Evaluation of excessive lifetime cancer risk due to natural radioactivity in the rivers sediments of Northern Pakistan

Naturally occurring radionuclides 226Ra, 232Th and 40K present in the rivers sediments of Northern Pakistan were measured using HPGe γ-ray spectrometer to evaluate the radiation health hazard indices and excess lifetime cancer risk (ELCR). Average concentrations of 226Ra, 232Th and 40K in the sediments were found to be 50.66 ± 1.29, 70.15 ± 1.45 and 531.70 ± 5.45 Bq kg−1 respectively. Radium equivalent activity (190.89 Bq kg−1), outdoor external dose (87.47 nGy h−1), indoor external dose (165.39 nGy h−1), and total average annual effective dose (0.92 mSv) were calculated. The hazard indices are higher than the world's average values. Total excess lifetime cancer risk (ELCR) was found to be 3.21 × 10−3 which is relatively higher. Numerous cancer deaths are annually reported from the Northern areas of Pakistan, which may be related to high radioactivity in the area.