Nanoplastics toxicity in aquatic organisms: a review of effects on selected marine and freshwater species

Nanoplastics (NPs), particles smaller than 1 μm, are considered a significant threat to aquatic ecosystems due to their ability to penetrate tissues, bioaccumulate, and disrupt physiological functions. However, quantitative data on their chronic and environmentally relevant effects remain limited. This review combines findings from 128 studies (2014-2025) on the effects of nanoparticles in five representative freshwater and marine species: <i>Scenedesmus obliquus</i> (microalgae), <i>Crassostrea gigas</i> (bivalve), <i>Apostichopus japonicus</i> (echinoderm), <i>Litopenaeus vannamei</i> (crustacean), and <i>Danio rerio</i> (fish). Our analysis shows that exposure to NPs at low concentrations of 0.1-100 μg/mL can cause oxidative stress, membrane damage, developmental disorders, reproductive changes, and immune and nervous system dysfunction. Factors affecting the toxicity of NPs include particle size, concentration, type, and aging status, as well as duration of exposure, organism sensitivity, environmental conditions, and the presence of co-contaminants. Despite the increasing recognition of the effects of nanoplastics, quantitative data on their chronic and long-term effects, particularly at environmentally relevant exposure levels, remain scarce. This review highlights the urgent need for future research focusing on the mechanisms and processes of nanoparticle toxicity at ecologically realistic concentrations, as well as on the long-term ecological and physiological consequences for aquatic organisms.