Interactive effects between components in binary mixtures of zinc sulfate and iron oxide nanoparticles on Daphnia magna

Abstract

Backgrounds: The concern in the toxicological impact of nanomaterials on aquatic organisms has grown, due to the high adsorption capacity for (in) organic compounds in the aquatic environment. In order to evaluate the toxicity of mixtures composed with metal ion and metal oxide nanoparticles and the interaction between components in binary mixtures, we tested the mixture toxicity of iron oxide nanoparticles (i.e., PVP-Fe3O4 NPs) and zinc sulfate (ZnSCU) on Daphnia magna. Methods: The toxicity of binary mixtures with different concentration-combinations were identified by the effective concentration values (ECxmix) based on the concentration-response curves. Concentration addition index (CAI) and effect addition index (EAI) were applied for examining the interaction between components in binary mixtures. Results: The findings from this study implied the ZnSO4 had a high toxic effect on D. magna more than PVP-Fe3O4 NPs and the synergistic toxicity in binary mixtures were depended on the toxic effects of ZnSO4 and their exposure concentration rather than those of PVP-Fe3O4 NPs. Interestingly, the antagonistic effects between ZnSO4 and PVP-Fe3O4 NPs in binary mixtures showed in the high concentration-combinations suggesting that antagonism in toxicity may be due to the high adsorption capacity of PVP-Fe3O4 NPs for organic compounds. Conclusion: In this study, synergistic- and antagonistic effects in binary mixtures with various concentrationcombinations will provide important information for elucidating the toxicity mechanism of mixtures composed inorganic compounds and metal oxide nanoparticles (MONPs). However, in order to conduct the risk assessment of environmental nanoparticle, further studies regarding the mixture toxicity of nanomaterials with environmentally relevant concentrations and the interaction between components will be required.