Uptake and effects of microplastics on cells and tissue of the blue mussel Mytilus edulis L. after an experimental exposure

In this study, we investigated if industrial high-density polyethylene(HDPE) particles, a model microplastic free of additives, ranging < 0−80 μm are ingested and taken up into the cells and tissue of the blue musselMytilus edulis L. The effects of exposure (up to 96 h) and plastic ingestion wereobserved at the cellular and subcellular level. Microplastic uptake into the gillsand digestive gland was analyzed by a new method using polarized lightmicroscopy. Mussel health status was investigated incorporating histologicalassessment and cytochemical biomarkers of toxic effects and early warning. Inaddition to being drawn into the gills, HDPE particles were taken up into thestomach and transported into the digestive gland where they accumulated in thelysosomal system after 3 h of exposure. Our results show notable histologicalchanges upon uptake and a strong inflammatory response demonstrated by theformation of granulocytomas after 6 h and lysosomal membrane destabilization,which significantly increased with longer exposure times. We provide proof of principle that microplastics are taken up into cellsand cause significant effects on the tissue and cellular level, which can be assessed with standard cytochemical biomarkers andpolarized light microscopy for microplastic tracking in tissue.