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Size-Dependent Pulmonary Toxicity and Whole-Body Distribution of Inhaled Micro/Nanoplastic Particles in Male Mice from Chronic Exposure

Environmental Science & Technology 2025 21 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Leijian Chen, Yu Liu, Huankai Li, Siyi Lin, Xiaoxiao Wang, Jiacheng Fang, Xin Diao, Lei Wang, Zhu Yang, Zongwei Cai

Summary

Researchers exposed mice to airborne micro- and nanoplastic particles through normal breathing over an extended period and found the highest accumulation in the lungs, followed by the blood and spleen. Surprisingly, the larger 1-micrometer microplastics caused more severe lung damage than the smaller 80-nanometer particles, triggering inflammation, cell death, and scarring. These findings highlight that breathing in airborne plastic particles poses real health risks, with particle size playing an important role in the type of damage caused.

The ubiquitous presence of micro/nanoplastics (MP/NP) in the atmosphere has raised significant concerns about their potential health risks through inhalation, yet the effects of natural respiratory exposure remain underexplored. This study addresses this critical knowledge void by utilizing a whole-body inhalation exposure system to investigate the distribution, accumulation, and pulmonary toxicity of polystyrene MP/NP (1.5 × 105 particles/m3) in male ICR mice (n = 16/group). Fluorescently labeled MP/NP revealed the highest particle accumulation in the lungs, followed by the bloodstream and spleen, with minimal detection in the brain. Unsurprisingly, 80 nm nanoplastics displayed greater intertissue transport efficiency than 1 μm microplastics. Chronic exposure to both microplastics and nanoplastics disrupted oxidative balance and exacerbated oxidative stress within the extracellular environment of the lungs. The impaired antioxidant defenses and disrupted intra- and extracellular metabolism led to inflammation, apoptosis, and fibrosis. Intriguingly, 1 μm microplastics induced more severe pulmonary toxicity than their smaller counterparts, promoting epithelial-mesenchymal transition and fibrosis. These findings underscore the need for a nuanced understanding of size-dependent toxicities of inhalable plastic particles and highlight the health risks posed by airborne MP/NP.

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