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 measued 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 238U and 232Th decay series. The other isotope is a non-related naturally occurring radionuclide, 40K. Average total specific-activity values of 7.29±1.08, 6.27±1.01 and 11.23±1.64 Bq/kg for 238U, 232Th and 40K, respectively, were obtained for the seven food commodities studied. The food samples were also checked for fission-product residues (137Cs and 90Sr) 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. (orig.)