Abstract: Objective In order to know the levels of radionuclides in corn and rice in the studied area, and their annual effective dose to the local residents caused by different crops, so as to provide a scientific basis for improving food safety and protecting people’s health. Methods According to the methods specified in the national standards, the three natural radionuclides of ²³⁸U, ²²⁶Ra, and ²³²Th were measured in 30 corn and rice samples, and the results were processed and analyzed. Results The average activity concentrations of ²³⁸U, ²²⁶Ra, and ²³²Th in corn were 0.003 5, 0.063, and 0.004 Bq/kg respectively; the average activity concentrations of ²³⁸U, ²²⁶Ra, and ²³²Th in rice were 0.108 8, 0.751, and 0.135 Bq/kg respectively. Conclusion Rice is easier to accumulate natural radionuclides than corn. Activity concentration of radioactive substances in corn and rice samples in the studied area is much lower than the limit specified in the national standard and the world average. The internal radiation dose of residents caused by ingestion is much lower than the personal dose guidelines for food-induced exposure under existing exposure conditions, and it will not affect the health of residents after ingestion.

Key words: Radionuclide content, Corn, Rice, Annual effective dose, Shizuishan, Ningxia