Microplastics Found in Human Brains: What It Means for Health

Plastic features in our clothing, cars, mobile phones, water bottles and food packaging. However, recent research is adding to concerns about the effects that tiny plastic particles may have on human health.

A US study has detected microplastics in human brains for the first time. The research has not yet been independently confirmed by other scientists, but media coverage has described it as scary, shocking and alarming.

So, what are microplastics? What could they mean for our health, and is there reason to worry?

What are microplastics, and can you see them?

We tend to think of plastic products as indestructible, yet plastic eventually fragments into smaller pieces. Definitions differ, although microplastics are generally classed as particles measuring less than five millimetres.

Some are therefore too small to spot with the naked eye. Many images used by the media in articles about microplastics can consequently be misleading, because they depict much bigger pieces that are plainly visible.

Microplastics have been identified in numerous drinking-water sources and commonly consumed foods. As a result, our diets expose us to them continually.

This pervasive, chronic (long-term) exposure presents a potentially serious issue for human health. Research into the possible health risks posed by microplastics remains limited, but the body of evidence is expanding.

What did the latest microplastics study find?

The study examined microplastic concentrations in 51 samples from men and women that had been retained following routine autopsies in Albuquerque, New Mexico. The samples came from the liver, kidneys and brain.

Because these particles are so small, they are challenging to investigate even with powerful microscopes. Rather than attempting to view them directly, researchers are increasingly using sophisticated instruments to establish the chemical composition of microplastics within a sample. This was the method used for the study.

Researchers were surprised to discover up to 30 times more microplastics in brain samples than in samples from the liver and kidneys.

They suggested that this might result from the brain's high blood flow, which could carry plastic particles with it. Another possibility is that the liver and kidneys are better equipped to process external toxins and particles. The brain also experiences less cellular renewal than other organs, which could allow plastics to remain there.

The team further found that plastic levels in brain samples rose by roughly 50% from 2016 to 2024. This could reflect increasing environmental plastic pollution and greater human exposure.

Most microplastics identified in the study were made from polyethylene. This is the world's most widely manufactured plastic and is used in many everyday items, including bottle tops and plastic bags.

Finding microplastics in human brains for the first time is significant. However, the research is a "pre-print", meaning that independent microplastics researchers have not yet reviewed or validated it.

How do microplastics reach the brain?

Microplastics generally enter the body through contaminated water and food. They may disrupt the gut microbiome - the community of microbes living in the gut - and trigger inflammation. This can affect the entire body through the immune system and the complex two-way communication network linking the gut and brain. This gut-brain axis is involved in many aspects of health and disease.

Airborne microplastics can also be inhaled. After particles enter the lungs or gut, they can pass into the bloodstream and circulate to different organs around the body.

Research has identified microplastics in human faeces, joints, livers, reproductive organs, blood, blood vessels and hearts.

They have also been found to travel to the brains of wild fish. Studies in mice show that ingested microplastics can be absorbed from the gut into the blood, enter the brain and become lodged in other organs on their journey.

To enter brain tissue, microplastics need to cross the blood-brain barrier, a complex layer of cells intended to stop substances in the blood from reaching the brain.

While this is concerning, it is not unexpected. Microplastics must pass through similar cellular barriers to reach urine, testes and the placenta, all places where they have already been detected in humans.

Are microplastics in the brain a health concern?

The effects of microplastics in the human brain are not yet known. Some laboratory experiments indicate that they may increase inflammation and cellular damage in the brain, alter gene expression and change brain structure.

Beyond the impact of the particles themselves, microplastics could present risks by transporting environmental toxins or bacteria into and around the body.

Plastic chemicals may also leach from microplastics into the body. These include the well-known hormone-disrupting chemicals called BPAs.

Studying microplastics and their effects is difficult. Alongside their minute size, the environment contains many different types of plastic. More than 13,000 chemicals have been identified in plastic products, and further chemicals are developed every year.

Environmental exposure and digestive processes also weather microplastics, and reproducing this in laboratory conditions is challenging.

One aim of our research is to establish how these factors alter the behaviour of microplastics in the body. We intend to examine whether improving the gut barrier's integrity through diet or probiotics can stop microplastics moving from the gut into the bloodstream. This could effectively prevent particles from circulating through the body and becoming lodged in organs.

How can I reduce my exposure to microplastics?

Microplastics are widespread in the environment, making exposure hard to avoid. We are only beginning to understand the ways in which they might affect health.

Until stronger scientific evidence is available, the most practical approach is to reduce our contact with plastics where possible and create less plastic waste, so that less plastic reaches the environment.

A straightforward starting point is avoiding food and drink packaged in single-use plastic, or reheated in plastic containers. We can also reduce exposure to synthetic fibres in our homes and clothing.

Sarah Hellewell, Senior Research Fellow, The Perron Institute for Neurological and Translational Science, and Research Fellow, Faculty of Health Sciences, Curtin University; Anastazja Gorecki, Teaching & Research Scholar, School of Health Sciences, University of Notre Dame Australia, and Charlotte Sofield, PhD Candidate, studying microplastics and gut/brain health, University of Notre Dame Australia

This article is republished from The Conversation under a Creative Commons licence. Read the original article.