Embryolethality and teratogenicity of butyl benzyl phthalate in rats

Pregnant Wistar rats were given butyl benzyl phthalate (BBP) at a dose of 2.0% in the diet on days 0–20, days 0–11 or days 11–20 of pregnancy. Food consumption and body weight gain were decreased in pregnant rats given BBP. Pre‐implantation loss in the BBP‐treated groups was comparable to that in the control and pair‐fed groups. All dams given BBP on days 0–20 or days 0–11 exhibited complete resorption of all the implanted embryos. No increase in post‐implantation loss was found in pregnant rats given BBP on days 11–20. Marked teratogenicity was detected in fetuses of the dams given BBP on days 11–20. Cleft palate and fusion of the sternebrae were predominantly observed. Seventy‐two of the 134 fetuses had a cleft palate. The incidence of malformations in this group was significantly and markedly higher than that in the control and pair‐fed groups. In conclusion, the administration of BBP during the first and second half of pregnancy produced embryolethality and teratogenicity, respectively.