Hazard of NORM from phosphorite of Pakistan.

In order to investigate the radiological hazard of naturally occurring radioactive material (NORM) in phosphorite deposits of Pakistan, 26 samples of phosphorite were collected from the phosphorite mines near Abbottabad, and 20 samples of single superphosphate (SSP) fertilizer were obtained from the warehouses in Pakistan. Activity concentration in all the samples was assayed using HPGe detection system. Specific activity values of (238)U, (40)K, (226)Ra and (232)Th in the samples of phosphorite were 550+/-156 (329-845), 206+/-72 (93-362), 511+/-189 (316-830) and 52+/-17 (23-81) Bq kg(-1), respectively; and those in SSP fertilizer due to these radionuclides were 637+/-44 (596-687), 164+/-24 (113-215), 589+/-44 (521-671) and 29+/-6 (16-45) Bq kg(-1), respectively. The results were compared with that of worldwide soil. Outdoor external dose rate due to gamma rays from phosphorite was calculated to be 276+/-94 (177-441) nGy h(-1) and external dose rate in a room made of phosphorite containing material was estimated to be 706+/-243 (455-1129) nGy h(-1). The concentration of radon was measured in phosphorite mines and in the warehouses for SSP fertilizer by an active method. Protective measures have been proposed to control the pollution in the phosphorite mining and processing, and fertilizer storage areas.