NATURAL RADIOACTIVITYAND EFFECTIVE DOSE DUE TO THE BOTTOM SEA AND ESTUARIES MARINE ANIMALS IN THE COASTALWATERS AROUND PENINSULAR MALAYSIA M. U. Khandaker*, M. A. Olatunji, K. S. K. Shuib, N. A. Hakimi, N. L. M. Nasir, Kh. Asaduzzaman, Y. M. Amin and H. A. Kassim Department of Physics, University of Malaya, Kuala Lumpur 50603, Malaysia *Corresponding author: mu_khandaker@yahoo.com Malaysia is among the countries with the highest fish consumption in theworld and relies on seafood as a main source of animal protein. Thus, the radioactivity in the mostlyconsumed marine animals such as fishes, crustaceans and molluscs collected from the coastal waters around Peninsular Malaysia has been determined to monitor the level of human exposure by natural radiation via seafood consumption. The mean activity concentrations of naturally occurring radionuclides 226 Ra ( 238 U), 228 Ra ( 232 Th) and 40 K ranged from 0.67 + 0.19 Bq kg 21 (Perna viridis) to 1.20 + 0.70 Bq kg 21 (Rastrelliger), from 0.19 + 0.17 Bq kg 21 (Teuthida) to 0.82 + 0.67 Bq kg 21 (Caridea) and from 34 + 13 Bq kg 21 (Caridea) to 48 + 24 Bq kg 21 (Teuthida), respective- ly. The mean annual committed effective dose due to the individual radionuclides shows an orderof 228 Ra > 226 Ra > 40 K in all marine samples. The obtained doses are less than the global internal dose of 290 mSv y 21 set by the United Nations Scientific Committee on the Effects of Atomic Radiation, discarding any significant radiological risks to the populace of Peninsular Malaysia. INTRODUCTION Besides the presence of natural radioactivity that permeates every compartment of the universe at varying concentrations, human activities such as the release of radioactive wastes from extractive indus- tries, combustion of fossil fuel, production of radionu- clides for medical and industrial applications, offshore oil and gas exploration, operation of power plants, and nuclear accident enhance/cumulate the level of radioactivity in marine environment, hence shows increasing concern to monitor the radionuclide contents in marine materials. Studies of naturally oc- curring radioisotopes of uranium and thorium decay series and primordial potassium in aquatic environ- ment provide information on the environmental pol- lutants in water bodies, whereas marine animals (due to the possible radionuclide transfer) provide an easy assimilation of radiation exposure into human body following their consumption (1) . Moreover, marine organisms such as filter feeders and piscivorous have the capacity of bioaccumulating more radionuclides and toxic elements from water (2) due to the physical and chemical nature of their body surfaces and feeding habit in their natural habitat (3) , and thus, the determination of radioactivity in the bottom sea and estuaries marine animals assumes greater importance. A detailed review of literature (4 – 8) reveals that there is still paucity of data on radionuclide contents in marine materials of Malaysia for adequate radiologic- al assessment to the coastal population. To this end, the study has been conducted to investigate the level of natural radionuclides ( 226 Ra, 228 Ra and 40 K) in mostly consumed marine fishes and shell fishes due to their importance as sources of high-quality protein. The annual effective dose due to intake of radioactiv- ity has been estimated for radiological risk assessment to ensure safer consumption of seafood and other ac- tivities related to the use of marine environment. This study is expected to compliment to the earlier studies on seafood and gives more insights about the nature of marine ecosystem in the country and development of environmental regulatory frameworks. SAMPLING AND SAMPLE PREPARATION Fresh samples of fish (Dasyatidae, Formio niger and Rastrelliger), molluscs (Perna viridis and Teuthida) and crustaceans (Caridea) were collected from both the west and east coasts of Peninsular Malaysia. The choice of these two study areas is due to their bio- diversity and massive fish farming practices. The two coastal areas alone have a total of 59 fish-landing dis- tricts out of 68 landing districts in the country and hence, representing major seafood supply areas to Peninsular Malaysia (9) . The west coast sampling areas such as Pulau Langkawi (Kedah) (lat. 6.35 o N, long. 99.80 o E) and Pantai Remis (Selangor) (lat. 4.45 o N, long. 100.63 o E) located at the coast of the Strait of Malacca are known for many industrial activities, particularly release of industrial effluent from various extractive industries. The other two locations Tok Bali (Kelantan) (lat. 5.89 o N, long. 102.48 o E) and Tanjung Lumpur (Kuantan) (lat. 3.80 o N, long. 103.04 o E) laid in the east coast facing out to the # The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com Radiation Protection Dosimetry (2015), pp. 1–5 doi:10.1093/rpd/ncv243 Radiation Protection Dosimetry Advance Access published May 8, 2015 at Universiti Malaya on May 10, 2015 http://rpd.oxfordjournals.org/ Downloaded from