Microplastics spread from the gut to the brain, other organs
Microplastics have become highly prominent in the environment, including in soil, food, and water.
The authors of the present study define microplastics as plastic particles smaller than 5 millimeters. They wanted to find out how different types of microplastics influenced body organs in mice.
The study authors attempted to replicate consumption of microplastics in a quantity that is similar to human exposure. Mice were exposed to different amounts of polystyrene or mixed polymer microspheres through oral gastric feeding.
After mice were fed microplastics, the researchers examined serum, brain, liver, kidney, and colon tissues to identify the presence of microplastics.
Researchers identified microplastics in multiple organs including the brain, liver, and kidneys of exposed mice. These findings show how microplastics are capable of spreading to other, distant areas of the body.
After microplastic exposure, they also found that specific metabolic changes occurred in the colon, liver, and brain.
These changes depended on how much exposure the mice received and what type of microplastic they were exposed to.
“By exposing mice to levels of microplastics similar to human ingestion, we discovered that these particles can indeed migrate from the gut into organs such as the liver, kidney, and brain,” Garcia explained.
“Previous research from our group has demonstrated that microplastics can disrupt immune function. This could be a problem when dealing with infections or could possibly worsen conditions like inflammatory bowel diseases. Additionally, our study was performed over a 4-week period, showing significant alterations in metabolism. This brings insight into the long-term accumulation of microplastics in the body, raising concerns about chronic exposure. Furthermore, our study revealed substantial metabolic alterations linked to various metabolic and immune disorders, including changes in amino acid, lipid, and hormone metabolism.”
Dr. Heather Leslie, an independent scientist specializing in analyzing microplastics and additives in humans (and ecosystems) based in Amsterdam, not involved in the study, said an important finding of the study is that “laboratory dosed microplastics near the upper particle size limit for crossing gut epithelial layers are not only absorbed after ingestion, but also deposited in organs.”
“This demonstrates in controlled conditions what happens in the body with ‘wild’ microplastics, my term for those microplastics we encounter in our living environment,” Leslie said.
“That is significant because once in place, common microplastic types can start interfering with the biology, as the metabolomics work in the same study showed for multiple organs.”
More studies on effects of microplastics needed
Despite the implications of these findings, the research does have limitations.
First, the researchers used mice for this study, so future research is needed to see if these findings can apply to humans.
Also, the researchers utilized microplastics that did not contain chemical additives common in microplastics that may make consuming microplastics worse. Future research can consider how these chemicals may affect the impact of microplastics on people.
The study did not investigate clearance rates of microplastics, which may influence their impact. Researchers only evaluated the prefrontal cortex of mice’s brains, and they couldn’t precisely note microsphere location. Thus, it’s possible that microplastics didn’t cross the blood-brain barrier.
Researchers further note that their analysis of microplastics was also limited. Future research can focus on better ways to identify and measure microplastics and plasticizers in tissues.
“Further research is critical to answer many questions on how microplastic accumulation plays a role in human health,” Garcia noted.
“We need to understand their overall impact better and the factors influencing their uptake. Currently, we are exploring how microplastics make their way into the brain. Additionally, we are utilizing newly established techniques to investigate the accumulation of microplastics in the human brain, liver, and kidney tissues. These techniques allow us to isolate microplastics from biological tissues and quantify them using pyrolysis-Gas Chromatography/Mass Spectrometry.”
— Marcus Garcia, PharmD, study author
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