No gum allowed!

In 1992 chewing gum was banned from Singapore. Chewing gum was causing serious maintenance problems in all areas of the city-state. After the 1987 launch of the $5 billion mass transit train system, it was reported that vandals had begun sticking chewing gum on the door sensors of the trains, preventing the doors from functioning properly and causing disruption of train services. Surprisingly, after the ban no known black market for chewing gum ever emerged in Singapore, although some citizens did occasionally manage to smuggle some from Malaysia for their own consumption. In 2004 the ban was revised to recognize the proven health benefits of certain gums that contain calcium lactate to strengthen tooth enamel. The sale of this newly categorized medicinal gum was allowed, as long as it was sold by a dentist or pharmacist, who is required to record the name of the purchaser.