Accumulation and toxic effects of polystyrene nanoplastics in Pale chub (Zacco platypus)

Abstract

The effects of plastic contaminants in freshwater on the environment have continually raised concerns owing to their potential ecotoxicology. Monitoring and regulating the toxic effects of nanoplastics (NPs) are challenging owing to the lack of studies comparing nanoscale plastics to microscale plastics in freshwater aquatic organisms. Hence, this study conducted accumulation and toxicity tests in aquatic organisms using 50 nm polystyrene NPs (PS-NPs). Pale chub (Zacco platypus) was used as test organism in this study, as it is a dominant species in Korean freshwater ecosystem and has a wide longitudinal distribution range, being found both upstream and downstream in all Korean watersheds. In this study, pale chubs were exposed to two concentrations of PS-NPs via a culture medium. The accumulation of PS-NPs, swimming behavior, enzymatic activities, and histopathological changes in each tissue were monitored; PS-NPs were quantified via pyrolysis gas chromatography-mass spectrometry. PS-NPs were found in all tissues of brain, branchiae, heart, liver, spleen, digestive tract, and air bladder of pale chub after 14 days of exposure. PS-NPs induced an increase in enzymatic activity, indicating that oxidative stress was generated because of NP exposure. In addition, the analysis of swimming behavior suggested that NP exposure decreased the maximum speed and total swimming distance of pale chub. Histopathological changes in the brain suggest that the NPs accumulated in the brain affected fish behavior. This study presents a new perspective on the quantification of NPs and their toxic effects on fish.