Microplastic Particles Are Continuously Accumulating in the Human Brain

演化之聲
Mar 13
3 min read

Updated: 18 hours ago

In recent years, the rapid increase in environmental microplastics and nanoplastics has raised growing concern about the potential health risks associated with the accumulation of plastic particles in the human body. As concentrations of these particles in the environment continue to rise, understanding how they enter and persist within human tissues has become an important scientific question.

A research team led by Alexander J. Nihart analyzed human liver, kidney, and brain tissue samples obtained from the University of New Mexico. The samples included specimens collected in 2016 and 2024. In addition, the researchers obtained brain tissue samples collected between 1997 and 2013 from several tissue banks located on the east coast of the United States. These samples were examined to determine the concentrations of microplastic particles present in different organs.

The results revealed clear differences in microplastic levels between the earlier and more recent samples. In liver tissue, the median concentration of microplastics was approximately 100 µg per gram of tissue in 2016, but increased to about 433 µg/g in 2024. A similar pattern was observed in the brain. Median concentrations in brain tissue rose from roughly 3,345 µg/g in 2016 to 4,917 µg/g in 2024. These findings indicate that over an eight-year period, the concentration of plastic particles increased approximately 4.3-fold in the liver and about 1.5-fold in the brain. Among the detected polymers, polyethylene (PE) was the most abundant type.

Comparison of microplastics concentration in tissues collected in 2016 and 2024: liver, kidney, and brain. Each circle represents one tissue sample（Image source：Nihart AJ et al， CC BY-NC-ND 4.0 ）

Polyethylene (PE) is the most abundant polymer across all tissues（Image source：Nihart AJ et al， CC BY-NC-ND 4.0 ）

By comparison, brain tissue samples collected from eastern United States tissue banks between 1997 and 2013 showed much lower levels of microplastics, with a median concentration of about 1,254 µg/g. Statistical regression analysis further revealed a consistent upward trend in the concentrations of several polymers—including polyethylene, polypropylene, polyvinyl chloride, and styrene-butadiene rubber—from 1997 to 2024.

The researchers also examined brain tissue from twelve individuals diagnosed with dementia between 2019 and 2024. In these cases, the median concentration of microplastics reached 26,076 µg/g, approximately 5.3 times higher than that measured in normal brain samples collected in 2024. This observation suggests that there may be a potential relationship between microplastic accumulation and neurodegenerative conditions.

Regression analysis showing the increase of microplastics concentration in the brain over time。NC (Duke Kathleen Price Bryan Brain Bank in North Carolina)、MA (Harvard Brain Tissue Resource Center in Massachusetts)、MD (National Institute of Child Health and Human Development Brain and Tissue Bank at the University of Maryland)、NM (University of New Mexico) （Image source：Nihart AJ et al， CC BY-NC-ND 4.0 ）

Overall, the study indicates that microplastic particles can accumulate within the human brain, and that their concentrations are higher in brain tissue than in organs such as the liver or kidneys. The results also raise the possibility that elevated levels of plastic particles could be associated with neurological disease. As global plastic production and environmental contamination continue to increase, an important question emerges: whether the human brain is gradually becoming a reservoir for plastic particles. Addressing this possibility will require deeper investigation and the development of strategies to reduce exposure and prevent further accumulation.