ORALS

Radionuclides in soil and building material contribute significant background radiation exposure to population. Every living being is exposed to radiation originating from naturally occurring radionuclide, atmospheric radiation, and also from medical treatments. 87% of the radiation dose received by the population is from natural sources [1]. The terrestrial component of the natural background is dependent on the composition of the soils and rocks in which the natural radionuclides are contained. Ground water is in direct contact with the soil and rocks that dissolves many compounds, minerals including uranium and its daughter products and pose inhalation and ingestion dose when used in household activities. If a building is constructed with a material having higher concentration of natural radionuclide, then its indoor radiation dose rate will also be higher, which is the main reason for human lung and stomach cancer [2]. The activity concentration of 226Ra, 232Th and 40K in soil samples were analyzed using p-type coaxial Hyper Pure Germanium (HPGe) detector, 222Rn exhalation rate was measured using Smart Radon Monitor (SRM). 226Ra concentration varied from 22.0 Bqkg-1 to 61.1 Bqkg-1. 232Th concentration ranges from 15.6 to 47.5 Bqkg-1 and 40K concentration ranges from 18.1 Bqkg-1 to 456.0 Bqkg-1. The 222Rn exhalation rate from the soil sample of the study area varied from 2.52 to 13.91 mBqkg-1h-1. The concentration of 226Ra, 222Rn and 210Po in water samples were also measured and inhalation and ingestion dose is estimated. The 222Rn exhalation rate from the construction material varied from 4.65 to 18.34 mBqkg-1h-1. Activity concentration of 226Ra, 232Th and 40K in soil samples were used to estimate 226Ra equivalent activity, internal hazard index, external hazard index and gamma activity concentration index, which lie well below the recommended limit by UNSCEAR 2000 [3].

References:
[1] United Nations Scientific Committee on the Effects of Atomic Radiation, Sources and effects of ionizing radiation: United Nations Publications, Scientific Annexes 49 (1993).
[2] J.H. Lubin, J.D. BoiceJr, Lung cancer risk from residential radon: meta-analysis of eight epidemiologic studies. Jour. National Cancer Institute 89-1 (1997) 49-57.
[3] United Nations Scientific Committee on the Effects of Atomic Radiation, Sources and effects of ionizing radiation: sources. United Nations Publications, 1 (2000)