Low dose exposure to radionuclides in soil

Abstract

Radionuclide sources, natural and man-made, contribute to continual exposure to ionizing radiation. Exposure to natural radionuclide sources in the Earth's crust, such as 238U and 232Th series, is present everywhere, but industry development contributes to the growing level of exposure to man-made sources released into the environment. Constant monitoring of activity concentrations and received doses is a very important part in radiation protection of the population and professionally exposed persons. The impact of the environment on human life is in research focus. Effects from low dose exposure that arise from natural sources in soil remain controversial. Epidemiological studies, as the only tool that can provide us direct measurement of a risk, cannot detect a small increase in a risk after exposures to low doses because of high background cancer rates. General authorities still use the linear no threshold model as the most reliable where risk after exposure to low dose is extrapolated from higher doses. Still, uncertainties are very high and future research should be based on carefully designing epidemiological studies of exposed and control populations. A great effort was made in Serbia in the past 20 years in research of soil radioactivity and production of geopathological maps. These types of investigations are very important because of agriculture production and in the production of organic food, which has great potential. A recent study focused on measuring activity concentrations of 137Cs and 40K in soil samples in the province of Vojvodina and in the territory of Belgrade. Using dose conversion factors taken from "EPA Federal Guidance Report 12," annual effective doses from external sources were estimated. The lifetime cancer mortality risk was assessed using cancer risk coefficients taken from the "EPA Federal Guidance Report 13." Monte Carlo simulations were used for obtaining dose equivalents in a detector composed of tissue equivalent material positioned 1 m above the ground. © 2012 Nova Science Publishers, Inc. All rights reserved.