Developmental toxicity of di-(C(7)-C(9) alkyl) phthalate and di-(C(9)-C(11) alkyl) phthalate in the rat

Two phthalate esters, di-(C(7)-C(9) alkyl) phthalate (D79P) and di-(C(9)-C(11) alkyl) phthalate (D911P), have been assessed for their potential to cause developmental toxicity in the rat. Groups of 22 timed-mated Sprague-Dawley rats were administered 250, 500, or 1000 mg/kg D79P or D911P daily by oral gavage (5 ml/kg) between gestation days (GD) 1 and 19. Control animals received the vehicle (olive oil) alone. On GD20, the animals were sacrificed and the fetuses examined. Treatment resulted in no signs of maternal toxicity, as assessed by adjusted maternal bodyweight gain throughout gestation and clinical examinations, and no effects upon litter size, fetal survival or bodyweight. Pups of the high dose D79P and intermediate and high dose D911P groups showed increased incidences of supernumerary lumbar ribs. There was a significant increase in dilated renal pelves in pups of the low dose D79P and high dose D911P groups, but only for D911P was there a significant trend. Consequently, the no observed adverse effect level (NOAEL) for maternal toxicity for both D79P and D911P is 1000 mg/kg/day. The NOAEL values for developmental toxicity are 500 mg/kg/day D79P and 250 mg/kg/day D911P.