“Our initial hypothesis was that the synthetic gums would have a lot more microplastics because the base is a type of plastic,” Lisa Lowe, the study’s co-collaborator and a graduate student in Mohanty’s lab, explained in a statement. (Yes, certain types of synthetic gum contain petroleum-based polymers.)

Are you keeping a mental list of all the sources of microplastics finding their way into your daily life? You may have another culprit to consider: It’s gum, according to a new pilot study that found chewing just one piece can release hundreds to thousands of microplastics into saliva.

Chewing a single piece of gum can release hundreds to thousands of pieces of microplastic into the saliva in your mouth—likely to go on to be swallowed. This is the warning of researchers from the University of California,