People who eat chewing gum may be increasing their intake of microplastics, a US study suggests. Testing of saliva samples for 10 brands found a single piece could release up to 3,000 plastic particles.
The health effects of ingested microplastics are not yet fully understood but research has shown they can penetrate deep into human tissues including the brain — and they have been found all over the Earth, including in remote Antarctica. The study’s principal investigator Professor Sanjay Mohanty, an expert in engineering at the University of California in Los Angeles, 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.”
Chewing gums are made from a rubbery base, sweetener, flavourings and other ingredients. Natural gums use a plant-based polymer while other products use synthetic rubber bases from petroleum-based polymers.
The researchers theorised that synthetic chewing gums would contain more microplastics because the base is a type of plastic, so they tested five brands of each type.
In one experiment, a volunteer chewed each piece of gum for four minutes, producing saliva samples every 30 seconds, then a final mouth rinse with clean water, all of which were combined into a single sample.
In a second test, saliva samples were collected periodically over 20 minutes to look at the release rate of microplastics.
Analysis found there were an average of 100 microplastic particles per gram of gum, rising to 600 plastics for some gums.
The team calculated that a typical piece of gum weighs between two and six grams, meaning a large piece 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 could result in the ingestion of around 30,000 microplastics.
Project leader Lisa Lowe, who started the project as an undergraduate intern at UCLA, said: “Surprisingly, both synthetic and natural gums had similar amounts of microplastics released when we chewed them.”
Most of the microplastics released from the gum were detected within the first two minutes of chewing.
Therefore, Ms Lowe suggested people could release their exposure by chewing one piece of gum for longer rather than starting a new one.
Prof Mohanty added that used gum will still contain plastic particles. He said: “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.”
Professor Oliver Jones, an expert in chemistry at the Royal Melbourne Institute of Technology (RMIT), cautioned that the study had not yet been peer-reviewed.
He added: “The idea that chewing gum might be a source of microplastics is not that new in itself, but this is the first study to attempt to quantify the potential problem.
“An interesting finding from this study is that they found very similar microplastics of microplastics in both the synthetic and the natural gums, even though there weren’t supposed to be plastics in the natural gums at all.
“While microplastics are something we should definitely be keeping an eye on, I don’t think you have to stop chewing gum just yet – although you should certainly dispose of it appropriately in a bin when you are finished with it.”
