Evaluation of the Toxicity, Alveolar Cell Accumulation and Clearance of PET and PS Nanoplastics in Mouse Lungs

Airborne micro and nano-plastics (MNPs) have been detected in both indoor and outdoor settings, raising concerns about potential adverse effects upon inhalation. Yet, their potential pulmonary toxicity has not been studied extensively. Herein, we evaluated the pulmonary toxicity and clearance of nanometric Poly-Ethylene Terephthalate (PET; ~50-200 nm) fragments from plastic bottles and two nanometric polystyrene (PS; 50 and 200 nm) beads. Adult mice were exposed to a unique dose of 50 ug in 30uL/mouse of PET, PS-50, PS-200, or vehicle by pharyngeal aspiration. The lungs, broncho-alveolar lavage fluids (BALF) and lymph nodes were collected at 1, 7 and 28 days after exposure. MNPs presence in lung tissue, accumulation in alveolar cells, and clearance from the alveolar cavity and lungs were assessed using confocal Raman microscopy (CRM). Inflammation and tissue damages were evaluated by histology, immunostaining and ELISA. PET and PS nanoplastics were detected by CRM in lungs and alveolar phagocytes. Evaluation of MNPs elimination and translocation to lymph nodes is underway. Pulmonary exposure to MNPs induced immune cell infiltration respective of MNP type or size. Recruitment of neutrophils at day 1 and eosinophils at day 7 was more pronounced for the PS-50 than for the other two MNPs. Recruitment of lymphocytes was noted at day 7, yet only for PS-50 nm. Potential long-term impact (genotoxicity, fibrosis) is under investigation. These results will inform the design of future chronic low-dose exposure studies, and path the way to new policies about the impact of MNPs on human health.