Recent studies have accelerated understanding of micro- and nanoplastic contamination in diverse environments and biological systems. Researchers have developed novel analytical techniques such as AI-driven sensors, nuclear magnetic resonance spectroscopy, and dielectrophoresis combined with Raman spectroscopy to detect and quantify micro- and nanoplastics in water, soil, river basins, and even human feces and blood. Concerns are mounting regarding the biological impact, exemplified by studies showing nanoparticle effects on gut cells and neurons, and the identification of tire wear particles as a significant terrestrial pollutant. The Lancet Countdown on Health and Plastics highlights the urgent need to track plastic pollution’s hidden threats to human well-being amidst ongoing international treaty discussions.