The human brain may contain up to a spoon’s worth of tiny plastic shards—not a spoonful, but the same weight (about seven grams) as a plastic spoon, according to new findings published Monday in the journal Nature Medicine.
Researchers detected these “almost unbelievable” levels of microplastics and nanoplastics in the brains of human cadavers, says study co-author Andrew West, a neuroscientist at Duke University, to Science News’ Laura Sanders. “In fact, I didn’t believe it until I saw all the data.”
Based on their analysis, the amount of microplastics in the human brain appears to be increasing over time: Concentrations rose by roughly 50 percent between 2016 and 2024.
The researchers also found much higher levels of microplastics in brain tissue than in liver and kidney tissue. And microplastic concentrations were also higher in the brains of deceased patients who had been diagnosed with dementia compared to the brains of deceased individuals without dementia.
Importantly, the study finds only a correlation between high levels of microplastics in the brain and dementia—it does not establish a causal relationship. It could be, for instance, that changes resulting from dementia make it easier for microplastics to accumulate in the brain. However, the researchers say their findings are troubling nonetheless.
