Acute toxicities of six manufactured nanomaterial suspensions to Daphnia magna

The rapid growth of nanotechnology is stimulating research on the potential environmental impacts of manufactured nanomaterials (MNMs). This paper summarizes a comprehensive study on the 48-h acute toxicity of water suspensions of six MNMs (i.e., ZnO, TiO₂, Al₂O₃, C₆₀, SWCNTs, and MWCNTs) to Daphnia magna, using immobilization and mortality as toxicological endpoints. The results show that the acute toxicities of all MNMs tested are dose dependent. The EC₅₀ values for immobilization ranged from 0.622 mg/L (ZnO NPs) to 114.357 mg/L (Al₂O₃ NPs), while the LC₅₀ values for mortality ranged from 1.511 mg/L (ZnO NPs) to 162.392 mg/L (Al₂O₃ NPs). In these tests, TiO₂, Al₂O₃, and carbon-based nanomaterials were more toxic than their bulk counterparts. Moreover, D. magna were found to ingest nanomaterials from the test solutions through feeding behaviors, which indicates that the potential ecotoxicities and environmental health effects of these MNMs cannot be neglected.