Tumor induction by a single subcutaneous injection of N-methyl-N'-nitro-N-nitrosoguanidine and its derivatives in newborn mice.

N-Methyl-N'-nitro-N-nitrosoguanidine (MNNG), or its derivatives N-hexyl-N'-nitro-N-nitrosoguanidine (HNNG) and 1,6-bis(N'-nitro-N-nitrosoguanidinyl)-n-hexane (HxBNNG) were given to newborn ICR/JCL mice by a single subcutaneous injection in 1% gelatin suspension. In an acute toxicity study, the maximum tolerated dose of MNNG, HNNG or HxBNNG was 62 microgram/g, 555 microgram/g, or 500 microgram/g of body weight, respectively. In a chronic study, a single subcutaneous injection of MNNG to newborn mice at a dose of 62, 31, or 3 microgram/g of body weight induced tumors of the lung and hemangioendotheliomas in both sexes, and tumors of the liver in males. Other pathologic findings, such as deformities of the spine and alopecia of the skin, were frequently observed. The incidences of tumors in each group were clearly dose related. HNNG and HxBNNG were not tumorigenic within the observation period.