I put that in my mouth?

Slate.com featured an article by Brian Palmer called "How Green Is My Wintergreen?"  As a constant gum-smacker, I was most disturbed to find out what was actually in gum.  Yes, it's a tacky habit, but I bet most people would drop it if you told them it was made of a synthetic polymer known as polyisobutene, and not biodegradable. Palmer also notes that it's a constant nuisance in urban environments, and points out that the city of London spent millions of dollars to remove it from the streets in preparation for the 2012 Olympics, money that could be spent on more pressing environmental issues. 

If you still don't want to quit, try www.Project7.com, which plants 1 fruit tree for every tube of gum you buy.  Oddly, the gum tastes like pine trees.