Schirmer, K. (2014). Mechanisms of Nanotoxicity. In J. R. Lead & E. Valsami-Jones (Eds.), Frontiers of Nanoscience: Vol. 7. Nanoscience and the Environment (pp. 195-221). https://doi.org/10.1016/B978-0-08-099408-6.00006-2
When nanomaterials reach environmental compartments, such as freshwater or soil, interaction with organisms living in those compartments is likely to occur. It therefore is important to understand how nanomaterials and organisms interact, and to develop mechanism-based frameworks that allow transfer of knowledge across particle types and biota with justifiable effort to provide a sound risk assessment. First encounter of nanomaterials with organisms always takes place at the level of cells, for example, epithelial cells in animals or epidermal cells in plants, which serve as environment–organism barriers. Being evolutionarily exposed to inorganic or organic particles, cells have evolved stress responses to combat particle exposure but if overwhelmed, toxicity on different cellular levels, such as damage to lysosomes, mitochondria, or DNA may ensue. However, even in the absence of toxicity, nanomaterials may surpass environment–organism barriers. In this case, systemic distribution may occur, potentially triggering whole organism responses, such as immune or altered behavioral responses or contorted development. Finally, whole organism responses may impact on population and ecosystem network interactions. Two examples are impacts on symbiotic interactions or on communication within the same and between different species. Taking such a systems-view approach, from the subcellular to the ecosystem level, I here provide an overview of the mechanistic knowledge in environmental nanotoxicology available thus far. Indeed, we are at the verge of moving from description to mechanistic understanding of nanotoxicity in organisms living in different environments. Advancement in this area, however, strongly depends on rigorous nanomaterial characterization and thus on embracing physical and chemical science to provide the best possible link between particle characteristics, concentrations occurring in the environment and mechanisms of stress response and toxicity.