Abstract
Administration of 0.1% isonicotinic acid hydrazide in drinking water to 9 week old ASW/Sn mice and to 5 week old MRC rats for the remainder of their lifetime resulted in an enhanced incidence of pulmonary tumors in the former species. It rose from 34 to 68% in the females as compared with the controls, while in the males, the treatment did not affect the development of these lesions nor did it increase the incidences of other types of tumors. In rats, the compound was also without any apparent carcinogenic effect. The possible role of this chemical in tumorigenesis is discussed in light of the obtained results.