Tumorigenesis by Benzo(a)pyrene Administered Intracolonically

Benzo(a)pyrene (BP) was administered to Swiss mice in 1 and 10 weekly intracolonic instillations at 200 μ g/g body weight. The single administration of BP induced a statistically significant incidence of malignant lymphomas and tumors of the forestomach, while its repeated instillation, evoked, in addition to these two tumor types, neoplasms in the esophagus, anus and skin. BP failed to elicit intestinal tumors, which was the main objective of the present investigation. We discuss, in light of the obtained results, the various experimental conditions under which studies were conducted of this most versatile and widely occurring carcinogen, to which a large segment of the human population is exposed.