You May Be Horrified When You Learn What Chewing Gum Is Actually Made From

A researcher has identified a surprising source of plastic pollution: chewing gum.

In an essay for The Conversation, microplastics expert David Jones of the UK's University of Portsmouth revealed that most modern chewing gum contains "a variety of oil-based synthetic rubbers," akin to the stuff that car tires are made of — which is not only going into our bodies, but also the environment upon being spat out.

Mysteriously, Wrigley, the maker of "Double Mint" gum and the world's largest manufacturer of the chewy stuff, refuses to name what exactly goes into its products. On the page for its oral health program, the company says only that its synthetic base binds "all the ingredients together for a smooth, soft texture."

As Jones explained, a 2014 chemical analysis by the University of Arkansas revealed what Wrigley and other gum-makers would not: that sticks of chewing gum can contain everything from styrene-butadiene, which is what tires are made of; polyethylene, the chemical used for plastic bags; and polyvinyl acetate, which is better known as wood glue.

"The people I talk to are always surprised, and disgusted, when they find out they’ve been chewing on a lump of malleable plastic," the researcher wrote. "Most manufacturers just don’t advertise what gum is actually made of — they dodge around the detail by listing 'gum base' in the ingredients."

While there are no hard and fast statistics about how much gum gets made per year, educated estimates suggest that up to 1.74 trillion pieces get made per year. In his own research, Jones found that most pieces of gum weigh around 1.4 grams — which would mean that nearly 2.4 million tons, or about 5.4 billion pounds, of gum are manufactured every single year. Roughly a third of that weight, Jones noted, is synthetic gum base, which is quite a lot of chemicals that are put into mouths and spat out accordingly each year.

Those numbers get all the scarier when considering how durable gum is when littered. Because it's difficult and labor-intensive to clean up, discarded gum often stays stuck on pavements and underneath chairs, tables, and benches. Eventually, it breaks down and becomes microplastics — but that process, the researcher notes, can take decades.

While there are industry-funded campaigns to help people dispose more properly of gum waste, those companies "making a financial contribution to clean-up efforts is like plastic manufacturers paying for litter pickers and bin bags at volunteer beach cleans," according to Jones.

"Neither addresses the root cause of the problem," the researcher added — which is that such inorganic and potentially toxic materials are allowed to be put into a nominal food product, to begin with.

While it's hard to tell how much chewing gum is contributing to the microplastic problem plaguing our planet, it's an important reminder of the many unusual sources of pollution we don't often consider.

"Chewing gum pollution is just another form of plastic pollution," Jones concluded.

More on plastic pollution: Scientists Just Discovered Something Absolutely Horrifying About Microplastics