210PO IN SOIL AND TOBACCO LEAVES IN QUANG XUONG, VIETNAM AND ESTIMATION OF ANNUAL EFFECTIVE DOSE TO SMOKERS

Review of natural radioactivity in tobacco cigarette brands

Cigarettes smoking are leading causes of lung cancer in the world. In several countries, the radioactivity of tobaccos cigarette brands has been evaluated to estimate the effective dose from smoking inhalation. In this paper, we have reviewed 40 researched papers of radioactivity in tobacco cigarette brands by searching specified databases from various search engines such as Web of Science, Google Scholar, Scopus, Science Direct and PubMed for the studies published between the year 2000 and November, 2023 in English language. Results show that, the arithmetic mean and range of radioactivity concentration in mBq/g were 20.4 (0.4-128.6), 15.4 (2.0-78.8), 630.8 (1.2-1330.0), 8.1 (0.3-41.0), 15.2 (0.2-82.0) and 5.9 (2.0-16.0) from 210Po, 210Pb, 40K, 232Th and 232U and 226Ra, respectively. The annual effective doses were also estimated using the assumption that a smoker smokes 20 cigarettes per day. The mean annual effective doses in μSv/y from 210Po, 210Pb, 40K, 232Th and 232U and 226Ra were 295, 74.1, 5.80, 889.7, 192.6 and 90.1, respectively. The mean annual effective dose is lower than the reference level 1000 to 20000 μSv/y for existing situation in ICRP Publication 103. The average value of ELCR is 1.03 ×10-3, 0.26 ×10-3,0.02 ×10-3,3.11 ×10-3,0.67 ×10-3 and 0.32 ×10-3 for 210Po, 210Pb, 40K, 232Th and 232U and 226Ra, respectively. The ELCR values obtained in this study are well below the world average value of 1.45 ×10-3. The mean value of LCC in per million is 5.3, 1.3, 0.1, 16, 3.5 and 1.6 for 210Po, 210Pb, 40K, 232Th and 232U and 226Ra, respectively. The values of LCC obtained in this study are all below the limit range of 170-230 per million persons. The result shows 232Th contribute much larger for annual effective dose, annual equivalent dose, ELCR and LCC for smoking tobacco cigarette brands compared to other radionuclides. More studies in radioactivity in tobacco cigarette brands from different countries are required to have conclusive mean annual effective dose, annual equivalent dose, ELCR and LCC for each natural radionuclide.

Dosimetry in the lungs of α-particles (210Po) and β-particles (210Pb) present in the tobacco smoke of conventional cigarettes and heated tobacco products

Tobacco products contain radioactive ²¹⁰Pb and ²¹⁰Po which can be transferred from the filler to the mainstream smoke. When inhaled, they can contribute to the radioactive dose to the lungs and are suspected to significantly contribute to lung cancer from smoking. Currently, no data are available on the radioactive risk of the heated tobacco products (HTP). However, due to the relatively high heat involved in some of these devices, there are concerns about the volatility of polonium particles. Here we used data on the ²¹⁰Po and ²¹⁰Pb content in tobacco smoke along with biokinetic and dosimetric models to compute the effective dose induced by conventional smoking and by using an HTP device (PMI IQOS system). Results show that conventional smoking of one pack per day induces a dose to the lung of about 0.3 mSv/year. This dose decreases by a factor of ten (0.03 mSv/year) for the IQOS system. However, this dose reduction is not obtained by specific countermeasures but by the fact that the IQOS system heats only 15% of the tobacco filler to the target temperature of 330 °C. When heated homogeneously to 300 °C, both conventional and Heets (IQOS) cigarettes release about 80% of the ²¹⁰Po from the tobacco, leading to similar doses to lungs.