Polonium in size fractionated mainstream cigarette smoke, predicted deposition and associated internal radiation dose.

In this study, size fractionated mass and Po activity concentrations in mainstream cigarette smoke (MCS) were monitored for three popular cigarette brands. Size segregated collection of MCS was carried out using a cascade type impactor, while mass and Po activity concentration were analyzed gravimetrically and alpha spectrometry (following the radiochemical separation) respectively. Multiple-Path Particle Dosimetry (MPPD V2.11) model is used for prediction of deposition fraction calculations for the MCS deposition in different compartment of human respiratory tract. The activity concentration of Po is founds 10.56 ± 2.46 mBq per cigarette for the tested cigarette brands. Po size distribution indicates most of this associates with fine fraction (Dp < 2.23 μm) of cigarette smoke. The committed annual effective dose to smokers (smoking on an average 20 cigarette a day), considering the Po and Pb concentrations (assuming it is in secular equilibrium with Po) in MCS, was estimated between 0.22 and 0.40 mSv, with mean value of 0.30 mSv for tested cigarette brands. Considering the risk factor of fatal cancer due to radiation exposure of lung (exposure time of 30 years); the average collective estimated fatal cancer risk is estimated as 1.5 × 10 due to Po and Pb exposure to smokers.