Comparative analysis of the toxicological and histopathological impact of microplastic fibers and microbeads in exposure associated with dibutyl phthalate in zebrafish (Danio rerio)

Acting as emerging pollutants in freshwater ecosystems, microplastics and plasticizers may have toxicological and histopathological effects on aquatic organisms. However, the combined toxicity of microplastics and plasticizers as well as the toxicological differences among various microplastic shapes have been limitedly studied. To address these gaps, we conducted laboratory experiments using zebrafish (Danio rerio, Hamilton 1822) to assess oxidative stress levels, lipid peroxidation, and pathological damage under both sole and combined exposure to microplastic fibers (MFs), microbeads (MBs), and dibutyl phthalate (DBP). Generally, our results demonstrated significantly toxicological response of fish livers and intestines to the sole and combined exposure to microplastics (MFs and MBs) and DBP. Specifically, in fish livers, MFs accounted for the highest increase in CAT and GST activity, with more severe swollen hepatocytes and vacuolization occurred. Similarly, we also recorded higher SOD activity and MDA content with the exposure to MFs in zebrafish intestines. In addition, the exposure to MFs incurred more severe changes in goblet cell reduction and hypervacuolisation in fish intestines. In summary, MFs exhibited more severe oxidative stress and pathological damage than MBs, which highlighted the importance of prioritizing MFs in environmental monitoring and examining the toxicity of MFs on laboratory studies.