In the natural environment, it takes gum between 20 to 25 years to biodegrade. Surprised? So was I. (And for the same reason, don't swallow your gum.)

But whether people know how long it persists or not, a lot of it still ends up on city streets — not to mention the underside of subway seats. But the city of Amsterdam is turning the scourge of used gum to its advantage: They're collecting the stuff that sticks to your soles to create more soles for shoes, in a wonderful example of sustainable design thinking.

According to UpRoxx: "Amsterdam-based clothing brand Explicit Wear partnered with city marketing organization Iamsterdam — the tourism website for the Dutch city — and sustainability company Gumdrop to break down the synthetic rubber properties in chewing gum to create a new type of rubber called Gum-Tec, and with it, a sustainable option for your feet."

How the shoes are made

Special teams work throughout the city of Amsterdam to pick up gum from the streets. It turns out that gum is the second most common litter after cigarette butts in the capital city of The Netherlands. After being collected, the gum is processed into the soles of the new sneakers.

"We discovered that gum was made from synthetic rubber, and by breaking down these properties, we were able to create a new type of rubber," said Anna Bullus, the designer of the sneakers, in the video above.

About 2.2 pounds of gum are needed for every four pairs of sneakers. With 3.3 million pounds of gum deposited on city streets each year, there's plenty to work with.

The goal is part creative recycling project, and the tagline for the shoe ("for the sole purpose of clean streets") reveals the second aim: a public-awareness campaign about littering. It's a subtle, high-design way of getting people to pitch their used chew in the trash.

Available in bubblegum pink (naturally) as well as black, the sneakers pair leather uppers with the gummy soles. They'll be available in June for about $230, which is a small price to pay for shoes that you can step on gum with — and do your part to clean the streets.

Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.