CHARACTERIZATION OF DEVELOPMENTAL TOXICITY OF MONO-N-BENZYL PHTHALATEIN RATS

The objective of this study was to characterize the developmental toxi city of mono-n-benzyl phthalate (MBeP), which is one of the major meta bolites of n-butyl benzyl phthalate, Pregnant rats were given MBeP by gastric intubation at 250, 375, 500, or 625 mg/kg on days 7 to 9, 10 t o 12, or 13 to 15 of pregnancy, A significantly increased incidence of postimplantation loss was found at 500 mg/kg and above regardless of the days of administration, While administration of MBeP on days 7 to 9 or 13 to 15 at 375 mg/kg and above was significantly teratogenic, no evidence of teratogenicity was detected when MBeP was given on days 1 0 to 12, Deformity of the vertebral column and ribs and dilatation of the renal pelvis were frequently observed after administration on days 7 to 9, Cleft palate and fused sternebrae were exclusively found afte r administration on days 13 to 15, These findings indicate that the su sceptibility and spectrum of the developmental toxicity of MBeP vary w ith the developmental stages at the time of administration.