A study in hamsters of the distribution and elimination of radioactivity after a single intratracheal instillation of a suspension of [3H]3,4-benzopyrene (BP) in aminosol vitrum 100%, or of mixtures of BP and asbestos or of BP and carbon black in the same suspending medium, is reported. During the first 3 weeks of the experiment, radioactivity disappeared rapidly from the lungs irrespective of the presence or absence of carbon black. After 21 days, however, both asbestos and carbon black significantly increased retention of radioactivity. More macrophages could be recovered by use of a standard washing technique after the administration of BP + carbon black or BP + asbestos, than after the administration of BP alone, but the radioactivity per macrophage was highest in the group treated with benzopyrene only. The levels of radioactivity found in liver, kidneys, blood and urine were similar in the 3 groups of animals. In the faeces there was an earlier fall of radioactivity after treatment with BP + carbon black (between 14 and 21 days) than after treatment with BP alone (between 21 and 28 days. The significance of the results in relation to the causation of lung cancer in man is briefly discussed. © 1969, The British Empire Cancer Campaign for Research. All rights reserved.
