Abstract

PIP: Concentrations of the alpha-particle-emitting radioactive element polonium was measured in various pulmonary tissues of smokers and nonsmokers in order to determine 1) whether this radiation exposure is associated with the development of bronchial cancer in smokers; and 2) how smoke is absorbed and excreted in human lungs. Lung specimens from 25 current cigarette smokers, 2 current pipe smokers, 1 former cigarette smoker, and 8 nonsmokers ere analyzed. The average concentration of polonium in the peripheral parenchyma of current smokers was .0074 picocurie/gm and in nonsmokers was .0016. For smokers, the average concentration was doubled in more centrally located parenchyma and was greater in the upper than in the lower lobes. Polonium concentrations correlated with daily cigarette consumption but not with total cigarettes smoked. The concentrations in peribronchial lymph nodes of smokers were also higher than in nonsmokers. These values show no correlation with total or daily cigarette consumption. Polonium concentration was similiar in bronchial wall parenchyma as in lung parenchyma but was greater in bronchial epithelium than in parenchymal or lymph nodes. The patterns of distribution of polonium throughout the lung suggest that most inhaled smoke particles are rapidly cleared from the lung, and polonium is primarily cleared by mucus sheet. Since the highest local concentrations of polonium were found in bronchial epithelium from segmental bifurcations, leading to a high cumulative local radiation dose, polonium may be implicated in the initiation of bronchial cancer in humans.