Chemists at the University of Bristol have come up with a formulation for chewing gum that could make gum-marked pavements a thing of the past. Terry Cosgrove and his team have developed a new polymer additive that, when added to the gum recipe, renders it water soluble. "Chewing gum contains a lot of hydrophobic - water hating - polymers, which prevent the material from breaking down in water," explains Cosgrove. This makes it difficult to wash off because the water-repellent quality of the gum prevents water from penetrating and dissolving the material. "But our formulation contains hydrophilic - water loving - groups, which, when added to the mixture, allow water molecules to interact with the gum and break it down." The result is a material indistinguishable from traditional gum but which disintegrates into fine flakes after prolonged water exposure; but hardcore chewers need not worry, it shouldn't melt in your mouth! Another spin-off is that the new polymer formulation, which is currently undergoing safety tests and is already licensed for use in human foods, also intensifies the flavour of the gum by helping the flavourants to interact with water in the mouth, and the tastebuds. "We're hoping to have this on the market by 2008," says Cosgrove.