BEIJING -- A group of Chinese researchers has confirmed the presence of microplastics and nanoplastics in the living human brain and systematically revealed their distribution characteristics in both brain tumor tissues and healthy brain tissues, according to the Beijing Tiantan Hospital affiliated to Capital Medical University on Tuesday.

Microplastics and nanoplastics are emerging global contaminants of concern owing to their ability to penetrate human tissues and their detection in several human organs, including the brain. But their concentrations in, and effects on, this organ remain largely unexplored.

The researchers from the Beijing Tiantan Hospital, Peking Union Medical College Hospital, and the Chinese Research Academy of Environmental Sciences spent 4 years analyzing 156 diseased brain samples from 113 patients with brain tumors, along with 35 healthy brain samples from 5 post-mortem donors.

The results showed that the microplastics and nanoplastics were detected in 99.4 percent of diseased brain samples and 100 percent of healthy brain samples.

A higher concentration of microplastics and nanoplastics was observed in peritumoral brain tissues than in healthy brain tissues, according to their research article published in the journal Nature Health.

Meanwhile, the study found that nanoplastics accounted for more than half of the total plastic burden, suggesting that smaller particles may be more likely to cross the blood-brain barrier and enter brain tissue, Beijing Tiantan Hospital noted.

To explain why these plastic particles are present in brain tissue, the researchers have proposed two possible hypotheses.

One is that the plastic particles might primarily remain within the brain's vascular system. The other hypothesis is that under brain tumor conditions, the blood-brain or blood-tumor barrier might be compromised, potentially allowing plastic particles to cross these barriers, enter the brain parenchyma and accumulate there.

They investigated the possible sources of these plastic particles. Among the brain tumor patients, factors such as preoperative injection frequency, body mass index, age, frequency of cosmetic use, and the use of plastic food wrap were found to be associated with higher microplastic abundance.

The study identified the distribution characteristics of microplastics and nanoplastics in the human brain and their correlations with pathological barrier status and tumor proliferation indicators, said Chen Xiaolin, Chief Physician of the Neurosurgery Center, Beijing Tiantan Hospital, adding that it cannot directly prove that these particles cause the development, progression, or poor prognosis of brain tumors.