A groundbreaking UCLA study reveals that chewing gum releases significant amounts of microplastics into saliva. Researchers aim to raise awareness of this overlooked source of microplastic ingestion and its potential health impacts.
In a discovery that could change the way we think about chewing gum, researchers have found that each piece can release up to thousands of microplastic particles into saliva, which are potentially ingested. This groundbreaking pilot study will be presented at the American Chemical Society (ACS) Spring 2025 meeting, highlighting a new, previously unconsidered source of microplastic exposure.
“Our goal is not to alarm anybody,” Sanjay Mohanty, the study’s principal investigator and an engineering professor at the University of California, Los Angeles, said in a news release. “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 and his graduate student Lisa Lowe conducted extensive testing using both natural and synthetic gums. Chewing gum is primarily made from a rubbery base, sweeteners, flavorings and other ingredients. While natural gums use plant-based polymers like chicle, synthetic gums employ 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,” added Lowe, who began the project as an undergraduate intern at UCLA.
The experiment involved one person chewing seven pieces from five brands of both synthetic and natural gums, collecting saliva samples at multiple intervals. This method minimized variance in chewing patterns and saliva production, allowing for more controlled results.
The researchers discovered that both types of gum released average of 100 microplastics per gram. Some samples, however, released as many as 600 microplastics per gram. This translates to a significant number of particles potentially ingested annually by habitual gum chewers – potentially around 30,000 microplastics a year.
“Surprisingly, both synthetic and natural gums had similar amounts of microplastics released when we chewed them,” Lowe added.
The most abundant polymers found were polyolefins, including polyethylene and polypropylene, common in many plastic products.
The majority of microplastic release occurred within the first two minutes of chewing. After eight minutes, 94% of the plastics were detached. The process is attributed to the abrasive action of chewing rather than enzymatic breakdown by saliva.
To minimize exposure, Lowe suggests chewing a single piece longer rather than frequently switching pieces.
However, it is worth noting that the study could only identify microplastics 20 micrometers or larger due to technological limitations, implying that even finer particles might be present but undetected.
“The plastic released into saliva is a small fraction of the plastic that’s in the gum,” concluded Mohanty. “So, be mindful about the environment and don’t just throw it outside or stick it to a gum wall.”
Improper disposal can contribute further to environmental plastic pollution.
Funded by UCLA and the University of Hawaii Maximizing Access to Research Careers program backed by the National Institutes of Health, the study represents a crucial step in understanding less obvious sources of microplastic ingestion.
Source: American Chemical Society