A team of University of New Mexico scientists found that the human brain is the organ with the highest concentration of microplastics and nanoplastics compared to the liver or kidney.
The study, led by Matthew Campen, looked at the brains of people in New Mexico who died in 2016 and 2024. It also included samples from people who died from 1997- 2013 on the east coast.
The total mass concentration of plastics in the analyzed brains increased by about 50% in the 2024 sample compared to the 2016 sample, according to the study.
Microplastic and nanoplastic — or MNP — concentrations in normal brain samples were 7 to 30 times greater than the concentrations seen in livers or kidneys, according to the study.
The researchers used potassium hydroxide to dissolve the brain tissue, which created a slurry — a semiliquid mixture. They then spun the slurry through a centrifuge, and small pellets of plastic collected at the bottom of a tube, according to the UNM Health Sciences Center. The resultant average pellet mass derived from 500 mg of brain tissue was approximately between 3 mg and 41 mg, according to the study.
While there is a positive correlation between dementia and the level of microplastics present, no causal relationship was identified that proved microplastics can cause dementia. The levels of microplastics in the brain tissue of dementia patients may be elevated because of how the progression of the disease breaks down the blood-brain barrier, according to Marcus Garcia, one of the lead researchers.
There are concerns that the increased presence of microplastics in the brain could affect the firing of neurons, according to UNM researcher Eliane El Hayek.
Microplastics that are currently found in our bodies are not from the plastic we’re using today, but from the plastic that was around up to 50 years ago, according to Garcia. This project sounds the alarm about the amount of plastic in the environment, Hayek said.
“The most important finding is that we’ve detected more plastic in human bodies over time,” Hayek said. “They are there and they are increasing. If there is no action to mitigate this exposure, this trend can continue, and that is why we are concerned.”
For now, the team hypothesizes that a primary entryway for MNPs into our bodies is the food that we eat.
Although the brain absorbs a lot of nutrients, it doesn't have a strong filtration system to remove the nanoparticles in the same way the liver and kidney do, Garcia said, and this is why microplastics have accumulated in the brain so easily.
“The degradation of single-use plastic over decades leads to microplastics and nanoplastics ending up in our groundwater and soil,” Garcia said. “This, in turn, ends up in our vegetation as well as what’s being consumed in our livestock. MNPs then accumulate in their tissue, which is what we end up consuming.”
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MNPs can be ingested or inhaled, according to Nature Magazine. Plastic particles are also “intentionally added” to cosmetic products — such as lipstick, lip gloss and eye makeup — to improve their look and feel during application, according to Science News. They often contain additives to enhance their mechanical properties, flexibility, durability, stability and color, which can leech into seawater or the environment when broken down, according to the National Institutes of Health.
Some team members are involved in research projects that investigate further questions raised by the findings, such as how the microplastics are getting into our system and what types of food sources are most susceptible to microplastic accumulation.
“We have ongoing research that investigates the accumulation of polymer plastics in different types of food,” Hayek said. “Different types of meats, cheese, vegetables and processed foods.“
Hayek said she felt a sense of responsibility when conducting this study.
“It’s not like in the past, where the research is only going to be advertised in a small scientific community,” Hayek said. “It is going out to a very large scientific community as well as to the general public.”
Shin Thant Hlaing is a beat reporter for the Daily Lobo. She can be reached at news@dailylobo.com or on X @dailylobo
