Microplastics accumulating in human brains, study finds

Microplastics found in ocean life off Greece

The long-term effects of microplastics on humans are unknown

(Image credit: Louisa Gouliamaki / AFP via Getty Images)

published 4 February 2025

What happened

Microplastics are amassing in the human brain, with the amount increasing over time, according to a study published Monday in the journal Nature Medicine.

The researchers examined samples of 52 autopsied brains from 2016 and 2024 and found a 50% increase in the tiny plastic particles in those eight years. They also studied liver and kidney samples from the same patients and found only a slight increase in the relatively small amounts of microplastics. Previous studies have found microplastics in the human placenta, blood, testicles and coronary arteries, but the large amounts in the brain were a "surprise because of the blood-brain barrier," USA Today said.

Dr. Matthew Campen, a University of New Mexico toxicology professor and a lead author of the study, said the 7 grams of microplastics found in the 2024 brains was roughly equivalent to a plastic spoon. The levels were three to five times higher in 12 brains from people who had been diagnosed with dementia, but the researchers made "no claims to causation — just correlation," the Los Angeles Times said.

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The long-term effects of microplastics on humans are unknown, but studies of mice brains "found troubling signs," The Washington Post said. "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," Campen said. But "there are no control groups" with microplastics, he added. "Everyone is exposed."

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Peter has worked as a news and culture writer and editor at The Week since the site's launch in 2008. He covers politics, world affairs, religion and cultural currents. His journalism career began as a copy editor at a financial newswire and has included editorial positions at The New York Times Magazine, Facts on File, and Oregon State University.