THE NATURAL RADIOACTIVITY IN SOME NIGERIAN FOODSTUFFS

The average activity concentrations of seven locally produced food commodities that form the total diets of a baby, a teenager or an adult male in Nigeria were measured by means of a well-calibrated high-resolution lithium-drifted germanium (Ge(Li)) spectrometer system. The food commodities were collected at several centers such as a nuclear research center as well as metropolitan and industrial areas. The emission lines identified with reliable regularity belonged to the U-238 and Th-232 decay series. The other isotope is a non-related naturally occurring radionuclide, K-40. Average total specific-activity values of 7.29 +/- 1.08, 6.27 +/- 1.01 and 11.23 +/- 1.64 Bq/kg for U-238, Th-232 and K-40, respectively, were obtained for the seven food commodities studied. The food samples were also checked for fission-product residues (Cs-137 and Sr-90) from atmospheric weapons tests which are slowly being purged from the food chain. Their estimation revealed that they were below the minimum detectable limit determined at a two-standard deviation analytical error.