Microplastics penetrate brain tissue, study shows: ‘There is no place that remains untouched’
Mounting scientific evidence shows that microplastics accumulate in key human organs, including the brain, leading researchers to call for more urgent action to tackle plastic pollution.
Research has shown that the human body contains small shards and specks of plastic. lungsplacentas, reproductive organs, livers, kidneys, knee and elbow joints, blood vessels and bone marrow.
Given the research findings, it is now “necessary to declare a global emergency” to tackle plastic pollution, it said Sedat Gundogduwho studies microplastics at Cukurova University in Turkey.
People are exposed to microplastics – defined as fragments smaller than 5mm in diameter – and the chemicals used to make plastic through widespread plastic pollution in the air, water and even food.
The health risks of microplastics in the human body are not yet well understood. Recent studies are only beginning to suggest that they may increase the risk of several conditions, such as oxidative stresswhich can lead to cell damage and inflammation, as well as cardiovascular diseases.
Animal studies have also shown that microplastics are linked to fertility problemsvarious forms of cancer, a disturbed endocrine and immune system, and reduced learning and memory ability.
There are currently no government standards for plastic particles in food or water in the United States. The Environmental Protection Agency is working on drawing up guidelines to measure them and has been providing grants since 2018 to develop new ways to rapidly detect and quantify them.
The finding of microplastics in more and more human organs “raises significant concerns,” given what we know about health effects in animals, studies of human cells in the lab, and emerging epidemiological studies, he said. Bethanie Carney Almrothecotoxicologist at the University of Gothenburg in Sweden. “It’s scary, I would say.”
‘Quite alarming’
In one of the latest studies to emerge – a pre-print article that is still undergoing peer review – posted online by the National Institutes of Health – the researchers found a particularly worrying accumulation of microplastics in brain samples.
An examination of the livers, kidneys and brains of autopsied bodies found that they all contained microplastics, but the 91 brain samples contained on average about 10 to 20 times more than the other organs. The results came as a shock, the study’s lead author said Matthew Campentoxicologist and professor of pharmaceutical sciences at the University of New Mexico.
The researchers found that 24 of the brain samples, collected in early 2024, contained an average of about 0.5% plastic.
“It’s quite alarming,” Campen said. “There’s a lot more plastic in our brains than I ever thought or felt comfortable with.”
The study describes the brain as “one of the most plastic-polluted tissues studied to date.”
The pre-print brain study led by Campen also hinted at a worrying link. In the study, researchers looked at 12 brain samples from people who had died of dementia, including Alzheimer’s disease. These brains contained up to 10 times more plastic by weight than healthy samples.
“I don’t know how much more plastic our brains can cram in without it causing problems,” Campen said.
The paper also found that the amount of microplastics in brain samples from 2024 was about 50 percent higher than the total in samples dating back to 2016, suggesting that the concentration of microplastics in human brains is rising at a rate similar to that in the environment. Most of the organs came from the Office of the Medical Investigator in Albuquerque, New Mexico, which studies premature or violent deaths.
“You can draw a line – it increases over time. It matches what you see in the environment,” Campen said.
Many other studies have shown that microplastics are present in the brains of other species, so it is not surprising that this is also true for humans, says Almroth of the University of Gothenburg, who was not involved in the study.
When it comes to these sneaky particles, “the blood-brain barrier is not as protective as we would like to think,” Almroth said, referring to the series of membranes that keep many chemicals and pathogens from reaching the central nervous system.
Explosion of research
Adding to concerns about accumulation in the human body, the Journal of Hazardous Materials writes a study published last month that found microplastics in all 16 bone marrow samples tested, the first paper of its kind. All of the samples contained polystyrene, used to make packaging chips and electronics, and nearly all contained polyethylene, used in clear food containers, detergent bottles and other common household products.
Another one recent article In a study of 45 patients undergoing hip or knee surgery in Beijing, China, microplastics were found in the membranes of every individual hip or knee joint examined.
A study published In a May 15 issue of the journal Toxicological Sciences, researchers found microplastics in all 23 human and 47 dog testicles studied, with human samples found to have nearly three times the concentration of those from dogs. Higher amounts of certain types of plastic particles — including polyethylene, the main component of plastic water bottles — correlated with lower testicle weights in dogs.
Another one paper that appeared On June 19, the International Journal of Impotence Research found plastic particles in the penises of four out of five men who received penile implants to treat erectile dysfunction.
“The potential health effects are concerning, especially given the unknown long-term consequences of microplastics accumulating in sensitive tissues such as the reproductive organs,” said Ranjith Ramasamy, lead author of the study and a medical researcher and urologist at the University of Miami.
Meanwhile, there is a Chinese group a study published in May, where small amounts of microplastics were found in the semen of all 40 participants. A Italian paper from a few months earlier reported similar results.
A handful of studies have now also found contamination in human placentas. study that appeared The May issue of Toxicological Sciences reported the discovery of micro- and nanoplastics in all 62 placenta samples, although concentrations varied widely.
In Italy, researchers followed 312 patients with fatty deposits, or plaques, removed from their carotid arteryNearly six in ten people had microplastics and these people fared worse than those who did not have microplastics: over the next 34 months they were 2.1 times more likely to have a heart attack or stroke, or to die.
‘Nowhere left untouched’
The Food and Drug Administration says in a statement on its website that “current scientific evidence does not show that the levels of microplastics or nanoplastics found in foods pose a risk to human health.”
Still, researchers say people should try to reduce their exposure by avoiding the use of plastics in food preparation, especially microwaving; drinking tap water instead of bottled water; and trying to prevent the buildup of dust contaminated with plastic. Some researchers advise less meat, especially processed products.
Leonardo Trasande, a medical researcher at New York University, said much remains unknown about the impact of microplastic accumulation in humans. However, the negative health effects of chemicals used in plastics, such as phthalates, are better established, he said. A study he co-authored found exposure to phthalates has increased the risk of cardiovascular disease and death in the United States, resulting in annual productivity losses of $39 billion or more.
Microplastic particles can be contaminated with such chemicals and carry them into the body. “The micro- and nanoplastics can be effective delivery systems for toxic chemicals,” Trasande said.
The American Chemistry Council, which represents plastics and chemical manufacturers, did not immediately respond to questions about the recent studies finding microplastics in human organs. Kimberly Wise White, a vice president of the group, noted that “the global plastics industry is committed to advancing scientific understanding of microplastics.”
The United Nations Environment Assembly agreed two years ago to begin working on a global treaty to end plastic pollution, a process that ongoing.
Multiple news reports suggest that the Biden administration has indicated over the past week that the US delegation involved in the talks will support measures to reduce global plastic production, which researchers say is crucial to get the problem under control.
“There is no area left untouched, from the deep sea to the atmosphere to the human brain,” Almroth said.
This story is co-published with the New Ledea journalistic project of the Environmental Working Group