- A new study found that chewing gum releases hundreds to thousands of microplastics for every gram of gum.
- Both synthetic and natural gums were found to contain microplastics.
- While the long-term effects of exposure to microplastics are not well understood, emerging evidence has suggested several potential health harms.
Chewing gum can release hundreds to thousands of microplastics into the saliva that may be ingested.
Research presented this week at the spring meeting of the American Chemical Society in San Diego, CA, found that, on average, 100 microplastics were released per gram of chewing gum. The research has not yet been published in a peer-reviewed journal.
“Our goal is not to alarm anybody,” Sanjay Mohanty, PhD, the project’s principal investigator and an engineering professor at the University of California, Los Angeles (UCLA), said in a press statement.
“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.”
Past research estimates that an individual consumes between 39,000 and 52,000 particles of microplastics annually.
Microplastics are everywhere, and humans may be exposed to them through drinks, foods, plastic packaging, chopping boards, sponges, coatings on products, and the manufacturing process of items.
Chewing gum is one area that hasn’t been widely researched.
“My lab has done work mainly on microplastic transport in water and soil and their fate in soil. We learned different ways one can be exposed to microplastics: ingestion and inhalation,” Mohanty told Healthline.
“Most of the ingestion studies related to food are [about the] contamination of food with microplastic from plastic containers (e.g., plastic water bottles, plastic tea bags), but chewing gum is the only food that is made up of plastics. Yet, most don’t know. We wanted to measure microplastics in chewing gum. This is important to estimate total microplastic exposure into the human body and any possible negative effects,” Mohanty continued.
Chewing gum and microplastics exposure
Chewing gum is made with flavoring, sweetener, a rubber base, and other ingredients.
In chewing gums that are “natural,” a plant-based polymer, like tree sap, gives the gum chewiness. Synthetic rubber bases from a petroleum-based polymer (plastic) are used for synthetic gums.
The researchers examined five types of synthetic gum along with five types of natural gum that are commercially available.
As part of the experiment, one person chewed seven pieces of gum from each brand to account for varied chewing patterns and saliva.
The person chewed the gum for four minutes and produced a saliva sample every 30 seconds. They then rinsed their mouth with clean water. The saliva samples were then combined into one sample.
In a different experiment, saliva samples were collected every 20 minutes.
The researchers then measured the amount of microplastics present in the saliva samples.
The researchers initially suspected that synthetic forms of chewing gum would contain more microplastics but were surprised to find natural chewing gums also contained a similar amount of microplastics.
“We were not surprised to find microplastics in chewing gum but we are surprised to find them equal amount in both synthetic and organic gum. We assumed organic one should have less than that of synthetic… We are perplexed by the source of microplastics in them (natural gums),” Mohanty said.
Microplastics found in synthetic and natural gums
The researchers found an average of 100 microplastics were released for every gram of gum.
Some pieces of gum produce up to 600 microplastics per gram. For context, the researchers note that a single piece of gum typically weighs 2–6 grams.
The researchers also found that both the synthetic and natural gums contained the same kind of polymers, the highest amount were of polyolefins, a type of plastic that includes polyethylene and polypropylene.
Tracey Woodruff, PhD, a professor of obstetrics and gynecology at UCSF who has studied the health impacts of microplastics, said the fact chewing gum contains microplastics isn’t entirely surprising. Woodruff wasn’t involved in the study.
“Nothing surprises me about how many places plastic is anymore, but it is sad and surprising in the fact that these things that are in our food or putting in our mouth, sometimes, for a long time, could be releasing microplastics,” she told Healthline.
“We already know we’re exposed to lots of different micro plastics… because they’ve been measured in every part of the body… But the problem is, is that the gum that you’re chewing is adding on to all the other microplastic exposure you’re already getting.”
Health impacts of microplastics
The health impacts of microplastics on humans are still the subject of ongoing research.
One 2024 review found that microplastics were suspected to harm human respiratory health, digestive health and reproductive health and were also possibly associated with colon and lung cancer.
Dana Hunnes, PhD, a senior clinical dietitian at UCLA Health, told Healthline that despite knowing that microplastics are widespread, the findings of the study are still shocking. Hunnes wasn’t involved in the study.
“I honestly never would have thought to even think about chewing gum as a source of microplastics! Yes, I am very surprised with this study, and not pleasantly so. When chewing gum, most people tend to swallow their saliva, so if chewing gum is releasing microplastics into saliva that people are swallowing, that’s not great,” she told Healthline.
Should you stop chewing gum?
Hunnes noted that some people may prefer to reduce their use of chewing gum or stop chewing gum altogether.
“This article indicated that both natural and manufactured chewing gums contained similar amounts of microplastics, so, in that case, it likely doesn’t much matter which they’re chewing. It might be best to stop or at least decrease the frequency. Especially for children [with] developing and more-susceptible brains to these chemicals causing damage,” Hunnes said.
Woodruff said chewing gum is a personal choice, but her own preference is to refrain from chewing gum.
“The more you chew, the more micro plastics you’re going to expose yourself to. And the other component of this is you’re adding plastics to already existing, ongoing plastic exposure. So my own preference would be to not chew chewing gum,” she said.
“If people are interested in lowering their exposures to microplastics, which we know are linked to certain types of health effects, not consuming chewing gum would be an option to avoid microplastic exposures.”
