Natural radioactivity measurements in Pahang State, Malaysia

This study was aimed at providing the baseline data of terrestrial gamma dose rates and natural radioactivity to assess the corresponding health risk in the ambient environment of the Pahang State. Terrestrial gamma radiation (TGR) from 640 locations was measured with the mean value found to be 176 +/- 5 nGy h(-1). Ninety-eight soil samples were analysed using a high-purity germanium detector (HPGe), and the mean concentrations of the radionuclides Ra-226, Th-232 and K-40 are 110 +/- 3, 151 +/- 5 and 542 +/- 51 Bq kg(-1), respectively.Ra-226 and Th-232 concentrations were found to be three times the world average, while that of K-40 is quite higher than the world average value. The acid-intrusive geological formation has the highest mean concentrations for Ra-226 (215 +/- 6 Bq kg(-1)), Th-232 (384 +/- 12 Bq kg(-1)) and K-40 (1564 +/- 153 Bq kg(-1)). The radium equivalent activities (Req) and the external hazard index (Hex) for the various soil types were also calculated. Some of the soil types were found to have values exceeding the internationally recommended levels of 370 Bq kg(-1) and the unity value, respectively.