Microplastics and nanoplastics (MNPs) are emerging environmental contaminants with potential systemic health effects. Urine offers a non-invasive, repeatable matrix for exposure assessment, yet scalable detection methods remain limited. In this preliminary study, spiked human urine samples were analyzed using a non-destructive optical imaging and computational analysis workflow. Reproducible differences in spatial heterogeneity, aggregation behavior, and temporal evolution were observed, with nanoplastic conditions showing earlier and more pronounced organization at low concentrations. These findings demonstrate feasibility of detecting both micro- and nanoplastic-associated signals in intact biological fluids and support further development of scalable, urine-based monitoring approaches. Keywords: microplastics, nanoplastics, urine, optical imaging, scalable detection, biomonitoring