Calculation of the annual effective radiation dose arising from four radionuclides present in tobacco

Keith Thompson JT International SA, 1 rue de la Gabelle, CH-1211 Geneva 26, Switzerland.

INTRODUCTION RESULTS 2012_SSPTPOST23_Thompson.pdf The presence of radionuclides in tobacco was first reported in the scientific literature in the early The annual effective radiation doses arising from exposure to caesium-137, lead-210, polonium-210 and 1950s (1). It has since been suggested that the presence of radionuclides, and in particular lead-210 potassium-40 are shown below in Table 1 along with the range of values found in the literature: and polonium-210, is at least partly responsible for the increased incidence of lung cancer observed in smokers (2,3). Several authors have attempted to quantify the dose of radiation originating from Literature Radionuclide R C t T(%) F (Sv/Bq) E (µSv/y) use of tobacco products. However, significant heterogeneity exists with regard to their findings (see Range Table 1). 2.07x10-4 Caesium-137 0.4Bq/kg 20 365 1 8.70x10-9 7.4-410.4nSv/y This work aims to accurately estimate the radiation dose arising from four radionuclides present in (0.207nSv/y) tobacco using the most suitable values identified in the literature. Lead-210 15mBq/cig 20 365 8 1.10x10-6 9.64 5.7-480μSv/y

METHOD Polonium-210 15mBq/cig 20 365 13 3.30x10-6 46.98 19-600μSv/y A review of the scientific literature was undertaken to identify all relevant articles on the topic of radioactivity in tobacco. Experimental transfer rates for radionuclides from tobacco to mainstream Potassium-40 1500Bq/kg 20 365 0.75 4.66x10-9 0.31 15.8-50.1μSv/y smoke were identified. These were used in conjunction with dose conversion factors and experimentally determined levels of radionuclides in un-burnt tobacco to determine annual effective radiation doses for four radionuclides in tobacco: caesium-137, lead-210, polonium-210 and Table 1: Summary of the annual effective radiation doses arising from four radionuclides present in tobacco potassium-40. CONCLUSIONS The annual effective radiation dose was determined using the following formula: • The annual effective radiation dose originating from polonium-210, lead-210 and potassium-40 in tobacco products can be estimated at 47µSv/year, 10µSv/year and 0.3µSv/year respectively based on the most recent E = R x C x t x T x F data. • The annual effective dose which arises from caesium-137 exposure is significantly less than 1nSv. The Where E is the annual effective radiation dose (Sv/year or magnitudes thereof), R is the presence of artificially generated radionuclides such as caesium-137 in tobacco does not significantly increase concentration of the radionuclide in the un-burnt tobacco, C is the cigarette consumption per day, t is the existing radiological burden which arises from the use of tobacco products. the duration of smoking, T is the transfer rate from the tobacco to the mainstream smoke and F is the • The combined annual effective dose which arises from the three naturally-occurring radionuclides present in dose conversion factor for the radionuclide in question (Sv/Bq). tobacco for which sufficient data is available (lead-210, polonium-210 and potassium-40) can be estimated at 57µSv per year. This represents less than 5% of the mean annual effective radiation dose obtained through Cigarette consumption was fixed at 20 cigarettes per day over the course of one year. Dose background inhalation of radon-222 gas (estimated by UNSCEAR at 1.26mSv) (4). conversion factors for inhalation of radionuclides in adults were taken from UNSCEAR (4) apart from • The annual effective radiation doses available in the scientific literature significantly over-estimate the true that for potassium-40 which was taken from Shousha and Ahmad (5). For lead-210 and polonium- extent of radiation exposure which occurs through use of tobacco products. This occurs mainly due to the use 210, the weight of tobacco per cigarette was fixed at 0.8g (6). of inappropriate transfer rates for radionuclides from tobacco to mainstream smoke.

REFERENCES (1) Spiers, F.W., and Massey, R.D. Radioactivity of tobacco and lung cancer Lancet (1953) 265 (6798), 1259-1260. (2) Radford, E.P., and Hunt, V.R. Polonium-210: a volatile radioelement in cigarettes Science (1964) 143 (3603), 247-249. (3) Karagueuzian, H.S., White, C., Sayre, J., and Norman, A. Cigarette smoke radioactivity and lung cancer risk Nicotine and Tobacco Research (2012) 14 (1), 79-90. (4) United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Sources of Ionizing Radiation. Volume I: Report to the General Assembly, Scientific Annexes A and B (2008). (5) Shousha, H.A., and Ahmad, F. Natural radioactivity contents in tobacco and radiation dose induced from smoking Radiation Protection Dosimetry (2012) 150 (1), 91-95. (6) Schayer,© Copyright S., Nowak, JTI B., 2011 Wang, Y., Qu, Q., and Cohen, B. 210Po and 210Pb activity in Chinese cigarettes Health Physics (2009) 96 (5), 543-549.

Congress2012 - Document not peer-reviewed by CORESTA