Plastic micro and nanoparticles are more concentrated in postmortem brain samples from 2024 than those from 2016
A recent Nature Medicine Study assessed the relative distribution of microplastics and nanoplastics (MNPs) in large organ systems of deceased human kidneys, liver and brain.
Quantification of MNP accumulation and health risks
MNPs vary in size from as small as 1 nanometer up to 500 micrometer in diameter. Their environmental concentration has increased exponentially in the last 50 years. However, the extent to which they are harmful or toxic to people is unclear. Recent research has linked MNP to higher inflammation and the risk of future unfavorable cardiovascular events.
MNPs have also seen that they aggravate the disease or toxic results in some research into animal exposure, but the relevance of the concentrations for human exposures is unclear. Research did not fully investigate the fabric distribution and the internal dose MNPs in people. Particles are detected in organs, such as the intestines, lungs and placenta, with the help of visual microscopic spectroscopy methods. However, smaller MNPs are often overlooked, because these methods are usually limited to larger (> 5 µm) particles.
A recent approach, namely pyrolysis gas chromatography mass spectrometry (PY-GC/MS), is less biased in combination with orthogonal methods and is more quantitative and cumulative. Moreover, the data is generated by PY-GC/MS more comparable in laboratories, making the results more robust.
About the study
The current study combined the PY-GC/MS and visualization methods to explore the relative distribution of MNPs into liver, kidney and brain tissues of human bodies that underwent autopsy in 2016 and 2024.
A total of 53 brain samples from 2016 and 2024 were analyzed to quantify MNPs. These estimates were compared with similar analyzes that were performed between 1997 and 2013 to understand the change in the speed of MNP’s accumulation in brain tissues.
For this study, small pieces (3-5 cm3) Postmortem human liver (right central parenchym), kidney (wedge piece of cortex and medulla) and brain samples (frontal cortex) samples were obtained from 2016 and 2024 autopsy and stored in 10% formaline . Brain samples were also obtained from repositories on the east coast of the United States.
Study findings
MNP concentrations turned out to be almost comparable in deceased liver and kidney specimens from the sample of 2024, with the median value of total plastics in 433 and 404 µg/g respectively. In comparison with liver and kidney specimens, the MNPS concentration in brain tissues was higher. PY-GC/MS estimates of MNPs in brain samples from 2016 and 2024 samples were 3345 µg/g and 4917 µg/g respectively. The MNP concentration in liver and brain samples from 2024 was higher compared to the 2016 sample. The results were in line with those of a multiple regression analysis of brain concentrations, taking into account the influence of other demographic variables.
The share of polyethylene (PE) in the brain was higher compared to other polymers. The share was also higher compared to PE in the liver and kidney. In liver and brain samples, between 2016 and 2024, the concentrations of polyvinyl chloride (PVC), PE, polypropylene (PP) and styrene-butadieen rubber (SBR) were raised. Polymers other than PE were not so consistent in the prevalence. This can be powered by limited sampling and variation in prevalence over large distributions.
By comparing these results with those from previous time frames (1997-2013), it was noted that the total MNP concentrations were lower in samples from the east coast of the US. Additional analysis also showed that the total plastic concentrations in dementia monsters were higher than in a normal frontal cortex, although no causality was established. Scanning electron microscopy (SEM) with energy dispersive spectroscopy confirmed that particles observed in kidney, liver and brain samples were mainly composed of carbon.
Particles (<1 µm) were noticed in the brain parenchyma and examination by transmission electrone microscopy (Tem) largely revealed 100 - 200 Nm long shards or flakes. Between 2024 and 2016, the total mass monitoring of plastics in the brain increased by around 50%. Increasing environmental concentrations of MNPs can therefore lead to rising internal maximum concentrations.
Conclusions
The current study noticed an increasing trend of MNP concentrations in the brain and liver. Most MNPs found in tissues seemed to be nanoplastic shards or flakes and consisted of PE. In the future, more complex study designs with the help of larger sample sizes are needed to refine the current analytical techniques and to understand whether MNPs influence neurological disorders and other human diseases.