Size-dependent toxicity of microplastics and nanoplastics: insights from the Drosophila melanogaster model

Microplastics and nanoplastics (MNPs) are ubiquitous environmental pollutants that enter organisms and induce multi-system damage. Particle size is a critical determinant of MNPs’ bioavailability, biodistribution, and toxic intensity, with smaller particles exhibiting stronger biopermeability and toxic hazards. Drosophila melanogaster (fruit fly) has emerged as an ideal model organism for investigating MNPs’ toxic mechanisms due to its short life cycle, clear genetic background, and high genetic homology with humans.This review systematically summarizes research on the toxicity of MNPs with different sizes based on the Drosophila model, clarifying the size-dependent toxicity pattern. Large microplastics (1–5 mm) remain in the digestive tract, causing local physical damage and dysbiosis. Small microplastics (1 μm–1 mm) induce intestinal damage, oxidative stress, as well as abnormalities in behavior and reproduction. Submicroplastics (100 nm–1 μm) can penetrate the intestinal barrier, triggering systemic inflammation and cardiac dysfunction. Nanoplastics (