Chewing Gum Microplastics May Pose Hidden Health Risks, Study Finds

A new study has revealed that chewing gum microplastics could pose potential health risks, as each piece may release hundreds to thousands of microplastic particles into a person’s saliva. People can ingest these particles, raising concerns about their long-term impact on human health. Researchers presented the findings at the American Chemical Society’s Spring 2025 meeting, held from March 23–27.

Investigating Plastic Exposure Through Chewing Gum

“Our goal is not to alarm anyone,” says Sanjay Mohanty, the project’s lead investigator and UCLA engineering professor.

“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,” Mohanty

Animal studies and studies with human cells show that microplastics could cause harm, so while we wait for more definitive answers from the scientific community, individuals can take steps to reduce their exposure to microplastics, the researchers said.

Scientists estimate that humans consume tens of thousands of microplastics (between 1 micrometer- and 5 millimeters-wide) every year through foods, drinks, plastic packaging, coatings, and production or manufacturing processes. Yet, chewing gum as a potential source of microplastics hasn’t been widely studied, despite the candy’s worldwide popularity.

Examining Microplastic Release in Different Gums

Mohanty and a graduate student in his lab, Lisa Lowe, wanted to identify how many microplastics a person could potentially ingest from chewing natural and synthetic gums.

Chewing gum is made from a rubbery base, sweetener, flavorings, and other ingredients. Natural gum products use a plant-based polymer, such as chicle or other tree sap, to achieve the right chewiness, while other products use synthetic rubber bases from petroleum-based polymers.

“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 intern at UCLA and the presenter of this research.

The researchers tested five brands of synthetic gum and five brands of natural gum, all of which are commercially available. Mohanty says they wanted to reduce the human factor of varied chewing patterns and saliva, so they had seven pieces from each brand all chewed by one person.

In the lab, a person chewed a piece of gum for four minutes and provided saliva samples every 30 seconds. Afterward, they rinsed their mouth with clean water. Researchers combined all the samples into one. In another experiment, they collected saliva at regular intervals over 20 minutes to measure how quickly each piece of gum released microplastics.

Then, the researchers measured the number of microplastics present in each saliva sample. Researchers either stained the plastic particles red and counted them under a microscope or analyzed them using Fourier-transform infrared spectroscopy, which also revealed their polymer composition

Lowe measured an average of 100 microplastics released per gram of gum, though some individual gum pieces released as many as 600 microplastics per gram. A typical piece of gum weighs between 2 and 6 grams, meaning a large piece of gum could release up to 3,000 plastic particles.

If the average person chews 160 to 180 small sticks of gum per year, the researchers estimated that could result in the ingestion of around 30,000 microplastics. If the average person consumes tens of thousands of microplastics per year, gum chewing could greatly increase the ingested amount.

Natural vs. Synthetic Gums: Similar Microplastic Content

“Surprisingly, both synthetic and natural gums had similar amounts of microplastics released when we chewed them,” says Lowe. And they also contained the same polymers: polyolefins, polyethylene terephthalates, polyacrylamides and polystyrenes. The most abundant polymers for both types of gum were polyolefins, a group of plastics that includes polyethylene and polypropylene.

Most of the microplastics detached from gum within the first 2 minutes of chewing. But Mohanty says they weren’t released because of enzymes in saliva breaking them down. Rather, the act of chewing is abrasive enough to make pieces flake off. After 8 minutes of chewing, the tests showed that people had released 94% of the plastic particles collected.

Reducing Exposure to Microplastics: Tips for Gum Chewers

Therefore, Lowe suggests that if people want to reduce their potential exposure to microplastics from gum, they chew one piece longer instead of popping in a new one.

The study identified only microplastics 20 micrometers wide or larger due to the limitations of the instruments and techniques used. Mohanty says researchers likely missed smaller plastic particles and need more research on chewing gum releasing nano-sized plastics.

“The plastic released into saliva is a small fraction of the plastic that’s in the gum. So, be mindful about the environment and don’t just throw it outside or stick it to a gum wall. If people don’t dispose of used gum properly, it adds to plastic pollution in the environment,” said Mohanty.