New Delhi: A new research published earlier this month confirmed the presence of microplastics in the human brain, adding to a growing body of evidence that the tiny parts of degraded polymers enter the human body through food, water and air and lodge themselves in vital organs.
The study conducted by US researchers, titled ‘Bioaccumulation of Microplastics in Decedent Human Brains’ and published in the journal Nature Medicine on 3 February, said microplastics at much higher concentrations than in other organs such as the liver and kidneys and higher than previous reports for placentas and testes.
More alarmingly, the research found that plastic accumulation appears to be growing over time, having increased by 50 percent over just the past eight years.
In addition, the scientists associated with the University of New Mexico Health Sciences observed that much of the plastic appears to be much smaller than previously appreciated—in the nanometer scale, just about two to three times the size of viruses.
The same research project also showed that people who had been diagnosed with dementia had up to 10 times as much plastic in their brains as everyone else.
The findings are extremely worrying, experts said.
“Concern for microplastics reaching human tissues is growing at an alarming rate due to their environmental and health-related impacts,” said neurologist Dr Yatin Sagvekar, who is associated with Kokilaben Dhirubhai Ambani Hospital in Navi Mumbai.
“These particles are incredibly damaging to our neurological health which is why the recent findings establishing that microplastics get deposited in the brain is concerning,” Savgekar told ThePrint.
Microplastics are synthetic or semi-synthetic, solid, water-insoluble, high-polymer particles under 5mm in diameter. These are formed by the degradation of any plastic product. Plastic particles of a diameter below 1mm are called nanoplastics.
With the large presence of plastics in daily life, human exposure to microplastics, nanoplastics, and associated toxic chemicals has also grown manifold.
Also Read: Coming soon: Norms on monitoring microplastics & limiting exposure through bottled water, food items
Novel research method, concerning findings
The latest research was carried out using a novel method devised by researchers at the same university to specify and quantify the microplastics in human tissues, which was earlier used to document quantities of plastics in human placentas and both human and canine testes.
In the new study, the researchers analyzed brain tissue samples donated by the New Mexico Office of the Medical Investigator, which under Mexican law needs to retain tissues from autopsies for seven years before disposing of them.
The oldest brain tissues dated back to 2016 and were compared with tissues from 2024. All of the samples were collected from the frontal cortex, the brain region above and behind the eyes.
As part of the study, the researchers chemically dissolved the tissue, creating a kind of slurry, then ran it through a centrifuge, which spun out a small pellet containing undissolved plastic.
The pellet was then heated to 600 degrees Celsius, in a process known as pyrolysis and the scientists captured gas emissions as the plastics burned.
This process helped researchers detect and identify more than 10 types of polymers, the most common of which was polyethene, widely used for packaging and to make containers, including bottles and cups.
Additionally, the scientific team also used transmission electron microscopy to visually examine the same tissue samples that had high polymer concentrations. It found clusters of sharp plastic shards measuring 200 nanometers or less—barely bigger than viruses.
The authors noted that these particles are tiny enough to cross the blood-brain barrier, although the exact pathways on how the particles are actually being transported into the brain has yet to be understood fully.
“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 tissues, particularly in the brain,” the researchers noted.
Chief organ under maximum threat
Dr Rajas Deshpande, director of neurology with Jupiter Hospital in Pune explained that because of the hazardous nature of microplastics and nanoplastics, they are likely to harm neurons and disrupt neurological functions.
“This has the potential to generate neurotoxicity, which can serve as the basis for brain problems.” Relatively little attempt is being made to investigate this thoroughly though, he said.
Neurotoxicity happens when the nervous system is damaged due to exposure to toxic substances.
“Also, since these particles take 25-500 years to break down, a much longer stay in the brain may result in acute, sub-chronic, or chronic brain problems due to increased release of neuroinflammatory chemicals and disruption of transporter and receptor function,” Deshpande said.
Experts also pointed out that they are capable of triggering oxidative stress, a state in which free radicals (highly reactive, unstable oxygen molecules) surpass the available amount of antioxidants in the body.
Some potential damage of oxidative stress to the brain includes, but is not limited to, cellular death, and other neurodegenerative ailments like Alzheimer’s and Parkinson’s.
In addition to that, microplastics may serve as vectors for highly toxic chemicals such as phthalates and bisphenols used during manufacturing or even some hazardous metals.
“In the long run these can affect our cognitive ability and can lead to systemic toxicity,” Savgekar underlined.
The developing brain’s vulnerability to the harmful effects of microplastics is frightening, he stressed, as animal models have shown that microplastics when incorporated into the brain can trigger severe “brain-damaging” effects, especially when it is at the sensitive stages of development.
Adults, on the other hand, are likely to suffer from memory loss, low cognitive functioning, and much worse. Adults are also more likely to have different types of microplastic-associated diseases because of chronic exposure to microplastics.
Experts said that, despite research having just skimmed the surface of the presence and ill effects of microplastics in the brain, there’s a critical imperative to deal with what is known by now.
“With the direct ability to cause oxidative stress, inflammation, and neurotoxicity, it’s imperative that microplastic pollution be dealt with through policy change and environmental reforms,” Savgekar said.
It may be also important to adopt measures to mitigate unwanted exposure while understanding the implications of growing plastic dependency, all while protecting human neurology, he added.
(Edited by Sanya Mathur)