How these particles manage to cross the blood-brain barrier has now been shown for the first time in a research study at MedUni Vienna. The study was carried out in animals using oral administrations of micro- and nanoplastic particles made of polystyrene, a widely used plastic, for example in food packaging. The research team led by Lukas Kenner found that tiny polystyrene particles could be detected in the brain as early as two hours after ingestion. With the help of computer models, the researchers now discovered that a certain surface structure (biomolecular corona) is decisive for the passage of the plastic particles into the brain.

Possible negative effects

The blood-brain barrier is an important cellular barrier that protects the brain from the penetration of pathogens or toxins. Intensive research is being conducted on the health effects of plastic particles in the body. For example, MNP in the gastrointestinal tract have already been linked to local inflammatory and immune reactions as well as to the development of cancer. "In the brain, plastic particles could increase the risk of inflammation, neurological disorders or even neurodegenerative diseases such as Alzheimer's or Parkinson's," Kenner explained. But more research is needed, he said.

Nanoplastics are defined as having a size of less than 0.001 millimetres, while microplastics, at 0.001 to 5.0 millimetres, are still partly visible to the naked eye. MNP enter the food chain from packaging waste, among other things. Not only solid but also liquid food plays a role: according to a study, anyone who drinks the recommended 1.5 to two litres of water per day from plastic bottles ingests around 90,000 plastic particles per year in this way alone. However, if you drink tap water, depending on your geographical location, you can reduce the amount you ingest to 40,000, MedUni explained.