A new study has found a dramatic increase in levels of microplastics and nanoplastics (MNPs) in human brains in recent years.
MNPs have previously been detected in human lungs, intestine, bone marrow and placenta.
In the new study, researchers took one tissue sample from the brain, kidney and liver of 80 people autopsied in 2016 and 2024. They also sampled the brains of 12 people who died with Alzheimer’s or dementia within that period.
The researchers found that brain and liver samples from 2024 had considerably higher MNP concentrations compared with those in 2016. Brain samples showed a 50% increase during the eight years.
“Plastic production has been going up, plastic pollution has been going up. It’s perfectly logical that levels of plastic in the human body should be going up at the same time,” Dr. Philip Landrigan, a pediatrician and epidemiologist at Boston College, U.S., not involved with the study, said in a phone call with Mongabay.
“The plastics we’ve thrown away from the ‘70s, ‘80s and ‘90s are now forming into these nanoplastics that are getting into our water, our agricultural system and ultimately our food,” said Matthew Campen, a study co-author and professor in the College of Pharmacy at the University of New Mexico.
Since food packaging is a well-known source of microplastic, researchers expected to find the highest MNP concentrations in the liver, part of the digestive system. However, brain samples had 7-30 times more MNP than liver or kidney samples.
Campen said they expected the brain would be protected by the blood-brain barrier, a membrane that prevents harmful substances in the blood from passing into the brain. “That didn’t seem to be the case,” he said.
Campen hypothesized that plastics were likely “hijacking” their way in with lipids, or fatty molecules that can cross the barrier.
“If you’ve ever cleaned a Tupperware bowl that had butter in it, you know it’s going to take a lot of hot water [to clean]. Plastics love fats; plasticizers are also very lipophilic so they like to move with fats too. So, we think part of why they stay in the brain is the brain has a higher lipid content than other organs,” Campen said.
Brains of people with dementia had up to 10 times more MNPs than other brains but that doesn’t mean MNPs had caused dementia. The elevated rate was likely a result of damage to the blood-brain barrier from the neurodegenerative disease, the authors said.
The study didn’t find more plastic in the brains of older people with more lifetime exposure, suggesting the brain can clear itself of MNPs, Campen said.
Previous studies have found microplastics associated with certain cancers, cardiovascular disease and harm to human reproductive, digestive and respiratory health.
“There’s always need for more studies, but we should not wait on findings from more studies to take action,” Landrigan said.
Banner image of microplastics by 5Gyres, courtesy of Oregon State University (CC BY-SA 2.0).
This story first appeared on Mongabay
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