Uptake, Biodistribution, and Mechanisms of Toxicity of Metal-Containing Nanoparticles in Aquatic Invertebrates and Vertebrates

The increasing production and use of nanoparticles (NPs) have raised concerns with regard to their environmental accumulation and toxicity in nontarget organisms. Aquatic ecosystems receive high inputs of nanopollutants from riverine and terrestrial sources, and thus aquatic organisms are potentially vulnerable to the off-target toxic effects of nanoparticles. The reactivity and the toxicological profile of the metal-based NPs strongly depend on their physicochemical properties, including the particle size, shape, surface area, surface charge and coating, aggregation, dissolution, and protein corona effects. This chapter focuses on nano-ZnO as model nanopollutants with high production volume, broad use, and relatively well-studied toxicity, and summarizes the current state of knowledge about the toxic effects of nanoparticles and their mechanisms in aquatic invertebrates and lower vertebrates. We discussed the mechanisms of uptake and accumulation of Zn and ZnO in aquatic organisms and considered the ZnO-specific toxic mechanisms (related to the release of ionic Zn) as well as the toxic mechanisms shared between nano-ZnO and other nanoparticles such as redox activity, immunotoxicity and cytotoxicity reflected in the oxidative stress, lysosomal and mitochondrial damage, inflammation, and programmed cell death. We also identified the existing gaps in our knowledge with regard to the toxicity and environmental risk assessment of the nanopollutants including nano-ZnO and discussed possible research approaches to close these gaps.