A BRIEF OVERVIEW OF THE CAUSES OF LUNG CANCER AND MEASUREMENTS OF RADON CONCENTRATIONS

Abstract

Ionizing radiation is a well-established carcinogen. A great number of epidemiologic and experimental studies demonstrated that radiation can cause most forms of cancer. Largest contribution to the exposure of general population by ionizing radiation comes from natural sources. Sources of ionizing radiation in a human's normal living environment are cosmic rays, terrestrial and internal radiation. In average, natural background radiation is responsible for annual effective dose of about 2-3 mSv although this value varies in wide range around the world and one can easily find the areas with up to 10 times greater exposures, mainly due to high levels of radioactive gas – radon. In general, inhalation of radon gas and its progeny is responsible for the greatest component of annual exposure of an average person (about 50%). In the article the causes of lung cancer are discussed. The most important cause of lung cancer is tobacco smoke. According to some estimates, about 90% of lung cancer cases are resulted from smoking.  However, it is generally recognized that there are other risk factors, as well. The radon represents the second most important cause of lung cancer after tobacco. Indoor radon concentrations can vary greatly between different geographic regions and different types of building structures. In addition, they exhibit a large range of temporal variations. Since radon emanates from the soil beneath the building, the highest concentrations will be found in basements and first-floor rooms. However, more extensive and large-scale measurements and studies are needed. Assessment of radon concentration levels in different types of buildings throughout the country will allow to estimate the radiation doses due to radon exposure and associated risks for different population groups in Georgia.          
       The results of the research obtained at some test objects in three districts of Tbilisi - Vake, Saburtalo, Nadzaladevi settlements, are also presented. Radon concentrations in apartments and soil gas has been measured, and gamma radiation background was determined also.