Subchronic toxicity study of ferric oxide nanoparticles through intragastric administration: A 94-d, repeated dose...

In this study, the toxicity of ferric oxide nanoparticles (Fe₂O₃ NPs) administered through gavage to Sprague Dawley (SD) rats for 94 d, consecutively and the recovery after Fe₂O₃ NPs withdrawal for 30 d were evaluated. The vehicle control group, low-, medium-, and high-dose groups were administered with the vehicle (0.5% sodium carboxymethyl cellulose [CMC-Na]), 125, 250, and 500 mg/kg of Fe₂O₃ NPs, respectively, administered every morning for 94 d. There was no significant difference in the body weight, food intake, hematological, blood biochemical, and urine indices of SD rats in each administration group and the control group (P > 0.05). There was no significant difference in organ weight, organ indices, and the coefficient of the visceral brain between the SD rats in the different dosage groups and the SD rats in the vehicle control group (P > 0.05). Histopathological observations showed that there was no correlation between the pathological lesions of the organs observed in this study and the dose of Fe₂O₃ NPs (P > 0.05). The no-observed-adverse-effect level (NOAEL) dose of Fe₂O₃ NPs was initially determined to be 500 mg/kg administered to SD rats through oral gavage for 94 d, consecutively, followed by recovery after Fe₂O₃ NPs withdrawal for 30 d.