Advances on Toxicity and Toxic Mechanisms of Nanomaterials to Aquatic Organisms

An increasing number of nanomaterials with extensive application are discharged into environment. Most nanomaterials released into aquatic environment accumulate in aquatic organisms through food chains and then pose toxic effects to these organisms. Nanomaterials are classified into nano metal oxides, metal nanoparticles, carbon nanomaterials, quantum dots, and organic polymers according to their components. Different sizes, components, and surface modifications of nanomaterials may pose different nanotoxicity and toxic mechanisms to kinds of aquatic organisms. This article reviewed the nanotoxicity and possible toxic mechanisms of nanomaterials to aquatic biological models, such as fish, shellfish, daphnia, and algae. Differences in physical or chemical characteristics can vary nanotoxicity and toxic mechanisms, and it is not clear whether sizes, components, or surface modifications would be critical factors of nanomaterials. The most studied mechanisms are oxidative damage and release of metal ions, while few reports focus on molecular mechanisms such as microarray and epigenetic modifications, which could be a new trend in the future. Therefore, further investigations should concern whether these molecular mechanisms could be used as toxicological evaluation indicators, while taking into consideration of environmental factors which might alter the toxicity of nanomaterials. More studies need to be conducted on toxic mechanisms and risk evaluation of nanomaterials.