A short-term organ culture of rat tracheal epithelium was used to detect the ability of 53 chemicals to induce UDS. In this system all direct-acting compounds (ultimate or proximate
carcinogens) tested induced UDS. Of 24 compounds requiring metabolism (procarcinogens), nine induced UDS, viz., 4NQO,
AF-2, BP, DMN, DEN, and NP.
Urethane, AAF, and 2,7-AAF induced very slight UDS. 3-Methyl-4NQO for which carcinogenicity data is incomplete as positive in our system. Among the
cancer chemotherapeutic agents tested only
mitomycin C induced UDS. MC and DMBA, which are known to induce
cancer of respiratory organs in experimented animals, and DAB,
aflatoxin B1 and
Trp-P-1, which are strong
carcinogens in the liver, did not induce UDS within 2 h. With the longer exposure (24 h), these
carcinogens also failed to elicit UDS. All the
carcinogens that induce UDS showed clear dose-dependent effects. No non-
carcinogens tested induced UDS. These results suggested that this system should be useful for screening environmental chemicals suspected of damaging
DNA of the respiratory organ on the basis of organotropic effects for UDS induction in cultured rat tracheal epithelium.