Respiratory Toxicity of Short and Long Silver Nanowires in Rats
Kian Fan Chung, M.D., Junfeng Zhang, Ph.D., Alexandra Porter, Ph.D.
Duke University, University of Southern California
NIEHS grantees report that cells in the lungs of rats converted short and long silver nanowires into shorter lengths that were fully taken up by lung cells and led to lung inflammation. The study provides new insights into possible health risks linked with silver nanomaterials, which are increasingly used in industrial and domestic products, such as odor-resistant socks, personal care products, respiratory devices, food storage boxes, computers, and cleaning sprays.
To study the respiratory toxicity of short and long silver nanowires — 1.5 microns and 10 microns in length, respectively — the researchers instilled nanowires of each length into the lungs of rats. Within one day of instillation, both short and long nanowires were taken up and degraded by lung macrophages, a type of white blood cell that engulfs and digests cellular debris, and by cells lining lung alveoli, the site of oxygen exchange. Using three-dimensional scanning electron microscopy, the researchers observed a small, but significant, reduction of nanowire lengths inside cells.
The researchers also observed increased lung inflammation after instillation of both types of nanowires. Mice receiving the long nanowires showed a greater and longer-lasting degree of lung inflammation and bronchial hyperreactivity.
Citation: Chung KF, Seiffert J, Chen S, Theodorou IG, Goode AE, Leo BF, McGilvery CM, Hussain F, Wiegman C, Rossios C, Zhu J, Gong J, Tariq F, Yufit V, Monteith AJ, Hashimoto T, Skepper JN, Ryan MP, Zhang J, Tetley TD, Porter AE. 2017. Inactivation, clearance, and functional effects of lung-instilled short and long silver nanowires in rats. ACS Nano 11(3):2652-2664.
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