Over the past 50 years, environmental microplastics and nanoplastics (MNPs) have increased substantially. Recent studies have shown that MNP buildup leads to inflammation and raises the risk of cardiovascular disease. Previous research in humans used visual microscopy to demonstrate the presence of MNPs in the lungs, intestines, and placenta. Pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) and visualization techniques are used to evaluate the MNP distribution in liver, kidney, and brain tissues of postmortem human samples.
Researchers collected the samples from autopsies that were conducted between 2016 and 2024, that was approved by the University of New Mexico’s Office of the Medical Investigator. A forensic pathologist selected consistent organ regions for the study analysis. MNP concentrations were quantified by using Py-GC/MS to precisely analyze polymer-based particulates. Polarization wave microscopy and scanning electron microscopy (SEM) were utilized to visualize the presence of MNPs in the tissues.
In 2024, the median MNP concentration in liver and kidney samples showed 433 and 404 µg/g, which was higher than previously reported levels in human placentas and testes. The brain samples showed elevated levels of MNP accumulation, with median concentrations of 3,345 µg/g in 2016 and 4,917 µg/g in 2024.
Scientists discovered polyethylene (PE) as the plastic element in the brain, which constituted 75% of MNP concentrations; it was within liver and brain samples from 2016 to 2024 experienced rising amounts of mono polystyrene with high amounts of polypropylene (PP) and polyvinyl chloride (PVC) and styrene butadiene rubber (SBR). MNP concentrations demonstrated significant increases in dementia brain tissues when compared to non-dementia brain tissues as they support plastic accumulation, a potential factor in neurodegenerative diseases. The permanent presence of MNPs caused significant damage to human health, and patterns demonstrated that plastic pollution exceeds the earlier projections. Plastic debris continues to expand at an accelerated rate and reached a high peak during the recent pandemic.
This highlights the need for immediate action on plastic pollution and the need for additional studies on how MNP accumulation impacts health. Further examination of plastic exposure to human health remains essential because it establishes no links between MNP accumulation and disease development. Medical experts should study the links between plastic exposure and neurodegenerative diseases because dementia patients have substantially higher MNP concentrations.
References: Nihart AJ, Garcia MA, El Hayek E, et al. Bioaccumulation of microplastics in decedent human brains. Nat Med. 2025. doi:10.1038/s41591-024-03453-1
