Abstract

The stellar material, from which the earth was formed, about 4.5 billion years ago, contained many unstable nuclides (Scholten and Timmermans, 1996). Some of the original primordial nuclides, whose half-lives are about as long as the earth's age, are still present. Radiation comes from outer space (cosmic), the ground terrestrial, and even from within over bodies. It present in the air we breathe, the food we eat, the water we drink and in the construction materials used to build our houses. So, radiation is all around us, it is naturally in our environment and it has been since the birth of our planet (Maher and Raed, 2007). Radioactivity of soil environment is one of the major sources of exposure to human (Abusini, 2007). The 235U, 232Th series and natural 40K are the main source of natural radioactivity in soil (Yasir et al., 2007; Vosniakos et al., 2002). Since these natural occurring radio