There is a global research interest in metal nanoparticles (MNPs) due to their diverse applications, rapidly increasing use, and increased presence in the aquatic environment. Currently, most MNPs... Show moreThere is a global research interest in metal nanoparticles (MNPs) due to their diverse applications, rapidly increasing use, and increased presence in the aquatic environment. Currently, most MNPs in the environment are at levels unlikely to cause overt toxicity. Sub-lethal effects that MNPs may induce, notable immunotoxicity, could however have significant health implications. Thus, deciphering the immunological interactions of MNPs with aquatic organisms constitutes a much-needed area of research. In this article, we critically assess the evidence for immunotoxic effects of MNPs in bivalves and fish, as key wildlife sentinels with widely differing ecological niches that are used as models in ecotoxicology. The first part of this review details the properties, fate, and fundamental physicochemical behavior of MNPs in the aquatic ecosystem. We then consider the toxicokinetics of MNP uptake, accumulation, and deposition in fish and bivalves. The main body of the review then focuses on immune reactions in response to MNPs exposure in bivalves and fish illustrating their immunotoxic potential. Finally, we identify major knowledge gaps in our current understanding of the implications of MNPs exposure for immunological functions and the associated health consequences for bivalves and fish, as well as the general lessons learned on the immunotoxic properties of the emerging class of nanoparticulate contaminants in fish and bivalves. Show less
The development of affordable and efficient technologies for the removal of pharmaceuticals and personal care products (PPCPs) from water has recently been the subject of extensive attention. In... Show moreThe development of affordable and efficient technologies for the removal of pharmaceuticals and personal care products (PPCPs) from water has recently been the subject of extensive attention. In this study, a black phosphorus/graphitic carbon nitride (BP-g-C3N4) heterostructure is fabricated as an extremely active metal-free photocatalyst via a newly-developed exfoliation strategy. The BP-g-C3N4 shows an 11 times better decomposition rate of a representative PPCPs-type pollutant, indomethacin (IDM), compared to the widely used P25 TiO2 under real-sunlight illumination. Also, its visible-light activity is even better than that of the best photocatalysts previously developed, but only consumes 1/10-1/4 of the catalyst. The results show that BP performs a cocatalyst-like behavior to catalyze the generation of reactive oxygen species, thus speeding up the decomposition of IDM. In addition, the BP-g-C3N4 photocatalyst also exhibits excellent IDM removal efficiency in authentic water matrices (tap water, surface water, and secondarily treated sewage effluent). Large-scale application demonstration under natural sunlight further reveals the practicality of BP-g-C3N4 for real-world water treatment operations. Our work will open up new possibilities in the development of purely metal-free photocatalysts for "green" environmental remediation applications. (C) 2021 Elsevier B.V. All rights reserved. Show less
Various modern products have metallic nanoparticles (MNPs) embedded to enhance products performance. Technological advances enable nowadays even multiple hybrid nanoparticles. Consequently, the... Show moreVarious modern products have metallic nanoparticles (MNPs) embedded to enhance products performance. Technological advances enable nowadays even multiple hybrid nanoparticles. Consequently, the future co-release of multiple MNPs will inevitably result in the presence of MNP mixtures in the environment. An important question is if the responses of mixtures of MNPs can be dealt with in a similar way as with the responses of biota to mixtures of metal salts. Moreover, natural organic matter (NOM) is an important parameter affecting the behavior and effect of MNPs. Herein, we determined the joint toxicity and accumulation of copper nanoparticles (CuNPs) and zinc oxide nanoparticles (ZnONPs) in Daphnia magna in the absence and presence of Suwannee River natural organic matter (SR-NOM), compared to the joint toxicity and accumulation of corresponding metal salts. The results of toxicity testing showed that the joint toxicity of CuNPs + ZnONPs was greater than the single toxicity of CuNPs or ZnONPs. The joint toxic action of CuNPs + ZnONPs was additive or more-than-additive for D. magna. A similar pattern was found in the toxicity of the mixtures of Cu- and Zn-salts from the literature data. The presence of SR-NOM had no significant impact on the joint toxicity of CuNPs + ZnONPs. The calculated component-specific contribution to overall toxicity indicated that SR-NOM increased the relative contribution of dissolved ions released from the MNPs to the toxicity of the binary mixtures at high-effect concentrations of individual MNPs. Moreover, dissolved Zn-ions released from the ZnONPs were found to dominate the joint toxicity of CuNPs + ZnONPs in the presence of SR-NOM. Furthermore, the results of the accumulation experiment displayed that the presence of SR-NOM significantly enhanced the accumulation of either CuNPs or ZnONPs in D. magna exposed to the MNP mixtures. Show less
Le, T.T.Y.; Milen, N.; Grabner, D.; Hendriks, A.J.; Peijnenburg, W.J.G.M.; Sures, B. 2022
A toxicokinetic-toxicodynamic model was constructed to delineate the exposure-response causality. The model could be used: to predict metal accumulation considering the influence of water chemistry... Show moreA toxicokinetic-toxicodynamic model was constructed to delineate the exposure-response causality. The model could be used: to predict metal accumulation considering the influence of water chemistry and biotic ligand characteristics; to simulate the dynamics of subcellular partitioning considering metabolism, detoxification, and elimination; and to predict chronic toxicity as represented by biomarker responses from the concentration of metals in the fraction of potentially toxic metal. The model was calibrated with data generated from an experiment in which the Zebra mussel Dreissena polymorpha was exposed to Cu at nominal concentrations of 25 and 50 mu g/L and with varied Na+ concentrations in water up to 4.0 mmol/L for 24 days. Data used in the calibration included physicochemical conditions of the exposure environment, Cu concentrations in subcellular fractions, and oxidative stress-induced responses, i.e. glutathione-S-transferase activity and lipid peroxidation. The model explained the dynamics of subcellular Cu partitioning and the effect mechanism reasonably well. With a low affinity constant for Na+ binding to Cu2+ uptake sites, Na+ had limited influence on Cu2+ uptake at low Na+ concentrations in water. Copper was taken up into the metabolically available pool (MAP) at a largely higher rate than into the cellular debris. Similar Cu concentrations were found in these two fractions at low exposure levels, which could be attributed to sequestration pathways (metabolism, detoxification, and elimination) in the MAP. However, such sequestration was inefficient as shown by similar Cu concentrations in detoxified fractions with increasing exposure level accompanied by the increasing Cu concentration in the MAP. Show less
Nanoforms can be manufactured in plenty of variants by differing their physicochemical properties and toxicokinetic behaviour which can affect their hazard potential. To avoid testing of each... Show moreNanoforms can be manufactured in plenty of variants by differing their physicochemical properties and toxicokinetic behaviour which can affect their hazard potential. To avoid testing of each single nanomaterial and nanoform variation and subsequently save resources, grouping and read-across strategies are used to estimate groups of substances, based on carefully selected evidence, that could potentially have similar human health and environmental hazard impact. A novel computational similarity method is presented aiming to compare doseresponse curves and identify sets of similar nanoforms. The suggested method estimates the statistical model that best fits the data by leveraging pairwise Bayes Factor analysis to compare pairs of curves and evaluate whether each of the nanoforms is sufficiently similar to all other nanoforms. Pairwise comparisons to benchmark materials are used to define threshold similarity values and set the criteria for identifying groups of nanoforms with comparatively similar toxicity. Applications to use case data are shown to demonstrate that the method can support grouping hypotheses linked to a certain hazard endpoint and route of exposure. Show less
Xiao, Y.; Ma, J.; Xian, J.; Peijnenburg, W.J.G.M.; Du, Y.; Tian, D.; ... ; Lihua, T 2022
In recent years, various ecotoxicological test guidelines and (technical) guidance documents have been evaluated and updated with regard to their applicability to nanomaterials (NMs). Several of... Show moreIn recent years, various ecotoxicological test guidelines and (technical) guidance documents have been evaluated and updated with regard to their applicability to nanomaterials (NMs). Several of these have currently reached official regulatory status. Ensuring their harmonized implementation with previously recognized methods for ecotoxicitytesting of chemicals is a crucial next step towards effective and efficient regulation of NMs. In the present study, we evaluated the feasibility of assessing multigenerational effects in the first generation of offspring derived from exposed Daphnia magna whilst maintaining test conditions in accordance with regulatory test guidelines and guidance documents for NMs. To do so, we integrated the recommendations for ecotoxicological testing of NMs as defined in OECD Guidance Document 317 into an extended long-term D. magna reproduction test method (OECD Test Guideline 211) and assessed effects of two poorly soluble NMs (nTiO2 and nCeO2). Our results show adverse effects on life-history parameters of D. magna exposed to the selected nanomaterials within the range of reported environmental concentrations. We argue that conforming to OECD test guidelines and accompanying guidance for nanomaterials is feasible when performing D. magna reproduction tests and can minimize unnecessary duplication of similar experiments, even when extensions to the standardized test setup are added. Show less
Loosli, F.; Rasmussen, K.; Rauscher, H.; Cross, R.; Bossa, N.; Peijnenburg, W.J.G.M.; ... ; Kammer, F. von der 2022
The current debate on hazards associated with sub-micron sized plastics is hampered by a lack of quantitative data on the uptake and biological fate of plastics in organisms. Analytical methods... Show moreThe current debate on hazards associated with sub-micron sized plastics is hampered by a lack of quantitative data on the uptake and biological fate of plastics in organisms. Analytical methods should be developed to identify, characterize, and quantify sub-micron particulate plastic in biota to understand their biological fate in terms of biodistribution, localization, bioaccumulation and clearance. Here we give a perspective on a promising workflow of sample preparation methods and techniques that could enable analysis of sub-micron plastics in biological matrices and discuss their application for biological fate studies of particulate plastic in organisms. We also expect these methods to be largely transferrable to studies considering sub-micron plastics in food, consumer products, human and some environmental compartments. (c) 2021 Elsevier Ltd. All rights reserved. Show less
Le, T.T.Y.; Grabner, D.; Nachev, M.; Garcia, M.R.; Balsa-Canto, E.; Peijnenburg, W.J.G.M.; ... ; Sures, B. 2021
A toxicokinetic-toxicodynamic model based on subcellular metal partitioning is presented for simulating chronic toxicity of copper (Cu) from the estimated concentration in the fraction of... Show moreA toxicokinetic-toxicodynamic model based on subcellular metal partitioning is presented for simulating chronic toxicity of copper (Cu) from the estimated concentration in the fraction of potentially toxic metal (PTM). As such, the model allows for considering the significance of different pathways of metal sequestration in predicting metal toxicity. In the metabolically available pool (MAP), excess metals above the metabolic requirements and the detoxification and elimination capacity form the PTM fraction. The reversibly and irreversibly detoxified fractions were distinguished in the biologically detoxified compartment, while responses of organisms were related to Cu accumulation in the PTM fraction. The model was calibrated using the data on Cu concentrations in subcellular fractions and physiological responses measured by the glutathione S-transferase activity and the lipid peroxidation level during 24-day exposure of the Zebra mussel to Cu at concentrations of 25 and 50 mu g/L and varying Na+ concentrations up to 4.0 mmol/L. The model was capable of explaining dynamics in the subcellular Cu partitioning, e.g. the trade-off between elimination and detoxification as well as the dependence of net accumulation, elimination, detoxification, and metabolism on the exposure level. Increases in the net accumulation rate in the MAP contributed to increased concentrations of Cu in this fraction. Moreover, these results are indicative of ineffective detoxification at high exposure levels and spill-over effects of detoxification. Show less
Plant physiological and metabolic processes are modulated by rhythmic gene expression in a large part. Meanwhile, plants are also regulated by rhizosphere microorganisms, which are fed by root... Show morePlant physiological and metabolic processes are modulated by rhythmic gene expression in a large part. Meanwhile, plants are also regulated by rhizosphere microorganisms, which are fed by root exudates and provide beneficial functions to their plant host. Whether the biorhythms in plants would transfer to the rhizosphere microbial community is still uncertain and their intricate connection remains poorly understood. Here, we investigated the role of the Arabidopsis circadian clock in shaping the rhizosphere microbial community using wild-type plants and clock mutants (cca1-1 and toc1-101) with transcriptomic, metabolomic and 16S rRNA gene sequencing analysis throughout a 24-h period. Deficiencies of the central circadian clock led to abnormal diurnal rhythms for thousands of expressed genes and dozens of root exudates. The bacterial community failed to follow obvious patterns in the 24-h period, and there was lack of coordination with plant growth in the clock mutants. Our results suggest that the robust rhythmicity of genes and root exudation due to circadian clock in plants is an important driving force for the positive succession of rhizosphere communities, which will feedback on plant development. Show less
Le, T.T.Y.; Nachev, M.; Grabner, D.; Garcia, M.R.; Balsa-Canto, E.; Hendriks, A.J.; ... ; Sures, B. 2021
Chronic toxicity of copper (Cu) at sublethal levels is associated with ionoregulatory disturbance and oxidative stress. These factors were considered in a toxicokinetic-toxicodynamic model in the... Show moreChronic toxicity of copper (Cu) at sublethal levels is associated with ionoregulatory disturbance and oxidative stress. These factors were considered in a toxicokinetic-toxicodynamic model in the present study. The ionoregulatory disturbance was evaluated by the activity of the Na+/K+-ATPase enzyme (NKA), while oxidative stress was presented by lipid peroxidation (LPO) and glutathione-S-transferase (GST) activity. NKA activity was related to the binding of Cu2+ and Na+ to NKA. LPO and GST activity were linked with the simulated concentration of unbound Cu. The model was calibrated using previously reported data and empirical data generated when zebra mussels were exposed to Cu. The model clearly demonstrated that Cu might inhibit NKA activity by reducing the number of functional pump sites and the limited Cu-bound NKA turnover rate. An ordinary differential equation was used to describe the relationship between the simulated concentration of unbound Cu and LPO/GST activity. Although this method could not explain the fluctuations in these biomarkers during the experiment, the measurements were within the confidence interval of estimations. Model simulation consistently shows nonsignificant differences in LPO and GST activity at two exposure levels, similar to the empirical observation. Show less
For the soluble metallic nanoparticles (NPs), which forms (particles [NP(particle)] vs. dissolved ions [NP(ion)]) are the main cause of toxicity of the NP suspension (NP(total)) remains uncertain.... Show moreFor the soluble metallic nanoparticles (NPs), which forms (particles [NP(particle)] vs. dissolved ions [NP(ion)]) are the main cause of toxicity of the NP suspension (NP(total)) remains uncertain. In the present study, soybean was exposed to Cu NPs in a hydroponic system to determine how natural organic matter (NOM; 10 mg/l) and concentration of Cu NP(total) (2-50 mg/l) affect the relative contributions of Cu NP(particle) and Cu NP(ion) to the overall toxicity. We found that NOM mitigated the phytotoxicity of Cu NP(particle) more significantly than that of Cu salt. When no NOM was added, Cu NP(particle) rather than Cu NP(ion) was the main contributor to the observed toxicity regardless of the concentration of Cu NP(total). However, NOM tended to reduce the relative contribution of Cu NP(particle) to the toxicity of Cu NP(total). Especially at a low concentration of Cu NP(total) (2 mg/l), the toxicity of Cu NP(total) mainly resulted from Cu NP(ion) in the presence of NOM (accounting for >= 70% of the overall toxicity). This might be attributable to the combined effects of increased dissolution of Cu NPs and steric-electrostatic hindrance between Cu NP(particle) and the soybean roots caused by NOM. Fulvic acids (FAs) tended to reduce the role of Cu NP(particle) in the overall toxicity more effectively than humic acids (HAs), which might partially be due to the higher extent of Cu NP dissolution on FA treatment than in HA treatment. Our results suggest that because of the relatively low metallic NP concentration and the presence of NOM in natural water, NP(ion) are likely problematic, which can inform management and mitigation actions. Environ Toxicol Chem 2021;00:1-11. (c) 2021 SETAC Show less
Copper oxide nanoparticles (CuO NPs) are one of the most widely used materials owing to their excellent properties such as thermal and photochemical stability, superconductivity, and high... Show moreCopper oxide nanoparticles (CuO NPs) are one of the most widely used materials owing to their excellent properties such as thermal and photochemical stability, superconductivity, and high electrochemical activity. Once they enter the environment, Cu2+ may be released in water, which alters the behavior and toxicity of CuO NPs. The present study thus investigated the dissolution of CuO NPs (40 nm) in the presence of tannic acid (TA), a model chemical of dissolved organic matter. The adsorption of TA decreased the hydrodynamic diameter of CuO NPs and increased the zeta potential of the suspension. Although the adsorption of TA on particle surface improved the dispersion of CuO NPs, their dissolution extents were all reduced at TA concentration up to 55.4 mg C L−1. At pH 5, the contributions of TA complexed Cu to the overall dissolution increased up to 37.8% as a function of TA concentrations. All the findings shown above approved that the strong adsorption of TA played a dominant role in preventing the dissolution of CuO NPs. Show less
