ABSTRACT
Until recently, the nasal epithelium of laboratory rodents has not been widely recognized as an important target site for carcinogenesis bioassays of environmental substances. This was probably due to a variety of factors, including the extremely low incidence of spontaneous nasal cavity neoplasms in rodents; the difficulty of examination and preparation of this intricate organ for histopathological assessment; the lack of familiarity of many pathologists with the normal histology and pathological lesions of this site; and the erroneous opinion that the nasal epithelium is of low sensitivity to carcinogens, especially those applied sys-temically. The induction of nasal carcinomas by systemic exposure to several different environmental agents and nitrosamines during the last decade has demonstrated the sensitivity of this site and has forced a reevaluation of the importance of the nasal cavity as an endpoint in carcinogenesis bioassays.
