Annual intakes of 226Ra, 228Ra and 40K in staple foodstuff's from a high background radiation area in the southwest region of Cameroon

Concentrations of naturally occurring radionuclides Ra-226, Ra-228 and K-40 were determined in five most consumed vegetables in a high-level background radiation area (HLBRA) in the southwest region of Cameroon. A total of 25 foodstuff samples collected from Akongo, Ngombas, Awanda, Bikoue and Lolodorf rural districts were analyzed by gamma spectrometry. The average activity concentration values of Ra-226, Ra-228 and K-40 were respectively 2.30, 1.50 and 140.40 Bq kg(-1) fresh-weights. The effective dose for individual consumption of the investigated foodstuff types was calculated on an estimated annual intake of such diets in the study area. The estimated total daily effective doses from the ingestion of the investigated foodstuffs for each studied long-life natural radionuclide were respectively 0.41 mu Sv for Ra-226, 0.84 mu Sv for Ra-228 and 0.71 mu Sv for K-40. The total annual effective dose was estimated at 0.70 mSv y (-1). Ra-228 (44%) and K-40 (36%) were found to be the main sources for internal irradiation which is very likely due to the specific uptake of these radionuclides by the studied plants. (C) 2012 Elsevier Ltd. All rights reserved.