1. Investigation of pulmonary inflammatory responses following intratracheal instillation of and inhalation exposure to polypropylene microplastics
- Author
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Taisuke Tomonaga, Hidenori Higashi, Hiroto Izumi, Chinatsu Nishida, Naoki Kawai, Kazuma Sato, Toshiki Morimoto, Yasuyuki Higashi, Kazuhiro Yatera, and Yasuo Morimoto
- Subjects
Microplastics ,Polypropylene ,Inhalation exposure ,Intratracheal instillation ,Pulmonary toxicity ,Rat ,Toxicology. Poisons ,RA1190-1270 ,Industrial hygiene. Industrial welfare ,HD7260-7780.8 - Abstract
Abstract Background Microplastics have been detected in the atmosphere as well as in the ocean, and there is concern about their biological effects in the lungs. We conducted a short-term inhalation exposure and intratracheal instillation using rats to evaluate lung disorders related to microplastics. We conducted an inhalation exposure of polypropylene fine powder at a low concentration of 2 mg/m3 and a high concentration of 10 mg/m3 on 8-week-old male Fischer 344 rats for 6 h a day, 5 days a week for 4 weeks. We also conducted an intratracheal instillation of polypropylene at a low dose of 0.2 mg/rat and a high dose of 1.0 mg/rat on 12-week-old male Fischer 344 rats. Rats were dissected from 3 days to 6 months after both exposures, and bronchoalveolar lavage fluid (BALF) and lung tissue were collected to analyze lung inflammation and lung injury. Results Both exposures to polypropylene induced a persistent influx of inflammatory cells and expression of CINC-1, CINC-2, and MPO in BALF from 1 month after exposure. Genetic analysis showed a significant increase in inflammation-related factors for up to 6 months. The low concentration in the inhalation exposure of polypropylene also induced mild lung inflammation. Conclusion These findings suggest that inhaled polypropylene, which is a microplastic, induces persistent lung inflammation and has the potential for lung disorder. Exposure to 2 mg/m3 induced inflammatory changes and was thought to be the Lowest Observed Adverse Effect Level (LOAEL) for acute effects of polypropylene. However, considering the concentration of microplastics in a real general environment, the risk of environmental hazards to humans may be low.
- Published
- 2024
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