Comparative Acute Toxicity and Oxidative Stress Responses in Three Aquatic Species Exposed to Stannic Oxide Nanoparticles and Stannic Chloride

We experimentally investigated the toxicity of stannic oxide nanoparticles (SnO 2 NPs) to three freshwater species including Scenedesmus obliquus , Daphnia magna , and Danio rerio . To evaluate effect, toxicological impacts were compared to that of stannic chloride (SnCl 4 ). Based on the actual concentration of Sn, SnO 2 NPs suspensions inhibited growth of S. obliquus in a dose-dependent manner, demonstrating a median effect concentration of 2.28 ± 0.53 mg/L. However, SnO 2 NP suspensions were found to exhibit limited acute toxicity in D. magna and D. rerio . Moreover, the toxicity of the SnO 2 NP suspension was lower than SnCl 4 for all three trophic aquatic organisms. Comparison of component-specific contribution to overall toxicity indicated that, in SnO 2 NP suspensions, particulate Sn more significantly contributed to toxicity than dissolved Sn-ions. Furthermore, we found that the toxic mechanism of the SnO 2 NP suspension involved the induction of oxidative stress by increasing intracellular ROS accumulation.