Summary:
This is a cross-sectional observational study that investigated the presence of microplastics and nanoplastics (MNPs) in human organs such as the brain, liver and kidneys. MNPs are tiny plastic particles ranging in size from less than one nanometre to 500 micrometres. Environmental levels of these particles have increased rapidly over recent decades, but their effects on human health remain uncertain. Previous studies have linked MNPs with increased inflammation and a higher risk of cardiovascular disease. However, little is known about how much plastic accumulates in human tissues. This study analysed post-mortem brain, liver and kidney tissue collected between 2016 and 2024. The brain contained substantially higher concentrations of MNPs than either the liver or kidneys, with levels increasing over time. Polyethylene, the plastic commonly used in products such as plastic bags and food packaging, was the most abundant particle detected. The study also examined brain tissue from people with dementia and found considerably higher concentrations of MNPs than in individuals without dementia. However, the researchers emphasised that these findings do not mean that plastic particles cause dementia, rather they suggest an association that requires further investigation. Overall, this study provides evidence that MNPs are present in human organs, particularly the brain, and that concentrations appear to be increasing over time.
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Abstract:
Rising global concentrations of environmental microplastics and nanoplastics (MNPs) drive concerns for human exposure and health outcomes. Complementary methods for the robust detection of tissue MNPs, including pyrolysis gas chromatography–mass spectrometry, attenuated total reflectance–Fourier transform infrared spectroscopy and electron microscopy with energy-dispersive spectroscopy, confirm the presence of MNPs in human kidney, liver and brain. MNPs in these organs primarily consist of polyethylene, with lesser but significant concentrations of other polymers. Brain tissues harbor higher proportions of polyethylene compared to the composition of the plastics in liver or kidney, and electron microscopy verified the nature of the isolated brain MNPs, which present largely as nanoscale shard-like fragments. Plastic concentrations in these decedent tissues were not influenced by age, sex, race/ethnicity or cause of death; the time of death (2016 versus 2024) was a significant factor, with increasing MNP concentrations over time in both liver and brain samples (P = 0.01). Finally, even greater accumulation of MNPs was observed in a cohort of decedent brains with documented dementia diagnosis, with notable deposition in cerebrovascular walls and immune cells. These results highlight a critical need to better understand the routes of exposure, uptake and clearance pathways and potential health consequences of plastics in human tissues, particularly in the brain.
Article Publication Date: 31/03/2025
DOI: 10.1038/s41591-024-03453-1
