Toxicity study of silica nanoparticles following 94-day repeated oral administration in Sprague Dawley rats

This study was designed to investigate the toxic response of Sprague Dawley (SD) rats following oral administration of different doses of silica nanoparticles (SiNPs) for 94 consecutive days, as well as the recovery after 30 days of withdrawal. Rats were orally administered SiNPs at dosages of 0, 125, 250, and 500 mg/kg /day once a day for 94 continuous days. By the end of the study, there were no fatalities in any of the experimental animals that received SiNPs orally. Under the tested doses, no adverse effects related to SiNPs treatment were observed in a comprehensive assessment of several dimensions, including clinical signs, body weight changes, food consumption, hematological parameters, blood biochemical indices, urinalysis, organ weights and coefficients, and gross and histopathology. Based on the current study results, the No Observed Adverse Effect Level (NOAEL) for repeated oral administration of SiNPs in rats for 94 consecutive days was designated as 500 mg/kg/day.