Environmental risk of natural radiation sources

People are continually exposed to ionizing radiation from natural sources like radionuclide ⁴⁰K. Simulation of radiation transport processes, from source in environment to organism, enables dose estimations which can be related to certain stochastic or deterministic effects. Purpose of this study was to estimate absorbed dose rate in air using Monte Carlo method, and to estimate ambient dose equivalent. Estimating values of these two quantities enable further risk assessment. 30 soil samples were collected from 10 uncultivated locations in Serbia. Activity concentrations were measured using HPGe detector. Mean value of absorbed dose rate in air 1 m above ground is 19 nGy/h, (range (4 - 29) nGy/h). Mean value of ambient dose equivalent for infinite soil depth is 26 nSv/h, (range (6 - 41) nSv/h) and mean value for soil depth of 15 cm is 22 nSv/h, (range (5 - 33) nSv/h). Although receiving doses are low from exposure to ⁴⁰K radionuclides occurring in soil, according to linear-no-threshold approach, risk exists, but it is very small.