[Correlation between the fetotoxic effect of benzol inhalation in CFY rats and benzol concentration in the inhaled gas].

CFY rats from the 7th to the 14th days of pregnancy were given benzole to inhale during 24 hours a day in doses 150, 450, 1500 or 3000 mg/m3 (50, 150, 500 or 1000 ppm). It was established that benzole has no teratogenous effect in rats. Frequency of the obvious malformations of the scelet and soft tissues has not increase at any doses given. The concentration of benzole 150 mg/m3 has induced moderate, 450 mg/m3 marked maternal and foetal toxicity i.e. increase of the maternal mortality rate, damage to the circulation, decrease in the gain of the body weight and that of the placenta, increase of the foetal mortality rate (early and late) and retardation of the foetal development. Further increase of the concentration of the benzole was not followed by more severe toxical symptoms. Authors conclude, that women already before the onset of the planned pregnancy should avoid benzole exposition.