Is it safe to swallow chewing gum ?

Chewing gum used to be from a rubber plant, but is now artificial. It sticks to the road because it contains long oily polymer chains which are chemically similar to some of the constituents of the road surface. It's very hard wearing stuff and doesn't get digested when you swallow it. It can cling onto the sides of your intestines and distort the gut, are occasionally trigger a dangerous disorder called intussusception where the gut telescopes inside itself, although this is rare in adults. It would be better for the environment if people could swallow it. Until then, it would be good to develop a family of chewing gum-consuming bacteria that could eat it off the pavement !