On the embryotoxic effects of benzene and its alkyl derivatives in mice, rats and rabbits.

Groups of CFY rats were exposed to inhalation of ethylbenzene at 600, 1200 or 2400 mg/m3 or xylene at 250, 1900 or 3400 mg/m3 or Aromatol at 500, 1000 or 2000 mg/m3 atmospheric concentration for 24 h/day from day 7 to day 15 of pregnancy, or for 2-4 hours only on the 18th or 20th day of gestation. CFLP mice and NZ rabbits were exposed to inhalation of 500 mg/m3 or 1000 mg/m3 benzene, toluene, ortho-, meta-, para-xylene, ethylbenzene, xylene or Aromatol for 24 h/day from day 6 to day 15 of pregnancy. Untreated animals and groups inhaling pure air served as controls. All components of the xylene and Aromatol crossed the placenta and were present in fetal blood and amniotic fluid, as well. The maternal toxic effects at all solvents were moderate and dose dependent. All solvents (at higher concentrations) brought about skeletal and weight retardation in fetuses of rats and mice. At highest concentration some solvents increased the post-implantation loss in rats and mice. All solvents caused spontaneous abortion in rabbits at 1000 mg/m3 atmospheric concentration. Only ethylbenzene and Aromatol increased the malformation rate in rats and mice. No other solvent applied proved to be teratogenic either in mice, rats or rabbits.