Q&A with University of New Mexico researchers who found microplastics in human placentas

The University of New Mexico made international headlines in February with a study that found microplastics in human placentas.

UNM researchers used new technology to quantify how much plastic they found in the placentas. The amount was higher than expected. The researchers also found microplastics in every one of the 62 placentas tested. Microplastics seem to have negative impacts on human health, but much research still needs to be done to figure out exactly how microplastics affect the human body.

The research was led by Matthew Campen, regent professor of pharmaceutical studies. Postdoctoral fellow Marcus Garcia performed many of the experiments.

This interview has been edited for length and clarity.

Q: Why do you think this study drew so much attention?

Garcia: I think reproductive health is a huge area of interest. I also think that, in terms of being able to adequately quantify microplastics, this is the first time that we’ve been able to (do) that.

Campen: Instead of just saying we see a couple of particles in the placenta, we’re now saying this is in micrograms per gram. ... When people saw how much, it opened eyes. This is not a trace occurrence of a random particle. There’s a lot of polymer in the placenta.

Q: Is this more polymer than you expected to find when you set out to do the study?

Campen: Yeah. ... We know that polymers are all around us, and we know that we’re exposed to them all the time. But the placenta is such a short-lived organ, it’s only eight months old. ... To see how high it got in some of the tissues, upwards of 600 micrograms per gram, was alarming.

Q: Why are microplastics such a concern for human health?

Garcia: They’re identifying microplastics leaching from the ground, entering into our water source, entering into our plants, and even seen in our livestock as well as food. So to be able to see that that enters into our body as we consume these products, I think that’s where the biggest concern is, because this is something where we don’t necessarily know what is going on in the body and how these microplastics are going to be affecting us.

Campen: I was a microplastics skeptic, because I thought, sure, they get to be these small little grains. We’re surrounded by sand and dirt and minerals, and those get in our body, too. But what we’re seeing now, thanks to this new technology, is that plastics really like to get into the body, and our body doesn’t have an effective means of getting rid of them. ... In the placenta, we saw that of the particles we looked at, 75% of them were polymer. So even though we’re sitting on an entire planet worth of other particles, the plastics seem to get in and stay in.

Q: It takes a while for plastic to degrade, so if you’re seeing those microplastics now, are we looking at potentially more as we have all this plastic that hasn’t degraded yet?

Garcia: Yes. Currently, we’re looking at about a doubling time of plastics every 10 to 15 years. Even if we were to stop plastic production today, it would continue to grow in that period of time.

Q: How do you find these microplastics and what is your process for quantifying them?

Garcia: We call it saponification. Ultimately, taking a piece of tissue and turning it into a kind of soap. We get roughly 500 milligrams of any tissue of interest. ... We take potassium hydroxide, and we let it incubate at 40 degrees Celsius for a three-day period. What that does is it breaks down all the tissue material and only leaves a little bit of minerals, but predominantly all the polymers ... and then we use what we call ultracentrifugation, where we spin these samples at a very high speed ... to where it creates just a pellet at the bottom of our ultracentrifuge tube. ... That’s where we move on to the pyrolysis gas chromatography (a method of chemical analysis).

Q: You mentioned the percentages of what you found. Polyethylene was the biggest. (Polyethylene is used to make plastic bags and bottles. It accounted for 54% of the total plastics found in the placentas.) Do we know anything about what that specific polymer can do to human health?

Campen: We have a colleague at Duke University, Andrew West, who late last year published a finding that anionic nanoplastics — which polyethylene can have that kind of charge on it, can exhibit those properties — but he showed that those nano particles could cause a sort of clumping or aggregation of the proteins that we know are associated with dementia. We’re going to work with him in the coming years to find out: Is this sort of a missing link that explains why there’s advanced dementia over the past 20, 30 years?

Q: What other research would you like to do on this topic?

Garcia: One of the things that we want to help answer based off of a sheep study and looking at the placenta in different time points is, is there an association with agriculture that’s playing a role?

Campen: One other study worth mentioning: ... We’re partnering with the Office of the Medical Investigator. In that study, we’re able to get specimens from autopsies. They do a lot of chemical characterization of those samples, and we’ve been able to partner and get access to the samples so we can do this polymer sampling. We are now able to look at distribution of plastics throughout the human body.

Q: It sounds like that’ll build a bigger dataset for people to use.

Campen: It’s eye-opening ... the amount we see in placentas that are only around for eight or nine months pales compared to what we see in adult humans.

Q: Do you think policy is the route to address this issue?

Campen: It has to be. Our policy so far has been to guilt the individuals on this planet into doing something better, but they don’t really have a good way to do anything better. You recycle, but we don’t have sufficient recycling plants. We really need to invest in both recycling plants, as well as waste energy processing plants so that we can make sure that we get rid of this stuff rather than just letting it build up in landfills.