The Potential for Toxicity to Fishes from Micro- and Nanoplastics, and Their Additives

Over the past several decades, the intense production and use of plastics have led to the contamination of all types of ecosystems with microplastics. Microplastics, plastic particles less than 5 mm in size, and nanoplastics which are less than 1 μm, are a diverse contaminant suite comprised of different sizes, shapes, polymer properties, additives and sorbed pollutants, and biofilms. Micro and nanoplastics (MNPs) may pose a potential danger for organisms who are exposed to the particles and the chemicals associated with the plastics. As many marine and freshwater systems are highly contaminated with MNPs, fish are continuously exposed to them, which may lead to a variety of adverse effects. This chapter describes current knowledge on the relationship between nano- and microplastic occurrence in freshwater and marine ecosystems and the potential toxicological effects in fish. First, the MNP properties, associated additives, pollutants, and biofilms are described. Following, it is illustrated how fish can be exposed to MNPs and which adverse effects exposure can have on the different levels of biological organization of fish. These effects range from altered gene expression, oxidative stress, and immune responses to changes in behavior and impaired reproduction. Finally, new multivariate approaches to address microplastic toxicity and recommended future research directions are summarized.