Scientists are warning that levels of microplastics in the brain are increasing rapidly. Recent studies suggest that microplastics in the brain have risen by around 50% in less than a decade, mirroring the steep growth in global plastic pollution. Researchers are now trying to understand what this means for human health, especially for the nervous system, which is particularly sensitive to toxic exposures.
Microplastics are tiny fragments of plastic, usually smaller than 5 millimetres, while nanoplastics are even smaller particles that can penetrate cells. These particles come from everyday products such as packaging, textiles and disposable items that break down in the environment. Studies have shown that microplastics are present in drinking water, food and even the air, and that they can enter the bloodstream and circulate throughout the body.
A recent study published in Nature Medicine examined brain tissue from people who died in 2016 and 2024. The researchers found that plastic particles accumulated at significantly higher levels in brain tissue compared with the liver and kidneys, and that concentrations in the brain were about 50% higher in the 2024 samples than in those from 2016. Most of the fragments were made of polyethylene, one of the most common plastics used in packaging. The authors also reported higher levels of microplastics in the brains of people who had lived with dementia, although the study did not prove that the particles caused the disease.
In Sweden, ecotoxicologist Bethanie Carney Almroth from the University of Gothenburg points out that the problem is not only the particles themselves but also the chemicals used to make them. According to research she cites, around 4,000 of the 6,000 plastic-related chemicals that have been studied are classified as hazardous to health, while another 10,000 substances remain poorly characterised. She stresses that new data on plastic pollution are emerging all the time and that the health implications are only beginning to be mapped.
Microplastics and nanoplastics have now been detected in many parts of the human body, including the lungs, liver, kidneys and placenta. Reports from Swedish public broadcaster SVT describe plastic particles in the placenta, blood vessels, bone marrow and even joints such as the knee and elbow. These findings suggest that plastic fragments can cross important biological barriers and lodge in tissues that were once considered well protected. For clinicians, this raises questions about long-term inflammation and subtle tissue damage that may not yet be visible in routine diagnostics.
Much of the evidence on health effects still comes from animal experiments and cell studies. These indicate that exposure to microplastics can contribute to reproductive disorders, lower birth weight, increased cancer risk and behavioural changes in various species. For humans, the state of knowledge is more limited, but researchers expect a clearer picture as more studies link exposure data with clinical outcomes. For now, many experts argue that brain microplastic contamination should be viewed as a potential risk factor that adds to other environmental and lifestyle pressures on health.
At the political level, United Nations member states are negotiating a global plastics treaty aimed at reducing plastic pollution along the entire life cycle of plastics. Some countries and industry representatives argue that the evidence on how microplastics affect human health is still incomplete and that strict measures may be premature. Others counter that the rapid rise in plastic contamination in organs, including the brain, justifies precautionary regulation while research continues.
For many researchers, the most striking aspect of the recent findings is the sheer amount of plastic now detected in such a sensitive organ. Matthew Campen from the University of New Mexico, whose team helped document the rise in brain microplastics, has described the levels as far higher than he had imagined. The discovery that plastic particles can accumulate in brain tissue more than in other organs has shifted the debate from an abstract environmental issue to a very personal question of what is happening inside the human body.
