National Toxicology Program

Developmental Toxicity of Butyl benzyl phthalate (CAS No. 85-68-7) in CD-1 Swiss Mice

NTP Study: TER89026

ABSTRACT

Butyl benzyl phthalate (BBP) a phthalate ester plasticizer, was evaluated for maternal and developmental toxicity in timed- pregnant Swiss albino (CD-l) mice (n=28-30 per group, except n=14 at 2.0% BBP). BBP (0, 0.1, 0.5, 1.25 or 2.0% in feed) was administered between the mornings of gestational day (gd) 6 and 15. At sacrifice (gd 17), the status of implantation sites was recorded; each fetus was weighed and examined for external, visceral and skeletal malformations. No maternal or embryo/fetal effects were observed at 0.1% BBP (0.182 g/kg/day). At 0.5% BBP (0.910 g/kg/day), maternal effects were limited to a 15% reduction in wt. gain during treatment. The percent nonlive implants/litter (i.e., resorptions plus late fetal deaths) was increased at 0.5% BBP (15% vs. 8% for controls), as was the percent fetuses malformed/litter (14% vs. 4%). Dams in the 1.25% BBP (2.330 g/kg/day) group showed a 71% reduction in gestational wt. gain, a 66% reduction in treatment wt. gain, and a 25% reduction in corrected wt. gain. Absolute liver wt. was decreased, and relative liver and kidney wts. were increased in the absence of treatment-related microscopic lesions. Relative food intake (g/kg/day) was increased by 27% (gd 15 to 17) and relative water intake by 35-36% (gd 12 to 17). Also at 1.25% BBP, the percent nonlive implants/litter was increased (93% vs. 8%), average fetal body wt./litter was reduced by 17%, and the percent malformed fetuses/litter was increased (89% vs. 4%). The 2.0% BBP dose (4.121 g/kg/day) was eliminated after evaluation of 14 dams since all implanted conceptuses were resorbed. In summary, 0.1% dietary BBP was a no-observed-adverse-effect level (NOAEL) for both maternal and developmental toxicity. At 0.5%, BBP produced minimal evidence of maternal toxicity (reduced wt. gain during treatment) and significant developmental toxicity (increased prenatal mortality and malformations). At 1.25% BBP and 2.0%, significant maternal and embryo/fetal effects were observed, including greater than 90% prenatal mortality.

Report Date: June 22,1990

NTIS# PB91-129999

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