Want to avoid microplastics in your brain? Here’s how you could

People should avoid bottled water if they want to reduce the volume of microplastics that collect in their brain, scientists have said.

The recommendation comes after a recent study suggested that some human brains may now contain up to 7 grams of plastic — about as much as goes into making a small spoon.

Researchers said they were particularly concerned about particles smaller than 200 nanometres, or less than 1/500 of the width of a human hair. Mostly composed of polyethylene, the world’s most popular plastic, these appeared to gather in the walls of blood vessels in the brain as well as in immune cells. The very small size of some fragments may allow them to cross the blood-brain barrier, the tightly locked layer of cells that defends the brain from germs and other harmful substances.

The new article, in the journal Brain Medicine, said that strategies for reducing exposure included switching from bottled to filtered tap water alone. This could reduce microplastic intake from 90,000 to 4,000 particles a year, it said.

“Bottled water alone can expose people to nearly as many microplastic particles annually as all ingested and inhaled sources combined,” said Brandon Luu of the University of Toronto.

“Switching to tap water could reduce this exposure by almost 90 per cent, making it one of the simplest ways to cut down on microplastic intake.”

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Other significant sources include plastic teabags, which can release millions of micro and nano-sized particles. He also highlighted the heating and storing of food.

“Heating food in plastic containers — especially in the microwave — can release substantial amounts of microplastics and nanoplastics,” he said. “Avoiding plastic food storage and using glass or stainless steel alternatives is a small but meaningful step in limiting exposure.”

The earlier study, published in Nature Medicine, involved tissue samples taken from 52 people who died in 2016 and 2024. The scientists were able to detect microplastics as small as 1/100,000 of the width of human hair.

The accumulation in the brain samples of people who died in 2024 were about 50 per cent higher than in those who died in 2016, suggesting the concentration in our bodies is rising as the environment becomes more polluted.

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Levels were also found to be higher in individuals with documented dementia diagnoses, though the researchers emphasised that they had not shown that plastics harmed brain health. Instead, they had merely found hints of a correlation. The study also found that brain tissues showed 7-30 times higher concentrations of plastics compared with other organs such as the liver and kidney.

Experts said that the findings were concerning, but that it was too early to draw conclusions about direct health risks. Humans have always breathed and ingested particles such as pollen and volcanic ash, and our bodies have mechanisms, including hairs and mucus in our airways, designed to catch and remove them.