Phytotoxicity of CeO₂ nanoparticles on radish plant (Raphanus sativus)

Cerium oxide nanoparticles (CeO₂ NPs) have been considered as one type of emerging contaminants that pose great potential risks to the environment and human health. The effect of CeO₂ NPs on plant-edible parts and health evaluation remains is necessary and urgently to be developed. In this study, we cultivated radish in Sigma CeO₂ NP (<25 nm)-amended soils across a series of concentration treatments, i.e., 0 mg/kg as the control and 10, 50, and 100 mg/kg CeO₂ NPs. The results showed that CeO₂ NPs accelerated the fresh biomass accumulation of radish plant; especially in the treatment of 50 mg/kg CeO₂ NPs, root expansion was increased by 2.2 times as much as the control. In addition, the relative chlorophyll content enhanced by 12.5, 12.9, and 12.2% was compared to control on 40 cultivation days. CeO₂ NPs were mainly absorbed by the root and improved the activity of antioxidant enzyme system to scavenge the damage of free radicals in radish root and leaf. In addition, this study also indicated that the nanoparticles might enter the food chain through the soil into the edible part of the plant, which will be a potential threat to human health.