A member of the class of N-nitrosoureas that is urea in which one of the nitrogens is substituted by methyl and nitroso groups. California Office of Environmental Health Hazard Assessment (OEHHA): N-Nitroso-N-methylurea can cause cancer according to an independent committee of scientific and health experts.ChEBI: N-methyl-N-nitrosourea is a member of the class of N-nitrosoureas that is urea in which one of the nitrogens is substituted by methyl and nitroso groups. It has a role as a carcinogenic agent, a mutagen, a teratogenic agent and an alkylating agent.