Introduction
Natural and artificial radionuclides are the main sources of human radiation exposure. These radionuclides, which are present in the environment, can enter the food chain. Rice is one of the most important food components in Iran. Radionuclides by transferring from soil to rice and entering the human body can affect human health.
Materials and Methods
Fourteen samples of different varieties of rice, nine soil samples from rice fields and four samples of consumed water were collected from four villages around Gorgan, Iran. Specific activities of ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs were determined in the samples, using gamma ray spectrometry and a high-purity germanium (HPGe) detector. Moreover, transfer factors of radionuclides from soil to rice were determined.
Results
Specific activities of ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs were determined in the soil and rice samples. The annual effective dose due to rice grain consumption in Iranians varied from 20.50±0.74 to 68.40±11.71 µSv/y. Transfer factors from soil to rice for ⁴⁰K and ²²⁶Ra varied from 0.09 to 0.13 and 0.02 to 0.07, respectively.  Conclusion
The calculated annual effective dose due to rice grain consumption by Iranians was within the average annual global range. Therefore, this study indicated that radionuclide intake due to rice consumption had no consequence for public health. The calculated transfer factors were higher than that reported by the International Atomic Energy Agency (IAEA) in 2010; however, the values were much lower than measurements in Malaysia.