Three-dimensional Tracking of Microplastics in Zebrafish Using micro-Computed Tomography

Understanding the fate of microplastics after ingestion is essential for assessing their biological effects, yet tracking these particles within organisms remains a major analytical challenge. The conventional detection methods often lack the information about spatial distribution due to destructive sample preparation methods. This study presents a novel, non-destructive micro-computed tomography (microCT) methodology for realistic three-dimensional tracking of microplastics in zebrafish. Using a feeding-based exposure design, ingestion, distribution, and elimination of aged polyethylene microplastics within the gastrointestinal tract were visualized over time. Two complementary exposure approaches, continuous and short-term, were applied to simulate environmentally relevant conditions and to assess microplastic movement through the gut. The results confirmed voluntary ingestion of microplastics and revealed their progressive passage toward the posterior intestine, allowing visualization of elimination kinetics and estimation of particle retention within different gut regions. Continuous exposure reflected cumulative ingestion patterns typical of persistent environmental conditions, whereas short-term exposure provided clearer resolution of microplastic transit dynamics. The developed methodology provides a realistic, reproducible, and non-destructive framework for tracking microplastics within intact aquatic organisms. It enables direct visualization of post-ingestion processes and supports future research on microplastic post-ingestion behaviour, revealing where microplastics accumulate, consequently allowing to better understand the potential biological effects in ecotoxicological contexts.