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To investigate the pollution caused by microplastics (MPs) in agricultural systems and their possible mechanisms of action, the distribution characteristics of MPs in the surface soils of 56 sites in paddy fields of three towns in Xiangtan City, Hunan Province, China, were determined. Fourteen sites were randomly selected to collect rice grains after harvest. The effect of MPs on the migration of bisphenol A (BPA) and cadmium (Cd) from soil to rice grains were analyzed. Four forms of aging MPs were detected in soils：films, particles, fragments, and fibers. The abundance of MPs in the three towns was similar, ranging from 48 items·kg-1 to 1 771 items·kg-1 ; the main components were polyethylene (PE) and polyvinyl chloride (PVC), accounting for 46.77% and 24.19%, respectively, and the content of polycarbonate (PC) was significantly lower than that of ethylene terephthalate (PET) (2.51 μg·kg-1 and 113.35 μg·kg-1, respectively) . BPA in depolymerized soils showed a more significant positive correlation with the content of BPA in rice grains than in un-depolymerized soils (P<0.01), indicating a potential risk of secondary release of BPA during the aging of MPs in the environment. In addition, the Cd content in soils also exhibited a significant positive correlation (P<0.001) with the abundance of MPs, promoting the transformation of Cd from soils to rice grains. This study contributes to the overall and objective evaluation of the pollution and health risks posed by MPs in agricultural systems. [ABSTRACT FROM AUTHOR]