Further evaluation of developmental toxicity of di-n-butyl phthalate following administration during late pregnancy in rats.

The objective of this study was to further evaluate the developmental toxicity of di-n-butyl phthalate (DBP) administered during the second half of pregnancy. Pregnant rats were fed a diet containing DBP at a dose of 0 (control), 0.5, 1.0 or 2.0% ad libitum on days 11-21 of pregnancy. Average daily intakes of DBP were 331, 555 and 661 mg/kg for the 0.5, 1.0 and 2.0% groups, respectively. No significant changes induced by DBP were detected in the incidence of postimplantation loss and numbers of live fetuses and of resorptions and dead fetuses. The weights of male and female fetuses at 2.0% DBP were significantly decreased. The incidences of fetuses with cleft palate and fetuses with fusion of the sternebrae at 2.0% DBP and fetuses with undescended testes at 1.0 and 2.0% DBP were significantly increased. There were significant decreases in the anogenital distance (AGD) of male fetuses in the 1.0 and 2.0% DBP groups, also. AGD of female fetuses in the DBP-treated groups was comparable to that in the control group. It was concluded that DBP administered during the second half of pregnancy produced adverse effects on the reproductive development in male fetuses.