122 Elucidating the Impact of Inhaled Micro-, Nanoplastics (MNPs) from Surgical Face Masks In Vitro

Abstract Surgical face masks are routinely used in clinical settings, but also extensively by the public during the SARS-CoV-2 pandemic. These masks contain a high proportion of plastic, specifically polypropylene (PP), which could shed microscopic particles to the environment or nasal cavity. However, to-date, despite focus upon an increased environmental burden, the (human) hazard relevant to inhaled MNPs remains largely unknown. The aim of this project therefore, was to determine the toxicity of inhaled PP (commercially available powders, or extracted from surgical masks; either (i) all layers, or (ii) the innermost layer only), using an advanced in vitro approach. Type-II lung epithelial cells (NCI-H441) were cultured at the air-liquid interface and exposed to respirable PP via aerosol for 24hrs at depositions of 500, 100 and 2000 ng/cm2 (Vitrocell Cloud12). Carbon black (Printex 90) was used as a positive particle control. Respirable MNP samples required cryomilling and cryotome slicing, and were analysed using pyrolysis-GCMS. In addition to acellular deposition, as well as particle and cellular morphology (electron microscopy) assessed endpoints of cytotoxicity (trypan blue exclusion), barrier integrity (dextran blue), (pro-)inflammatory response (IL-1β/IL-6/IL-8), oxidative stress (SOD-1), and genotoxicity (mononucleate micronucleus) were conducted. So far, a concentration-dependent decrease in cell viability was observed following exposure to commercial PP and complete mask PP samples, whilst a concentration-dependent increase in all (pro-)inflammatory mediators assessed was noted. Further, initial genotoxicity assessment suggests a minor increase to micronucleus formation for both exposure samples. Preliminary data therefore suggests that aerosolised MNPs instigate a hazardous response in vitro.