It's a non-sticky gum. Helps to keep our cities' sidewalks from the black circles known as 'gum on the sidewalk'. Dissolves in a few months (rain water does it) after it ends up on the ground, apparently tastes pretty good, and won't kill you!
And for those of you playing at home, you won't be the least surprised that it's from a bunch of researchers in the UK. Another reason to be an anglophile. This time we're talking Wales!