According to new research, the average American may be walking around with 5 grams of nano-size microplastic trapped in his or her brain. That's about the weight of your average size plastic spoon.

New research indicates that microplastics are infiltrating human brains at levels higher than those found in other vital organs, according to a study published in Nature Medicine on February 3rd. This discovery suggests that tiny plastic fragments are capable of crossing the brain's protective blood-brain barrier, potentially affecting health and cognitive functions.

Researchers at the University of New Mexico (UNM) analyzed autopsy samples from 2016 and 2024. Over this eight-year span, they observed a 50% increase in the concentration of microplastics within the brain. By 2024, the amount of microplastics in some brain samples was equivalent to the weight of a plastic spoon.

Significantly higher concentrations of these plastic particles were found in the brains of individuals who had dementia. Matthew Campen, the lead researcher and toxicologist, expressed surprise and concern over these findings during a recent press conference. He noted, "People are simply being exposed to ever-increasing levels of micro- and nanoplastics," highlighting that these particles are minuscule, roughly the width of two COVID viruses side by side.

The accumulation rate of these plastics mirrors the growing environmental exposure. Over time, as plastic degrades, it breaks down into smaller particles that can enter the human body and brain.

Plastic Pollution in Organs

The study revealed that brain tissue contains 7 to 30 times more microplastics than organs like the liver or kidneys, marking it as one of the most affected tissues. The researchers examined 52 human brain samples from the frontal cortex, which is crucial for judgment, decision-making, and muscle movement, spanning from 2016 to 2024.

The concentration of microplastics in the brain reached approximately 5,000 micrograms per gram, significantly higher than the 400 micrograms per gram found in the liver and kidneys. For comparison, earlier brain samples from the eastern U.S. (1997–2013) showed lower levels, around 1,250 micrograms per gram, indicating a trend of increasing plastic accumulation over time.

To illustrate the volume of microplastics in the brain, Campen used the analogy of a plastic spoon, explaining that with a brain weighing about 1,400 grams, a concentration of 5,000 micrograms per gram translates to over 5 grams of plastic, which is roughly the weight of a plastic spoon.

In individuals who died with dementia, the levels were alarmingly high, exceeding 26,000 micrograms per gram. In these cases, some particles were found clumped together in areas of inflammation, suggesting a potential link between microplastics and brain tissue damage, though the study does not confirm that these plastics directly cause dementia symptoms. Campen also suggested that the disease process might impair the brain's ability to clear out these plastics.

Common Plastics Found in the Brain

The study identified 12 types of plastics in the brain, with polyethylene (PE), commonly found in bottles, bags, and containers, accounting for 75% of the total. Other plastics included those used in packaging, car parts, pipes, computer keyboards, flooring, and various plastic products we come into contact with every day. "It was notable that these are largely mirroring proportions of polymers that we do see in our environment," explained Marcus Garcia, a study co-author and postdoctoral researcher at UNM.

The particles in the brain were primarily sharp nanoscale shards and flakes, small enough to cross the blood-brain barrier. However, the exact mechanism by which these particles enter the brain remains unclear. Researchers speculate that micro- and nanoplastics enter the body through ingestion, inhalation, and possibly through the skin. These particles have been detected in various body parts, including arteries, hearts, lungs, blood, and placentas, with a recent study on January 30th showing higher levels of microplastics in placentas from premature births.

One hypothesis is that organs like the liver and kidneys, designed to filter toxins, might not be as effective at clearing plastics, while the brain's clearance systems are even more limited. Campen likened the situation to cleaning grease from a plastic container, suggesting that brain tissue, which is about 60% fat, might trap these particles more effectively.

This finding also raises concerns about the use of plastics in medical applications like heart stents or artificial joints. Campen believes the physical presence of these particles might be more problematic than any chemical toxicity, potentially obstructing blood flow in capillaries or disrupting connections between brain cells.

The Bigger Picture

Despite the alarming increase in microplastic levels, Campen finds some optimism in the data: similar levels in both older and younger individuals suggest natural bodily processes might help manage or eliminate these plastics over time. He noted that many particles originate from old, degraded plastics discarded into the environment, which could inform future environmental policies.

Transition to healthier, more environmentally sound plastics made from hemp might hold the answer to this national health crisis. But many legal and cultural barriers will first need to be overcome in order to implement widespread change. It seems that industrial hemps undeserved association with recreational cannabis (pot) use has impeded the adoption of safe, biodegradable hemp plastics.

We also need effective policies aimed at reducing plastic pollution. After all, microplastic levels in the environment are doubling every 10 to 15 years. Currently, there are no treatments to remove microplastics from the body, but Campen and his team are exploring sources of these pollutants in the environment so we as a society can take aim at the biggest culprits first.

"I don’t feel comfortable with this much plastic in my brain," Campen admitted, urging action before we see the long-term consequences from rising concentrations of petroleum-based plastics that are weighing heavier on our mind everyday.