Tiny plastic particles, from the micro- to nanoscale, have been routinely detected in water, soil, air, aquatic species, and humans in recent years. As concerns grow over their potential impact on the environment and human health, researchers are working to uncover just how toxic these plastics can be in living systems.
While studies have examined plastic pollution in marine environments—showing how microplastics infiltrate aquatic species, accumulate in gills, and trigger cellular damage and immune responses—many questions remain about their effects on cell and tissue health.1
Bioinformatician Yun Hak Kim from Pusan National University investigates how polystyrene nanoparticles, commonly found in disposable bags and bottle caps, affect red blood cell (RBC) development in zebrafish. In his new study published in Zoological Research, he and his team found that nanoparticles disrupted normal RBC development in zebrafish.2 This led to increased immature RBCs with lower heme content, likely impairing oxygen transport. The findings highlight the harmful effects of nanoplastics on zebrafish and emphasize the need for more rigorous research into their broader ecological and health consequences.
To investigate the effects of polystyrene nanoparticles in zebrafish, the researchers exposed fully hatched zebrafish, at 72 hours post-fertilization, to polystyrene nanoparticle solutions. The concentrations ranged from 0.1 to 10µg/mL to reflect levels found in natural water and marine environments.3
Zebrafish larvae exposed to 10µg/mL of polystyrene nanoparticles showed significant accumulation in the gut but exhibited no severe morphological changes. However, microscopic imaging revealed subtle effects, including increased eye distance and an elevated heart rate.
To investigate further, the team compared the cell populations of control and nanoparticle-exposed zebrafish and found a notable decrease in the RBC population within the treated fish, suggesting disrupted RBC production. The team confirmed these by injecting fish with an o-dianisidine stain to visualize hemoglobin-containing cells such as RBCs.
The researchers also noted that the reduced RBC population contained a higher proportion of immature blood cells, which carry less oxygen. Using single-cell RNA sequencing, they observed that polystyrene nanoparticles also disrupted heme synthesis by down-regulating key genes, weakening RBCs' oxygen-carrying power. These findings were confirmed using mass spectrometry, which detected a significant reduction in hemin, the final byproduct of heme, in exposed zebrafish.
Not only was heme affected, but the researchers also saw decreased expression of translation-related pathways within RBC development, notably in the ribosomal protein S7 gene (rps7). To confirm rps7’s role, the team conducted knockdown experiments, which resulted in a reduction in RBCs in zebrafish. These results suggest polystyrene nanoparticles disrupt the protein synthesis machinery essential for RBC development in zebrafish.
“As we learn more about the biological effects of nanoplastics, it becomes essential to rethink plastic waste management and explore safer materials,” said Kim in a press release.
- Timilsina A, et al. Effects of microplastics and nanoplastics in shrimp: Mechanisms of plastic particle and contaminant distribution and subsequent effects after uptake. Sci Total Environ. 2023;894:164999.
- Kwon EJ, et al. Deciphering the toxic effects of polystyrene nanoparticles on erythropoiesis at single-cell resolution. Zool Res. 2025;46(1):165-176.
- Wang W, et al. Nanoplastic exposure at environmental concentrations disrupts hepatic lipid metabolism through oxidative stress induction and endoplasmic reticulum homeostasis perturbation. Environ Sci Technol. 2023;57(38):14127-14137.
