Microplastics in Chewing Gum: What's Actually in Gum Base
People search for microplastics in chewing gum because they have started reading ingredient labels and found a vague line called "gum base." This guide explains what that phrase can legally include, what new research says about microparticles in saliva, and why we chose a single tree resin from Chios for Gum of Gods.
We will also be straight with you about what the science does not yet know.
At a glance
| Gum | What the chew is made of |
|---|---|
| Regular gum | Synthetic gum base (plastics) |
| Chicle gum | Tree latex plus sweeteners |
| Chios mastic | Chios mastic resin |
What is in regular chewing gum base?
Regular gum base contains plastics. US rules let chewing gum base include synthetic polymers such as polyvinyl acetate, polyethylene, polyisobutylene, butyl rubber and butadiene-styrene rubber, alongside waxes and softeners. Labels usually just say "gum base," so shoppers rarely see which of these polymers are actually inside the piece they chew.
The legal list lives in the US Code of Federal Regulations, 21 CFR 172.615, "Chewing gum base." It splits allowed masticatory substances into natural latices of plant origin (like chicle and natural rubber) and synthetic ones. The synthetic column includes:
- Polyvinyl acetate (minimum molecular weight 2,000)
- Polyethylene (molecular weight 2,000 to 21,000)
- Polyisobutylene
- Isobutylene-isoprene copolymer, also called butyl rubber
- Butadiene-styrene rubber
These are the same families of polymers used in glues, plastic films and tire rubber. They are approved as food additives, and the regulation limits them to the amounts needed for the intended effect.
But "approved" is not the same as "what you would choose if you knew." The American Chemical Society puts it plainly: "The base for conventional chewing gum contains food-grade plastic polymers."
Why does gum base use plastic polymers?
Plastic polymers give modern gum its long, stretchy, flavor-holding chew at low cost and huge scale. Synthetic bases are consistent batch to batch and cheap to produce. That is why most mainstream gum switched away from natural tree saps during the twentieth century, and why "gum base" became a catch-all label.
What did the 2025 ACS chewing gum study find?
A 2025 pilot study presented at the American Chemical Society found chewing gum can release microplastics.
The UCLA team behind it tested five synthetic and five natural gum brands, with one person chewing seven pieces of each, and later published the results in the Journal of Hazardous Materials Letters (2025). The study also found natural and synthetic gums released similar amounts. Gum of Gods was not part of this study.
The researchers suggested chewing one piece longer instead of swapping in new pieces, because most particles came off early in the chew.
It was a pilot with a single chewer and ten brands. Researchers are still studying where the particles in natural gum come from.
So what is Chios mastic gum made of?
Chios mastic is a single natural tree resin. It is the hardened sap of the mastic tree, Pistacia lentiscus, hand harvested on the Greek island of Chios. There is no synthetic gum base added to chew. The resin itself is the chew, which is why it starts firm and softens as you work it.
That is a different starting point from regular gum. With regular gum, the chewy part is often a blend of synthetic polymers that the label does not break out. With mastic, the chewy part is the resin.
We make no claim about microplastics in saliva for any gum, ours included. What we can say is simple: no plastic gum base. Regular gum base contains plastics. Our mastic packs are tree resin.
You can learn more about the resin itself in What Is Mastic Gum? and how to spot imitations in Real vs Fake Mastic Gum.
How is mastic different from "natural" chicle gums?
Chicle gums use a tree latex from Central America, often blended with other ingredients, sweeteners and flavors. Chios mastic is a resin from a different tree on one Greek island, chewed with no added base. Both avoid a synthetic base, but they differ in texture, taste and history.
Chicle is soft from the first chew and behaves a lot like the gum most people grew up with. Mastic is firmer, has a piney, slightly cedar taste and has been chewed around the Mediterranean for centuries. If you want a side by side breakdown, read Mastic Gum vs Regular Gum.
How can you lower your exposure if you chew gum?
Keep one piece in your mouth longer instead of swapping pieces often. In the UCLA pilot, 94% of particles came out in the first 8 minutes of chewing, so frequent fresh pieces may add more early shedding.
Practical steps:
- Read the label. If it says "gum base" with no detail, assume it can include the synthetic polymers listed in 21 CFR 172.615.
- Chew one piece longer. This follows the researchers' own suggestion and the 8-minute finding.
- Bin it, do not drop it. Spent gum is litter, and synthetic bases do not break down like food.
- Pick a base you understand. A single ingredient resin is easier to reason about than an unnamed blend.
Is mastic gum a good daily chew?
For most people, yes. Chios mastic has been chewed for centuries, and it is firm enough that many people chew it for a long session instead of reaching for piece after piece. Start with one or two pieces and see how your jaw feels, especially if you have jaw joint (TMJ) issues.
New to mastic? Which Mastic Gum Flavor to Start With will help you pick. Many customers also chew for face muscle work, covered in Gum for Face Muscles.
Want the full ranked list? See our best gum without a plastic gum base guide, which compares mastic and chicle brands side by side.
Does Gum of Gods have a plastic gum base?
No plastic gum base. Regular gum base contains plastics. Our mastic packs are tree resin. Each tin is raw Chios mastic, and the ingredient list is one line long.
A 2025 pilot study presented at the American Chemical Society found chewing gum can release microplastics. The study also found natural and synthetic gums released similar amounts. Gum of Gods was not part of this study. We share that result because the research on particles in saliva is new and we would rather you hear it from us.
Mastiha is produced only in southern Chios, and we buy our mastic from the Chios Mastic Growers Association. That narrow origin is one reason real mastic costs more than supermarket gum, and one reason fakes exist. Our buyer's guide shows how to spot the difference.
How to switch from regular gum without missing it
- Swap one daily gum session for one mastic session first.
- Warm one or two tears in your mouth for 20 to 30 seconds before chewing hard.
- Expect a firmer chew and a pine, slightly herbal taste. If you want sweeter, start with the Peppermint Pack.
- Keep a reusable gum tin in your bag so the habit travels.
The bottom line
Regular gum base contains plastics, and the FDA's list of allowed gum base ingredients includes synthetic polymers. Natural gums are not a magic fix: the 2025 ACS study found natural and synthetic gums released similar amounts, and nobody yet knows the full health picture. What you can control is the base.
Chios mastic is a single tree resin, from Chios, with no synthetic gum base added.
If you want to try it, start with The Classic Pack.
FAQ
What is in regular chewing gum base?
Regular gum base contains plastics. US rules (21 CFR 172.615) let chewing gum base include synthetic polymers such as polyvinyl acetate, polyethylene, polyisobutylene, butyl rubber and butadiene-styrene rubber. Labels usually just say gum base.
What did the 2025 ACS chewing gum study find?
A 2025 pilot study presented at the American Chemical Society found chewing gum can release microplastics. The study also found natural and synthetic gums released similar amounts. Gum of Gods was not part of this study.
What is Chios mastic gum made of?
Chios mastic is a single natural tree resin, the hardened sap of Pistacia lentiscus, hand harvested on the Greek island of Chios. No synthetic gum base is added. The resin itself is the chew.
How is mastic different from natural chicle gums?
Chicle gums use a Central American tree latex, often blended with other ingredients. Chios mastic is a resin from a different tree on one Greek island, chewed with no added base. It is firmer and has a piney taste.
How can you lower microplastic exposure from gum?
Chew one piece longer instead of swapping often. In the UCLA pilot, 94% of particles were released in the first 8 minutes.
Your next steps
- Swap your first pack of regular gum for The Classic Pack.
- Not sure about the taste? Start with the Sample Pack.
- Like it sweeter? Go with the Peppermint Pack.
- See everything in our mastic gum collection.
Keep reading
- Chios mastic gum benefits hub
- Best mastic gum: how to choose
- The sleep and breathing stack
- Gum for face muscles
References
- US Code of Federal Regulations, 21 CFR 172.615, "Chewing gum base." https://www.law.cornell.edu/cfr/text/21/172.615
- American Chemical Society. Chewing gum can shed microplastics into saliva, pilot study finds. March 25, 2025. https://www.acs.org/pressroom/presspacs/2025/march/chewing-gum-can-shed-microplastics-into-saliva-pilot-study-finds.html
- American Chemical Society. Microplastics found in chewing gum. Headline Science. June 24, 2025. https://www.acs.org/pressroom/headline-science/chewing-gum-microplastics.html
- Lowe L, Leonard J, Mohanty S. Ingestion of microplastics during chewing gum consumption. Journal of Hazardous Materials Letters, 2025. doi:10.1016/j.hazl.2025.100164 https://doi.org/10.1016/j.hazl.2025.100164
- European Medicines Agency, herbal monograph: Mastic (Pistacia lentiscus L., resin). https://www.ema.europa.eu/en/medicines/herbal/mastic