by Human brain samples collected at an autopsy in early 2024 contained more plastic shards than samples collected eight years earlier, according to a preliminary print posted online in May. A preprint is a study that has not yet been peer-reviewed and has not been published in a journal.
“The concentration we saw in the brain tissue of normal people, whose average age was about 45 or 50 years old, was 4,800 micrograms per gram, or 0.5% by weight,” said lead study author Matthew Campen , professor with regents. in pharmaceutical sciences at the University of New Mexico in Albuquerque.
“Compared to autopsy brain samples from 2016, that’s about 50% higher,” Campen said. “That would mean our brains today are 99.5% brain and the rest plastic.”
That increase, however, only reflects exposure and does not provide information about brain damage, said Phoebe Stapleton, an associate professor of pharmacology and toxicology at Rutgers University in Piscataway, New Jersey, who was not involved in the preliminary print.
“It is not clear whether these particles are fluid in life, entering and leaving the brain, or if they collect in neurological tissues and promote disease,” she said in an email. “Further research is needed to understand how the particles might be interacting with the cells and whether it has a toxicological consequence.”
The brain samples contained between 7 and 30 times more tiny plastic shards than the cadaver kidney and liver samples, according to the preprint.
“Studies have found these plastics in the human heart, the great blood vessels, the lungs, the liver, the testes, the gastrointestinal tract and the placenta,” said pediatrician and biology professor Dr. Philip Landrigan, director of the Program for Global Community Health and the Common Good and the Global Observatory on Planetary Health at Boston College.
“It’s important not to scare people, because the science in this space is still evolving, and no one in the year 2024 is going to live without plastic,” said Landrigan, who was not involved in the preprint.
“I tell people, ‘Listen, there are some plastics you can’t escape. You’re not going to find a mobile phone or computer that doesn’t have plastic in it.’ But try to minimize your exposure to plastic that you can avoid, such as plastic bags and bottles.”
The American Chemistry Council, an industry association, told CNN that while “several studies on microplastics have garnered headlines recently, just last month the FDA noted, ‘Current scientific evidence does not show that the levels of microplastics or nanoplastics detected in foods at risk. human health.’
“Ongoing research not only helps address the current data gaps in our understanding of exposure to microplastics but also aims to develop improved tools to measure the toxicity of microplastics to humans,” said Kimberly Wise White, Vice President of the Council for Regulatory and Scientific Affairs.
“This work is important given the unvalidated methods often applied by researchers that can lead to unreliable or misleading results, the complex nature of microplastics, and the many variables that can affect human health, ” she said.
Nanoplastics ‘hijack’ their way into the brain
For the study, the researchers examined brain, kidney and liver tissue from 92 people who underwent forensic autopsies to verify the cause of death in 2016 and 2024. Brain tissue samples were collected from the frontal cortex, the area of the brain associated with thinking and reasoning, and those most affected by frontotemporal dementia (FTD) and later stages of Alzheimer’s disease.
“Based on our observations, we think the brain is pulling in the smallest nanostructures, like 100 to 200 nanometers long, but some of the larger particles that are between one micrometer and five micrometers end up in the liver and kidneys, ” Campen said.
Microplastics are fragments that can range from less than 0.2 inches (5 millimeters) or about the size of a pencil eraser, to 1 nanometer. A strand of human hair is about 80,000 nanometers wide, according to the US Environmental Protection Agency. Anything smaller is a nanoplastic that must be measured in billionths of a meter.
Nanoplastics are the worst plastics for human health, experts say, because the minuscule pieces can take up residence inside individual cells.
“Somehow these nanoplastics find their way through the body and get to the brain, crossing the blood-brain barrier,” Campen said. “Plastics love fats, or lipids, so one theory is that plastics are hijacking their way with the fats we eat and then being delivered to the organs that really like lipids – chief among them the brain. “
The human brain is about 60% fat by weight, far more than any other organ. Essential fatty acids, such as omega 3s, are vital for the strength and performance of brain cells. Since the human body cannot produce essential fatty acids on its own, they must come from food or supplements.
Diet is the main route of exposure to microplastics and nanoplastics, said Landrigan, who is the lead author of a March 2023 report from the Minderoo-Monaco Commission on Plastics and Human Health, a global consortium of scientists, health care workers and policy makers. analysts responsible for plastics that follow from creation to final product.
In that report, the consortium determined plastics are associated with harm to human health at every stage of the plastic life cycle.
“There are also some microplastics in the air,” Landrigan said. “For example, when people drive down the highway and their tires scrape the surface of the highway, a certain amount of microplastic particles are thrown into the air.
“If you live near the coast, some of the microplastic particles in the ocean are blown into the air by wave action,” he said. “So ingestion is probably the main route, but inhalation is also an important route.”
Plastics linked to cancer
Polyethylene, which is used in plastic bags, films and bottles and is not biodegradable, was the most common type of plastic found in tissue samples. It was found in greater quantities in the brain than in the liver or kidney, according to the preliminary print.
Polyethylene was the most common type of polymer found in human and dog testicles as well, according to an August 2024 study by Campen and his team.
The production of various forms of polyethylene, such as polyethylene terephthalate (PET) plastics, is the largest contributor to the release of the solvent 1,4-dioxane into the environment, according to industry data collected by Protect Our Health, an environmental advocacy group. . .
The US National Toxicology Program and the International Agency for Research on Cancer consider 1,4-dioxane to be potentially carcinogenic to humans. In 2023, the EPA issued a draft report stating that the solvent poses an “unreasonable risk of harm to the health” of plastics workers and community residents whose drinking water is polluted by discharge from PET plastic factories.
“The biggest question is, ‘Okay, what are these particles doing for us?’ There’s honestly a lot we don’t know yet,” Landrigan said. “What we know with real certainty is that these microplastic particles are like Trojan horses – they carry with them thousands of chemicals that are in plastics and some of them are very bad actors.”
By invading individual cells and tissues in major organs, nanoplastics can disrupt cellular processes and deposit endocrine-disrupting chemicals such as biphenols, phthalates, flame retardants, heavy metals and per- and polyfluorinated substances, or PFAS .
Endocrine disruption affects the human reproductive system, causing genital and reproductive malformations as well as female infertility and reduced sperm count, according to the Endocrine Society.
“We have some pretty good indications that microplastics and nanoplastics are causing harm, although we are far from knowing the full extent of that harm,” Landrigan said. “I would say we have enough information here that we need to start taking defensive action.”
Learn how to use less plastic
There are many steps individuals can take to reduce their exposure to plastics and their plastic footprint, experts say.
“It’s hard to avoid foods wrapped in plastic wrap but make sure to remove the food from the plastic wrap before you cook or microwave it,” said Landrigan. “When you go plastic, that accelerates the movement of microplastics out of the wrapper and into the food.
Invest in a zippered fabric bag and ask the dry cleaner to return your clothes instead of those thin plastic sheets, suggested the Natural Resources Defense Council, an environmental advocacy group. Bring a travel mug to the local coffee shop to take out and bring silverware to the office to cut down on plastic cups and utensils.
“Don’t use plastic bags when you go shopping. Use a cloth bag or a paper bag or a recycling bag. Try to avoid plastic water bottles, if you can,” said Landrigan.
A March 2024 study found that 1 liter of bottled water contained an average of 240,000 plastic particles from seven types of plastics — the equivalent of two standard-sized bottles of water purchased by consumers. About 90% of these were nanoplastics.
“Use a metal or glass drinking cup instead of a plastic cup. Store your food in glass containers rather than plastic,” said Landrigan. “Work in your local community to ban plastic bags, as many communities across the United States have now done. There is a lot you can do.”
For more CNN news and newsletters create an account at CNN.com
