The effect of prenatal exposure to a repeat high dose of toluene in the fetal rat

Solvent abuse during pregnancy results in a clinical pattern of adverse outcomes including deafness. The aim of this project was to determine whether high doses of toluene for a short duration during pregnancy produced adverse outcomes in the fetal rat. Pregnant rats were given either 1250 mg/kg of toluene or peanut oil by gavage from gestation day 16–19. The study demonstrated that administration of toluene at the dose used did not result in significant maternal toxicity. However, some maternal renal pathology was noted. There was no significant difference in placental or fetal weights nor was there a significant difference in the number of external or skeletal malformations of fetuses between treatment and control groups. Treated fetuses had an increased frequency and severity of enlarged renal pelveses. A pattern of accelerated development in the upper mid-turn and sometimes apical turns in the treated fetal cochleas was observed. This accelerated development suggests that toluene may induce excessive cell death resulting in premature maturation of the cochlea.