Estimation of radioactivity in tobacco

The link between cigarette smoke and cancer has long been established. Smokers are ten times at greater risk of developing lung cancer than that of non-smokers. Tobacco fields and plants also have higher concentration of uranium and consequently large contents of 210Po and 210Pb belonging to uranium and radium decay series. These radio-nuclides have long association with tobacco plants. 210Pb and 210Po, decay products of the uranium series get dissolved in water and are first transported into plants and subsequently to the human being. Also, the uptake of radionuclides into roots from the soils and phosphate fertilizers along with direct deposition of 210Pb by rainfall represents the principal mechanism of incorporation of 210Pb and 210Po into the tobacco plants. Uranium present in soil enters the plants through roots and gets distributed in various parts of the tobacco plants. This phenomenon may cause high intake of uranium and its radioactive decay products leading to harmful effects in human being. In the present work, Gamma spectrometry (HPGe detector of high-resolution gamma spectrometry system) has been used at Inter University Accelerator Center (IUAC), New Delhi, for the measurement of activity concentrations of 238U, 232Th and 40K in some tobacco samples. The alpha radioactivity of the leaves of the tobacco plants was measured using plastic track detectors LR-115 Type-Il manufactured by Kodak. Measurement of track densities (track cm-2 day-1) shows variation on the upper face and the bottom face of the leaves for the plants. The track density due to alpha particles is higher at bottom face as compared to top face of the leaves. (author)