Potential toxic effects of polylactic acid microplastics accumulation on multiple tissue structures and hematology in...

Microplastics (MPs) are widespread environmental pollutants that pose threats to animal survival, biodiversity, and potentially, ecosystem security and human health. Polylactic acid (PLA) MPs are important bio-based biodegradable plastic and also a research target for environmental issues. In this study, a PLA-MPs exposure model of common carp (Cyprinus carpio, hereafter, "carp") was established from a new perspective in order to explore the distribution of PLA-MPs in carp and its influence on histological structure and hematological parameters. One hundred and sixty carp (mean weight 264.14 ± 8.47 g, mean length 27 ± 2.61 cm) were randomly divided into two groups: a control group (CON) and a group exposed to 5 mg/L PLA-MPs (PLA). The results demonstrated that exposure to this concentration led to the retention of PLA-MPs in multiple organs. The residue levels, in descending order, were: intestine > gills > muscle > liver > skin > kidney. Exposure to 5 mg/L PLA-MPs caused structural damage to these organs, for example, marked cellular vacuolization and mitochondrial damage were observed. Serum biochemical indexes and metabolomics analysis revealed that PLA-MPs exposure had significant adverse effects on the blood characteristics of carp. The results of this study provide a theoretical basis for revealing the toxic effects of PLA-MPs from a new perspective.