Committed effective dose from naturally occuring radionuclides in shellfish Mayeen Uddin Khandaker a,n , Norfadira Binti Wahib a , Yusoff Mohd. Amin a , D.A. Bradley a,b a Department of Physics, University of Malaya, 50603 Kuala Lumpur, Malaysia b Department of Physics, University of Surrey, Guildford, GU2 7XH, United Kingdom HIGHLIGHTS c Activity concentrations of naturally occuring radionuclides were assessed for shellfish. c 238 U, 232 Th, 40 K intake via shellfish showed several times higher than world averages. c Committed effective doses due to the ingestions of 238 U, 232 Th, 40 K are the first report in Malaysia. c Estimated committed effective dose also showed higher values than the world average. article info Article history: Received 26 December 2012 Accepted 26 February 2013 Available online 7 March 2013 Keywords: Shellfish Naturally occuring radionuclides Activity concentrations Radium equivalent activity Estimated daily intake Committed effective dose 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 g-ray spectrometer. For molluscs, assuming secular equilibrium, the range of activities of 238 U ( 226 Ra), 232 Th ( 228 Ra) and 40 K were found to be 3.28 70.35 to 5.34 70.52, 1.20 70.21 to 2.44 70.21 and 118 76 to 281 714 Bq kg 1 dry weight, respectively. The respective values for crustaceans were 3.02 70.57 to 4.70 70.52, 1.38 70.21 to 2.40 70.35 and 216 711 to 316 715 Bq kg 1 . The estimated average daily intake of radioactivity from consumption of molluscs are 0.37 Bq kg 1 for 238 U( 226 Ra), 0.16 Bq kg 1 for 232 Th ( 228 Ra) and 18 Bq kg 1 for 40 K; the respective daily intake values from crustaceans are 0.36 Bq kg 1 , 0.16 Bq kg 1 and 23 Bq kg 1 . Associated annual committed effective doses from molluscs are estimated to be in the range 21.3 to 34.7 mSv for 226 Ra, 19.3 to 39.1 mSv for 228 Ra and 17.0 to 40.4 mSv for 40 K. For crustaceans, the respective dose ranges are 19.6 to 30.5 mSv, 22.0 to 38.4 mSv and 31.1 to 45.5 mSv, being some several times world average values. & 2013 Elsevier Ltd. All rights reserved. 1. Introduction Naturally occuring radioactivity is ubiquitous in terrestrial media (UNSCEAR, 2000a), leading to continuous exposure of human populations to naturally occuring radioactive material (NORM) and potential health effects (see for instance UNSCEAR, 1982a). However, given that the health effects of natural levels of radioactivitiy within the environment are not completely under- stood, it is the general internationally accepted principle that additional exposures to ionizing radiations should be kept to as low as reasonably achieveable (ALARA), a recommendation of the International Commission for Radiological Protection (ICRP). Thus of related concern are the potentially enhanced levels of natural radioactivity that inadvertently result from industrial non nuclear fuel cycle activities, termed technologically enhanced naturally occuring radioactive material (TENORM). Depending upon habit and circumstances, cumulative long term exposure to TENORM could lead to deleterious health effects, the decay products of 238 U and 232 Th being predominantly alpha emitters, the major source of internal exposures. As an example, while typically existing at very low levels in pristine environments, the radium decay sub- series 226 Ra- 222 Rn- 214 Bi- 210 Pb- 210 Po within the 238 U decay chain are certainly found in most abiotic and biotic materials, leading to direct and indirect human radiation exposures. Chronic exposure to TENORM will undoubtedly increase absorbed dose, from below detectable levels that challenge the ability to measure the additional dose, through to levels that can be measured. In the present paper, we examine a particular example of the latter. Due to the radiotoxicity and associated health risks of 226 Ra and progeny within the 238 U decay chain and 228 Ra and progeny within the 232 Th decay chain, determination of their presence in edible Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/radphyschem Radiation Physics and Chemistry 0969-806X/$ - see front matter & 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.radphyschem.2013.02.034 n Corresponding author. Tel.: þ601115402880; fax: þ60379674146. E-mail addresses: mu_khandaker@yahoo.com, mu_khandaker@um.edu.my (M.U. Khandaker). Radiation Physics and Chemistry 88 (2013) 1–6