Combined toxicities of cadmium and five agrochemicals to the larval zebrafish (Danio rerio)

Brodeur J.C., Damonte M.J., Rojas D.E., Cristos D., Vargas C., Poliserpi M.B., Andriulo A.E.

Contamination with current-use pesticides is frequently mentioned as a key factor in global amphibian declines although a limited number of studies have examined the mixture of pesticides accumulated by free-living frogs. This study examined the presence of 46 different pesticide residues in the muscle and kidney tissues of two frog species living in close association with row crops in the Pampa region of Argentina: The terrestrial Leptodactylus latinasus and the semi-aquatic Leptodactylus latrans. A total of 20 different pesticides were identified in frog tissues; chlorpyrifos-methyl, pirimiphos-methyl and acetochlor being the most frequently detected molecules. Overall, one or more pesticide residues (up to 12 in a single frog) were detected in 40-57 % of L. latrans. L. latinasus was found to present more pesticide detections than L. latrans. Interestingly, frog sampled in a natural reserve where no pesticides are applied presented an equivalent frequency of detections as frogs living near a crop. In L. latrans, the calculation of a pesticide toxicity index (PTI) permitted to highlight the existence of a strong positive correlation between PTI and liver GSH contents of females whereas, in males, PTI was negatively correlated with the perimeter of testicular seminiferous tubules. Males also presented near significant negative correlations between PTI and both body condition and the scaled fat index. These results indicate that frogs inhabiting agricultural regions are exposed to a complex and diffuse contamination by pesticide mixtures which is likely responsible for a number of biological effects that may be relevant at the population level.

Yadav A., Bagotia N., Sharma A.K., Kumar S.

The rapid growth of population and industrialization results in pollution of freshwater sources which leads to the water stress conditions on the world in future. Adsorption is a low cost and popular technique for the removal of contaminants from water bodies. Most of the reports till date are on removal of a single component from aqueous solutions using this technique, but the real-world effluent contains multiple contaminants such as dyes, heavy metals, pesticides, antibiotics and many more. Therefore, a study on simultaneous removal of contaminants is highly needed to obtain a suitable adsorbent that can be used commercially. This critical review provides a detailed study on the removal of contaminants in the presence of other contaminant/s i.e., from a multi-component system (MCS). The different possible interaction mechanisms in MCS like synergism, antagonism and non-interaction are discussed. The MCS containing the mixture of conventional contaminants such as heavy metals and dyes, and other emerging contaminants such as antibiotics, organic contaminants, pesticides and personal care products are explained in depth. This review article will be helpful for researchers working in the field of simultaneous removal of contaminants from MCSs for wastewater remediation.

Wang M., Chen Z., Song W., Hong D., Huang L., Li Y.

The rapid industrial development has led to serious cadmium (Cd) pollution. Cd is a toxic heavy metal placing severe health threat to human. Cd can enter the body through the atmosphere, water, soil and food, and has a long half-life (10–30 years), it largely accumulates in kidneys, liver, bone and other organs and causes irreversible damage to the target organs. Cd pollution has also further caused certain carcinogenic and non-carcinogenic health risk. This study summarizes the current situation of Cd pollution, the toxicity of specific target organs, carcinogenic risk and non-carcinogenic risk in the general population, as well as dietary supplements to prevent and mitigate Cd toxication, which aims to focus on the adverse effects of Cd to human from both individual and population perspectives, hoping that not only the health risk of Cd poisoning can be reduced, but also the accurate prevention and control of Cd poisoning can be achieved in the future.

Cao Y., Ibáñez Navarro A., Perrella L., Cedergreen N.

Hydrolysis catalyzed by general esterases (GEs) is the most efficient route for hydrolyzation of pyrethroid insecticides. Organophosphate (OP) and carbamate (CB) insecticides are known to inhibit GEs in addition to acetylcholinesterase (AChE), which is their main target. We hypothesize that synergies can be induced by OPs and CBs when mixed with pyrethroids, due to their inhibition of GE-dependent detoxification of pyrethroids. To test this hypothesis, we conducted mixture toxicity experiments with Daphnia magna using α-cypermethrin (α-cyp) in combination with the noninsecticidal OP tetraisopropyl pyrophosphoramide (iso-OMPA) and five AChE inhibitors diazinon, chlorpyrifos, chlorfenviphos, parathion, and aldicarb. In addition, the in vivo GE activity inhibition was measured for all compounds. Up to 10-fold synergy was found between α-cyp and iso-OMPA, and the degree of synergy correlated linearly with the inhibition of the GE activity. No synergy, however, was found in any of the insecticide mixtures nor was the GE activity inhibited within the nonlethal concentration range tested. It was concluded that the effect of the insecticides on AChE occurred at lower concentrations than their effect on GEs, making the daphnids become immobilized before any synergistic effects on mortality could be observed. The implications of the findings are discussed from a risk assessment perspective.

Abe F.R., Accoroni K.A., Gravato C., de Oliveira D.P.

Fish embryo toxicity (FET) test using zebrafish (Danio rerio) has been established as an alternative assay to animal experimentation. The FET assay enables the assessment of multiple morphological endpoints during the development of zebrafish early life stages, showing high impact to the field of ecotoxicology on risk assessment of chemicals and pollutants. Moreover, it is also applied to screening drug-induced toxicity and human diseases, due to the high genetic and physiological orthology between zebrafish and humans. Here, we describe FET test, with all steps and several adaptations involved in the methodological procedures. To demonstrate the efficiency of this method, results using the reference substance 3,4-dichloroaniline (DCA) were included to demonstrate sublethal and teratogenic malformations on zebrafish embryos. Thus, there is a strong tendency for using FET tests as a replacement strategy of traditional tests in toxicology and ecotoxicology.

Martin O., Scholze M., Ermler S., McPhie J., Bopp S.K., Kienzler A., Parissis N., Kortenkamp A.

• Systematic review and quantitative reappraisal of 10 years’ of experimental mixture studies. • Inventory of 1220 mixture experiments subjected to subgroup analyses. • Quantitative reappraisal of 557 claimed deviations from expected additivity, classed by their authors as synergisms, antagonism, interactions or potentiations. • Few claims of synergistic or antagonistic effects exceeded the boundaries of acceptable between-study variability. • Results confirm the utility of default application of the dose (concentration) addition concept for predictive assessments of simultaneous exposures to multiple chemicals. • Application of dose addition must be complemented by an awareness of the synergistic potential of specific classes of chemicals. Several reviews of synergisms and antagonisms in chemical mixtures have concluded that synergisms are relatively rare. However, these reviews focused on mixtures composed of specific groups of chemicals, such as pesticides or metals and on toxicity endpoints mostly relevant to ecotoxicology. Doubts remain whether these findings can be generalised. A systematic review not restricted to specific chemical mixtures and including mammalian and human toxicity endpoints is missing. We conducted a systematic review and quantitative reappraisal of 10 years’ of experimental mixture studies to investigate the frequency and reliability of evaluations of mixture effects as synergistic or antagonistic. Unlike previous reviews, we did not limit our efforts to certain groups of chemicals or specific toxicity outcomes and covered mixture studies relevant to ecotoxicology and human/mammalian toxicology published between 2007 and 2017. We undertook searches for peer-reviewed articles in PubMed, Web of Science, Scopus, GreenFile, ScienceDirect and Toxline and included studies of controlled exposures of environmental chemical pollutants, defined as unintentional exposures leading to unintended effects. Studies with viruses, prions or therapeutic agents were excluded, as were records with missing details on chemicals’ identities, toxicities, doses, or concentrations. To examine the internal validity of studies we developed a risk-of-bias tool tailored to mixture toxicology. For a subset of 388 entries that claimed synergisms or antagonisms, we conducted a quantitative reappraisal of authors’ evaluations by deriving ratios of predicted and observed effective mixture doses (concentrations). Our searches produced an inventory of 1220 mixture experiments which we subjected to subgroup analyses. Approximately two thirds of studies did not incorporate more than 2 components. Most experiments relied on low-cost assays with readily quantifiable endpoints. Important toxicity outcomes of relevance for human risk assessment (e.g. carcinogenicity, genotoxicity, reproductive toxicity, immunotoxicity, neurotoxicity) were rarely addressed. The proportion of studies that declared additivity, synergism or antagonisms was approximately equal (one quarter each); the remaining quarter arrived at different evaluations. About half of the 1220 entries were rated as “definitely” or “probably” low risk of bias. Strikingly, relatively few claims of synergistic or antagonistic effects stood up to scrutiny in terms of deviations from expected additivity that exceed the boundaries of acceptable between-study variability. In most cases, the observed mixture doses were not more than two-fold higher or lower than the predicted additive doses. Twenty percent of the entries (N = 78) reported synergisms in excess of that degree of deviation. Our efforts of pinpointing specific factors that predispose to synergistic interactions confirmed previous concerns about the synergistic potential of combinations of triazine, azole and pyrethroid pesticides at environmentally relevant doses. New evidence of synergisms with endocrine disrupting chemicals and metal compounds such as chromium (VI) and nickel in combination with cadmium has emerged. These specific cases of synergisms apart, our results confirm the utility of default application of the dose (concentration) addition concept for predictive assessments of simultaneous exposures to multiple chemicals. However, this strategy must be complemented by an awareness of the synergistic potential of specific classes of chemicals. Our conclusions only apply to the chemical space captured in published mixture studies which is biased towards relatively well-researched chemicals. The final protocol was published on the open-access repository Zenodo and attributed the following digital object identifier, doi: https://doi.org//10.5281/zenodo.1319759 ( https://zenodo.org/record/1319759#.XXIzdy7dsqM ).

Xie D., Chen C., Li C., Wang Q.

To understand the influence of Cd on atrazine (ATZ) degradation in aqueous solution, the degradation of different initial levels of ATZ (0.1, 0.5, 1.0, and 2.0 mg·L−1) was investigated in the presence and absence of Cd2+ in a 20-day laboratory experiment. It was found that Cd2+ caused a significant decrease in ATZ degradation and increased its half-life from 17–34 days to 30–57 days (p < 0.0001). Regarding the three most common metabolites of ATZ, deethylatrazine (DEA) and deisopropylatrazine (DIA) were detected in water earlier than hydroxyatrazine (HYA). The DEA content was several times higher than the DIA and HYA contents, regardless of the presence or absence of Cd2+. In the presence of Cd2+, the DIA content was significantly lower and the HYA content was significantly higher. Furthermore, Cd2+ had a dose-dependent effect on HYA formation. Our results indicated that the coexistence of Cd2+ and ATZ resulted in greater herbicide persistence, thereby possibly increasing the risk of environmental contamination. DEA was still the predominant ATZ degradation product detected in water under the combined pollution, which was similar to the ATZ tendency.

Zhang R., Wang M., Chen X., Yang C., Wu L.

The effects of microplastics (MPs) on organisms have drawn a worldwide attention in the recent years. In this study, zebrafish embryos were employed to assess the combined effects of MPs and cadmium (Cd) on the aquatic organisms. Lethal and sublethal effects were recorded at 8, 24, 32, 48 and 96 hpe (hour post exposure, hpe). The exposure under a series concentration of MPs and/or an environmental level Cd has the negative impacts on survival and heart rate (HR). And there was a positive correlation between MPs concentration and lethal and sublethal toxicity under combined exposure. The physiological parameters showed that the mixture of two stressors had the antagonistic toxicity under low concentration of MPs (0.05, 0.1 mg/L) while the synergistic sublethal toxicity under high levels of MPs (1, 5, 10 mg/L) on zebrafish embryos. Both the scanning electron micrographs (SEM) and fluorescence microscope photos suggested an electrostatic interaction and weak physical forces generated between MPs and chorion membrane. It is inferred that the 10 μm MPs could induce the protective effect of chorion membrane and cause complex toxicities with Cd. But when it involved with other pollutants, the toxic effects and mechanism are still waiting to be figured out.

Schuwirth N.

Surface water quality management requires foresighted decision making regarding long-term investments. It should consider multiple objectives (e.g. related to different pollutants and costs), integrate multiple sources of pollution (point and diffuse sources), and external conditions that change over time (climate, population and land-use changes). Multi-attribute value theory can support such decisions, especially the development of an assessment method. Integrated surface water quality assessment methods including micropollutants are currently lacking or in development in many countries. Important steps for the development of such an immission oriented and integrated surface water quality assessment method are discussed in this paper and exemplified for organic micropollutants. The proposed assessment method goes beyond simple pass-fail criteria for single substances. It provides a continuous assessment on a scale from zero to one based on five color-coded water quality classes and suggestions for the visualization of assessment results. It takes into account the toxicity of the micropollutants and their mixture to aquatic organisms by comparing measured concentrations to environmental quality standards (EQS). The focus of this paper is on aggregation over multiple substances and time. Advantages and disadvantages of different aggregation methods are discussed as well as their implications for practice. The consequences of different aggregation methods are illustrated with didactical examples and by an application of the proposed water quality assessment method to pesticide monitoring data from Switzerland. Recommendations are provided that account for the purpose of the assessment. Furthermore, the paper illustrates how the proposed method can facilitate dealing with uncertainty and a transparent communication of monitoring results to support water quality management decisions.

de Abreu M.S., Genario R., Giacomini A.C., Demin K.A., Lakstygal A.M., Amstislavskaya T.G., Fontana B.D., Parker M.O., Kalueff A.V.

Neurodevelopmental disorders (NDDs) caused by aberrant brain growth and development are life-long, debilitating illnesses that markedly impair the quality of life. Animal models are a valuable tool for studying NDD pathobiology and therapies. Mounting evidence suggests the zebrafish (Danio rerio) as a useful model organism to study NDDs, possessing both high physiological homology to humans and sensitivity to pharmacological and genetic manipulations. Here, we summarize experimental models of NDDs in zebrafish and highlight the growing translational significance of zebrafish NDD-related phenotypes. We also emphasize the need in further development of zebrafish models of NDDs to improve our understanding of their pathogenesis and therapeutic treatments.

Tao M., Bian Z., Zhang J., Wang T., Shen H.

Organophosphorus pesticide (OPP) pollutants in the environment pose toxicity risks to living organisms, and the possible toxicity mechanism needs to be further clarified.

Jia Z., Zhang Y., Huang Q., Jones A.K., Han Z., Zhao C.

• Broflanilide shows low toxicity to zebrafish ( Danio rerio ). • Both CYP450 and GST significantly contribute to the detoxification of broflanilide. • Long-term exposure to broflanilide could lead high bioconcentration risks in D. rerio . Broflanilide, a novel meta-diamide insecticide, shows high insecticidal activity against agricultural pests and is scheduled to be launched onto the market in 2020. However, little information about its potential toxicological effects on fish has been reported. In this study, broflanilide showed low toxicity to the zebrafish, Danio rerio , with LC 50 > 10 mg L −1 at 96 h and also did not inhibit GABA-induced currents of the heteromeric Drα1β2Sγ2 GABA receptor. Broflanilide showed medium bioconcentration level with a bioconcentration factor at steady state ( BCF ss ) of 10.02 and 69.40 in D. rerio at 2.00 mg L −1 and 0.20 mg L −1 , respectively. In the elimination process, the concentration of broflanilide rapidly decreased within two days and slowly dropped below the limit of quantification after ten days. In the 2.00 mg L -1 broflanilide treatment, CYP450 activity was significantly increased up to 3.11-fold during eight days. Glutathione- S - transferase (GST) activity significantly increased by 91.44 % within four days. In conclusion, the acute toxicity of broflanilide was low, but it might induce chronic toxicity, affecting metabolism. To our knowledge, this is the first report of the toxicological effects of broflanilide on an aquatic organism, which has the potential to guide the use of broflanilide in the field.

Gonçalves Í.F., Souza T.M., Vieira L.R., Marchi F.C., Nascimento A.P., Farias D.F.

The use of zebrafish (Danio rerio) has arisen as a promising biological platform for toxicity testing of pesticides such as herbicides, insecticides, and fungicides. Therefore, it is relevant to assess the use of zebrafish in models of exposure to investigate the diversity of pesticide-associated toxicity endpoints which have been reported. Thus, this review aimed to assess the recent literature on the use of zebrafish in pesticide toxicity studies to capture data on the types of pesticide used, classes of pesticides, and zebrafish life stages associated with toxicity endpoints and phenotypic observations. A total of 352 articles published between September 2012 and May 2019 were curated. The results show an increased trend in the use of zebrafish for testing the toxicity of pesticides, with a great diversity of pesticides (203) and chemical classes (58) with different applications (41) being used. Furthermore, experimental outcomes could be clustered in 13 toxicity endpoints, mainly developmental toxicity, oxidative stress, and neurotoxicity. Organophosphorus, pyrethroid, azole, and triazine were the most studied classes of pesticides and associated with various toxicity endpoints. Studies frequently opted for early life stages (embryos and larvae). Although there is an evident lack of standardization of nomenclatures and phenotypic alterations, the information gathered here highlights associations between (classes of) pesticides and endpoints, which can be used to relate mechanisms of action specific to certain classes of chemicals.

Yeh G., Hoang H., Lin C., Bui X., Tran H., Shern C., Vu C.

One of the most industrially affected rivers in Taiwan, the Houjing River, was studied in this research. The water and sediment samples were collected at five locations to measure the concentration of eight metals (As, Cd, Cr, Cu, Hg, Pb, Ni, and Zn). In order to assess the heavy metal contamination and its adverse biological effect, the heavy metal pollution index (HPI), the degree of contamination index (DC), the contamination factor (CF), the index of geo-accumulation (Igeo), and hazard quotients (HQs) were employed. The results showed that the Houjing River’s water and sediment were contaminated with heavy metals. The annually averaged values of HPI (128.3) and DC (21.3) indicate that the water is unsafe for potable use and the sediment contamination level is at considerable degree of contamination. CF and Igeo calculation show that Zn, Cu, and Cd are the three main metals contributing to heavy metal contamination in sediment. Evaluation of adverse biological effects suggests that Zn, Cu, and Ni are the major metals that cause adverse effects on organisms. This study provides an overview of the synergistic heavy metal contamination degree of the Houjing River and its adverse biological effects, which should be a reliable reference for future contamination control and management plans.

Park S., Lee J., Park H., Song G., Lim W.

Bifenthrin is a synthesized pyrethroid insecticide which is frequently used in the farmland to eradicate insects. Bifenthrin mainly disrupts sodium ion channel inducing neurotoxicity in the target insects. It also exerts toxic effects such as hormone dysregulation, hepatotoxicity and immunotoxicity in other vertebrates. However, there is no evidence of the acute-toxicity associated embryogenesis and organogenesis of bifenthrin in zebrafish. Here we first demonstrated that bifenthrin induced acute-toxicity accompanying inflammatory response and physiological degradations resulting in loss of embryogenesis and vascular development in zebrafish embryos. We found that bifenthrin increased intestinal ROS accumulation and the inflammatory genes including tnfa, il6, il8 and ptgs2b, thereby increasing embryo mortality. Moreover, bifenthrin disrupted angiogenesis by down-regulation of VEGF receptors in embryos. Not only in the zebrafish, bifenthrin also decreased cell viability and hampered vascular formation of HUVECs. Collectively, bifenthrin induced developmental toxicity, inflammatory cell death and anti-angiogenesis during embryogenesis.

Reda R.M., Zaki E.M., A. A. Aioub A., Metwally M.M., Yassin A.M., Mahsoub F.

Abstract The aquaculture sector is facing environmental issues because of rising chemical pollution of aquatic systems, which may be caused by man-made or natural causes. The combined action of these mixtures can produce an effect that is either severalfold higher or severalfold lower than the overall toxicity of the individual components. The objective of this study is to evaluate the impact of three individual toxicants: lead (Pb 0.088 mg L−1), mercury (Hg 0.084 mg L−1), and pendimethalin (PM 0.355 mg L−1) and their combinations on the behavior, oxidative stress, immunology, biochemistry, and histopathological changes in Nile tilapia. The results show that mortality was evident across all treatment groups and was highest in the mixture (MIX) group, at 33.4%. Some of these behavioral changes included increased mucus secretion, fin rot, and dark skin coloration of the fish, all of which were evidently exacerbated in the MIX group. The erythrocyte and hemoglobin indices presented marked reductions in the MIX and PM groups in comparison to the control group. The MIX group had higher levels of serum creatinine and urea, as well as the liver enzymes alanine aminotransferase, aspartate transaminase, and alkaline phosphatase. They also had higher levels of malondialdehyde and lower levels of total antioxidant capacity, which showed oxidative stress. The stress biomarkers, cortisol and glucose, showed greater impact on the MIX and PM groups. The neurobehavioral assessment demonstrated noticeable decreased acetylcholinesterase levels in PM and MIX-exposed groups. In the serum immunological parameters, levels of nitric oxide and lysozyme were lower, especially in the MIX and PM groups. In all experimental groups, especially the MIX group, the levels of spleen pro-inflammatory cytokine genes were higher. The histopathological examination revealed marked lesions in the gills, liver, and brains in the form of inflammation, necrosis, and circulatory alterations. Among the exposed groups, the MIX group exhibited the highest histopathological changes. Collectively, our findings demonstrated significant toxic effects of heavy metals and herbicides on Nile tilapia, revealing a synergistic impact on both physiological and histopathological responses resulting from combined exposures. The data evidently indicate the ecological hazards associated with heavy metals and herbicides in aquatic ecosystems.

Saravanan M., Vidhya K.

Agaguena R., Zaidi N., Brunelli E., Hamdani A., Macirella R.

Jiang Z., Wan X., Bai X., Chen Z., Zhu L., Feng J.

Li Y., Lu J., Song X., Wang Y., Li Q., Pang Y., Gou M.

The neonicotinoid pesticide acetamiprid has been widely used in agricultural pest control and was frequently detected in the water environment. There have been some studies of the toxic effects of acetamiprid on fish, but studies on aquatic lower vertebrates are still very limited. As a primitive jawless vertebrate, Lethenteron reissneri has a special position in evolution and is now listed as a national second level protected animal in China. The present study aimed to investigate the toxic effect of acetamiprid on the liver of L. reissneri larvae. A conjoint analysis of the transcriptomics and metabolomics was performed to determine the responses of L. reissneri larvae liver to acetamiprid at different concentrations (L for low concentration 25 mg/L and H for high concentration 100 mg/L). Even low concentrations of acetamiprid can cause significant liver damage to L. reissneri larvae in a short period. In omics analyses, 2141 differentially expressed genes (DEGs) and 183 differentially abundant metabolites (DAMs) were identified in the H/Control group, and 229 DEGs and 144 DAMs were identified in the L/C group. Correlation analyses revealed acetamiprid affected the metabolic pathways of L. reissneri larvae liver such as the glycerophospholipid metabolism and arachidonic acid metabolism. This study not only enriches the basis for understanding the toxic effect of acetamiprid exposure to L. reissneri larvae liver and provides more information on the breeding and conservation of L. reissneri, but also further causes attention on toxicity risk from acetamiprid to aquatic lower vertebrate species.

Wang Y., Gu W., Xu Z., Lv L., Wang D., Jin Y., Wang X.

The coexistence of heavy metals and pesticides poses a critical challenge in agricultural ecosystems. Traditional toxicity assessments often focus only on the individual impacts of either pesticides or heavy metals. Here, the untargeted metabolomics and 16 S rRNA sequencing were used to assess the individual and combined effects of cadmium (Cd) and triazophos (TRI) on hook snout carps (Opsariichthys bidens). Cd caused much more serious impacts on hepatic metabolism and gut microbiota than those in TRI. Combined Cd and TRI exposure synergistically affected hepatic metabolism, causing mitochondrial dysfunction and even oxidative damage. Simultaneously, 16 S rRNA sequencing highlighted significant variations in the composition and abundance of gut microbiota. A noteworthy connection emerged between these distinct microbiota profiles and disruptions in energy metabolism, ultimately leading to disorders in metabolites. These findings enhanced the understanding of risks posed by heavy metals and pesticides, providing insights for better environmental risk assessments of aquatic organisms.

Qiu C.B., Tang J., Chen G., Yang H., Liu J.

Xenobiotics like pesticide isoproturon (IPU) and heavy metal cadmium (Cd) are environmental contaminants posing serious impacts on ecosystem. Understanding their toxic and accumulative processes is crucial to uncover insightful mechanisms and minimize health risks. However, the joint effect of IPU and Cd on microorganisms in aquatic ecosystems remains elusive. In this study, Chlamydomonas reinhardtii was selected as a model unicellular organism to evaluate the ecotoxicological effects of IPU and Cd, focusing on biological responses, bioaccumulation capacity, and environmental adaptation. The combined treatment with IPU (0.24 μmol L−1) and/or Cd (20 μmol L−1) for 60 h can induce acute toxicity to C. reinhardtii, reducing chlorophyll and photosynthetic fluorescence, while increasing oxidative damage manifested by lipid membrane peroxides and electrical conductivity. IPU and Cd were accumulated in C. reinhardtii. Interestingly, IPU accumulation in algae was significantly repressed in the presence of Cd, showing a remarkable decrease of 116.7% compared to the IPU treatment alone. Similarly, the Cd concentration in the cells exposed to IPU was reduced by 23.5% compared to Cd treatment alone. Calculation of the bioconcentration factors revealed lower accumulation values of IPU or Cd in algae under Cd+IPU exposure compared to IPU or Cd stress, suggesting an antagonistic interaction between IPU and Cd during absorption by the algae. Furthermore, the activities and transcriptional expression of enzymatic antioxidants such as SOD and APX were significantly induced by Cd stress, whereas the activities of CAT, APX, and PPO significantly increased elevated by IPU. This study provides compelling evidence of the ecotoxicological effects of combined IPU and cadmium contamination on algae, highlighting the potential of algae for bioremediation of environments contaminated with IPU and cadmium.

Machikhin A., Guryleva A., Chakraborty A., Khokhlov D., Selyukov A., Shuman L., Bukova V., Efremova E., Rudenko E., Burlakov A.

AbstractToxic environmental pollutants pose a health risk for both humans and animals. Accumulation of industrial contaminants in freshwater fish may become a significant threat to biodiversity. Comprehensive monitoring of the impact of environmental stressors on fish functional systems is important and use of non‐invasive tools that can detect the presence of these toxicants in vivo is desirable. The blood circulatory system, by virtue of its sensitivity to the external stimuli, could be an informative indicator of chemical exposure. In this study, microscopic photoplethysmography‐based approach was used to investigate the cardiac activity in broad whitefish larvae (Coregonus nasus) under acute exposure to cadmium and phenol. We identified contamination‐induced abnormalities in the rhythms of the ventricle and atrium. Our results allow introducing additional endpoints to evaluate the cardiac dysfunction in fish larvae and contribute to the non‐invasive evaluation of the toxic effects of industrial pollutants on bioaccumulation and aquatic life.

Lv L., Jia F., Deng M., Di S., Chu T., Wang Y.

While combinations of pesticides better represent actual conditions within aquatic ecosystems, the specific toxic effects of these combinations have not been determined yet. The objective of this research was to assess the combined impact of imazalil and azoxystrobin on the hook snout carp (Opsariichthys bidens) and delve into the underlying causes. Our findings indicated that the 4-day LC50 value for imazalil (1.85 mg L−1) was greater than that for azoxystrobin (0.90 mg L−1). When imazalil and azoxystrobin were combined, they presented a heightened effect on the species. Enzyme activities like SOD, CAT, GST, and CarE, along with androgen and estrogen levels, displayed marked differences in most single and combined treatments in comparison to the baseline group. Moreover, four genes (mn-sod, cu-sod, il-1, and esr) related to oxidative stress, immunity, and the endocrine system exhibited more pronounced expression changes when exposed to combined pesticides rather than individual ones. Our tests revealed that the combined use of imazalil and azoxystrobin had more detrimental effect on aquatic vertebrates than when evaluated individually. This finding suggested that future ecological hazard analyses based only on individual tests might not sufficiently safeguard our aquatic ecosystems.

Ríos F., Lechuga M., Lobato-Guarnido I., Fernández-Serrano M.

Surfactants can be found in an ever-widening variety of products and applications, in which the combination of several types of surfactants is used to reinforce their properties, looking for synergistic effects between them. After use, they tend to be discarded into wastewater, ending up in aquatic bodies with concerning harmful and toxic effects. The aim of this study is the toxicological assessment of three anionic surfactants (ether carboxylic derivative, EC) and three amphoteric surfactants (amine-oxide-based, AO), individually and in binary mixtures of them (1:1 w/w), to bacteria Pseudomonas putida and marine microalgae Phaeodactylum tricornutum. Critical Micelle Concentration (CMC) was determined to demonstrate the capacity to reduce surface tension and the toxicity of the surfactants and mixtures. Zeta potential (ζ-potential) and micelle diameter (MD) were also determined to confirm the formation of mixed surfactant micelles. The Model of Toxic Units (MTUs) was used to quantify the interactions of surfactants in binary mixtures and to predict if the concentration addition or response addition principle can be assumed for each mixture. The results showed a higher sensitivity of microalgae P. tricornutum to the surfactants tested and their mixtures than bacteria P. putida. Antagonism toxic effects have been detected in the mixture of EC + AO and in one binary mixture of different AOs; this is to say, the mixtures showed lower toxicity than expected.

Çelebi H., Bahadır T., Şimşek İ., Tulun Ş.

Khatib I., Horyn O., Bodnar O., Lushchak O., Rychter P., Falfushynska H.

Our research sought to determine the molecular and biochemical effects of environmentally relevant exposure to commonly used chloro-s-triazine herbicide terbuthylazine and organophosphate insecticide malathion on zebrafish. To this aim, mature zebrafish were exposed to 2 and 30 µg L−1 terbuthylazine and 5 and 50 µg L−1 malathion alone and in combination for 14 days. Aside from the accumulation of TBARS and protein carbonyls, a decrease in antioxidants and succinate dehydrogenase activity, an increase in oxidized glutathione, and enhanced apoptosis via Caspase-3 and BAX overexpression were observed. Furthermore, terbuthylazine and malathion induced mitochondrial swelling (up to 210% after single exposure and up to 470% after co-exposure) and lactate dehydrogenase leakage (up to 268% after single exposure and up to 570% after co-exposure) in a concentration-dependent manner. Significant upregulation of ubiquitin expression and increased cathepsin D activity were characteristics that appeared only upon terbuthylazine exposure, whereas the induction of IgM was identified as the specific characteristic of malathion toxicity. Meanwhile, no alterations in the zebrafish hypothalamic-pituitary-thyroid axis was observed. Co-exposure increased the adverse effects of individual pesticides on zebrafish. This study should improve the understanding of the mechanisms of pesticide toxicity that lead to fish impairment and biodiversity decline.