Microplastics are turning up in places researchers never expected: deep-sea sediments, Arctic ice, and human blood. Now, a UCLA pilot study has added chewing gum microplastics to that list and the source is as close as the stick of gum in your pocket.
Presented at the American Chemical Society’s Spring 2025 meeting, the research identifies chewing gum as a previously overlooked but meaningful source of daily microplastic ingestion. The implications are particularly significant for habitual gum chewers.
What the researchers actually tested
The UCLA team examined a range of commercially available gum products under realistic chewing conditions, tracking how many plastic particles migrated into simulated saliva. Their selection included both traditional synthetic gums formulated with polymer bases such as polyethylene, polyvinyl acetate, and polystyrene and brands explicitly marketed as “natural,” using chicle or other plant-derived bases.
The mechanism driving particle release turned out to be straightforward: mechanical abrasion. As teeth repeatedly compress and shear the gum base, combined with the chemical action of saliva, microscopic fragments are continuously dislodged and enter the oral cavity.
“A single piece of gum can shed anywhere from hundreds to more than 3,000 microplastic fragments over just 10 to 30 minutes.”
The “natural” gum myth
Perhaps the most counterintuitive finding from the study was the performance of plant-based alternatives. Despite being marketed with health and environmental credentials, “natural” gums performed no better than their synthetic rivals and in several tested cases, actually released higher particle counts. This suggests the problem is not simply about petroleum-derived polymers, but about the mechanical properties of the gum base itself.
All particle sizes measured fell within the definition of microplastics fragments smaller than 5 millimetres making them easily ingestible during normal chewing.
Once swallowed, they don’t break down
The downstream fate of these particles compounds the concern. Once ingested, microplastic fragments are chemically resistant to digestive enzymes and pass through the gastrointestinal tract largely intact, accumulating as persistent pollutants. While direct causal links to disease in humans remain under investigation, emerging research has raised questions about potential associations with chronic low-grade inflammation, disruption of gut microbiome composition, and the leaching of plasticiser chemicals.
Lead researcher Professor Sanjay Mohanty was careful to frame the findings within a broader picture of daily plastic exposure rather than as an isolated alarm — but noted that for regular gum chewers, this is a non-trivial contribution to overall intake.
If you chew gum regularly, the data suggests that chewing one piece for a longer session is meaningfully better than frequently swapping in a fresh piece. Particle release peaks in the first few minutes and then decreases — so most of your plastic exposure comes right at the start.
The study also carries a regulatory message. Unlike food products or food packaging, the polymer composition of chewing gum bases is rarely disclosed to consumers. Professor Mohanty’s team argues this needs to change particularly as microplastics continue to appear in unexpected corners of daily life, from bottled water to seafood to, now, the contents of a foil wrapper.
As researchers build a more complete picture of cumulative plastic exposure, chewing gum joins a growing list of ordinary consumer products quietly adding to the burden — one that most people would not think twice about.
STUDY REFERENCE
Lowe, L., Leonard, J., & Mohanty, S. K. (2025). Ingestion of microplastics during chewing gum consumption. Journal of Hazardous Materials Letters, 6, 100164. DOI: 10.1016/j.hazl.2025.100164
