Chewing Gum Can Shed Microplastics Into Saliva: American Chemical Society

Microplastic exposure may increase risk of some cancers and reproductive issues.

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Chewing a single piece of gum releases hundreds or thousands of microplastics into the saliva, with the average gum-chewer at risk of ingesting 30,000 microplastics in a year, according to a new pilot study.

Researchers of the study “wanted to identify how many microplastics a person could potentially ingest from chewing natural and synthetic gums,” the American Chemical Society said in a March 25 statement. While natural products use plant-based polymers to achieve a chewy texture, other gums “use synthetic rubber bases from petroleum-based polymers.”

“Our goal is not to alarm anybody,” Sanjay Mohanty, the project’s principal investigator and an engineering professor at the University of California, Los Angeles, said. “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.”

The study tested five brands of synthetic gum and five natural gums. A person was tasked with chewing the gum for four minutes in one experiment, and 20 minutes in another, with saliva samples periodically collected to assess microplastic content. Pilot studies are typically small-scale tests done to refine variables involved in the research before a larger full-scale investigation.

Only one individual was involved to reduce the human factor of varied chewing patterns and saliva.

The study found that “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,” said the statement.

“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.”

Lisa Lowe, one of the researchers, said there wasn’t any difference between natural and synthetic gums in terms of the amount of microplastics released when chewing, and the particles contained the same polymers.

Sanjay Mohanty, the project’s principal investigator, said the study was limited to analyzing microplastics that were 20 micrometers in width and above. As such, it is likely that smaller-sized microplastics were not detected in the saliva.

“The plastic released into saliva is a small fraction of the plastic that’s in the gum,” he said.

Researchers presented the study during the March 23–27 spring meeting of the American Chemical Society.

The study was funded by the University of California–Los Angeles (UCLA), and the University of Hawaii Maximizing Access to Research Careers program, an initiative funded by the National Institutes of Health and the California Protection Council. Mohanty is an engineering professor at UCLA, and Lowe is a graduate student in his lab.

Microplastic Harms

Microplastics pose a significant health risk for humans, according to research. A recent review of 3,000 studies found that microplastics floating in the air could be driving up rates of colon and lung cancer.

These particles have been “shown to accumulate in organs and lead to biological changes, including oxidative stress and inflammation in human cell lines,” the authors wrote in the review.

Oxidative stress caused by microplastics can overwhelm the body’s defenses, eventually damaging the DNA. They may interfere with a body’s hormone function and weaken the immune system’s ability to combat cancer.

Microplastic exposure has been associated with reproductive issues, metabolic disorders, and poor respiratory outcomes.

Over the past years, microplastics have been found in various organs of the human body. A September study discovered these plastics in the brain for the first time ever.

Microplastics were found in the olfactory bulb region of the brain which is responsible for the sense of smell and is located just above the nose. They have also been identified in the testicles, bloodstream, liver, gut, and lungs.

A February 2024 study discovered microplastics in the human placenta, which is an organ that develops in the uterus during pregnancy, providing oxygen and nutrients to the baby.

Scientists are looking at various ways to deal with the issue of microplastic contamination. A research letter published last year suggested that the amount of microplastics in tap water could be reduced by up to 90 percent by just boiling the water for five minutes.

“This simple boiling-water strategy can ‘decontaminate’ [nano- and microplastics] from household tap water and has the potential for harmlessly alleviating human intake of [nano- and microplastics] through water consumption,” the researchers wrote.