Post-mortem evidence of microplastic bioaccumulation in human organs: insights from advanced imaging and spectroscopic analysis

Humans are chronically exposed to airborne particulate matter and environmental microplastics through food, water, and consumer products. These anthropogenic pollutants may accumulate in human tissues, but their distribution and chemical identity remain poorly understood. In this study, we analyzed samples of human brain, liver, thyroid, kidney, heart, skeletal muscle, and lung tissue collected post-mortem to assess the presence and composition of micro- and nanoplastics (MNPs). Tissue samples were digested using hydrogen peroxide (30% H₂O₂) and processed via alumina filtration. The retained residues and filtrates were characterized using optical microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), dynamic light scattering (DLS), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and optical photothermal infrared (O-PTIR) microscopy. Our analysis revealed a wide range of inorganic particles (primarily aluminosilicates and carbonates) and synthetic polymers, including polyethylene terephthalate (PET), polystyrene (PS), polyacrylonitrile (PAN), and cellulose derivatives. Notably, PS, PET, and PAN nanoparticles (<0.02 µm) were detected in the filtrates, indicating their potential to cross biological barriers and accumulate at the nanoscale. The thyroid, kidney, and brain tissues showed the highest levels of microplastic contamination, with up to 40.4 MP/g (wet weight) detected. These findings confirm the heterogeneous organ-specific accumulation of environmental polymers and highlight the potential of human autopsy tissues as biomonitors for environmental plastic exposure. The application of advanced spectroscopic techniques enables precise identification of polymeric contaminants and supports further research on their environmental origins and pathways of human exposure.