Multigenerational growth inhibition and oxidative stress of polystyrene micro(nano)plastics on earthworms (Eisenia fetida)

Micro(nano)plastics (MNPs) are widely detected and persistent in soil ecosystems, posing long-term risks to soil invertebrates. However, the long-term effects of MNPs across generations on soil invertebrates remain unclear. In this study, the effects of polystyrene nanoplastics (PS NPs) and microplastics (PS MPs) at 0.001 %-0.05 % on both parental and offspring earthworms were examined. Compared to control (CK), PS NPs at 0.01 % and 0.05 %, as well as PS MPs at 0.005 %-0.05 % resulted in a decrease in the number of offspring by 34.41 %-39.23 % and 23.60 %-32.15 %, respectively. This suggested a disturbance on the reproduction ability of parents, consistent with the observed seminal vesicle damage. In addition, PS MNPs decreased the growth of parents and offspring by 5.28 %-27.40 % and 28.15 %-43.47 % relative to CK, which could be associated with the observed intestinal damage and oxidative stress. Furthermore, offspring exhibited greater growth inhibition and oxidative stress than their parents, indicating the multigenerational effect of PS MNPs. Metabolomics analysis revealed that PS NPs and PS MPs exposure at 0.05 % inhibited the growth and reproduction of parents via disturbing the membrane transport (ABC transporters), protein translation (aminoacyl-tRNA biosynthesis), and nucleotide metabolism (purine metabolism). Moreover, PS concentration exerted significant effects on individual and biochemical indexes, while particle size induced greater disturbances on the metabolism of parents under the exposure conditions used in this study. Our results highlighted the importance of investigating the long-term effects to comprehensively and accurately assess the ecological risk of MNPs.