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

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 (ECx_mix) 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. [ABSTRACT FROM AUTHOR]