The substitution of petrochemical plastics by bio-based and biodegradable plastics are in need of an evaluationfor the potential toxic impacts that they can have on marine wildlife. This study aims to assess the toxicologicaleffects of polylactic acid microparticles at two concentrations, 10 and 100 μg/L, during 8 days on the bluemussel, Mytilus edulis. No significant oxidative stress (catalase, glutathione-S-transferase and superoxide dismutase activities), neurotoxicity (acetylcholinesterase), or immunotoxicity (lysosomal membrane stability andacid phosphatase activity) were detectable. The multivariate analysis of metabolomic data allowed us todifferentiate the individuals according to the exposure. From the loading plot of OPLS-DA, 48 ions downregulated in the individuals exposed to microplastics. They were identified based on HRMS data asglycerophospholipids.