If you live in a major metropolitan city, you've perhaps noticed that the sidewalks are covered with black dots the size of quarters. It takes some time to figure out that they are chewing gum waste. North American kids alone spend approximately half a billion dollars on bubble gum every year.

Chewing gum crisis has grown dramatically in recent years. It is now one of the world's most popular forms of confectionery and consumption has jumped in the past years. As a result, a rash of gum blobs has spread across cities and towns all over. At the same time, the cost of cleaning has become extremely expensive, about three times more than producing the stuff in the first place.

After it's spit out, it gets stepped on and flattened to the concrete. In no time at all it accumulates the ebony patina of city grime. Sprinkling the sidewalks is easy. Removing the tarred, synthetic rubber is the hard part. If you're talking about one chewed stick in a school hallway, it's a can of solvent and a putty knife away from coming off the floor. But when you've got miles of city walkways to clean, you need something better. Widely used solvents, such as acetone and ether, used commonly to clean this mess are either poisonous or inflammable and so could not be released in public places. But now researchers at Belfast and Manchester (UK) believe they have found a simple answer: enzymes.

Because gum is a kind of synthetic rubber, it repels water, so the removal agent needs to be suspended in some kind of solvent.
The mixture they're currently at work on uses a substance known as an ionic liquid, which is basically molten salt. The salts they've been testing have very low melting points and are biodegradable, unlike the more corrosive alternatives. They believe they're about a year off from getting it right and bringing the product to market.