Globally, people chew roughly 100,000 tonnes of gum each year, but what happens once we’ve finished with it? Ancient civilisations chewed tree resins such as chicle, but by the 1950s this had been replaced by synthetic gums. Alongside this gum base, modern chewing gum contains softeners such as vegetable oil, emulsifiers that reduce stickiness, fillers like talc to add bulk, plus flavourings, sweeteners, preservatives and colourings. Synthetic gums are generally not biodegradable, but in some cases they can be recycled into new plastic products. New, more sustainable chewing gum alternatives use natural gums like tree sap or rubber.