Radioactivity and radiological risk associated with effluent sediment containing technologically enhanced naturally occurring radioactive materials in amang (tin tailings) processing industry Ismail Bahari * , Nasirian Mohsen, Pauzi Abdullah Nuclear Science Programme, Faculty of Science and Technology, National University of Malaysia, Bangi, 43600 Selangor, Malaysia Received 1 September 2006; received in revised form 12 February 2007; accepted 12 February 2007 Available online 10 April 2007 Abstract The processing of amang, or tin tailings, for valuable minerals has been shown to technologically enhance NORM and this has stirred significant radiological safety and health concerns among Malaysia’s regulatory authority. A growing radiological concern is now focused on the amang effluent containing NORM in recycling ponds, since these ponds may be reclaimed for future residential developments. A study was carried out to assess the radiological risk associated with amang processing and the accumulated effluent in the recycling ponds. Twenty-six sediment samples from the recycling ponds of two amang plants in the states of Selangor and Perak, Malaysia, were collected and analyzed. The maximum activity concen- trations of 238 U, 226 Ra, 232 Th and 40 K recorded in sediments from these ponds were higher than Malaysia’s and the world’s natural highest. Correspondingly, the mean radium equivalent activity concentration indi- ces, Ra eq , and gamma radiation representative level index, I gr , were higher than the world’s average. The enhancement of NORM in effluent sediments as a consequence of amang processing, and the use of a closed water management recycling system created Effective Dose Rates, E (nSv h 1 ), that signal potential envi- ronmental radiological risks in these ponds, should they be reclaimed for future land use. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: NORM; Amang; Sediment; Recycling pond; Radiological risk * Corresponding author. Bangunan Sains Nuklear, Fakulti Sains & Teknologi, Universiti Kebangsaan Malaysia, 43600 Selangor, Malaysia. Tel./fax: þ60 389215478. E-mail address: ismailb@pkrisc.cc.ukm.my (I. Bahari). 0265-931X/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.jenvrad.2007.02.009 Journal of Environmental Radioactivity 95 (2007) 161e170 www.elsevier.com/locate/jenvrad