National Toxicology Program

Developmental Toxicity of Butyl Benzyl Phthalate (CAS No. 85-68-7) Administered in Feed to CD Rats on Gestational Days 6 to 15

NTP Study: TER88025

ABSTRACT

Butyl benzyl phthalate (BBP), a phthalate ester plasticizer, was evaluated for maternal and developmental toxicity in timed-pregnant Sprague-Dawley derived (CD) rats (27-30/group). BBP (0, 0.5, 1.25 or 2.0%) in feed between the mornings of gestational day (gd) 6 and 15 yielded average doses of 0, 0.42, 1.10 or 1.64 g BBP/kg/day, respectively. At sacrifice (gd 20), 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 0.5% BBP other than increased relative water intake (g/kg/day) between gd 15 and 18. Dams in the 1.25% BBP group exhibited a 37% reduction in weight gain during treatment, increased relative liver wt., increased relative food intake (11-25% after gd 12), and increased relative water intake (18-41% after gd 9). At 1.25% BBP, the percent fetuses with variations/litter was increased, and the percent fetuses malformed/litter (5.9% vs. 2% for controls) approached statistical significance. Dams in the 2% BBP group showed a 93% reduction in treatment weight gain, and a 17% reduction in corrected weight gain. Relative liver and kidney weights were increased. Relative food intake was initially decreased (14% for gd 6 to 9), and later increased (16-44% after gd 12). Relative water intake was increased (25-73% after gd 9). At 2% BBP, the resorptions/litter were increased (40% vs. 4% for controls), average fetal body weight/litter was reduced by 20%, and the percent malformed fetuses/litter was increased (53% vs. 2% for controls).

In summary, 0.5% dietary BBP was a no-observed-adverse-effect level (NOAEL) for both maternal and developmental toxicity. The mid-dose (1.25% BBP) produced significant maternal toxicity and minimal evidence of developmental toxicity. At the high dose (2% BBP), significant maternal and developmental toxicity was observed, including an increased incidence of malformations.

Report Date: August 4, 1989

NTIS# PB90-115346/AS

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