The mutagenic effect of carbimazol and methylthiouracil detected by the transplacentar micronucleus test.

The mutagenic effect of carbimazol and methylthiouracil on mice fetal blood in the 15th and 16th day of intrauterine life, as compared to the effect on maternal bone marrow and control animals, was studied using the micronucleus test. The incidence of micronucleated cells was significantly higher in the fetal blood than in the maternal bone marrow. The finding demonstrates that the method of transplacentar mutagenesis is a reliable test for estimating the mutagenic risk of such drugs as carbimazol and methylthiouracil in current therapeutical use.