Feb. 4, 2025 – Microplastics have been found in the brain, showing they can cross the blood-brain barrier, and the amounts of the tiny plastic bits inside our bodies appear to be increasing at a rate that reflects the increasing amount of global plastic waste.
That’s according to a new study led by researchers at the University of New Mexico who measured microplastics in the brains, livers, and kidneys of people who died in either 2016 or in 2024.
Plastic concentrations found in the brain were higher than those found in the kidney or liver, the results showed.
The study was small – fewer than 30 people were represented in each comparison group – but is notable for comparing microplastic amounts in different organs and in people who died about eight years apart. The levels of microplastics found in the brains of people who died in 2024 were about 50% higher than the levels found in the brains of people who died in 2016.
“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,” study author Matthew Campen, PhD, a toxicology expert and professor in the University of New Mexico College of Pharmacy, said in a news release.
Much of previous microplastic research involving actual human beings has focused on finding microplastics by location in the body and also determining the type of plastic. Microplastics have been found in many organs, including the placenta, and in blood, breast milk, saliva, and even plaques that build up in people’s arteries.
One study published last year linked the presence of microplastics and even smaller nanoplastics in plaque buildup inside the carotid artery – which carries blood from the heart to the brain and head – to a higher risk of a heart attack, stroke, or death from any cause.
Laboratory and animal studies suggest the substances have potential health hazards, but so far, scientists have struggled to pinpoint connections with such things as level of accumulation, type of microplastic, or timespan of exposure.
For this latest study, the tissue samples came from the university’s medical investigator, who had done autopsies on the 28 people who died in 2016 and the 24 people who died in 2024. The average age of people who died in 2016 was 45 years old, and the average age of people who died in 2024 was 51, although a statistical analysis suggests age wasn’t related to microplastic levels.
The causes of death were as follows:
- Of the 28 people who died in 2016, nine died of violence or trauma, 12 died of substance use, and seven died of natural causes.
- Of the 24 people who died in 2024, nine died of violence or trauma, two died of substance use, and 13 died of natural causes.
In another analysis, the researchers looked at the brains of another group of people from New Mexico who died from 2019 to 2024 and had been diagnosed with dementia. Their brain tissue had higher levels of microplastics than the people who did not have dementia. The researchers cautioned that their study gave no evidence that microplastics cause dementia. The plastic concentration levels may simply be related to the disease process of dementia.
“We start thinking that maybe these plastics obstruct blood flow in capillaries,” Campen said. “There’s the potential that these nanomaterials interfere with the connections between axons in the brain. They could also be a seed for aggregation of proteins involved in dementia. We just don’t know.”
