In today’s world avoiding interaction with plastics is well-nigh impossible; they are ubiquitous and present everywhere in our daily lives. Plastics are now even within our bodies in the form of micro- and nano-plastics that come from the clothing we wear, the food we eat, the water we drink, and even from the air we breathe.
Now a new study shows that chewing gum is yet another way that these micrometer sized plastic particles enter our body. Researchers at the University of California, Los Angeles (UCLA) in the United States found that chewing gum can release hundreds to thousands of microplastics per piece into our saliva and potentially into our body.
Although animal studies and studies with human cells show that microplastics could cause harm, scientists have yet to categorically identify the exact harm that microplastics cause to the human body. While we wait for more definitive answers from the scientific community, individuals can take several steps to reduce their exposure to microplastics.
Scientists estimate that humans consume tens of thousands of microplastics that range in size between 1 micrometer (1/1000 of a millimeter) and 5 mm-wide every year through foods, drinks, plastic packaging, coatings, and production or manufacturing processes. Yet, chewing gum as a potential source of microplastics has not been widely studied, despite the candy’s worldwide popularity. The research team at UCLA wanted to identify how many microplastics a person could potentially ingest from chewing natural and synthetic gums.
Chewing gums are made from a rubbery base, sweetener, flavorings and other ingredients. Natural gum products use a plant-based polymer, such as chicle or other tree sap, to achieve the right chewiness, while synthetic gum products use rubber bases from petroleum-based polymers.
The researchers tested five brands of synthetic gum and five brands of natural gum, all of which are commercially available. To reduce the human factor of varied chewing patterns and saliva, they had seven pieces from each brand all chewed by one person.
In the lab, the person chewed the piece of gum for four minutes, producing samples of saliva every 30 seconds, then a final mouth rinse with clean water, all of which got combined into a single sample. In another experiment, saliva samples were collected periodically over 20 minutes to look at the release rate of microplastics from each piece of gum. Then, the researchers measured the number of microplastics present in each saliva sample.
Plastic particles were either stained red and counted under a microscope or analyzed by Fourier-transform infrared spectroscopy, which also provided the polymer composition. The team found an average of 100 microplastics released 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 could result in the ingestion of around 30,000 microplastics.
The initial hypothesis of the researchers was that the synthetic gums would have a lot more microplastics because the base is a type of plastic. Surprisingly, both synthetic and natural gums were found to have similar amounts of microplastics released when chewed upon. And they also contained the same polymers: polyolefins, polyethylene terephthalates, polyacrylamides and polystyrenes. The most abundant polymers for both types of gum were polyolefins, a group of plastics that includes polyethylene and polypropylene.
Most of the microplastics detached from gum within two minutes of first chewing the gum. And they were not released because of enzymes in saliva breaking them down, rather by the very action of chewing on them. The study also found that after eight minutes of chewing, 94 percent of the plastic particles collected during the tests had been released.
To reduce the potential exposure to microplastics from chewing gum, people who are habituated to chewing this product would be better advised to chew one piece of gum for a longer period, rather than pop a new gum into their mouth more frequently.
The study was limited to identifying microplastics 20-micrometers-wide or larger because the instruments and techniques used were able to detect only up to those sizes. The researchers pointed out that it is very likely that smaller plastic particles were present in the saliva but were not detected, and that additional research would be needed to assess the potential release of nano-sized (one-billionth of a meter) plastics from chewing gum.
