Radionuclide intake due to food drying surfaces: implications for individual ingestion effective dose in Ogbomoso, Southwestern Nigeria

Abstract

Measurement of low-level radionuclide transfer from food drying surfaces is of radiological importance in environmental protection, especially in West Africa where farmers commonly preserve their foodstuffs by a low cost method of sun-drying on surfaces such as rock, asphalt, concrete, wood, metals, or roofing sheets which are reported sources of natural radionuclides. The transfer coefficient of natural radionuclides from drying surfaces into food samples is therefore a concern for dietary intake for the consumers. The radioactivity measurements of commonly used food drying surfaces in Ogbomoso, as well as cassava flour sun-dried on these surfaces were performed via gamma-ray spectrometry. Cassava flour was sun-dried on fabric raised 1 meter above the ground to serve as control sample (CF control ). Activity concentrations of 40 K, 238 U, 232 Th in rock, asphalt, concrete and cassava flour dried on these surfaces were determined using a lead-shielded NaI(Ti) detector crystal. Food consumption data and the measured activity concentrations in dried cassava flour were used to estimate ingestion effective dose of radionuclide intake from cassava flour due to these drying surfaces. Annual ingestion effective doses (mSvy−1) in cassava flour dried on concrete, rock, asphalt and fabric were estimated to be 0.72, 0.59, 0.42 and 0.26, respectively. Radionuclide addition was observed in cassava flour dried on concrete, rock and asphalt with transfer variation maximum in rock surface and minimum in asphalt surface. Result of this study is useful for radiometric data analysis in the study area especially on food safety regulations.