Mapping of outdoor gamma radiation and consequential health risk assessment in north-eastern regions of Rajasthan, India

Living beings get inevitable exposure to radiation of which approximately half of the dose is due to natural background radiation. In the present study, an extensive and systematic survey of outdoor GDR (GDR) was carried out in Churu and Jhunjhunu districts of Rajasthan. A total of 687 locations were covered to quantify the outdoor GDR. The portable radiation monitor, based on the Geiger-Muller counter, was used to monitor the outdoor gamma dose, and its associated health risk was estimated. Outdoor GDRs were found to vary from 32 nSv/h to 231 nSv/h and 75 nSv/h to 188 nSv/h in Churu and Jhunjhunu districts, respectively. The annual effective dose at most locations of the study area was greater than 0.07 nSv/h but less than the 1 mSv/y permissible limit recommended by the ICRP. The excess lifetime cancer risk in Churu district was estimated and found to range from 0.147 x 10(-3) to 1.063 x 10(-3), while in Jhunjhunu district it was 0.345 x 10(-3) to 0.865 x 10(-3)