Cancer risk assessment after exposure from natural radionuclides in soil using Monte Carlo techniques

Abstract

Purpose: The purpose of this paper is to assess fatal cancer risk after external and internal (inhalation and ingestion) exposure from natural radionuclides in soil like 238U, 232Th, 40K, and 226Ra on the territory of Bela Crkva, Serbia. Although receiving doses are low from sources like natural radionuclides in soil, because of stochastic effects of ionizing radiation, risk for developing cancer exists and can be quantified. Methods: Concentrations of radionuclides from 80 soil samples are measured using HPGe detector. Fatal cancer risk is assessed from calculated ambient dose rate in the target organs of body due to external and internal exposure. Monte Carlo simulations are used to obtain conversion factors which are required to calculate absorbed dose rate in target organs. Results and discussion: Assessed cancer risk for 238U in the case of both inhalation and ingestion exposure is from 1.11×10-6 to 24×10-6 for minimal and maximal activity in soil samples, from 1.02×10-6 to 23.3×10-6 for exposure to 226Ra, from 1.89×10-6 to 50.3×10-6 for exposure to 232Th, and from 0.265×10-6 to 9.83×10-6 for exposure to 40K. Overall risk from 40K as external and internal source is from 0.8×10-6 to 31.9×10-6. Calculated cancer risks from both inhalation and ingestion exposure could be related to all tissues that are on the way of distribution of particles within the body but especially to deposition sites in the body. Conclusion: Assessed risks for fatal cancer development from inhaled and ingested natural radionuclides originating in soil are not increased. © 2010 Springer-Verlag.