Single piece of chewing gum ‘releases thousands of toxic microplastics’ into your mouth – linked to cancer and dementia

A SINGLE piece of chewing gum releases thousands of toxic microplastics into your mouth to be swallowed, scientists have warned.

Tiny plastic particles shed by everyday items like cutting boards, water bottles, tea bags and even clothes, have previously been linked to dementia, cancer and heart disease.

Research published this month found some human brains contain up to 7g of plastic, which could be linked to dementia.

New research adds chewing gum to the growing list of items that may be putting our health at risk.

Sanjay Mohanty, the study’s principal investigator and an engineering professor at the University of California, Los Angeles (UCLA), said: “Our goal is not to alarm anybody.

“Scientists don’t know if microplastics are unsafe to us or not. There are no human trials.

“But we know we are exposed to plastics in everyday life, and that’s what we wanted to examine here.”;

Scientists estimate that humans are exposed to tens of thousands of microplastics– plastic fragments measuring between 1 micrometer and 5 millimetres wide – every year through foods and drinks, plastic packaging, non-stick coating on cookware and production or manufacturing processes.

But chewing gum hasn't been widely studied as a potential source of microplastics, scientists said at the American Chemical Society conference in San Diego.

Prof Mohanty and a graduate student in his lab, Lisa Lowe, wanted to identify how many microplastics a person could potentially ingest from chewing natural and synthetic gums.

Synthetic chewing gum is made from a rubbery base using from petroleum-based polymers, laced with sweetener, flavourings and other ingredients.

Meanwhile, natural gums use a plant-based polymer, such as chicle or other tree sap, to achieve the right chewiness.

Polymer are large molecule made up of many smaller, repeating units called monomers, which are joined together like links in a chain.

They can be natural, like rubber or DNA, or man-made, like plastic and are used in everyday items such as clothes, packaging, and tyres because they can be strong, flexible, or lightweight.

Ms Lowe said: “Our initial hypothesis was that the synthetic gums would have a lot more microplastics because the base is a type of plastic.”

Researchers tested five brands of synthetic gum and five brands of natural gum, all of which are commercially available in the US.

They had the same person chew seven pieces of gum from each brand, so that different chewing patterns and saliva of other participants didn't skew the results.

The person chewed each piece of gum for four minutes, and spat out samples of saliva every 30 seconds, before rinsing their mouth out with water.

In another experiment, researchers collected saliva samples from gum chewers over 20 minutes to get an idea of how much plastic each piece of gum released over that time.

They then measured the number of microplastics present in each saliva sample.

Plastic particles were either stained red and counted under a microscope or analysed by Fourier-transform infrared spectroscopy – a scientific technique used to identify and analyse the chemical composition of substances – which also gave them information about polymer composition.

Most gums released an average of 100 microplastics per gram of gum, though some individual gum pieces released as many as 600 microplastics per gram.

A typical piece of gum weighs between 2 and 6 grams, meaning a large piece of gum could release up to 3,000 plastic particles.

If the average person chews 160 to 180 small sticks of gum per year, the researchers estimated that they could be swallowing around 30,000 microplastics.

If the average person consumes tens of thousands of microplastics per year, gum chewing could greatly increase the amount they ingest.

Ms Lowe said: “Surprisingly, both synthetic and natural gums had similar amounts of microplastics released when we chewed them.”

And they also contained the same polymers.

Both types of gum contained large amounts of polyolefins, a group of plastics that includes polyethylene and polypropylene.

Most of the microplastics detached from gum within the first 2 minutes of chewing, but Prof Mohanty said they weren’t released because of enzymes in saliva breaking them down.

Instead, the act of chewing is abrasive enough to make pieces flake off.

And after eight minutes of chewing, 94 per cent of the plastic particles collected during the tests had been released.

This suggests that if people want to reduce their exposure to microplastics from gum, they should chew on one piece longer instead of popping in a new one, Ms Lowe said.

Because of the instruments and techniques used, the study only identified microplastics that were 20-micrometers-wide or larger.

So it's likely that smaller plastic particles went undetected and that additional research is needed to assess whether chewing gum sheds nano-sized plastics – fragments 10,000 times thinner than human hair – Prof Mohanty said.

He concluded: “The plastic released into saliva is a small fraction of the plastic that’s in the gum.

“So, be mindful about the environment and don’t just throw it outside or stick it to a gum wall.”;

If used gum isn’t properly thrown away, it’s another source of plastic pollution to the environment, too.

Animal studies and studies with human cells show that microplastics could cause harm, so scientists suggested that people take steps to reduce their exposure to microplastics.

Dr Brandon Luu, an internal medicine resident at the University of Toronto who studied microplastic accumulation in brains, said: “Bottled water alone can expose people to nearly as many microplastic particles annually as all ingested and inhaled sources combined.

“Switching to tap water could reduce this exposure by almost 90 per cent, making it one of the simplest ways to cut down on microplastic intake.”