How worried should we be about microplastics in our brains?

Microplastics have been found in human blood, semen, breast milk, placental tissue and bone marrow, but their presence in the human brain is particularly "troubling", wrote Ben Spencer, science editor of The Times.

A recent University of New Mexico study, published in the journal Nature Medicine, found that levels of microplastics in brain-tissue samples from people who had died in 2024 were 50% higher than in similar samples from people who had died in 2016 – and the brain samples contained up to 30 times more microplastics than samples from the kidneys and liver.

What are microplastics?

Microplastics are tiny shards, fragments and flakes of plastic that measure less than 5mm in length. They can be created as larger plastic debris disintegrates and they also exist as microbeads in health and beauty products, such as toothpaste, and skin cleansers and exfoliators. Microplastics pass easily through water-filtration systems, so end up in oceans and rivers, lakes and seas, and have been found in household water supplies and bottled water.

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Toxicologist Matthew Campen, from the University of New Mexico and a named author on the tissue-sample study, estimates he could "isolate about 10g of plastics from a donated human brain – that's about the weight of an unused crayon", said Nature.

Should we be worried?

Concentrations of microplastics in the human body seem to be increasing year by year, as the University of New Mexico study results confirm.

The researchers also found higher microplastic levels in the brains of people who had had a dementia diagnosis – although, the researchers stressed, the correlation does not necessarily indicate a connection.

The implications are "concerning", Antonis Myridakis, lecturer in environmental sciences at Brunel University of London, told The Times. "But it is too early to draw conclusions about direct health risks."

The study authors said their findings highlight a "critical need to better understand the routes of exposure and uptake of microplastics" and the "potential health consequences" for the human body, "particularly in the brain".

What can we do?

Microplastics are "so small, tough and long-lasting that, when they get embedded in tissue itself, we cannot dislodge them", wrote Spencer in the Times. The key, therefore, is reducing our exposure in the first place, and changing how we drink and eat can make a big difference.

Switching from bottled to filtered tap water could reduce microplastic intake from 90,000 to 4,000 particles a year, Canadian doctors, commenting on the University of New Mexico study, said. Ditching plastic teabags could also help, as well as no longer heating food in plastic containers. "Using glass or stainless-steel" containers instead can avoid releasing "staggering amounts of microplastics – up to 4.22 million per square centimetre – in just three minutes".

And there is some cause for hope, Tamara Galloway, professor of ecotoxicology at Exeter University told The Times. Although microplastic concentrations in our organs are currently increasing, "the reverse to that is, if we were to reduce exposure, we could reduce the concentrations" in our bodies, too.