Strain-Specific Toxicity of Polylactic Acid Biomicroplastics in Mice: Insights Into Liver and Intestine Responses

Although the toxicity of petroleum-based microplastics (MPs) in different organisms is already known, the effects of alternative biopolymers on mammals remain poorly understood. Thus, we aim to evaluate the possible effects of long-term ingestion of biomicroplastics of polylactic acid (BioMPs-PLA) by mice of different strains. Female Swiss and C57Bl/6J mice received a daily oral dose of 9.6 mg BioMPs-PLA/kg (equivalent to 6.8 × 10 6 particles/kg) for 50 days. Exposure to biopolymers did not induce locomotor changes, anxiety-like behavior, memory deficit, reduction in body biomass, changes in feed and water intake, or an increase in lipid peroxidation processes and changes in IL-10 levels in the liver and intestine of animals. However, through principal component analysis (PCA), hierarchical cluster analysis and the Integrated Biomarker Response index (IBRv2), we showed that BioMPs-PLA induced a strain-dependent response, being more toxic to C57Bl/6J mice. This was determined by increased SOD activity and production of nitrite, IFN-[Formula: see text] and ROS in the intestine and suppression of DPPH radical scavenging activity in the liver. In Swiss mice, toxicity was determined by SOD activity and inhibition of INF-[Formula: see text] and nitrite production in the liver and suppression of SOD activity in the intestine. BioMPs-PLA induced greater liver toxicity in Swiss mice, while the intestinal response was more pronounced in C57Bl/6J mice. Our study demonstrates that BioMPs-PLA can be toxic to mammals, challenging the notion that bioplastics are harmless. Furthermore, our findings emphasize the need for further research with varied doses, exposure times and comprehensive analyses to understand the dynamics and mechanisms of BioMPs-PLA toxicity fully.