EXECUTIVE SUMMARY

N-Carboxymethyl-N-nitrosourea (CMNU) is a naturally occurring compound that is formed primarily from the reaction of glycocyamine and nitrite, which are present in the diets of most individuals. The typical daily dose of CMNU received by humans is unknown, but is expected to vary widely and depend primarily on nitrite and meat intake.
CMNU administered in the drinking water induced adenocarcinomas of the large and small intestine in two independent studies, one in male MRC Wistar rats and another in female Donryu rats. Treatment-related increases in squamous cell carcinoma of the skin were observed in male rats, and increases in squamous cell oral cavity and Zymbal's gland tumors were significant by trend test in female rats. CMNU has not been tested for carcinogenicity in mice.

CMNU is a direct acting mutagen and clastogen. CMNU induced mutations in several strains of bacteria and caused a wide array of chromosomal aberrations in mammalian cells in vitro. CMNU bears strong structural resemblance to other N-alkyl-N-nitrosourea compounds (e.g., N-ethyl-N-nitrosourea), which are carcinogenic in rodents, pigs and primates.

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