Chewing gum is a daily companion for millions of people around the world. We chew it for fresh breath, to concentrate, to fight nervousness or simply out of habit. Yet, behind that common gesture could hide a disturbing phenomenon: the release of hundreds of microplastics directly into our saliva.
These are the results of a study conducted at theUniversity of California, Los Angeles (UCLA), who analyzed both synthetic and natural rubbers. And the most surprising discovery? Both types release similar amounts of plastic fragments. Every year, humans are exposed to tens of thousands of microplastics through food, drinks, packaging and manufacturing processes, and now it appears that chewing gum is also a significant contributor to this burden.
A time bomb in your mouth
The experiment conducted by UCLA researchers was revealing: They asked volunteers to chew a single piece of gum for 4 minutes, collecting saliva samples every 30 seconds. In a separate test, they monitored the release of microplastics over a 20-minute period.
The results? Each gram of gum releases on average around 100 microplastics, with some pieces releasing up to 600. Considering that a chewing gum weighs between 2 and 6 grams, this means that a single piece could release up to 3.000 plastic particles directly into your mouth.
What strikes me most is that these microplastics are released mainly in the first two minutes of chewing, due to the abrasive action and not due to enzymatic degradation. Within eight minutes, 94% of microplastics have already been released into saliva. Perhaps it is better to chew the same piece longer than to change it often.
The surprise of “natural” gums
The researchers’ initial hypothesis was logical: synthetic rubber, with its base of petroleum-derived polymers, should have released many more microplastics than “natural” alternatives based on chicle or other plant-based polymers. But the reality was quite different.
Surprisingly, both synthetic and natural gums released similar amounts of microplastics when we chewed them.
He has declared Lisa Lowe, one of the researchers who initiated this study. Both types release the same types of microplastic polymers, including polyolefins, polyethylene terephthalates, polyacrylamides e polystyrene. Polyolefins (which include polyethylene and polypropylene) were found to be the most prevalent.
Chewing gum, the cumulative impact on the body
Researchers estimate that chewing 160-180 pieces of gum a year (an average of about one piece every two days) approximately 30.000 microplastics could be ingested, which would be added to the already considerable quantity which we obtain from other sources.
The study only measured microplastics 20 micrometers or larger due to technical limitations. The researchers suspect that even smaller plastic particles (nanoplastics) may have escaped their analysis and call for further research to also assess their release from chewing gum.
Sanjay Mohanty, principal investigator of the project and professor of engineering atUCLA, he is keen to point out in a statement:
Our goal is not to alarm anyone. Scientists don’t know whether microplastics are dangerous for us or not. There are no human trials. But we know that we are exposed to them in our daily lives, and that’s what we wanted to look at.
In addition to the health impact, the researchers also highlight the environmental impact. “The plastic released in saliva is only a small fraction of the plastic present in the gum. So, be careful of the environment and do not throw it outside or attach it to a 'gum wall',” he concluded. Mohanty in the press release.
The results were presented at theAmerican Chemical Society's Spring 2025 meeting.
