DEVELOPMENTAL TOXICITY OF EXELL(R), A SURFACTANT MIXTURE IN RATS AND RABBITS

A surfactant mixture (C.A.S No. 104559-06-2), is used in combination w ith foliar-acting herbicides to improve herbicidal performance by incr easing plant uptake. It was administered by gavage as an aqueous solut ion to groups of 25 assumed pregnant Crl:CD(R)BR rats from Days 7-16 o f gestation at daily dosage levels of 0, 3, 8, 20, or 50 mg/kg body we ight. The dams were euthanized on Day 22 of gestation and the offsprin g were weighed and examined for external, visceral, and skeletal alter ations. The surfactant mixture was maternally toxic at levels of 20 mg /kg/day and above as evidenced by reduced maternal weight gain and by an increased incidence of lung noise (wheezing and/or rattling) and sn eezing. In addition, maternal food consumption was reduced in the high dosage group. There was no evidence of developmental toxicity at any dosage level. In the rabbit study, groups of 20 artificially inseminat ed adult Hra:(NZW)SPF rabbits were similarly dosed from Days 6-18 of g estation at daily dosage levels of 0, 12, 35, or 100 mg/kg body weight . The does were euthanized on Day 29 of gestation and the offspring we re weighed and examined for external, visceral, and skeletal alteratio ns. Dosages of 35 and 100 mg/kg/day resulted in reduced maternal body weight gain, food consumption and fetal body weight. Thus, in the rat, the maternal and developmental no-observed-adverse-effect levels (NOA ELs) were 8 mg/kg/day and greater than 50 mg/kg/day, respectively. In the rabbit, the maternal and developmental NOAELs were 12 mg/kg/day. T his surfactant mixture was, therefore, not demonstrated to be uniquely toxic to either the rat or rabbit conceptus.