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Chewing Gum and Microplastics: What a 2025 UCLA Pilot Study Found
· 3 min read
Gum base has always been some form of polymer — synthetic gum is explicitly made from petroleum-based rubber, while "natural" gum is marketed as plant-based chicle or similar tree resins. In 2025, a UCLA engineering team asked whether chewing either kind sheds microplastics into saliva, and presented an answer that surprised even the researchers.
The study
A team led by civil and environmental engineering professor Sanjay Mohanty, with graduate students Lisa Lowe and Jamie Leonard, tested 10 commercial gum brands — five synthetic, petroleum-based, and five marketed as natural or plant-based. Volunteers chewed seven pieces of each brand for four minutes, with researchers collecting saliva samples every 30 seconds to measure released particles; a follow-up experiment tracked release over a full 20 minutes (UCLA, presented at the American Chemical Society Spring 2025 meeting).
Important to flag up front: this is a pilot study presented at a conference, not yet a peer-reviewed journal publication at time of writing. Treat the numbers as an early, credible signal rather than a settled figure — the same caution we'd apply to any single unreplicated study.
What they found
- Average release: about 100 microplastic particles per gram of gum chewed, with some individual pieces shedding as many as 600 particles per gram.
- A typical 2–6 gram piece of gum could therefore release over 3,000 particles during chewing.
- 94% of particles came out in the first eight minutes of chewing — most of the release front-loads early rather than continuing steadily.
- Extrapolated to someone chewing 160–180 small sticks a year, the researchers estimated roughly 30,000 microplastic particles ingested annually from gum alone.
The surprising part
The team expected synthetic (petroleum-based) gum to shed more than "natural" plant-based gum. It didn't. Both types released similar amounts of microplastic, and matching polymer types — polyolefins, polyethylene terephthalates, polyacrylamides, and polystyrenes turned up in both. The likely explanation: "natural" gum bases are rarely pure plant resin in modern commercial products; many blend in synthetic polymers for texture and shelf stability, so the natural-vs-synthetic marketing distinction doesn't map cleanly onto what's actually shedding into your saliva.
What this doesn't tell us
Mohanty was explicit about the limits: "Scientists don't know if microplastics are unsafe to us or not. There are no human trials." This study measured release, the same way the McGill tea bag study measured release — it says nothing about whether swallowing these particles causes harm. As with everything else on this site's health effects guide, presence and dose are not the same as demonstrated harm, and gum's contribution here is small next to routes like bottled water or heated plastic containers.
Is this worth changing behavior over?
Put in context, 30,000 particles a year from gum is roughly in the same order of magnitude as one microwaved plastic container release event, and a small fraction of what a single plastic tea bag releases into one cup. It's a genuinely interesting finding — mostly because it debunks the "natural gum is the safe choice" assumption — but it doesn't rank near the top of a reasonable priority list. If you chew gum heavily and want to hedge anyway, there's no clearly lower-shedding category to switch to yet, since natural and synthetic performed about the same; moderation is the only lever this particular study points to.
This article describes research findings and general information, not personalized health advice.