Stop munching on that plastic.

The U.S. National Institute of Health estimates that over 350 billion pieces of chewing gum are consumed globally every year, making gum one of the most widely enjoyed edibles on Earth. But according to a new study, chewing just one piece may release thousands of microplastics into your saliva.

Until now, studies on microplastics have mostly focused on fruits, packaged drinking water, seafood, plastic bags, and vegetables. However, microplastics in chewing gum have rarely been studied. Most people don’t realize that synthetic chewing gum contains around 2.5% plastic — making it the only widely consumed food product literally made of plastic.

Therefore, it is quite important to estimate total microplastic exposure from chewing gum in the human body and identify any possible negative effects.

“Our initial hypothesis was that the synthetic gums would have a lot more microplastics because the base is a type of plastic. Surprisingly, both synthetic and natural gums had similar amounts of microplastics released when we chewed them,” Lisa Lowe, one of the study authors and a graduate student at the University of California, Los Angeles (UCLA), said.

Plastic ain’t fantastic

To understand how much plastic we might be ingesting from gum, researchers examined ten popular gum brands — half synthetic, half made from natural ingredients. The study authors conducted two tests. During the first one, a subject chewed gum for four minutes and released saliva every 30 seconds. Then, they rinsed their mouth and tried other gum. 

In the next experiment, the researchers extracted saliva samples for more than 20 minutes to monitor the rate at which the gums released microplastics. The samples were then observed under a microscope, with microplastic particles stained red for identification. 

The test and analysis revealed that chewing gum released 100 to 600 microplastic particles per gram. Since regular gum can weigh up to six grams, chewing one piece will fill your saliva with 3,000 microplastics. Data suggests that in a year, on average, a person consumes between 150 and 180 gums, which means they are ingesting 30,000 microplastic particles annually.

“Our goal is not to alarm anybody. 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,” Sanjay Mohanty, one of the study authors and a professor at UCLA, said.

The analysis revealed no noticeable difference in the amount of microplastics released by synthetic and natural gum. When asked how this was even possible, the researchers said they were also surprised. They are not sure about organic or other food products but most of them are packaged in plastics wrap or containers, so maybe that could be a source of microplastics. Or maybe the gum wasn’t quite as natural after all.

Microplastics mix fast in saliva

The rate at which chewing gum releases microplastics in saliva is quite astonishing. The test suggests that within eight minutes of chewing a gum stick, 94% of microplastic particles are released into saliva, with most being shed in the first two minutes.

This also suggests that if someone chews a single piece of gum for longer, they are not introducing new plastic particles into their saliva. However, people who have the habit of frequently replacing their gum with a fresh piece restart the cycle and expose themselves to more microplastics each time.

Another important point to keep in mind is that “the plastic released into saliva is a small fraction of the plastic that’s in the gum. So, be mindful of 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,” Mohanty said. 

Previous research suggests that microplastics in edible products can lead to a series of health issues ranging from abdominal pain to a disturbed gut microbiome. However, the authors of the current study refused to comment on any potential negative effects of ingesting the microplastics from chewing gum. 

“Our study is about finding microplastics in a food product, but it did not provide any data about health effects. We are not aware of direct harmful health effects of microplastics (human toxicity). It would be very speculative for us to comment on that,” Mohanty told ZME Science.

Hopefully, further research will shed more light on this matter.

The study is presented at ACS Spring 2025.