The Dutch government formally announced yesterday that it's banning the use of khat—an East African leaf that's chewed as a stimulant. “If taken in moderation there are no major problems, but an investigation showed it to be problematic among some 10% of khat users, leading to health and social issues,” says immigration department spokesman Frank Wassenaar. Khat has been chewed for centuries by people in Ethiopia, Kenya, Somalia and Yemen. But Wassenaar claims the drug is especially problematic within the Netherlands' Somali community. Around 843 tons of khat—valued at $18 million—passed through Amsterdam's Schiphol Airport in 2010, up from 714 tons in 2009. Fifteen of the European Union’s 27 states currently list khat as an illegal narcotic, while the US bans it as a Schedule I drug. The Netherlands has been trying to distance itself from its drug-loving reputation, with foreigners being phased out of Dutch "coffee" shops this year.