Assessment of Natural Radionuclide Contents in Local and Imported Rice Sold in Tamale Metropolis And their Health Effects On Consumers.

Abstract

This study determined the concentrations of natural radionuclides in locally grown and imported rice sold in Tamale metropolis using gamma ray spectrometry with a High Purity Germanium (HPGe) Detector. Eight samples (four local and four imported samples) were bought from Tamale Central and Aboabo markets and used for the analysis. In the local rice, the mean activity concentrations of Ra-226, Th-228, Ra-228, Th-232 and K-40 were 2.5 ± 0.19, 0.7 ± 0.08, 3.8 ±0.40, 4.28 ± 0.34 and 49.73 ± 3.99 Bq/kg respectively, while in the imported rice, the mean activity concentrations were 2.13 ±0.23, 1.28 ± 0.09, 4.2 ± 0.34, 1.7 ± 0.11 and 27.33 ± 2.24 Bq/kg respectively. These levels were below World average values as per UNSCEAR (2000). Comparison of the concentrations of radionuclides detected in the local and imported rice samples showed that there were no significant differences in their mean concentrations. The mean values of external and internal hazard indices for local rice were 0.0336 and 0.0404 respectively while those for imported rice were 0.0180 and 0.0237 respectively. The mean values were below unity. These indicate that the rice samples (both local and imported) are not hazardous to consumers. The mean values of Excess Lifetime Cancer Risk for the local and imported rice samples were 0.0295 x 10-3 and 0.0160 x 10-3 respectively. These values are below the world average value of 0.29 × 10−3. The results suggest that both local and imported rice sold in Tamale metropolis are radiologically safe for consumers. Continuous monitoring in each production season, similar studies in rice produced in other parts of the country and similar studies in tuber crops were recommended.