Importance of the Deposition of Carcinogens for Cancer Induction in Lung Tissue

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Abstract
The kinetics of the elimination of benzo[a]pyrene (BP) from the pulmonary tissue of 201 rats was studied by introduction of different compositions of the suspension and by repeated intubations. The rats were divided into 4 groups, according to the suspension they were given: I: 5 mg BP + 0.5 mg India black-ink powder + 0.2 ml Infusine; II: BP + Infusine; III: BP + black-ink powder + 0.2 ml saline solution; IV: BP + saline solution. Each group was intubated 1, 2, or 3 times at 1-month intervals. On day 1, 3, 5, 7, 18, and 30 after each intubation, 3 rats were examined. The carcinogenic substance was extracted four times from the saponificated mass by ether, and after chromatography the quantity of BP in the sample was determined on an SF-4 spectrophotometer. The results showed that: 1) In 24 hours, about 50 percent of BP was retained in the lung, regardless of the composition of the intubated suspension. 2) The greatest quantity of BP was retained by its introduction with black-ink powder and Infusine together, and true material BP cumulation in the lung tissue by repeated insufflations took place. 3) The minimum quantity of BP was retained by the saline solution alone, and no accumulation by repeated intubations was noted. 4) Repeated insufflations with black-ink powder or Infusine separately did not lead to any considerable accumulation of the carcinogen in the lung tissue. The character, combination, and, possibly, the quantity of the adsorbing agents were the decisive factors of BP accumulation in pulmonary tissue. The importance of the deposition of the carcinogens for cancer induction in the lung is discussed.