There are some positives to the gnawing habit of chewing gum. When sugarless gum was chewed for 20 minutes after meals, it decreased cavities. Another study found it increased saliva production and decreased the uncomfortable feeling of dry mouth.

Despite these benefits from chewing gum, there is a new risk to consider: A single stick of chewing gum potentially releases hundreds of thousands of pieces of microplastics into our saliva that we're likely to swallow, a study from the University of California, Los Angeles (UCLA) has found.

Most microplastics were released from chewing gum during the first two minutes it was put in the mouth.

Microplastics and nano-plastics are found practically everywhere in our environment, and they're particularly bountiful in the food we eat.

These tiny pieces of plastics end up in our body's organs, from our brains, kidneys and liver to testes, and even fetal placentas.

Some scientists have estimated the average person eats 5 grams of microplastics in a week — about the weight of a credit card. That's roughly 52,000 particles annually from various food sources.

UCLA researchers conducted a series of experiments involving 10 different commercially-available brands of gum. Five were naturally-based and five were synthetic. What's the difference? Natural gum products are made with a rubber base composed of plant-based polymers like chicle or other kinds of tree sap. Synthetically composed gum uses petroleum-based polymers.

“Our initial hypothesis was that the synthetic gums would have a lot more microplastics because the base is a type of plastic,” Lisa Lowe, a UCLA biological engineer and one of the study's co-authors, said in a press statement. “Surprisingly, both synthetic and natural gums had similar amounts of microplastics released when we chewed them.”

In one experiment each piece of gum was chewed by a single participant for four minutes, with saliva samples collected every 30 seconds until the end, when they were combined with a final mouth rinse of clean water. The experiment was repeated seven times for each brand of gum.

In a second experiment, repeated saliva samples were collected for individual analysis over the course of 20 minutes of chewing. The goal was to determine the rate at which microplastics were released from each piece of gum.

The number of microplastic particles in each sample was measured by staining the particles red and counting them under a microscope where their chemical composition was analyzed. The team found that one gram of gum released around 100 pieces of microplastic. It's worth noting that some pieces of gum released as many as 600 microplastics per gram.

The researchers also reported that the most microplastics were released from chewing gum during the first two minutes it was in the mouth — reaching 94 percent within the first 8 minutes. This was the result of the mechanical action, rather than the enzymatic properties of saliva.

Because of these findings, Lowe recommended that if you want to keep chewing gum, you can reduce your exposure to microplastics if you chew one piece for longer — rather than having multiple pieces of gum.

if you want to keep chewing gum, you can reduce your exposure to microplastics if you chew one piece for longer — rather than having multiple pieces of gum.

The researchers also highlighted how discarded chewing gum can present a plastic threat to our environment. That's because the plastic that's released into our saliva is only a small fraction of the plastic that's in gum. That's why we shouldn't just throw our gum on the ground or stick it to a wall or under the table.

While microplastics are something we should definitely be keeping an eye on, the researchers agree that you needn't stop chewing gum just yet. But you should certainly dispose of it appropriately in a bin when you're done with it.

The research was presented at the American Chemical Society meeting in San Diego. Its findings have been submitted to a peer-reviewed journal, but it has not yet been published.