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 (SnO2 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 (SnCl4). Based on the actual concentration of Sn, SnO2 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, SnO2 NP suspensions were found to exhibit limited acute toxicity in D. magna and D. rerio. Moreover, the toxicity of the SnO2 NP suspension was lower than SnCl4 for all three trophic aquatic organisms. Comparison of component-specific contribution to overall toxicity indicated that, in SnO2 NP suspensions, particulate Sn more significantly contributed to toxicity than dissolved Sn-ions. Furthermore, we found that the toxic mechanism of the SnO2 NP suspension involved the induction of oxidative stress by increasing intracellular ROS accumulation.