In vivo toxicity, with immunodysregulatory potentials, of polytetrafluorethylene nanoplastics to rats administered intragastrically for 90 d

Polytetrafluorethylene (PTFE), also known as Teflon, constitutes the most utilized fluoropolymer and comprises approximately 60% of the total international fluoropolymer market. The aim of the present study was to assess the oral toxicity attributed to exposure to 260 nm PTFE-nanoparticle (NPs) in Sprague-Dawley rats following OECD TG 408 guidelines. Over a 90-d period, rats received daily doses of 250, 500, or 1000 mg/kg, representing low, intermediate, and high exposure levels, to determine the influence of the NPs. There were no specific clinical signs associated with PTFE NP administration, as determined by general and detailed clinical observations, ophthalmology, and functional observational battery. No significant alterations related to PTFE-NP administration were detected by hematology, urinalysis, or clinical biochemistry, except that dose-dependently higher levels of serum aspartate aminotransferase, blood urea nitrogen, and triglyceride were observed in males, all within the normal range. There were no abnormalities in gross necropsy, no alterations in organ weights, and no histopathological changes in any PTFE-NP‑administered group for either gender, except for more pituitary cysts and ultimobranchial body cysts in the male high‑dose group. Considering no significant differences in other hepatic or renal function biomarkers and no abnormalities in hepatic or renal histopathology in high‑dose males, those changes were considered unrelated to PTFE-NP administration. Administration of PTFE-NPs preferentially suppressed type-1 helper T cell reactivity, most notably in females, and a downregulation of age-dependent increase of serum IgG levels, regardless of gender. Overall, based upon our findings, the no-observed-adverse-effect level is estimated at 1000 mg/kg body weight or less for both genders.