"Microplastics in Nature: Deadly Poison to Brain Nerves"

It has been revealed that ingesting secondary microplastics encountered in nature acts as a fatal toxic substance to brain nerves.

Stock photo of microplastics. Not related to the article.

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The Daegu Gyeongbuk Institute of Science and Technology (DGIST) announced on the 12th that the research team led by Seongkyun Choi, head of the Core Protein Resource Center, in collaboration with Professor Jinkyu Park's team at Kyungpook National University, successfully simulated the process of plastics entering the environment transforming into secondary microplastics at the laboratory level, and demonstrated that continuous ingestion of these acts as a neurotoxic substance in the brain.

Plastic waste, amounting to 8 million tons annually, breaks down into very small fragments due to ultraviolet rays and waves, turning into secondary microplastics. These are ingested by lower organisms such as plankton, eventually posing a threat to humans at the top of the food chain.

The research team confirmed the harmfulness of secondary microplastics generated by natural weathering from plastics leaked into the environment. First, to replicate a natural environment, they artificially produced secondary microplastics by subjecting crushed microplastics to ultraviolet radiation and physical impact for seven days, simulating natural weathering. Through this, they established a generation model that mimics the chemical and physical changes occurring to plastics leaked into the environment due to environmental factors such as ultraviolet rays and waves at the laboratory level.

Subsequently, to assess the toxicity of secondary microplastics, an experiment was conducted where microplastics smaller than 100㎛ were orally administered to rats for seven days. As a result, the group ingesting secondary microplastics showed increased expression of inflammatory proteins related to neurodegeneration and cell death, and decreased expression of anti-inflammatory proteins in the external brain tissue.

Schematic diagram of physicochemical changes in secondary microplastics and changes in brain inflammatory responses. Image source: Provided by DGIST

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Furthermore, to investigate the effect of naturally weathered secondary microplastics on microglia, which regulate inflammatory responses in the brain, experiments were conducted using the human microglial cell line (HMC-3). The results confirmed that secondary microplastics stimulate microglia responsible for regulating brain inflammation, inducing inflammatory responses in the brain. This suggests that secondary microplastics can act as potential neurotoxic substances in the brain.

Director Choi stated, “We have, for the first time, identified through proteomics-based analysis that plastics leaked into the environment undergo accelerated weathering to become secondary microplastics, which can act as neurotoxic substances increasing inflammation and cell death in the brain.” He added, “The fact that secondary microplastics, which can be exposed to in the natural environment, induce more severe inflammatory responses in the brain raises serious concerns about the toxicity of microplastics.”

The results of this study were published online in the international environmental science journal Environmental Research.

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