New research suggests chewing gum could release thousands of microplastics into our mouths
News Bethan Finighan Science and Innovation Writer 18:24, 25 Mar 2025
They're in the water we drink, the food we eat, and the air we breathe – microplastics are everywhere, and new research has revealed yet another way they could be making their way into our bodies.
Chewing a single piece of gum could release hundreds to thousands of microplastics into your mouth, a new study has warned.
Article continues below
The study estimated that humans consume tens of thousands of microplastics, tiny plastic particles less than five millimetres long, each year.
“Our goal is not to alarm anybody,” says Sanjay Mohanty, the study's lead investigator and an engineering professor at the University of California, Los Angeles (UCLA). “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.”
The findings, which have not yet been published or peer reviewed, were presented at the spring meeting of the American Chemical Society. The team tested five brands of commercially-available gum, both synthetic and natural.
“Our initial hypothesis was that the synthetic gums would have a lot more microplastics because the base is a type of plastic,” says Lowe, who started the project as an undergraduate at UCLA and the presenter of this research.
Chewing gum is made from a rubbery base, sweetener, flavorings, and other ingredients, whereas natural gum is made using a plant-based chemical compound.
“Surprisingly, both synthetic and natural gums had similar amounts of microplastics released when we chewed them,” says Lowe.
In the study, each piece of gum was chewed for four minutes and saliva samples were collected throughout. Microplastics in the saliva were counted under a microscope or analysed using a technique called spectroscopy.
They found that most gums released an average of 100 microplastics per gram of gum, however some released six times as much as this. Since a typical piece of gum weighs between two and six grams, a large piece of gum could release up to 3,000 plastic particles, the researchers warn.
What's more, they say a person who chews between 160 and 180 small pieces of gum a year could swallow around 30,000 microplastics.
However, one expert believes an issue with the experiment could explain the surprising findings that natural gums release just as many microplastics. “A potential issue is that the authors used a dye called Nile Red to stain the microplastics to make them easier to see," said Prof Oliver Jones, Professor of Chemistry at RMIT University.
"This is a common approach, but the method has potential issues in that Nile Red can stain a wide variety of natural and synthetic particles, and some biological materials can autofluorescence, which makes them look like dyed plastic when they aren’t," he explained.
There is also limited evidence to suggest that microplastics pose a risk to human health. However, some studies in animals and human cells suggest microplastics could cause harm. One recent study found that microplastics act like blood clots in the brains of mice, negatively impacting their mobility.
Article continues below
Another revealed that the plastic commonly found in plastic water bottles could carry harmful toxins into the human body, harming kidney cells.
Despite the uncertainty in the effects of microplastics on our health, it is widely known that plastic pollution is a global problem.
“The plastic released into saliva is a small fraction of the plastic that’s in the gum,” concludes Mohanty. “So, be mindful about the environment and don’t just throw it outside or stick it to a gum wall.” If used gum isn’t properly thrown away, it’s another source of plastic pollution to the environment, too.
