Abstract:
The exposure of man to naturally-occurring radionuclides through food and water intake gives rise to a dose which varies depending on the location, diet and habit of the individuals concerned. Potassium-40 (40K), Thorium-232 (232Th) and Uranium-238 (238U) are the common naturally occurring radionuclides present in soil and can therefore be found in foodstuff due to nutrient uptake from the soil.
The activity concentrations of 40K, 232Th and 238U were determined in 37 mushroom samples collected from 5 selected Local Government Areas (LGA) across Ondo State which include; Akure-South, Idanre, Ifedore, Ile-Oluji/Okeigbo and Okitipupa. The samples were prepared for analysis according to the International Atomic Energy Agency (IAEA) procedures Samples were analyzed at the Centre for Energy Research and Development, Obafemi Awolowo University, Ile Ife, Osun State, using gamma ray spectrometry technique. The analysis was done using NaI (Tl) scintillation detector (Canberra Industries Inc.). Potassium-40 was found to have the highest activity concentration in all the mushroom samples.
The levels of 40K varied from 1939.56 ± 213.65 to 69.42 ± 19.08 Bq kg-1, 232Th levels varied from 19.94 ± 4.30 to 6.02 ± 2.84 Bq kg-1 and 238U levels varied from 29.75 ± 6.89 to 9.01 ± 4.92 Bq kg1. Annual effective dose to individuals was estimated to be 12.227 µSv y-1. The mean annual effective dose to individual from the consumption of mushroom in Ondo State is 0.330 µSv y-1. These values are below the 1 mSv y-1 recommended by International Commission on Radiological Protection (ICRP) for the general public. The results of this study therefore give an indication that mushroom consumption does not pose any risk to the health of the populace.
