Recent research has revealed that brain samples collected in early 2024 contained an average of about 0.5% plastic by weight, raising significant concerns about the accumulation of microplastics in critical human organs.

This discovery is part of a growing body of scientific evidence that microplastics, tiny fragments smaller than 5mm, are infiltrating vital areas of the human body, including the brain, lungs, placentas, reproductive organs, livers, kidneys, joints, blood vessels, and bone marrow.

Given the research findings, “it is now imperative to declare a global emergency” to deal with plastic pollution, said Sedat Gündoğdu, who studies microplastics at Cukurova University in Turkey.

Humans are exposed to these microplastics through widespread plastic pollution in the air, water, and food. Although the health risks of microplastics within the body are not yet fully understood, recent studies suggest they may increase the risk of various conditions, including oxidative stress, cell damage, inflammation, and cardiovascular disease. Animal studies have also linked microplastics to fertility issues, cancers, disrupted endocrine and immune systems, and impaired learning and memory.

Despite these alarming findings, there are currently no governmental standards for plastic particles in food or water in the United States. The Environmental Protection Agency (EPA) is developing guidelines for measuring microplastics and has been awarding grants since 2018 to develop methods for quickly detecting and quantifying them.

Finding microplastics in more and more human organs “raises a lot of concerns”, given what we know about health effects in animals, studies of human cells in the lab, and emerging epidemiological studies, said Bethanie Carney Almroth, an ecotoxicologist at the University of Gothenburg in Sweden. “It’s scary, I’d say.”

One particularly concerning study, still undergoing peer review and posted online by the National Institutes of Health, found a significant accumulation of microplastics in brain samples. Researchers examined the livers, kidneys, and brains of autopsied bodies and discovered that all contained microplastics, with the 91 brain samples containing on average 10 to 20 times more plastic than the other organs.

According to the study’s lead author, Matthew Campen, a toxicologist and professor at the University of New Mexico, these results were shocking.

The researchers found that 24 of the brain samples, which were collected in early 2024, measured on average about 0.5% plastic by weight.

“It’s pretty alarming,” Campen said. “There’s much more plastic in our brains than I ever would have imagined or been comfortable with.”

The study describes the brain as “one of the most plastic-polluted tissues yet sampled”.

The pre-print brain study led by Campen also hinted at a concerning link. In the study, researchers looked at 12 brain samples from people who had died with 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 brain can stuff in without it causing some problems,” Campen said.

The study also found that the quantity of microplastics in brain samples from 2024 was about 50% higher than in samples dating back to 2016, suggesting that microplastics are accumulating in human brains at a rate similar to their increase in the environment. Most of the organs used in the study were sourced from the medical investigator’s office in Albuquerque, New Mexico, which handles cases of untimely or violent deaths.

“You can draw a line – it’s increasing over time. It’s consistent with what you’re seeing in the environment,” Campen said.

Further research has revealed that microplastics are not only found in humans but have also been detected in the brains of various animal species, making it unsurprising that humans could be similarly affected.

When it comes to these insidious particles, “the blood-brain barrier is not as protective as we’d like to think”, Almroth said, referring to the series of membranes that keep many chemicals and pathogens from reaching the central nervous system.

A recent study published in the Journal of Hazardous Materials detected microplastics in all 16 bone marrow samples examined, marking the first paper of its kind. These samples contained polystyrene, commonly used in packing materials, and almost all contained polyethylene, found in everyday items like clear food wrap and detergent bottles.

“The potential health effects are concerning, especially considering the unknown long-term consequences of microplastics accumulating in sensitive tissues like the reproductive organs,” said Ranjith Ramasamy, the study’s lead author and a medical researcher and urologist at the University of Miami.

Another study involving 45 patients undergoing hip or knee surgery in Beijing, China, discovered microplastics in the membranous lining of every joint examined.

Similarly, a study published in May in the journal Toxicological Sciences found microplastics in all 23 human and 47 canine testicles studied, with human samples containing nearly three times the concentration of microplastics compared to those from dogs. Notably, higher quantities of certain plastics, like polyethylene, were correlated with lower testicular weights in dogs.

Further evidence of microplastic contamination was found in a study published in June in the International Journal of Impotence Research, which detected plastic particles in the penises of four out of five men undergoing penile implants for erectile dysfunction. Another study by a Chinese research team published in May found microplastics in the semen of all 40 participants, with an Italian study from earlier in the year reporting similar findings.

Microplastics have also been found in human placentas. A study published in the May issue of Toxicological Sciences reported finding micro- and nanoplastics in all 62 placental samples examined, though concentrations varied widely.

In Italy, researchers followed 312 patients who had fatty deposits, or plaques, removed from their carotid arteries. Nearly 60% of these patients had microplastics in their arteries, and they were 2.1 times more likely to experience a heart attack, stroke, or death over the next 34 months compared to those without microplastics.

The Food and Drug Administration says in a statement on its website that “current scientific evidence does not demonstrate that levels of microplastics or nanoplastics detected in foods pose a risk to human health.”

While much remains unknown about the impacts of microplastic accumulation in humans, researchers suggest that individuals reduce their exposure by avoiding plastic use in food preparation, especially when microwaving; drinking tap water instead of bottled water; and minimising dust accumulation, which often contains microplastics. Some experts also recommend reducing meat consumption, particularly processed products.

Leonardo Trasande, a medical researcher at New York University, emphasised that while the full effects of microplastic accumulation in humans are not yet clear, the harmful impacts of chemicals used in plastics, such as phthalates, are well-established. A study co-authored by Trasande found that exposure to phthalates increased the risk of cardiovascular disease and death in the United States, leading to over $39 billion in lost productivity annually.

Microplastic particles can be contaminated with and carry such chemicals into the body. “The micro- and nanoplastics may be effective delivery systems for toxic chemicals,” Trasande said.

The American Chemistry Council, representing plastic and chemical manufacturers, did not directly address the recent studies on microplastics in human organs. However, Kimberly Wise White, a vice president with the group, stated that “the global plastics industry is dedicated to advancing the scientific understanding of microplastics.”

In response to growing concerns, the United Nations Environment Assembly agreed two years ago to work toward a global treaty to end plastic pollution, a process that is ongoing. Recent news reports suggest that the Biden administration has indicated support for measures to reduce global plastic production, which researchers say is critical to addressing the microplastic pollution problem.

“There’s nowhere left untouched from the deep sea to the atmosphere to the human brain,” Almroth said.

 

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