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

Thresholds and interactive effects of BPA-gradient and temperature on life history traits of Daphnia magna

Bisphenol A (BPA), a synthetic organic compound widely used in the production of plastics, is recognized as an emerging contaminant because of its toxicity and the potential risks associated with bioaccumulation in organisms. Despite potential environmental hazards, there is a lack of studies examining BPA toxicity mechanisms and its potential impact on various trophic levels, with even fewer exploring whether global stressors such as temperature can affect the toxicity of BPA in organisms. Our aim was to assess the combined impact of BPA and varying temperature regimes on life-history traits in Daphnia magna. Our results revealed a significant impact of BPA on the growth, reproduction, and accumulated moulting of D. magna, with adverse effects primarily associated with the assimilation of BPA in algae rather than the BPA present in the medium, pointing to a trophic transfer mechanism. The interactive effect between BPA and temperature demonstrated a slight stimulatory effect of low BPA level on D. magna growth rate under warming constant conditions, but an inhibitory under warming fluctuating temperatures. Additionally, a BPA threshold was identified, below which growth became temperature-dependent. This study emphasizes the crucial role of considering temperature in predicting how toxins may affect Daphnia within aquatic food webs.

Zooplankton-based adverse outcome pathways: A tool for assessing endocrine disrupting compounds in aquatic environments

Endocrine disrupting compounds (EDCs) pose a significant ecological risk, particularly in aquatic ecosystems. EDCs have become a focal point in ecotoxicology, and their identification and regulation have become a priority. Zooplankton have gained global recognition as bioindicators, benefiting from rigorous standardization and regulatory validation processes. This review aims to provide a comprehensive summary of zooplankton-based adverse outcome pathways (AOPs) with a focus on EDCs as toxicants and the utilisation of freshwater zooplankton as bioindicators in ecotoxicological assessments. This review presents case studies in which zooplankton have been used in the development of AOPs, emphasizing the identification of molecular initiating events (MIEs) and key events (KEs) specific to zooplankton exposed to EDCs. Zooplankton-based AOPs may become an important resource for understanding the intricate processes by which EDCs impair the endocrine system. Furthermore, the data sources, experimental approaches, advantages, and challenges associated with zooplankton-based AOPs are discussed. Zooplankton-based AOPs framework can provide vital tools for consolidating toxicological knowledge into a structured toxicity pathway of EDCs, offering a transformative platform for facilitating enhanced risk assessment and chemical regulation.

Photocatalytic and electrocatalytic degradation of bisphenol A in the presence of graphene/graphene oxide-based nanocatalysts: A review

Bisphenol A (BPA), a widely recognized endocrine disrupting compound, has been discovered in drinking water sources/finished water and domestic wastewater influent/effluent. Numerous studies have shown photocatalytic and electrocatalytic oxidation to be very effective for the removal of BPA, particularly in the addition of graphene/graphene oxide (GO)-based nanocatalysts. Nevertheless, the photocatalytic and electrocatalytic degradation of BPA in aqueous solutions has not been reviewed. Therefore, this review gives a comprehensive understanding of BPA degradation during photo-/electro-catalytic activity in the presence of graphene/GO-based nanocatalysts. Herein, this review evaluated the main photo-/electro-catalytic degradation mechanisms and pathways for BPA removal under various water quality/chemistry conditions (pH, background ions, natural organic matter, promotors, and scavengers), the physicochemical characteristics of various graphene/GO-based nanocatalysts, and various operating conditions (voltage and current). Additionally, the reusability/stability of graphene/GO-based nanocatalysts, hybrid systems combined with ozone/ultrasonic/Fenton oxidation, and prospective research areas are briefly described.

Multigenerational tests on Daphnia spp.: a vision and new perspectives

Multigenerational toxicity testing is a valuable tool for understanding the long-term effects of contaminants on aquatic organisms. This review focuses on the use of multigenerational tests with Daphnia, a widely used model organism in aquatic toxicological studies. The review highlights the importance of studying multiple generations to assess Daphnia spp. reproductive, growth, and physiological responses to various contaminants. We discuss the outcomes of multigenerational tests involving different contaminants, including nanoparticles, pesticides, and pharmaceuticals. The results reveal that multigenerational exposure can lead to transgenerational effects, where the impacts of contaminants are observed in subsequent generations even after the initial exposure has ceased. These transgenerational effects often manifest as reproduction, growth, and development alterations. Furthermore, we emphasize the need for standardized protocols in multigenerational testing to ensure comparability and reproducibility of results across studies. We also discuss the implications of multigenerational testing for ecological risk assessment, as it provides a more realistic representation of the long-term effects of contaminants on populations and ecosystems. Overall, this review highlights the significance of multigenerational tests with Daphnia in advancing our understanding of the ecological impacts of contaminants. Such tests provide valuable insights into the potential risks associated with long-term exposure to pollutants and contribute to the development of effective mitigation strategies for aquatic ecosystems.

Risk assessment of bisphenol analogues towards mortality, heart rate and stress-mediated gene expression in cladocerans Moina micrura

Bisphenol A (BPA) is a well-known endocrine-disrupting compound that causes several toxic effects on human and aquatic organisms. The restriction of BPA in several applications has increased the substituted toxic chemicals such as bisphenol F (BPF) and bisphenol S (BPS). A native tropical freshwater cladoceran, Moina micrura, was used as a bioindicator to assess the adverse effects of bisphenol analogues at molecular, organ, individual and population levels. Bisphenol analogues significantly upregulated the expressions of stress-related genes, which are the haemoglobin and glutathione S-transferase genes, but the sex determination genes such as doublesex and juvenile hormone analogue genes were not significantly different. The results show that bisphenol analogues affect the heart rate and mortality rate of M. micrura. The 48-h lethal concentration (LC₅₀) values based on acute toxicity for BPA, BPF and BPS were 611.6 µg L^-1, 632.0 µg L^-1 and 819.1 µg L^-1, respectively. The order of toxicity based on the LC₅₀ and predictive non-effect concentration values were as follows: BPA > BPF > BPS. Furthermore, the incorporated method combining the responses throughout the organisation levels can comprehensively interpret the toxic effects of bisphenol analogues, thus providing further understanding of the toxicity mechanisms. Moreover, the output of this study produces a comprehensive ecotoxicity assessment, which provides insights for the legislators regarding exposure management and mitigation of bisphenol analogues in riverine ecosystems.

Assessment of single and combined effects of bisphenol-A and its analogue bisphenol-S on biochemical and histopathological responses of sea cucumber Holothuria poli

Bisphenols (BPs) are among emerging pollutants that have been frequently detected in different compartments of marine ecosystems and elicited great concern due to their potential toxicity to marine organisms. This work aimed to investigate the toxicity of bisphenol A (BPA) and bisphenol S (BPS) on oxidative stress markers, neurotoxicity and histopathological alterations in sea cucumbers (Holothuria poli). The results showed that exposure to 200 μg/L of BPA and BPS produced oxidative stress, neurotoxicity in the digestive tract and respiratory tree, and several types of histopathological lesions in tissues of the respiratory tree of the sea cucumber, posing a health hazard to this aquatic organism. In addition, BPA has greater effects than BPS on the generation of oxidative stress marked by the inductions of catalase (CAT), glutathione S-transferase (GST) and malondialdehyde (MDA) levels and neurotoxicity shown by the decrease in acetylcholinesterase activity (AChE). The respiratory tree of sea cucumbers might be an appropriate tissue for assessing CAT, MDA and AChE activity levels, which are reliable biomarkers that may be useful in marine biomonitoring studies. Evaluation of histopathological lesions of the respiratory tree suggests that BPA and BPS and their mixture cause various tissue alterations that may be associated with oxidative stress damage and neurotoxicity. In conclusion, this study showed that oxidative stress (CAT and MDA) and neurotoxicity (AChE) markers, as well as respiratory tree lesions, are sensitive biomarkers for the assessment of BPA and BPS toxicity in sea cucumbers.

Life history traits of low-toxicity alternative bisphenol S on Daphnia magna with short breeding cycles: A multigenerational study

Due to relatively lower toxicity, bisphenol S (BPS) has become an alternative to previously used bisphenol A. Nevertheless, the occurrence of BPS and its ecological impact have recently attracted increasing attentions because the toxicology effect of BPS with life cycle or multigenerational exposure on aquatic organisms remains questionable. Herein, Daphnia magna (D. magna) multigenerational bioassays spanning four generations (F0-F3) and single-generation recovery (F1 and F3) in clean water were used to investigate the ecotoxicology of variable chronic BPS exposure. For both assays, four kinds of life-history traits (i.e., survival, reproduction, growth and ecological behavior) were examined for each generation. After an 18-day exposure under concentration of 200 μg/L, the survival rate of D. magna was less than 15 % for the F2 generation, whereas all died for the F3 generation. With continuous exposure of four generations of D. magna at environmentally relevant concentrations of BPS (2 μg/L), inhibition of growth and development, prolonged sexual maturity, decreased offspring production and decreased swimming activity were observed for the F3 generation. In particular, it is difficult for D. magna to return to its normal level through a single-generation recovery in clean water in terms of reproductive function, ecological behavior and population health. Hence, multi-generational exposure to low concentrations of BPS can have adverse effects on population health of aquatic organisms with short breeding cycles, highlighting the necessity to assess the ecotoxicology of chronic BPS exposure for public health.

Acute and Chronic Toxicity of Binary Mixtures of Bisphenol A and Heavy Metals

Bisphenol A (BPA) and heavy metals are widespread contaminants in the environment. However, the combined toxicities of these contaminants are still unknown. In this study, the bioluminescent bacteria Vibrio qinghaiensis Q67 was used to detect the single and combined toxicities of BPA and heavy metals, then the joint effects of these contaminants were evaluated. The results show that chronic toxicities of chromium (Cr), cadmium (Cd), lead (Pb), arsenic (As), mercury (Hg), nickel (Ni), and BPA were time−dependent; in fact, the acute toxicities of these contaminants were stronger than the chronic toxicities. Furthermore, the combined toxicities of BPA and heavy metals displayed BPA + Hg > BPA + Cr > BPA + As > BPA + Ni > BPA + Pb > BPA + Cd in the acute test and BPA + Hg > BPA + Cd > BPA + As > BPA + Cd in the chronic test, which suggested that the combined toxicity of BPA and Hg was stronger than that of other mixtures in acute as well as chronic tests. Additionally, both CA and IA models underestimated the toxicities of mixtures at low concentrations but overestimated them at high concentrations, which indicates that CA and IA models were not suitable to predict the toxicities of mixtures of BPA and heavy metals. Moreover, the joint effects of BPA and heavy metals mainly showed antagonism and additive in the context of acute exposure but synergism and additive in the context of chronic exposure. Indeed, the difference in the joint effects on acute and chronic exposure can be explained by the possibility that mixtures inhibited cell growth and luminescence in chronic cultivation. The chronic toxicity of the mixture should be considered if the mixture results in the inhibition of the growth of cells.

Occurrence, spatial distribution, and main source identification of ten bisphenol analogues in the dry season of the Pearl River, South China

Bisphenol analogues (BPs) including bisphenol a (BPA) have been broadly utilized as industrial feedstocks and unavoidably discharged into water bodies. However, there is little published data on the occurrence, distribution, and environmental risks of other BPs in surface water. In this study, ten BPs besides BPA were analyzed in surface water from the Pearl River, South China. Among these detected BPs, BPA, bisphenol F (BPF), bisphenol AF (BPAF), and bisphenol S (BPS) were the most frequently detected compounds. The median concentrations of the measured BPs were ranked in the order of BPA (34.9 ng/L) > BPS (24.8 ng/L) > BPAF (10.1 ng/L) > bisphenol F (BPF) (9.0 ng/L) > bisphenol B (BPB) (7.6 ng/L) > bisphenol C (BPC) (1.2 ng/L). Among them, BPA and BPS were predominant BPs, contributing 68% of the total ten BPs in surface water of the Pearl River. These results demonstrated that BPA and BPS were the most extensively utilized and manufactured BPs in this region. The source analysis of BPs suggested that the BPs may be originated from domestic wastewater, wastewater treatment plant (WWTP) effluent, and the leaching of microplastic in surface water of the Pearl River. The calculated BP-derived estrogenic activity exhibited low to medium risks in surface water, but their combined estrogenic effects with other endocrine disrupting compounds should not be ignored.

Sublethal effects of DBE-DBCH diastereomers on physiology, behavior, and gene expression of Daphnia magna

1,2-dibromo-4-(1,2-dibromoethyl)-cyclohexane (DBE-DBCH) is a brominated flame retardant used in commercial and industrial applications. The use of DBE-DBCH containing products has resulted in an increased release into the environment. However, limited information is available on the long-term effects of DBE-DBCH and its effects in aquatic invertebrates. Thus, the present study was aimed at determining how DBE-DBCH diastereomers (αβ and γδ) affects aquatic invertebrates using Daphnia magna as a model organism. Survival, reproduction, feeding, swimming behavior and toxicogenomic responses to environmental relevant concentrations of DBE-DBCH were analyzed. Chronic exposure to DBE-DBCH resulted in decreased lifespan, and reduced fecundity. Expression of genes involved in reproductive processes, vtg1 and jhe, were also inhibited. DBE-DBCH also induced hypoxia by inhibiting the transcription of genes involved in heme biosynthesis and oxygen transport. Furthermore, DBE-DBCH also inhibited feeding resulting in emptiness of the alimentary canal. Increased expression of the stress response biomarkers was observed following DBE-DBCH exposure. In addition, DBE-DBCH diastereomers also altered the swimming behavior of Daphnia magna. The present study demonstrates that DBE-DBCH cause multiple deleterious effects on Daphnia magna, including effects on reproduction and hormonal systems. These endocrine disrupting effects are in agreement with effects observed on vertebrates. Furthermore, as is the case in vertebrates, DBE-DBCH γδ exerted stronger effects than DBE-DBCH αβ on Daphnia magna. This indicate that DBE-DBCH γδ has properties making it more toxic to all so far studied animals than DBE-DBCH αβ.

The risk and impact of organophosphate esters on the development of female-specific cancers: Comparative analysis of patients with benign and malignant tumors

Environmental pollution has become a concern for public health. As endocrine disruptors, organophosphate esters (OPEs) causes many diseases via human exposure. However, there is limited research on the risk of OPE exposure to female-specific cancers. Blood measurements are biomarkers for chemical exposures by their definition. Thus, in the present study, 11 OPEs were analyzed in the plasma of patients with 4 female-specific tumors. 2-Ethylhexyl diphenyl phosphate (EHDPP) was detected at the highest levels in all groups. The Spearman correlation test results showed significantly positive correlations between some OPEs in each group, which indicated that those OPEs had similar sources and/or behaved similarly in the patients of each group. However, compared with different patient groups, obvious differences in the correlation results were noted, implying the differences in the metabolism of OPEs between different groups. The results of the correlation analysis showed that EHDPP concentration was associated with the risk of breast cancer (p < 0.05), while tri-n-butyl phosphate (TNBP), tris (methylphenyl) phosphate (TMPP), triphenyl phosphate (TPHP), and EHDPP concentrations were associated with the risk of cervical cancer (p < 0.05 or p < 0.01). These findings indicated that OPEs were associated with the risk of breast and cervical cancer.

Distribution and mass loads of xenoestrogens bisphenol a, 4-nonylphenol, and 4-tert-octylphenol in rainfall runoff from highly urbanized regions: A comparison with point sources of wastewater

This study pays a special attention to three phenolic endocrine disrupting compounds (EDCs), - bisphenol A (BPA), 4-nonylphenol (4-NP), and 4-tert-octylphenol (4-t-OP) - that are present in urban environments, resultant of several anthropogenic activities that can be also carried through rainfall runoff. We investigated the distributions of BPA, 4-NP, and 4-t-OP in Pearl River basin and estimated the mass loads in rainfall runoff, wastewater treatment plant (WWTP) effluents, and industrial wastewater from urbanized Huizhou and Dongguan regions. These three phenolic EDCs were detected frequently in tributaries and mainstream of Dongjiang River with the maximum 4-NP concentrations of 14,540 ng/L in surface waters and 3088 ng/g in sediments. BPA showed high concentrations in rainfall runoff samples with maximum concentrations of 5873 and 2397 ng/L in Huizhou and Dongguan regions, respectively, while concentrations for 4-NP and 4-t-OP were detected at tens to hundreds of nanograms per liter. Mass loads of phenolic EDCs from rainfall runoff were 3-62 times higher than those of WWTP effluents, suggesting rainfall runoff is an important source of phenolic EDCs into receiving waters. Sources and tributaries showed median to high estrogenic risks, while low to median risks were found in mainstream, implying the source control should be focused.

Occurrence, mass loads and risks of bisphenol analogues in the Pearl River Delta region, South China: Urban rainfall runoff as a potential source for receiving rivers

Bisphenol (BP) analogues are widely used as industrial materials and various product additives and are inevitably released into environment. However, knowledge on the sources of different BPs, especially those from urban rainfall runoff to the receiving rivers is very limited. In this study, 15 BPs were determined in surface water, sediments, wastewater treatment plant (WWTP) and rainfall runoff samples in the Pearl River region, South China. Eleven BPs were detected in surface water and sediments of the Pearl Rivers. BPA was the dominant compound up to 2080 ng/L in surface and 1970 ng/g in sediments, followed by BPF, BPS, BPTMC and BPAF. In WWTPs, 10, 9 and 8 BPs were detected in influents, effluents and excess sludges, respectively, with total BPs (ΣBPs) concentrations in effluents still at thousands ng/L, suggesting incompletely removal of BPs. Five BPs were detected in urban rainfall runoff samples, with the ΣBPs concentrations up to 7740 ng/L. Mass loads of ΣBPs from the rainfall runoff (5800 kg/y) were almost equivalent to the source from WWTPs (7370 kg/y) in the region, implying that the urban rainfall runoff was a potential source for BPs into the receiving river. The calculated estrogenic activity contributed by BPs showed low to median risks in sources and receiving rivers. But BPs are always as mixtures with other potential endocrine disrupting chemicals (EDCs) which probably pose high estrogenic activity risks. Hence, effective measures should be taken to decrease the input of EDCs from sources to receiving rivers.

Bisphenol P activates hormonal genes and introduces developmental outcomes in Chironomus tentans

The endocrine disrupting properties of bisphenol A (BPA) discharged to the environment have been newly identified by the European Chemicals Agency, increasing the need to assess the environmental endocrine disrupting potentials of its alternatives with which it shares close structural features. However, few investigations of the environmental endocrine disrupting functions of BPA analogs have been conducted to date. In this study, the endocrine disrupting effects of a BPA analog of bisphenol P (BPP) were investigated in the nonbiting midge (Chironomus tentans), a model organism in ecotoxicology. An initial ex vivo test using salivary gland cells explanted from the larvae and a subsequent in vivo test using embryos and larvae revealed the upregulatory effects of BPP on ecdysone receptor genes encoding the ecdysone receptor (EcR) and the early responsive gene E74, with a similar temporal pattern of gene activation. Partial life cycle and full life cycle toxicity tests demonstrated BPP altered embryo hatching, larval emergence, and adult sex ratio at concentrations close to the effective concentrations for hormonal genetic endpoints in embryos and larvae after 48 h of exposure. Although embryos appeared to be more sensitive to BPP than the fourth instar larvae, the impact on neither life stage seemed enough to estimate the developmental impairment of the insects. These results demonstrate the ecdysone pathway is a target of BPP, and that long-term exposure could cause apical effects on the development of C. tentans. The endocrine disrupting effects towards aquatic organisms, as well as the high persistence and bioconcentration potential, indicate an urgent need to assess the environmental risks associated with BPP.

Selective Amino Acid-Only in Vivo NMR: A Powerful Tool To Follow Stress Processes

In vivo NMR of small 13C-enriched aquatic organisms is developing as a powerful tool to detect and explain toxic stress at the biochemical level. Amino acids are a very important category of metabolites for stress detection as they are involved in the vast majority of stress response pathways. As such, they are a useful proxy for stress detection in general, which could then be a trigger for more in-depth analysis of the metabolome. 1H-13C heteronuclear single quantum coherence (HSQC) is commonly used to provide additional spectral dispersion in vivo and permit metabolite assignment. While some amino acids can be assigned from HSQC, spectral overlap makes monitoring them in vivo challenging. Here, an experiment typically used to study protein structures is adapted for the selective detection of amino acids inside living Daphnia magna (water fleas). All 20 common amino acids can be selectively detected in both extracts and in vivo. By monitoring bisphenol-A exposure, the in vivo amino acid-only approach identified larger fluxes in a greater number of amino acids when compared to published works using extracts from whole organism homogenates. This suggests that amino acid-only NMR of living organisms may be a very sensitive tool in the detection of stress in vivo and is highly complementary to more traditional metabolomics-based methods. The ability of selective NMR experiments to help researchers to "look inside" living organisms and only detect specific molecules of interest is quite profound and paves the way for the future development of additional targeted experiments for in vivo research and monitoring.

Food up-take and reproduction performance of Daphnia magna under the exposure of Bisphenols

Because the application of Bisphenol A (BPA) was restricted, many substitutes, such as Bisphenol F (BPF) and Bisphenol S (BPS), were developed as BPA substitutes. Therefore, environmental impacts of BPA and its substitutes on aquatic organisms should be concerned, especially their combined toxicity. In this study, the impacts of BPA, BPF, BPS and their mixture on the feeding behavior, reproduction and physiological function of daphnids were synthetically evaluated, involving the duration and mode of exposure. In short-term exposure tests, feeding rates of D. magna decreased after exposure to BPA, BPF, BPS and their mixture, while the inhibition reversed into stimulation in the recovery period. It may benefit from overcompensation of D. magna. In long-term exposure tests, the inhibition effect on the reproduction and growth of the exposed D. magna was difficult to recover, and only some experimental groups have a certain recovery. In conclusion, environmental risk of BPA, BPF, BPS and their mixture on the behavior of D. magna increased with prolonged exposure time. Moreover, relative activities of trypsin, amylase (AMS), acetylcholinesterase (AChE), carbonic anhydrase (CA), glutathione peroxidase (GPx) and super oxidase dimutase (SOD) of the exposed daphnids decreased in most treatment groups, indicating the disorder of digestive, nervous and antioxidative system of D. magna. Interestingly, inhibition of enzymes activities decreased with the increase of the exposure time, which implied the tolerance may be occurred.