The exponential rise in microplastic pollution over the past 50 years may be reflected in increasing contamination in human brains, according to a new study.
The Guardian reports that the study found a rising trend in micro- and nano-plastics in brain tissue found from dozens of postmortems carried out between 1997 and 2024. The researchers also found tiny particles in liver and kidney samples.
The human body is widely contaminated by microplastics. They have also been found in blood, semen, breast milk, placentas and bone marrow. The impact on human health is largely unknown, but they have been linked to stroke and heart attacks.
The scientists also found that the concentration of microplastics was about six times higher in brain samples from people who had dementia. However, the damage dementia causes in the brain would be expected to increase concentrations, meaning no causal link should be assumed.
“Given the exponentially rising environmental presence of micro- and nano-plastics, this data compels a much larger effort to understand whether they have a role in neurological disorders or other human health effects,” said the researchers, who were led by Prof Matthew Campen at the University of New Mexico in the US.
Microplastics are broken down from plastic waste and have polluted the entire planet, from the summit of Mount Everest to the deepest oceans. People consume the tiny particles via food, water and by breathing them in.
Several studies have found tiny plastic pollution to be significantly higher in placements from premature births. An analysis found that microplastics can block blood vessels in the brains of mice, causing neurological damage. But the studies have noted that human capillaries are much larger.
New research published by the Journal of Nature Medicine analyzed samples of brain, liver and kidney tissues from 28 people who died in 2016 and 24 who died in 2024 in New Mexico. Microplastic concentration was much higher in brain tissue. It was also higher in brain and liver samples from 2024, compared to those from 2016.
The scientists extended the analysis with brain tissue samples from people who had died between 1997 and 2013 on the US east coast. The data showed an increasing trend in microplastic contamination of brains from 1997 to 2024.
The most common plastic found was polyethylene, which is used in plastic bags and food and drink packaging. It made up 75% of the total plastic on average. The particles in the brain were mostly nanoscale shards and flakes of plastic. The plastic concentrations in the organs were not influenced by the age of the person at death, or the cause of death, their sex or their ethnicity.
The scientists noted that only one sample from each organ was analyzed, meaning the variability within the organs remains unknown and that some variation in the brain samples could be due to geographic differences between New Mexico and the US East Coast.
“These results highlight a critical need to better understand the routes of exposure, uptake and clearance pathways and potential health consequences of plastics in human issues, particularly in the brain,” said the researchers.
