Radioactivity of cigarettes and the importance of 210Po and thorium isotopes for radiation dose assessment due to smoking. (May 2016) - Kubalek, Davor
Abstract: 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 ( 234 U, 238 U, 228 Th, 230 Th, 232 Th, 226 Ra, 210 Pb and 210 Po) of nine different cigarette samples available on the Slovenian market are reported. In addition to 210 Po, 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 210 Po 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, 210 Pb and 210 Po showed the highest activity concentrations. During the smoking of one cigarette approximately 22% of 210 Po (and presumably its predecessor 210 Pb), 0.6% of 228 Th, 24% of 230 Th, and 31% of 232 Th are transferred from the cigarette and retained in the smoker's body. The estimated annual effective dose for smokers is 61 μSv/year from 210 Po; 9 μSv/year from 210 Pb; 6 μSv/year from 228 Th; 47 μSv/year from 230 Th, and 37 μSv/year from 232 Th. These results show the importance of thorium isotopes in contributing to the annual effective dose for smoking. Graphical abstract: Highlights: Transfer of 210 Po, 210 Pb and thorium isotopes from cigarette to a smoker's body and lungs were determined. Thorium isotopes retained in smoker's lungs along with 210 Po and 210 Pb. contribution of thorium isotopes to the radiation dose due to cigarette smoking is higher than for 210 Pb and 210 Po.