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EC number: 500-209-1 | CAS number: 68412-54-4 1 - 2.5 moles ethoxylated
Male and female Mol:WIST rats, 11 weeks of age, were mated. Mated females received NPE-9 (commercial formulation with an average ethoxylation grade of 9) by gavage (0, 50, 250 and 500 mg/kg bw/day) or skin application (0, 50 and 500 mg/kg bw/day) from Gestation Day 6 - 15 or 1 -20 (only 500 mg/kg bw/day per oral). Mated females were weighed on Days 1, 6, 9, 12, 15 and 21. On Day 21, the rats were sacrificed and necropsied. The following parameters were recorded: weight of the intact uterus and ovaries, number of corpora lutae, implantation and fetuses, live and dead. The fetuses were weighed, their sex determined and they were examined for gross external malformations. Half of the fetuses were examined for skeletal abnormalities. The remaining fetuses were fixed in Bouins solution and sectioned. Weight of dams, sex ration of fetuses and pre- and post-implantation losses were calculated.
The dams given 250 mg NPE-9/kg bw/day orally on Days 6-15 and 500 mg/kg bw/day on Days 6-15 and 1-20 exhibited a statistically significant decrease in weight gain. A concomitant decrease in food consumption was observed in dams exposed to 500 mg/kg bw/day as compared to controls. All rats given epicutaneous doses, including controls, exhibited a marked decrease in bodyweight and weight gain during the treatment. Sporadic, not dose-related, changes in reproduction parameters were observed in the rats treated orally with NPE-9. A slight, but statistically significant, lower average litter size was observed at 250 mg/kg bw/day and an increase in pre-implantation loss at 250 and 500 (Days 6-15) mg/kg bw/day. The animals given the highest epicutaneous dose exhibited higher reproduction as compared to controls (increased litter size and decreased post-implantation loss). In rats given NPE-9 orally, a statistically significant dose-related increase in extra ribs and rudiments of ribs was noted. In addition, an increased incidence in fetuses showing slightly dilated pelvic cavity was observed at 500 mg/kg bw/day (Day 1 - 20). When given epicutaneously, NPE-9 had no effects on skeletal and solt tissues. An increased incidence of extra ribs was seen at 50 mg/kg bw/day but not at 500 mg/kg bw/day (epicutaneous).
Under the study conditions, the NOEL for NPE-9 was 50 mg/kg bw/day (Days 6 -15) when given orally. Higher doses exerted reproductive toxicity effects probably due to maternal toxicity. Epicutaneous doses of NPE-9 had no effect (Meyer et al., 1988).
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