Evaluation of Radioactivity Contents and Excess Lifetime Cancer Risk Due to Ingestion from Natural Radionuclides in Maize Samples from Some Selected Maize Farms in Ekiti State, Nigeria

Abstract

The study was carried out to evaluate the radioactivity concentrations of 40K, 232Th and 238U in five maize samples collected from maize farms within Ekiti State, Nigeria. The activity concentration measurements were determined using n – type co-axial HPGe detectors for the state. The activity concentrations were found to vary from 994.67 – 2457.01 Bq Kg-1 for 40K, 32.84 – 91.88 Bq kg-1 for 232Th and 43.21 – 97.77 Bq kg-1 for 238U respectively. The annual effective dose to individuals from the consumption of the Maize was estimated on the basis of the measured radionuclides content in the food crop which ranged between 0.41 and 1.51 m Svy-1 respectively. The value1.04 m Svy-1 were obtained for the state as the mean total annual effective dose. The mean excess life time cancer risk was also calculated to be 2.06x10-9 . The value was compared with the internationally acceptable limits and found to be far less to the maximum permissible dose of 1.0 x10-3 recommended for the public by the United Nations Scientific Committee on the Effects of Atomic Radiation. Hence, the maize was found to be safe for human consumption.