What You Think Is a Simple Chewing Gum Actually Releases Up to 600 Microplastics Per Gram Into Your Saliva

A chewing gum, chewed for just a few minutes, can release up to 600 plastic fragments per gram directly into saliva. This is the conclusion of a pilot study conducted by engineers at the University of California, Los Angeles (UCLA), presented at the American Chemical Society’s Spring meeting in San Diego. Lisa Lowe measured an average of 100 microplastics released per gram of gum, with some individual gums releasing as many as 600 per gram. A standard piece of chewing gum weighs between 2 and 6 grams, which means a large piece could discharge up to 3,000 plastic particles.

A Simple Experiment, Results That Prompt Reflection

The protocol set up by the team led by Sanjay Mohanty, a professor of civil and environmental engineering at UCLA’s Samueli School of Engineering, bordered on dentist’s routine. In the laboratory, one volunteer chewed seven pieces of each brand for four minutes, with researchers collecting saliva samples every 30 seconds. A second experiment pushed the exercise further: samples were collected repeatedly over a 20-minute period to measure the rate at which microplastics were released from each gum piece.

The mechanism at play is not chemical. Most microplastics were released within the first two minutes of chewing due to abrasive action that physically detaches plastic fragments from the whole piece, rather than an effect of salivary enzymes. It is not oral digestion that breaks down the gum; it is simply the rubbing of teeth. This finding is confirmed later in the study: 94% of particles were released during the first eight minutes of chewing. The takeaway for gum enthusiasts may be surprising: to reduce the amount of microplastics ingested, it is better to chew a single piece for longer, rather than constantly switch to new pieces.

Natural or Synthetic, Same Verdict

Here is where the study challenges common beliefs. Gums marketed as natural, based on chicle or other plant resins, are sold as a healthier option. The researchers started with this assumption. “Our starting hypothesis was that synthetic gums would contain far more microplastics because their base is a type of plastic,” explains Lisa Lowe. The result contradicted this intuition: natural and synthetic gums released similar levels of microplastics.

The explanation lies in the actual composition of the products tested. Both categories of gums contained the same polymers: polyolefins, polyethylene terephthalate, polyacryl amide, and polystyrene, with polyolefins (a group of plastics including polyethylene and polypropylene) being the most abundant in both types of gum. The problem thus wouldn’t originate from the tree-based chicle itself. A hypothesis advanced by Lisa Lowe points instead to the manufacturing steps: microplastics could be introduced during gum production or packaging, rather than by the plant-based starting material.

Do We Really Need to Worry?

When scaled to a yearly basis, the chewing habit takes on another dimension. If an average person chews 160 to 180 small gum pieces per year, researchers estimate that this could lead to the ingestion of about 30,000 microplastics. A figure that seems dizzying until compared with the rest of our daily diet. Previous research estimates that a person consumes between 39,000 and 52,000 microplastic particles per year through water, tea bags, seafood, or olive oil. Chewing gum thus adds a non-negligible source to an already substantial total, without being the main entry point for plastic into the body.

The lead researcher remains cautious about how to interpret these numbers. “Our aim is not to alarm anyone,” said Sanjay Mohanty in a press release. “Scientists do not know whether microplastics are dangerous to us or not. There are no human trials.” This view is echoed outside the UCLA team: chemist Oliver Jones of the Royal Melbourne Institute of Technology even downplayed the magnitude of the phenomenon, noting that a total of around 600 microplastics per gum piece remains a modest amount.

The study also has a significant technical limitation that invites careful interpretation of the figures. It was limited to identifying microplastics at least 20 micrometers in diameter due to the instruments and methods used, and it is likely that smaller particles were not detected in saliva. The real count could be much higher than 600 per gram if nanoplastics were included—undetectable with current tools. The work, presented as a preprint, has not yet progressed to peer-reviewed publication, which invites readers to view these results as a starting point rather than a definitive conclusion.

One final detail, almost anecdotal yet revealing: the same researchers note that gum discarded on a sidewalk or stuck under a table releases only a tiny fraction of its total plastic into saliva. “The plastic released into saliva is only a small fraction of the plastic contained in the gum,” concludes Mohanty, who urges environmental awareness and not simply discarding it outdoors or sticking it on a chewing-gum-stained wall. The real reservoir of microplastics remains largely trapped in the piece we spit out, a waste that will continue to degrade slowly long after leaving our mouth.

Sources: enerzine.com | samueli.ucla.edu