Induction of dominant-lethal mutations after administration of ethylenethiourea in combination with nitrite or of N-nitroso-ethylenethiourea in mice

Mutagenic potentials of ethylenethiourea (ETU) in combination with sodium nitrite or of N-nitroso-ETU, a nitrosttion product of ETU in vitro, were investigated in the mouse dominant-lethal test. Simultaneous 5-day p.o. administration of ETU (150 mg/kg) and sodium nitrite (50 mg/kg) caused a significant decrease in the percentage pregnancy and the number of implants in weeks 5 and 6 of testing, although no effects were obtained on these indices when the chemicals were applied separately. However, in the group treated with 30 mg ETU plus 10 mg sodium nitrite per kg no dominant-lethal mutations were induced. 5-day oral administration of 100 mg of N-nitroso-ETU per kg also exhibited similar effects to those observed after treatment with 150 mg ETU plus 50 mg sodium nitrite per kg.