Human brain samples collected from autopsies beginning in 2024 contain a worrying amount of tiny pieces of plastic, a new study shows.
"The concentrations we saw in the brain tissue of individuals who were about 45 or 50 years old on average were 4,800 micrograms per gram, or 0.5 percent by weight," said lead study author Matthew Kampen, professor of pharmaceutical sciences at University of New Mexico, Albuquerque.
"Compared to brain samples from autopsies in 2016, this is about a 50% increase. Our brains today are 99.5% brain and the rest is plastic," he added, quoted by CNN.
It is not entirely clear whether these particles are liquid, how they enter and leave the brain, how they accumulate in neurological tissues and contribute to disease. Further research is needed to understand how the particles may interact with cells and whether this has toxicological consequences.
The brain samples contained 7 to 30 percent more tiny plastic particles than the kidney and liver samples of the autopsied deceased, the study found.
"Studies have found these plastics in the human heart, large blood vessels, lungs, liver, testes, gastrointestinal tract and placenta," said pediatrician and professor of biology Dr. Philip Landrigan, director of the Global Public Health Program and common good at Boston College.
"It's important not to scare people because the science in this area is still developing and no one in 2024 can live without plastic," Landrigan said, adding:
"I tell people, 'Listen, there are some plastics you can't escape. You won't get a cell phone or computer that doesn't contain plastic. But try to minimize exposure to plastic you can avoid, such as plastic bags and bottles.”
For the purpose of the study, experts examined brain, kidney and liver tissue from 92 people who underwent autopsies to determine the cause of death between 2016 and 2024. Brain tissue samples were taken from the frontal cortex, the area of the brain associated with with thinking and reasoning most affected by frontotemporal dementia (FTD) and the later stages of Alzheimer's disease.
"Based on our observations, we think that the brain attracts the smallest nanostructures, for example 100-200 nanometers in length, while some of the larger particles, which are one to five micrometers in length, end up in the liver and kidneys," Campen said.
Microplastics are fragments that can range from 5 millimeters - the size of a pencil eraser - to 1 nanometer. According to the US Environmental Protection Agency, a single human hair is about 80,000 nanometers wide. Anything less is nanoplastic. It is measured in billionths of a meter.
Nanoplastics are the most worrisome for human health, experts say, because the tiny particles can lodge in individual cells.