University of New Mexico researchers study where microplastics travel within a body

Marcus Garcia is a postdoctoral fellow at the University of New Mexico’s Health Sciences Center. He is one of the UNM researchers at the cutting edge of research on microplastics and their presence in the human body.

Microplastics are plastic debris less than five millimeters in length, according to the National Oceanic and Atmospheric Administration. Research into microplastics began with research on the effects of plastic pollution on marine life, Garcia said.

UNM made international headlines in February for research that found alarming levels of plastic in human placentas. The researchers’ latest publication studied mice and found that microplastics could travel from their digestive tracts, likely through the bloodstream, and are deposited in organs like the liver, kidney and brain.

The Journal interviewed Garcia about the new research. This interview has been edited for length and clarity.

Q: Can you give us an overview of what this new research tells us?

A: I wish this research had been published a little bit before our placenta paper did. It was our initial findings to show how microplastics translocate, or go specifically from the GI tract into other tissues.

It was a mouse model. We actually did the equivalent dose of what we see humans consume on a weekly basis. We expose these mice for a four-week period to these microplastics, not only one specific type of microplastic, but multiple, just to give more of a realistic, like, what we’re going to see in our environment.

After that four-week period, we isolated some of these tissues, as well as looked into the blood just to see: Are we able to identify these plastics? It’s kind of the same technique that we used for the placental analysis. We did a potassium hydroxide digestion of those tissues as well as the ultracentrifugation to isolate the microplastics themselves.

We were able to identify these microplastics transferring not only into the kidney and liver, but we were able to identify them in the brain. ... It looks like we’re one of the first groups to be able to identify it in the brain. ... The Leslie (microplastics scientist Heather Leslie) group out of Amsterdam had shown in previous work that it was in the blood, so that tells a story that it enters into our circulation, and then can travel into all these different tissues as well.

Q: Do we know what the health concerns are of having microplastics in the liver and the kidney?

In terms of health impacts, we’re still in the early stages of being able to identify those.

But what this study did show was even just in a very acute exposure — so, four-week period, we are seeing different types of metabolic changes — specifically with enzyme metabolism, fat metabolism, hormone metabolism (metabolic processes convert food into energy). These were in healthy mice models.

Q: So we can see there are relationships here between microplastics and metabolic issues?

A: Correct. ... We don’t know how extensive that is. One of the things in our field of work that we always have to consider is: The dose is the poison. So continuing to work to identify, at what dose are we really seeing these bigger changes? And how those changes within metabolism and overall chronic diseases are associated with each other.

Q: What do you most want people to understand about this research?

Microplastics is still a very, very new area. It is very important to understand what is going into our bodies. We want to let people know that it has gone beyond just from our water bottles or things like that, where we’re getting these exposures. It’s so ubiquitous in our environment that we’re getting (microplastic) from our food. We’re getting it from our regular water sources.

Q: What kind of chronic conditions in humans does this research point us to study for potential connection to microplastics?

A: We’re still at the very beginning stages, but just some of the initial studies that we’ve seen are looking at overall GI issues. There’s been some of the previous work that our group has done to show some of those instances of inflammation — so, specifically looking at irritable bowel disease or things along those lines.

Now seeing the accumulation within these other tissues, being able to answer: Is there a potential link between Alzheimer’s, dementia? Especially since we are seeing them in the brain.

Metabolic syndromes. ... We’re seeing a lot more higher incidences of hormonal changes both within male and female, so, how microplastics may be playing a role within that.

We still haven’t investigated accumulation within different fats, so, potentially seeing how that plays a role.

There was that New England Journal of Medicine paper that came out that is showing accumulation of microplastics within the carotid arteries as well. So, looking at potential cardiovascular events that are associated with that as well.