CYTOGENOTOXICITIES OF SUBLIMED URETHANE GAS TO THE MOUSE EMBRYO

Urethane (ethyl carbamate) which has long been used for commonly used drugs and has proven to be useful in the formation of products in ever y-day use, is volatile, and small amounts sublime spontaneously. Pregn ant ICR mice were maintained in the vinyl chamber (45 liter) which was ventilated 4 times per hour. To inhale urethane gas, air was passed f irst through a glass bottle containing 500 g of crystalline urethane a nd then into the: vinyl chamber. Concentration of the sublimed urethan e gas in the chamber was 1.28 +/- 0.08 mg/l, and sublimed urethane gas produced significantly high incidence of chromosomal aberrations in t he cells of whole embryo, when mice inhaled it for 48 h from day 9 to day 11 of pregnancy. High and significant incidence of chromosomal abe rrations (36.0%) was detected in the embryo 3 h after urethane gas inh alation, but decreased to 5.3% at 24 h after exposure and showed no si gnificant differences from controls after 48 h, while the incidence in bone marrow cells from the adult (pregnant) mice was lower (21.5%) at 3 h after exposure but a significant increase remained until 72 h aft er exposure, A majority of chromosomal aberrations was chromatid types . As a consequence of cellular damages by urethane gas inhalation duri ng pregnancy, significantly high incidence of fetal deaths: and congen ital malformations (cleft palate, polydactyly, tail anomaly etc.) was induced in the offspring. Thus, we must be aware of the risk of volati le chemicals, because it is difficult to perceive and avoid hazardous exposure via respiration.