US study raises “alarm” over rising microplastic concentration in the human brain

US researchers have detected increasing concentrations of microplastics in human brain tissue. Their findings confirmed an increase in microplastic accumulation over time, with PE — the most common plastic used in packaging, bottles, and containers — as the most frequently detected polymer.

Led by toxicologist Matthew Campen, PhD, professor at the University of New Mexico (UNM) College of Pharmacy, the study published in Nature Medicine found that plastic concentrations in the brain were higher than in other organs, such as the liver and kidneys.

Campen says the findings should “trigger alarm” of a “global threat” of microplastic to human health as the study has shown that these particles appear to be higher in dementia samples.

Packaging Insights dives into an online press conference held by UNM, where Campen shares further insights about his research.

“We identified and quantified plastics in the human brain, liver, and kidney and showed that over the past 20 years, the concentration [of microplastic]  in the liver and in the brain has been increasing. The shape of these plastics is like flakes or shards.”

Dementia and microplastic

The research team analyzed brain samples collected from autopsies donated by the New Mexico Office of the Medical Investigator, comparing tissue from 2016 with samples from 2024.

The study found that individuals diagnosed with dementia had up to ten times more plastic in their brains compared to those without the condition. While there is a clear correlation, Campen emphasizes that the study does not prove causation.

He says that the research result does currently not suggest that microplastics are a cause of dementia — rather, their presence is likely elevated as a result of the disease.

The team used transmission electron microscopy to visually examine the same tissue samples that had high polymer concentrations.“This really changes the landscape. It makes it so much more personal. I never would have imagined it was this high. I certainly don’t feel comfortable with this much plastic in my brain, and I don’t need to wait around 30 more years to find out what happens if the concentrations quadruple.”

Dose makes the poison

Microplastics have a tendency to accumulate in fat cells in the brain’s insulating myelin sheath, which surrounds neurons and helps regulate signal transmission.

“We start thinking that maybe these plastics obstruct blood flow in capillaries. There’s the potential that these nanomaterials interfere with the connections between axons in the brain. They could also be a seed for the aggregation of proteins involved in dementia. We just don’t know,” Campen shares.

The findings contribute to growing concerns about rising environmental plastic pollution and its potential impact on human health. Campen warns that even if plastic production ceased today, existing plastics would continue to degrade into microscopic particles in the years to come.

He acknowledges the challenge of encouraging consumers to shift away from plastic packaging and products, as many often shrug when confronted with warnings about environmental contaminants, which are often measured in parts per billion.

“Dose makes the poison. You know there’s been a lot of press about a publication in tea bags lately. If you look at the trends of increasing plastics in our world, they double about every ten to 15 years. I have yet to encounter a single human being who says, ‘There’s a bunch of plastic in my brain and I’m totally cool with that,’” says Campen.