Toxic Effects of Micro/Nano Plastics on Soil Animals: Research Progress and Prospectives

Micro/nano plastics (MNPs) is a newly emerging class of pollutant widely distributed in soil. MNPs can affect soil animals and cause ecological toxicity risks. In this paper, an updated review of research progress in this aspect has been conducted. Common soil animals such as earthworms, nematodes, and spring worms can ingest MNPs and affect the distribution of MNPs in soil through digestion and excretion. The toxic effects of MNPs can manifest at various levels, including individual, tissue, and molecular levels, causing effects such as growth and development delays, altered motor behavior, reproduction toxicity and neurotoxicity in soil animals. The toxic effects of MNPs are related to mechanisms such as intestinal injury, metabolic changes, oxidative stress, and abnormal expression of related genes, which may vary depending on the type and size of MNPs. The toxicity of MNPs is also related to the release of plastic additives and other pollutants loaded by MNPs. In addition, soil animals can transmit MNPs to humans by becoming a food or a part of the food chain and cause health risks. Finally, future research directions are outlined.