P22-20 Evaluating the pulmonary toxicity of nanocellulose as a promising alternative to plastic

With growing concern over plastic pollution, biodegradable polymers have gained attention as sustainable alternatives. Among them, nanocellulose – cellulose fibers with at least one dimension under 100 nm – has emerged as a strong candidate to replace conventional plastics due to its biodegradability, renewability, and ease of chemical modification. However, its nanoscale size raises concerns about potential health risks, particularly through inhalation, which has not been thoroughly studied. In this study, we assessed the respiratory toxicity of five types of nanocellulose derived from different raw materials and processing methods. We conducted both in vitro experiments using lung epithelial and macrophage cell lines, and in vivo studies through intratracheal instillation in mice. The in vitro results showed no evidence of cytotoxicity, oxidative stress, or inflammatory responses. In contrast, in vivo exposure led to noticeable inflammatory cell infiltration and histopathological changes in lung tissues. Notably, microfibrillated cellulose (MFC) produced from hardwood kraft pulp via high-pressure homogenization significantly increased eosinophil infiltration in mouse lungs. This response suggests a potential to trigger allergic reactions associated with asthma. While a full risk assessment requires accurate data on human inhalation exposure levels, our findings indicate that, despite its promise as a sustainable plastic alternative, this study suggests that nanocellulose may pose respiratory health risks under certain conditions. Funding: This research was supported by the Korea Planning & Evaluation Institute of Industrial Technology (KEIT) through the Project for technology development and corporate support for nanoproduct performance safety evaluation, funded by the Korea Ministry of Trade, Industry and Energy (RS-2024-00466969) and the Korea Institute of Toxicology (grant no. TS-2501).