Evaluation of the teratogenic potential of the plasticizer butyl benzyl phthalate in rats.

The teratogenicity of butyl benzyl phthalate (BBP) was studied in Wistar rats. Pregnant rats were given BBP at a dosage of 0, 0.25, 0.5, 1.0 or 2.0% in the diet from day 0 to day 20 of pregnancy. Daily intakes of BBP were 185 mg kg-1 for the 0.25% group, 375 mg kg-1 for the 0.5% group, 654 mg kg-1 for the 1.0% group and 974 mg kg-1 for the 2.0% group. Adjusted maternal body weight gain (body weight gain excluding the gravid uterus) during pregnancy in the 1.0 and 2.0% groups was significantly lowered. Food consumption during pregnancy in the 0.25 and 0.5% groups did not differ from that in the control group. No death was noted in the pregnant females of any group. There was no significant compound-related effects on the incidence of preimplantation loss. All dams given 2.0% BBP exhibited complete resorption of all the implanted embryos. Morphological examinations of the fetuses revealed no evidence of teratogenesis. It could be concluded that the no-observable-effect-levels (NOEL) in rats were 0.5 and 1.0% BBP in the diet for maternal and embryofetal toxicity, respectively.