Smaller plastic particles have more effects on neurons, the key information processing cells of the brain, new research from the University of Eastern Finland shows. In the study, neuronal cells were exposed to polystyrene nanoplastics at low doses to study subtle changes.

Plastic production continues to rise, despite worldwide concerns. In addition to environmental implications, there is an increasing interest in how exposure to plastics may impact human health, but our understanding is still limited. Only recently it was shown that plastics can accumulate also in the human brain.

Plastic particles smaller than 5000 nm in diameter are called microplastics, and the smallest plastic particles with a diameter of less than 1000 nm are called nanoplastics. The small size of nanoplastics enables them to interact with various cell types, and other particles or biological mass, such as bacteria. Compared to microplastics, nanoplastics have larger adsorption capacity and penetrate through biological barriers more easily. This makes them potentially more harmful and a compelling target for research in the field of neurobiology.

The Cellular Neurobiology research group led by professor Katja Kanninen at the A. I. Virtanen Institute for Molecular Sciences investigates how environmental stressors affect brain health and cellular functions. In a recent study published in a special issue of NanoImpact, the group utilised primary neuron cell cultures to shed light on the effects of various sizes of polystyrene nanoplastics. Their study is among the few that focuses on small particles at low doses, to examine their potential subtle effects on brain cells.

The study demonstrated that polystyrene nanoplastics can be internalised and accumulated inside neurons. Morphological and gene expression analyses pointed to more pronounced effects of smaller particles compared to larger ones, all within nanoplastics scale.

“It is important to understand that not only the concentration and material, but also the size of the particles matters,” highlights Doctoral Researcher Veronika Górová, the first author of the article. “With decreasing nanoparticle size, we observed more pronounced, although still relatively subtle changes.”

“In the future it would be interesting to have a look at the effects with more complex models and prolonged exposures, to get closer to the real-world scenario,” Górová adds.

The study expands the current knowledge of the effects of nanoparticles in the brain and underscores the need to examine low-dose exposure and small-in-size particles for their potential health risks.

Research article:

Veronika Górová, Thuy Thi Lai, Alexey M. Afonin, Kore Nemeth, Anssi Pelkonen, Tarja Malm, Pasi Jalava, Riikka Lampinen, Katja M. Kanninnen, Polystyrene nanoplastics modulate neurite length in a size-specific manner, NanoImpact, Volume 41, 2026, 100614, ISSN 2452-0748, https://doi.org/10.1016/j.impact.2026.100614.

The research group is a member of the multidisciplinary Neuroscience Research Community (NEURO RC) at the University of Eastern Finland. NEURO RC aims to understand the disease-specific and common molecular mechanisms underlying neurodegenerative diseases and epilepsy and to identify novel biomarkers and therapeutic approaches for their prevention and cure. NEURO RC integrates biological neurosciences with data sciences, neuro-innovations, and neuro-ethics. Learn more and connect with NEURO RC: https://www.uef.fi/en/research-community/neuroscience-neuro