Transfer factors of some radionuclides from soil to rice and annual absorbed dose due to consuming of two types of rice (Hashemi, Khazar) in the north of Iran (Siyahkal city- Gilan Province)

In this study, due to radionuclidic uptake evaluation by rice variety (Hashemi & Khazar types) in Gilan province-Siyahkal city and annual effective dose determination for the use of these two types of rice, 16 rice genotype samples and 16 samples from the related paddy soils were collected. After the sample preparation, the type of radionuclides and their specific activities were determined for each sample by the method of gamma spectrometry. Finally, the transfer factor and annual effective dose, due to the use of these two types of rice, were calculated via the related formulas. The soil of the area contained actinium-228 (228Ac), bismuth-214 (214Bi), cesium-137 (137Cs), lead-214 (214Pb), thallium-208 (208Tl), and potassium-40 (40K) with the average activities of 49.96, 47.73, 23.09, 50.63, 18.00 and 711.30 Bq/kg, respectively. The rice seeds contained only 40K as a natural radioactive element with the average specific activities of 128.23 and 138.28 Bq/kg for Hashemi and Khazar types, respectively. The average transfer factor of 40K from soil to rice was 0.19 for the Hashemi type and 0.21 for Khazar type. This factor for the both types of rice was approximately the same. Also, the annual effective dose for consuming these two types of rice was 0.031 and 0.034 mSv/year for Hashemi and Khazar types, respectively. The annual effective dose is much lower than the standard permissible limit (1 mSv/year). Therefore, from this point of view, the use of these two types of rice will not threaten the health of the consumers.