ABSTRACT
Intratracheal instillation (IT) techniques began to be used for lung carcinogenesis studies in the 1950s. The methods were first described in detail by Della Porta et al. and Te Dunga and Preston. Further development by Saffiotti et al. established IT instillation as common technique for lung carcinogenesis studies. Saffiotti et al. established the technique using Syrian golden hamsters. The main feature of the IT instillation technique is the exclusion of test substances from the upper respiratory tract. Although N-nitroso compounds are well known to induce lung tumors when given parenterally, orally, or by inhalation, the use of N-nitrosamines for lung carcinogenicity studies using IT instillation has been limited. For IT instillation, the ease of exposure, low cost, and ability to administer multiple large doses in a short period of time are major advantages over inhalation. One of the major factors responsible for such species differences would be the different susceptibility of cells at risk in the two species.
