Carcinogenic effect of N-ethyl- and N-amyl-N-nitrosourethans on female Donryu rats.

Carcinogenic effect of N-ethyl-N-nitrosourethan (ENUR) and N-amyl-N-nitrosourethan (ANUR) was examined by continuous oral administration or topical application to female Donruy rats. Oral administration of 100 ppm solution of ENUR induced 100% of tumors in the forestomach, 46%, 80%, 71%, and 51% in the oral cavity and pharynx, esophagus, duodenum, and liver, respectively. On the other hand, the incidence of forestomach tumors was 78%, that of oral cavity and pharynx, and esophagus was 93% and 98%, respectively, in rats given 400 ppm suspension of ANUR. In addition, topical application of ENUR induced tumors of the skin as well as tumors of the forestomach and liver.