Tissue-specific microplastic burdens in humans: An intra-individual mapping of 18 tissue types

Microplastics (MPs) are ubiquitous environmental contaminants, yet their tissue-specific distribution within individuals remains poorly characterized. We analyzed 165 samples from 18 tissue types collected from ten donors, including two newborns, using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and Laser Direct Infrared (LDIR) imaging for chemical quantification and morphological characterization, respectively. MPs were detected in all donors and tissues, with substantial inter-individual and tissue-specific variation. MP burdens in the two neonatal donors fell within the range observed across the adult donors. MP accumulation was tissue-specific, with lipid-rich tissues (adipose and brain) and highly perfused endocrine/metabolic organs (adrenal, liver, thyroid) harboring the highest burdens, whereas blood contained the lowest MP levels. Polyethylene (PE), polyamide 66 (PA66), and polyvinyl chloride (PVC) accounted for > 90% of the 11 MP types quantified by Py-GC/MS. LDIR analysis showed that MPs were predominantly small (66.06% within 20-40 μm) and moderately rounded, although particles > 150 μm were also detected across tissues. These findings provide a systematic map of human MP distribution, demonstrating heterogeneous tissue accumulation and providing a understanding for the absorption, distribution, metabolism, and excretion (ADME) of MPs and associated their health risks.