Developmental toxicity of mono-n-benzyl phthalate, one of the major metabolites of the plasticizer n-butyl benzyl phthalate, in rats.

Mono-n-benzyl phthalate (MBeP), one of the major metabolites of the plasticizer n-butyl benzyl phthalate, was evaluated for developmental toxicity in Wistar rats. Rats were given MBeP by gastric intubation at 0, 250, 313, 375, 438 or 500 mg/kg from day 7 through day 15 of pregnancy. Significant decreases in the maternal body weight gains and food consumption during administration period were observed at 313 mg/kg and above and at 250 mg/kg and above, respectively. Significant increase in the incidence of postimplantation loss per litter was found at 438 and 500 mg/kg. The incidences of fetuses with external malformations at 438 mg/kg, of fetuses with skeletal malformations at 313 mg/kg and above and of fetuses with internal malformations at 375 mg/kg and above were higher than those in the control group. Defects in the cervical and thoracic vertebrae, ribs and kidney were frequently observed.