Potential Radiological Significance of NORM in Marine Sediments from the East Coast of Peninsular Malaysia

This study evaluated the radiological health hazard effects of natural radioactivity (238U, 232Th, and 40K) in marine surface sediments from 20 sampling points along the east coast of Peninsular Malaysia. Samples were collected using a Ponar grab sampler and analyzed via HPGe gamma-ray spectrometry. The radium equivalent activity concentration index (Raeq), absorbed dose rate (Dadr), annual effective dose rate (Daedr), and external hazard index (Hex) were calculated and compared against maximum permissible limits. Results showed all radiological hazard parameters were below regulatory thresholds, with mean Raeq of 80.77 Bq/kg dw. (limit: 370 Bq/kg), mean Dadr of 36.33 nGy/h (world average: 84 nGy/h), mean Daedr of 0.05 mSv/y (world average: 0.07 mSv/y), and mean Hex of 0.22 (limit: 1). Strong positive correlations were observed between 238U and 232Th for all hazard indices, while 40K showed weak correlations, indicating different origin sources. Cluster analysis demonstrated that Dadr, Daedr, and Hex were primarily driven by 238U and 232Th, with 238U identified as a key contributor. The study concluded that sediments pose no significant radiological risks and are suitable for unrestricted use in any activities.