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Chewing Gum Releases Microplastics Into Your Mouth, Scientists Warn

A SINGLE piece of chewing gum releases thousands of toxic microplastics into your mouth to be swallowed, scientists have warned.

Newsweek

Mar 25, 2025 | 857 words | ★★☆☆☆

This is the warning of researchers from the University of California, Los Angeles (UCLA) who experimented to see how many microplastics the polymer-based treats might let out.

Microplastic (smaller than 5 millimeters in size) and nanoplastic (under 0.001 millimeters) particles have become ubiquitous in the environment and can get into the very food we eat.

These particles have been found in various bodily organs—including the brain, kidney, liver, placenta and testes—with scientists estimating that humans may consume as many as tens of thousands of microplastic pieces each year.

Scientists are concerned about the impact of microplastics on health; with studies on animals and human cells suggesting that microplastic particles could be causing us harm.

"Our goal is not to alarm anybody," said paper author and engineer Professor Sanjay Mohanty. "Scientists don't know if microplastics are unsafe to us or not.

"There are no human trials. But we know we are exposed to plastics in everyday life—and that's what we wanted to examine here."

In their study, Mohanty and his colleagues conducted a series of experiments involving 10 different brands of commercially-available gum—five natural and five synthetic.

Natural gum products are made with a rubber base made of plant-based polymers like chicle or other tree saps, while their synthetic counterparts use petroleum-based polymers.

First, each piece of gum was chewed by a single subject for four minutes, with saliva samples collected every 30 seconds until the end, when they were combined with a final mouth rinse with clean water. The experiment was repeated seven times for each brand.

In a second experiment, repeated saliva samples were collected for individual analysis over the course of 20 minutes of chewing, in order to determine the rate at which microplastics were released from each piece of gum.

The team measured the number of microplastic particles in each sample by staining the particles red and counting them under a microscope, studying their chemical composition using a technique known as Fourier-transform infrared spectroscopy.

A limitation of this approach, the team notes, is that it was only able to identify those microplastic particles that were at least 20 micrometers wide—meaning that the microplastic counts are likely underestimated.

On average, the team found, one gram of gum released an average of 100 pieces of microplastic—although some individual pieces released as many as 600 per gram.

Given that large pieces of gum can weigh in at up to six grams, as many as 3,000 plastic particles could be released into one's mouth—and a regular chewing gum habit could significantly increase the total amount of microplastics consumed via food and drinks.

"Our initial hypothesis was that the synthetic gums would have a lot more microplastics because the base is a type of plastic," said paper co-author and UCLA biological engineer Lisa Lowe in a statement.

"Surprisingly, both synthetic and natural gums had similar amounts of microplastics released when we chewed them."

Both types of gum, the team added, also contained the same polymers—with the most abundant being polyolefins, a group of plastics that includes both polyethylene (used, for example, in plastic bags) and polypropylene (which is used in plastic packaging).

The researchers' analysis revealed that the lion's share of the microplastics were released from the gum in the first two minutes of chewing—thanks to the mechanical action, rather than the enzymatic properties of saliva—reaching 94 percent within eight minutes.

Given these findings, Lowe recommends that if people want to keep chewing gum, but reduce their exposure to microplastics, they chew one piece for longer rather than having multiple pieces.

Finally, the researchers note, their study highlights how discarded chewing gum can also present a plastic threat to the environment.

"The plastic released into saliva is a small fraction of the plastic that's in the gum," said Mohanty.

"So be mindful about the environment and don't just throw it outside or stick it to a gum wall."

The full findings of the study are being presented today at the American Chemical Society's spring meeting, which is being held in San Diego, California.

600-odd micrometer-sized pieces of plastic per piece of gum "is a very small amount indeed", commented chemist professor Oliver Jones of the Royal Melbourne Institute of Technology in Australia.

He added: "Since the lining of the intestine is fairly thick and well-regulated, any particles you swallowed would likely pass straight through you with no impact.

"In short, while microplastics are something we should definitely be keeping an eye on, I don't think you have to stop chewing gum just yet—although you should certainly dispose of it appropriately in a bin when you are finished with it," he concluded.

"The authors of this small pilot study readily admit in their press release that there is no cause for alarm. Gum is safe to enjoy as it has been for more than 100 years," the National Confectioners Association (NCA) told Newsweek.

"Food safety is the number one priority for U.S. confectionery companies, and our member companies use only FDA-permitted ingredients." ♦

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