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A new study conducted in mice found that microplastics can spread from the gut to vital organs in the body, such as the brain. BEN STANSALL/AFP via Getty Images
  • Microplastics are tiny plastic particles that often make their way into many substances, including food.
  • Researchers are interested in understanding how consuming microplastics may influence bodily health and functioning.
  • A new study conducted in mice found that microplastics can spread from the gut to vital organs in the body, such as the brain, liver, and kidneys.

Humans and animals are often exposed to microplastics because they are present in many substances.

As researchers seek to understand the impact of microplastics, evidence is building about the effects of exposure to these substances and how that may influence health outcomes.

A study published April 10 in Environmental Health Perspectives examined how consuming microplastics in amounts similar to those found in our environment affected mice.

According to the study authors, ingested microplastics spread from the gut to the brain, liver, and kidneys.

“Our findings suggest that microplastic exposure can lead to metabolic changes in these tissues, indicating potential systemic effects,” study author Marcus Garcia, PharmD, a postdoctoral fellow at the University of New Mexico College of Pharmacy, told Medical News Today.

“The implications of our findings for human health are substantial.”

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.”

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

This study adds to existing literature about the scope and influence of microplastics, but more work needs to be done to fully understand the effects.

In the meantime, there are a few ways to reduce your risk of exposure to these substances.

For instance, recent evidence suggests that boiling water and pouring it through a coffee filter may help eliminate many of the microplastics found in water. If research continues to confirm these findings, this could become a more common practice.

Leslie proposed additional suggestions for reducing your risk of microplastics exposure:

  • choose plastic-free clothing and other goods
  • opt for whole, minimally processed foods
  • drinking filtered water

“At this point I think we’re in need of a clear intention to take responsibility for ourselves, and act in accordance with our individual unwillingness to be polluted by microplastics. This translates into decisions we make when we’re buying anything that’s shedding plastic particles on us that we do not need or want,” Leslie said.

“It’s about taking small steps to design these things into your life and you’ll start to feel a shift. It’s fun to experiment with saying ‘no’ if it’s something you previously believed you were obliged to own,” Leslie added.

Non-study author Tracey Woodruff, PhD, professor and director with Environmental Research and Translation for Health (EaRTH) Center at the University of California, San Francisco, told MNT the current evidence shows that policy makers must act as soon as possible to prevent human exposure to microplastics from increasing further.

“We know that plastic production is expected to grow rapidly in the next decade and that is going to mean more microplastics. Government actions are the most equitable and efficient way to ensure people [do] not get exposed. In the meantime, people can limit their use of plastics, and can switch to glass/ceramic and metal containers for water and storage containers. Also actions like washing hands and wet mop and heap filter vacuums keeps dust exposures down where MPs [microplastics] and other chemicals like to congregate.”

– Tracey Woodruff, PhD, environmental research professor