Microplastics have made it to the brain - what science knows about it

Recent studies have shown that these particles can penetrate the lungs, heart, placenta and even cross the blood-brain barrier into the human brain. However, there is still not enough data on how dangerous this is to health, experts say.

The issue of microplastics has become one of the main topics on the way to the adoption of the world's first agreement to combat plastic pollution, discussions on which are continuing at the UN level.

While the effects of microplastics and even smaller nanoparticles on the human body remain poorly understood, scientists continue to seek answers.

One of the most notable studies was published in the journal Nature Medicine in February this year.

American scientists analysed brain tissue samples from 52 deceased residents of New Mexico (USA) and found that the concentration of microplastics in the brain had increased in recent years. According to the head of the study, toxicologist Matthew Campen, in some cases in the brain was able to isolate up to 10 grams of plastic - about the weight of an unused wax pencil.

However, these findings have raised doubts among other experts. Toxicologist Theodore Henry of Heriot-Watt University in Scotland called for the results to be treated with caution until they are independently verified.

"Today, speculation about the possible health effects of plastic particles far outstrips the actual scientific evidence," he said.

Oliver Jones, a chemistry professor at RMIT University in Australia, added that there is still little data even on the prevalence of microplastics in New Mexico, let alone elsewhere.

The scientists admit: the study participants did not suffer from any serious illnesses before they died, and a causal link between microplastics and any health harms has not yet been established.

Most studies of microplastics are still observational in nature and do not allow conclusions about causality. For example, a paper published in the New England Journal of Medicine last year showed a link between microplastic buildup in blood vessels and an increased risk of cardiovascular disease. Experiments in mice also demonstrated that microplastics can cause rare blood clots in the animals' brains, but it is too early to transfer these findings to humans.

The World Health Organisation concluded in the 2022 review: there is not yet enough evidence to assess the risks of microplastics to human health. However, many experts believe that policy should be ahead of science: measures to limit exposure to plastic should be taken now.

According to the Barcelona-based Institute for Global Health, published on the eve of the new UN talks, "full scientific clarity cannot be expected". The report says action must be taken now - limiting exposure to microplastics, improving risk assessment and protecting vulnerable populations - to prevent the situation from becoming a major crisis.

Global plastic production has doubled in the last 20 years and is expected to triple by 2060.