Abstract: The increases in plastic production and inadequate plastic waste management have significantly increased the presence of microplastics (MPs) in the environment. MPs refer to plastic fragments and particles with a size smaller than 5 millimeters. Numerous studies have focused on the impacts of MPs on the environment and living organisms, and explored the potential mechanisms. Humans and other organisms can ingest or carry MPs through various pathways, which have a range of adverse effects on metabolism, functionality, and health. Additionally, due to their larger surface area, MPs could adsorb various pollutants, including heavy metals and persistent organic pollutants, severely affecting the health of animals and humans. Based on research on MPs in recent years, we reviewed the sources and distribution of MPs, examined exposure pathways, toxic effects, and toxicological mechanisms on plants, animals, and human bodies, and provided a prospective outlook on future directions for MP research. This review would be a reference for further assessments of the health risks of MPs.

Key words: microplastics, source and distribution, biological accumulation, toxic effect, stress of plants, animal and human health