Acute Toxicity of Suspension of Nanosized Silicon Dioxide Particles to Daphnia Magna

There is a broad application area for engineering nanoparticles (ENPs) in virtue of its special physical and chemical properties. ENPs bring a huge advance to development of human society, as well as the questions about whether the manufactured nanomaterials (MNMs) can cause disadvantages to organisms and environment. This paper analyzed the 24-h acute toxicity of water suspensions of the nanosized silicon dioxide (Nano-SiO₂) and the normal sized silicon dioxide (Nor-SiO₂) as its bulk counterpart to Daphnia magna with different concentration. The experiment considered EC₅₀ value for immobilization and LC₅₀ value for mortality as the toxicological test targets. The results show that the toxicity of Nano-SiO₂ is obviously does-dependent but the Nor-SiO₂ is not, evidently. The optical microscope and digital camera also been used to observe and record the biological form of Daphnia magna during the exposure and in this study we found that D. magna can uptake and adsorb Nano-SiO₂ but only apparently show uptaking to its bulk counterpart. The conclusions of results suggest that there is potential harm to aquatic environment in using Nano-SiO₂, and it should deserve special concern.