Activity of urethane and N,N-dimethylurethane in the mouse bone-marrow micronucleus assay: equivalence of oral and intraperitoneal routes of exposure.

Urethane is shown to be active in the mouse bone-marrow micronucleus assay when administered as a single dose by either gavage or intraperitoneal injection. The magnitude of the response using the two routes was not statistically significantly different. N,N-Dimethylurethane (DMU) is shown to be mutagenic to Salmonella and active in the bone-marrow micronucleus assay by both routes of administration. The activity of DMU in the bone marrow precludes elimination of ethanol, yielding cyanate ion, as an explanation for the micronucleus-inducing activity of urethane.