DISTRIBUTION OF PO-210 IN THE HUMAN-LUNG

Polonium-210 has been measured in the tracheobronchial tree and parenchyma of cigarette smokers and nonsmokers in order to determine whether this α emitter is retained in smokers. The ratio of 210Po concentration in the tracheobronchial tree (T) to that in the lung parenchyma (P) in nonsmokers is T/P = 2.7 ± 0.5. The ratio in smokers is T/P = 1.1 ± 0.2. The difference in these ratios can be related to retention of 210Po, or its 210Pb precursor in the parenchymal tissue. About 5 pCi desposited and retained on alveolar surfaces and an average excess of 0.3 pCi 210Po retained on the tracheobronchial tree is estimated for smokers. Measurements in exsmokers result in a ratio (T/P) = 0.8 ± 0.4 and is possibly related to long-term retention of deposited 210Pb in alveolar tissue.