Visible Combined\nNear-Infrared <i>in Situ</i> Imaging Revealed Dynamic Effects\nof Microplastic Fibers and Beads\nin Zebrafish

Microplastics (MPs) as emerging contaminants are widely\npresent\nin the environment and are ubiquitously ingested and accumulated by\naquatic organisms. MPs may be quickly eliminated after a brief retention\nin aquatic animals (such as the digestive tract); thus, understanding\nthe damage caused by MPs during this process and whether the damage\ncan be recovered is important. Here, we proposed the use of visible\nlight imaging to track MPs combined with near-infrared (NIR) imaging\nto reveal the <i>in situ</i> impacts of MPs. The combination\nof these two techniques allows for the simultaneous investigation\nof the localization and functionality of MPs <i>in vivo</i>. We investigated the effects of two types of MPs on zebrafish, microplastic\nfibers (MFs) and microplastic beads (MBs). The results showed that\nMPs larger than 10 μm primarily accumulated in the intestines\nof zebrafish. Both MFs and MBs disrupted the redox balance of the\nintestine, and the location of the damage was consistent with the\nheterogeneous accumulation of MPs. MFs caused greater and more difficult-to-recover\ndamage compared to MBs, which was closely related to the slower elimination\nrate of MFs. Our study highlights the importance of capturing the\ndynamic toxicological effects of MPs on organisms. Fibrous MPs and\nspherical MPs clearly had distinct effects on their toxicokinetics\nand toxicodynamics in fish.