Invisible Invaders: Ecotoxicological Impacts of Nano‐ and Microplastics in Aquatic Ecosystems

Abstract Nano‐ and microplastics (NMPs) are increasingly recognized as enduring pollutants in aquatic environments, eliciting heightened ecotoxicological apprehensions. Their diminutive size, extensive surface area, and chemically varied composition—frequently augmented with additions, residual monomers, and adsorbed contaminants—improve bioavailability, cellular absorption, and trophic transfer, thereby heightening ecological concerns. This review synthesizes existing research about the origins, environmental alterations, and toxicological mechanisms of NMPs in freshwater ecosystems, emphasizing their interactions with co‐contaminants including heavy metals, pharmaceuticals, and persistent organic pollutants. These combinations often exacerbate toxicity via vector effects and synergistic processes. Comparisons with manufactured nanoparticles (NPs) underscore both common toxicological issues and unique risks associated with NMPs. The limitations of current ecotoxicological assessment tools are critically explored, originally designed for dissolved pollutants, and examine recent developments in detection methodologies, experimental models, and environmental monitoring strategies. The study delineates critical goals for mechanistic investigations that connect molecular‐level responses with ecosystem‐scale effects, as well as the advancement of enhanced diagnostic tools and regulatory frameworks. The review identifies strategies to enhance the evaluation and reduction of the increasing ecological risk posed by NMPs in aquatic ecosystems.