Teratogenic evaluation of a polybromodiphenyl oxide mixture in New Zealand white rabbits following oral exposure.

Polybromodiphenyl oxide (PBDPO), a potential flame retardant additive in thermoplastics and thermosets, was tested for its embryo/fetal toxicity and teratogenicity in pregnant rabbits. PBDPO was orally administered to groups of 26 New Zealand White rabbits at dose levels of 0 (corn oil, vehicle control), 2, 5, or 15 mg/kg/day in a dose volume of 1 ml/kg body weight on Days 7 through 19 of gestation. The offspring were then examined on Day 28 of gestation. No evidence of teratogenicity was observed at any dose level tested. Pregnant rabbits in the 15 mg/kg/day dose group showed evidence of maternal toxicity as exhibited by significant increases in absolute and relative liver weights and decreased body weight gain during gestation Days 7 through 20 and Days 7 through 28. Slight fetal toxicity accompanied the maternal toxicity at the high dose level, as demonstrated by an increase in the incidence of delayed ossification of the sternebrae.