Gestational Intranasal Exposure to Silicon Dioxide Nanoparticles in Rats

Background: Silicon dioxide nanoparticles (SiO 2 NPs) are among the most widely manufactured nanomaterials, used in diverse industrial, pharmaceutical, and consumer products. Although the respiratory tract represents one of the major routes of human exposure, the potential reproductive and developmental toxicity of SiO 2 NPs via respiratory exposure remains poorly characterized. Methods: This study investigated the maternal and developmental toxicity of SiO 2 NPs in pregnant Sprague-Dawley rats. Pregnant animals were intranasally administered SiO 2 NPs once daily during gestation day (GD) 6 to 20 at doses of 0, 2, 6, and 20 mg/animal, followed by caesarean section on GD 21. Results: Treatment-related changes were observed in the respiratory tract, appearing as mild inflammatory and regenerative alterations. No mortality or systemic maternal toxicity was observed, and evaluation of caesarean section parameters and fetal morphology demonstrated no evidence of adverse developmental effects. Conclusion: Repeated intranasal exposure to SiO 2 NPs during pregnancy induced localized histopathological changes in the respiratory tract, with no evidence of systemic maternal or embryo-fetal toxicity at the assessed endpoints under the present experimental conditions. These findings provide experimental data relevant to the assessment of respiratory exposure to SiO 2 NPs during pregnancy; however, further studies are warranted considering the diverse properties of nanoparticles and the potential for varied exposure scenarios.