Increase in Microplastics in Human Brains

A new study suggests the amount of microplastics accumulating in human brains is increasing.

Research published in Nature Medicine found that greater concentrations of tiny plastic particles were detected in postmortem brain samples from 2024 than in those from 2016.

These particles may also accumulate at higher levels in the human brain than in the kidney and liver, according to the paper.

The study, led by Matthew Campen and colleagues from the University of New Mexico, used novel methods to analyse the distribution of micro- and nanoparticles in samples of liver, kidney and brain tissues from human bodies that underwent autopsy in 2016 and 2024.

A total of 52 brain specimens (28 in 2016 and 24 in 2024) were analysed.

The authors found that liver and brain samples from 2024 had significantly higher concentrations of plastic micro- and nanoparticles than those from 2016.

They then compared these findings with those of brain tissue samples from earlier time frames (1997–2013) and note that there were higher concentrations of plastic particles in the more recent tissue samples.

Campen and colleagues also found a higher concentration of micro- and nanoplastic particles in 12 brains from individuals with a documented dementia diagnosis than in those without.

Micro- and nanoparticles were detected in all of the tissue samples, and similar concentrations were found in the samples of liver and kidney tissues obtained in 2016.

However, brain samples taken from that time, all derived from the frontal cortex region, contained substantially higher concentrations of plastic particles than the liver and kidney tissues.

The amount of environmental plastic nano- and microparticles, which range in size from as small as 1 nanometer (one billionth of a meter) up to 500 micrometers (one millionth of a meter) in diameter, has increased exponentially over the past 50 years.

However, whether they are harmful or toxic to humans is unclear.

The authors note that the findings identify an association but do not establish a causal link between plastic particles and health effects.

Likewise, they suggest that some variation in the brain samples could be due to geographic differences, as samples were retrieved from New Mexico and locations on the US east coast.

The authors said longer-term studies with larger, more diverse populations are needed to determine micro- and nanoparticle accumulation trends and their potential health implications.

Oliver Jones, Professor of Chemistry at RMIT University, said care should be taken when interpreting the results of the study.

“I can see this paper getting a lot of attention due to its scary-sounding title, but I’d urge caution,” he says.

“Before we get headlines like ‘Our brains are now made of plastics,’ we need to step back and look at how this study was conducted and what that might mean for the results.”

He notes that the authors only tested 52 brain samples in total, and therefore “there is not enough data to make firm conclusions on the occurrence of microplastics in New Mexico, let alone globally”.

He also points out that data from only two years is presented and the main analytical method used (pyrolysis gas chromatography-mass spectrometry) can give false results when used to measure plastics. He says it is challenging to properly account for potential contamination while handling or analysing samples in microplastic studies.

“Overall, the work is interesting, but the low sample numbers and potential analytical issues mean that care should be taken when interpreting the results,” he said.

“While it is not impossible that there are microplastics in the brains of some people, this study does not prove that this occurs, and, as the authors themselves note, there is as yet no strong evidence of any health effects.”