Human activity has caused environmental microplastics and nanoplastics (MNPs) to increase exponentially over the last 50 years. While previous studies have shown that microplastics can both cause and worsen diseases, these trials were conducted using cell cultures and non-human animals. Recent research conducted by Nihart et al. explores rising MNP accumulation in human organs. This study intended to draw a clear connection between microplastics and their effect on human tissues, as well as how MNPs are distributed throughout the body after being taken up from the environment.
Researchers compared plastic accumulation in the brain, liver, and kidneys of patients collected in 2016 and 2024, respectively. By using pyrolysis gas chromatography–mass spectrometry, they could more accurately visualize nanoparticle distribution in these organs compared to previous methods. Most notably, samples that were collected at a later date (in 2024 as opposed to 2016) showed higher MNP concentrations across all organs studied. These results isolated geographic time as the primary factor for MNP accumulation, and it confirmed that age of death, sex, and ethnicity had no significant impact on the amount of plastic accumulation in internal organs.
Nihert et al.’s research shows a higher accumulation of microplastics in the brain compared to microplastic uptake in other organs.
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The MNP concentrations in the liver and kidney samples were similar in 2024, at 433 μg/g and 404 μg/g, respectively. However, the brains that were studied showed a higher median baseline for MNP uptake, with a median plastic concentration of 3345 μg/g in the 2016 samples. The brain also showed the most dramatic increase in plastic concentration, rising to 4917 μg/g in 2024. The brains of dementia patients had an even higher MNP accumulation, with a median of 26,076 µg/g. Dementia impairs the blood-brain barrier, meaning that the brain can take up more substances circulating in the body and can’t easily eliminate them. Therefore, causality cannot necessarily be determined, and future studies would need to be conducted to determine whether microplastics in the brain can definitively cause dementia or are just a byproduct of the disease.
Based on these findings, the authors recommend that future studies focus on the methods by which MNPs are taken into the brain. Since this particular study only researched brain material from the prefrontal cortex, future studies can include a variety of tissue to obtain a more comprehensive view of plastic distribution throughout the brain.
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