Committed effective dose from naturally occuring radionuclides in shellfish

Abstract

Recognizing their importance in the average Malaysian daily diet, the radioactivity concentrations in mollusc- and crustacean-based food have been determined for key naturally occuring radionuclides. Fresh samples collected from various maritime locations around peninsular Malaysia have been processed using standard procedures; the radionuclide concentrations being determined using an HPGe γ-ray spectrometer. For molluscs, assuming secular equilibrium, the range of activities of 238U (226Ra), 232Th (228Ra) and 40K were found to be 3.28±0.35 to 5.34±0.52, 1.20±0.21 to 2.44±0.21 and 118±6 to 281±14Bqkg−1 dry weight, respectively. The respective values for crustaceans were 3.02±0.57 to 4.70±0.52, 1.38±0.21 to 2.40±0.35 and 216±11 to 316±15Bqkg−1. The estimated average daily intake of radioactivity from consumption of molluscs are 0.37Bqkg−1 for 238U (226Ra), 0.16Bqkg−1 for 232Th (228Ra) and 18Bqkg−1 for 40K; the respective daily intake values from crustaceans are 0.36Bqkg−1, 0.16Bqkg−1 and 23Bqkg−1. Associated annual committed effective doses from molluscs are estimated to be in the range 21.3 to 34.7μSv for 226Ra, 19.3 to 39.1μSv for 228Ra and 17.0 to 40.4μSv for 40K. For crustaceans, the respective dose ranges are 19.6 to 30.5μSv, 22.0 to 38.4μSv and 31.1 to 45.5μSv, being some several times world average values.