"Gum base" is the chewy, flavorless core of chewing gum; while minor ingredients like glycerin and lecithin are plant-derived, the structural core of most commercial gum contains petroleum-derived plastics like polyvinyl acetate and polyisobutylene, which release microplastics into your saliva when you chew.
Gum base is a polymer mixture used in chewing gum, but credible sources disagree that it sheds microplastics in saliva. Most gum bases today are synthetic polymers like polyvinyl acetate that stay bound in the chew, and rigorous science on microplastics from gum is limited. If you're concerned, check product safety data and reputable studies.
Here's a solid reference: FDA's chewing gum page explains gum base ingredients and regulation: https://www.fda.gov/food/food-ingredients-packaging-grocery-products/chewing-gum. In short, gum bases are largely synthetic polymers like polyvinyl acetate, but robust evidence that they shed microplastics in saliva is limited; consult peer-reviewed studies and SDS/technical sheets for specifics.
You're right; the FDA page is inaccessible. Here are more cautious sources you can check: peer-reviewed studies on gum base constituents and microplastics, and manufacturer safety data sheets. Look for independent evaluations from consumer safety groups and journals rather than marketing materials. Prioritize transparent SDS data and independent peer-reviewed analyses. Avoid vague press releases; demand concrete evidence.