Bioaccumulation of Microplastics in Decedent Human Brains Assessed by Pyrolysis Gas Chromatography-Mass Spectrometry
May 6,2024 | National Library of Medicine
Rising global concentrations of environmental micro- and nanoplastics (MNPs) drive concerns for human exposure and health outcomes. Applying pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) methods to isolate and quantify MNPs from human samples, we compared MNP accumulation in kidneys, livers, and brains. Autopsy samples from the Office of the Medical Investigator in Albuquerque, NM, collected in 2016 and in 2024, were digested for Py-GC/MS analysis of 12 polymers. Brains exhibited higher concentrations of MNPs than liver or kidney samples. All organs exhibited significant increases from 2016 to 2024. Polyethylene was the predominant polymer; the relative proportion of polyethylene MNPs was greater in brain samples than in liver or kidney. Transmission electron microscopy verified the nanoscale nature of isolated particles, which largely appeared to be aged, shard-like plastics remnants across a wide range of sizes. Results demonstrate that MNPs are selectively accumulated into the human brain and concentrations are rising over time.
The ubiquitous presence of plastics, especially polymer-derived particulates ranging from 500 micrometers in diameter down to 1 nanometer, defined as micro- and nanoplastics (MNP), is a defining feature of the Anthropocene epoch1. The extent to which microplastics cause harm or toxicity is unclear, although recent studies associated MNP presence in carotid atheromas with increased inflammation and risk of future adverse cardiovascular events2,3. In controlled exposure studies, MNPs clearly enhance or drive toxic outcomes4–6. The mantra of the field of toxicology – “dose makes the poison” (Paracelsus) – renders such discoveries as easily anticipated; what is not clearly understood is the internal dose in humans.
To date, several studies have utilized visualization and spectroscopic methods to identify and count particulates in organs such as the lungs, intestine7, and placenta8. These methods are often limited to larger (>1–5μm) particulates, thus nanoplastics are excluded from the quantitation. As a novel approach, pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) has been applied to blood9, placentas10 and recently major blood vessels2,3 in a manner that appears more cumulative and quantitative, and less biased than visual identification methods. Py-GC/MS data between labs has been comparable, providing confidence in this method for human tissue analysis2,9,10. We applied Py-GC/MS to assess the relative distribution of MNPs in major organ systems from human decedent livers, kidneys, and brains.