwanese cohort study: Mediated through oxidative stress?

This study determined whether maternal bisphenol A (BPA) exposure influences birth outcomes through oxidative stress and estimated the daily intake of BPA through breast milk for infants. One hundred and eighty-six pregnant women without pregnancy complications were enrolled and maternal urine was collected in the third trimester. Postnatal breast milk was collected in the first and third months after delivery. Concentrations of BPA were determined through ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. Generalized additive model-penalized regression splines and a multivariable regression model were employed to determine the effects of BPA exposure and oxidative stress levels on birth outcomes. A causal mediation analysis was conducted to clarify the mediation effects of oxidative stress due to maternal BPA exposure on birth outcomes. The daily intake of BPA in breast milk was calculated using probabilistic risk assessment methods. The geometric means (geometric standard deviation) of BPA levels for maternal urine and first- and third-month breast milk were 2.19 (2.88) μg/g creatinine., 1.35 (3.53) ng/g, and 3.17 (2.97) ng/g, respectively. No significant mediation existed among maternal BPA exposure, oxidative stress level, and neonatal head circumference. Three percent of 1-monthold babies and 1% of 3-month-old babies exceeded the BPA tolerable daily intake of 4 μg/kg-bw/day proposed by the European Food Safety Authority. This study revealed the BPA exposure profile for pregnant women and infants in northern Taiwan. The marginally significant correlation between maternal BPA exposure and neonatal head circumference should be considered.

Supramolecular solvent-based microextraction of emerging bisphenol A replacements (colour developers) in indoor dust from public environments

Bisphenol A (BPA) is present in a wide variety of materials and it is a well-known endocrine disruptor that is widespread in indoor and outdoor environments. For this reason, industry has introduced a variety of replacements, such as Bisphenol S (BPS) or Bisphenol F (BPF), and other less known structural analogs, such as BPS-MAE, D-8 or TGSA. These emerging potential contaminants have been identified in thermal paper products, according to recent studies, but their potential toxic effects and their migration into the environment remain unclear. In this study, we report for the first time the presence of emerging BPA replacements in indoor dust from public environments (shops, restaurants, etc.). For this purpose, we optimized a novel supramolecular solvent (SUPRAS)-based microextraction method. SUPRAS are multi-target solvents made up of self-assembled amphiphiles. They offer multiple extraction interactions (dispersion, polar, hydrophobic, etc.) and they constitute excellent candidates to develop generic and fast sample treatment procedures at low cost. By this method, emerging BPA replacements (BPS-MAE, D-8 and TGSA) were detected in dust at median concentrations in the range 6-22 ng g^-1 (around ten times lower than BPS) with detection frequencies in the range 50-90%. These results constitute a first insight into the migration of emerging BPA replacements into the environment via indoor dust, which is a common route of human exposure to contaminants.

Cometabolic degradation of bisphenol A by pure culture of Ralstonia eutropha and metabolic pathway analysis

Bisphenol A (BPA) is a toxic compound emitting to the environment mainly by polycarbonate production facilities. In this research, BPA with the initial concentrations in the range of 1-40 mg l^-1 was degraded by Ralstonia eutropha. The bacteria were unable to use BPA as the sole carbon source. Therefore, resting and growing cells of phenol-adapted R. eutropha were used for cometabolic biodegradation of BPA with phenol at the concentration of 100 mg l^-1. The optimum initial concentrations of BPA were 20 mg l^-1 in both approaches of cometabolism. By using resting cells, BPA removal efficiency (RE) reached to 57%, however, RE decreased to 37% by growing cells in the presence of phenol. BPA-degrading activity was inhibited at BPA concentrations >20 mg l^-1. Liquid chromatography-mass spectrometry technique was used to identify some metabolic intermediates generated during BPA degradation process as 1,2-bis(4-hydroxyphenyl)-2-propanol, 4-(2-propanol)-phenol, 4-hydroxyacetophenone, 4-isopropenylphenol, and 4-hydroxybenzoic acid. Finally, metabolic pathways for BPA degradation were proposed in this study.

Occurrence and fate of bisphenol A transformation products, bisphenol A monomethyl ether and bisphenol A dimethyl ether, in wastewater treatment plants and surface water

Due to the wide use, bisphenol A (BPA) has been detected frequently in the aquatic environment. However, the information on the distribution of BPA transformation products is limited. In this study, we investigated two BPA transformation products, namely bisphenol A monomethyl ether (BPA-MME) and bisphenol A dimethyl ether (BPA-DME). This study revealed that both transformation products were widely detected in the wastewater treatment plants (WWTPs) as well as in surface water of Jiulong River and its estuary with higher detected concentrations and detection frequencies for BPA-DME. Temporal variations were observed in a WWTP based on a five-year sampling campaign. Mass load of BPA and its transformation products was evaluated and results indicated the generation of BPA-MME and BPA-DME during the wastewater treatment processes, which contributed for 1.95% BPA removal. BPA and its transformation products were also widely detected in the surface water of Jiulong River and its estuary. Results indicated their additional generation in the surface water, since BPA-MME and BPA-DME in the surface river water were with similar level or even higher than effluent in WWTPs.

Survey of Octylphenol, Nonylphenol, and Bisphenol A in Infant Milk Powders by Solid-Phase Extraction Combined GC/MS Method

A detection method for 3 kinds of phenolic compounds of endocrine disruptors (4-nonylphenol, 4-octylphenol, and bisphenol A) in infant milk powders by solid-phase extraction combined GC-MS was established. This method can effectively remove interference materials from infant milk powder products. The limit of detection and the limit of quantitation of the 3 kinds of compounds were 0.8 μg/kg and 2.5 μg/kg, respectively, with the relative standard deviations of 4.3–12.1%. The recovery rates of 4-nonylphenol, 4-octylphenol, and bisphenol A were of 68.5–89.2%, 64.8–87.0%, and 97.8–110.0%, respectively. Concentrations of the bisphenol A were from 0.8 to 14 μg/kg in 35 samples of the total 60 samples. And the other two compounds of 4-nonylphenol and 4-octylphenol were not found in all the 60 samples tested. The established method is simple, rapid, accurate, and highly sensitive, and the pollution of endocrine disruptors in some infant milk powders products was detectable in trace amounts.

Degradation of bisphenol A through transition metals activating persulfate process

In this study, the process of transition metals (Fe²⁺, Fe⁰, Ni₂O₃) activating persulfate was attempted to degrade aqueous bisphonel A (BPA). Compared with thermal activation mode, significant degradation can be achieved at normal atmospheric temperature in transition metal activation mode. BPA removal in the transition metal-PS system can be divided into rapid phase (0-5 min) and slow phase (5-60 min). In rapid phase, 87.71% and 90.60% removal efficiencies were obtained in the Fe²⁺-PS and Ni₂O₃-PS systems, and the contaminant was almost completely oxidized after 60 min. There are many similarities between the Fe²⁺-PS and Fe⁰-PS systems, in particular the optimal removal efficiencies were achieved at n₀(Fe²⁺):n₀(PS) = 1:2 and n₀(Fe⁰):n₀(PS) = 1:2 rather than with maximum metal dosage. The Ni₂O₃ dosage had positive correlation with BPA removal rate while the degradation efficiency of the Fe²⁺-PS system could be promoted by keeping n₀(sodium citrate):n₀(Fe²⁺) below 1:1. Intermediate products of the Fe²⁺-PS system were analyzed by LC-MS and were predominantly phenol, p-hydroxyacetophenone, benzoquinone and propanedioic acid, therefore a possible oxidation degradation pathway was speculated.

Stop eating plastic, molecular signaling of bisphenol A in breast cancer

Breast cancer is the second most common fatal cancer in women. Developing a breast cancer is a multi-factorial and hormonal-dependent process, which may be triggered by many risk factors. An endocrine disrupting substance known as bisphenol A (BPA), that is used greatly in the manufacture of plastic products, was suggested as a possible risk factor for developing breast cancer. BPA has a strong binding affinity to non-classical membrane estrogen receptors like estrogen-related and G protein-coupled (GPER) receptors. Based on animal and in vitro studies, results showed a link between BPA exposure and increased incidence of breast cancer. BPA has the ability to alter multiple molecular pathways in cells namely, G protein-coupled receptor (GPER) pathway, estrogen-related receptor gamma (ERRγ) pathway, HOXB9 (homeobox-containing gene) pathway, bone morphogenetic protein 2 (BMP2) and (BMP4), immunoregulatory cytokine disturbance in the mammary gland, EGFR-STAT3 pathway, FOXA1 in ER-breast cancer cells, enhancer of zeste homolog 2 (EZH2), and epigenetic changes. Thus, the aforementioned alterations cause undesired gene stimulation or repression that increase risk of developing breast cancer. So, restricting exposure to BPA should be considered to aid in lowering the risk of developing breast cancer.

Comparative analysis of BPA and HQ toxic impacts on human erythrocytes, protective effect mechanism of tannins (Rhus typhina)

Several studies reported that bisphenol A (BPA) and its metabolite hydroquinone (HQ) have adverse effects on human and animal health. In this work, a comparative study of influence of the BPA and HQ, environment pollutants, on human erythrocytes was carried out. It was shown that BPA and HQ to varying extents caused oxidative damage in human erythrocytes: hemolysis, decreased GSH level, and methemoglobin formation. It was demonstrated that hydrolysable tannins 3,6-bis-O-di-O-galloyl-1,2,4-tri-O-galloyl-β-D-glucose (C₅₅H₄₀O₃₄) and 1,2,3,4,6-penta-O-galloyl-β-D-glucose (C₄₁H₃₂O₂₆) (PGG) isolated from the Rhus typhina L. leaves in the range of 1-50 μM concentrations inhibited hemolysis and methemoglobin formation and also increased intracellular reduced glutathione in erythrocytes treated with BPA or HQ. It was revealed by electron paramagnetic resonance (EPR) using 5-doxyl-stearic acid (5-DS) that C₅₅H₄₀O₃₄ and C₄₁H₃₂O₂₆ increased the rigidity of erythrocyte membranes at the depth of 5th carbon atom of the fatty acid hydrocarbon chain. Taken together, these results allow to conclude that tannins from the Rhus typhina L. leaves protect erythrocytes from oxidative stress caused by BPA or HQ both due to their antioxidant activity as well as their interaction with the erythrocyte membrane components.

Efficient activation of persulfate by Fe3O4@β-cyclodextrin nanocomposite for removal of bisphenol A

Experimental studies were conducted to investigate the degradation of bisphenol A (BPA) by using persulfate (PS) as the oxidant and Fe₃O₄@β-cyclodextrin (β-CD) nanocomposite as a heterogeneous activator. The catalytic activity was evaluated in consideration of the effect of various parameters, such as pH value, PS concentration and Fe₃O₄@β-CD load. The results showed that 100% removal of BPA was gained at pH 3.0 with 5 mM PS, 1.0 g L⁻¹ Fe₃O₄@β-CD, and 0.1 mM BPA in 120 min. Further, the catalytic activity of Fe₃O₄@β-CD nanocomposite was observed as much higher when compared with Fe₃O₄ nanoparticles alone. The sulfate and hydroxyl radicals referred to in the Fe₃O₄@β-CD/PS system were determined as the reactive species responsible for the degradation of BPA by radical quenching and electron spin resonance (ESR) tests. In addition, the catalyst also possessed with accepted reusability and stability. On the basis of the results of the effect of chloride ions (Cl⁻), β-CD was found to play a crucial role in reducing interference from Cl⁻ ions, and lead to achieve higher removal efficiency for BPA in Fe₃O₄@β-CD/PS system. A possible mechanistic process of BPA degradation was proposed according to the identified intermediates by gas chromatography-mass spectroscopy (GC-MS).

Persulfate (PS), the most commonly used activator for in situ chemical oxidation (ISCO), could couple with Fe₃O₄@β-CD for effectively degrading BPA.

Glucuronide and Sulfate Conjugates of Bisphenol A: Chemical Synthesis and Correlation Between Their Urinary Levels and Plasma Bisphenol A Content in Voluntary Human Donors

Bisphenol A (BPA) glucuronide and sulfate conjugates are major products of Phase II metabolism of BPA in humans. In the past, their determination in body fluids usually involves tedious enzymatic hydrolysis and multiresidual analysis. The recent availability of authentic standards of these conjugates enables our better understand of the human metabolism of BPA and the distribution of their metabolites in body fluids. In this work, we report the chemical synthesis and purification of BPA mono- and di-glucuronide and BPA mono- and di-sulfate. Their levels, as well as that of BPA, in 140 paired human plasma and urine samples collected randomly from voluntary donors in Hong Kong SAR, China, were determined by solid-phase extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS). BPA was found in more than 135 human plasma and urine samples. Its Phase II metabolites, ranging from N.D. to 36.7 µg g^-1-creatinine, also were detected in 139 of the 140 urine samples. Good correlation (r = 0.911) between molar concentration of BPA in the plasma and that of "total urinary BPA" (i.e., ln [(BPA + ∑ BPA phase II conjugate)_{molar concentration}]) was observed. Direct quantification of Phase II metabolites of BPA in human urine can be a useful assessment tool for population exposure to this potent endocrine disrupting chemical.

Binding modes of environmental endocrine disruptors to human serum albumin: insights from STD-NMR, ITC, spectroscopic and molecular docking studies

Given that bisphenols have an endocrine-disrupting effect on human bodies, thoroughly exposing their potential effects at the molecular level is important. Saturation transfer difference (STD) NMR-based binding studies were performed to investigate the binding potential of two bisphenol representatives, namely, bisphenol B (BPB) and bisphenol E (BPE), toward human serum albumin (HSA). The relative STD (%) suggested that BPB and BPE show similar binding modes and orientations, in which the phenolic rings were spatially close to HSA binding site. ITC analysis results showed that BPB and BPE were bound to HSA with moderately strong binding affinity through electrostatic interactions and hydrogen bonds. The order of binding affinity of HSA for two test bisphenols is as follows: BPE > BPB. The results of fluorescence competitive experiments using 5-dimethylaminonaphthalene-1-sulfonamide and dansylsarcosine as competitors, combined with molecular docking indicated that both bisphenols are prone to attach to the binding site II in HSA. Spectroscopic results (FT-IR, CD, synchronous and 3D fluorescence spectra) showed that BPB/BPE induces different degrees of microenvironmental and conformational changes to HSA.

Bisphenol A and replacements in thermal paper: A review

Thermal paper contains potentially toxic compounds such as bisphenol A (BPA), which is used as a color developer. BPA has been reported in thermal paper in concentrations up to 42,600 μg g^-1. The exposure to BPA via dermal transfer has been recently discussed as a significant contribution to the overall human exposure and the estimated daily intake (EDI) has been reported up to 218 μg d^-1. BPA has been also detected in recycled paper with concentrations up to 46 μg g^-1. Due to the fact that BPA is a known endocrine disruptor and migrates from materials, regulatory restrictions have been established to prevent risks for the human health. As a consequence, structural analogues, such as bisphenol S (BPS) have been introduced into the market. Little is known about the presence and toxicity of these emerging replacements, and concern has risen about them. The present review gives an overview of the occurrence and levels of BPA and replacements in thermal paper. BPA is still the most common color developer found in thermal paper, followed by BPS. The analytical methods used for quantification of BPA and BPA replacements in paper products are also reviewed. BPA is transferred from thermal paper products to the finger pads upon handling it. Paper-skin transfer followed by penetration of BPA depends on conditions (e.g. greasiness of fingers and use of hand cream). It is, however, still debated whether thermal paper as a source for human exposure contributes significantly to the overall internal BPA exposure.