Co-exposure of zinc oxide nanoparticles and multi-layer graphenes in blackfish (Capoeta fusca): evaluation of lethal, behavioural, and histopathological effects.

Zinc oxide nanoparticles (ZnO NPs) and multi-layer graphenes (MLGs) are widely used, and due to the lack of appropriate wastewater treatment may end up in the aquatic environment, with unknown consequences to biota. The main purpose of this study was to assess the acute toxicity, histopathological and behavioural changes caused by the exposure of ZnO NPs and MLGs, alone and combined, to the blackfish Capoeta fusca. The estimated mean 96 h-LC50 for ZnO NPs was 4.9 mg L-1 and 68.4 mg L-1 for MLGs. In combination, MLGs increased the acute toxicity of the ZnO NPs. The effects of the different NPs on the gills included hyperplasia, aneurisms, and fusion of the lamellae. In the intestine, exposure to the NPs resulted in an increase in the number and swelling of goblet cells and tissue degeneration. Loss of balance, restlessness, erratic and abnormal swimming patterns were the most common behavioural changes seen in the ZnO NPs' exposed blackfish. In contrast with the acute toxicity findings, MLGs decreased the histopathological and behavioural effects of the ZnO NPs on both gills and intestinal tissues as well as fish behaviour. Our experimental results illustrated insights into the simultaneous exposure assessment of metal-based NPs and carbon nanomaterials, although further research is needed on the interactions exposure of these substances to interpreting the toxicological effects of metal-based nanomaterials seen in exposed organisms.

Influence of environmental conditions on the toxicokinetics of cadmium in the marine copepod Acartia tonsa.

mMarine and estuarine ecosystems are highly productive areas that often act as a final sink for several pollutants, such as cadmium. Environmental conditions in these habitats can affect metal speciation, as well as its uptake and depuration by living organisms. The aim of this study was to assess cadmium uptake and depuration rates in the euryhaline calanoid copepod Acartia tonsa under different pH, salinity and temperature conditions. Cadmium speciation did not vary with changing pH or temperature, but varied with salinity. Free Cd2+ ion activity increased with decreasing salinities resulting in increased cadmium concentrations in A. tonsa. However, uptake rate, derived using free Cd2+ ion activity, showed no significant differences at different salinities indicating a simultaneous combined effect of Cd2+ speciation and metabolic rates for osmoregulation. Cadmium concentration in A. tonsa and uptake rate increased with increasing pH, showing a peak at the intermediate pH of 7.5, while depuration rate fluctuated, thus suggesting that both parameters are mediated by metabolic processes (to maintain homeostasis at pH levels lower than normal) and ion competition at membrane binding sites. Cadmium concentration in A. tonsa, uptake and depuration rates increased with increasing temperature, a trend that can be attributed to an increase in metabolic energy demand at higher temperatures. The present study shows that cadmium uptake and depuration rates in the marine copepod A. tonsa is mostly affected by biological processes, mainly driven by metabolic mechanisms, and to a lesser extent by metal speciation in the exposure medium.

Changes of chemical chronic toxicity to Daphnia magna under different food regimes.

In aquatic ecosystems several stressors may act together and affect the life traits of organisms. Pesticide runoffs are usually associated with high inputs of organic matter and depletion of oxygen in aquatic systems. This study aimed at combining anthropogenic stress (chemicals) and natural stress (food availability) and evaluates their joint effect to the life traits of Daphnia magna. The neonicotinoid insecticide imidacloprid and the heavy metal nickel chloride were used and a 21 d chronic test was carried out to obtain reproduction and growth data. The conceptual model Independent action, usually used for assessing response patterns in chemical mixtures, was used for data interpretation. Results showed an increase in the reproduction and growth pattern of D. magna as food levels increased. Both chemicals significantly impaired the reproduction as well as the somatic growth of the organism while the same happened with food concentrations lower than 3×10(5) cells/mL. It was also observed that food availability did not change the toxicity of imidacloprid and nickel chloride when food levels were higher than 3×10(5) cells/mL. When combined with low food levels, imidacloprid showed a slight increase in toxicity, showing that daphnids become more sensitive with reduced food availability, however in a non-significant way. However, toxicity of nickel appeared to be independent of the food level. Both chemicals induced mortality to the organisms exposed in the absence of food only at the end of the test.

Evidence That a Peptide-Drug/p53 Gene Complex Promotes Cognate Gene Expression and Inhibits the Viability of Glioblastoma Cells.

Glioblastoma multiform (GBM) is considered the deadliest brain cancer. Conventional therapies are followed by poor patient survival outcomes, so novel and more efficacious therapeutic strategies are imperative to tackle this scourge. Gene therapy has emerged as an exciting and innovative tool in cancer therapy. Its combination with chemotherapy has significantly improved therapeutic outcomes. In line with this, our team has developed temozolomide-transferrin (Tf) peptide (WRAP5)/p53 gene nanometric complexes that were revealed to be biocompatible with non-cancerous cells and in a zebrafish model and were able to efficiently target and internalize into SNB19 and U373 glioma cell lines. The transfection of these cells, mediated by the formulated peptide-drug/gene complexes, resulted in p53 expression. The combined action of the anticancer drug with p53 supplementation in cancer cells enhances cytotoxicity, which was correlated to apoptosis activation through quantification of caspase-3 activity. In addition, increased caspase-9 levels revealed that the intrinsic or mitochondrial pathway of apoptosis was implicated. This assumption was further evidenced by the presence, in glioma cells, of Bax protein overexpression-a core regulator of this apoptotic pathway. Our findings demonstrated the great potential of peptide TMZ/p53 co-delivery complexes for cellular transfection, p53 expression, and apoptosis induction, holding promising therapeutic value toward glioblastoma.

Responses of soil microbiome to copper-based materials (nano and bulk) for agricultural applications: An indoor-mesocosm experiment.

The foreseen increasing application of copper-based nanomaterials (Cu-NMs), replacing or complementing existing Cu-agrochemicals, may negatively impact the soil microbiome. Thus, we studied the effects on soil microbiome function and composition of nano copper oxide (nCuO) or copper hydroxide NMs in a commercial (Kocide®3000) or a lab-synthetized formulation (nCu(OH)2) or bulk copper hydroxide (Cu(OH)2-B), at the commonly recommended Cu dose of 50 mg(Cu)kg-1 soil. Microbial responses were studied over 28 days in a designed indoor mesocosm. On day-28, in comparison to non-treated soil (CT), all Cu-treatments led to a reduction in dehydrogenase (95% to 68%), arylsulfatase (41% to 27%), and urease (40% to 20%) activity. There was a 32% increase in the utilization of carbon substrates in the nCuO-treatment and an increased abundance of viable bacteria in the nCu(OH)2-treatment (75% of heterotrophic and 69% of P-solubilizing bacteria). The relative abundance of Acidobacteria [Kocide®3000, nCuO, and Cu(OH)2-B treatments] and Flavobacteriia [nCu(OH)2-treatment] was negatively affected by Cu exposure. The abundance of Cu-tolerant bacteria increased in soils treated with Kocide®3000 (Clostridia) and nCu(OH)2 (Gemmatimonadetes). All Cu-treated soils exhibited a reduced abundance of denitrification-related genes (0.05% of nosZ gene). The DTPA-extractable pool of ionic Cu(II) varied among treatments: Cu(OH)2-B > Kocide®3000 âˆ¼ nCuO>nCu(OH)2, which may explain changes on the soil microbiome composition, at the genera and OTU levels. Thus, our study revealed that Cu-materials (nano and bulk) influence the soil microbiome with implications on its ecological role. It highlights the importance of assessing the impact of Cu-materials under dynamic and complex exposure scenarios and emphasizes the need for specific regulatory frameworks for NMs.

A Systematic Review of Nano- and Microplastic (NMP) Influence on the Bioaccumulation of Environmental Contaminants: Part I-Soil Organisms.

Nano- and microplastics (NMPs) are a group of contaminants that cause concern due to their abundance in the environment, high persistence, and interaction with other contaminants. This review aims to understand the role of NMP in the bioaccumulation of environmental contaminants. For that, a comprehensive literature search was conducted to identify publications that compared the uptake of contaminants in the presence and absence of NMP. In this part I, twenty-eight publications of the terrestrial compartment were analyzed. Two main taxonomic groups were studied, namely, earthworms and terrestrial plants. In earthworms, most studies observed an increase in the bioaccumulation of the contaminants, while in plants, most studies observed a decrease in the bioaccumulation. Changes in bioavailable fractions of contaminants due to NMP presence was the main reason pointed out by the authors for their outcomes. Moreover, biological aspects were also found to be important in defining how NMPs affect bioaccumulation. Dermal damage and changes in contaminant-degrading bacteria in the gut of earthworms caused an increase in bioaccumulation, and root pore blockage was a common reason for the decrease in the bioaccumulation of contaminants in plants. Nevertheless, such effects were mainly observed at high, unrealistic NMP concentrations. Finally, knowledge gaps were identified, and the limitations of this systematic review were presented.

Zn-Al layered double hydroxides induce embryo malformations and impair locomotion behavior in Danio rerio.

Layered double hydroxides (LDHs) are stimuli-responsive anionic nanoclays. The vast possibilities of using LDHs can lead to their existence in the ecosystem, raising a question of potential ecological concern. However, little is known about the effect of these nanomaterials on freshwater organisms. The present study aimed to assess the ecotoxicological effects of Zinc-Aluminium LDH-nitrate (ZnAl LDH-NO3) in zebrafish (Danio rerio) early life stages. The endpoints measured were mortality, malformations and hatching rate after exposure of D. rerio embryos and larvae to ZnAl LDH-NO3 following the OECD 236 guideline. The behavioral, biochemical (markers of oxidative stress and neurotoxicity), and molecular (at DNA level) alterations were also assessed using sub-lethal concentrations. No observable acute effects were detected up to 415.2 mg LDH/L while the 96 h-LC50 was estimated as 559.9 mg/L. Tested LDH caused malformations in D. rerio embryos, such as pericardial edema, incomplete yolk sac absorption and tail deformities (96 h-EC50 = 172.4 mg/L). During the dark periods, the locomotor behavior in zebrafish larvae was affected upon ZnAl LDH-NO3 exposure. However, no significant biochemical and molecular changes were recorded. The present findings suggest that ZnAl LDH-NO3 can be regarded as a non-toxic nanomaterial towards D. rerio (E/LC50 > > 100 mg/L) although impairment of the locomotion behavior on zebrafish embryos can be expected at concentrations below 100 mg/L.

Systematic Review of Nano- and Microplastics' (NMP) Influence on the Bioaccumulation of Environmental Contaminants: Part II-Freshwater Organisms.

Nano- and microplastic fragments (NMPs) exist ubiquitously in all environmental compartments. The literature-based evidence suggests that NMPs interact with other environmental contaminants in freshwater ecosystems through sorption mechanisms, thereby playing a vector role. Chemically bound NMPs can translocate throughout the environment, reaching long distances from the contaminant discharge site. In addition, they can be ab/adsorbed by freshwater organisms. Although many studies show that NMPs can increase toxicity towards freshwater biota through the carrier role, little is known regarding their potential to influence the bioaccumulation of environmental contaminants (EC) in freshwater species. This review is part II of a systematic literature review regarding the influence of NMPs on bioaccumulation. Part I deals with terrestrial organisms and part II is devoted to freshwater organisms. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA ScR) was used for the literature search and selection. Only studies that assessed the bioaccumulation of EC in the presence of NMPs and compared this with the bioaccumulation of the isolated EC were considered. Here, we discuss the outcome of 46 papers, considering NMPs that induced an increase, induced a decrease, or caused no effect on bioaccumulation. Lastly, knowledge gaps are identified, and future directives for this area of research are discussed.

Assessing the impact of antineoplastic drugs in the aquatic environment: State of the art and future perspective for freshwater organisms.

Since the late 70s, the continuous pharmaceuticals` input into the environment has raised concerns regarding the eventual risk posed by such compounds to human and environmental health. A major group of pharmaceuticals in terms of environmental impact are the antineoplastic agents (AAs). Herein, we followed a systematic review method to retrieve antineoplastic agents (AAs') ecotoxicological information regarding freshwater species. In this analysis, data from diverse taxonomic groups, from microorganisms to vertebrate species, looked at different levels of biological organization, including cell lines. Furthermore, this review gathers ecotoxicological parameters (EC50 and LC50) for imatinib (IM), cisplatin (CisPt), and 5-fluorouracil (5-FU) in species sensitivity distribution (SSD) curves and estimates the hazard concentration (HC5) considering the protection of 95% of the ecological community. Lastly, we suggest how we can improve AAs' Environmental Risk Assessment (ERA), considering potential adoptable toxicity endpoints, test duration, AAs metabolites testing, and AAs mixture exposure.

Environmental Hazard of Anticancer Drugs: State of the Art and Future Perspective for Marine Organisms.

Pharmaceutical compounds represent a class of emerging contaminants present in the environment. Their intense (and increasing) use in human and veterinary medicine leads to their discharge, mainly via human excretion, into wastewater treatment plants where their removal is inefficient. A specific class of pharmaceuticals used to fight cancer, known as antineoplastic or anticancer drugs, has gained increased attention regarding their possible environmental hazard due to their pharmacological properties, which include the nonselective targeting of DNA replication mechanisms and cell division processes, potentially inducing cell apoptosis. To date, there is limited information concerning the effects of anticancer drugs and/or their metabolites in species inhabiting freshwater environments, let alone marine and estuarine compartments. In the present review, we aimed to assemble information regarding the impact that anticancer drugs have on biological traits of marine species, to identify gaps in the current environmental hazard assessment, and to make recommendations to promote an efficient environmental hazard assessment of anticancer drugs in the marine environment. Environ Toxicol Chem 2022;41:1793-1807. © 2022 SETAC.

Terrestrial organisms react differently to nano and non-nano Cu(OH)2 forms.

The application of nanomaterials in agriculture is deemed as a promising strategy to increase the sector's sustainability. Nanopesticides are expected to improve solutions for pest/disease management, while reducing adverse effects to ecosystems, in accordance with the European Green Deal strategy. Hitherto, nanopesticide research has mostly focused on assessing effects to target species or crops, and less attention has been devoted to non-target soil species. In this study, we explored whether three copper hydroxide-based forms (nano and non-nano) show different toxicity and accumulation patterns in two terrestrial invertebrates, the isopod Porcellionides pruinosus and the mealworm larvae Tenebrio molitor. Toxicity and bioaccumulation experiments were performed and time-course toxicity and toxicokinetics analyzed and modelled. We found important differences in copper sensitivity and accumulation: T. molitor was more resistant and able to eliminate copper compared to P. pruinosus. The nanopesticide mostly elicited lower effects for both species. Slower toxicokinetics by the nanopesticide and lower bioaccumulative potential to P. pruinosus must be partially responsible for the differences in toxicity. Although no toxicokinetics differences were found in T. molitor between Cu forms, distinct negative effects on growth must reflect different energetic costs for copper regulation. Even though effects on toxicity and bioaccumulation are species-specific, copper hydroxide-based nanopesticides may cause less adverse effects to soil organisms than conventional products, being a good solution for reducing the environmental impact. CAPSULE: Copper hydroxide-based nanopesticide was less toxic and bioaccumulative to soil organisms than conventional copper hydroxide products, being a good solution for reducing the environmental impact.

Mixture toxicity prediction of substances from different origin sources in Daphnia magna.

Due to several anthropogenic activities, water bodies have been heavily impacted by contaminants identified in aquatic ecosystems, including pharmaceuticals, personal care products, agricultural and industrial chemicals. Risk assessment based on chemical mixtures is still default in many monitoring studies, with decisions being based solely on a chemical-by-chemical basis. The present study aimed to improve risk assessment procedures in water bodies by focusing on mixtures of chemical substances of different origins. The goal was to analyze potential interactions occurring at different complexity levels (binary and quaternary mixtures) using standardised toxicity assays. Mixture toxicity effects were assessed using Daphnia magna as the model organism and the compounds sodium fluoride, boric acid, ammonium hydroxide and acetaminophen as general representatives of contaminants in the aquatic ecosystem. The results revealed interactions between the compounds, mainly showing antagonism but also dose level and dose ratio-dependent deviations. Overall antagonism was the dominant deviation pattern, particularly at low doses, though synergism was also detected at higher doses or specific ratios. Synergism at low doses was found for the binary mixture of ammonium hydroxide and acetaminophen, two common pollutants, which denotes an enhanced risk to aquatic ecosystems. Independent Action provided more accurate predictions for the quaternary mixture, whereas Concentration Addition overestimated the toxicity of the mixture. Regarding the environmental risk assessment of water bodies, the interaction between chemicals in a mixture should not be neglected. The complexity of the mixture interactions found in the present study highlights the importance of complementing chemical screenings of water bodies with mixture toxicity data, particularly when considering chemicals of multiple origins whose joint action remains unknown.

Effects of binary mixtures on the life traits of Daphnia magna.

The environment is constantly exposed to a cocktail of contaminants mainly due to human activities. Because polluted ecosystems are characterized by an amalgam of chemical compounds, the objective of the present study was to assess the joint effect of chemical mixtures to the life--history traits of Daphnia magna Straus. For that a binary mixture of two neonicotinoid insecticides, imidacloprid and thiacloprid, and another one of imidacloprid with nickel chloride were tested. Theoretical models have been developed and applied in studies with chemical mixtures, predicting toxicity based on their modes of action: concentration addition (CA) and independent joint action (IA) models. Still there are cases where deviations are observed (e.g. synergistic or antagonistic behaviors, dose ratio or level dependency). In this study, the effects of the individual compounds and their mixtures were studied in a chronic test where reproduction, survival and body length were evaluated in D. magna. Regarding single compound effects, it was observed that the most toxic was nickel chloride followed by thiacloprid and imidacloprid. For the mixture exposure of imidacloprid and thiacloprid, a synergistic pattern was observed in the sublethal doses used for the number of neonates produced, while for the body length the best fit was shown with the CA model. In the mixture exposure of imidacloprid and nickel, no deviation from the IA was observed for the neonate production data; for the body length parameter, a synergistic pattern was observed in low doses of the chemicals while an antagonistic pattern was observed.

Site-specific hazard evaluation for improved groundwater risk assessment.

Groundwater represents one of the most important natural water resources worldwide. Contamination is a key driver in sustaining water quality to populations and the environment. Therefore, it is crucial to look at contamination and potential effects. Within the WaterJPI project "We-Need - WatEr NEEDs, Availability, Quality and Sustainability", the Cremona and the Bologna Aquifers (Italy) were chosen as case studies since both aquifers represent two major Italian water resources of the Emilia-Romagna region. Aiming for a site-specific groundwater hazard assessment, the groundwaters from the Cremona and Bologna aquifers were simulated by preparing synthetic waters, CSW and BSW, respectively. Boron (as boric acid), fluoride (as sodium fluoride), and ammonium (as ammonium hydroxide), detected in the aquifers, were used to assess potential negative impacts on groundwater systems using aquatic organisms. Acute toxicity tests with Daphnia magna and Fish Embryo Toxicity Tests (FET) with Danio rerio were performed in the CSW and BSW synthetic waters and respective culture media, and toxicity was assessed for each organism. Boron, fluoride and ammonium had no ecological hazard effects at the concentrations detected in the groundwaters. Besides, a crucial result from this study regards the use of different media when addressing toxicity assessment. In this case, it was observed that toxicity was media and organism dependent. Therefore, adapting testing protocols for higher relevance should be considered for site-specific hazard assessment.

Bioaccumulation and toxicokinetics of zinc oxide nanoparticles (ZnO NPs) co-exposed with graphene nanosheets (GNs) in the blackfish (Capoeta fusca).

In this study, we investigated the bioaccumulation and toxicokinetics of zinc oxide nanoparticles (ZnO NPs) alone and in the presence of graphene nanosheets (GNs) in the blackfish (Capoeta fusca). Blackfish were exposed via water to two ZnO NPs concentrations alone or as a combination with GNs and uptake of Zn into the gills, intestine, liver, and kidney was assessed at 7, 14 and 28 d. Zn elimination from these tissues was then assessed after a further 7, 14 and 28 d in clean water for both ZnO NPs concentrations and combined ZnO NPs/GN exposures. In the body tissues analyzed of exposed fish, the highest amounts of Zn occurred in the intestine and the lowest amount in the liver. Zn levels in blackfish after 28 d of exposure were higher in all treatment groups compared to those on 7 d (p < 0.05). For both ZnO NPs exposure concentrations, the highest amount of Zn was eliminated from the intestine, followed by the gills. Furthermore, elimination kinetics for both ZnO NPs concentrations alone and in combination with GNs showed that the shortest half-life for Zn is occurring in the intestine. Moreover, uptake rates of Zn in fish exposed to ZnO NPs + GNs followed the same pattern observed for the ZnO NP, with intestine and gills having the highest levels followed by kidney and liver. Thus, we show accumulation and elimination of Zn from ZnO NPs in blackfish depends on the tissue, exposure concentration and duration, and is dependent on the presence of GNs.

Effects of nanostructure antifouling biocides towards a coral species in the context of global changes.

Biofouling prevention is one of the biggest challenges faced by the maritime industry, but antifouling agents commonly impact marine ecosystems. Advances in antifouling technology include the use of nanomaterials. Herein we test an antifouling nano-additive based on the encapsulation of the biocide 4,5-dichloro-2-octyl-4-isothiazolin-3-one (DCOIT) in engineered silica nanocontainers (SiNC). The work aims to assess the biochemical and physiological effects on the symbiotic coral Sarcophyton cf. glaucum caused by (1) thermal stress and (2) DCOIT exposure (free or nanoencapsulated forms), in a climate change scenario. Accordingly, the following hypotheses were addressed: (H1) ocean warming can cause toxicity on S. cf. glaucum; (H2) the nanoencapsulation process decreases DCOIT toxicity towards this species; (H3) the biocide toxicity, free or encapsulated forms, can be affected by ocean warming. Coral fragments were exposed for seven days to DCOIT in both free and encapsulated forms, SiNC and negative controls, under two water temperature regimes (26 °C and 30.5 °C). Coral polyp behavior and photosynthetic efficiency were determined in the holobiont, while biochemical markers were assessed individually in the endosymbiont and coral host. Results showed transient coral polyp retraction and diminished photosynthetic efficiency in the presence of heat stress or free DCOIT, with effects being magnified in the presence of both stressors. The activity of catalase and glutathione-S-transferase were modulated by temperature in each partner of the symbiosis. The shifts in enzymatic activity were more pronounced in the presence of free DCOIT, but to a lower extent for encapsulated DCOIT. Increased levels of oxidative damage were detected under heat conditions. The findings highlight the physiological constrains elicited by the increase of seawater temperature to symbiotic corals and demonstrate that DCOIT toxicity can be minimized through encapsulation in SiNC. The presence of both stressors magnifies toxicity and confirm that ocean warming enhances the vulnerability of tropical photosynthetic corals to local stressors.

Toxicokinetics of cadmium in Palaemon varians postlarvae under waterborne and/or dietary exposure.

The present study assessed cadmium uptake and depuration rates in the euryhaline estuarine shrimp Palaemon varians under different exposure routes. Postlarval shrimp were exposed for 4 d under different exposure routes: contaminated water, contaminated diet, and a 2-way exposure scenario where both contaminated water and diet were used. After exposure, postlarval shrimp were transferred to a clean medium and fed a noncontaminated diet for 96 h. Bioaccumulation via the different exposure routes was modeled with a standard first-order, one-compartment toxicokinetics model and one with an additional parameter reflecting an inert fraction or storage compartment. The simultaneous 2-way exposure (through water and diet) resulted in accumulation being almost twice as high as the sum of the individual exposure routes, thus indicating that accumulation from multiple routes may be more than additive. Cadmium uptake from water was faster than uptake from food maintained for 48 h at that same cadmium concentration. Shrimp were unable to eliminate cadmium from their body, showing no depuration during 96 h after exposure via different routes, thus suggesting that a longer depuration period is needed. Model comparisons did not provide a significantly better fit when the model included the presence of an inert fraction. The present study highlights the importance of assessing accumulation using multiple exposure routes compared with individual routes because the latter may underestimate bioaccumulation. Environ Toxicol Chem 2018;37:1614-1622. © 2018 SETAC.

Bioaccumulation of silver in Daphnia magna: Waterborne and dietary exposure to nanoparticles and dissolved silver.

Silver nanoparticles (Ag-NP) are incorporated into commercial products as antimicrobial agents, which potentiate their emission to the environment. The toxicity of Ag-NP has been associated with the release of Ag ions (Ag+), which are more toxic to aquatic organisms than Ag-NP. In this study, a toxicokinetics approach was applied to compare the potential of Daphnia magna to accumulate Ag from either Ag-NP or AgNO3 through different exposure routes: a) water, b) diet and c) water and diet. A one-compartment kinetics model was applied to describe the development of Ag body concentrations over time and derive uptake (k1w; k1d) and elimination (k2) rate constants. Under water-only exposure, AgNO3 induced higher Ag uptake rate constants and bioconcentration factors when compared to Ag-NP. For dietary exposure, no differences in Ag concentrations in D. magna, along with the kinetics parameters, were found for both Ag forms. Simultaneous water and dietary exposures to Ag-NP induced higher Ag concentrations in D. magna compared to AgNO3. In this combined exposure, uptake from water explains most for the increase in Ag body concentration in D. magna for Ag-NP exposure, whereas uptake from the diet was the major contributor for the increase in Ag concentration in D. magna under AgNO3 exposure. Biomagnification was not observed for any of the exposure routes applied in this study, neither for Ag-NP nor for AgNO3.

Ecotoxicity and genotoxicity of cadmium in different marine trophic levels.

Cadmium ecotoxicity and genotoxicity was assessed in three representative species of different trophic levels of marine ecosystems - the calanoid copepod Acartia tonsa, the decapod shrimp, Palaemon varians and the pleuronectiform fish Solea senegalensis. Ecotoxicity endpoints assessed in this study were adult survival, hatching success and larval development ratio (LDR) for A. tonsa, survival of the first larval stage (zoea I) and post-larvae of P. varians, egg and larvae survival, as well as the presence of malformations in the larval stage of S. senegalensis. In vivo genotoxicity was assessed on adult A. tonsa, the larval and postlarval stage of P. varians and newly hatched larvae of S. senegalensis using the comet assay. Results showed that the highest sensitivity to cadmium is displayed by A. tonsa, with the most sensitive endpoint being the LDR of nauplii to copepodites. Sole eggs displayed the highest tolerance to cadmium compared to the other endpoints evaluated for all tested species. Recorded cadmium toxicity was (by increasing order): S. senegalensis eggs < P. varians post-larvae < P. varians zoea I < S. senegalensis larvae < A. tonsa eggs < A. tonsa LDR. DNA damage to all species exposed to cadmium increased with increasing concentrations. Overall, understanding cadmium chemical speciation is paramount to reliably evaluate the effects of this metal in marine ecosystems. Cadmium is genotoxic to all three species tested and therefore may differentially impact individuals and populations of marine taxa. As A. tonsa was the most sensitive species and occupies a lower trophic level, it is likely that cadmium contamination may trigger bottom-up cascading effects in marine trophic interactions.