Identification and quantification of chlorinated bisphenol A in wastewater from wastepaper recycling plants

Synergistic endocrine disruption and cellular toxicity of polyethylene microplastics and bisphenol A in MLTC-1 cells and zebrafish

The study investigates the synergistic endocrine disruption and cellular toxicity resulting from co-exposure to polyethylene microplastics (PE-MPs) and bisphenol A (BPA) in zebrafish and MLTC-1 cells. Previous research has extensively examined the individual effects of PE-MPs and BPA on endocrine systems and cellular health. However, the specific interactions and combined toxicological impacts of these two common environmental pollutants remain underexplored, particularly in terms of their synergistic effects on endocrine pathways and cellular viability. To fill this knowledge gap, we characterized PE-MPs using scanning electron microscopy and Raman spectrometry and exposed MLTC-1 cells to PE-MPs, BPA, or combinations of both. The results showed that co-exposure to 100 µg/mL PE-MPs and 100-150 µmol/L BPA for 48 h significantly decreased cell viability, increased apoptosis rates, induced G2/M cell cycle arrest, reduced mitochondrial membrane potential, and altered the transcriptional expression of genes related to steroidogenesis. Specifically, co-exposure upregulated the Ar while downregulating Lhr and 3β-Hsd, with these effects being more pronounced than those observed with single exposures. In a complementary in vivo study, adult zebrafish were exposed to environmentally relevant concentrations of PE-MPs (1 mg/L) and BPA (1.5 µg/L) for 28 days. This co-exposure resulted in significant increases in the GSI and alterations in the gene expression associated with the HPG axis. In male zebrafish brains, genes such as Gnrh2, Esr1, and Ar were downregulated, while in female brains, Gnrh3, Esr1, and Ar also exhibited downregulation. In male testes, Star, Cyp11a1, and Hsd11b2 were upregulated, whereas Cyp19a1a, Hsd3b, Hsd20b, and Hsd17b3 were downregulated. In contrast, female ovaries showed upregulation of Cyp11a1, Cyp17, Cyp11b, Hsd3b, Hsd20b, and Hsd17b3, while Cyp19a1a was downregulated, indicating a sex-specific endocrine disruption. Overall, the findings reveal that co-exposure to PE-MPs and BPA induces synergistic toxic effects both in vitro and in vivo, which underscores the importance of studying the effects of combined pollutants to better assess environmental health risks.

Use of All-Male cyp17a1-Deficient Zebrafish (Danio rerio) for Evaluation of Environmental Estrogens

Natural and synthetic environmental estrogens (EEs) are widespread and have received extensive attention. Our previous studies demonstrated that depletion of the cytochrome P450 17a1 gene (cyp17a1) leads to all-testis differentiation phenotype in zebrafish and common carp. In the present study, cyp17a1-deficient zebrafish with defective estrogen biosynthesis were used for the evaluation of EEs, as assessed by monitoring vitellogenin (vtg) expression. A rapid and sensitive assessment procedure was established with the 3-day administration of estradiol (E2), followed by examination of the transcriptional expression of vtgs in our cyp17a1-deficient fish. Compared with the control fish, a higher E2-mediated vtg upregulation observed in cyp17a1-deficient zebrafish exposed to 0.1 μg/L E2 is known to be estrogen receptor-dependent and likely due to impaired in vivo estrogen biosynthesis. The more responsive vtg expression in cyp17a1-deficient zebrafish was observed when exposed to 200 and 2000 μg/L bisphenol A (BPA) and perfluoro-1-octanesulfonate (PFOS). The estrogenic potentials of E2, BPA, and PFOS were compared and assessed by the feminization effect on ovarian differentiation in cyp17a1-deficient zebrafish from 18 to 50 days postfertilization, based on which a higher sensitivity of E2 in ovarian differentiation than BPA and PFOS was concluded. Collectively, through the higher sensitivity to EEs and the capacity to distinguish chemicals with different estrogenic potentials exhibited by the all-male cyp17a1-deficient zebrafish with impaired estrogen biosynthesis, we demonstrated that they can be used as an excellent in vivo model for the evaluation of EEs. Environ Toxicol Chem 2024;43:1062-1074. © 2024 SETAC.

Halogenated bisphenol A derivatives potently inhibit human and rat 11β-hydroxysteroid dehydrogenase 1: Structure-activity relationship and molecular docking

Chlorinated bisphenol A (BPA) derivatives are formed during chlorination process of drinking water, whereas bisphenol S (BPS) and brominated BPA and BPS (TBBPA and TBBPS) were synthesized for many industrial uses such as fire retardants. However, the effect of halogenated BPA and BPS derivatives on glucocorticoid metabolizing enzyme 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) remains unclear. The inhibitory effects of 6 BPA derivatives in the inhibition of human and rat 11β-HSD1 were investigated. The potencies for inhibition on human 11β-HSD1 were TBBPA (IC50, 3.87 μM) = monochloro BPA (MCBPA, 4.08 μM) = trichloro BPA (TrCBPA, 4.41 μM) > tetrachloro BPA (TCBPA, 9.75 μM) > TBBPS (>100 μM) = BPS (>100 μM), and those for rat 11β-HSD1 were TrCBPA (IC50, 2.76 μM) = MCBPA (3.75 μM) > TBBPA (39.58 μM) > TCBPA = TBBPS = BPS. All these BPA derivatives are mixed/competitive inhibitors of both human and rat enzymes. Molecular docking studies predict that MCBPA, TrCBPA, TCBPA, and TBBPA all bind to the active site of human 11β-HSD1, forming hydrogen bonds with catalytic residue Ser170 except TCBPA. Regression of the lowest binding energy with IC50 values revealed a significant inverse linear regression. In conclusion, halogenated BPA derivatives are mostly potent inhibitors of human and rat 11β-HSD1, and there is structure-dependent inhibition.

Enhanced inhibition of human and rat aromatase activity by benzene ring substitutions in bisphenol A: QSAR structure-activity relationship and in silico docking analysis

Bisphenol A (BPA) is a widely used plastic material, but its potential endocrine disrupting effect has restricted its use. The BPA alternatives have raised concerns. This study aimed to compare inhibitory potencies of 11 BPA analogues on human and rat placental aromatase (CYP19A1). The inhibitory potency on human CYP19A1 ranged from bisphenol H (IC50, 0.93 μM) to tetramethyl BPA and tetrabromobisphenol S (ineffective at 100 μM) when compared to BPA (IC50, 73.48 μM). Most of them were mixed/competitive inhibitors and inhibited estradiol production in human BeWo cells. Molecular docking analysis showed all BPA analogues bind to steroid active site or in between steroid and heme of CYP19A1 and form a hydrogen bond with catalytic residue Met374. Pharmacophore analysis showed that there were 4 hydrophobic regions for BPA analogues, with bisphenol H occupying 4 regions. Bivariate correlation analysis showed that LogP (lipophilicity) and LogS (water solubility) of BPA analogues were correlated with their IC50 values. Computerized drug metabolism and pharmacokinetics analysis showed that bisphenol H, tetrabromobisphenol A, and tetrachlorobisphenol A had low solubility, which might explain their weaker inhibition on estradiol production on BeWo cells. In conclusion, BPA analogues mostly can inhibit CYP19A1 and the lipophilicity determines their inhibitory strength.

Occurrence of Chlorinated Derivatives of Bisphenol S in Paper Products and Their Potential Health Risks through Dermal Exposure

The occurrence of chlorinated derivatives of bisphenol S (Clx-BPS) and BPS was investigated in nine types of paper products (n = 125), including thermal paper, corrugated boxes, mail envelopes, newspapers, flyers, magazines, food contact paper, household paper, and business cards. BPS was found in all paper product samples, while Clx-BPS were mainly found in thermal paper (from below the limit of detection ( Collapse

Key Words

• Chlorinated derivatives of bisphenol S
• Dermal exposure
• Paper products
• Paper recycling
• Toxicity

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MESH Headings

• Humans
• Benzhydryl Compounds
• Paper
• Food
• Commerce

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Affiliation(s)

Xiaoxuan Han Research Center for Analytical Sciences, Department of Chemistry, College of Sciences, Northeastern University, Shenyang 110819, China School of Environmental & Municipal Engineering, Qingdao University of Technology, Qingdao 266033, China
Yong Tian School of Environmental & Municipal Engineering, Qingdao University of Technology, Qingdao 266033, China
Haonan Liu School of Environmental & Municipal Engineering, Qingdao University of Technology, Qingdao 266033, China
Xuwei Chen Research Center for Analytical Sciences, Department of Chemistry, College of Sciences, Northeastern University, Shenyang 110819, China
Jian-Hua Wang Research Center for Analytical Sciences, Department of Chemistry, College of Sciences, Northeastern University, Shenyang 110819, China
Jianbo Shi State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
Guibin Jiang State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China

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Selenium deficiency exacerbated Bisphenol A-induced intestinal toxicity in chickens: Apoptosis and cell cycle arrest mediated by ROS/P53

Bisphenol A (BPA) is a phenolic organic synthetic compound that is used as the raw material of polycarbonate plastics, and its safety issues have recently attracted wide attention. Selenium (Se) deficiency has gradually developed into a global disease affecting intestinal function via oxidative stress and apoptosis. However, the toxic effects and potential mechanisms of BPA exposure and Se deficiency in the chicken intestines have not been studied. In this study, BPA exposure and/or Se deficiency models were established in vivo and in vitro to investigate the effects of Se deficiency and BPA on chicken jejunum. The results showed that BPA exposure and/or Se deficiency increased jejunum oxidative stress and DNA damage, activated P53 pathway, led to mitochondrial dysfunction, and induced apoptosis and cell cycle arrest. Using protein-protein molecular docking, we found a strong binding ability between P53 and peroxisome proliferator-activated receptor γ coactivator-1, thereby regulating mitochondrial dysfunctional apoptosis. In addition, we used N-acetyl-L-cysteine and pifithrin-α for in vitro intervention and found that N-acetyl-L-cysteine and pifithrin-α intervention reversed the aforementioned adverse effects. This study clarified the potential mechanism by which Se deficiency exacerbates BPA induced intestinal injury in chickens through reactive oxygen species/P53, which provides a new idea for the study of environmental combined toxicity of Se deficiency, and insights into animal intestinal health from a new perspective.

Chronic neurotoxicity of Tetrabromobisphenol A: Induction of oxidative stress and damage to neurons in Caenorhabditis elegans

Tetrachlorobisphenol A (TCBPA) has been used as an alternative flame retardant in various fields. However, the long-term effects of TCBPA on the nervous system remain unclear. Thus, Caenorhabditis elegans (L4 larvae) were selected as a model animal to investigate the neurotoxic effects and underlying mechanisms after 10 d of TCBPA exposure. Exposure to TCBPA (0.01-100 μg/L) decreased locomotive behavior in a concentration-dependent manner. In addition, reactive oxygen species (ROS) formation and lipofuscin accumulation were significantly increased, and the expression of sod-3 was upregulated in the exposed nematodes, indicating that TCBPA exposure induced oxidative damage. Furthermore, 100 μg/L TCBPA exposure caused a reduction in dopamine and serotonin levels, and damage in dopaminergic and serotoninergic neurons, which was further confirmed by the downregulated expression of related genes (e.g., dop-1, dop-3, cat-1, and mod-1). Molecular docking analysis demonstrated the potential of TCBPA to bind to the neurotransmitter receptor proteins DOP-1, DOP-3, and MOD-1. These results indicate that chronic exposure to TCBPA induces neurotoxic effects on locomotive behavior, which is associated with oxidative stress and damage to dopaminergic and serotoninergic neurons.

Halogenated bisphenol A derivatives potently inhibit human, rat, and mouse gonadal 3β-hydroxysteroid dehydrogenases: Structure-activity relationship and in silico molecular docking analysis

Bisphenol A (BPA) is a widely used plastic material, and halogenated BPA derivatives are formed either by synthesis or environmental processes. However, the effect of halogenated bisphenols on steroidogenesis remains unclear. The aim of this study was to compare inhibition of 6 BPA derivatives on gonadal 3β-hydroxysteroid dehydrogenases (3β-HSDs) in three species (human, rat, and mouse). The inhibition on human 3β-HSD2 was tetrabromo BPA (TBBPA, IC50, 1.01 μM)>trichloro BPA (TrCBPA, 3.95 μM)>tetrachloro BPA (TCBPA, 4.14 μM)>monochloro BPA (MCBPA, 4.74 μM)>others with TrCBPA of competitive, TBBPA of noncompetitive and MCBPA/TCBPA of mixed inhibition. The inhibition on rat 3β-HSD1 was TCBPA (1.68 μM)>TrCBPA (1.72 μM)>MCBPA (2.80 μM)>BPA>others with mixed inhibition. The inhibition on mouse 3β-HSD6 was TrCBPA (1.59 μM) >MCBPA (3.36 μM)>TCBPA (3.72 μM)>others with mixed inhibition. Molecular docking analysis showed that TBBPA, TrCBPA, and TCBPA bind to steroid active sites, contacting with catalytic residue Tyr154 of human 3β-HSD2. MCBPA, TrCBPA, and TCBPA bind to steroid active site of rat 3β-HSD1. MCBPA and TrCBPA bind to active site of mouse 3β-HSD6. Regression of lowest binding energy values with Ki values revealed a significant negative linear regression (P < 0.05). In conclusion, halogenated BPA derivatives are more potent inhibitors of three 3β-HSDs than BPA and there is structure-dependent inhibition. SYNOPSIS: Chlorinated bisphenol derivatives after water chlorination process and other halogenated bisphenols effectively inhibit human and rat 3β-HSD activity, thereby leading to steroid hormone deficiency.

Quantification of the Conjugated Forms of Dichlorobisphenol A (3,3'-Cl 2 BPA) in Rat and Human Plasma Using HPLC-MS/MS

BACKGROUND

Bisphenol A (BPA) is a ubiquitous contaminant that has endocrine-disrupting effects. Chlorinated derivatives of BPA are formed during chlorination of drinking water and have higher endocrine-disrupting activity. Dichlorobisphenol A (Cl 2 BPA) is the most abundant chlorinated BPA derivative found in several human biological matrices. Recent in vitro experiments have shown that Cl 2 BPA is metabolized in sulpho- and glucuro-conjugated compounds. To date, no assay has been developed to quantify the sulfo- and glucuro-conjugates of 3,3'-Cl 2 BPA (3,3'-Cl 2 BPA-S and 3,3'-Cl 2 BPA-G, respectively).

METHODS

A high-performance liquid chromatography-tandem mass spectrometry assay for the determination of 3,3'-Cl 2 BPA conjugated forms in plasma samples was developed and validated according to the European Medicines Agency guidelines. Quantification was performed in the multiple reaction monitoring mode for all target analytes using a SCIEX 6500 + tandem mass spectrometer with an electrospray source operating in the negative ionization mode. Chromatographic separation was achieved using a C18 column maintained at 40°C and a binary mobile phase delivered in the gradient mode at a flow rate of 0.35 mL/min. Sample was prepared via simple precipitation using acetonitrile. The assay was validated and applied to rat and human plasma samples.

RESULTS

Linearity was demonstrated over the range of 0.006-25 ng/mL for 3,3'-Cl 2 BPA-G and 0.391-100 ng/mL for 3,3'-Cl 2 BPA-S. Intraday and interday bias values were in the 95%-109% range, and the imprecision <9%. Internal standard corrected matrix effects were also investigated. This method enabled quantification of the conjugated forms of 3,3'-Cl 2 BPA in plasma samples.

CONCLUSIONS

This is the first report on the development and validation of an analytical method for the quantification of 3,3'-Cl 2 BPA-G and 3,3'-Cl 2 BPA-S in the plasma matrix. This study is also the first report on the in vivo occurrence of these metabolites.

Proliferation toxicity and mechanism of novel mixed bromine/chlorine transformation products of tetrabromobisphenol A on human embryonic stem cell

Mixed bromine/chlorine transformation products of tetrabromobisphenol A (Cl_yBr_xBPAs) are mixed halogenated-type compounds recently identified in electronic waste dismantling sites. There are a lack of toxicity data on these compounds. To study their development toxicity, the proliferation toxicity was investigated using human embryonic stem cells (hESC) exposed to the lowest effective dose of two Cl_yBr_xBPA analogues (2-chloro-2',6-dibromobisphenol A and 2,2'-dichloro-6-monobromobisphenol A). For comparison, tetrabromobisphenol A, 2,2',6-tribromobisphenol A, and bisphenol A were also assessed. It was observed that Cl_yBr_xBPAs inhibited hESCs proliferation in a concentration-dependent manner. The cell bioaccumulation efficiency of Cl_yBr_xBPAs was higher than that of tetrabromobisphenol A. Also, Cl_yBr_xBPAs were more toxic than tetrabromobisphenol A, with 2,2'-dichloro-6-monobromobisphenol A exhibiting the most potent toxicity. Furthermore, flow cytometry and oxidative stress results showed that increased reactive oxygen species raised the degree of apoptosis and reduced DNA synthesis. Metabolomics analysis on the effect of Cl_yBr_xBPAs on metabolic pathway alteration showed that Cl_yBr_xBPAs mainly interfered with four metabolic pathways related to amino acid metabolism and biosynthesis. These results provide an initial perspective on the proliferation toxicity of Cl_yBr_xBPAs, indicating development toxicity in children.

Developmental toxicity of TCBPA on the nervous and cardiovascular systems of zebrafish (Danio rerio): A combination of transcriptomic and metabolomics

Tetrachlorobisphenol A (TCBPA), a widely used halogenated flame retardant, is frequently detected in environmental compartments and human samples. However, unknown developmental toxicity and mechanisms limit the entire understanding of its effects. In this study, zebrafish (Danio rerio) embryos were exposed to various concentrations of TCBPA while a combination of transcriptomics, behavioral and biochemical analyzes as well as metabolomics were applied to decipher its toxic effects and the potential mechanisms. We found that TCBPA could interfere with nervous and cardiovascular development through focal adhesion and extracellular matrix-receptor (ECM-receptor) interaction pathways through transcriptomic analysis. Behavioral and biochemical analysis results indicated abnormal swimming behavior of zebrafish larvae. Morphological observations revealed that TCBPA could cause the loss of head blood vessels. Metabolomic analysis showed that arginine-related metabolic pathways were one of the main pathways leading to TCBPA developmental toxicity. Our study demonstrated that by using omics, TCBPA was shown to have neurological and cardiovascular developmental toxicity and the underlying mechanisms were uncovered and major pathways identified.

In silico profiling of endocrine-disrupting potential of bisphenol analogues and their halogenated transformation products

Due to its endocrine-disrupting properties, bisphenol A (BPA) is being phased out from plastics, thermal paper and epoxy resins, and its replacements are being introduced into the market. Bisphenols are released into the environment, where they can undergo halogenation. Unlike BPA, the endocrine-disrupting potential of BPA analogues and their halogenated transformation products has not been extensively studied. The aim of this study was to evaluate the endocrine-disrupting potential of 18 BPA analogues and their halogenated derivatives by calculating affinities for 14 human nuclear receptors utilizing the Endocrine Disruptome and VirtualToxLab™ in silico tools. Our simulations identified AR, ERs, and GR as the most favorable targets of bisphenols and their derivatives. Several BPA analogues displayed a higher predicted potential for endocrine disruption than BPA. Our models highlighted BPZ and BPPH as the most hazardous in terms of predicted endocrine activities. Halogenation, in general, was predicted to increase the binding affinity of bisphenols for AR, ERβ, MR, GR, PPARγ, and TRβ. Notably, mono- or 2,2'-di-halogenated bisphenols exhibited the highest potential for endocrine disruption. In vitro corroboration of the obtained results should be the next milestone in evaluating the safety of BPA substitutes and their halogenated transformation products.

Performance and mechanism of a novel S-scheme heterojunction sonocatalyst CuS/BaWO4 for degradation of bisphenol A by ultrasonic activation

A novel CuS/BaWO₄ heterojunction catalyst was prepared and characterized. Taking bisphenol A as the target pollutant for catalytic degradation, the sonocatalytic activity of CuS/BaWO₄ composite was evaluated, and the combination with persulfate improved the sonocatalytic degradation of bisphenol A. The results showed that CuS/BaWO₄ composite had good sonocatalytic degradation activity for bisphenol A, and the degradation rate was 70.99% ± 1.46%. After combined with persulfate, the degradation rate was further increased to 95.34% ± 0.10%, and the reaction time was relatively shortened. The results of the trapping experiment and calculated energy band positions showed that the formation of S-scheme heterojunction and the formation of hydroxyl radicals and holes were the key to the catalytic degradation of bisphenol A by CuS/BaWO₄ composite. In this study, a new CuS/BaWO₄ heterojunction sonocatalyst was synthesized. The catalyst can efficiently remove bisphenol A from the water environment and can be used as a potential solution for endocrine disruptor pollution in the water environment.

Environmental contamination status with common ingredients of household and personal care products exhibiting endocrine-disrupting potential

The continuous use of household and personal care products (HPCPs) produces an immense amount of chemicals, such as parabens, bisphenols, benzophenones and alkylphenol ethoxylates, which are of great concern due to their well-known endocrine-disrupting properties. These chemicals easily enter the environment through man-made activities, thus contaminating the biota, including soil, water, plants and animals. Thus, on top of the direct exposure on account of their presence in HPCPs, humans are also susceptible to secondary indirect exposure attributed to the ubiquitous environmental contamination. The aim of this review was therefore to examine the sources and occurrence of these noteworthy contaminants (i.e. parabens, bisphenols, benzophenones, alkylphenol ethoxylates), to summarise the available research on their environmental presence and to highlight their bioaccumulation potential. The most notable environmental contaminants appear to be MeP and PrP among parabens, BPA and BPS among bisphenols, BP-3 among benzophenones and NP among alkylphenols. Their maximum detected concentrations in the environment are mostly in the range of ng/L, while in human tissues, their maximum concentrations achieved μg/L due to bioaccumulation, with BP-3 and nonylphenol showing the highest potential to bioaccumulate. Finally, of another great concern is the fact that even the unapproved parabens and benzophenones have been detected in the environment.

Analytical method for the biomonitoring of bisphenols and parabens by liquid chromatography coupled to tandem mass spectrometry in human hair

Bisphenols and parabens are endocrine disruptors families widely used in daily life. They are known to be linked to numerous pathologies such as reproductive disorders, obesity, breast cancer, hypertension and asthma. Biomonitoring is an essential tool for assessing population exposure to environmental pollutants. Blood and urine are the main matrices used in human biomonitoring. However, they are not suitable to evaluate long-term exposure to endocrine disruptors with a short elimination half-life such as parabens or phenols. Hair appears to be an interesting alternative matrix allowing a wide window of exposure due to an accumulation of xenobiotics during hair growth. This study presents the development and validation of a high-performance liquid chromatography coupled to tandem mass spectrometry for the simultaneous determination of bisphenol A, its chlorinated derivatives, bisphenol F, bisphenol S and parabens in human hair. An optimised sample preparation based on acidic hydrolysis followed by liquid-liquid extraction was performed, before an analysis by ultra-high performance liquid chromatography coupled to tandem mass spectrometry in multiple reaction monitoring mode. To validate the method, recognized bioanalytical guidelines were used and calibration and quality control samples were prepared in human hair samples. Linearities were over 0.996 in the whole range of concentrations. Trueness and precision were demonstrated for each target analyte with intra-day and inter-day bias values ranging from 86 % to 118 % and relative standard deviation values ranging from 0 % to 19 %. At the same time, limits of quantification were set at 0.25 ng/g for bisphenol A and parabens, 0.05 ng/g for bisphenols F and S and 0.00625 ng/g for the chlorinated derivatives of bisphenol A. This reliable method was applied to hair samples taken from hospital professionals and allowed the quantification of these endocrine disruptors in this population. Chlorinated derivatives of bisphenol A were quantified here in hair for the first time.

Halogenated ingredients of household and personal care products as emerging endocrine disruptors

The everyday use of household and personal care products (HPCPs) generates an enormous amount of chemicals, of which several groups warrant additional attention, including: (i) parabens, which are widely used as preservatives; (ii) bisphenols, which are used in the manufacture of plastics; (iii) UV filters, which are essential components of many cosmetic products; and (iv) alkylphenol ethoxylates, which are used extensively as non-ionic surfactants. These chemicals are released continuously into the environment, thus contaminating soil, water, plants and animals. Wastewater treatment and water disinfection procedures can convert these chemicals into halogenated transformation products, which end up in the environment and pose a potential threat to humans and wildlife. Indeed, while certain parent HPCP ingredients have been confirmed as endocrine disruptors, less is known about the endocrine activities of their halogenated derivatives. The aim of this review is first to examine the sources and occurrence of halogenated transformation products in the environment, and second to compare their endocrine-disrupting properties to those of their parent compounds (i.e., parabens, bisphenols, UV filters, alkylphenol ethoxylates). Albeit previous reports have focused individually on selected classes of such substances, none have considered the problem of their halogenated transformation products. This review therefore summarizes the available research on these halogenated compounds, highlights the potential exposure pathways, and underlines the existing knowledge gaps within their toxicological profiles.

Unravelling the molecular mechanism of mutagenic factors impacting human health

Environmental mutagens are chemical and physical substances in the environment that has a potential to induce a wide range of mutations and generate multiple physiological, biochemical, and genetic modifications in humans. Most mutagens are having genotoxic effects on the following generation through germ cells. The influence of germinal mutations on health will be determined by their frequency, nature, and the mechanisms that keep a specific mutation in the population. Early prenatal lethal mutations have less public health consequences than genetic illnesses linked with long-term medical and social difficulties. Physical and chemical mutagens are common mutagens found in the environment. These two environmental mutagens have been associated with multiple neurological disorders and carcinogenesis in humans. Thus in this study, we aim to unravel the molecular mechanism of physical mutagens (UV rays, X-rays, gamma rays), chemical mutagens (dimethyl sulfate (DMS), bisphenol A (BPA), polycyclic aromatic hydrocarbons (PAHs), 5-chlorocytosine (5ClC)), and several heavy metals (Ar, Pb, Al, Hg, Cd, Cr) implicated in DNA damage, carcinogenesis, chromosomal abnormalities, and oxidative stress which leads to multiple disorders and impacting human health. Biological tests for mutagen detection are crucial; therefore, we also discuss several approaches (Ames test and Mutatox test) to estimate mutagenic factors in the environment. The potential risks of environmental mutagens impacting humans require a deeper basic knowledge of human genetics as well as ongoing research on humans, animals, and their tissues and fluids.

Tetrachlorobisphenol A mediates reproductive toxicity in Caenorhabditis elegans via DNA damage-induced apoptosis

Tetrachlorobisphenol A (TCBPA), an alternative to tetrabromobisphenol A (TBBPA), is ubiquitous in the environment and could potentially impact the reproductive system of organisms. However, the mechanisms underlying TCBPA-mediated reproductive effects remain unclear. Herein, we exposed Caenorhabditis elegans (C. elegans, L4 larvae) to TCBPA at environmentally relevant doses (0-100 μg/L) for 24 h. Exposure to TCBPA at concentrations of 1-100 μg/L impaired fertility of C. elegans, as indicated by brood size. After staining, the number of germline cells decreased in a dose-dependent manner, whereas germline cell corpses increased in exposed nematodes (10-100 μg/L TCBPA). Moreover, the expression of genes related to the germline apoptosis pathway was regulated following exposure to 100 μg/L TCBPA, indicating the potential role of DNA damage in TCBPA-induced apoptosis. Apoptosis was nearly abolished in ced-4 and ced-3 mutants and blocked in hus-1, egl-1, cep-1, and ced-9 mutants. Numerous foci were detected in TCBPA (100 μg/L)-exposed hus-1::GFP strains. These results indicate that TCBPA induces hus-1-mediated DNA damage and further causes apoptosis via a cep-1-dependent pathway. Our data provide evidence that TCBPA causes reproductive toxicity via DNA damage-induced apoptosis.

Bisphenol A exposure induces neurobehavioral deficits and neurodegeneration through induction of oxidative stress and activated caspase-3 expression in zebrafish brain

Bisphenol A (BPA) is noted for its adversative effects by inducing oxidative stress, carcinogenicity, neurotoxicity, inflammation, etc. However, the likely act of BPA in inducing neurodegenerative phenotypes remains elusive in the available literature. Hence, the present study was conducted to decipher the neurodegenerative potential of BPA in inducing Parkinson's disease like phenotypes in zebrafish. Zebrafish were subjected to chronic waterborne exposure to BPA for 56 days. Locomotor activities and neurobehavioral response were assessed by the NTDT (novel tank diving test), OFT (open field test), and LDPT (light-dark preference test). The oxidative stress markers and histopathological observation for pyknosis and chromatin condensation were carried out. Immunohistochemistry for activated caspase-3 and targeted proteins expression study was performed. The basic findings reveal that chronic BPA exposure significantly induces locomotor dysfunction through a significant decline in mean velocity and total distance traveled. As a measure of pyknosis and chromatin condensation, pyknotic and Hoechst positive neurons in telencephalon and diencephalon significantly increased by BPA exposure. A higher concentration of BPA adversely affects the neurobehavioral response, antioxidant status, and neuromorphology in zebrafish. Parkinson-relevant targeted protein expression viz. alpha-synuclein and LRRK2, were significantly upregulated, whereas tyrosine hydroxylase, NeuN, and Nurr1 were significantly downregulated in the zebrafish brain. As an indicator of cell death by apoptosis, the expression of activated caspase-3 was significantly increased in the BPA-exposed zebrafish brain. These basic results of the current study indicate that chronic waterborne exposure to BPA induces neuropathological manifestation leading to the development of motor dysfunction and Parkinsonism-like neurodegenerative phenotypes in zebrafish.

An overview of the literature on emerging pollutants: Chlorinated derivatives of Bisphenol A (ClxBPA)

CONTEXT

Bisphenol A (BPA) is a ubiquitous contaminant with endocrine-disrupting effects in mammals. During chlorination treatment of drinking water, aqueous BPA can react with chlorine to form chlorinated derivatives of BPA (mono, di, tri and tetra-chlorinated derivatives) or Cl_xBPA.

OBJECTIVE

The aim of this study is to summarize and present the state of knowledge on human toxicological risk assessment of Cl_xBPA.

MATERIALS AND METHODS

A search on Cl_xBPA in the PubMed database was performed based on studies published between 2002 and 2021. Forty-nine studies on chlorinated derivatives of BPA were found. Available information on their sources and levels of exposure, their effects, their possible mechanisms of action and their toxicokinetics data was extracted and presented.

RESULTS

Cl_xBPA have been essentially detected in environmental aqueous media. There is evidence in toxicological and epidemiological studies that Cl_xBPA also have endocrine-disrupting capabilities. These emerging pollutants have been found in human urine, serum, breast milk, adipose and placental tissue and can constitute a risk to human health. However, in vitro and in vivo toxicokinetic data on Cl_xBPA are scarce and do not allow characterization of the disposition kinetics of these compounds.

CONCLUSION

More research to assess their health risks, specifically in vulnerable populations, is needed. Some water chlorination processes are particularly hazardous, and it is important to evaluate their chlorination by-products from a public health perspective.

Immunohistochemical expression of aromatase cyp19a1a and cyp19a1b in the ovary and brain of zebrafish (Danio rerio) exposed to different concentrations of bisphenol A

Bisphenol A (BPA) is used to produce plastic and plastic derived products in multitude of daily utensils, being one of the industrial compounds most widely used. This endocrine disrupting chemical (EDCs) is a well-known environmental pollutant released into the aquatic environment from industrial wastewater, sewage sludge or landfill leachate. Aromatases are considered potential targets of EDCs with characteristics that make them suitable biomarkers of exposure to their effects. The main objective of our study was to evaluate the expression of cyp19a aromatase as a toxicological endpoint after BPA exposure through the identification and assessment of alterations of the main cells responsible for cyp19a1a and cyp19a1b expression in the zebrafish ovary and brain using different concentrations of BPA in water. Immunohistochemistry was used to analyze the expression of these enzymes in female zebrafish exposed and not exposed to different concentrations of BPA (1, 10, 100 and 1000 μg / L) in water (n = 6/group) for 14 days. The results obtained in this study showed that the cyp19a aromatase system, involved in the synthesis of steroid compounds, is specially located in distinct oocyte stages in the ovary (cyp19a1a) and in radial glial cells of the brain (cyp19a1b). An overexpression of these aromatases was observed after BPA exposure in zebrafish, peaking from a concentration of 10 µg/L and showing to be good biomarkers of exposure to identify the early effects of low BPA concentrations. To our knowledge, this study is the first to localize and quantify the expression of cyp19a1a and cyp19a1b in the cells of brain and ovary after fish exposure to different BPA concentrations in water.

Exploring the genotoxicity triggers in the MP UV/H2O2-chloramination treatment of bisphenol A through bioassay coupled with non-targeted analysis

Bisphenol A (BPA) is a well-known xenoestrogen, and UV/H₂O₂ advanced oxidation process (AOP) is one of the most effective technologies to remove BPA from water. Using BPA spiked tap water, a batch-scale photochemical experiment was conducted to investigate whether BPA can pose a genotoxicity concern during the medium pressure (MP) UV/H₂O₂ treatment and the post-chloramination. Samples at different UV exposure and post-chloramination durations were collected and analyzed by CALUX® gene reporter assays regarding estrogen receptor α (ERα) and p53 transcriptional activity. MP UV/H₂O₂ process did not cause extra estrogenic effects from the degradation of BPA, whereas genotoxicity occurred when the treated water was exposed with monochloramine. Seven frequently reported nitrogenous disinfection byproducts (N-DBPs) were detected, but none of them were responsible for the observed genotoxicity. Employed with gas chromatography-quadrupole time-of-flight mass spectrometry (GC-QTOF-MS), four compounds possibly contributed to the genotoxicity were tentatively identified and two of them with aminooxy- or cyano- group were considered as "new" N-DBPs. This study demonstrated that by-products differ from their parent compounds in toxicity can be formed in the UV oxidation with post-disinfection process, which should become a cause for concern.

Bioaccumulation and reproductive toxicity of bisphenol A in male-pregnant seahorse (Hippocampus erectus) at environmentally relevant concentrations

Seahorses, with brood pouch in adult males, are a bioindicator species that exhibit specialized reproductive strategy of "male pregnancy". Bisphenol A (BPA), one of the most pervasive endocrine-disrupting chemicals (EDCs), is hazardous for reproductive, immune, and neurological systems. However, no evidence of BPA toxicity to the male-pregnant animals is available. Herein, the reproductive toxicity of BPA was evaluated in lined seahorses (Hippocampus erectus) following exposure to environmentally relevant concentrations (10, 100, and 1000 μg/L) through physiological, histological, and transcriptional analyses. Our results indicated BPA bioaccumulation to be positively correlated with exposure doses in both sexes. Ovarian failure was only observed in the high-dose BPA treatment group, accompanied by the apoptosis of follicular cells and up-regulation of pro-apoptotic genes. However, brood pouches maintenance were surprisingly inhibited at low concentration, and transcriptomic analysis revealed disturbed profiles of genes involved in the extracellular matrix and cell-cell adhesion pathways. Interestingly, seahorse testes were less sensitive to BPA exposure than that in other teleosts. Thus, our study suggests that BPA at environmentally relevant concentrations might cause reproductive dysfunction in seahorses, potentially exerting adverse effects on the seahorse population since most of them inhabit shallow coastal areas with prevalent estrogenic contaminants.

New Mixed Bromine/Chlorine Transformation Products of Tetrabromobisphenol A: Synthesis and Identification in Dust Samples from an E-Waste Dismantling Site

The large-scale production and usage of tetrabromobisphenol A (TBBPA) and its analogues have caused widespread contamination, raising concern about their potential endocrine disruption effects on both humans and ecosystems. In the present study, debromination and unknown mixed bromine/chlorine transformation products of TBBPA (X-BBPA) were screened in dust samples from an e-waste dismantling site. Five monochloro products (2-chloro-2',6,6'-TriBBPA, 2-chloro-2',6-DiBBPA, 2-chloro-2',6'-DiBBPA, 2-chloro-2'-MoBBPA, and 2-chloro-6-MoBBPA) and two dichloro products (2,2'-dichloro-6,6'-DiBBPA and 2,2'-dichloro-6-MoBBPA) were successfully synthesized and structurally identified. TBBPA and its transformation products were detected by comparison of their mass spectra and retention times with those of synthetic standards. The mean concentration of X-BBPA was 1.63 × 10⁴ ng/g in e-waste dismantling workshop dust samples based on dry weight, which was at a similar level to TBBPA. However, it was 1 order of magnitude lower than the concentrations of the debromination congeners. Thus, both debromination and chlorine-bromine exchange may be important reactions during the thermal processing of e-waste. The results on mixed chlorinated/brominated TBBPA transformation products provided new insights into TBBPA transformation. The elevated levels of the transformation products of TBBPA suggested that these products should be targeted to avoid underestimation of possible health risks.

Formation and enhanced photodegradation of chlorinated derivatives of bisphenol A in wastewater treatment plant effluent

There are many reports on the detection and removal of emerging pollutants in the wastewater effluents, while the fate of their chlorinated derivatives generated during chlorination is not well understood. Here we investigated the photodegradation of chlorinated derivatives of bisphenol A (CDBPAs), mainly including 3-chlorobisphenol A, 3,3'-dichlorobisphenol A, 3,5-dichlorobisphenol A, 3,3',5-trichlorobisphenol A, and 3,3',5,5'-tetrachlorobisphenol A, under simulated sunlight. Distinct from BPA, CDBPAs underwent rapid direct photodegradation due to a pronounced bathochromic shift of UV absorption. The photodegradation of CDBPAs was significantly enhanced by effluent organic matter (EfOM) from the wastewater effluent. A series of quenching experiments and laser flash photolysis analysis verified the contribution of triplet states of EfOM (³EfOM∗) for the indirect photodegradation of CDBPAs with rate constant of ∼10⁹ M^-1 s^-1. Both direct and EfOM-induced indirect photodegradation of CDBPAs increased with a higher degree of chlorination. Furthermore, high-resolution mass spectrometry showed similar photoproducts for direct and indirect photodegradation of CDBPAs, mainly ascribed to the cleavage of C-Cl bond and hydroxylation with further cleavage of the benzene ring. The estrogenic activity of the photoproducts was diminished. These findings suggest that photodegradation is an important pathway for the removal and detoxication of CDBPAs from effluents and receiving natural waters under sunlight.

In vitro evaluation of the hepatic lipid accumulation of bisphenol analogs: A high-content screening assay

Bisphenol A (BPA) has a variety of adverse effects on human health; therefore, BPA analogs are increasingly used as replacements. Notably, recent studies have revealed that BPA exposure induced hepatic lipid accumulation, but few studies are available regarding the similar effects of other bisphenol analogues (BPs). Thus, in the present study, a high-content screening (HCS) assay was performed to simultaneously evaluate the hepatic lipid accumulation of 13 BPs in vitro. The BPs induced lipid deposition in HepG2 cells ranking as below: 4,4'-thiodiphenol (TDP) < bisphenol S (BPS) < 4,4'-dihydroxybenzophenone (DHBP) < tetrabromobisphenol A (TBBPA) < tetrachlorobisphenol A (TCBPA) < bisphenol E (BPE) < bisphenol F (BPF) < bisphenol B (BPB) < bisphenol AF (BPAF) < bisphenol A (BPA) < bisphenol C (BPC) < tetramethylbisphenol A (TMBPA) < bisphenol AP (BPAP). Meanwhile, Oil Red O staining and triacylglycerol detection further validated the lipid accumulation elicited by the latter 8 BPs, which exhibited the more significant effects on lipid deposition. Mechanistically, significantly increased expressions of genes involved in fatty acid synthesis and nuclear receptors and decreased levels of genes associated with fatty acid β-oxidation were observed under BPs treatment. Therefore, the present work is the first to systematically provide direct evidence for BPs-induced hepatic lipid accumulation in vitro via HCS, which can be helpful for safety assessments of BPs.

Environmental estrogen exposure converts lipid metabolism in male fish to a female pattern mediated by AMPK and mTOR signaling pathways

Environmental estrogens, including bisphenol A (BPA) and 17β-estradiol (E2), which are widely used in industries and medicine, pose a severe ecological threat to fish due to feminization induction. However, the related metabolic basis for reproductive feminization in male fish has not been well addressed. We first found that female zebrafish exhibited higher lipid accumulation and lipogenesis activity than males. Next, we exposed male and female zebrafish to E2 (200 ng/L) or BPA (100 μg/L) for six weeks, and observed an early-phase reproductive feminization in males, accompanied with reduced spermatids, significant fat deposition and lipogenic gene expressions that mimicked female patterns. Cellular signaling assays revealed that, E2 or BPA modulated lipid metabolism in males mainly through lowering 5' AMP-activated protein kinase (AMPK) and upregulating the lipogenic mechanistic target of rapamycin (mTOR) pathways. For the first time, we show that environmental estrogens could alter lipid metabolism in male fish to a female pattern (metabolic feminization) prior to gonad feminization in male fish, to allows males to accumulate efficiently lipids to harmonize with the feminized gonads. This study suggests that negative effects of environmental estrogens, as hazardous materials, on vertebrate health are more complicated than originally thought.

Bisphenol A, Chlorinated Derivatives of Bisphenol A and Occurrence of Myocardial Infarction in Patients with Type 2 Diabetes: Nested Case-Control Studies in Two European Cohorts

A positive association between Bisphenol A (BPA) exposure and coronary heart disease has been shown, but not in patients with type 2 diabetes (T2D). During the treatment of drinking water, chlorination leads to the formation of chlorinated derivatives of Bisphenol A (ClxBPA), that have higher estrogenic activity than BPA. No evidence exists for a relationship between exposure to ClxBPA and myocardial infarction in patients with T2D. The objective of this study was to evaluate the relationship between exposure to BPA, ClxBPA and the occurrence of myocardial infarction (MI) in patients with T2D. Two nested case-control studies in two independent European cohorts were performed. Each case with incident MI during follow-up was matched to one control on age, sex, and personal cardiovascular history in the same cohort. Association between baseline urine concentrations of BPA and of ClxBPA and incident MI was determined. Exposure to BPA was 31% in the ESTHER cohort and 18% in the SURDIAGENE cohort. In a meta-analysis of the two studies, occurrence of MI was significantly associated with urine BPA detection: adjusted OR = 1.97 (1.05-3.70), p = 0.04. Exposure to ClxBPA significantly differed in the SURDIAGENE and ESTHER studies: 24% and 8%, respectively (p = 0.0003). It was very strongly associated with MI in the SURDIAGENE cohort with an adjusted odds ratio (OR) of 14.15 (2.77-72.40) but this association was not replicated in the ESTHER study: adjusted OR: 0.17 (0.02-1.23). Whether these results may be explained by different water chlorination processes in France and Germany, resulting in different ClxBPA exposure levels, requires further investigation.

Synthesis and characterization of polyaniline, polypyrrole and zero-valent iron-based materials for the adsorptive and oxidative removal of bisphenol-A from aqueous solution

One pot synthesis of a polypyrrole, polyaniline and Fe0 nano-composite (Fe0-PPY/PANI) was achieved by polymerizing aniline and pyrrole with FeCl3 followed by the reduction of Fe3+ to Fe0 with NaBH4. PPY/PANI was synthesized the same way as Fe0-PPY/PANI, except that all the FeCl3 was removed by rinsing. The presence of Fe0 was demonstrated using several analytical techniques; this was shown in comparison to materials that are without Fe0. A series of materials were screened as both adsorbents and catalyst for the activation of H2O2 towards bisphenol A (BPA) removal in batch experiments. Polymers performed better than composites containing Fe0 at adsorption, whereas Fe0 based materials were better catalysts for the activation of H2O2. BPA samples were then spiked with other contaminants including sewage water to test the performance of the various adsorbents and Fenton catalysts. PPY/PANI was found to be a better adsorbent than the rest, whereas Fe0-PPY/PANI was the best Fenton catalyst. The adsorption kinetics of BPA onto PPY/PANI was studied; it was found that the process was governed by the pseudo-second-order kinetic model. The adsorption isotherms revealed that the amount of BPA taken up by PPY/PANI increased with increasing temperature and was governed by the Langmuir adsorption isotherm. The mechanism in which Fe0-PPY/PANI and H2O2 degraded BPA was studied, it was found that surface-bound hydroxyl radicals were responsible for the degradation of BPA. It was also shown that the degradation process included the formation of smaller compounds leading to the reduction of the total organic content by 57%.

The utility of vitellogenin as a biomarker of estrogenic endocrine disrupting chemicals in molluscs

Estrogenic endocrine disrupting chemicals (EDCs) are natural hormones, synthetic compounds or industrial chemicals that mimic estrogens due to their structural similarity with estrogen's functional moieties. They typically enter aquatic environments through wastewater treatment plant effluents or runoff from intensive livestock operations. Globally, most natural and synthetic estrogens in receiving aquatic environments are in the low ng/L range, while industrial chemicals (such as bisphenol A, nonylphenol and octylphenol) are present in the μg to low mg/L range. These environmental concentrations often exceed laboratory-based predicted no effect concentrations (PNECs) and have been evidenced to cause negative reproductive impacts on resident aquatic biota. In vertebrates, such as fish, a well-established indicator of estrogen-mediated endocrine disruption is overexpression of the egg yolk protein precursor vitellogenin (Vtg) in males. Although the vertebrate Vtg has high sensitivity and specificity to estrogens, and the molecular basis of its estrogen inducibility has been well studied, there is growing ethical concern over the use of vertebrate animals for contaminant monitoring. The potential utility of the invertebrate Vtg as a biomonitor for environmental estrogens has therefore gained increasing attention. Here we review evidence providing support that the molluscan Vtg holds promise as an invertebrate biomarker for exposure to estrogens. Unlike vertebrates, estrogen signalling in invertebrates remains largely unclarified and the classical genomic pathway only partially explains estrogen-mediated activation of Vtg. In light of this, in the latter part of this review, we summarise recent progress towards understanding the molecular mechanisms underlying the activation of the molluscan Vtg gene by estrogens and present a hypothetical model of the interplay between genomic and non-genomic pathways in the transcriptional regulation of the gene.

Transformation of endocrine disrupting chemicals, pharmaceutical and personal care products during drinking water disinfection

Pharmaceuticals and personal care products (PPCPs) and endocrine disrupting compounds (EDCs) are frequently detected in drinking water sources. This raises concerns about the formation of potentially more toxic transformation products (TPs) after drinking water disinfection. This study applied a combination of computational and experimental methods to investigate the biological activity of eight EDCs and PPCPs commonly detected in source waters (acetaminophen, bisphenol A, carbamazepine, estrone, 17α-ethinylestradiol, gemfibrozil, naproxen and triclosan) before and after disinfection. Using a Stepped Forced Molecular Dynamics (SFMD) method, we detected 911 unique TPs, 36% of which have been previously reported in the scientific literature. We calculated the likelihood that TPs would cause damage to biomolecules or DNA relative to the parent compound based on lipophilicity and the occurrence of structural alerts, and applied two Quantitative Structure-Activity Relationship (QSAR) tools to predict toxicity via receptor-mediated effects. In parallel, batch experiments were performed with three disinfectants, chlorine, chlorine dioxide and chloramine. After solid-phase extraction, the resulting TP mixtures were analyzed by chemical analysis and a battery of eleven in vitro bioassays covering a variety of endpoints. The laboratory results were in good agreement with the predictions. Overall, the combination of computational and experimental chemistry and toxicity methods used in this study suggest that disinfection of the studied EDCs and PPCPs will produce a large number of TPs, which are unlikely to increase specific toxicity (e.g., endocrine activity), but may result in increased reactive and non-specific toxicity.

Assessment of bisphenol A alternatives in paper products from the Chinese market and their dermal exposure in the general population

Bisphenol A (BPA), a well-known endocrine disruptor, is used as a color developer in thermal paper. More recently, some emerging structural analogues have been introduced to replace BPA due to the strengthened regulations concerning thermal paper. Nevertheless, very limited data are available regarding their occurrence and potential health risks. Here, thirteen potentially toxic compounds were investigated in paper products (120 thermal papers and 81 nonthermal papers) collected in Beijing, China. The results indicated that the replacement of BPA by alternatives such as Bisphenol S (BPS), Bis(2-chloroethyl)ether-4,4″-dihydroxydiphenyl sulfone copolymer (D-90), 4-hydroxyphenyl 4-isoprooxyphenylsulfone (D-8), Bis(4-hydroxyphenyl)sulfonylphenyl (BPS-MAE) and Bis-(3-allyl-4-hydroxyphenyl) sulfone (TGSA) has been significantly advanced in several types of thermal paper (i.e., market weight stickers, train tickets, express labels, air boarding passes and lottery tickets). The mean value for the total analyte concentrations in thermal paper was 6.06 mg/g, and the highest level found was 26.0 mg/g. In addition, the frequent detection of these chemicals in nonthermal paper (>80%, n = 81) demonstrated that the contamination in thermal paper can be spread into other recycled paper, such as corrugated boxes, newspapers, food contact papers, etc. The estimated daily intake of BPA and its alternatives through the handling of thermal paper was 0.025 μg/kg bw/day for the general population. This is the first report on the occurrence of various new BPA alternatives in paper products from China, which will be helpful for further risk assessment and making responsible replacement decisions.

Chlorinated and brominated bisphenol A derivatives: Synthesis, characterization and determination in water samples

Bisphenol A (BPA) has been used in the plastics industry for several decades. During the treatment of drinking water with chlorine reagent, the formation of chlorinated derivatives of BPA (ClxBPA) but also bromoBPA and bromochloroBPA is to be expected. Some of these compounds are considered to have an estrogenic effect and could induce major risks for human health by targeting different organs and systems in the body. In this paper, we describe the synthesis of chloro- and bromobisphenol A (ClxBPA, BrxBPA, BrxClxBPA)and their analytical characterization. These derivatives could be used as analytical standards in LC-MS/MS or evaluated in in vitro biological tests for their potential as endocrine disruptors. In this study, we evaluated the presence of BPA, ClxBPA in a pilot study from water samples. Range values found for BPA, ClxBPA were respectively 2.8-4169.3 ng/L and 0.8-11.3 ng/L.

Effect of activated carbon on removal of four phenolic endocrine-disrupting compounds, bisphenol A, bisphenol F, bisphenol S, and 4-tert-butylphenol in constructed wetlands

We investigated the effects of activated carbon, used as constructed wetlands (CWs) medium, on its ability to remove four emerging endocrine-disrupting chemicals (EDCs): bisphenol A (BPA), bisphenol F (BPF), bisphenol S (BPS) and 4-tert-butylphenol (4-tert-BP). Two types of CWs planted with common reed were constructed, one with pumice rock called normal CW and the other was amended with activated carbon (AC) called AC-CW. EDCs contaminated synthetic wastewater (5 mg/L of each) was treated by CWs for 8 weeks. AC-CW completely and sustainably removed all four EDCs (98-100%) starting immediately and continuing throughout the experiment. Removal performances of all EDCs by AC-CW were significantly higher than those by normal CW. After experiment, no BPA and BPF and very small amounts of BPS and 4-tert-BP were detected in AC. In AC-CW, final elimination step of EDCs might be biodegradation. In addition, bacterial populations on AC component of AC-CW were one-two orders higher than those on the pumice rock of normal CW. Therefore, in AC-CW, EDCs were initially adsorbed onto AC, where they could be effectively degraded by high bacterial population.

Occurrence, endocrine-related bioeffects and fate of bisphenol A chemical degradation intermediates and impurities: A review

In recent decades, increasing attention has been directed toward the effects of bisphenol A (BPA) as an environmental pollutant, primarily due to its demonstrated endocrine-disruptive effects. A growing body of evidence indicates that many BPA derivatives also exhibit endocrine activity and other adverse biological properties. A review of the published literature was performed to identify BPA degradation intermediates resulting from chemical degradation processes of BPA, as well as BPA's associated co-pollutants. Products of biological metabolism were not included in this study. Seventy-nine chemicals were identified. Of these chemicals, a subset - those containing two 6-membered aromatic rings connected by a central ring-linking carbon - was identified, and a further literature review was conducted to identify demonstrated biological effects associated with the chemicals in this subset. The objectives of this review were to assess the potential risks to human and environmental health associated with BPA derivatives, characterize our current understanding of BPA's degradation intermediates and co-pollutants, and aid in the identification of compounds of interest that have received insufficient scrutiny.

Bacteria enhanced lignocellulosic activated carbon for biofiltration of bisphenols in water

There are eight bisphenol analogues being identified and characterized; among them, bisphenol A (BPA) is on the priority list on the basis of its higher level of uses, occurrence, and toxicity. The endocrine system interfered by BPA has been inventoried as it has the same function as the natural hormone 17β-estradiol and binds mainly to the estrogen receptor (ER) to exhibit estrogenic activities. The BPA concentration in surface waters (14-1390 ng/L) in many parts of the world, such as Japan, Korea, China, and India, was also a significant concern. Research efforts are focusing on restricting BPA consumption as well as removing BPA in our environment especially in drinking water. Current opinion is that lignocellulosic activated carbon stimulated with BPA-degrading bacteria could have the potential to provide solution for recent challenges faced by water utilities arising from BPA contamination in water. This technology has some new trends in the low-cost biofiltration process for removing BPA. This review is to provide in-depth discussion on the fate of BPA in our ecosystem and underlines methods to enhance the efficacy of activated carbon in the presence of BPA-degrading bacteria in the biofiltration process.

Individual and binary mixture effects of bisphenol A and lignin-derived bisphenol in Daphnia magna under chronic exposure

In recent years, many new chemicals have been synthesized from biomass with an aim for sustainable development by replacing the existing toxic chemicals with those having similar properties and applications. However, the effects of these new chemicals on aquatic organisms remain relatively unknown. In this study, the effects of bisphenol A (BPA) and lignin-derived bisphenol (LD-BP, a BPA analogue) on Daphnia magna were evaluated. The animals were exposed to BPA, LD-BP, and their binary mixture at concentrations (2-2000 μg L^-1) for 21 days. The expression of various biochemical markers and the effects on growth, molting, and reproduction parameters were examined. The results showed that the weight of daphnids significantly increased after exposure to BPA, LD-BP, and the binary mixture relative to that of the control animals. The activity of superoxide dismutase was significantly inhibited by LD-BP and the binary mixture. At the highest exposure concentration of the binary mixture, the activities of acetylcholinesterase and α-glucosidase, fecundity, and the number of neonates per brood were significantly altered. Our results showed that the effects of BPA and LD-BP on D. magna were generally comparable, except for the effect on the weight at their environmentally relevant concentrations (e.g., <20 μg L^-1). The effects on the reproduction of D. magna could be mainly due to the shift in energy redistribution under BPA and LD-BP exposures. Our results implied that exposures to both BPA and LD-BP could potentially cause deleterious effects at the population level in D. magna.

Different effects of bisphenol a and its halogenated derivatives on the reproduction and development of Oryzias melastigma under environmentally relevant doses

Bisphenol A (BPA) and its halogenated compounds (H-BPAs) are widely detected in the environmental media and organisms. However, their toxicological effects, especially chronic exposure at low doses, have not been fully compared. In this study, the effects of BPA and H-BPAs on the reproduction and development of Oryzias melastigma were systematically assessed and compared at various developmental stages. BPA and its derivatives tetrabromobisphenol A (TBBPA) and tetrachlorobisphenol A (TCBPA) elicited the acceleration of embryonic heartbeat. BPA did not show any significant impact on the hatching time and rate of embryos. In contrast, both TBBPA and TCBPA led to the delayed hatching and decreased hatching rate. Accordingly, the expressions of hatching enzyme significantly decreased upon exposure and TCBPA was found to be more toxic than TBBPA. The body weight and gonadsomatic index (GSI) of the treated fish were relatively lower than the control fish upon long-term (four months from larvae to adult) exposure to BPA rather than H-BPAs. Slowed oocyte development occurred in the ovary, and the estrogen level decreased after exposure to BPA rather than H-BPAs. In male fish, no significant alteration was observed in the testis for all groups. The concentration of testosterone significantly decreased upon exposure to BPA rather than H-BPAs. The effects of these three chemicals on the estrogen-related gene expressions were different under various developmental stages. Our study indicated the importance of considering both the exposure stages and structure-activity relationship when assessing the eco-toxicological impact of pollutants.

Influence of Bisphenol A on the transport and deposition behaviors of bacteria in quartz sand

The influence of Bisphenol A (BPA) on the transport and deposition behaviors of bacteria in quartz sand was examined in both NaCl (10 and 25 mM) and CaCl₂ solutions (1.2 and 5 mM) by comparing the breakthrough curves and retained profiles of cell with BPA in suspensions versus those without BPA. Gram-negative Escherichia coli and Gram-positive Bacillus subtilis were employed as model cells in the present study. The extended Derjaguin-Landau-Verwey-Overbeek interaction energy calculation revealed that the presence of BPA in cell suspensions led to a lower repulsive interaction between the cells and the quartz sand. This suggests that, theoretically, increased cell deposition on quartz sand would be expected in the presence of BPA. However, under all examined solution conditions, the presence of BPA in cell suspensions increased transport and decreased deposition of bacteria in porous media regardless of cell type, ionic strength, ion valence, the presence or absence of extracellular polymeric substances. We found that competition by BPA through hydrophobicity for deposition sites on the quartz sand surfaces was the sole contributor to the enhanced transport and decreased deposition of bacteria in the presence of BPA.

Solar or UVA-Visible Photocatalytic Ozonation of Water Contaminants

An incipient advanced oxidation process, solar photocatalytic ozonation (SPO), is reviewed in this paper with the aim of clarifying the importance of this process as a more sustainable water technology to remove priority or emerging contaminants from water. The synergism between ozonation and photocatalytic oxidation is well known to increase the oxidation rate of water contaminants, but this has mainly been studied in photocatalytic ozonation systems with lamps of different radiation wavelength, especially of ultraviolet nature (UVC, UVB, UVA). Nowadays, process sustainability is critical in environmental technologies including water treatment and reuse; the application of SPO systems falls into this category, and contributes to saving energy and water. In this review, we summarized works published on photocatalytic ozonation where the radiation source is the Sun or simulated solar light, specifically, lamps emitting radiation to cover the UVA and visible light spectra. The main aspects of the review include photoreactors used and radiation sources applied, synthesis and characterization of catalysts applied, influence of main process variables (ozone, catalyst, and pollutant concentrations, light intensity), type of water, biodegradability and ecotoxicity, mechanism and kinetics, and finally catalyst activity and stability.

Fatty acid metabolism in fish species as a biomarker for environmental monitoring

Pollution by Organic Contaminants (OC) in aquatic environments is a relevant issue at the global scale. Lipids comprised of Fatty Acids (FA) play many important roles in the physiology and life history of fishes. Toxic effects of OC are partly dependent on its bioaccumulation in the lipids of aquatic organisms due its physicochemical properties. Therefore, there is an increasing interest to investigate the gene expression as well as the presence and activity of proteins involved in FA metabolism. The attention on Peroxisome Proliferation Activate Receptors (PPARs) also prevails in fish species exposed to OC and in the transport, biosynthesis and β-oxidation of FA. Several studies have been conducted under controlled conditions to evaluate these biological aspects of fish species exposed to OC, as fibrates, endocrine disrupting compounds, perfluoroalkyl acids, flame retardants, metals and mixtures of organic compounds associated with a polluted area. However, only fibrates, which are agonists of PPARs, induce biological responses suitable to be considered as biomarkers of exposure to these pollutants. According to the documented findings on this topic, it is unlikely that these physiological aspects are suitable to be employed as biomarkers with some noticeable exceptions, which depend on experimental design. This emphasises the need to investigate the responses in fish treated with mixtures of OC and in wild fish species from polluted areas to validate or refute the suitability of these biomarkers for environmental or fish health monitoring.

Bisphenol A induces spermatocyte apoptosis in rare minnow Gobiocypris rarus

Bisphenol A (BPA) is an endocrine disruptor, and could induce germ cells apoptosis in the testis of mammals. But whether it could affect fish in the same mechanism has not' been studied till now. In the present study, to investigate the influence of BPA on testis germ cells in fish, adult male rare minnow Gobiocypris rarus were exposed to 225μgL(-1) (0.99μM) BPA for 1, 3 and 9 weeks. Through TdT-mediated dUTP nick end labeling (TUNEL) and transmission electron microscope (TEM) analysis, we found that the amount of apoptotic spermatocytes significantly increased in a time dependent manner following BPA exposure. Western Blot results showed that the ratio of Bcl2/Bax, the important apoptosis regulators in intrinsic mitochondrial apoptotic pathway, was significantly decreased. qPCR showed that mRNA expression of several genes in mitochondrial apoptotic pathway including bcl2, bax, casp9, cytc and mcl1b were significantly changed following BPA exposure. In addition, mRNA expression of meiosis regulation genes (kpna7 and wee2), and genes involved in both apoptosis and meiosis (birc5, ccna1, and gsa1a) were also affected by BPA. Taken together, the present study demonstrated that BPA could induce spermatocytes apoptosis in rare minnow testis, and the apoptosis was probably under regulation of intrinsic mitochondrial apoptotic pathway. Moreover, the spermatocyte apoptosis was likely initiated by BPA induced meiosis arrest.

Bisphenol Analogues Other Than BPA: Environmental Occurrence, Human Exposure, and Toxicity-A Review

Numerous studies have investigated the environmental occurrence, human exposure, and toxicity of bisphenol A (BPA). Following stringent regulations on the production and usage of BPA, several bisphenol analogues have been produced as a replacement for BPA in various applications. The present review outlines the current state of knowledge on the occurrence of bisphenol analogues (other than BPA) in the environment, consumer products and foodstuffs, human exposure and biomonitoring, and toxicity. Whereas BPA was still the major bisphenol analogue found in most environmental monitoring studies, BPF and BPS were also frequently detected. Elevated concentrations of BPAF, BPF, and BPS (i.e., similar to or greater than that of BPA) have been reported in the abiotic environment and human urine from some regions. Many analogues exhibit endocrine disrupting effects, cytotoxicity, genotoxicity, reproductive toxicity, dioxin-like effects, and neurotoxicity in laboratory studies. BPAF, BPB, BPF, and BPS have been shown to exhibit estrogenic and/or antiandrogenic activities similar to or even greater than that of BPA. Knowledge gaps and research needs have been identified, which include the elucidation of environmental occurrences, persistence, and fate of bisphenol analogues (other than BPA), sources and pathways for human exposure, effects on reproductive systems and the mammary gland, mechanisms of toxicity from coexposure to multiple analogues, metabolic pathways and products, and the impact of metabolic modification on toxicity.

Non-monotonic dose-response effect of bisphenol A on rare minnow Gobiocypris rarus ovarian development

Bisphenol A (BPA) is widely spread in the environment, and can cause various reproductive disrupting effects on different organisms, including fish. Our previous published study showed that BPA has non-monotonic (inverted U-shaped) dose-response effect on rare minnow Gobiocypris rarus ovarian weight at different concentrations. To investigate the potential mechanism, we exposed female rare minnow to 1, 15 and 225 µg L(-1) BPA for 7 days in the present study. The levels of vitellogenin (Vtg), sex hormones, hydrogen peroxide (H2O2), glutathione (GSH) and triglyceride (TG) were measured. RNA-seq of ovary tissues was also performed. Result showed that Vtg, sex hormone and TG levels showed an inverted U-shaped increased response, while H2O2 and GSH levels showed a U-shaped inhibited response. RNA-seq data showed that many genes involved in lipid metabolism, oxidative stress, and proteolysis processes were altered. The change of Vtg, H2O2, GSH and TG levels was possibly related to the altered sex hormone levels. Sex hormone's direct effect, Vtg accumulation, TG accumulation and oxidative stress induced proteolysis may contribute to the change of ovary weight.

Oxidative stress and immunotoxic effects of bisphenol A on the larvae of rare minnow Gobiocypris rarus

Bisphenol A (BPA), a known endocrine disrupting chemical, is ubiquitous in the aquatic environment and can pose risk to the health of aquatic organisms. Studies on immunotoxicity of BPA in aquatic organisms are limited. In this study, rare minnow (Gobiocypris rarus) larvae were exposed to 1, 225 and 1000μg/L BPA for 7 days. Inflammatory effects of BPA exposure were assessed from the increased production of nitric oxide (NO) and reactive oxygen species (ROS), the change of iNOS mRNA and other TLRs-associated immune gene expression. Our findings provide evidences that different concentrations of BPA can induce a toxic response in fish to produce reactive free radicals which can affect the function of T lymphocytes and decrease the transcription levels of cytokine genes. The excess production of H2O2, induced oxidative stress and suppressed TLR4/NF-κB signaling, leading to immunosuppressive effects in fish larvae. The present results suggest that BPA has the potential to induce oxidative stress accompanied by immunosuppression in rare minnow larvae.