Polylactic Acid Microplastics Do Not Exhibit Lower Biological Toxicity in Growing Mice Compared to Polyvinyl Chloride Microplastics

Biomicroplastics (BMPs) will be produced during bioplastic degradation (i.e., polylactic acid), although bioplastics have been widely used for food packaging. Like conventional microplastics (MPs), BMPs would be mistakenly ingested into the body through diet or drinking water, but their health risks in vivo are poorly understood. Here, we deeply compared the toxicity difference between irregularly shaped polylactic acid (PLA-MPs, 16-350 μm) and polyvinyl chloride (PVC-MPs, 40-300 μm) MPs in growing mice. After six weeks of exposure, PLA-MP exposure resulted in more severe inhibition of the mice's weight gain than PVC-MPs did. Both PLA- and PVC-MPs significantly elevated the levels of oxidative stress. Moreover, significant changes including altered transcriptional profiles and significantly differentially expressed genes in liver and colon transcription levels were observed in the PVC- and PLA-MP groups. Compared with PVC-MPs, PLA-MPs have a stronger effect on lipid metabolism and digestive systems. PLA-MPs also caused gut microbiota dysbiosis, significantly interfering with the relative abundance of microbiota and altering microbial diversity. These findings indicated the toxicities of PLA-MPs in growing mice were not significantly reduced compared to PVC-MPs, which would also provide new insights for re-examining bioplastic safety.