Discovery and analysis of microplastics in human bone marrow

The health implications of human exposure to microplastics (MPs) have raised significant concerns. While evidence indicates MPs can accumulate in closed human organs like the heart, placenta, and blood, there is no available data on MP exposure specifically within the human bone marrow. To fill the research gap, this study detected the concentration of microplastics (MPs) in bone marrow samples by pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) and assessed the size range and morphological characteristics of MPs by Laser Direct Infrared Spectroscopy (LD-IR) and scanning electron microscopy (SEM). Our study shows that MPs were present in all 16 bone marrow samples, with an average concentration of 51.29 µg/g ranging from 15.37 µg/g to 92.05 µg/g. Five polymer types-polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), polyadiohexylenediamine 66 (PA66), and polypropylene (PP), were identified. PE was the most frequent polymer detected in the bone marrow, with an average concentration of 30.02 µg/g ranging from 14.77 µg/g to 52.57 µg/g, with a detection rate of 93.75 %. PS had the highest detection rate at 100 % of bone marrow samples, while PVC and PA66 were found in 75 % of samples each. LD-IR analysis revealed the identification of 25 polymer types, with an average abundance of 19.72 particles/g. Of these, 89.82 % of the MPs were smaller than 100 µm. In summary, this study has, for the first time, demonstrated the presence of MPs are deeply embedded within human bone marrow, providing a basis for future investigations into their potential toxicological effects and underlying mechanisms affecting the hematopoietic system.