Chewing Gum Releases Thousands of Microplastics Into Our Saliva, Researchers Find

In just the last couple of years, scientists have found microplastics in disturbing placesfrom beneath Arctic ice to human blood, testiclesand even brains. In fact, plastic is so widespread that it has triggered a new geological epoch. Now, researchers have added chewing gum to the growing list of products that expose humans to microplastics.

A team of researchers has revealed that chewing a single stick of gum can release hundreds to thousands of microplastics into our saliva—meaning it most likely gets ingested. The researchers presented the pilot study at the spring meeting of the American Chemical Society (ACS) on Tuesday.

“Our goal is not to alarm anybody,” Sanjay Mohanty, an engineer at the University of California, Los Angeles, who participated in the research, said in an ACS 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.” While more research is needed, it’s worth noting that previous studies have already linked microplastics to health complications.

Scientists have previously estimated that people ingest at least 50,000 microplastics a year. Given this evaluation, Mohanty and his colleagues decided to investigate the amount of microplastics that’s being released by chewing gum. They tested 10 commercially available brands: five synthetic gums and five natural gums. To avoid having to consider different salivas and chewing patterns, the team had a single participant chew seven pieces of each brand.

“Our initial hypothesis was that the synthetic gums would have a lot more microplastics because the base is a type of plastic,” explained Lisa Lowe, a graduate student in Mohanty’s lab who participated in the research.

While the participant chewed each piece of gum, the researchers took saliva samples at various time intervals. They then measured the amount of microplastics in the samples, either by staining the particles red and counting them with a microscope, or via a technique called Fourier-transform infrared spectroscopy that can identify components within a mixture.

Ultimately, the team found that chewing gum released an average of 100 microplastics per gram of gum, and that 94% of the total microplastics documented in the study were released during the first eight minutes of chewing. The release of microplastics is the result of the abrasive mechanics of chewing, which detaches the particles from the gum, rather than from the saliva breaking them down.

“Surprisingly, both synthetic and natural gums had similar amounts of microplastics released when we chewed them,” said Lowe, and contained the same polymers (plastics are a type of polymer).

Some sticks of gum released as many as 600 microplastics per gram. Based on an estimate of 160 to 180 sticks per year—though some sources put that number closer to 300—a person could be swallowing around 30,000 microplastics annually from gum alone. Since the researchers’ instruments limited them to detecting microplastics 20 micrometers or larger, smaller particles might make that number even higher.

Furthermore, “the plastic released into saliva is a small fraction of the plastic that’s in the gum,” Mohanty pointed out, meaning that once you’re done with it, it can still contribute to environmental plastic pollution. “So, be mindful about the environment and don’t just throw it outside or stick it to a gum wall.”