Radioactivity of cigarettes and the importance of Po-210 and thorium isotopes for radiation dose assessment due to smoking

摘要

Tobacco and tobacco smoke are very complex mixtures. In addition to various chemical and organic compounds they also contain natural radioactive elements (radionuclides). In this work, the natural radionuclide activity concentrations (U-234, U-238, Th-228, Th-230, Th-232, Ra-226, Pb-210 and Po-210) of nine different cigarette samples available on the Slovenian market are reported. In addition to Po-210, the transfer of thorium isotopes from a cigarette to a smoker's body and lungs have been determined for the first time. Cigarette smoke and exhaled air from smokers' lungs were collected from volunteer smokers (C-4 brand) to determinate what quantity of Po-210 and thorium isotopes is transferred from the tobacco to the smoker's lungs. Cigarette ash and smoked filters were also collected and analysed. Among the determined isotopes, Pb-210 and Po-210 showed the highest activity concentrations. During the smoking of one cigarette approximately 22% of Po-210 (and presumably its predecessor Pb-210), 0.6% of Th-228, 24% of Th-230, and 31% of Th-232 are transferred from the cigarette and retained in the smoker's body. The estimated annual effective dose for smokers is 61 mu Sv/year from Po-210; 9 mu Sv/year from Pb-210; 6 mu Sv/year from Th-228; 47 mu Sv/year from Th-230, and 37 mu Sv/year from Th-232. These results show the importance of thorium isotopes in contributing to the annual effective dose for smoking. (C) 2016 Elsevier Ltd. All rights reserved.