Microplastics found in nose tissue at base of brain, study says

By Sandee LaMotte, CNN

(CNN) — Tiny plastic shards and fibers were found in the nose tissue of human cadavers, according to a small new study.

The threads and microplastic pieces were discovered in the olfactory bulb, the part of the nose responsible for detecting odors that sits at the base of the brain.

“Once present in this structure, there can be translocation to other regions of the brain,” said lead study author Luís Fernando Amato-Lourenço, a postdoctoral microplastics researcher at the Free University of Berlin, in an email.

“Translocation depends on several factors, including the shape of the particle, whether it is a fiber or a fragment, its size, and the body’s defense mechanisms.”

Due to their smaller size and shape, Amato-Lourenço added, particles are more likely than fibers to bypass microglia cells in the blood-brain barrier, a membrane that protects the brain and spinal cord from many harmful substances.

“This is a really interesting study,” said Phoebe Stapleton, an associate professor of pharmacology and toxicology at Rutgers University in Piscataway, New Jersey, who was not involved in the study.

“I’m not really surprised,” Stapleton added. “I really do think that plastics are going to be in every place in the body that we look. This is just more evidence.”

When it comes to studies about plastics and human health, “there is a debate within the scientific community about whether the current body of evidence sufficiently reflects real-world implications,” said Betsy Bowers, executive director of the EPS Industry Alliance, a trade association for the expanded polystyrene industry.

“The lack of consensus stems from sufficient quality assurance, involving issues like nano plastics’ definitions, precision and bias for test methodologies, dose-response relationships, and risk versus exposure assessments,” Bowers said in an email.

A growing amount of plastic in the body

A flurry of recent studies have discovered microplastics and nanoplastics in human brain tissue, the testes and the penis, human blood, lung and liver tissues, urine and feces, mother’s milk and the placenta.

In the first analysis to illustrate harm to human health, a March study found people with microplastics or nanoplastics in their carotid artery tissues were twice as likely to have a heart attack, stroke or die from any cause over the next three years than people who had none.

Microplastics are polymer fragments that can range from less than 0.2 inch (5 millimeters) down to 1/25,000th of an inch (1 micrometer). Anything smaller is a nanoplastic that must be measured in billionths of a meter.

Such minuscule particles can invade individual cells and tissues in major organs, experts say, potentially interrupting cellular processes and depositing endocrine-disrupting chemicals such as bisphenols, phthalates, flame retardants, perfluoroalkyl and polyfluoroalkyl substances or PFAS, and heavy metals.

“The chemicals can be carried to your liver and your kidney and your brain and even make their way across the placental boundary and end up in an unborn child,” Sherri “Sam” Mason, director of sustainability at Penn State Behrend in Erie, Pennsylvania, told CNN in an earlier interview. She was not involved in the new study.

Unable to see the smallest particles

The new study, published Monday in the journal JAMA Network Open, found microplastics in the olfactory bulbs of eight of 15 cadavers that ranged in size from 5.5 micrometers, or 0.000217 of an inch, to 26.4 micrometers, or 0.001039 of an inch. For comparison, a strand of human hair is about 80,000 nanometers wide, or 0.00315 of an inch, according to the US Environmental Protection Agency.

Due to the type of analysis used, the study was not able to look for nanoparticles, which are 1,000th the average width of a human hair.

Still, the dimensions of the plastics found in the cadavers’ olfactory bulbs were “much smaller than those of several other studies that have determined the presence of microplastics in human organs, such as the placenta, kidneys, liver, etc.,” Amato-Lourenço said.

The study was not able to determine the source of exposure or why some of the deceased might have evidence of plastic in their noses while others did not, he said.

“What we do know from studies published in the literature is that when there is local inflammation of the mucosa (lining in the nasal cavity), it can be easier for microplastics to penetrate,” Amato-Lourenço said. “A large proportion of the microplastics present in the air are fibers that come from clothing with synthetic fabrics and everyday objects such as carpets, curtains, etc.”

Polypropylene was the predominant plastic found in the olfactory bulbs of the cadavers. One of the widely used plastics, polypropylene is generally considered safe for human use. However, an April 2023 study found that microplastics made of polypropylene appeared to exacerbate the advance of breast cancer.

Limiting your exposure to plastic

There are steps one can take to reduce exposure to phthalates and other chemicals in food and food packaging products, according to the American Academy of Pediatrics’ policy statement on food additives and children’s health.

“One is to reduce our plastic footprint by using stainless steel and glass containers, when possible,” said Dr. Leonardo Trasande, director of environmental pediatrics at NYU Langone Health, in an earlier interview with CNN.

“Avoid microwaving food or beverages in plastic, including infant formula and pumped human milk, and don’t put plastic in the dishwasher, because the heat can cause chemicals to leach out,” said Trasande, who is also the lead author for the AAP’s policy statement.

“Look at the recycling code on the bottom of products to find the plastic type, and avoid plastics with recycling codes 3, which typically contain phthalates,” he added.

Phthalates, known as “everywhere chemicals” because they are so common, are one of the chemicals used in manufacturing known to be hormone disruptors.

Cut down on the use of disposable plastics, suggests the Natural Resources Defense Council, an environmental advocacy group. Other suggestions include bringing reusable bags to the grocery store. Invest in a zippered fabric bag and ask the dry cleaner to return your clothes in that instead of those thin sheets of plastic. Bring a travel mug to the local coffee store for takeout and silverware to the office, cutting back on plastic cups and utensils.

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