Researchers Find Nanoplastics in the Human Brain; Say It Is 30 Times More Compared to the Kidneys and Liver

It is no surprise that human bodies take in countless amounts of microplastics due to our increasing usage of plastic products. However, a study revealed that an autopsy result of a cognitively normal human brain sample in 2024 had more minuscule shards of plastics than samples collected in the last eight years before that, according to CNN Health. The braid samples taken from human cadavers had more than 30 times tiny microscopic plastic shards compared to those found in their kidneys and liver, as revealed by Matthew Campen, the study's co-lead author and professor of pharmaceutical sciences at the University of New Mexico.

"The concentrations we saw in the brain tissue of normal individuals, who had an average age of around 45 or 50 years old, were 4,800 micrograms per gram, or 0.48% by weight," Campen said, per the news outlet. "Compared to autopsy brain samples from 2016, that’s about 50% higher. That would mean that our brains today are 99.5% brain and the rest is plastic." Campen clarified that the current method of measuring the presence of plastic in human bodies might have over, or underestimated the levels and they are working to get a precise estimation shortly. Twelve people who were diagnosed with dementia had three to five times the shard-like plastic fragments in their brains compared to cognitively healthy people.

The plastic fragments were mostly found on the walls of arteries and veins in the brain along with the brain's immune cells. "It’s a little bit alarming but remember that dementia is a disease where the blood-brain barrier and clearance mechanisms are impaired," Campen continued. "We want to be very cautious in interpreting these results as the microplastics are very likely elevated because of dementia and we do not currently suggest that microplastics could cause the disease."

"Finding plastic deposits in the brain does not prove they cause damage," Phoebe Stapleton, an associate professor of pharmacology and toxicology at Rutgers University in Piscataway, who was not involved in the study, said in an email. "It is unclear if, in life, these particles are fluid, entering and leaving the brain, or if they collect in neurological tissues and promote disease. Further research is needed to understand how the particles may be interacting with the cells and if this has a toxicological consequence." Researchers also discovered that the human liver and kidneys have some capacity for filtering and flushing out some plastics from the body. However, whether the brain can do the same or not, is still uncertain.

Dr. Philip Landrigan, who is the director of the Program for Global Public Health and the Common Good and the Global Observatory on Planetary Health at Boston College, revealed how the presence of plastic in human tissues makes sense in recent dates due to people's increasing exposure to plastic materials. Along with the brain, fragments of plastic were also found in the human heart, blood vessels, lungs, tests, gastrointestinal tract, and the placenta. "Diet is the main route of exposure for micro and nanoplastics," Landrigan said, adding that some are also airborne. "If you live near the coast, some of the microplastic particles that are in the ocean get kicked into the air through wave action."

These microplastics are said to be less than 0.2 inch to about 1 nanometer. "Based on our observations, we think the brain is pulling in the very smallest nanostructures, like 100 to 200 nanometers in length. These are roughly the size of two COVID viruses side by side," Campen remarked. Nanoplastics are the most worrisome plastics for human health, experts say, because the minuscule pieces can take up residence inside individual cells. Kimberly Wise White, the vice president of regulatory and scientific affairs in the Natural Resources Defense Council, shared that there is still a lot of gap in the current data that can help experts understand how exposure to microplastics happens.